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Building Code Update Committee Packet 2011 03-21-11 v1'*0 United City of Yorkville J 1 "" 800 Game Farm Road EST. -1 1836 Yorkville, Illinois 60560 -4 A- Telephone: 630-553-4350 Q Fax: 630-553-7575 ALE AGENDA BUILDING CODE UPDATE COMMITTEE MEETING Monday, March 21, 2011 6:30 PM City Hall Conference Room 1. Call Meeting to Order 2. Roll Call 3. Approval of Meeting Minutes from February 9, 2011 4. Citizen's Comments 5. Old Business 1. National Electrical Code (2008) 6. New Business 7. Comments/Discussion 8. Next Phase of the Building Code Update Adoption Process 9. Adjournment UNITED CITY OF YORKVILLE BUILDING CODE UPDATE COMMITTEE Wednesday, February 9, 2011 6:30 p.m. City Council Conference Room 800 Game Farm Rd. Yorkville,IL 60560 Committee Members in Attendance: Alderman Rose Spears Fire Marshal Jeremy Canavan, Chairman Alderman Joe Plocher Don Duffy Richard Scheffrahn Adam Dontz Lynn Dubajic City Officials in Attendance: Krysti Barksdale-Noble, Community Development Director Paul Zabel, Building Code Official Guests in Attendance Greg Marker Meeting Called to Order Meeting was called to order at 6:42 p.m. Roll Call Roll call was taken a quorum was established. 2009 International Residential Code Mr. Zabel read the proposed amendment Section R105.2 was read. All one story detached structures which exceeds 100 square feet require permit. Alderman Plocher moved to approve, seconded by Mr. Dontz. Roll call vote taken, motion carried unanimously. Mr. Zabel read the proposed definition of"fence."An enclosure or barrier erected for the purpose of providing a boundary, protection, privacy screening or a decorative or ornamental gate. Alderman Plocher moved to accept the definition for fence; Fire Marshal Canavan seconded the motion. Discussion Mr. Duffy stated his opposition to permitting a decorative or ornamental structure such as an arbor or trellis. The committee discussed permanency as a guideline to require permit. Alderman Plocher amended his motion to add the language "permanent"before the word enclosure. Fire Marshal Canavan seconded the motion. A Roll call vote taken, motion carried unanimously. 2009 International Building Code Section 101.1 Title Mr. Zabel proposed inserting the name of the jurisdiction, United City of Yorkville. Fire Marshal Canavan moved to approve inserting the name of the jurisdiction, Alderman Spears seconded the motion. Motion carried by unanimous voice vote. Section 105.2 Work Exempt from Permit Mr. Zabel explained that the proposed amendment reflects the same information as in the 2009 International Residential Code. Alderman Plocher made the motion to approve, seconded by Mr. Dontz. Discussion The section referred to the types of fences which require permit. Mr. Scheffrahn pointed out that the section refers to commercial fences and suggested compromising at a height of four feet. Roll call vote did not carry. Aye: Nay: Duffy, Scheffrahn, Dontz, Dubajic, Canavan, Plocher, Spears . Mr. Scheffrahn made the motion to approve Section 105.2 with the exception of 4 foot high fences instead of fences 6 feet in height or taller requiring permit. Mr. Dontz seconded the motion. Roll call vote taken, motion carried unanimously. Section 1612.3 Establishment of Flood Hazard Areas Mr. Zabel explained as the City of Yorkville does not have its own flood maps, the name of jurisdiction inserted in the section should be Kendall County, and the date of February 4, 2009 the most current FEMA provided map. Mr. Dontz made the motion to accept. Mr. Scheffrahn stated any new map would have to be voted to amend the section. Alderman Plocher moved to strike the date and insert the language "most current". Fire Marshal Canavan seconded. Ms. Dubajic suggested inserting "the most current FEMA flood insurance map". Alderman Plocher amends his motion to accept this language. Fire Marshal Canavan seconded the motion. Discussion Mr. Dontz queried if an accepted flood map could be replaced by a more current map in the middle of a project. Ms. Dubajic explained with this language the current map would be applicable. Mr. Zabel stated that FEMA might have the power to override the City's jurisdiction. Roll call vote was taken. Aye: Canavan Nay: Dontz, Scheffrahn, Dubajic, Plocher and Spears Abstain: Duffy Ms. Dubajic made the motion to accept Section 1612.3 inserting the name of the jurisdiction as "Kendall County" and the date of"February 4, 2009". Alderman Plocher seconded the motion. Ms.Noble explained that only a governmental entity can request a change to an existing flood map with a letter of map revision or LOMAR. If an individual made a request for a flood map change the governmental entity would then investigate and make a recommendation, FEMA would make a site analysis, then the decision is proposed as a Conditional Letter of Map Revision or CLOMAR Roll call vote was taken, motion carried. Aye: Dontz, Scheffrahn, Duffy, Dubajic, Plocher Nay: Canavan, Spears Section 2901.1 Mr. Zabel explained that he added Illinois State Plumbing Code in addition to the International Plumbing Code and removed private sewage disposal systems from the code. The City is not planning to adopt a private sewage disposal code; Kendall County regulates private sewage disposal systems. Mr. Dontz moved to accept, Mr. Scheffrahn seconded, motion carried by unanimous voice vote. Section 3002.4 Elevators Fire Marshal Canavan explained this section addresses the size of an elevator in order to accommodate ambulance stretchers in structures exceeding two stories and to also require the "Star of Life" sign to let the emergency crews know which elevator would accommodate a stretcher. Mr. Scheffrahn asked if this would apply to single family homes and was told that single family homes were exempted from this section. Fire Marshal Canavan moved to accept Section 3002.4, Mr. Scheffrahn seconded the motion. Roll call vote was taken. Aye: Scheffrahn, Canavan, Spears Nay: Dontz, Duffy, Dubajic, Plocher Discussion Ms.Noble commented that the point of view expressed by the committee is concerned with retrofitting existing buildings and bringing in new business to the City. She stated that the code adopted by the city has to be at best the most we can do for life safety. Historically developers and builders have come on line when the codes are changing. Mr. Scheffrahn asked if the Smith Engineering Building's elevators accommodate stretchers. Ms Dubajic answered in the affirmative. The committee discussed new commercial buildings already in compliance of the 2009 Code. Ms. Dubajic read the motion to approve Section 3002.4 to include language to exempt single family homes or existing buildings with elevators. Mr. Scheffrahn seconded the motion. Roll call vote was taken and the motion carried. Aye: Dontz, Scheffrahn, Dubajic, Canavan, Plocher, Spears Nay: Duffy 2009 Existing Building Code Fire Marshal Canavan moved to accept as written, Ms. Dubajic seconded. Discussion Mr. Zabel explained that this code expands on Chapter 11 of the 2009 International Building Code and clarifies and identifies specific situations, allowing the developer more flexibility in meeting codes and requirements. Mr. Zabel identified the three methods as prescriptive compliance, work area compliance and performance compliance. Fire Marshal Canavan asked if the Code Official can prescribe the method used. Mr. Zabel answered that the Code Official does have some leeway in approving which method is used. Roll call vote was taken and the motion carried. Aye: Scheffrahn, Duffy, Dubajic, Canavan, Plocher, Spears Nay: Abstain: Dontz 2008 National Electric Code Mr. Zabel explained the NEC is more detailed than the ICC Codes and is published by the NFPA, a family of codes. He hadn't offered any amendments because of the technical details of the code. Mr. Scheffrahn asked if there were amendments to the 2002 NEC. The amendments were read; electric board was deleted in its entirety,penalties were deleted, inspector qualifications were deleted, the jurisdiction was inserted, acceptance date was also deleted. Fire Marshal Canavan discussed the reference in the 2002 NEC to NFPA80 which releases the City of Yorkville from liability. Mr. Zabel told the committee that liability issues are referenced in the other codes and in his opinion the 2008 NEC should be adopted as written. Mr. Marker stated that his expert could not be present at the meeting but had wanted to speak about the GFI/arc faults and the expense that it would add to a project. Mr. Dontz voiced his concern about approving the 2008 NEC without additional expert analysis for the committee to study. Alderman Spears asked for documentation on the major changes. Alderman Plocher suggested that a union electrician speak to the committee. Mr. Dontz made the motion to table 2008 NEC until March 21, 2011, Mr. Scheffrahn seconded the motion. Discussion Ms.Noble explained the timing to adopt the new codes; staff compiles all the codes and presents a comprehensive memo to the City Attorney for review, then it goes to the EDC, then a public hearing followed by presentation to City Council. This process will take 6-10 weeks. Mr. Dontz asked if the committee can present everything but the electric code to council. He was told that the city administrator would make that decision. Unanimous voice vote to table discussion of the 2008 NEC carries. Mr. Dontz made the motion for staff to request the committee to see the code adoption process through to completion. Mr. Scheffrahn seconded the motion. Discussion The committee reviewed the procedure for submitting to city council. Motion carried by unanimous voice vote. Adiournment Meeting adjourned at 8:40 p.m. Next meeting March 21, 2011. Respectfully submitted by:D Weinert Q cl s- Reviewed By: 0+ Legal El Agenda Item Number Finance F-1 leas Engineer ❑ Tracking Number -4 y City Administrator ❑ g 0 2Q Consultant ❑ CLE titi ❑ Agenda Item Summary Memo Title: Building Code Update City Council/COW/Committee Agenda Date: BCUC—Monday, March 21St, 2011 Synopsis: Discuss the National Electrical Code (NEC 2008) Council Action Previously Taken: Date of Action: Action Taken: Item Number: Type of Vote Required: Council Action Requested: Submitted by: Paul Zabel Building and Zoning Name Department Agenda Item Notes: alp Memorandum J � EST. 1836 To: Building Code Update Committee From: Paul Zabel, Chief Building Code Official .4 n nns­ �p CC: Krysti J. Barksdale-Noble, Community Development Director ALE Date: February 10, 2011 Subject: Approved Amendments to 2009 IRC and 2009 IBC Below are the approved amendments to the 2009 versions of the International Residential Code (IRC) and the International Building Code (IBC). Staff is not recommending any changes to the National Electrical Code(NEC). The 2008 NEC handbook will be available for review on the day of the meeting. Electronic and paper copies will be provided at the meeting. The text in raid indicates revisions to staffs recommendations made by the committee. International Residential Code 1. Section R105.2 Work Exempt from permit.Shall be amended to read as follows: Building: 1. One-story detached accessory structures used as tool and storage sheds, playhouses and similar uses,provided the floor area does not exceed 100 square feet( 9.29 m2). 2. Decorative, temporary, or similar type fences not over 4 feet(1829 mm)high. 3. Retaining walls that are not over 4 feet (1219 mm) in height measured from the bottom of the footing to the top of the wall,unless supporting a surcharge. 4. Water tanks supported directly upon grade if the capacity does not exceed 5,000 gallons(18,927L)and the ratio of height to diameter or width does not exceed 2 to 1. 5. fainting,papering,tiling,carpeting, cabinets, counter tops, and similar finish work. 6. Prefabricated swimming pools that are less than 24 inches(610 mm) deep. 7. Swings and other playground equipment. 8. Window awnings supported by an exterior wall which do not project more than 54 inches(1372 mm) from the exterior wall and do not require additional support. 2. Section R202,Definitions. Shall be amended to include the following definition: Fence. An permanent enclosure or barrier, such as wooden posts, wire, iron, or any other allowable material erected for the purpose of providing a boundary or as a means of protection, or to prevent uncontrolled access, or for privacy screening or confinement, or for decorative purposes (such as an ornamental gate). Materials used to contain or separate a garden area, an earthen stockpile, a storm water basin, or any other similar temporary use shall not be classified as a fence. International Building Code 1. 101,1 Title. Shall be amended to insert the name of jurisdiction- United City of Yorkville 2. 105,2 Work Exempt from permit. Shall be amended to read, in part, as follows: Building: 1 1. One-story detached accessory structures used as tool and storage sheds, playhouses and similar uses,provided the floor area does not exceed 100 square feet(9.29 m2). 2. Decorative, temporary, or similar type fences not over _feet(1829 mm)high. 3. 1612.3 Establishment of flood hazard areas. Shall be amended to insert the name of jurisdiction -- Kendall County; and to insert the Flood Insurance Rate Map effective date — February 4,2009. 4. 2901.1 Scope. Shall be amended to read as follows: The provisions of this chapter, the Illinois State Plumbing Code and the International Plumbing Code shall govern the erection, installation, alteration, repairs, relocation, replacement, addition to, use or maintenance of plumbing equipment and systems. Plumbing systems and equipment shall be constructed, installed and maintained in accordance with the International Plumbing Code and the Illinois State Plumbing Code. 5. 3002.4 Elevator car to accommodate ambulance stretcher. Shall be amended to read as follows: Where elevators are provided in buildings two or more stories above, or two or more stories below, grade plane, at least one elevator shall be provided for fire department emergency access to all floors. The elevator car shall be of such a size and arrangement to accommodate an ambulance stretcher 24 inches by 84 inches(610 mm by 2134 mm)with not less than 5-inch (127 mm) radius corners, in the horizontal, open position and shall be identified by the international symbol for emergency medical services (star of life). The symbol shall not be less than 3 inches (76 mm) high and shall be placed inside on both sides of the hoistway door frame. The inside hand rail shall be set at the maximum thirty six (36") inch height allowed under ADA standards to better accommodate the ambulance stretcher. The cab size is to be a minimum five(5') foot by seven (T) foot platform and minimum 2500 lb capacity with a 42" side slide door. Exception: Single-family homes. 2 Copyright© 2007,National Fire Protection Association`.All Frights Reserved NFPA 70° National Electrical Code' 2008 Edition This edition of NFPA 70, National Electrical Code, was prepared by the National Electrical Cade Committee and acted on by NFPA at its June Association Technical Meeting held June 3-7, 2007, in Boston. MA. It was issued by the Standards Council on July 26, 2007, with an effective date of August 15, 2007, and supersedes all previous editions. This edition of NFPA 70 was approved as an American National Standard on August 15, 2007. History and Development of the National Electrical Code The National Fire Protection Association has acted as sponsor of the National Electrical Code since 1911. The original Code document was developed in 1897 as a result of the united efforts of various insurance, electrical, architectural, and allied interests. In accordance with the provisions of the NFPA Regulations Governing Committee Projects, a National Electrical Code Committee Report on Proposals containing proposed amendments to the 2005 National Electrical Code was published by NFPA in July 2006. This report recorded the actions of the various Code-Making Panels and the Correlating Committee of the National Electrical Code Committee on each proposal that had been made to revise the 2005 Code.The report was circulated to all members of the National Electrical Code Committee and was made available to other interested NFPA members and to the public for review and comment. Following the close of the public comment period, the Code-Making Panels met, acted on each comment, and reported their action to the Correlating Com- mittee. NFPA published the National Electrical Code Committee Report on Comments in March 2007, which recorded the actions of the Code-Making Panels and the Correlating Committee on each public comment to the National Electrical Code Committee Report on Proposals.The National Electrical Code Committee Report on Proposals and the National Electrical Code Committee Report on Comments were presented to the 2007 June Association Technical Meeting for adoption. NFPA has an Electrical Section that provides particular opportunity for NFPA members interested in electrical safety to become better informed and to contribute to the development of the National Electrical Code and other NFPA electrical standards. At the Electrical Section Codes and Standards Review Session held at the 2007 NFPA World Safety Conference and Exposition, Section members had opportunity to discuss and review the report of the National Electrical Code Committee prior to the adoption of this edition of the Code by the Association at its 2007 June Technical Session. This 51st edition supersedes all other previous editions, supplements, and printings dated 1897, 1899, 1901, 1903, 1904, 1905, 1907, 1909, 1911, 1913, 1915, 1918, 1920, 1923, 1925, 1926, 1928, 1930, 1931, 1933, 1935, 1937, 1940, 1942, 1943, 1947, 1949, 1951, 1953, 1954, 1955, 1956, 1957, 1958, 1959, 1962, 1965, 1968, 1971, 1975, 1978, 1981, 1984, 1987, I990, 1993, 1996, 1999, 2002, and 2005. This Code is purely advisory as far as NFPA is concerned. It is made available for a wide variety of both public and private uses in the interest of life and property protection.These include both use in law and for regulatory purposes, and use in private self-regulation and standardization activities such as insurance underwriting, building and facilities construction and management, and product testing and certification. This 2008 edition includes the following usability features as aids to the user. Changes other than editorial are highlighted with gray shading within sections and with vertical ruling for large blocks of changed or new text and for new tables and changed or new figures. Where one or more com- plete paragraphs have been deleted, the deletion is indicated by a bullet (-) between the paragraphs that remain. The index now has dictionary-style headers with helpful identifiers at the top of every index page. 2008 Editiun NATIONAL ELECTRICAL CODE 70-1 CONTENTS Contents ARTICLE ARTICLE 90 Introduction ........................................ 70-- 21 III, Enclosures ...................................... 70– 90 IV. Disconnecting and Guarding ................ 70– 90 Chapter 1 General V. Plug Fuses,Fuseholders, and Adapters ... 70– 90 p VI. Cartridge Fuses and Fuseholders ........... 70– 91 100 Definitions ......................................... 70– 24 VII. Circuit Breakers ............................... 70– 91 70– 24 VIII. Supervised Industrial Installations ......... 70– 92 i. General Overcu li. Over 600 Volts, Nominal .................... 70— 31 IX. lrent Protection over 600 Volts, Nominal ............ 70- 93 ............................. 110 Requirements for Electrical Installations ..... 70- 32 250 Grounding and Bonding ............. 70- 94 I. General ......................................... 70- 32 I. General .......... 70- 94 II. 600 Volts, Nominal, or Less 70- 36 roue "" ""'."". •••••••••"""' 1l. System Grounding .... 70- 47 III. Over 600 Volts, Nominal ..... 70- 38 •••••••••••"" III. Grounding Electrode System and IV. Tunnel Installations over 600 Volts, Grounding Electrode Conductor "" "" . 70-•104 Nominal . 70- 40 ••••••••••••••••••••••••••••••••••••••'• IV. Enclosure,Raceway, and Service V. Manholes and Other Electrical Cable Connections . 70-109 ............................ Enclosures Intended for Personnel V. Bonding .. 70-109 Entry,All Voltages ... 70- 41 ..Grou nding.............quip.......... •••••••••••••••• V 1, Equipment Grounding and Equipment Grounding Conductors ........................ 70-113 Chapter 2 Wiring and Protection VII. Methods of Equipment Grounding ......... 70-117 200 Use and Identification of Grounded VIII. Direct-Current Systems ...................... 70-120 70- 43 IX, Instruments, Meters, and Relays ........... 70-121 Conductors ......................................... X. Grounding of Systems and Circuits of 210 Branch Circuits ................................... 70- 45 1 kV and Over (High Voltage) .............. 70-121 1. General Provisions ............................ 70- 45 280 Surge Arresters, Over 1 kV ..................... 70-123 1I. Branch-Circuit Ratings ....................... 70- 49 I• Genera] . . '. ....... 70-123 III. Required Outlets ••••••••'•'•'•'•• '...... 70- 52 II. Installation ..................................... 70-124 215 Feeders ............................................. 70- 55 1II. Connecting Surge Arresters ......I.,........ 70-124 220 Branch-Circuit, Feeder, and Service 285 Surge-Protective Devices(SPDS), I kV or Calculations ........................................ 70- 57 Less .................................................. 70-124 I. General ......................................... 70- 57 I. General ......................................... 70-124 II. Branch-Circuit Load Calculations .......... 70- 58 11. Installation ..................................... 70-125 III. Feeder and Service Load Calculations .... 70- 60 11I. Connecting SPDs. ............................. 70-125 IV. Optional Feeder and Service Load Calculations ..................................... 70-' 62 Chapter 3 Wiring Methods and Materials V. Farm Load Calculations .................... 70— 66 300 Firing Methods ................................... 70-126 225 Outside Branch Circuits and Feeders ......... 70– 67 I. General • 70_-. 67 I. General Requirements ....................I... 70-126 "" """"ng or Ot"""""" II. Requirements for over 600 Volts, it. More Than One Building or Other Nominal .................... 70-136 Structure __ 70- 70 .................... 70- 72 310 Conductors for General Winn III. Over 600 Volts ................................ g ................ 70-138 230 Services ............................................ 70- 73 312 Cabinets, Cutout Boxes, and Meter Socket 1. General ......................................... 70– 73 Enclosures .......................................... 70-164 11. Overhead Service-Drop Conductors ....... 70– 74 I. Installation ..................................... 70-164 111, Underground Service-Lateral II. Construction Specifications ................. 70-165 Conductors ...................................... 70– 75 314 Outlet, Device, Pull, and Junction Boxes; IV, Service-Entrance Conductors ............... 70– 76 Conduit Bodies; Fittings; and Handhole V. Service Equipment---General ............. 70– 78 Enclosures ....... 70-167 VI. Service Equipment—Disconnecting " """"' ""'"" " ' Means ............................................ 70– 78 I. Scope and General ............................ 70-167 VII. Service Equipment—Overcurrent II. Installation ..................................... 70-168 Protection ....................................... 70– 80 III. Construction Specifications ................. 70-174 VIII. Services Exceeding 600 Volts, IV. Pull and Junction Boxes for Use on Nominal ......................................... 70-- 81 Systems over 600 Volts,Nominal .......... 70-175 240 Overcurrent Protection ........................... 70– 83 320 Armored Cable: Type AC ....................... 70-175 I. General ......................................... 70– 83 I. General ......................................... 70-175 II. Location ........................................ 70– 86 II. Installation ..................................... 70-175 70-2 NATIONAL ELECTRICAL CODE 2008 Edition CONTENTS ARTICLE ARTICLE III. Construction Specifications ................. 70-177 348 Flexible Metal Conduit: Type FMC ........... 70-194 322 Flat Cable Assemblies: Type FC ............... 70-177 I. General ........... 70-.194 .............................. 1. General ................................ 70-177 11. Installation ..................................... 70-195 II. Installation ..................................... 70-177 350 Liquidtight Flexible Metal Conduit: Type III. Construction ................................... 70-178 LFMC ............................................... 70-196 324 Flat Conductor Cable: Type FCC .............. 70-178 I. General ......................................... 70-196 I. General ......................................... 70-178 11. Installation ..................................... 70-196 11. Installation ..................................... 70-178 III. Construction Specifications ................. 70-197 III. Construction ................................... 70-180 352 Rigid Polyvinyl Chloride Conduit: Type 326 Integrated Gas Spacer Cable: Type IGS ...... 70-180 PVC ................................................. 70-197 1. General ......................................... 70-180 1. General ......................................... 70-197 IL Installation ................................... . 70-180 I1. Installation ..... 70-197 ................... Ill. Construction Specifications ............. ... 70-181 III. Construction Specifications ................. 70-200 328 Medium Voltage Cable: Type MV .......... .. 70-181 353 High Density Polyethylene Conduit: Type I. General ......................................... 70-181 HDPE Conduit ..................................... 70-200 II. Installation ..................................... 70-181 I. General ......................................... 70-200 Ill.III. Construction Specifications ................. 70-182 IL Installation ..................................... 70-200 I 330 Metal-Clad Cable: Type MC .................... 70-182 II. Construction Specifications ................. 70-201 354 Nonmetallic Underground Conduit with 1. General .................................... 70-182 Conductors: Type NUCC ....... 70-201 II. Installation ..................................... 70-182 ........... 111. Construction Specifications ................. 70-183 I. General ......................................... 70-201 332 Mineral-Insulated, Metal-Sheathed Cable: II. Installation ..................................... 70--201 Type MI ............................................. 70--184 111. Construction Specifications ................. 70-202 1. General ......................................... 70-1$4 355 Reinforced Thermosetting Resin Conduit:..................... 70-203 II. Installation ..................................... 70-184 Type RTRC .................... III. Construction Specifications ................. 70-185 1. General ......................................... 70-203 334 Nonmetallic-Sheathed Cable: Types NM, 11. Installation ..................................... 70-203 NMC, and NMS ................................... 70-.185 III. Construction Specifications ................. 70-204 ................ 70-185 356 Liquidtight Flexible Nonmetallic Conduit: 1. General ll. Installation ............................ Type LFNC......... 70-185 •............................ ............ 70-205 III. Construction Specifications ................. 70-187 I. General ......................................... 70-205 336 Power and Control Tray Cable: Type TC .... 70-1$8 1I. Installation ............................ ........ 70-206 111. Construction Specifications ................. 70-207 1. General ......................................... 70-188 358 Electrical Metallic Tubin • T 11. Installation ..................................... 70-188 g ype EMT ........ 70-207 Ill. Construction Specifications ................. 70-188 1. General ......................................... 70-207 338 Service-Entrance Cable: Types SE and 11. Installation ............................ ........ 70-207 USE ......................................... 70-189 III. Construction Specifications ................. 70-208 I. General ......................................... 70-189 360 Flexible Metallic Tubing: Type FMT ......... 70-208 II. Installation ..................................... 70-189 I. General ......................................... 70-208 III. Construction ................................... 70-•190 It. Installation ..................................... 70-209 340 Underground Feeder and Branch-Circuit 111. Construction Specifications ................. 70-209 Cable: Type UF .................................... 70-190 362 Electrical Nonmetallic Tubing: Type ENT ... 70-210 I. General ......................................... 70-190 1. General ......................................... 70-210 11. Installation ..................................... 70-190 II. Installation ..................................... 70-210 Ill. Construction Specifications ................. 70-191 III. Construction Specifications .................. 70-211 342 Intermediate Metal Conduit: Type IMC ...... 70-191 366 Auxiliary Gutters ................................. 70-212 I. General ......................................... 70-191 I. General ......................................... 70-212 II. Installation ..................................... 70-191 It. Installation ..................................... 70-212 III. Construction Specifications 70-192 III. Construction Specifications ................. 70-213 344 Rigid Metal Conduit: Type RMC .............. 70-192 368 Busways ............................................ 70-214 1. General ......................................... 70-192 I. General Requirements ........................ 70-2I4 II. Installation ..................................... 70-193 II. Installation ..................................... 70-214 III. Construction Specifications ................. 70-194 III. Construction ....... 70-215 2008 Edition NATIONAL ELECTRICAL CODE 70-3 CONTENTS ARTICLE ARTICLE IV. Requirements for Over 600 Volts, II, Construction Specifications ................. 70-249 Nominal ......................................... 70-216 Ill. Portable Cables Over 600 Volts, 370 Cablebus ........................................... 70-216 Nominal ......................................... 70-250 372 Cellular Concrete Floor Raceways ............ 70-217 402 Fixture Wires ...................................... 70-251 374 Cellular Metal Floor Raceways ................ 70-218 404 Switches ............................................ 70-255 I. Installation ................. 70-219 I, Installation ..................................... 70-255 11. Construction Specifications 70-258 II. Construction Specifications 70-219 """""""' ................. 376 Metal Wireways ................................... 70-219 406 Receptacles, Cord Connectors, and Attachment Plugs (Caps) ......................... 70-258 1. General ......................................... 70-219 408 Switchboards and Panelboards .. 70-262 11. Installation ......... 70-219 """""""' ................... III. Construction Specifications ................. 70-220 1. General ......................................... 70-262 378 Nonmetallic Wireways ""'........... 70-221 II. Switchboards .................................. 70-263 111, Panelboards ............. 70-263 ....................... I. General ......................................... 70-221 IV. Construction Specifications ................. 70-264 II. Installation ..................................... 70-221 409 Industrial Control Panels ..... ........................ 70-265 Ill. Construction Specifications ................. 70-222 380 Multioutlet Assembly ........."'"""""'......... 70222 I. Genera] ..................................... 70-265 II. Installation ..................................... 70-266 382 Nonmetallic Extensions .......................... 70-222 I11. Construction Specifications ................. 70-266 I. General ......................................... 70-222 410 Luminaires, Lampholders, and Lamps ........ 70-267 II. Installation ..................................... 70-223 III. Construction Specifications I. General ......................................... 70-267 (Concealable pecif i Nonmetallic Extensions II. Luminaire Locations ......................... 70-268 74-224 III. Provisions at Luminaire Outlet Boxes, only) .................................. Canopies, and Pans ...... 70-269 ...................... 384 Strut-Type Channel Raceway ................... 70-224 IV Luminaire Supports ........................... 70-269 1. Genera] ........... 70-224 V Grounding ...................................... 70-270 .............................. .... 70-271 11. Installation ...... 70-224 VI. Wiring of Luminaires .................... ..................... 11I. Construction Specifications ................. 70-225 VII. Construction of Luminaires ................. VIII. Installation of Lampholders ................. 70-273 386 Surface Metal Raceways ........................ 70-226 IX. Construction of Lampholders ............... 70-273 1. General .......... 70-226 X. Lamps and Auxiliary Equipment ........... 70-274 ....................... II. Installation 70-226 XI. Special Provisions for Flush and .................. .................. Ill. Construction Specifications ................. 70-226 Recessed Luminaires .......................... 7 XII. Construction of Flush and Recessed 388 Surface Nonmetallic Raceways ................ 70-227 Luminaires .................. 70-274 I. General ....................................... 70-227 XIII. Special Provisions for II. Installation ..................................... 70--227 Electric-Discharge Lighting Systems of III. Construction Specifications ................. 70-227 1000 Volts or Less ............................ 70-274 XIV. Special Provisions for 390 Underfloor Raceways ............................ 70-228 Electric-Discharge Lighting Systems of 392 Cable Trays ........................................ 70-229 More Than 1000 Volts ........................ 70-276 394 Concealed Knob-and-Tube Wiring """"". 70-235 XV. Lighting Track ................................. 70-277 XVI. Decorative Lighting and Similar I. General ......................................... 70-235 Accessories ..................................... 70-277 II. Installation ..................................... 70-236 411 Lighting Systems Operating at 30 Volts or III. Construction Specifications ................. 70-236 Less ................. 70-278 ................................. 396 Messenger-Supported Wiring ................... 70-237 422 Appliances ......................................... 70-278 .......................... I. General ......................................... 70-237 1. General ...... 70-276 11. Installation .......... 70-237 n ............................... •••••••••••••--'-' 11. Installation .............. 70-279 ....................... 398 Open Wiring on Insuiators ...................... 70-237 111. Disconnecting Means ........................ 70-281 I. General 70-237 1V. Construction ................................... 70-282 .................................... 70-238 V. Marking ..... 70-283 II. Installation ......... ................................... III. Construction Specifications ................. 70-239 424 Fixed Electric Space-Heating Equipment ..... 70-284 I. General ......................................... 70-284 Chapter 4 Equipment for General Use Ii. Installation ..................................... 70-284 400 Flexible Cords and Cables 70-240 ill. Control and Protection of Fixed Electric Space-Heating Equipment ......... 70-284 I. General ......................................... 70-240 IV. Marking of Heating Equipment ............ 70-286 70-4 NATIONAL ELECTRICAL CODE 2008 Edition CONTENTS ARTICLE AR'T'ICLE V. Electric Space-Heating Cables 70-286 III. Transformer Vaults .............. ............ 70-341 Vt. Duct Heaters ................................. 70-28$ VII. Resistance-Type Boilers .. 70-289 455 Phase Converters ................. 70.342 VIII. Electrode-Type Boilers ....................... 70-290 1. General .. 70-342 ...................... IX. Electric Radiant Heating Panels and It. Specific Provisions Applicable to Heating Panel Sets 70-290 Different Types of Phase Converters ....... 70-343 426 Fixed Outdoor Electric Deicing and 460 Capacitors ................. ., 70-344 . ............. ........ Snow-Melting Equipment .....................•.. 70-292 I. 600 Volts, Nominal, and Under ........... 70-344 1. General ........................................ 70-292 II, Over 600 Volts, Nominal .. 70-344 1I. Installation ..................................... 70-293 470 Resistors and Reactors III. Resistance Heating Elements 70-293 70-345 IV. Impedance Heating ........................... 70-294 L 600 Volts, Nominal, and Under ............ 70-345 V. Skin-Effect Heating 70-294 11. Over 600 Volts, Nominal .................... 70-346 VI. Control and Protection ....................... 70-295 480 Storage Batteries .................................. 70-346 427 Fixed Electric Heating Equipment for 490 Equipment, Over 600 Volts, Nominal ......... 70-347 Pipelines and Vessels ............................. 70--295 1. General "• ......... 70-295 I. General ......................................... 70-347 II. Equipment Specific Provisions ......... 70--347 [[. Installation 70-2q�6 Pe .......,•,...ts . "'••' III. Equipment—Metal-Enclosed Power Ill. Resistance Heating Elements .............. 70-296 Switchgear and Industrial Control IV. Impedance Heating 70-297 Assemblies ... Ind V. Induction Heating ... 70-297 ........................••.•. 70-350 "••'•"'••• IV, Mobile and Portable Equipment 70-352 VI. Skin-Effect Heating ........................ 70-298 V. Electrode-Type . ype Boilers ......... 70-352 VII. Control and Protection .. 70-29$ 430 Motors, Motor Circuits, and Controllers ...... 70-298 Chapter 5 Special pedal Occupancies . 1. General ......................................... 70-298 II. Motor Circuit Conductors ..... 70-,304 500 Hazardous {Classified} Locations, Classes I, 11, and I11, Divisions I and 2 .......... III. Motor and Branch-Circuit Overload ....... 70-354 Protection ....................................... 70-306 501 Class I Locations ....................I............ 70-362 IV. Motor Branch-Circuit Short-Circuit I. General and Ground-Fault Protection ...... 70-310 70-362 Il. Wiring ...................... 70-363 V Motor Feeder Short-Circuit and ••••••••••• Ground-Fault Protection ...................... 70-313 III• Equipment ...................................... 70--368 VI. Motor Control Circuits ....................... 70-313 502 Class 11 Locations ................................ 70-372 VII. Motor Controllers ............................. 70-315 I. General VIII. Motor Control Centers 70-316 70 372 IL Wiring ..................... 70-372 IX. Disconnecting Means ........................ 70-317 """"""' X. Adjustable-Speed Drive Systems ........... 70-320 111. Equipment ...................................... 70-374 XI, Over 600 Volts, Nominal .................... 70-321 503 Class III Locations ............................... 70-378 XII. Protection of Live Parts—All I. General ,•••• 70-378 Voltages ....... 70-322 .......................... .................................. II. Wiring 70-378 X111. Grounding---All Voltages ..... 70-323 "•""•."•"" "'""""'"' III, Equipment 70-379 XIV. Tables ...... 70-324 ............................... ..................................... 440 Air-Conditioning and Refrigerating 504 Intrinsically Safe Systems ....................... 70-380 Equipment .......................................... 70-327 505 Class 1, Zone 0, 1, and 2 Locations ........... 70-384 I. General ......................................... 70-327 506 Zone 20, 21, and 22 Locations for 11. Disconnecting Means ........................ 70-329 Combustible Dusts or Ignitible Ill. Branch-Circuit Shan-Circuit and FibetsJFlyingg ...................................... 70-398 Ground-Fault Protection ...................... 70-330 510 Hazardous (Classified) Locations— IV. Branch-Circuit Conductors .................. 70-331 Specific .......... 70404 V. Controllers for Motor-Compressors ........ 70-331 .................'•"•"""•••••' VI. Motor-Compressor and Branch-Circuit 511 Commercial Garages, Repair and Storage .... 70-404 VIL Overload Protection ........................... 70-332 513 Aircraft Hangars ...................... 70-407 Provisions for Room Air Conditioners .... 70-333 514 Motor Fuel Dispensing Facilities .............. 70-410 445 Generators ......................................... 70-334 515 Bulk Storage Plants ......., 70-414 450 Transformers and Transformer Vaults (Including Secondary Ties) ...................... 70-335 516 Spray Application, Dipping, and Coating Processes ............................................ 701119 I. General Provisions ............................ 70-335 IL Specific Provisions Applicable to 517 Health Care Facilities ............................ 701425 Different Types of Transformers ............ 70-339 1. General ......................................... 70425 2008 Edition NATIONAL ELECTRICAL CODE 70-5 CONTEN'T'S ARTICLE ARTICLE 1I. Wiring and Protection ........................ 70--427 551 Recreational Vehicles and Recreational III. Essential Electrical System .................. 70-430 Vehicle Parks ....................................... 70475 IV. Inhalation Anesthetizing Locations ........ 70-437 1. General ....•..•.•. 74--475 V. X-Ray Installations . 7040 """"""' lI. Combination Electrical Systems ............ 7077 V1. Communications, Signaling Systems, 111. Other Power Sources ......... -- 70 477 Data Systems, Fire Alarm Systems, and Systems Less Than 120 Volts, IV. Nominal 120-Volt or 120/240-Volt Nominal 70 41 Systems .......................................... 70-478 ..................................... V. Factory Tests .................... 70485 VII. Isolated Power Systems ......... . .... 70442 ' """' VI. Recreational Vehicle Parks .................. 70485 518 Assembly Occupancies .......................... 70443 552 Park Trailers ....................................... 70488 ................... 520 Theaters,Audience Areas of Motion I. General ......................................... 70-488 Picture and Television Studios. II. Low-Voltage Systems ........................ 70488 Performance Areas, and Similar Locations ... 70444 III. Combination Electrical Systems . 70-489 ........... I. General .................... 70-444..................... IV. Nominal 120-Volt or 1201240-Volt II. Fixed Stage Switchboards ................... 70446 Systems .......................................... III. Fixed Stage Equipment Other Than V. Factory Tests ................................... 70496 Switchboards ................................... 70-447 553 Floating Buildings ................................ 70497 IV. Portable Switchboards on Stage ............ 70448 V. Portable Stage Equipment Other Than 1. General ......................................... 70497 Switchboards ,,,,,..... 70-451 II. Services and Feeders ......................... 70497 ......................... VI. Dressing Rooms 70452 III. Grounding ...................................... VII. Grounding ...................................... 70453 555 Marinas and Boatyards .......................... 70498 522 Control Systems for Permanent 590 Temporary Installations .......................... 70-501 Amusement Attractions ........................... 70-453 L General ......................................... 70-453 Chapter 6 Special Equipment II. Control Circuits ...............I.,............. 70453 600 Electric Signs and Outline Lighting ........... 70-504 III. Control Circuit Wiring Methods ........... 70454 1. General ......................................... 70-504 525 Carnivals, Circuses, Fairs, and Similar 11. Field-Installed Skeleton Tubing and .............................................. 70455 .......... 70--508 Events Wiring ................................. 1. General Requirements ........................ 70455 604 Manufactured Wiring Systems ... 70-509 .............. 11. Power Sources ................................. 70455 605 Office Furnishings (Consisting of Lighting Ill, Wiring Methods ............................... 70456 Accessories and Wired Partitions) .............. 70--510 IV. Grounding and Bonding ..................... 70-457 610 Cranes and Hoists ................................ 70-51 530 Motion Picture and Television Studios and Similar Locations ............................ 70-457 I. General ......................................... 70-511 11. Wiring .......................................... 70-512 I. General ........................................1 70457 III. Contact Conductors ... 70-514 . 70458 ........................ I1. Stage or Set ................................... IV. Disconnecting Means ... 70-515 . 70460 ............. Ill. Dressing Rooms .......................... V. Overcurrent Protection 70-515 ....................... IV. Viewing, Cutting, and Patching Tables .... 70460 VI. Control ............. 70-516 ............................. V. Cellulose Nitrate Film Storage Vaults ..... 70460 VII. Grounding ................. 70-516 VI. Substations ..................................... 70460 g .................... 620 Elevators, Dumbwaiters, Escalators, 540 Motion Picture Projection Rooms ............. 70461 Moving Walks, Platform Lifts, and 1. General .... 70-461 Stairway Chairlifts ................................ 70-517 ............................ 11. Equipment and Projectors of the I. General ......................................... 70-517 Professional Type .............................. 70461 II. Conductors .................... 70-519 111. Nonprofessional Projectors .................. 70462 I1I. Wiring ........... 70--520 ....................... IV. Audio Signal Processing, IV. Installation of Conductors . 70-523 .................. Amplification, and Reproduction V. Traveling Cables .............................. 70-523 Equipment ...................................... 70-462 VI. Disconnecting Means and Control ......... 70-524 545 Manufactured Buildings ..... 70462 VII. Overcurrent Protection ....................... 70-526 .............. ViIl. Machine Rooms, Control Rooms, 547 Agricultural Buildings ........................... 70463 Machinery Spaces, and Control Spaces .... 70-526 550 Mobile Homes, Manufactured Homes, and IX. Grounding ...................................... 70-527 Mobile Home Parks .......... 70-466 X. Emergency and Standby Power Systems .......................................... 70-527 1. General ......................................... 70466 625 Electric Vehicle Charging System 70-527 11. Mobile and Manufactured Homes ......... 70467 III. Services and Feeders ......................... 70-474 I. General ......................................... 70-527 70-6 NATIONAL ELECTRICAL CODE 2008 Edition CONTENTS ARTICLE ARTICLE. II. Wiring Methods ............................... 70-528 II. Installation 70-573 ......................... III. Equipment Construction ..................... 70-528 III. Grounding and Bonding ............. 70-574 IV. Control and Protection ....................... 70-529 V. Electric Vehicle Supply Equipment 685 Integrated Electrical Systems ................... 70--575 Locations ........................................ 70-529 1. General ......... 70-575 ................... 626 Electrified Truck Parking Spaces 70-531 I1. Orderly Shutdown ............................ 70-575 1. General ................................... 70-531 690 Solar Photovoltaic Systems ..................... 70-575 11. Electrified Truck Parking Spaces I. General ........................ 70-575 Electrical Wiring Systems .................... 70-532 II. Circuit Requirements 70-578 II1. Electrified Truck Parking Space Supply III. Disconnecting Means ........................ 70-580 Equipment ...................................... 70-533 IV. Wiring Methods 70-581 ...................... Transport Refrigerated Units (TRUs) 70-535 V. Grounding .......... 70-583 630 Electric Welders ......................... 70-536 V1. Marking ........................................ 70-585 VII. Connection to Other Sources 70-585 1, General ........................................ 70-536 VIII. Storage Batteries ........... 70-587 11. Arc Welders .................................... 70-536 IX. Systems over 600 Volts .............. 70-588 Resistance Welders ........................... 70-537 IV. Welding Cable .................... 70-538 692 Fuel Cell Systems ................................ 70-588 640 Audio Signal Processing.Amplification, I. General ......................................... 70-588 and Reproduction Equipment .................... 70-538 11. Circuit Requirements ......................... 70-589 111, Disconnecting Means 70-589 1. General ...... 70-538 .............. ........................... IV, Wiring Methods . .............. 70-590 ............... . Permanent Audio System Installations .... 70-542 V. Grounding 70-590 . ........... Portable and Temporary Audio System Vl. Marking ............................................................................ Installations ..................................... 70-542 VII. Connection to Other Circuits . 70-590 .............. 645 Information Technology Equipment ........... 70-544 VIII. Outputs Over 600 Volts ...................... 70-591 647 Sensitive Electronic Equipment ................ 70-546 695 Fire Pumps ......................................... 70-591 650 Pipe Organs ........................................ 70-547 660 X-Ray Equipment . 70-548 Chapter 7 Special Conditions I. General ......................................... 70-548 700 Emergency Systems ......I....................... 70-596 It. Control .......................................... 70-549 I. General ............. 70-596 ............................ II1. Transformers and Capacitors ................ 70-549 I1. Circuit Wiring ........... 70-.597 IV. Guarding and Grounding .................... 70-549 III. Sources of Power .......... 70-598 665 Induction and Dielectric Heating IV. Emergency System Circuits for Equipment .......................................... 70-550 Lighting and Power ........................... 70-600 V. Control— Emergency Lighting 1. General ......................................... 70-550 Circuits .............................................................................. — II. Guarding, Grounding, and Labeling ....... 70-551 V1. Overcurrent Protection 70-600 ................... 668 Electrolytic Cells ................................. 70-551 701 Legally Required Standby Systems ............ 669 Electroplating ...................................... 70-554 I. General ............. 70-601 ............................ 670 Industrial Machinery ............................. 70-555 I1. Circuit Wiring ................................. 70-602 675 Electrically Driven or Controlled Ill. Sources of Power 70-602 Irrigation Machines ...... 70-556 IV. Overcurrent Protection ....................... 70-603 ............ . 1. General ......................................... 70-556 702 Optional Standby Systems ...................... 70-604 II. Center Pivot Irrigation Machines .......... 70-558 1. General ......................................... 70-604 680 Swimming Pools, Fountains, and Similar 11. Circuit Wiring ................................. 70-605 Installations ......................... 70-558 111. Grounding ...................................... 70-605 ������������� 1V. Sources of Power ............................ 70-605 I. General ....Inst Installed .00ls .................. 70-558 705 Interconnected Electric Power Production II. Permanently Installed Pools ............... . 70-561 III. Storable Pools ................................. 70--568 Sources .............................................. 70-605 IV. Spas and Hot Tubs 70-568 I. General ......................................... 7MO5 V. Fountains ....................................... 70-570 11. Utility-Interactive Inverters ................. 70-608 Vi. Pools and Tubs for Therapeutic Use ...... 70-572 Ill. Generators ....... 7109 VII. Hydromassage Bathtubs ..................... 70-572 7Q8 Critical Operations Power Systems 682 Natural and Artificially Made Bodies of (COPS) ...................................I.......... 70-609 Water ................................................ 70-573 I. General ..................................... 70-609 I. General ......................................... 70-573 II. Circuit Wiring and Equipment .... 70-610 2008 Edition NATIONAL ELECTRICAL CODE 70-7 CONTENTS ARTICLE ARTICLE III. Power Sources and Connection ............ 70-612 ITT. Protection ...................................... 70-655 IV. Overcurrent Protection ....................... 70-613 IV. Grounding Methods .......................... 70-656 V. System Performance and Analysis ......... 70-614 V. Installation Method$Within Buildings .... 70-657 720 Circuits and Equipment Operating at Less VI. Listing Requirements ......................... 70-659 Than 50 Volts ...................................... 70-614 830 Network-Powered Broadband 725 Class 1, Class 2, and Class 3 Communications Systems ........................ 70-660 Remote-Control, Signaling, and T. General ......................................... 70-660 Power-Limited Circuits ........................... 70-614 11. Cables Outside and Entering Buildings ... 70-662 1. General .......... 70-614 111. Protection ...................................... 70-664 """""""....""""' TV. Grounding Methods ..... 70-666 11. Class 1 Circuits 70�i15 '������������ 111. Class 2 and Class 3 Circuits ................ 70-617 V. lnstallatiort Methods Within Buildings .... 70-667 IV. Listing Requirements ......................... 70-622 TABLES VI. Listing Requirements ........................1 70-669 727 Instrumentation Tray Cable: Type ITC ........ 70-624 Chapter 9 Tables 760 Fire Alarm Systems .............................. 70-625 1 Percent of Cross Section of Conduit and T. General ......................................... 70-625 Tubing for Conductors ........................... 70-671 TL Non–Power-Limited Fire Alarm 2 Radius of Conduit and Tubing Bends ......... 70-671 (NPLFA) Circuits .............................. 70-626 4 Dimensions and Percent Area of Conduit 111. Power-Limited Fire Alarm (PLFA) Circuits .......................................... 70-628 and Tubing IV. Listing Requirements ......................... 70-631 (Areas of Conduit or Tubing for the Combinations of Wires Permitted in Table 770 Optical Fiber Cables and Raceways ........... 70-633 1,Chapter 9) ....................................... 70-672 T, General ......................................... 70-633 5 Dimensions of Insulated Conductors and II. Cables Outside and Entering Fixture Wires ....................................... 70-676 Buildings. ....................................... 70-634 5A Compact Copper and Aluminum Building III. Protection ...................................... 70-635 Wire Nominal Dimensions and Areas ......... 70-680 IV. Grounding Methods .......................... 70-635 V. Installation Methods Within Buildings .... 70-636 8 Conductor Properties ............................. 70-681 VT. Listing Requirements ......................... 70-638 9 Alternating-Current Resistance and Reactance for 600-Volt Cables, 3-Phase, Chapter 8 Communications Systems 60 Hz, 75°C (167°F)—Three Single Conductors in Conduit ............................ 70-682 800 Communications Circuits ........................ 70-640 11(A) Class 2 and Class 3 Alternating-Current I. General ......................................... 70-640 Power Source Limitations ........................ 70--684 TI. Wires and Cables Outside and l l(B) Class 2 and Class 3 Direct-Current Power Entering Buildings ............................. 70-641 Source Limitations ......... ......... 70-684 II1. Protection ... 7042 """"""" .......................... IV. Grounding Methods .......................... 70-644 12(A) PLFA Alternating-Current Power Source V. Installation Methods Within Buildings ... 70-645 Limitations .......................................... 70-685 VT. Listing Requirements ......................... 70-647 12(B) PLFA Direct-Current Power Source 810 Radio and Television Equipment ............... 70-649 Limitations .......................................... 70-685 I. General ......................................... 70-649 Annex A ............................................ 70-686 II. Receiving Equipment--Antenna Annex B ............................................ 70-689 Systems .......................................... 70-650 Annex C ............ 70-703 III. Amateur Transmitting and Receiving """""""" Stations—Antenna Systems ................ 70-652 Annex D ............................................ 70-763 IV. Interior Installation—Transmitting Annex E ... 70-773 ......................................... Stations .......................................... 70-653 Annex F ............................................ 70-774 820 Community Antenna Television and Radio Distribution Systems 70-653 Annex G ............................................ 70-776 ............................. I. General .... 70-653 Annex H ............................................ 7Q-778 ..................................... II. Coaxial Cables Outside and Entering Index ................................................ 70-785 Buildings ........................................ 70-654 70-8 NATIONAL ELECTRICAL CODE 2008 Edition NATIONAL ELECTRICAL CODE COMMITTEE NATIONAL ELECTRICAL CODE COMMITTEE These lists represent the membership at the time the Committee was balloted an the final text of this edition. Since that time, changes in the membership ma}• have occurred. A key to classifications is found at the back of this document. Technical Correlating Committee James W.Carpenter, Chair International Association of Electrical Inspectors,TX[E] Mark W.Earley, Sec'retan• National Fire Protection Association.MA (nonvoting) Jean A.O'Connor, Recording Secretary National Fire Protection Association. MA (nonvoting) James E. Brunssen, Telcordia Technologies, Inc.,NJ [UT] James M.Daly, General Cable, NJ [MI Rep.Alliance for Telecommunications Industry Solutions (Alt.to J.Pauley) Merton W.Bunker,Jr., U.S. Department of State,VA[U] Stanley J. Folz, Morse Electric Company,NV[IM] (VL to Document: I10. Document: 111,Document: 70, (Alt.to M. D.Toman) Document: 70B, Document: 70E,Document: 79) David L.Hittinger, IEC of Greater Cincinnati,OH [IM] William R.Drake, Marinco,CA fM] (Alt. to R.G.Wilkinson) Palmer L.Hickman, National Joint Apprentice&Training Neil F.LaBrake,Jr., National Grid,NY UT Committee,MD [L] [ 1 Rep. International Brotherhood of Electrical Workers (Alt. to J.W.Troglia) John R.Kovacik, Underwriters Laboratories Inc., [L[RTI Danny Liggett, Dupont Company,TX [U] William M.Lewis, Martinsville. IN [U] (Alt,to W.M. Lewis) Rep.American Chemistry Council Mark C.Ode, Underwriters Laboratories Inc.,NC [RTI Jim Paule_v, Square D Company/Schneider Electric, KY IMI (Alt.to J. R. Kovacik) Rep. National Electrical Manufacturers Association Richard P.Owen, City of St. Paul,MN [E] Michael D.Toman, MEGA Power Electrical Services,Inc., (Alt. to J.W.Carpenter) MD [IMI Rep.National Electrical Contractors Association Nonvoting John W.Troglia, Edison Electric Institute,WI [UT] David Mascarenhas, Canadian Standards Association, Rep. Electric Light& Power Gruup/EE1 Canada[RT] Robert G.Wilkinson, IEC Texas Gulf Coast,TX [IMI Richard G.Biermann, Biermann Electric Company,Inc., Rep. Independent Electrical Contractors,Inc. IA[IM] Alternates (Member Emeritus) Jeffrey Boksiner, Telcordia Technologies, Inc.,NJ [UT] D.Harold Ware, Libra Electric Company.OK [IM] (Alt,to J. E. Brunssen) (Member Emeritus) Committee Scope: This Committee shall have primary responsibility for documents on minimizing the risk of electricity as a source of electric shock and as a potential ignition source of fires and explosions. It shall also be responsible for text to minimize the propagation of fire and explosions due to electrical installations. CODE-MAKING PANEL NO. 1 Articles 90, 100, 110,Annex A, Annex G John D.Minick, Chair National Electrical Manufacturers Association,TX [M] Michael A.Anthony, University of Michigan,MI [Ul David L.Hittinger, [EC of Greater Cincinnati,OH [IM] Rep.Association of Higher Education Facilities Officers Rep.Independent Electrical Contractors,Inc. Louis A.Barrios, Shell Global Solutions,TX [U] Neil F.LaBrake,Jr,, National Grid,NY[UT] Rep.American Chemistry Council Rep.Electric Light& Power GroupiEEI Kenneth P.Boyce, Underwriters Laboratories Inc.. IL[RT] Randall R.McCarver, Telcordia Technologies,Inc.,NJ [U] William T.Fiske, Intertek Testing Services NA,Inc.,NY[RT] Rep.Alliance for Telecommunications Industry Solutions H.Landis Floyd, The DuPont Company, DE[Ul Lanny G.McMahill, City of Phoenix,AZ[E] Rep. Institute of Electrical& Electronics Engineers,Inc. Rep. International Association of Electrical Inspectors Palmer L.Hickman, National Joint Apprentice&Training Pe' Committee,MD[LI H.Brooke Stauffer, National Electrical Contractors Rep. International Brotherhood of Electrical Workers Association,MD[IM] 2008 Edition NATIONAL ELECTRICAL CODE 70-9 NATIONAL ELECTRICAL CODE COMMITTEE Alternates Gil Moniz, National Electrical Manufacturers Association, Mark Christian, IBEW Local Union 175,TN [L] MA[M] (Alt.to P. L.Hickman) (Alt.to 1.D.Minick) Benjamin R Dunrord, Ben Dunford Electric Company Inc., Alfredo M Ramirez, Underwriters Laboratories Inc.,IL[RT] TN [1M] (Alt.to K.P.Boyce) (Alt. to D.L. Hiltinger) John W.Mroglia, Edison Electric Institute,WI [UT] Ernest J.Gallo, Telcordia Technologies,Inc., NJ [U] (Alt.to N. F.LaBrake,Jr.) (Alt,to R. R.McCarver) Nonvoting Russell J.Helmick,Jr., Orange,CA[E] (Alt.to L. G. McMahill) Ark Tsissercv, City of Vancouver,Canada Donald H.McCullough,II, Washington Savannah River Rep.CSAICanadian Electrical Code Committee Company,SC[U] (Alt. to H.L.Floyd) CODE—MAKING PANEL NO. 2 Articles 210, 215, 220,Annex D, Chapter 9 Examples 1 through 6 Raymond W.Weber, Chair State of Wisconsin,WI [E] Rep.International Association of Electrical Inspectors Richard W.Becker, Engineered Electrical Systems, Inc., Alternates WA[U] James E.Degnan, Sparling,WA[U] Rep. Institute of Electrical &Electronics Engineers, Inc. (Alt.to R.W.Becker) Lawrence Brown, National Association of Home Builders, David A.Dini, Underwriters Laboratories Inc., IL[RT] DC[U] (Alt.to R.L. LaRocca) Frank Coluccio, New York City Department of Buildings, Daniel J. Kissane, Pass &Seymour/Legrand.NY[M] NY[E] (Alt. to J. Pauley) Thomas L.Harman, University of Houston-Clear Lake,TX William Ross McCorcle, American Electric Power,OK[UT] [SEl (Alt.to R.L.Purvis) Donald M.King, IBEW Local Union 313, DE[L] William J.McGovern, City of Plano,TX [El Rep. International Brotherhood of Electrical Workers (Alt.to R.W.Weber) Robert L.LaRocca, Underwriters Laboratories Inc.,NY[RT] Clifford L Rediger, Independent Electrical Contractors Brian J.Nenninger, The Dow Chemical Company,TX [U] Training Fund,CO [IM] Rep.American Chemistry Council (Alt.to R.G.Wilkinson) Jim Pauley, Square D Company/Schneider Electric,KY[M] Janet D.Skipper, IBEW Local Union 606, FL[L] Rep.National Electrical Manufacturers Association (Alt.to D.M. King) Ronald L.Purvis, Sharpsburg,GA[UT] Joseph E.Wiehagen, National Association of Home Rep. Electric Light &Power Group/EEI Builders, [ Michael D.Toman, MEGA Power Electrical Services, Inc.. (Alt.to o L L. Br[U] own) MD [IM] Nonvoting Rep.National Electrical Contractors Association William Burr, Canadian Standards Association,Canada tRT] Robert G.Wilkinson, IEC Texas Gulf Coast,TX [IM] Douglas A.Lee, U.S. Consumer Product Safety Rep.Independent Electrical Contractors, Inc. Commission,MD [Cl Andrew M.Trotta, U.S. Consumer Product Safety Commission,MD[C] CODE—MAKING PANEL NO. 3 Articles 300, 590, 720, 725, 727, 760, Chapter 9, Tables 11(A) and (B), and Tables 12(A) and (B) Richard P.Owen, Chair City of St. Paul,MN [E] Rep. International Association of Electrical Inspectors Lawrence S.Ayer, Biz Com Electric,Inc.,OH [IM] Ronald E.Moassen, Lemberg Electric Company, Inc., Rep,Independent Electrical Contractors,Inc. W1 [IM] Paul J. Casparro, Scranton Electricians JATC, PA[L] Rep.National Electrical Contractors Association Rep.International Brotherhood of Electrical Workers Juan C.Menendez, Southern California Edison Company. Les Easter, Allied Tube and Conduit,1L[M] CA[UT] Rep.National Electrical Manufacturers Association Rep. Electric Light&Power Group/EEI Sanford E.Egesdal, Egesdal Associates PLC,MN[M] Steven J.Owen, Steven J.Owen, Inc.,AL[IM] Rep.Automatic Fire Alarm Association, Inc. Rep.Associated Builders&Contractors,Inc. Thomas J.Guida, Underwriters Laboratories Inc.,NY[RT] David A.Pace, Olin Corporation,AL[U] Ray R.R.Keden, ERiCO,Inc.,CA[Ml Rep.American Chemistry Council Rep. Building Industry Consulting Services International 70-10 NATIONAL ELECTRICAL CODE 2008 Edition NATIONAL ELECTRICAL CODE COMMITTEE Melvin K.Sanders, Things Electrical Co.,Inc. Roger S.Passmore, Davis Electrical Constructors,Inc.,SC (TECo., Inc.), IA[U] [IM] Rep. Institute of Electrical&Electronics Engineers, Inc. (Alt,to S.J. Owen) John E.Sleights, St. Paul Travelers,CT[1] Marty L.Riesber.g, IBEW Local Union 22,MD [L) Alternates (Alt. to P.J.Casparro) Shane M. Clary, Bay Alarm Company,CA[M] George A.Straniero, Tyco/AFC Cable Systems, Inc.,NJ(Alt. to S. E. Egesdai) IM[(All. to L.Easter) Adam D.Corbin, Corbin Electrical Services, Inc..NJ [IM] (Alt. to L. S.Ayer) Robert J.Walsh, City of Hayward,CA[E]Danny Liggett, Dupont Company,TX [U] (Alt. to R.P. Owen) (Alt.to D.A. Pace) Nonvoting T.David Mills, Bechtel Savannah River, Inc.,SC [U] (Alt. to M. K. Sanders) Edward C.Lawry, Oregon,WI [E] Mark C.Ode, Underwriters Laboratories Inc.,NC [RT] (Member Emeritus) (All.to T.J.Guida) CODE—MAKING PANEL NO. 4 Articles 225, 230 James M.Naughton, Chair IBEW Local Union 103,MA[L] Rep. International Brotherhood of Electrical Workers Thomas L.Adams, Exclon Corporation, IL[UTJ Alternates Malcolm Allison, Ferraz Shawmut, Rep.Electric Light& Power EE[ Paul D.Barnhart Underwriters Laboratories Inc.,NC[RT] ut, M MA[M] + Robert J.Deaton, The Dow Chemical Company,TX [U] (Alt. to M.C.Ode) Rep. Institute of Electrical& Electronics Engineers, Inc. Mark D.Gibbs, BWXT Y-12, LLC,TN [U] Howard D.Hughes, Hughes Electric Company Inc.,AR JIM] (Alt.to R.J. Deaton) Rep. National Electrical Contractors Association Kenneth W.Hengst, EAS Contracting, LP,TX [IM] Mark C.Ode, Underwriters Laboratories Inc.,NC[RT] (Alt.to V.Zinnante) James J.Rogers, Towns of Oak Bluffs,Tisbury,West Mark R.Hilbert, Slate of New Hampshire,NH [E] Tisbury, MA[E] (Alt. to J.J. Rogers) Rep, International Association of Electrical Inspectors Philip M.Piqueira, General Electric Company,CT[M] John A.Sigmund, PPG Industries, Inc., LA[U] (Alt.to J.W.Young) Rep.American Chemistry Council Mark H.Sumrall, IBEW Local Union 527,TX [L] John W.Young, Siemens Energy&Automation,Inc.,GA[M] (Alt.to J.M. Naughton) Rep.National Electrical Manufacturers Association Peter R.Walsh, Ferraz Shawmut,MA[M] Vincent Zinnante, Advantage Electric,Inc.,TX [IM] (Alt. [o M.Allison) Rep. Independent Electrical Contractors, Inc. CODE-MAKING PANEL,NO. 5 Articles 200, 250, 280, 285 Ronald J•Toomer, Chair Toomer Electrical Company Inc.,LA[IM] Rep.National Electrical Contractors Association Jeffrey Boksiner, Telcordia Technologies, Inc., NJ [UT] Daleep C.Mohla, DCM Electrical Consulting Services,Inc., Rep.Alliance for Telecommunications Industry Solutions TX [U] David Brender, Copper Development Association, Inc.,NY Rep. Institute of Electrical&Electronics Engineers,Inc. IM] Gregory J.Steinmaa, Thomas &Belts Corporation,TN[M] Rep.Copper Development Association Inc. Rep.National Electrical Manufacturers Association Martin J. Breit,Jr., Wheatland Tube Company,NJ IM] Robert G.Stoll, Thomas Associates,Inc., OH [M) Rep,American Iron and Steel Institute Rep. Power Tool Institute,Inc Paul Dobrowsky, Innovative Technology Services,NY[U] Richard Temblador, Southwire Company,GA[M] Rep.American Chemistry Council Rep.The Aluminum Association Dan Hammel, IBEW Local Union 704, IA[L] C.Douglas White, CenterPoint Energy,Inc.,TX [UT) Rep. International Brotherhood of Electrical Workers Rep.Electric Light&Power Group/EEI G.Scott Harding, F. B. Harding, Inc.,MD [IM] Rep. Independent Electrical Contractors, Inc. Alternates William J.Helfrich, U.S. Department of Labor, PA[E] Harold G.Alexander, American Electric Power,OH [UT] Michael J.Johnston, International Association of Electrical (Alt. to C. D.White) Inspectors,TX [E] Ron D.Alley, Northern New Mexico IEC,NM [IM] Chuck Mello, Underwriters Laboratories Inc.,WA]RT] (Alt. to G.S. Harding) 2008 Edition NATIONAL ELECTRICAL CODE 74-11 NATIONAL ELECTRICAL CODE COMMITTEE Joseph P.DeGregoria, Underwriters Laboratories Inc.,NY Paul R.Picard, Tyco/AFC Cable Systems,Inc.,MA[M] [RT] (Alt.to R.Temblador) (Alt.to C. Mello) Elliot Rappaport, Electrio Technology Consultants, Inc.,FL Ronald Lai, FCI Electrical,NH [M] IUl (Alt.to G.J.Steinman) (Alt.to D.C.Mohla) Paul J.LeVasseur, Bay City JEATC,MI [L] Phil Simmons, Simmons Electrical Services,WA[M] (Alt.to D. Hammel) (Alt. to D.Brender) Richard E.Loyd, R&N Associates,AZ[M] David A.Williams, Delta Charter Township,MI [E] (Alt.to M.J. Brett,Jr.) (Alt.to M.J.Johnston) Michael E.McNeil, FMC CorporationlBio Polymer,ME[U] Nonvoting (Alt.to P. Dobrowsky) Nathan Philips, Integrated Electronic Systems,OR[IM] Robert A.Nelson, Canadian Standards Association,Canada (Alt.to R.J.Toomer) [RT] CODE-MAKING PANEL NO. 6 Articles 310, 400, 402, Chapter 9 Tables 5 through 9,Annex B Scott Cline, Chair McMurtrey Electric,Inc.,CA[IM] Rep.National Electrical Contractors Association Samuel B.Friedman, General Cable Corporation,RI[M] Alternates Rep.National Electrical Manufacturers Association Jacob Benninger, IBEW Local Union 241 JATC,NY[L] Robert L.Huddleston,Jr., Eastman Chemical Company, (Alt. to W.F. Laidler) TN [UI Peter E.Bowers, Satellite Electric Company, Inc., MD[IM] Rep.American Chemistry Council (Alt.to G.W. Kent) G.W."Jerry"Kent, Kent Electric&Plumbing Systems, James M.Daly, General Cable,NJ [M] TX [IM] (Alt.to J.S.Zimnoch) Rep. Independent Electrical Contractors,Inc. Timothy Edwards, Alcan Cable Company.GA[M] William F.Laidler, South Shore VoTech/IBEW 223,MA[L] (Alt.to P.R.Picard) Rep.International Brotherhood of Electrical Workers Richard A.Holub, E. 1. DuPont de Nemours&Company, L.Bruce McClung, Electrical Safety Consulting Services, Inc.,DE[U] Inc.,WV tU] (Alt.to R.L. Huddleston,Jr.) Rep.Institute of Electrical &Electronics Engineers,Inc. Lowell Lisker, American Insulated Wire Corporation,MA Paul R.Picard, Tyco/AFC Cable Systems,Inc.,MA[M] [M) Rep.The Aluminum Association (Alt.to S. B.Friedman) Oran P.Post, Akron,OH [E] Harry J.Sassaman, Forest Electric Corporation,NJ [IM] Rep.International Association of Electrical Inspectors (Alt. to S.Cline) Carl Timothy Wall, Alabama Power Company,AL[UT] Bradley J.Schmidt, Underwriters Laboratories Inc..IL[RT] Rep.Electric Light&Power Group/EEI (Alt.to A. D.Wetherell) Austin D.Wetherell, Underwriters Laboratories Inc.,NY John Stacey, City of St.Louis,MO [E] [RTI (Alt.to O. P.Post) Joseph S.Zimnoch, The Okonile Company,NJ [M] Donald A.Voltz, Mustang Engineering,Inc.,TX [U] Rep.Copper Development Association Inc. (Alt. to L. B.McClung) CODE-MAKING PANEL NO. 7 Articles 320, 322, 324, 326, 328, 330, 332, 334, 336, 338, 340, 382, 394, 396, 398 Gaylen D.Rogers, Chair Highland,UT[El Rep.International Association of Electrical Inspectors Martin D.Adams, Adams Electric, Inc.,CO[IM] Ronald G.Nickson, National Multi Housing Council,DC Rep.National Electrical Contractors Association Jul Harry C.Brown, IBEW Local Union 606.FL[L] John W."Wes"Ray, Duke Energy Corporation,NC[UT) Rep.International Brotherhood of Electrical Workers Rep.Electric Light&Power Group/EEI John J.Cangemi, Underwriters Laboratories Inc.,NY[RT] Gregory L.Runyon, Eli Lilly and Company, IN [U] James M.Daly, General Cable,NJ [M] Rep.American Chemistry Council Rep.National Electrical Manufacturers Association David E.Schumacher, Associated Builders&Contractors, Timothy Edwards, Alcan Cable Company,GA[M] Inc., IA[IM] Rep.The Aluminum Association H.R.Stewart, HRS Consulting,TX [U] Chris J.Fahrenthold, Design Electric,TX[IM] Rep.Institute of Electrical&Electronics Engineers,Inc. Rep. Independent Electrical Contractors,Inc. George A.Straniero, Tyco/AFC Cable Systems,Inc.,NJ Herman J.Hall, Austin,TX [M] [M] Rep.Society of the Plastics Industry,Inc. Rep.Copper Development Association Inc. 70-12 NATIONAL ELECTRICAL CODE 2008 Edition NATIONAL ELECTRICAL CODE COMMITTEE Alternates Samuel R.LaDart, City of Memphis,TN [L] William B. Cris(, Houston Stafford Electric Company,TX (Alt. to H.C.Brown) [IM] David Mercier, Southwire Company,GA [MI (Alt.to C.J. Fahrenthold) (Alt.to J. M. Daly) James D.Erwin, Celanew, Ltd.,TX [U] Dennis A.Nielsen, Lawrence Berkeley National Laboratory. (Ali, to G. L. Runyon) CA[U] Rogers Hester,Jr., Encore Wire Limited.TX [M] (Alt.to H. R.Stewart) (Alt.to G.A.Straniero) Peter Pollak, The Aluminum Association, Inc.,VA[M] James K.Hinrichs, State of Washington,WA[E] (Alt. to T. Edwards) (Alt. to G.D Rogers) Thomas H.Wood, Cecil B.Wood Inc., IL IIMI Jacob Killinger, Underwriters Laboratories Inc., IL IRTI (Alt.to M. D.Adams) (Alt. to J.J.Cangemi I CODE-MAKING PANEL NO. 8 Articles 342, 344, 348, 350, 352, 353, 354, 356, 358, 360, 362, 366, 368, 370, 372, 374, 376, 378, 380, 384, 386, 388, 390, 392, Chapter 9, Tables 1 through 4,Annex C Julian R.Burns, Chair Burns Electrical/Quality Power Solutions, Inc.,NC [IM] Rep. Independent Electrical Contractors,Inc. Joseph Dabe, City of St. Paul. MN [L] Alternates Rep. International ,Brotherhood 'Mo rao& of Electrical Workers Richard J.Berman, Underwriters Laboratories Inc., IL RT George R.I)auberger, Thomas&Betts Corporation,TN [M] [ ] Rep.National Electrical Manufacturers Association (Alt.to G. F.Walbrecht) James C. Dollins, Tyco1AFC Cable Systems, MA[M] Joyce Evans Blom, The Dow Chemical Company,CA[U] Rep.The Aluminum Association (Alt. to J.T.Dwight) Jaynes T.Dwight, Sasol North America, Inc.,LA IUl Duane A. Carlson, PRS Consulting Engineers,WA[U] Rep.American Chemistry Council (Alt.to M.S.Griffith) M.Shan Griffith, Kellogg, Brown& Root, Inc.,TX [U] Charles W.Forsberg, Shaker Heights, OH [M] Rep. Institute of Electrical & Electronics Engineers, Inc. (Alt.to D. H. Kendall) David G. Humphrey, County of Henrico,Virginia,VA[EI James M.Imlah, City of Hillsboro,OR IE] Rep. International Association of Electrical Inspectors (Alt.to D. G. Humphrey) David H.Kendall, Carlon, Lamson&Sessions,OH IMI Kevin J.Lippert, Eaton Corporation, PA[M] Rep,Society of the Plastics Industry, Inc. (Alt.to G. R.Dauberger) Richard E.Loyd, R& N Associates,AZ[M] Gregory L.Maurer, Wheatland Tube Company,AR[M] Rep,American Iron and Steel Institute (Alt. to R. E.Loyd) Stephen P.Poholski, Newkirk Electric Associates, Inc.,MI Gary W.Pemble, Montana Electrical JATC, MT ILI [IM] (Alt. to J.Dabe) Rep. National Electrical Contractors Association C.Ernest Reynolds, Hatfield-Reynolds Electric Company, George F.Walbrecht, Underwriters Laboratories Inc.,IL IRT] AZ[IMI Leslie R.Lielke, South Carolina Electric &Gas Company, (Alt.to J. R.Burns) SC IUT] Richard Temblador, Southwire Company, GA[M] Rep. Electric Light& Power Group/EEI (Alt.to 1.C. Dollins) CODE-MAKING PANEL NO. 9 Articles 312, 314, 404, 408, 450, 490 Robert A.McCullough, Chair Ocean County Construction Inspection Department,NJ [EI Rep, International Association of Electrical Inspectors Rodney I).Belisle, NECA-IBEW Electrical Training Trust, Bradford D.Rupp, Allied Moulded Products, Inc.,OH[M] OR [L] Rep.National Electrical Manufacturers Association Rcp. International Brotherhood of Electrical Workers Sukanla Sengupta, FMC Corporation,NJ [Ul Billy Breithreutz, Fluor Corporation,TX [U] Rep.Institute of Electrical &Electronics Engineers, Inc. Rep.Associated Builders&Contractors, Inc. Monte Szendre, Wilson Construction Company,OR [IM] Richard P.Fogarty, Consolidated Edison Company of New Rep. National Electrical Contractors Association York,Inc.,NY[UT] Ralph H.Young, Eastman Chemical Company,TN[U] Rep.Electric Light&Power Group/EEI Rep.American Chemistry Council Frederic P.Hartwell, Hartwell Electrical Services,Inc.,MA [SE] Alternates Thomas J.I.eMay, LeMay Electric, Inc.,GA[IM[ Rep. Independent Electrical Contractors, Inc. Charles L.Boynton, The DuPont Company,TX [U[ Robert D.Osborne, Underwriters Laboratories Inc.,NC[RT] (Alt.to R. H.Young) 2008 Edition NATIONAL ELECTRICAL CODE 70-13 NATIONAL ELECTRICAL CODE COMMITTEE Kevin J.Breen, Breen Electrical Contractors Inc.,NY[IM] Paul W.Myers, Innovene LLC,OH[U] (Alt. to T.J. LeMay) (Alt.to S. Sengupta) James C.Carroll, Square D Company/Schneider Electric, Donald R.OfferdahI, North Dakota State Electrical Board, TN [M] ND [E] (Alt.to B.D.Rupp) (Alt.to R.A.McCullough) Kenneth L.McKinney,Jr., Underwriters Laboratories Inc., Rhett A.Roe, IBEW Local Union 26 JATC,MD [L] NC [RT] (Alt.to R.D.Belisle) (Alt. to R. D.Osborne) James C.Missildine,Jr., Southern Company Services,Inc., AL[UTI (Alt. to R. P.Fogarty) CODE-MAKING PANEL NO. 10 Article 240 James T.Dollard,Jr., Chair IBEW Local Union 98, PA[L] Rep. International Brotherhood of Electrical Workers Charles K.Blizard, American Electrical Testing Company, Alternates Inc.,MA[IMI Robert R.Gage, National Grid,NY[UTI Rep. InterNational Electrical Testing Association (Alt.to C.Eldridge) Madeline Borthick, IEC of Houston,Inc.,TX [IM] Roderic Hageman, PRIT Service,Inc.,IL[IM] Rep. Independent Electrical Contractors,Inc. (Alt. to C.K Blizard) Dennis M.Darling, Ayres,Lewis,Norris&May,Inc.,MI[U] Robert J.Kauer, Middle Department Inspection Agency, Rep. Institute of Electrical&Electronics Engineers, Inc. Inc.,PA[E] Charles Eldridge, Indianapolis Power&Light Company. IN (Alt,to G.W.Williams) ]UT] Frank G.Ladonne, Underwriters laboratories Inc.,IL[RT] Rep.Electric Light&Power Group/EEI (Alt. to J.R. Kovacik) Carl Fredericks, The Dow Chemical Company,TX [U] Richard E.Lofton,II, IBEW Local Union 280,OR [L] Rep.American Chemistry Council C.W. Kimblin, Eaton E)ectrical Corporation,PA[M] (Alt.to J.T. Dollard,Jr.} Alan Manche, Square D Company/Schneider Electric, KY Rep. National Electrical Manufacturers Association John R. Kovacik, Underwriters Laboratories Inc.,IL[RT] IMl Robert W.Mount,Jr., Hussmann Corporation,MO[M] (Alt.to C.W. Kimblin) Rep.Air-Conditioning and Refrigeration Institute Vincent J.Saporito, Cooper Bussmann, MO [M] George J.Ockuly, O'Fallon,MO[M] (Alt.to G.J.Ockuly) Richard Sobel, Quantum Electric Corporation,NY[IM] Steve A.Struble, Freeman's Electric Service,Inc.,SD [IM] Rep.National Electrical Contractors Association (Alt.to M. Borthick) Gerald W.Williams, County of Ventura,California,CA[E] Steven E.Townsend, General Motors Corporation,MI [U] Rep. international Association of Electrical Inspectors (Alt.to D.M.Darling) CODE-MAKING PANEL NO. 11 Articles 409, 430, 440, 460, 470,Annex D, Example D8 Wayne Brinkmever, Chair Britain Electric Company,TX [IM] Rep.National Electrical Contractors Association Rick L.Bunch, Tecumseh Products Company,MI [M] Paul S.Hamer, Chevron Energy Technology Company.CA Rep.Air-Conditioning and Refrigeration Institute Jul J.Ron Caccamese, Alterman Electric Co., Ltd.,TX[L] Rep.American Petroleum Institute Rep. International Brotherhood of Electrical Workers Vincent J.Saporito, Cooper Bussmann,MO [M] Terry D.Cale, Hamer Electric,Inc.,WA[IM] Lynn F.Saunders, Brighton,MI [U] Rep.independent Electrical Contractors,Inc. Rep.Institute of Electrical&Electronics Engineers,Inc. Robert G.Fahey, City of Janesville,WI [E] Lawrence E.Todd, Intertek Testing Services NA,Inc.,OR Rep. International Association of Electrical Inspectors ]RT] William D.Glover, PPG Industries,Inc.,WV [Ul Ron Widup, Shermca Industries,Inc.,TX[IM] Rep.American Chemistry Council Rep.InterNational Electrical Testing Association Charles A.Goetz, Underwriters Laboratories Inc.,IL[RT] James R.Wright, Siemens Energy&Automation,Inc.,IL Paul E.Guidry, Fluor Enterprises, Inc.,TX [U] [Ml Rep.Associated Builders&Contractors,Inc. Rep.National Electrical Manufacturers Association Leo H.Haas,Jr., CenterPoint Energy, Inc.,TX [UT] Rep.Electric Light&Power Group/EEI 70-14 NATIONAL ELECTRICAL CODE 2008 Edition NATIONAL ELECTRICAL CODE COMMITTEE Alternates Thomas E.Moore, City of North Royalton, OH [EJ Larry W.Burns, Burns Electric, Inc.,TX [IM] iAlt. to R.G.Fahey) (All, to T. D.Cole) Arthur S.Neubauer, Colonial Pipeline Company, GA JU] Ralph M.Esemplare, Consolidated Edison Company of (Alt,to P.S. Hamer) New York,NY[UT[ George J.Ockuly, O'Fallon,MO [M[ (All. to L. H. Haas,Jr.) (Alt. to V.J. Saporita) James M. Fahey, IBEW Local Union 103. MA[L] Charles L.Powell, Eastman Chemical Company,TN [U] (Alt.to J. R. Caccamese) (Alt. to W. D. Gloved Stanley J.Folz, Morse Electric Company, NV JIM) Arthur J.Smith,HI, Waldemar S. Nelson &Company, (All. to W. Brinkmeyer) Inc.,LA JU] Barry G. Karnes, Underwriters Laboratories Inc.,CA[RT] (All. to L. F.Saunders) (Alt. to C.A. Goetz) Russell A.Tilif"any, Johnson Controls, Inc., PA IM] Robert J. Keough, Emerson Motor Company,MO [M] (Alt.to R. L. Bunch) (Alt. to J. R. Wright) CODE-MAKING PANEL NO. 12 Articles 610, 620, 625, 626, 630, 640, 645, 647, 650, 660, 665, 668, 669, 670, 685, Annex D, Examples D9 and D10 Timothy M.Croushore, Chair Allegheny Power, PA[UT] Rep. Electric Light& Power Group/EEI Kent B.Givens, Alcoa. Inc.,TX [MJ Alternates Rep,The Aluminum Association (VL to 610,625,630. 645,660,665,668, 669, 685) William E.Anderson, The Procter&Gamble Company,OH Thomas L.Hedges, Hedges Electric& Construction Inc., Jul CA[IM] (Alt. to R.C. Prichard) Rep.National Electncal Contractors Association Jeffrey W.Blain, Schindler Elevator Corporation,NY[MI Ron L.Janikowski, City of Wausau,Wisconsin.WI [EJ (VL to 610, 620,630) Rep. International Association of Electrical Inspectors (Alt. to A.Juhasz) Robert E.Johnson, ITE Safety, MA[U] Thomas M.Burke, Underwriters Laboratories Inc.,CA[RT] Rep. Information Technology Industry Council (Alt.to C.Sato) (VL to 640,645, 647,685) Jeffrey L.Holmes, IBEW Local Union I JATC.MO[L] Robert A.Jones, Independent Electrical Contractors, Inc., (All. to D.R.Quave) TX [IMI Tim McClintock, Wayne County,Ohio,OH [E] Andy Juhasz, Kone, Inc., IL[Ml (Alt.to R. L.Janikowski) Rep. National Elevator Industry Inc. Roger D.McDaniel, Georgia Power Company,GA[UTJ (VL to 610,620,630) (Alt. to T.M. Croushore) Todd Lottmann, Cooper Bussmann, MO [MI Peter Pollak, The Aluminum Association, Inc.,VA]M] Rep. National Electrical Manufacturers Association (VL to 610,625,630,645,660,665,668,669,685) Sam Marcovici, New York City Department of Buildings. (Alt.to K. B. Givens) NY[E] Lori L.Tennant, Square D Company/Schneider Electric,NC John H.Mortimer, lnductotherm Corporation,NJ [M] IM] (VL to 610,630.665,668,669) (Alt. to T. Lottmann) Ralph C. Prichard, Hercules Incorporated, DE[U] George S.Tidden, George's Electrical Service Inc.,TX JIMI Rep. institute of Electrical & Electronics Engineers, Inc. (All.to R.A.Jones) David R. Quave, IBEW Local Union 903,MS [LJ Charles M.Trout, Maron Electric Company, FL JIM] Rep. Intemational Brotherhood of Electrical Workers (Alt. to T.L. Hedges) Craig Sato, Underwriters Laboratories Inc.,CA[RI] Robert C.Turner, Oxford,MD[M] Arthur E.Schlueter,Jr., A. E.Schlueter Pipe Organ (VL to 610,630.665, 668,669) Company,GA IM] (Alt.to J. H.Mortimer) Rep.American Institute of Organ Builders (VL to 640,650) Nonvoting Kenneth White, Olin Corporation, NY[Ul Andre R.Cartal, Yardley, PA[EJ Rep.American Chemistry Council (Member Emeritus) 2009 Edition NATIONAL ELECTRICAL CODE 70-15 NATIONAL ELECTRICAL CODE COMMITTEE CODE-MAKING PANEL NO. 13 Articles 445, 455, 480, 690, 692, 695, 700, 701, 702, 705 Thomas H.Wood, Chair Cecil B.Wood Inc.,IL JIM] Rep. National Electrical Contractors Association Tarry L.Baker, Broward County Board of Rules& Herbert V.Whittall, Electrical Generating Systems Appeals,FL[E] Association,FL[M] Rep. International Association of Electrical Inspectors Timothy P.Zgonena, Underwriters Laboratories Inc.,IL Ward I.Bower, Sandia National Laboratories,NM [U] [RT] Rep.Solar Energy Industries Association (VL to 690,692,705) Alternates Douglas L.L.Elkins, ExxonMobil Chemical Company,TX Paul D.Barnhart, Underwriters Laboratories Inc.,NC [RT] [U] (Alt. to T.P.Zgonena) Rep.American Chemistry Council Daniel Balta,Jr., Constellation Power Source Generation, George W.Flach, George W.Ruch Consultant, Inc.,LA Inc.,MD[UT] [SE] (Alt. to B.N. Hornberger) Ernest J.Gallo, Telcordia Technologies,Inc.,NJ [U] Ron B. Chilton, North Carolina Department of Insurance, Rep.Alliance for Telecommunications industry Solutions NC [E] (VL to 445,480,690,692) (Alt.to T.L. Baker) Robert J.Gustafson, Ohio State University,OH [U] Larry D.Cogburn, Cogbum Bros,Inc., FL[IM] Rep.American Society of Agricultural&Biological (Alt.to T.H.Wood) Engineers Brian L.Crise, NIETC,OR[L1 Banks Hattaway, Hattaway Brothers, Inc.,AL[IM1 (Alt.to T.W.Stafford) Rep.Associated Builders&Contractors,Inc. Steven J.Fredette, UTC Fuel Cells,LLC,CT[M] Barry N.Hornberger, PECO Energy Company,PA[UT1 (VL to 690,692,705) Rep.Electric Light&Power GrouplEEI (Alt.to K.Krastins) Kenneth Krastins, Plug Power, Inc.,NY[M] John P.Goodsell, Hubbell Incorporated,CT[M] Rep.U.S.Fuel Cell Council (Alt,to J.S.Nasby) (VL to 690,692,705) Timothy D.Holleman, AC Corporation,NC [IM] James S.Nasby, Master Control Systems, Inc.,IL[M] (Alt,to D.W.Schamel) Rep.National Electrical Manufacturers Association Robert Swayne, P2S Engineering,Inc.,CA[U] Steven H.Pasternack, Intertek Testing Services NA,Inc., (Alt.to E.Rappaport) NY[RT] Elliot Rappaport, Electro Technology Consultants,Inc.,FL Dale A.Triffo, Shell Oil Products U.S.,TX [U] [Ul (Alt.to D.L.L.Elkins) Rep-Institute of Electrical &Electronics Engineers,Inc. Robert H.Wills, Intergrid,LLC,NH [U] Duke W.Schamel, Electrical Service Solutions, Inc.,CO (VL to 690,692,705) JIM] (Alt.to W.1. Bower) Rep. Independent Electrical Contractors,Inc. Nonvoting Todd W.Stafford, National Joint Apprentice&Training Committee,TN [L] David Mascarenhas, Canadian Standards Association, Rep. International Brotherhood of Electrical Workers Canada[RTj CODE-MAKING PANEL NO. 14 Articles 500, 501, 502, 503, 504, 505, 506, 510, 511, 513, 514, 515, 516 Donald Cook, Chair Shelby County Development Services,AL[E] Rep. International Association of Electrical Inspectors Troy Beall, B &D Industries,Inc.,NM [IM] William G.Lawrence,Jr., FM Global,MA[11 Rep. National Electrical Contractors Association L.Evans Massey, Rockwell Automation,SC [M] Marc J.Bernsen, IBEW Local Union 291,ID[L] Rep.Instrumentation,Systems,&Automation Society Rep.International Brotherhood of Electrical Workers Jeremy Neagle, Intertek ETL SEMKO,NY[RTj Edward M.Briesch, Underwriters Laboratories Inc.,IL JRT] Mike O'Meara, Arizona Public Service Company,AZ JUT] James D. Cospolich, Waldemar S.Nelson&Company Inc., Rep.Electric Light&Power Group/EEI LA[U] David B.Wechsler, The Dow Chemical Company,TX [U] Rep. Institute of Electrical & Electronics Engineers, Inc. Rep.American Chemistry Council Mark Goodman, Jacobs Engineering Group.CA[UI Mark C.Wirfs, R&W Engineering, Inc.,OR [U] Rep.American Petroleum Institute Rep.Grain Elevator and Processing Society Gregory D.Hall, Better-Way Electric, Inc.,CO[IM] Rep. Independent Electrical Contractors,Inc. Alternates Joseph H.Kuczko, Killark Electric Manufacturing Donald W.Ankele, Underwriters Laboratories Inc., IL[RT] Company,MO IM] Rep.National Electrical Manufacturers Association (Alt.to E. M. Briesch) 70-16 NATIONAL ELECTRICAL CODE 2008 Edition NATIONAL ELECTRICAL CODE COMMITTEE A. W. Ballard, Crouse-Hinds,NY[M] Ted H.Schnaare, Rosemount Incorporated, MN[M] (Alt.to J. H. Kuczka) (Alt. to L. E.Massey) Mark W. Bonk, Cargill Incorporated,MN JUl John L.Simmons, Florida East Coast JATC, FL[L[ (All. to M.C Wirfs) (Alt,to M.J. Bernsen) Dave Burns, Shell Exploration& Production Company, LA Donald W.Zipse, Zipse Electrical Engineering Inc.,PA IU] [UJ (Alt. to J. D.Cos Mich) (All. to M.Goodman) � Larry E. Fuhrman, City or Titusville, FL[E] Nonvoting (Alt.to D. Cook) Richard A.Holub, E. I, DuPont de Nemours&Company. Timothy J.Pope, Canadian Standards Association,Canada Inc., DE[U] IRT] (Alt. to D. B.Wechsler) Eduardo N.Solano, E.studio Ingeniero Solano S,A., Nicholas P. Ludlam, FM Global, United Kingdom [[J Argentina[SE] (Alt. to W. G. Lawrence,Jr.) Fred K.Walker, U.S. Department of the Air Force,FL[U[ Christopher P.O'Neil, NSTAR Electric&Gas Corporation, Rep.TC on Airport Facilities MA[UT] (All, to M.O'Meara) CODE-MAKING PANEL NO. 15 Articles 517, 518, 520, 522, 525, 530, 540 Donald J.Talka, Chair Underwriters Laboratories Inc.,NY[RT] James R.Duncan, Sparling Electrical Engineering& Kenneth E.Vannice, Leviton Manufacturing Company Inc., Technology Consulting,WA JU] OR [M] Rep. ]nstitule of Electrical &Electronics Engineers, Inc. Rep. U.S.Institute for Theatre Technology Ronald E.Duren, PacifiCorp,WA[UT] (VL to 518,520,525,530,540) Rep. Electric Light& Power GrouplEEI Michael Velvikis, High Voltage Maintenance Corporation, Douglas S. Erickson, American Society for Healthcare WI [IM] Engineering,VI [Ul Rep. InterNational Electrical Testing Association Mitchell K.Herter, Entertainment Technology/Genlyte,TX Andrew White, IBEW Local Union 3,NY[L] ]IMJ Rep. International Brotherhood of Electrical Workers Rep. Illuminating Engineering Society of North America James L.Wiseman, Square D Company/Schneider Electric,TN(VL to 518,520,525.530,540) Rep, National Electrical Manufacturers Association Kim Jones, Funtastic Shows,OR [U] Rep. Outdoor Amusement Business Association, Inc. Alternates (VL to 525) James L.Brown, Detroit Edison, DTE Energy, MI JUT] Edwin S. Kramer, Radio City Music Hall,NY ILJ (All. to R.E, Duren) Rep. International Alliance of Theatrical Stage Employees Matthew B.Dozier, IDesign Services,TN [Ul (VL to 518,520,525,530,540) (Alt.to J. R. Duncan) Larry Lau, U.S. Department of Veterans Affairs, DC[Ul Samuel B.Friedman, General Cable Corporation,RI [M] (VL to 517,518) (All. to J.L.Wiseman) Dennis W.Marshall, TAG Electric Companies,TX [IM] Stephen M. Lipster, The Electrical Trades Center,OH [L] Rep. Independent Electrical Contractors,Inc. (Alt. to A. White) Eugene E.Morgan, County of Clackamas,Oregon, OR [El Joseph R Murnane,Jr., Underwriters Laboratories Inc.,NY Rep. International Association of Electrical Inspectors IRTJ Hugh O.Nash,Jr., Nash Lipsey Burch,LLC,TN[SE[ (Alt. to D.J.Talka) Marcus R.Sampson, Minnesota Department of Labor& Rep.TC on Electrical Systems Industry,MN [EJ Bruce D.Shelly, Shelly Electric Company, Inc., PA[IM] (Alt.to E. E. Morgan) Rep.National Electrical Contractors Association James C.Seabury,III, Enterprise Electric, LLC,TN[IMJ Michael D.Skinner, CBS Studio Center,CA[U] (All. to D.W. Marshall) Rep.Alliance of Motion Picture and Television Producers Steven R.Terry, Electronic Theatre Controls Inc.,NY[M] (VL to 518.520,525,530, 540) (VL to 518,520,525,530,540) (Alt.to K. E.Vannice) 2008 Edition NATIONAL ELECTRICAL CODE 70-17 NATIONAL ELECTRICAL CODE COMMITTEE CODE-MAKING PANEL NO. 16 Articles 770, 800, 810, 820, 830 S.D. Kahn, Chair Tri-City Electric Company,Inc.,CA[IM] Rep.National Electrical Contractors Association J. Robert Boyer, GE Infrastructure,Security,NJ [M] Kyle E.Todd, Entergy Corporation,TX [UT] Rep. National Electrical Manufacturers Association Rep.Electric Light& Power GrouplEEi James E.Brunssen, Telcordia,NJ [U] Rep.Alliance for Telecommunications Industry Solutions Alternates Larry Chan, City of New Orleans,LA[E] Terry C.Coleman, National Joint Apprentice&Training Rep.International Association of Electrical Inspectors Committee,TN IL] Gerald Lee Dorna, Belden Wire&Cable,IN [M] (Alt,to H.C. Ohde) Rep. Insulated Cable Engineers Association Inc. Timothy D.Cooke, Times Fiber Communications,Inc.,VA Roland W.Gubisch, Intertek Testing Services NA,inc., MA [UTI 1RT1 (Alt.to S.C.Johnson) Robert L.Hughes, The DuPont Company,GA[U] Bill Hopple, Tyco/SimplexGrionell,CA[M] Rep.American Chemistry Council (Alt. to J. R.Boyer) Robert W.Jensen, dbi-Telecommunication Infrastructure Randolph J.Ivans, Underwriters Laboratories Inc.,NY[RT] Design,TX [MI (Alt.to S. L.Stene) Rep.Building Industry Consulting Services International Stanley Kaurman, CableSafe, Inc,/OFS,GA[M] Steven C.Johnson, Time Warner Cable,NC [UT] (Alt.to G.L.Dorna) Rep,National Cable&Telecommunications Association William,J.McCoy, Vernon Wireless,TX [U] Ronald G.Jones, Ronald G.Jones,P.E.,TX [U] Rep,Institute of Electrical &Electronics Engineers,Inc. (Alt. . R.G.Jones} Harold C.Obde, IBEW-NECA Technical Institute, IL IL] Robert P.McGann, City of Cambridge,MA[E] Rep. International Brotherhood of Electrical Workers (Alt.to L.Chan) Luigi G.Prezioso, M.C. Dean,Inc.,VA[IM] W.Douglas Pirkle, Pirkle Electric Company,Inc.,GA[IM] Rep.Independent Electrical Contractors, Inc. (Alt.to S.D. Kahn) James W.Romlein, MV Labs LLC,WI [MI David B.Schrembeck, DBS Communications,Inc.,OH Rep.Telecommunications Industry Association [IM] Susan L.Stene, Underwriters Laboratories Inc.,CA IRTI (Alt.to L.G. Prezioso) CODE-MAKING PANEL NO. 17 Articles 422, 424, 426, 427, 680, 682 Don W.Jhonson, Chair Interior Electric,Inc.,FL[IM] Rep.National Electrical Contractors Association Thomas V.Blewitt, Underwriters Laboratories Inc.,NY[RT] Kenneth M.Shell, Tyco Tbermal Controls,CA IM] Richard J.Cripps, Association of Home Appliance Rep.Copper Development Association Inc. Manufacturers,VA[M] (VL to 426,427) (VL to 422,424) Ronald Sweigart, E.I. duPont de Nemours&Company,Inc., Paul Crivell, Camp,Dresser&McKee Inc.,WA[U] DE[U] Rep.Institute of Electrical&Electronics Engineers, Inc. Rep.American Chemistry Council Larry M.Eils, National Automatic Merchandising (VL to 422,424,426,427,682) Lee L.West, Balboa Instruments, Inc.,CA[M] Association,IL[M] Rep.National Spa and Pool Institute (VL to 422) (VL to 680) Christopher S.Gill, New York Board of Fire Underwriters. Randy J.Yasenchak, IBEW Local Union 607,PA[LI NY[E] Rep. International Brotherhood of Electrical Workers Bruce R.Hirsch, Baltimore Gas&Electric Company,MD Alternates [UT1 Rep.Electric Light&Power GrouplEEI Dennis L.Baker, Springs&Sons Electrical Contractors Robert M.Milatovich, Clark County Building Department, Inc.,AZ[IM] NV[E] (Alt.to M.Ramirez) Rep.International Association of Electrical Inspectors Aaron B.Chase, Leviton Manufacturing Company, Inc.,NY Jurgen Pannock, Whirlpool Corporation,TN [M] IMI Rep.Air-Conditioning and Refrigeration Institute (Alt.to B.E.Rock) James E.Maldonado, City of Tempe,AZ[E] (VL to 422,424) Marcos Ramirez, Hatfield-Reynolds Electric company,AZ (Alt.to R.M., Associati) Wayne E.Morris, Association of Home Appliance [IM] Manufacturers.DC [M] Rep. Independent Electrical Contractors,Inc. (VL to 422,424) Brian E.Rock, Hubbell Incorporated,CT[M] (Alt. to R.J.Cripps) Rep.National Electrical Manufacturers Association Brian Myers, IBEW Local Union 98, PA[L] (Alt. to R.J.Yasenchak) 70--18 NATIONAL ELECTRICAL CODE 2009 Edition NATIONAL ELECTRICAL CODE COMMITTEE Ronald F.Schapp, Intertek Testing Services NA, Inc.,OH Robert E,Wisenburg, Coates Healer Company,Inc.,WA [RTJ [M] (Voting Alt.to Intertek Rep_) (VL to 680) Gary L.Siggins, Underwriters Laboratories Inc.,CA[RT] (Alt. to Lee L.West) (Alt.to T. V Blewitt) Nonvoting Joel G.Solis, Air-Conditioning& Refrigeration Institute,VA [M] Andrew M.Trotta, U.S. Consumer Product Safety (VL to 422,424) Commission,MD [C] (AIL to J. Pannock) Douglas A. Lee, U.S. Consumer Product Safety Commission,MD IC[ CODE-MAKING PANEL NO. 18 Articles 406, 410, 411, 600, 605 Michael N.Ber, Chair IEC.Houston.TX [IM] Rep. Independent]Electrical Contractors, Inc. Charles L.Bovnton, The DuPont Company,TX [U] Randall K.Wright, RKW Consulting, PA[SEJ Rep.American Chemistry Council Frederick L.Carpenter, Lithonia Lighting, GA[M] Alternates Rep. National Electrical Manufacturers Association Steve Campolo, Leviton Manufacturing Company, Inc..NY Paul Costello, NECA and IBEW Local 90 JATC,CT[L] [M] Rep. International Brotherhood of Electrical Workers (Alt.to F. L.Carpenter) Kenneth F. Kempel, Underwriters Laboratories Inc.,NC Robert T.Carlock, R.T. Carlock Company,TN JIM] [RT] (All. to M.N. Ber) Stephen G.Kiefer, Kieffer&Company, Inc.,WI [M] Melvyn J.Kochan, Young Electric Sign Company,NV[M] Rep. International Sign Association WL to 600) (VL to 600) (Alt.to S. G. Kieffer) Steven A. Larson, BWXT Y-I2,LLC.TN [U] Charles S.Kurten, Underwriters Laboratories Inc.,NY[RT] Rep. Institute of Electrical & Electronics Engineers, Inc. (Alt. to K. F. Kempel) Michael S.O'Boyle, Lightoiier Division of Genlyte Group, Amos D.Lowrance,Jr., City of Chattanooga,Tennessee, MA IM] TN[E] Rep.American Lighting Association (All. to T.S.Owens) (VL to 410,411) Terry K.McGowan, Lighting Ideas, Inc.,OH [M] Timothy S.Owens, City of Santa Clara,CA[EI (VL to 410,411) Rep.International Association of Electrical Inspectors (Alt.to M. S. O'Boyle) Jim F.Pierce, Intertek Testing Services NA, Inc.,OR[RT] Ronald Michaelis, South Bend Vicinity Electrical JATC, IN Michael W.Smith, Schaeffer Electric Company,MO [IM] [L] Rep.National Electrical Contractors Association (Alt.to P.Costello) Sondra K.Todd, Westar Energy, Inc., KS [UT[ Ronald Sweigart, E.I.duPont de Nemours&Company. Inc., Rep, Electric Light& Power Group/EEI DE[UI Jack Wells, Pass& Seymour/Legrand.NC [M] (All. to C.L. Boynton) CODE-MAKING PANEL NO. 19 Articles 545, 547, 550, 551, 552, 553, 555, 604, 675,Annex D, Examples D11 and D12 Leslie Sabin-Mercado, Chair San Diego Gas& Electric Company.CA[UT] Rep. Electric Light& Power Group/EEI Barry Bauman, Alliant Energy,WI JU] Thomas R.Lichtenstein, Underwriters Laboratories Inc., IL Rep.American Society of Agricultural & Biological [RTJ Engineers Linda J.Little, IBEW Local l Electricians JATC,MO [L] William Bruce Bowman, Fox Systems, Inc.,GA[IM] Rep. International Brotherhood of Electrical Workers Rep. Independent Electrical Contractors, Inc. Timothy P.McNeive, Thomas& Belts Corporation,TN [M] Roger L. Carlson, Monaco Coach Corporation, IN JMJ Rep. National Electrical Manufacturers Association (VL to 550,551,552) John Mikel, Skyline Corporation,IN [M] Monte R.Ewing, Wisconsin Department of Commerce,WI Rep.Manufactured Housing Institute [E] (VL to 550,551.552) Rep. International Association of Electrical Inspectors Tug L.Miller, National Association of RV Parks& James W.Finch, Kampgrounds of America,Inc.,MT[U] Campgrounds,CA[U] (VL to 550,551,552,555) Rep.National Assn.of RV Parks&Campgrounds Bruce A. Hopkins, Recreation Vehicle Industry Association, (VL to 550,551,552) VA IM] Kenneth Weakley, Mountain Electric. Inc.,CA[IM] (VL to 550.551,552) Rep. National Electrical Contractors Association 2008 Edition NATIONAL ELECTRICAL CODE 70-19 NATIONAL ELECTRICAL CODE COMMITTEE Michael L.Zieman, RADCO,CA[RT1 David W.Johnson, CenTex IEC,TX[IM] (VL to 545,550,551,552) (Alt.to W.B.Bowman) Kent Perkins, Recreation Vehicle Industry Association,VA Alternates [M] Glenn H.Ankenbrand, Delmarva Power,MD [UT] (VL to 550,551,552) (Alt.to L.Sabin Mercado) (Alt.to B.A. Hopkins) Michael J. 50 5, P55 Corporation,WT[M] Steven J.Blois, EGS Electrical Group, IL[M] (VL to 550,551,552) (Alt.to T.P. McNeive) (Alt.to J.Mikel) Joseph M.Bolesina, Pinellas County Building Inspections, Raymond F.Tircker, Consulting Professional FL[El Engineer/RADCO,CA[RT] (Alt. to M. R.Ewing) (VL to 545,550,551,552) William(Billy)E.Duggins, San Diego Electrical Training (AIL to M.L.Zieman) Center,CA[L] Eugene W.Wirth, Underwriters Laboratories Inc.,WA[RT] (Alt.to L.L Little) (Alt.to T.R.Lichtenstein) CODE-MAKING PANEL NO. 20 Articles 708 and Annexes F and G Donald P.Bliss, Chair National Infrastructure Institute,NH [Ul Tarry L.Baker, Broward County Board of Rules& Leslie Sabin-Mercado, San Diego Gas&Electric Company, Appeals,FL[El CA IUTI Rep.Intemational Association of Electrical Inspectors Evangelos Stoyas, U.S.Army Corps of Engineers,VA[E] Lawrence A.Bey, Cummins Power Generation.MN [M] Timothy P.Zgonena, Underwriters Laboratories Inc., [L Richard Bingham, Dranetz-BMI, NJ [M] [RT] Jeffrey Boksiner, Telcordia Technologies,Inc.,NJ [UT] Rep.Alliance for Telecommunications Industry Solutions Alternates James C.Carroll, Square D CompmylSchneider Electric, Paul J.Casparro, Scranton Electricians JATC,PA[L] TN IMI (Alt.to P.L.Hickman) Wayne G. Carson, Carson Associates,Inc.,VA[SE) Robert Michael Forister, National Electrical Manufacturers George R.Dauberger, Thomas&Betts Corporation,TN Association,WY[M] IMI (Alt.to G.Moniz) Palmer L.Hickman, National Joint Apprentice&Training Peyton S.Hale,Jr., U.S.Army Corps of Engineers,VA[E] Committee.MD[Ll (Alt. to E.Stoyas) Rep.International Brotherhood of Electrical Workers John R.Kovacik, Underwriters Laboratories Inc., IL[RT1 Ronald A.Keenan, M.C. Dean,Inc.,VA[IMI (Alt.to T.P.Zgonena) Rep.Independent Electrical Contractors,Inc. Alan Manche, Square D Company/Schneider Electric, KY Gil Moniz, National Electrical Manufacturers Association, [M] MA IM] (Alt.to J.C.Carroll) Wayne D.Moore, Hughes Associates,Inc., RI [SE] Stephen V.St.Croix, Primo Electric Company,Inc.,MD Timothy S.Owens, City of Santa Clara,CA[E] [IM] Rep. International Association of Electrical Inspectors (Alt.to R.A.Keenan) NFPA Electrical Engineering Division Technical Staff Mark W.Earley, Assistant Vice President/Chief Electrical Support Staff Engineer Carol Henderson Ernest W.Buss, Senior Electrical Engineer Mary Warren-Pilson Mark Cloutier, Senior Electrical Engineer Kimberly Shea Jean A.O'Connor, Electrical Project SpecialisdSupport NFPA Staff Editors Supervisor Lee F.Richardson, Senior Electrical Engineer Joyce G.Grandy Richard J.Roux, Senior Electrical Specialist Pamela la Nolan Jeffrey S.Sargent, Senior Electrical Specialist Kim Cervantes Joseph V.Sheehan, Principal Electrical Engineer Note: Membership on a committee shall not in and of itself constitute an endorsement of the Association or any document developed by the Committee on which the member serves. Committee Scope: This Committee shall have primary responsibility for documents on minimizing the risk of electricity as a source of electric shock and as a potential ignition source of fires and explosions. It shall also be responsible for text to minimize the propagation of fire and explosions due to electrical installations. 70-20 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 90--INTRODUCTION 90.2 NFPA 70 communications conductors, equipment, and raceways; and National Electrical Code' optical fiber cables and raceways for the following: (1) Public and private premises, including buildings, struc- 2008 Edition tures, mobile homes, recreational vehicles, and floating buildings IMPORTANT NOTE: This NFPA document is made (2) yards, lots, parking lots, carnivals, and industrial available for use subject to important notices and legal substations disclaimers. These notices and disclaimers appear in all • publications containing this document and may be found (3) Installations of conductors and equipment that connect under the heading "Important Notices and Disclaimers to the supply of electricity Concerning NFPA Documents." They can also be ob- (4) Installations used by the electric utility, such as office tained on request from NFPA or viewed at buildings, warehouses, garages, machine shops, and www.nfpa.org/disclaimers. recreational buildings, that are not an integral part of a generating plant, substation, or control center. (B) Not Covered.This Code does not cover the following: ARTICLE 90 (1) Installations in ships, watercraft other than floating Introduction buildings, railway rolling stock, aircraft, or automotive vehicles other than mobile homes and recreational ve- 90.1 Purpose. hicles (A) Practical Safeguarding. The purpose of this Code is FPN: Although the scope of this Code indicates that the the practical safeguarding of persons and property from Code does not cover installations in ships, portions of this Code are incorporated by reference into Title 46, Code of hazards arising from the use of electricity. Federal Regulations, Parts 110-113. (B) Adequacy.This Code contains provisions that are con- (2) Installations underground in mines and self-propelled sidered necessary for safety. Compliance therewith and mobile surface mining machinery and its attendant proper maintenance results in an installation that is essen- electrical trailing cable tially free from hazard but not necessarily efficient, covve- (3) Installations of railways for generation, transformation, nient, or adequate for good service or future expansion of transmission, or distribution of power used exclusively electrical use. for operation of rolling stock or installations used ex- FPN: Hazards often occur because of overloading of wir- clusively for signaling and communications purposes ing systems by methods or usage not in conformity with (4) Installations of communications equipment under the this Code. This occurs because initial wiring did not pro- exclusive control of communications utilities located vide for increases in the use of electricity. An initial ad- outdoors or in building spaces used exclusive) for equate installation and reasonable provisions for system y changes provide. for future increases in the use of such installations electricity. (5) Installations under the exclusive control of an electric (C) Intention.This Code is not intended as a design speci- utility where such installations fication or an instruction manual for untrained persons, a. Consist of service drops or service laterals, and as- (D) Relation to Other International Standards. The re- sociated metering, or quirements in this Code address the fundamental principles b• Are located in legally established easements or of protection for safety contained in Section 131 of Inter- rights-of-way designated by or recognized by public national Electrotechnical Commission Standard 60364-1, service commissions, utility commissions, or other Electrical Installations of Buildings. regulatory agencies having jurisdiction for such in- stallations, or FPN: IEC 60364-1, Section 131, contains fundamental c. Are on property owned or leased by the electric principles of protection for safety that encompass protec- tion against electric shock, protection against thermal ef- fects, protection against overcurrent, protection against generation, control, transformation, transmission, or fault currents, and protection against overvoltage. All of distribution of electric energy. these potential hazards are addressed by the requirements in this Code. FPN to (4) and (5): Examples of utilities may include those entities that are typically designated or recognized by govern- 90.2 Scope. mental law or regulation by public service/utility commissions and that install, operate, and maintain electric supply (such as (A) Covered. This Code covers the installation of electri- generation,transmission,or distribution systems)or communi- cal conductors, equipment, and raceways; signaling and cation systems (such as telephone,CATV,Internet,satellite,or 2009 Edition NATIONAL ELEMICAL CODE 70-21 90.3 ARTICLE 90 INTRODUCTION data services). Utilities may be subject to compliance with 90.4 Enforcement. This Code is intended to be suitable codes and standards covering their regulated activities as for mandatory application by governmental bodies that ex- adopted under governmental law or regulation.Additional in- ercise legal jurisdiction over electrical installations, includ- formation can be found through consultation with the appro- priate governmental bodies, such as state regulatory commis- sions, the Federal Energy Reguiatory Commission, and the insurance inspectors. The authority having jurisdiction for Federal Communications Commission. enforcement of the Code has the responsibility for making interpretations of the rules, for deciding on the approval of (C) Special Permission. The authority having jurisdiction equipment and materials, and for granting the special per- for enforcing this Code may grant exception for the instal- mission contemplated in a number of the rules. lation of conductors and equipment that are not under the By special permission, the authority having jurisdiction exclusive control of the electric utilities and are used to may waive specific requirements in this Code or permit connect the electric utility supply system to the service- alternative methods where it is assured that equivalent ob- entrance conductors of the premises served, provided such jectives can be achieved by establishing and maintaining installations are outside a building or terminate immedi- effective safety. ately inside a building wall. This Code may require new products, constructions, or materials that may not yet be available at the time the Code 90.3 Code Arrangement. This Code is divided into the is adopted. in such event, the authority having jurisdiction introduction and nine chapters, as shown in Figure 90.3. may permit the use of the products, constructions, or mate- Chapters 1, 2, 3, and 4 apply generally; Chapters 5, 6, and 7 rials that comply with the most recent previous edition of apply to special occupancies, special equipment, or other spe- this Code adopted by the jurisdiction. cial conditions.These latter chapters supplement or modify the general rules. Chapters 1 through 4 apply except as amended 90.5 Mandatory Rules, Permissive Rules, and Explana- by Chapters 5, 6, and 7 for the particular conditions. tory Material. Chapter 8 covers communications systems and is not sub- ject to the requirements of Chapters I through 7 except where (A) Mandatory Rules. Mandatory rules of this Code are the requirements are specifically referenced in Chapter 8. those that identify actions that are specifically required or Chapter 9 consists of tables that are applicable as prohibited and are characterized by the use of the terms referenced. shall or shall not. Annexes are not part of the requirements of this Code but are included for informational purposes only. (B) Permissive Rules. Permissive rules of this Code are those that identify actions that are allowed but not required, are normally used to describe options or alternative meth- Chapter 1 —General ods, and are characterized by the use of the terms shall be permitted or shall not be required. Chapter 2—Wiring and Protection Applies generally to all electrical FCh 3—Wiring Methods and Materials installations (C) Explanatory Material. Explanatory material, such as references to other standards, references to related sections Chapter Q—Equipment for General Use of this Code, or information related to a Code rule, is in- cluded in this Code in the form of fine print notes (FPNs). Chapter 5—Special Occupancies Fine print notes are informational only and are not enforce- Supplements or modifies able as requirements of this Code. FP Chapter 6—Special Equipment Brackets containing section references to another NFPA Chapters 1 through 4 g Chapter 7—Special Conditions document are for informational purposes only and are pro- vided as a guide to indicate the source of the extracted text. Chapter 8 is not subject These bracketed references immediately follow the ex- to the requirements of tracted text. Chapters 1 through 7 except Chapter 8—Communications Systems where the requirements are specifically referenced in FPN: The format and language used in this Code follows Chapter 8. guidelines established by NFPA and published in the NEC Chapter 9—Tables }Applicable as referenced Style Manual. Copies of this manual can be obtained from Annex A through Annex H Inlormaltonal only; NFPA. not mandatory 90.6 Formal Interpretations. To promote uniformity of Figure 90.3 Code Arrangement. interpretation and application of the provisions of this 70-22 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 90—INTRODUCTION 90.9 Cade, formal interpretation procedures have been estab- 90.9 Units of Measurement. lished and are found in the NFPA Regulations Governing Committee Projects. (A) Measurement System of Preference.For the purpose of this Code, metric units of measurement are in accor- 90.7 Examination of Equipment for Safety. For specific dance with the modernized metric system known as the items of equipment and materials referred to in this Code, International System of Units (SI). examinations for safety made under standard conditions (B) Dual System of Units. SI units shall appear first, and provide a basis for approval where the record is made gen- inch-pound units shall immediately follow in parentheses. erally available through promulgation by organizations Conversion from inch-pound units to SI units shall be properly equipped and qualified for experimental testing, based on hard conversion except as provided in 90.9(C). inspections of the run of goods at factories, and service- value determination through field inspections. This avoids (C) Permitted Uses of Soft Conversion. The cases given the necessity for repetition of examinations by different in 90.9(C)(I) through (C)(4) shall not be required to use examiners, frequently with inadequate facilities for such hard conversion and shall be permitted to use soft conver- work, and the confusion that would result from conflicting sion, reports on the suitability of devices and materials examined (1) Trade Sizes.Where the actual measured size of a prod- for a given purpose. uct is not the same as the nominal size, trade size designa- It is the intent of this Code that factory-installed inter- tors shall be used rather than dimensions. Trade practices nal wiring or the construction of equipment need not be shall be followed in all cases. inspected at the time of installation of the equipment, ex- (2) Extracted Material. Where material is extracted from cept to detect alterations or damage, if the equipment has another standard, the context of the original material shall been listed by a qualified electrical testing laboratory that is not be compromised or violated. Any editing of the ex- recognized as having the facilities described in the preced- tracted text shall be confined to making the style consistent ing paragraph and that requires suitability for installation in with that of the NEC. accordance with this Code. (3) Industry Practice. Where industry practice is to ex- FPN No. 1: See requirements in 110.3, press units in inch-pound units, the inclusion of SI units FPN No. 2: Listed is defined in Article 100. shall not be required. FPN No. 3: Annex A contains an informative list of prod- (4) Safety. Where a negative impact on safety would re- uct safety standards for electrical equipment. sult, Soft conversion shall be used. 90.8 Wiring Planning. (D) Compliance. Conversion from inch-pound units to SI units shall be permitted to be an approximate conversion. (A) Future Expansion and Convenience. Plans and Compliance with the numbers shown in either the SI sys- specifications that provide ample space in raceways, spare tem or the inch-pound system shall constitute compliance raceways, and additional spaces allow for future increases with this Code. in electric power and communication circuits. Distribution centers located in readily accessible locations provide con- FPN No, l: Hard conversion is considered a change in dimensions or properties of an item into new sizes that venience and safety of operation. might or might not be interchangeable with the sizes used in the original measurement. Soft conversion is considered (B) Number of Circuits in Enclosures. It is elsewhere a direct mathematical conversion and involves a change in provided in this Code that the number of wires and circuits the description of an existing measurement but not in the confined in a single enclosure be varyingly restricted, actual dimension. Limiting the number of circuits in a single enclosure FPN No. 2: SI conversions are based on IEEEIASTM SI minimizes the effects from a short circuit or ground fault 10-1997, Standard for the Use of the International System in one circuit. of Units(SI): The Modern Metric System. 2008 Edition NATIONAL ELECTRICAL CODE 70-23 CHAPTER 1 ARTICLE 100—DEFINITIONS Chapter 1 General can include varying amounts of combustible gases,depend- ARTICLE 100 ing on the askarel type. Definitions Attachment Plug (Plug Cap) (Plug). A device that, by insertion in a receptacle, establishes a connection between Scope.This article contains only those definitions essential the conductors of the attached flexible cord and the conduc- to the proper application of this Code. It is not intended to tors connected permanently to the receptacle. include commonly defined general terms or commonly de- Authority Having Jurisdiction (AHJ). An organization, fined technical terms from related codes and standards. in office, or individual responsible for enforcing the require- general, only those terms that are used in two or more ments of a code or standard, or for approving equipment, articles are defined in Article 100. Other definitions are materials, an installation, or a procedure. included in the article in which they are used but may be referenced in Article 100. FPN: The phrase"authority having jurisdiction," or its ac- Part I of this article contains definitions intended to ronym AM.is used in NFPA documents in a broad manner, apply wherever the terms are used throughout this Code. since jurisdictions and approval agencies vary, as do their responsibilities.Where public safety is primary,the author- Part 11 contains definitions applicable only to the parts of ity having jurisdiction may be a federal, state, local, or articles specifically covering installations and equipment other regional department or individual such as a[ire chief; operating at over 600 volts, nominal. fire marshai;chief of a fire prevention bureau,labor depart- ment, or health department; building official; electrical in- spector; or others having statutory authority. For insurance I. General purposes, an insurance inspection department, rating bureau, or other insurance company representative may be the author- Accessible (as applied to equipment). Admitting close ity having jurisdiction. In many circumstances, the property approach; not guarded by locked doors, elevation, or other owner or his or her designated agent assumes the role of the effective means. authority having jurisdiction; at government installations, the commanding officer or departmental official may be the au- Accessible (as applied to wiring methods). Capable of thority having jurisdiction. being removed or exposed without damaging the building Automatic. Self-acting, operating by its own mechanism structure or finish or not permanently closed in by the struc- when actuated by some impersonal influence, as, for ex- ture or finish of the building. ample, a change in current, pressure, temperature, or me- Accessible, Readily (Readily Accessible). Capable of be- chanical configuration. ing reached quickly for operation, renewal, or inspections Bathroom. An area including a basin with one or more of without requiring those to whom ready access is requisite the following: a toilet, a tub, or a shower. to climb over or remove obstacles or to resort to portable ladders, and so forth. Bonded ()bonding). Connected to establish electrical con- ladders, and conductivity. Ampacity. The current, in amperes, that a conductor can Bonding Jumper. A reliable conductor to ensure the re- carry continuously under the conditions of use without ex- ceeding its temperature rating. quired electrical conductivity between metal parts required to be electrically connected. Appliance. Utilization equipment, generally other than in- Bonding Jumper, Equipment. The connection between dustrial, that is normally built in standardized sizes or types two or more portions of the equipment grounding conduc- and is installed or connected as a unit to perform one or more functions such as clothes washing, air conditioning, tor. food mixing, deep frying, and so forth. Bonding Jumper, Main. The connection between the grounded circuit conductor and the equipment grounding Approved. Acceptable to the authority having jurisdiction. conductor at the service. Askarel. A generic term for a group of nonflammable syn- Branch Circuit. The circuit conductors between the final thetic chlorinated hydrocarbons used as electrical insulating overcurrent device protecting the circuit and the outlet(s). media. Askarels of various compositional types are used. Under arcing conditions, the gases produced, while consist- Branch Circuit,Appliance. A branch circuit that supplies ing predominantly of noncombustible hydrogen chloride, energy to one or more outlets to which appliances are to be 70-24 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 100 DEFINITIONS CHAPTER 1 connected and that has no permanently connected lumi- Setting(of circuit breakers). The value of current,time, or naires that are not a part of an appliance. both, at which an adjustable circuit breaker is set to trip. Branch Circuit, General-Purpose. A branch circuit that Clothes Closet. A non-habitable room or space intended supplies two or more receptacles or outlets for lighting and primarily for storage of garments and apparel. appliances. Communications Equipment. The electronic equipment Branch Circuit, Individual.A branch circuit that supplies that performs the telecommunications operations for the only one utilization equipment. transmission of audio, video, and data, and includes power Branch Circuit, Multiwire. A branch circuit that consists equipment (e.g., do converters, inverters, and batteries) and of two or more ungrounded conductors that have a voltage technical support equipment (e.g., computers). between them, and a grounded conductor that has equal Concealed.]tendered inaccessible by the structure or finish voltage between it and each ungrounded conductor of the of the building. Wires in concealed raceways are consid- circuit and that is connected to the neutral or grounded ered concealed, even though they may become accessible conductor of the system. by withdrawing them. Branch-Circuit OVercurrent DeViee.A device capable of Conductor,Bare. A conductor having no covering or elec- providing protection for Service,feeder,and branch circuits trical insulation whatsoever. and equipment over the full range of overcurrents between its rated current and its interrupting rating. Branch-circuit Conductor, Covered. A conductor encased within material overcurrent protective devices are provided with interrupt- of composition or thickness that is not recognized by this ing ratings appropriate for the intended use but no less than Code as electrical insulation. 5,000 amperes. Conductor, Insulated. A conductor encased within mate- Building. A structure that stands alone or that is cut off rial of composition and thickness that is recognized by this from adjoining structures by fire walls with all openings Code as electrical insulation. therein protected by approved fire doors. Conduit Body. A separate portion of a conduit or tubing Cabinet. An enclosure that is designed for either surface system that provides access through a removable cover(s) mounting or flush mounting and is provided with a frame, to the interior of the system at a junction of two or more mat, or trim in which a swinging door or doors are or can sections of the system or at a terminal point of the system. be hung. Boxes such as FS and FD or larger cast or sheet metal boxes are not classified as conduit bodies. Circuit Breaker. A device designed to open and close a circuit by nonautomatic means and to open the circuit au- Connector, Pressure (Solderless). A device that estab- tomatically on a predetermined overcurrent without damage lishes a connection between two or more conductors or to itself when properly applied within its rating. between one or more conductors and a terminal by means of mechanical pressure and without the use of solder. FPN: The automatic opening means can be integral, direct acting with the circuit breaker, or remote from the circuit Continuous Load. A load where the maximum current is breaker. expected to continue for 3 hours or more. Adjustable (as applied to circuit breakers). A qualifying Controller. A device or group of devices that serves to term indicating that the circuit breaker can be set to trip at govern, in some predetermined manner, the electric power various values of current, time, or both, within a predeter- delivered to the apparatus to which it is connected. mined range. Cooking Unit, Counter-Mounted. A cooking appliance Instantaneous Trip (as applied to circuit breakers). A designed for mounting in or on a counter and consisting of qualifying term indicating that no delay is purposely intro- one or more heating elements, internal wiring, and built-in duced in the tripping action of the circuit breaker. or mountable controls. Inverse Time (as applied to circuit breakers). A qualifying term indicating that there is purposely introduced a delay in Coordination (Selective). Localization of an overcurrent the tripping action of the circuit breaker, which delay de- condition to restrict outages to the circuit or equipment creases as the magnitude of the current increases. affected, accomplished by the choice of overcurrent protec- Nonadjustable {as applied to circuit breakers}. A quali- tive devices and their ratings or settings. fying term indicating that the circuit breaker does not have Copper-Clad Aluminum Conductors. Conductors drawn any adjustment to alter the value of current at which it will from a copper-clad aluminum rod with the copper metallur- trip or the time required for its operation. gically bonded to an aluminum core. The copper forms a 2008 Edition NATIONAL ELECTRICAL CODF 70--25 CHAPTER 1 ARTICLE 100—DEFINITIONS minimum of 10 percent of the cross-sectional area of a electric power to the connected loads, that are external to solid conductor or each strand of a stranded conductor. and not controlled by an interactive System. Cutout Box. An enclosure designed for surface mounting Enclosed. Surrounded by a case, housing, fence, or wall(s) that has swinging doors or covers secured directly to and that prevents persons from accidentally contacting ener- teiescoping with the walls of the box proper. gized parts. Dead Front. Without live parts exposed to a person on the Enclosure. The case or housing of apparatus, or the fence operating side of the equipment. or walls surrounding an installation to prevent personnel Demand Factor. The ratio of the maximum demand of a from accidentally contacting energized parts or to protect the equipment from physical damage. system, or part of a system, to the total connected load of a system or the part of the system under consideration. FPN: See Table 110.20 for examples of enclosure types. Device. A unit of an electrical system that carries or con- Energized. Electrically connected to, or is, a source of trols electric energy as its principal function. voltage. Disconnecting Means. A device, or group of devices, or Equipment. A general term, including material, fittings, other means by which the conductors of a circuit can be devices, appliances, luminaires, apparatus, machinery, and disconnected from their source of supply. the like used as a part of, or in connection with, an electri- Dusttight. Constructed so that dust will not enter the en- cal installation. closing case under specified test conditions. Explosionproof Apparatus. Apparatus enclosed in a case Duty, Continuous. Operation at a substantially constant that is capable of withstanding an explosion of a specified gas or vapor that may occur within it and of preventing the ]and for an indefinitely long time. ignition of a specified gas or vapor surrounding the enclo- Duty, Intermittent. Operation for alternate intervals of(1) sure by sparks, flashes, or explosion of the gas or vapor load and no load; or (2) load and rest; or (3) load, no load, within, and that operates at such an external temperature and rest. that a surrounding flammable atmosphere will not be ig- Duty, Periodic. Intermittent operation in which the load nited thereby. conditions are regularly recurrent. FPN: For further information, see ANSIIUL 1203-1999, Explosion-Proof and Dust-Ignition-Proof.Electrical Equip- Duty, Short-Time. Operation at a substantially constant meat for Use in Hazardous(Classified) Locations. load for a short and definite, specified time. Exposed (as applied to five parts). Capable of being in- Duty, Varying. Operation at loads, and for intervals of advertently touched or approached nearer than a safe dis- time, both of which may be subject to wide variation. tance by a person. It is applied to parts that are not suitably Dwelling, One-Family. A building that consist.,; solely of guarded, isolated, or insulated, one dwelling unit. Exposed (as applied to wiring methods). On or attached Dwelling, Two-Family. A building that consists solely of to the surface or behind panels designed to allow access. two dwelling units. Externally Operable. Capable of being operated without Dwelling, Multifamily. A building that contains three or exposing the operator to contact with live parts. more dwelling units. Feeder. All circuit conductors between the service equip- Dwelling Unit. A single unit, providing complete and in- ment, the source of a separately derived system, or other dependent living facilities for one or more persons, includ- power supply source and the final branch-circuit overcur- rent device. ing permanent provisions for living, sleeping, cooking, and sanitation. Festoon Lighting. A string of outdoor lights that is sus- Electric Sign. A fixed, stationary, or portable self- pended between two points. contained, electrically illuminated utilization equipment Fitting. An accessory such as a locknut, bushing, or other with words or symbols designed to convey information or part of a wiring system that is intended primarily to per- attract attention. form a mechanical rather than an electrical function. Electric Power Production and Distribution Network. Garage.A building or portion of a building in which one or Power production, distribution, and utilization equipment more self-propelled vehicles can be kept for use, sale, stor- and facilities, such as electric utility Systems that deliver age, rental, repair, exhibition, or demonstration purposes. 70--.26 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 100—DEFINITIONS CHAPTER I FPN: For commercial garages, repair and storage, see screens, mats, or platforms to remove the likelihood of ap- Article 511. proach or contact by persons or objects to a point of danger. Ground. The earth. Guest Room. An accommodation combining living, sleep- Grounded (Grounding). Connected (connecting) to ing, sanitary, and storage facilities within a compartment. ground or to a conductive body that extends the ground Guest Suite. An accommodation with two or more con- connection. tiguous rooms comprising a compartment, with or without Grounded, Solidly. Connected to ground without inserting doors between such rooms, that provides living, sleeping, any resistor or impedance device. sanitary, and storage facilities. Grounded Conductor. A system or circuit conductor that Handhole Enclosure. An enclosure for use in underground is intentionally grounded, systems, provided with an open or closed bottom, and sized Ground-Fault Circuit Interrupter (GFCI). A device in- to allow personnel to reach into, but not enter, for the pur- tended for the protection of personnel that functions to de- pose of installing, operating, or maintaining equipment or energize a circuit or portion thereof within an established Firing or both. period of time when a current to ground exceeds the values Hoistway.Any shaftway,hatchway, well hole,or other ver- established for a Class A device. tical opening or space in which an elevator or dumbwaiter FPN: Class A ground-fault circuit interrupters trip when is designed to operate. the current to ground is 6 mA or higher and do not trip when the Current to ground is Iess than 4 mA. For further Identified (as applied to equipment). Recognizable as information, see UL 943, Standard for Ground-Fault Cir- suitable for the specific purpose, function, use, environ- cuit Interrupters. ment, application, and so forth, where described in a par- Ground-Fault Protection of Equipment. A system in- ticular Cade requirement. tended to provide protection of equipment from damaging FPN: Some examples of ways to determine suitability of line-to-ground fault currents by operating to cause a discon- equipment for a specific purpose, environment, or applica- necting means to open all ungrounded conductors of the tion include investigations by a qualified testing laboratory faulted circuit. This protection is provided at current levels (listing and labeling), an inspection agency, or other orga- less than those required to protect conductors from damage nizations concerned with product evaluation. through the operation of a supply circuit overcurrent de- In Sight From (Within Sight From, Within Sight). vice. Where this Cade specifies that one equipment shall be "in Grounding Conductor. A conductor used to connect sight from," "within sight from," or "within sight of," and equipment or the grounded circuit of a wiring system to a so forth, another equipment, the specified equipment is to grounding electrode or electrodes. be visible and not more than 15 m (50 ft) distant from the Grounding Conductor, Equipment (EGC). The conduct other. tive path installed to connect normally non—current- Interactive System. An electric power production system carrying metal parts of equipment together and to the sys- that is operating in parallel with and capable of delivering tem grounded conductor or to the grounding electrode energy to an electric primary source supply system. conductor, or both. Interrupting Rating. The highest current at rated voltage FPN No. 1: It is recognized that the equipment grounding that a device is intended to interrupt under standard test conductor also performs bonding, conditions. FPN No.2: See 250.118 for a list of acceptable equipment grounding conductors. FPN: Equipment intended to interrupt current at other than fault levels may have its interrupting rating implied in other Grounding Electrode. A conducting object through which ratings, such as horsepower or locked rotor current. a direct connection to earth is established. Intersystem Bonding Termination. A device that pro- Grounding Electrode Conductor. A conductor used to vides a means for connecting communications sy$tem(s) connect the system grounded conductor or the equipment to grounding conductor(s) and bonding conductor($) at the a grounding electrode or to a point on the grounding elec- service equipment or at the disconnecting means for build- trode system. ings or structures supplied by a feeder or branch circuit. Guarded. Covered, shielded, fenced, enclosed, or otherwise Isolated (as applied to location). Not readily accessible protected by means of suitable covers, casings, barriers, rails, to persons unless special means for access are used. 2008 Edition NATIONAL ELECTRICAL CODE 70-27 CHAPTER 1 ARTICLE 100—DEFINITIONS Kitchen. An area with a Sink and permanent facilities for Metal-Enclosed Power Switchgear. A switchgear assem- food preparation and cooking. bly completely enclosed on all sides and top with sheet Labeled. Equipment or materials to which has been at- metal (except for ventilating openings and inspection win- tached a label, symbol, or other identifying mark of an dows) and containing primary power circuit switching, in- terrupting devices, or both, with buses and connections. organization that is acceptable to the authority having juris- The assembly may include control and auxiliary devices. diction and concerned with product evaluation, that main- tains periodic inspection of production of labeled equip- Access to the interior of the enclosure is provided by doors,ment or materials, and by whose labeling the manufacturer removable covers, or both. Metal-enclosed power switch- indicates compliance with appropriate standards or per-for- gear is available in non-arc-resistant or are-resistant co°- mance in a specified manner. structions. Lighting Outlet. An outlet intended for the direct connec- Motor Control Center. An assembly of one or more en- tion of a lampholder or luminaire. closed sections having a common power bus and princi- pally containing motor control units. Listed. Equipment, materials, or services included in a list published by an organization that is acceptable to the au- Multioutlet Assembly. A type of surface, Hush, or free- thority having jurisdiction and concerned with evaluation standing raceway designed to hold conductors and recep- of products or services, that maintains periodic inspection tacles, assembled in the field or at the factory. of production of listed equipment or materials or periodic evaluation of services, and whose listing states that either Neutral Conductor. The conductor connected to the neu- the equipment, material, or service meets appropriate des- or point of a system that i5 intended to carry current under n ignated standards or has been tested and found suitable for normal conditions. a specified purpose. Neutral Point.The common point on a wye-connection in FPN: The means for identifying listed equipment may vary a polyphase system or midpoint on a Single-phase, 3-wire for each organization concerned with product evaluation, system, or midpoint of a single-phase portion of a 3-phase some of which do not recognize equipment as listed unless delta system, or a midpoint of a 3-wire, direct-current it is also labeled.Use of the system employed by the listing System. organization allows the authority having jurisdiction to identify a listed product. FPN: At the neutral point of the system,the vectorial sum Live Parts. Energized conductive components. of the nominal voltages from all other phases within the system that utilize the neutral, with respect to the neutral Location, Damp. Locations protected From weather and point,is zero potential. not subject to saturation with water or other liquids but Nonautomatic. Action requiring personal intervention for subject to moderate degrees of moisture. Examples of such its control. As applied to an electric controller, nonauto- locations include partially protected locations under cano- matic control does not necessarily imply a manual control- pies, marquees, roofed open porches, and like locations, ler, but only that personal intervention is necessary. and interior locations subject to moderate degrees of mois- ture, such as some basements, some barns, and some cold- Nonlinear Load. A load where the wave shape of the storage warehouses. steady-state current does not follow the wave shape of the Location, Dry. A location not normally subject to damp- applied voltage. ness or wetness. A location classified as dry may be tem- FPN: Electronic equipment, electronic/electric-discharge porarily subject to dampness or wetness, as in the case of a lighting,adjustable-speed drive systems,and similar equip- building under construction. ment may be nonlinear loads. Location, Wet. Installations underground or in concrete Outlet. A point on the wiring system at which current is slabs or masonry in direct contact with the earth; in loca- taken to supply utilization equipment. tions subject to saturation with water or other liquids, such as vehicle washing areas; and in unprotected locations ex- Outline Lighting. An arrangement of incandescent lamps, posed to weather, electric-discharge lighting, or other electrically powered light sources to outline or call attention to certain features Luminaire. A complete lighting unit consisting of a light such as the shape of a building or the decoration of a Source Such as a lamp or lamps, together With the parts window. designed to position the light source and connect it to the power supply. It may also include parts to protect the light Overcurrent. Any current in excess of the rated current of Source or the ballast or to distribute the light.A lampholder equipment or the ampacity of a conductor. It may result itself is not a luminaire. from overload, short circuit, or ground fault. 70--.28 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 100—DEFINITIONS CHAPTER 1 FPN: A current in excess of rating may be accommodated concrete floor raceways, cellular metal floor raceways, by certain equipment and conductors for a given set of surface raceways, wireways, and busways. conditions. Therefore, the rules for overcurrent protection are specific for particular situations. Rainproof. Constructed, protected, or treated so as to pre- Overload. Operation of equipment in excess of normal, vent rain from interfering with the successful operation of full-load rating, or of a conductor in excess of rated ampac- the apparatus under specified test conditions. ity that, when it persists for a sufficient length of time, Raintight. Constructed or protected so that exposure to a would cause damage or dangerous overheating. A fault, beating rain will not result in the entrance of water under such as a short circuit or ground fault, is not an overload. specified test conditions. Panelboard. A single panel or group of panel units de- Receptacle.A receptacle is a contact device installed at the signed for assembly in the form of a single panel,including outlet for the connection of an attachment plug. A single buses and automatic overcurrent devices, and equipped receptacle is a single contact device with no other contact with or without switches for the control of light, heat, or device on the same yoke. A multiple receptacle is two or power circuits; designed to be placed in a cabinet or cutout more contact devices on the same yoke. box placed in or against a wall, partition, or other support; Receptacle Outlet. An outlet where one or more rece and accessible only from the front. tacles are installed. p Plenum. A compartment or chamber to which one or more Remote-Control Circuit. Any electrical circuit that con- air ducts are connected and that forms part of the air distri- trols any other circuit through a relay or an equivalent de- bution system. vice. Power Outlet. An enclosed assembly that may include re- Sealable Equipment. Equipment enclosed in a case or ceptacles, circuit breakers, fuseholders, fused switches, cabinet that is provided with a means of sealing or locking buses, and watt-hour meter mounting means; intended to so that live parts cannot be made accessible without open- supply and control power to mobile homes, recreational ing the enclosure. The equipment may or may not be oper- vehicles, park trailers, or boats or to serve as a means for able without opening the enclosure. distributing power required to operate mobile or tempo- rarily installed equipment. Separately Derived System. A premises wiring system whose power is derived from a source of electric energy or Premises Wiring (System}, Interior and exterior wiring, equipment other than a service. Such systems have no di- including power, lighting, control, and signal circuit wiring rect electrical connection, including a solidly connected together with all their associated hardware, fittings, and grounded circuit conductor, to supply conductors originat- wiring devices,both permanently and temporarily installed. ing in another system. This includes (a) wiring from the service point or power source to the outlets or (b) wiring from and including the Service.The conductors and equipment for delivering elec- power source to the outlets where there is no service point. tric energy from the serving utility to the wiring system of Such wiring does not include wiring internal to appli- the premises served. antes, luminaires, motors, controllers, motor control cen- Service Cable. Service conductors made up in the form of ters, and similar equipment. a cable. Qualified Person. One who has skills and knowledge re- Service Conductors. The conductors from the service lated to the construction and operation of the electrical point to the service disconnecting means. equipment and installations and has received safety training to recognize and avoid the hazards involved. Service Drop. The overhead service conductors from the last pole or other aerial support to and including the splices, FPN: Refer to NFPA 70E®-2004, Standard far Electrical if any, connecting to the service-entrance conductors at the Safety in the Workplace, for electrical safety training building or other structure. requirements. Raceway. An enclosed channel of metal or nonmetallic Service-Entrance Conductors, Overhead System. The service conductors between the terminals of the service materials designed expressly for holding wires, cables, or 6usbars, with additional functions as permitted in this equipment and a point usually outside the building, clear of Cade. Raceways include, but are not limited to, rigid metal building walls, where joined by tap or splice to the service drop.conduit, rigid nonmetallic conduit, intermediate metal con- duit, liquidtight flexible conduit, flexible metallic tubing, Service-Entrance Conductors, Underground System. flexible metal conduit, electrical nonmetallic tubing, The service conductors between the terminals of the service electrical metallic tubing, underfloor raceways, cellular equipment and the point of connection to the service lateral. 2008 Edition NATIONAL ELECTRICAL CODE 70.29 CHAPTER 1 ARTICLE 100—DEFINITIONS FPN: Where service equipment is located outside the current; fit also prevents continued flow of follow cutarent building walls, there may be no service-entrance conduc- While remaining capable of repeating these functions and is tors or they may be entirely outside the building. designated as follows: Service Equipment. The necessary equipment, usually Type 1: Permanently connected SPDs intended for in- consisting of a circuit breaker(s) or switch(es) and fuse(s) stallation between the secondary of the service transformer and their accessories, connected to the load end of service and the line side of the Service disconnect overcurrent conductors to a building or other structure, or an otherwise device. designated area, and intended to constitute the main control Type 2: Permanently connected S'PDs intended for in- and cutoff of the supply. Stallation on the load side of the service disconnect over- current device,including SPDs located at the branch panel. Service Lateral. The underground service conductors be- Type 3: Point of utilization SPDs. tween the street main, including any risers at a pole or other 'Type 4: Component SPDs, including discrete compo- structure or from transformers, and the first point of con- nents, as well as assemblies. nection to the service-entrance conductors in a terminal box or meter or other enclosure, inside or outside the building FPN: For further information on Type 1,Type 2,Type 3, wall. Where there is no terminal box, meter, or other enclo- and Type 4 SPDs,see LJL 1449, Standard for Surge Pro- sure, the point of connection is considered to be the point of tective Devices. entrance of the service conductors into the building. Switch, Bypass Isolation. A manually operated device Service Point. The point of connection between the facili- used in conjunction with a transfer switch to provide a ties of the serving utility and the premises wiring. means of directly connecting load conductors to a power source and of disconnecting the transfer switch. Short-Circuit Current Rating.The prospective symmetri- cal fault current at a nominal voltage to which an apparatus Switch, General-Use.A switch intended for use in general or system is able to be connected without sustaining dam- distribution and branch circuits. It is rated in amperes, and age exceeding defined acceptance criteria. it is capable of interrupting its rated current at its rated voltage. Show Window. Any window used or designed to be used for the display of goods or advertising material, whether it Switch, General-Use Snap. A form of general-use switch is fully or partly enclosed or entirely open at the rear and constructed so that it can be installed in device boxes or on whether or not it has a platform raised higher than the street box covers, or otherwise used in conjunction with wiring floor level. systems recognized by this Code. Signaling Circuit. Any electrical circuit that energizes sig- Switch, Isolating. A switch intended for isolating an elec- naling equipment. trical circuit from the source of power. It has no interrupt- ing rating, and it is intended to be operated only after the Solar Photovoltaic System.The total components and sub- circuit has been opened by some other means. systems that, in combination, convert solar energy into electric energy suitable for connection to a utilization load. Switch, Motor-Circuit. A switch rated in horsepower that is capable of interrupting the maximum operating overload Special Permission. The written consent of the authority current of a motor of the same horsepower rating as the having jurisdiction, switch at the rated voltage. Structure. That which is built or constructed. Switch,Transfer.An automatic or nonautomatic device for Supplementary Overcurrent Protective Device. A device transferring one or more load conductor connections from intended to provide limited overcurrent protection for spe- one power source to another. cific applications and utilization equipment such as lumi- Switchboard. A large single panel, frame, or assembly of naires and appliances. This limited protection is in addition to the protection provided in the required branch circuit by panels on which are mounted on the face, back, or both, the branch circuit overcurrent protective device. switches, overcurrent and other protective devices, buses, and usually instruments. Switchboards are generally acces- Surge Arrester.A protective device for limiting surge volt- sible from the rear as well as from the front and are not ages by discharging or bypassing surge current; it also pre- intended to be installed in cabinets. vents continued flow of follow current while remaining ca- pable of repeating these functions. Thermally Protected (as applied to motors). The words Thermally Protected appearing on the nameplate of a motor Surge-Protective Device (SPD). A protective device for or motor-compressor indicate that the motor is provided limiting transient voltages by diverting or limiting surge with a thermal protector. 70-30 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 100—DEFINITIONS CHAPTER 1 Thermal Protector (as applied to motors). A protective FPN: Rainproof,raintight,or watertight equipment can ful- device for assembly as an integral part of a motor or motor- fill the requirements for weatherproof where varying compressor that, when properly applied, protects the motor weather conditions other than wetness, such as snow, ice, against dangerous overheating due to overload and failure dust, or temperature extremes, are not a factor. to start. FPN: The thermal protector may consist of one or more II. Over 600 Volts, Nominal sensing elements integral with the motor or motor- Whereas the preceding definitions are intended to apply compressor and an external control device. wherever the terms are used throughout this Code, the fol- lowing definitions are applicable only to parts of the article Ungrounded. Not connected to ground or to a conductive specifically covering installations and equipment operating body that extends the ground connection. at over 600 volts, nominal. Utility-Interactive Inverter. An inverter intended for use Electronically Actuated Fuse. An overcurrent protective in parallel with an electric utility to supply common loads device that generally consists of a control module that pro- that Array deliver power to the utility. vides current sensing, electronically derived time—current Utilization Equipment. Equipment that utilizes electric characteristics, energy to initiate tripping, and an interrupt- energy for electronic,electromechanical, chemical, heating, ing module that interrupts current when an overcurrent oc- lighting, or similar purposes. curs. Electronically actuated fuses may or may not operate in a current-limiting fashion, depending on the type of con- Ventilated. Provided with a means to permit circulation of trol selected. air sufficient to remove an excess of heat, fumes, or vapors. Fuse. An overcurrent protective device with a circuit- Volatile Flammable Liquid. A flammable liquid having a opening fusible part that is heated and severed by the pas- flash point below 38°C (100°F), or a flammable liquid sage of overcurrent through it. whose temperature is above its flash point, or a Class II combustible liquid that has a vapor pressure not exceeding FPN: A fuse comprises all the parts that form a unit ca- 276 kPa (40 psia) at 38°C (100°F) and whose temperature pable of performing the prescribed functions.It may or may not be the complete device necessary to connect it into an is above its flash point. electrical circuit. Voltage(of a circuit).The greatest root-mean-square(rms) Controlled Vented Power Fuse. A fuse with provision for (effective) difference of potential between any two conduc- controlling discharge circuit interruption such that no solid tors of the circuit concerned. material may be exhausted into the surrounding atmo- FPN: Some systems, such as 3-phase 4-wire, single-phase sphere. 3-wire,and 3-wire direct current, may have various circuits FPN; The fuse is designed so that discharged gases will not of various voltages. ignite or damage insulation in the path of the discharge Voltage, Nominal. A nominal value assigned to a circuit or or propagate a flashover to or between grounded mem- bers or conduction members in the path of the discharge system for the purpose of conveniently designating its volt- where the distance between the vent and such insulation age class (e.g., 120/240 volts, 480Y/277 volts, 600 volts). or conduction members conforms to manufacturer's The actual voltage at which a circuit operates can vary from recommendations. the nominal within a range that permits satisfactory opera- Expulsion Fuse Unit(Expulsion Fuse). A vented fuse unit tion of equipment. in which the expulsion effect of gases produced by the are FPN: See ANSI C84.1-2006, Voltage Ratings for Electric and lining of the fuseholder, either alone or aided by a Power Systems and Equipment(60 Hz). spring, extinguishes the arc. Voltage to Ground. For grounded circuits, the voltage be- Nonvented Power Fuse. A fuse without intentional provi- tween the given conductor and that point or conductor of sion for the escape of arc gases, liquids, or solid particles to the circuit that is grounded; for ungrounded circuits, the the atmosphere during circuit interruption. greatest voltage between the given conductor and any other Power Fuse Unit, A vented, nonvented, or controlled conductor of the circuit. vented fuse unit in which the arc is extinguished by being drawn through solid material, granular material, or liquid, Watertight.Constructed so that moisture will not enter the either alone or aided by a spring. enclosure under specified test conditions. Vented Power Fuse. A fuse with provision for the escape Weatherproof. Constructed or protected so that exposure of arc gases, liquids, or solid particles to the surrounding to the weather will not interfere with successful operation. atmosphere during circuit interruption. 2008 Edition NATIONAL ELECTRICAL CODE 70-31 110.1 ARTICLE 110—REQUIREMENTS FOR ELECTRICAL INSTALLATIONS Multiple Fuse. An assembly of two or more single-pole FPN: See 90.7, Examination of Equipment for Safety, and fuses. 110.3, Examination, Identification, Installation, and Use of Equipment. See definitions of Approved, Identified, La- Switching Device. A device designed to close, open, or beled, and Listed. both, one or more electrical circuits. A switching device capable of making, Circuit Breaker. 110.3 Examination, Identification, Installation, and Use of Equipment. carrying, and interrupting currents under normal circuit conditions, and also of making, carrying for a specified (A) Examination, In judging equipment, considerations time, and interrupting currents under specified abnormal such as the following shall be evaluated: circuit conditions, such as those of short circuit. (1) Suitability for installation and use in conformity with Cutout. An assembly of a fuse support with either a fuse- the provisions of this Code holder, fuse carrier, or disconnecting blade. The fuseholder FPN: Suitability of equipment use may be identified by a or fuse carrier may include a conducting element(fuse link) description marked on or provided with a product to iden- or may act as the disconnecting blade by the inclusion of a tify the suitability of the product for a specific purpose, nonfusible member. environment, or application. Suitability of equipment may he evidenced by listing or labeling. Disconnecting Means. A device, group of devices, or other means whereby the conductors of a circuit can be (2) Mechanical strength and durability, including, for parts designed to enclose and protect other equipment, the disconnected from their source of supply. adequacy of the protection thus provided Disconnecting (or Isolating) Switch (Disconnecter, Isola- (3) Wire-bending and connection space tor). A mechanical switching device used for isolating a (4) Electrical insulation circuit or equipment from a source of power. (5) Heating effects under normal conditions of use and also Interrupter Switch, A switch capable of making, carrying, under abnormal conditions likely to arise in service and interrupting specified currents. (6) Arcing effects Oil Cutout (Oil-Filled Cutout). A cutout in which all or (7) Classification by type, size, voltage, current capacity, part of the fuse support and its fuse link or disconnecting and specific use blade is mounted in oil with complete immersion of the (8) Other factors that contribute to the practical safeguard- contacts and the fusible portion of the conducting element ing of persons using or likely to come in contact with (fuse link) so that arc interruption by severing of the fuse the equipment link or by opening of the contacts will occur under oil. Oil Switch. A switch having contacts that operate under oil (B) Installation and Use. Listed or labeled equipment (or askarel or other suitable liquid). shall be installed and used in accordance with any instruc- tions included in the listing or labeling. Regulator Bypass Switch. A specific device or combina- tion of devices designed to bypass a regulator. 110.4 Voltages. Throughout this Code, the voltage consid- ered shall be that at which the circuit operates. The voltage rating of electrical equipment shall not be less than the nominal voltage of a circuit to which it is connected. ARTICLE 110 110.5 Conductors.Conductors normally used to carry cur- Requirements for Electrical Installations rent shall be of copper unless otherwise provided in this Code. Where the conductor material is not specified, the I. General material and the sizes given in this Code shall apply to copper conductors.Where other materials are used, the size 110.1 Scope. This article covers general requirements for shall be changed accordingly. the examination and approval, installation and use, access FPN: For aluminum and copper-clad aluminum conduc- to and spaces about electrical conductors and equipment; tors, see 310.15. enclosures intended for personnel entry; and tunnel instal- lations. 110.6 Conductor Sizes. Conductor sizes are expressed in American Wire Gage (AWG) or in circular mils. 110.2 Approval. The conductors and equipment required or permitted by this Code shall be acceptable only if 110.7 Wining Integrity. Completed wiring installations approved. shall be free from short circuits, ground faults, Or any 70-32 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 110--REQUIREMENTS FOR ELECTRICAL INSTALLATIONS 110.14 connections to ground other than as required or permitted (A) Unused Openings. Unused openings, other than those eI5eWhere in this Code. intended for the operation of equipment,those intended for mounting purposes, or those permitted as part of the design 110.8 Wiring Methods. Only wiring methods recognized for listed equipment, shall be closed to afford protection as suitable are included in this Code.The recognized meth- substantially equivalent to the wall of the equipment. ods of wiring shall be permitted to be installed in any type Where metallic plugs or plates are used with nonmetallic of building or occupancy, except as otherwise provided in enclosures, they shall be recessed at least 6 mm (1/a in.) this Cade. from the outer surface of the enclosure. 110.9 Interrupting Rating, Equipment intended to inter- (B) Integrity of Electrical Equipment and Connections. rupt current at fault levels shall have an interrupting rating Internal parts of electrical equipment, including busbars, sufficient for the nominal circuit voltage and the current wiring terminals, insulators, and other surfaces, shall not be that is available at the line terminals of the equipment. damaged or contaminated by foreign materials such as Equipment intended to interrupt current at other than fault paint, plaster, cleaners, abrasives, or corrosive residues. levels shall have an interrupting rating at nominal circuit volt- There shalt be no damaged parts that may adversely affect age sufficient for the current that must be interrupted. safe operation or mechanical strength of the equipment such as parts that are broken; bent; cut; or deteriorated by 110.10 Circuit Impedance and Other Characteristics. corrosion, chemical action, or overheating. The overcurrent protective devices, the total impedance, the component short-circuit current ratings, and other charac- 110.13 Mounting and Cooling of Equipment. teristics of the circuit to be protected shall be selected and coordinated to permit the circuit-protective devices used to (A) Mounting. Electrical equipment shall be firmly se- cured to the surface on which it is mounted. Wooden plugs clear a fault to do so without extensive damage to the elec- driven into holes in masonry, concrete, plaster, or similar trical components of the circuit.This fault shall be assumed materials shall not be used, to be either between two or more of the circuit conductors or between any circuit conductor and the grounding con- (B) Cooling. Electrical equipment that depends on the ductor or enclosing metal raceway. Listed products applied natural circulation of air and convection principles for cool- in accordance with their listing shall be considered to meet ing of exposed surfaces shall be installed so that room the requirements of this section, airflow over such surfaces is not prevented by walls or by adjacent installed equipment. For equipment designed for 110.11 Deteriorating Agents. Unless identified for use in floor mounting, clearance between top surfaces and adja- the operating environment, no conductors or equipment cent surfaces shall be provided to dissipate rising warm air. shall be located in damp or wet locations;where exposed to Electrical equipment provided with ventilating openings gases, fumes, vapors, liquids, or other agents that have a shall be installed so that walls or other obstructions do not deteriorating effect on the conductors or equipment; or prevent the free circulation of air through the equipment. where exposed to excessive temperatures. FPN No. 1: See 300.6 for protection against corrosion. 110.14 Electrical Connections. Because of different char- acteristics of dissimilar metals, devices such as pressure FPN No. 2: Some cleaning and lubricating compounds can cause severe deterioration of many plastic materials used terminal or pressure splicing connectors and soldering lugs for insulating and structural applications in equipment. shall be identified for the material of the conductor and shall be properly installed and used. Conductors of dissimi- Equipment not identified for outdoor use and equipment lar metals shall not be intermixed in a terminal or splicing identified only for indoor use,such as "dry locations,""in- connector where physical contact occurs between dissimilar door use only," "damp Iocations," or enclosure Types 1, 2, conductors (such as copper and aluminum, copper and 5, 12, 12K, andlor 13, shall be protected against permanent copper-clad aluminum, or aluminum and copper-clad alu- damage from the weather during building construction. minum), unless the device is identified for the purpose and FPN No. 3: See Table 110.20 for appropriate enclosure-type conditions of use. Materials such as solder, fluxes, inhibi- designations. tors, and compounds, where employed, shall be suitable for the use and shall be of a type that will not adversely affect 110.12 Mechanical Execution of Work. Electrical equip- the conductors, installation, or equipment. ment shall be installed in a neat and workmanlike manner. FPN: Many terminations and equipment are marked with a FPN: Accepted industry practices are described in tightening torque. ANSYNECA 1-2006, Standard Practices for Good Work- manship in Electrical Contracting, and other ANSI- (A) Terminals. Connection of conductors to terminal approved installation standards. parts shall ensure a thoroughly good connection without 2008 Edition NATIONAL ELECTRICAL CODE 70-33 110.I5 ARTICLE 110—REQUIREMENTS FOR ELECTRICAL INSTALLATIONS damaging the conductors and shall be made by means of (1) Conductors rated 75°C (167°F) pressure connectors (including set-screw type), solder (2) Conductors with higher temperature ratings, provided lugs, or splices to flexible leads. Connection by means of the ampacity of such conductors does not exceed the wire-binding screws or studs and nuts that have upturned 75°C (167°F) ampacity of the conductor size used, or lugs or the equivalent shall be permitted for 10 AWG or up to their ampacity if the equipment is listed and iden- smaller conductors. tified for use with such conductors Terminals for more than one conductor and terminals used to connect aluminum shall be so identified. (2) Separate Connector Provisions. Separately installed pressure connectors shall be used with conductors at the (B) Splices. Conductors shall be spliced or joined with ampacities not exceeding the ampacity at the listed and splicing devices identified for the use or by brazing, weld- identified temperature rating of the connector. ing, or soldering with a fusible metal or alloy. Soldered FPN: With respect to 110.14(C)(1) and (C)(2), equipment splices shall first be spliced or joined so as to be mechani- markings or listing information may additionally restrict cally and electrically secure without solder and then be the sizing and temperature ratings of connected conductors. soldered.All splices and joints and the free ends of conduc- tors shall be covered with an insulation equivalent to that of 110.15 High-Leg Marking. On a 4-wire, delta-connected the conductors or with an insulating device identified for system where the midpoint of one phase winding is the purpose. grounded, only the conductor or busbar having the higher Wire connectors or splicing means installed on conduc- phase voltage to ground shall be durably and permanently tors for direct burial shall be listed for such use. marked by an outer finish that is orange in color or by other effective means. Such identification shall be placed at each (C) Temperature Limitations. The temperature rating as- point on the system where a connection is made if the sociated with the ampacity of a conductor shall be selected grounded conductor is also present. and coordinated so as not to exceed the lowest temperature rating of any connected termination, conductor, or device. 110.16 Flash Protection. Electrical equipment, Such as Conductors with temperature ratings higher than specified switchboards, panelboards, industrial control panels, meter for terminations shall be permitted to be used for ampacity socket enclosures, and motor control centers, that are in adjustment, correction, or both, other than dwelling occupancies, and are likely to require (1) Equipment Provisions. The determination of termina- examination, adjustment, servicing, or maintenance while tion provisions of equipment shall be based on energized shall be field marked to warn qualified persons of 110.14(C)(1)(a) or(C)(1)(b). Unless the equipment is listed potential electric arc flash hazards. The marking shall be and marked otherwise, conductor ampacities used in deter- located so as to be clearly visible to qualified persons be- mining equipment termination provisions shall be based on fore examination, adjustment, servicing, or maintenance of Table 310.16 as appropriately modified by 310.15(B)(6). the equipment. (a) Termination provisions of equipment for circuits FPN No. 1: NFPA 70E-2004, Standard for Electrical Safety in the Workplace,provides assistance in determining rated 100 amperes or less, or marked for 14 AWG through severity of potential exposure, planning safe work prac- 1 AWG conductors, shall be used only for one of the fol- tices, and selecting personal protective equipment. lowing: FPN No. 2: ANSI Z535.4-1998,Product Safety Signs and (t) Conductors rated 60°C (140 11F). Labels, provides guidelines for the design of safety signs (2) Conductors with higher temperature ratings, provided and labels for application to products. the ampacity of such conductors is determined based on the 60°C (140°F) ampacity of the conductor size 110.18 Arcing Parts. Parts of electrical equipment that in used. ordinary operation produce arcs, sparks, flames, or molten (3) Conductors with higher temperature ratings if the metal shall be enclosed or separated and isolated from all equipment is listed and identified for use with such combustible material. conductors. FPN: For hazardous(classified)locations, see Articles 500 (4) For motors marked with design letters B, C. or D, con- through 517. For motors, see 430.14. ductors having an insulation rating of 75°C (167°F) or higher shall be permitted to be used, provided the am- 110.19 Light and Power from Railway Conductors.Cir- pacity of such conductors does not exceed the 75°C cuits for lighting and power shall not be connected to any (167°F) ampacity. system that contains trolley wires with a ground return. (b) Termination provisions of equipment for circuits Exception: Such circuit connections shall be permitted in rated over 100 amperes, or marked for conductors larger car houses,power houses, or passenger and freight stations than I AWG, shall be used only for one of the following: operated in connection with electric railways. 70-34 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 110—REQUIREMENTS FOR ELECTRICAL INSTALLATIONS 110.21 110.20 Enclosure Types.Enclosures(other than surround- (classified) locations. The enclosures are not intended to ing fences or walls) of switchboards, panelboards, indus- protect against conditions such as condensation,icing, cor- trial control panels, motor control centers, meter sockets, rosion, or contamination that May occur within the enclo- and motor controllers,rated not over 600 volts nominal and sure or enter via the conduit or unsealed openings. intended for such locations, shall be marked with an enclosure-type number as shown in Table 110.20. 110.21 Marking. The manufacturer's name, trademark, Table 110.20 shall be used for selecting these enclo- or other descriptive marking by which the organization sures for use in specific locations other than hazardous Table 110.20 Enclosure Selection Provides a Degree of For Outdoor Use Protection Against the Enclosure-Type Number Following Environmental Conditions 3 3R 3S 3X 3RX 3SX 4 4X 6 6P Incidental contact with the X X X X X X X X X X enclosed equipment Rain, snow, and sleet X X X X X X X X X X Sleet* — — X — — X — — — Windblown dust X — X X — X X X X X Hosedown — — — — — — X X X X Corrosive agents — — X X X — X — X Temporary submersion — — — — — -- — -- X X Prolonged submersion — — — — — -- — — — X Provides a Degree of For Indoor Use Protection Against the Enclosure-Type Number Following Environmental Conditions 1 2 4 4X 5 6 6P 12 12K 13 Incidental contact with the X X X X X X X X X X enclosed equipment Falling dirt X X X X X X X X X X Falling liquids and light — X X X X X X X X X splashing Circulating dust, lint, fibers, — — X X — X X X X X and Hyings Settling airborne dust, lint, — X X X X X X X X fibers, and flyings Hosedown and splashing — — X X — X X — — — water Oil and coolant seepage — — — — — — — X X X Oil or coolant spraying and X splashing Corrosive agents — — — X — — X — — -- Temporary submersion — — -- — — X X — — Prolonged submersion — — — — — — x — — *Mechanism shall be operable when ice covered. FPN:The term raintight is typically used in conjunction with Enclosure Types 3, 3S, 3SX,3X,4,4X, 6, and 6R The term rainproof is typically used in conjunction with Enclosure Types 3R,and 3RX.The tern tivarertighr is typically used in conjunction with Enclosure Types 4,4X, 6, 6P. The tern driptight is typically used in conjunction with Enclosure Types 2,5, 12. 12K,and 13.The term dusttight is typically used in conjunction with Enclosure Types 3. 3S, 3SX, 3X, 5, 12, 12K, and 13. 2008 Edition NATIONAL ELECTRICAL CODE 70-35 H0.22 ARTICLE l 10—REQUIREMENTS FOR ELECTRICAL INSTALLATIONS responsible for the product can be identified shall be while energized shall comply with the dimensions of placed on all electrical equipment. Other markings that I I0.26(A)(1),(A)(2),and(A)(3)or as required or permitted indicate voltage, current, wattage, or other ratings shall elsewhere in this Code. be provided as specified elsewhere in this Code. The (1) Depth of Working Space. The depth of the working marking shall be of sufficient durability to withstand the space in the direction of live parts shall not be less than that environment involved. specified in Table 110.26(A)(1) unless the requirements of 110.22 Identification of Disconnecting Means. 110.26(A)(1)(a), (A)(1)(b), or (A)(1)(c) are met. Distances shall be measured from the exposed live parts or from the (A) General. Each disconnecting means shall be legibly enclosure or opening if the live parts are enclosed. marked to indicate its purpose unless located and arranged so the purpose is evident.The marking shall be of sufficient durability to withstand the environment involved. Table 110.26(A)(1) Working Spaces (B) Engineered Series Combination Systems.Where cir- Nominal Minimum Clear Distance cuit breakers or fuses are applied in compliance with series Voltage to combination ratings selected under engineering supervision Ground Condition 1 Condition 2 Condition 3 and marked on the equipment as directed by the engineer, 0-150 914 mm (3 ft) 914 mm (3 ft) 914 mm (3 ft) the equipment enclosure(s) shall be legibly marked in the 151-600 914 mm (3 ft) 1.07 m(3 ft 6 in.) 1.22 m (4 ft) field to indicate the equipment has been applied with a series combination rating.The marking shall be readily vis- Note:Where the conditions are follows: Condition I —Exposed live parts on one side of the working space ible and State the following: and no live or grounded parts on the other side of the working space, CAUTION -- ENGINEERED SERIES COMBINA- or exposed live parts on both sides of the working space that are effectively guarded by insulating materials. TION SYSTEM RATED AMPERES. IDENTI- Condition 2—Exposed live parts on one side of the working space FIED REPLACEMENT COMPONENTS REQUIRED. and grounded parts on the other side of the working space. Concrete, brick,or tile walls shall be considered as grounded. FPN: See 240,86(A) for engineered Series combination Condition 3 — Exposed live parts on both sides of the working systems. space. (C) Tested Series Combination Systems. Where circuit breakers or fuses are applied in compliance with the series (a) Dead-Front Assemblies. Working space shall not be combination ratings marked on the equipment by the manu- required in the back or sides of assemblies, such as dead- facturer, the equipment enclosure(s) shall be legibly front switchboards or motor control centers, where all con- marked in the field to indicate the equipment has been nections and all renewable or adjustable parts,such as fuses applied with a series combination rating.The marking shall or switches, are accessible from locations other than the be readily visible and state the following: back or sides. Where rear access is required to work on CAUTION — SERIES COMBINATION SYSTEM nonelectrical parts on the back of enclosed equipment, a RATED AMPERES. IDENTIFIED REPLACEMENT minimum horizontal working space of 762 mm (30 in.) COMPONENTS REQUIRED. shall be provided. (b) Low Voltage. By special permission, smaller work- FPN: See 240.86(B)for tested series combination systems, ing Spaces shall be pennitted where all exposed live parts operate at not greater than 30 volts rms, 42 volts peak, or 110.23 Current Transformers. Unused current transform- 60 volts dc. ers associated with potentially energized circuits shall be (c) Existing Buildings. In existing buildings where short-circuited. electrical equipment is being replaced,Condition 2 working clearance shall be permitted between dead-front switch- 11. 600 Volts, Nominal, or Less boards, panelboards, or motor control centers located across the aisle from each other where conditions of main- 110.26 Spaces About Electrical Equipment. Sufficient tenance and supervision ensure that written procedures access and working space shall be provided and maintained have been adopted to prohibit equipment on both sides of about all electrical equipment to permit ready and safe op- the aisle from being open at the same time and qualified eration and maintenance of such equipment. persons who are authorized will service the installation. (A) Working Space.Working space for equipment operat- (2) Width of Working Space. The width of the working ing at 600 volts, nominal, or less to ground and likely to space in front of the electrical equipment shall be the width require examination, adjustment, servicing, or maintenance of the equipment or 762 mm (30 in.), whichever is greater. 70-36 NATIONAL ELECTRICAL CODE 2009 Edition ARTICLE 110—REQUIREMENTS FOR ELECTRICAL INSTALLATIONS 110.26 In all cases,the work space shall permit at least a 90 degree panelboards, or motor control centers installed indoors.Ad- opening of equipment doors or hinged panels. ditional lighting outlets shall not be required where the work space is illuminated by an adjacent light source or as (3) Height of Working Space. The work space shall be permitted by 2f0.70(A)(1), Exception No. I, for switched clear and extend from the grade, floor, or platform to the height required by 110.26(E). Within the height require- receptacles. In electrical equipment rooms, the illumination menns of this section, other equipment that is associated shall not be controlled by automatic means only. with the electrical installation and is located above or be- (E) Headroom.The minimum headroom of working spaces low the electrical equipment shall be permitted to extend about service equipment, switchboards, panelboards, or motor not more than 150 mm (6 in.) beyond the front of the control centers shall be 2.0 m (6th ft). Where the electrical electrical equipment. equipment exceeds 2.0 m (6ti2 ft) in height, the minimum (B) Clear Spaces. Working space required by this section headroom shall not be less than the height of the equipment. shall not be used for storage. When normally enclosed live Exception: In existing dwelling units, service equipment parts are exposed for inspection or servicing, the working or panelboards that do not exceed 200 amperes shall be space, if in a passageway or general open space, shall be permitted in spaces where the headroom is less than 2.0 m suitably guarded. (6112 ft). (C) Entrance to and Egress from Working Space. (F) Dedicated Equipment Space. All switchboards, pan- (1) Minimum Required, At least one entrance of su elboards, distribution boards, and motor control centers lfi- cient area shall be provided to give access to and egress shall be located in dedicated spaces and protected from from working space about electrical equipment. damage. (2) Large Equipment. For equipment rated 1200 amperes Exception: Control equipment that by its very nature or or more and over 1.8 m (6 ft) wide that contains overcur- because of other rules of the Code must be adjacent to or rent devices, switching devices, or control devices, there within sight of its operating machinery shall be permitted shall be one entrance to and egress from the required work- in those locations. ing space not less than 610 mm (24 in.) wide and 2.0 m (1) Indoor. Indoor installations shall comply with (61/2 ft) high at each end of the working space. 110.26(F)(1)(a) through (17)(1)(d). A single entrance to and egress front the required work- ing space shall be permitted where either of the conditions (a) Dedicated Electrical Space. The space equal to the in 110.26(C)(2)(a) or (C)(2)(b) is met. width and depth of the equipment and extending from the floor to a height of 1.8 m (6 ft) above the equipment or to (a) Unobstructed Egress. Where the location permits a the structural ceiling, whichever is lower,shall be dedicated continuous and unobstructed way of egress travel, a single to the electrical installation. No piping, ducts, leak protec- entrance to the working space shall be permitted. lion apparatus, or other equipment foreign to the electrical (b) Extra Working Space. Where the depth of the installation shall be located in this zone. working space is twice that required by 110.26(A)(1), a Exception: Suspended ceilings with removable panels shall single entrance shall be permitted. It shall be located such that the distance from the equipment to the nearest edge of be permitted within the 1.8-m {6 ft) zone. the entrance is not less than the minimum clear distance (b) Foreign Systems. The area above the dedicated specified in Table 110.26(A)(1) for equipment operating at space required by 110.26(F)(1)(a)shall be permitted to con- that voltage and in that condition. tain foreign systems, provided protection is installed to avoid damage to the electrical equipment from condensa- (3) Personnel Doors. Where equipment rated IZOQ A 01C lion, leaks, or breaks in such foreign systems. more that contains overcurtent devices, switching devices, or control devices is installed and there is a personnel (c) Sprinkler Protection. Sprinkler protection shall be door(S) intended for entrance to and egress from the work- permitted for the dedicated space where the piping com- ing space less than 7.6 m (25 ft) from the nearest edge of plies with this section, the working Space,the door(s)shall open in Lhe direction of (d) Suspended Ceilings. A dropped, suspended, or egress and be equipped with panic bars, pressure plates, or similar ceiling that does not add strength to the building other devices that are normally latched but open under structure shall not be considered a structural ceiling. simple,pressure. (2) Outdoor. Outdoor electrical equipment shall be installed (D) Illumination. Illumination shall be provided for all in suitable enclosures and shall be protected from accidental working spaces about service equipment, switchboards, contact by unauthorized personnel, or by vehicular traffic, or 2008 Edition NATIONAL ELECTRICAL CODE 70-37 110.27 ARTICLE 110--REQUIREMENTS FOR ELEC'T'RICAL INSTALLA"T"IONS by accidental spillage or leakage from piping systems. The surrounded by a wall, screen, or fence, access to which is working clearance space shall include the zone described in controlled by a lock(s) or other approved means, shall be 110.26(A). No architectural appurtenance or other equipment considered to be accessible to qualified persons only. shall be located in this zone. The type of enclosure used in a given case shall be designed and constructed according to the nature and (G) Locked Electrical Equipment Rooms or Enelo- degree of the hazard(s) associated with the installation. sures. Electrical equipment rooms or enclosures housing For installations other than equipment as described in electrical apparatus that are controlled by a lock(S)shall be 110.31(D), a wall, screen, or fence shall be used to enclose considered accessible to qualified persons. an outdoor electrical installation to deter access by persons who are not qualified.A fence shall not be less than 2.1 m 110.27 Guarding of Live Parts. (7 ft) in height or a combination of 1.8 m (6 ft) or more of (A) Live Parts Guarded Against Accidental. Contact. fence fabric and a 300-mm (1-ft) or more extension utiliz- Except as elsewhere required or permitted by this Cade, ing three or more strands of barbed wire or equivalent.The live parts of electrical equipment operating at 50 volts or distance from the fence to live parts shall be not less than more shall be guarded against accidental contact by ap- given in Table 110.31. proved enclosures or by any of the following means: (1) By location in a room,vault,or similar enclosure that is Table 110.31 Minimum Distance from Fence to Live farts accessible only to qualified persons. (2) By suitable permanent, substantial partitions or screens Minimum Distance to Live Parts arranged so that only qualified persons have access to the space within reach of the live parts. Any openings Nominal Voltage m ft in such partitions or screens shall be sized and located 601 — 13,799 3.05 10 so that persons are not likely to come into accidental 13,800— 230,000 4.57 15 contact with the live parts or to bring conducting ob- Over 230,000 5.49 18 jects into contact with them. Note: For clearances of conductors for specific system voltages and (3) By location on a suitable balcony, gallery, or platform typical BIL ratings, see ANSI C2-2007, National Electrical Safety elevated and arranged so as to exclude unqualified per- Code. sons. (4) By elevation of 2.5 m (8 ft) or more above the floor or FPN: See Article 450 for construction requirements for other working surface. transformer vaults. (B) Prevent Physical Damage. In locations where electri- (A) Fire Resistance of Electrical Vaults. The walls, roof, cal equipment is likely to be exposed to physical damage, floors, and doorways of vaults containing conductors and enclosures or guards shall be so arranged and of such equipment over 600 volts, nominal, shall be constructed of strength as to prevent such damage, materials that have adequate structural strength for the con- (C) Warning Signs.Entrances to rooms and other guarded ditions, with a minimum fire rating of 3 hours.The floors of locations that contain exposed live parts shall be marked vaults in contact with the earth shall be of concrete that is with conspicuous warning signs forbidding unqualified per- not less than 102 mm (4 in.) thick, but where the vault is sons to enter. constructed with a vacant space or other stories below it, the floor shall have adequate structural strength for the load FPN: For motors, see 430.232 and 430.233. For over 600 imposed on it and a minimum fire resistance of 3 hours. For volts, see 110.34. the purpose of this section, studs and wallboards shall not be considered acceptable. III. Over 600 Volts, Nominal (B) Indoor Installations. 110.30 General. Conductors and equipment used on cir- cuits over 600 volts, nominal, shall comply with Part I of (1) In Places Accessible to Unqualified Persons. Indoor this article and with 110.30 through 110.40, which supple- electrical installations that are accessible to unqualified per- ment or modify Part I. In no case shall the provisions of sons shall be made with metal-enclosed equipment. Metal- this part apply to equipment on the supply side of the ser- enclosed switchgear, unit substations, transformers, pull vice point. boxes, connection boxes, and other similar associated equip- ment shall be marked with appropriate caution signs. Open- 110.31 Enclosure for Electrical Installations. Electrical ings in ventilated dry-type transformers or similar openings installations in a vault, room, or closet or in an area in other equipment shall be designed so that foreign objects 70-38 NATIONAL ELECTRICAL.CODE 2009 Edition ARTICLE 110—REQUIREMENTS FOR ELECTRICAL INSTALLATIONS 110.34 inserted through these openings are deflected from energized provided to give access to the working space about electri- parts. cal equipment. (2) In Places Accessible to Qualified Persons Only. In- (1) Large Equipment. On switchboard and control panels door electrical installations considered accessible only to exceeding 1.8 m (6 ft) in width, there shall be one entrance qualified persons in accordance with this section shall com- at each end of the equipment. A single entrance to the ply with 110.34, 110.36, and 490.24. required working space shall be permitted where either of the conditions in 110.33(A)(1)(a) or (A)(I)(b) is met. (C) Outdoor Installations. (a) Unobstructed Exit. Where the Iocation permits a continuous and unobstructed way of exit travel, a single (1) In Places Accessible to Unqualified Persons. Outdoor entrance to the working space shall be permitted. electrical installations that are open to unqualified persons (b) Extra Working Space. Where the depth of the work- shall comply with Parts 1, II, and III of Article 225. ing space is twice that required by 110.34(A), a single en- • trance shall be permitted. It shall be located so that the (2) In Places Accessible to Qualified Persons Only. Out- distance from the equipment to the nearest edge of the door electrical installations that have exposed live parts entrance is not less than the minimum clear distance speci- shall be accessible to qualified persons only in accordance fied in Table 110.34(A) for equipment operating at that with the first paragraph of this section and shall comply voltage and in that condition. with 1 10.34, 110.36, and 490.24. (2) Guarding. Where bare energized parts at any voltage (D) Enclosed Equipment Accessible to Unqualified Per- or insulated energized parts above 600 volts, nominal, to sons. Ventilating or similar openings in equipment shall be ground are located adjacent to such entrance, they shall be designed such that foreign objects inserted through these suitably guarded. openings are deflected from energized parts. Where ex- (3) Personnel Doors. Where there is a ,personnel door(s) posed to physical damage from vehicular traffic, suitable intended for entrance to and egress from the working space guards shall be provided. Nonmetallic or metal-enclosed less than 7.6 m(25 ft)from the nearest edge of the working equipment located outdoors and accessible to the general space, the door(s) shall open in the direction of egress public shall be designed such that exposed nuts or bolts and be equipped with panic bars, pressure plates, or cannot be readily removed, permitting access to live parts. other device$ that are normally Patched but open under Where nonmetallic or metal-enclosed equipment is acces- simple pressure, sible to the general public and the bottom of the enclosure is less than 2.5 m (8 ft) above the floor or grade level, (B) Access. Permanent ladders or stairways shall be pro- the enclosure door or hinged cover shall be kept locked vided to give safe access to the working space around Doors and covers of enclosures used solely as pull electrical equipment installed on platforms, balconies, or boxes, splice boxes, or junction boxes shalt be locked, mezzanine floors or in attic or roof rooms or spaces. bolted, or screwed on. Underground box covers that weigh over 45.4 kg (100 lb) shall be considered as meet- 110.34 Work Space and Guarding. ing this requirement. (A) Working Space. Except as elsewhere required or 110.32 Work Space About Equipment. Sufficient space permitted in this Code, equipment likely to require ex- aminatinn, adjustment, servicing, or maintenance while shall be provided and maintained about electrical equipment energized sha�lf have clear working space in the direction to permit ready and safe operation and maintenance of such of access to live parts of the electrical equipment and equipment. Where energized parts are exposed, the minimum shall be not less than specified in Table I 10.34(A). Dis- tances work space shall be not less than 2.0 m (6'/a ft) high faeces shall be measured from the live parts, if such are (measured vertically from the floor or platform) or not less exposed, or From the enclosure front or opening if such than 914 mm(3 ft)wide(measured parallel to the equipment). are enclosed, The depth shall be as required in 110.34(A). In all cases, the work space shall permit at least a 90 degree opening of doors Exception: Working space shall not be required in back of or hinged panels. equipment such as dead front switchboards or control as- semblies where there are no renewable or adjustable parts 110.33 Entrance to Enclosures and Access to Working (such as fuses or switches) on the back and where all con- Space. nections are accessible from locations other than the back. Where rear access is required to work on de-energized (A) Entrance.At least one entrance to enclosures for elec- parts on the back of enclosed equipment, a minimum trical installations as described in 110.31 not less than working space of 762 mm (30 in.) horizontally shall be 610 mm (24 in.) wide and 2.0 m (61/2 ft) high shall be provided. 2008 Edition NATIONAL ELECTRICAL CODE 70.39 110.36 ARTICLE 110--REQUIREMENTS FOR ELECTRICAL INSTALLA'T'IONS Table 110,34(A) Minimum Depth of Clear Working Space at Table 110.34(E) Elevation of Unguarded Live Parts Above Electrical Equipment Working Space Nominal Minimum Clear Distance Elevation Voltage Nominal Voltage to Ground Condition 1 Condition 2 Condition 3 Between Phases m ft 601-2500 V 900 mm (3 ft) 1,2 m (4 ft) 1.5 m (5 ft) 601-7500 V 2.8 9 2501-9000 V 1.2 m (4 ft) 1.5 m (5 ft) 1.8 m (6 ft) 7501-35,000 V 2.9 9 ft 6 in. 9001-25,000 V 1.5 m (5 ft) 1.8 m (6 ft) 2.8 m (9 ft) Over 35 kV 2.9 m +9.5 mm1kV 9 ft 6 in. + 25,001 V-75 kV 1.8 m (6 ft) 2.5 m (8 ft) 3.0 m (10 ft) above 35 0.37 in./kV Above 75 kV 2.5 m (8 ft) 3.0 m (10 ft) 3.7 m (12 ft) above 35 Note: Where the conditions are as follows: Condition 1 —Exposed live parts on one side of the working space {E) Elevation Of Unguarded Live Parts. Unguarded live and no live or grounded parts on the other side of the working space, parts above working space shall be maintained at elevations or exposed live parts on both sides of the working space that are not less than required by Table 110.34(E), effectively guarded by insulating materials. Condition 2—Exposed live parts on one side of the working space (F) Protection of Service Equipment, Metal-Enclosed and grounded parts on the other side of the working space.Concrete, Power Switchgear, and Industrial Control Assemblies. brick, or tile walls shall be considered as grounded. Condition 3—Exposed five parts on both sides of the working space. Pipes or ducts foreign to the electrical installation and re- quiring periodic maintenance or whose malfunction would endanger the operation of the electrical system shall not be (B) Separation from Low-Voltage Equipment. Where located in the vicinity of the service equipment, metal- switches, cutouts, or other equipment operating at 600 enclosed power switchgear, or industrial control assemblies. volts, nominal, or less are installed in a vault, room, or Protection shall be provided where necessary to avoid damage enclosure where there are exposed live parts or exposed from condensation leaks and breaks in such foreign systems. wiring operating at over 600 volts, nominal, the high- Piping and other facilities shall not be considered foreign if voltage equipment shall be effectively separated from the provided for fire protection of the electrical installation. space occupied by the low-voltage equipment by a suitable partition, fence, or screen. 110.36 Circuit Conductors.Circuit conductors shall be per- mitted to be installed in raceways;in cable trays;as metal-clad Exception: Switches or other equipment operating at 600 cable,as bare wire,cable, and busbars; or as Type MV cables volts, nominal, or less and serving only equipment within or conductor as provided in 300.37, 300.39, 300.40, and the high-voltage vault, room, or enclosure shall be permit- 300,50. Bare live conductors shall comply with 490.24. ted to be installed in the high-voltage vault, room, or en- Insulators, together with their mounting and conductor at- closure without a partition,fence, or screen if accessible to tachments, where used as supports for wires,single-conductor qualified persons onlY cables, or busbars, shall be capable of safely withstanding the maximum magnetic forces that would prevail if two or more (C) Locked Rooms or Enclosures. The entrance to all conductors of a circuit were subjected to short-circuit current. buildings, vaults, rooms, or enclosures containing exposed Exposed runs of insulated wires and cables that have a live parts or exposed conductors operating at over 600 bare lead sheath or a braided outer covering shall be sup- volts, nominal, shall be kept locked unless such entrances ported in a manner designed to prevent physical damage to are under the observation of a qualified person at all times. the braid or sheath. Supports for lead-covered cables shall Where the voltage exceeds 600 volts, nominal, perma- be designed to prevent electrolysis of the sheath. nent and conspicuous warning signs shall be provided, reading as follows: 110.40 Temperature Limitations at Terminations. Con- ductors shall be permitted to be terminated based on the DANGER — HIGH VOLTAGE— KEEP OUT 90°C (194°F) temperature rating and ampacity as given (D) Illumination. Illumination shall be provided for all in Table 310.67 through Table 310.86, unless otherwise working spaces about electrical equipment. The lighting identified. outlets shall be arranged so that persons changing lamps or IV. Tunnel Installations over 600 Volts, Nominal making repairs on the lighting system are not endangered by live parts or other equipment. 110.51 General. The points of control shall be located so that persons (A) Covered.The provisions of this part shall apply to the are not likely to come in contact with any live part or installation and use of high-voltage power distribution and moving part of the equipment while turning on the lights. utilization equipment that is portable, mobile, or both, such 70-40 NATIONAL ELECTRICAL CODE 2009 Edition ARTICLE 110—REQUIREMENTS FOR ELECTRICAL INSTALLATIONS 110.72 as substations, trailers, cars, mobile shovels, draglines, The switch or circuit breaker for a transformer shall have hoists, drills, dredges, compressors, pumps, conveyors, un- an ampere rating not less than the ampacity of the trans- derground excavators, and the like. former supply conductors. The switch or circuit breaker for (B) Other Articles. The requirements of this part shall be a motor shall comply with the applicable requirements of Article 430. additional to,or amendatory of, those prescribed in Articles 100 through 490 of this Code. 110.59 Enclosures. Enclosures for use in tunnels shall be (C) Protection Against Physical Damage. Conductors dripproof, weatherproof, or submersible as required by the and cables in tunnels shall be located above the tunnel floor environmental conditions. Switch or contactor enclosures and so placed or guarded to protect them from physical shall not be used as junction boxes or as raceways for damage. conductors feeding through or tapping off to other switches, unless the enclosures comply with 312.8. 110.52 Overcurrent Protection. Motor-operated equip- ment shall be protected from overcurrent in accordance V. Manholes and Other Electrical Enclosures Intended with Parts III, IV, and V of Article 430. Transformers shall for Personnel Entry, All Voltages be protected from overcurrent in accordance with 450.3. 110.53 Conductors. High-voltage conductors in tunnels 110.70 General.Electrical enclosures intended for person- nel entry and specifically fabricated for this purpose shall shall be installed in metal conduit or other metal raceway, be of sufficient size to provide safe work space about elec- trical equipment with live parts that is likely to require Multiconductor portable cable shall be permitted to supply examination, adjustment, servicing, or maintenance while mobile equipment. energized. Such enclosures shall have sufficient size to per- 110.54 Bonding and Equipment Grounding Conduc- mit ready installation or withdrawal of the conductors em- ployed without damage to the conductors or to their insu- lation, They shall comply with the provisions of this part. (A) Grounded and Bonded. All non–current-carrying metal parts of electrical equipment and all metal raceways Exception: Where electrical enclosures covered by Fart V and cable sheaths shall be Solidly grounded and bonded to of this article are part of an industrial wiring system oper- all metal pipes and rails at the portal and at intervals not ating under conditions of maintenance and supervision that exceeding 300 m (1000 ft) throughout the tunnel. ensure that only qualified persons monitor and supervise the system, they shall be permitted to be designed and in- (B) Equipment Grounding Conductors. An equipment stalled in accordance with appropriate engineering prac- grounding conductor shall be run with circuit conductors tice. If required by the authority having jurisdiction, design inside the metal raceway or inside the multiconductor cable documentation shall be provided. jacket. The equipment grounding conductor shall be per- mitted to be insulated or bare. 110.71 Strength. Manholes, vaults, and their means of ac- cess shall be designed under qualified engineering supervi- 110.55 'I�ansformers, Switches, and Electrical Equip- sion and shall withstand all loads likely to be imposed on ment. All transformers, switches, motor controllers, mo- the structures. tors, rectifiers, and other equipment installed belowground shall be protected from physical damage by location or FPN: See ANSI C2-2007,National Electrical Safety Code, guarding. for additional information on the loading that can be ex- pected to bear on underground enclosures. 110.56 Energized Parts. Bare terminals of transformers, switches, motor controllers, and other equipment shall be 110.72 Cabling Work Space. A clear work space not less enclosed to prevent accidental contact with energized parts. than 900 mm(3 ft)wide shall be provided where cables are located on both sides, and not less than 750 mm (21/2 ft) 110.57 Ventilation System Controls. Electrical controls where cables are only on one side. The vertical headroom for the ventilation system shall be arranged so that the shall be not less than 1.8 m (6 ft) unless the opening is airflow can be reversed. within 300 mm (I ft), measured horizontally, of the adja- cent interior side wall of the enclosure. 110.58 Disconnecting Means. A switch or circuit breaker that simultaneously opens all ungrounded conductors of the Exception: A manhole containing only one or more of the circuit shall be installed within sight of each transformer or following shall be permitted to have one of the horizontal motor location for disconnecting the transformer or motor. work space dimensions reduced to 600 mm (2 ft) where the 2008 Edition NATIONAL ELECTRICAL CODE 70-41 110.73 ARTICLE I 10—REQUIREMENTS FOR ELECTRICAL INSTALLATIONS other horizontal clear work space is increased so the sum (3) Class 2 or Class 3 remote-control and signaling cir- of the two dimensions is not less than 1.8 m (6 ft): cults, or both, supplied in accordance with 725.121 (1) Optical fiber cables as covered in Article 770 (B) Obstructions. Manhole openings shall be free of pro- (2) Power-limited fire alarm circuits supplied in accor- trusions that could injure personnel or prevent ready egress. dance with 760.121 (3) Class 2 or Class 3 remote-control and signaling cir- (C) Location. Manhole openings for personnel shall be cults, or both, supplied in accordance with 725.121 located where they are not directly above electrical equip- ment or conductors in the enclosure.Where this is not prac- 110.73 Equipment Work Space. Where electrical equip- ticable, either a protective barrier or a fixed ladder shall be ment with live parts that is likely to require examination, ad- provided. justment, servicing, or maintenance while energized is in- (D) Covers. Covers shall be over 45 kg (100 lb) or other- stalled in a manhole, vault, or other enclosure designed for wise designed to require the use of tools to open.They shall personnel access, the work space and associated requirements be designed or restrained so they cannot fall into the man- in 110.26 shall be met for installations operating at 600 volts hole or protrude sufficiently to contact electrical conductors or less. Where the installation is over 600 volts, the work or equipment within the manhole. space and associated requirements in 110.34 shall be met. A manhole access cover that weighs over 45 kg(100 lb)shall be (E) Marking. Manhole covers shall have an identifying considered as meeting the requirements of 110.34(C). mark or logo that prominently indicates their function, such as "electric," 110.74 Bending Space for Conductors. Bending space for conductors operating at 600 volts or below shall be 110.76 Access to Vaults and Tunnels. provided in accordance with the requirements of 314.28. (A) Location. Access openings for personnel shall be lo- Conductors operating at over 600 volts shall be provided cated where they are not directly above electrical equip- with bending space in accordance with 314.71(A) and ment or conductors in the enclosure. Other openings shall 314.71(B), as applicable. All conductors shall be cabled, be permitted over equipment to facilitate installation,main- racked up, or arranged in an approved manner that provides tenance, or replacement of equipment. ready and safe access for persons to enter for installation and maintenance. (B) Locks.In addition to compliance with the requirements of 110.34,if applicable, access openings for personnel shall Exception: Where 314.71(B) applies, each row or column be arranged such that a person on the inside can exit when of ducts on one wall of the enclosure shall be calculated the access door is locked from the outside, or in the case of individually, and the single row or column that provides the normally locking by padlock, the locking arrangement shall maximum distance shall be used be such that the padlock can be closed on the locking sys- 110.75 Access to Manholes. tem to prevent locking from the outside. (A) Dimensions. Rectangular access openings shall not be 110.77 Ventilation. Where manholes, tunnels, and vaults less than 650 mm x 550 mm(26 in. x 22 in.). Round access have communicating openings into enclosed areas used by openings in a manhole shall be not less than 650 mm the public, ventilation to open air shall be provided wher- (26 in.) in diameter. ever practicable. Exception: A manhole that has a fixed ladder that does not 110.78 Guarding. Where conductors or equipment, or obstruct the opening or that contains only one or more of both, could be contacted by objects falling or being pushed the following shall be permitted to reduce the minimum through a ventilating grating,both conductors and live parts cover diameter to 600 min (2 ft): shall be protected in accordance with the requirements of (I) Optical fiber cables as covered in Article 770 110.27(A)(2) or 110.31(8)(1), depending on the voltage. (2) Power-limited fire alarm circuits supplied in accor- 110.79 Fixed Ladders. Fixed ladders shall be corrosion dance with 760.121 resistant. 70-42 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 200 USE AND IDENTIFICATION OF GROUNDED CONDUCTORS 200.6 Chapter 2 Wiring and Protection tinuous white or gray outer finish or by three continuous ARTICLE 200 white stripes on other than green insulation along its entire Use and Identification length. Wires that have their outer covering finished to of Grounded Conductors show a white or gray color but have colored tracer threads in the braid identifying the source of manufacture shall be considered as meeting the provisions of this section. Insu- 200.1 Scope. This article provides requirements for the lated grounded conductors shall also be permitted to be following: identified as follows: (1) identification of terminals (1) The grounded conductor of a mineral-insulated, metal- (2) Grounded conductors in premises wiring systems sheathed cable shall be identified at the time of instal- (3) Identification of grounded conductors lation by distinctive marking at its terminations. FPN: See Article 100 for definitions of Grounded Conduc- (2) A single-conductor, sunlight-resistant, outdoor-rated for and Grounding Conductor. cable used as a grounded conductor in photovoltaic power systems as permitted by 690.31 shall be identi- 200.2 General. All premises wiring systems, other than fied at the time of installation by distinctive white circuits and systems exempted or prohibited by 210.10, marking at all terminations. 215.7, 250.21, 250.22, 250.162, 503.155, 517.63, 668.11, (3) Fixture wire shall comply with the requirements for 668.21, and 690.41, Exception, shall have a grounded con- grounded conductor identification as specified in 402.8. ductor that is identified in accordance with 200.6. The (4) For aerial cable, the identification shall be as above, or grounded conductor shall comply with 200.2(A) and (B). by means of a ridge located on the exterior of the cable (A) Insulation. The grounded conductor, where insulated, so as to identify it, shall have insulation that is (1) suitable, other than color, (B) Sizes Larger Than 6 AWG. An insulated grounded for any ungrounded conductor of the same circuit on cir- conductor larger than 6 AWG shall be identified by one of cuits of less than 1000 volts or impedance grounded neutral the following means: systems of 1 kV and over, or (2) rated not less than 600 (1) By a continuous white or gray outer finish. volts for solidly grounded neutral systems of 1 kV and over as described in 250.184(A). (2) By three continuous white stripes along its entire length on other than green insulation. (B) Continuity. The continuity of a grounded conductor (3) At the time of installation, by a distinctive white or shall not depend. on a connection to a metallic enclosure, gray marking at its terminations. This marking shall raceway, or cable armor. encircle the conductor or insulation. 200.3 Connection to Grounded System. Premises wiring (C) Flexible Cords. An insulated conductor that is in- shall not be electrically connected to a supply system un- tended for use as a grounded conductor, where contained less the latter contains, for any grounded conductor of the within a flexible cord, shall be identified by a white or gray interior system, a corresponding conductor that is outer finish or by methods permitted by 400.22. grounded. For the purpose of this section, electrically con- (D) Grounded Conductors of Different Systems. Where nected shall mean connected so as to be capable of carrying grounded conductors of different systems are installed in current, as distinguished from connection through electro- the same raceway,cable,box, auxiliary gutter,or other type magnetic induction. of enclosure, each grounded conductor shall be identified Exception: Listed utility-interactive inverters identified for by system. Identification that distinguishes each system use in distributed resource generation systems such as pho- grounded conductor shall be permitted by one of the fol- tovoltaic and fuel cell power systems shall be permitted to lowing means: be connected to premises wiring without a grounded Con- (1) One system grounded conductor shall have an outer ductor where the connected premises wiring or utility sys- covering conforming to 200.6(A) or (B). tem includes a grounded conductor. (2) The grounded conductor(s) of other systems shall have a different outer covering conforming to 200.6(A) or 200.6 Means of Identifying Grounded Conductors. 200.6(B) or by an outer covering of white or gray with (A) Sizes 6 AWG or Smaller. An insulated grounded con- a readily distinguishable colored stripe other than green ductor of 6 AWG or smaller shall be identified by a con- running along the insulation. 2008 Edition NATIONAL ELECTRICAL CODE 70-3 200.7 ARTICLE 200--USE AND IDENTIFICATION OF GROUNDED CONDUCTORS (3) Other and different means of identification as allowed conductor is visible and accessible. Identification shall by 200.6(A) or (B) that will distinguish each system encircle the insulation and shall be a color other than grounded conductor. white, gray, or green. This means of identification shall be permanently posted at (2) Where a cable assembly contains an insulated conduc- each branch-circuit panelboard. for for single-pole, 3-way or 4-way switch loops and the conductor with white or gray insulation or a mark- (E) Grounded Conductors of Multiconductor Cables. ing of three continuous white stripes is used for the The insulated grounded conductors in a multiconductor supply to the switch but not as a return conductor from cable shall be identified by a continuous white or gray outer the switch to the switched outlet. In these applications, finish or by three continuous white stripes on other than the conductor with white or gray insulation or with green insulation along its entire length. Multiconductor flat three continuous white stripes shall be permanently re- cable 4 AWG or larger shall be permitted to employ an identified to indicate its use by painting or other effec- external ridge on the grounded conductor. tive means at its terminations and at each location Exception No. 1: Where the conditions of maintenance where the conductor is visible and accessible. and supervision ensure that only qualified persons service (3) Where a flexible cord, having one conductor identified the installation, grounded conductors in multiconductor by a white or gray outer finish or three continuous cables shall be permitted to be permanently identified at white stripes or by any other means permitted by their terminations at the time of installation by a distinctive 400.22, is used for connecting an appliance or equip- white marking or other equally effective means. ment permitted by 400.7. This shall apply to flexible cords connected to outlets whether or not the outlet is Exceptive: No. 2: The grounded conductor qf'a multicon- supplied by a circuit that has a grounded conductor. ductor varnished-cloth-insulated cable shall be permitted to be identified at its terminations at the time of installation FPN: The color gray may have been used in the past as an by a distinctive white marking or other equally effective ungrounded conductor. Care should be taken when working means. on existing systems. FPN: The color gray may have been used in the past as an 200.9 Means of Identification of Terminals. The identifi- ungrounded conductor.Care should be taken when working cation of terminals to which a grounded conductor is to be on existing systems. connected shall be substantially white in color. The identi- 200.7 Use of Insulation of a White or Gray Color or fication of other terminals shall be of a readily distinguish- with Three Continuous White Stripes. able different color. (A) General. The following shall be used only for the Exception: Where the conditions of maintenance and su- grounded circuit conductor, unless otherwise permitted in pervision ensure that only qualified persons service the in- 200.7(B) and (C): stallations, terminals for grounded conductors shall be per- (1) A conductor with continuous white or gray covering mitted to be permanently identified at the time of (2) A conductor with three continuous white stripes an installation by a distinctive white marking or other equally other than green insulation effective means. (3) A marking of white or gray color at the termination 200.10 Identification of Terminals. (B) Circuits of Less Than 50 Volts. A conductor with (A) Device Terminals. All devices, excluding panel- white or gray color insulation or three continuous white boards, provided with terminals for the attachment of con- stripes or having a marking of white or gray at the termi- ductors and intended for connection to more than one side nation for circuits of less than 50 volts shall be required to of the circuit shall have terminals properly marked for iden- be grounded only as required by 250.20(A). tification, unless the electrical connection of the terminal (C) Circuits of 50 Volts or More. The use of insulation intended to be connected to the grounded conductor is that is white or gray or that has three continuous white clearly evident, stripes for other than a grounded conductor for circuits Exception: Terminal identification shall not be required for of 50 volts or more shall be permitted only as in (1) devices that have a normal current rating of over 30 am- through (3). peres, other than polarized attachment plugs and polarized (I) If part of a cable assembly and where the insulation is receptacles for attachment plugs as required in 200.10(B). permanently reidentified to indicate its use as an un- grounded conductor, by painting or other effective (B) Receptacles, Plugs, and Connectors. Receptacles, means at its termination, and at each location where the polarized attachment plugs, and cord connectors for plugs 70114 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 210—BRANCH CIRCUITS 210.4 and polarized plugs shall have the terminal intended for listed in Table 210.2 amend or supplement the provisions in connection to the grounded conductor identified as follows: this article and shall apply to branch circuits referred to (1) Identification shall be by a metal or metal coating that therein. is substantially white in color or by the word white or the letter W located adjacent to the identified terminal. 210.3 Rating. Branch circuits recognized by this article (2) If the terminal is not visible, the conductor entrance shall be rated in accordance with the maximum permitted hole for the connection shall be colored white or ampere rating or setting of the overcurrent device.The rat- marked with the word white or the letter W. ing for other than individual branch circuits shall be 15, 20, 30, 40, and 50 amperes. Where conductors of higher am- FPN: See 250.126 for identification of wiring device pacity are used for any reason, the ampere rating or setting equipment grounding conductor terminals. of the specified overcurrent device shall determine the cir- (C) Screw Shells. For devices with screw shells, the ter- cuit rating. minal for the grounded conductor shall be the one con- Exception: Multioutlet branch circuits greater than 50 am- nected to the screw shell. peres shall be permitted to supply nonlighting outlet loads (D) Screw Shell Devices with Leads. For screw shell de- on industrial premises where conditions of maintenance vices with attached leads, the conductor attached to the and supervision ensure that only qualified persons service screw shell shall have a white or gray finish. The outer the equipment. finish of the other conductor shall be of a solid color that will not be confused with the white or gray finish used to 210.4 Multiwire Branch Circuits. identify the grounded conductor. (A) General. Branch circuits recognized by this article FPN: The color gray may have been used in the past as an shall be permitted as multiwire circuits.A multiwire circuit ungrounded conductor.Care should be taken when working shall be permitted to be considered as multiple circuits.All on existing systems. conductors of a multiwire branch circuit shall originate (E) Appliances. Appliances that have a single-pole switch from the same panelboard or similar distribution equip- or a single-pole overcurrent device in the line or any line- ment, connected screw shell lampholders, and that are to be con- FPN: A 3-phase, 4-wire, wye-connected power system nected by (1) a permanent wiring method or (2) field- used to supply power to nonlinear loads may necessitate installed attachment plugs and cords with three or more that the power system design allow for the possibility of wires (including the equipment grounding conductor), shall high harmonic currents on the neutral conductor. have means to identify the terminal for the grounded circuit (B) Disconnecting Means. Each multiwire branch circuit conductor (if any). Shall be provided with a means that will simultaneously 200.11 Polarity of Connections. No grounded conductor disconnect all ungrounded conductors at the point where shall be attached to any terminal or lead so as to reverse the the branch circuit originates. designated polarity. (C) Line-to-Neutral Loads. Multiwire branch circuits shall supply only line-to-neutral loads. Exception No. 1: A multiwire branch circuit that supplies ARTICLE 214 only one utilization equipment. Branch Circuits Exception No. 2: Where all ungrounded conductors of the multiwire branch circuit are opened simultaneously by the branch-circuit overcurrent device. 1. General Provisions FPN: See 300.13(B) for continuity of grounded conductor 210.1 Scope. This article covers branch circuits except for on multiwire circuits. branch circuits that supply only motor loads, which are (D) Grouping. The ungrounded and grounded conductors covered in Article 430. Provisions of this article and Article of each multiwire branch circuit shall be grouped by wire 430 apply to branch circuits with combination loads. ties or similar means in at least one Iocation within the 210.2 Other Articles for Specific-Purpose Branch Cir- panelboard or other point of origination. cuits.Branch circuits shall comply with this article and also Exception: The requirement for grouping shall not apply if with the applicable provisions of other articles of this Code. the circuit enters from. a cable or raceway unique to the The provisions for branch circuits supplying equipment circuit that makes the grouping Obvious. 2008 Edition NATIONAL ELECTRICAL CODE 70-45 210.5 ARTICLE 210--BRANCH CIRCUITS Table 210.2 Specific-Purpose Branch Circuits 210.5 Identification for Branch Circuits. Equipment Article Section (A) Grounded Conductor. The grounded conductor of a branch circuit shall be identified in accordance with 200.6. Air-conditioning and 440.6, 440.31, refrigerating equipment 440.32 (B) Equipment Grounding Conductor. The equipment Audio signal processing, 640.8 grounding conductor shall be identified in accordance with amplification, and 250.119. reproduction equipment Busways 368.17 (C) Ungrounded Conductors.Where the premises wiring Circuits and equipment 720 system has branch circuits supplied from more than one operating at less than nominal voltage system, each ungrounded conductor of a 50 volts Central heating equipment 422.12 branch circuit shall be identified by phase or line and sys- other than fixed electric tem at all termination, connection, and splice points. The space-heating equipment means of identification shall be permitted to be by separate Class 1, Class 2, and Class 3 725 color coding, marking tape, tagging, or other approved remote-control, signaling, means. The method utittized for conductors originating and power-limited circuits within each branch-circuit panelboard or similar branch- Cranes and hoists 610.42 circuit distribution equipment shall be documented in a Electric signs and outline 600.6 manner that is readily available: or shall he permanently lighting posted at each branch-circuit panelboard or similar branch- Electric welders 630 circuit distribution equipment. Electrified truck,parking space 626 Elevators, dumbwaiters, 620.61 escalators, moving walks, 210.6 Branch-Circuit Voltage Limitations. The nominal wheelchair lifts, and stairway voltage of branch circuits shall not exceed the values per- chair lifts mitted by 210.6(A) through (E). Fire alarm systems 760 Fixed electric heating 427.4 (A) Occupancy Limitation. In dwelling units and guest equipment for pipelines and rooms or guest suites of hotels, motels, and similar oc- vessels cupancies, the voltage shall not exceed 120 volts, nomi- Fixed electric space-heating 424.3 nal, between conductors that supply the terminals of the equipment following: Fixed outdoor electrical 426.4 deicing and snow-melting (1) Luminaires equipment (2) Cord-and-plug-connected loads 1440 volt-amperes, Information technology 645.5 nominal, or less or less than 114 hp equipment Infrared lamp industrial 422.48, 424.3 (B) 120 Volts Between Conductors. Circuits not exceed- heating equipment ing 120 volts,nominal,between conductors shall be permit- Induction and dielectric 665 ted to supply the following: heating equipment Marinas and boatyards 555.19 (1) The terminals of lampholders applied within their volt- Mobile homes, manufactured 550 age ratings homes, and mobile home (2) Auxiliary equipment of electric-discharge lamps parks (3) Cord-and-plug-connected or permanently connected Motion picture and television 530 utilization equipment studios and similar locations Motors, motor circuits, and 430 (C) 277 Volts to Ground. Circuits exceeding 120 volts, controllers nominal, between conductors and not exceeding 277 volts, Pipe organs 650.7 nominal,to ground shall be permitted to supply the following: Recreational vehicles and 551 recreational vehicle parks (1) Listed electric-discharge luminaires Switchboards and panelboards 408.52 (2) Listed incandescent luminaires, where supplied at 120 Theaters, audience areas of 520.41, volts or less from the output of a stepdown autotrans- motion picture and television 520.52, former that is an integral component of the luminaire studios, and similar locations 520.62 and the outer shell terminal is electrically connected to X-ray equipment 660.2, 517.73 a grounded conductor of the branch circuit 70-46 NATIONAL ELECTRICAL.CODE 2008 Edition ARTICLE 210—BRANCH CIRCUITS 210.8 (3) Luminaires equipped with mogul-base screw shell lam- ductors supplying those devices shall be provided at the pholders point at which the branch circuits originate. (4) Lampholders, other than the screw shell type, applied within their voltage ratings 210.8 Ground-Fault Circuit-Interrupter Protection for (5) Auxiliary equipment of electric-discharge tamps Personnel. (6) Cord-and-plug-connected or permanently connected FPN: See 215.9 for ground-fault circuit-interrupter protec- utilization equipment tion for personnel on feeders. (D) 600 Volts Between Conductors. Circuits exceeding (A) Dwelling Units. All 125-volt, single-phase, 15- and 277 volts, nominal, to ground and not exceeding 600 volts, 20-ampere receptacles installed in the locations specified in nominal, between conductors shall be permitted to supply (1) through (8) shalt have ground-fault circuit-interrupter the following: protection for personnel. (1) The auxiliary equipment of electric-discharge lamps (1) Bathrooms mounted in permanently installed luminaires where the (2) Garages, and also accessory buildings that have a floor luminaires are mounted in accordance with one of the located at or below grade Ievel not intended as habit- followin g; able rooms and limited to storage areas, work areas, a. Not less than a height of 6.7 m (22 ft) on poles or and areas of similar use similar structures for the illumination of outdoor ar- (3) Outdoors eas such as highways, roads, bridges, athletic fields, Exception to (3): Receptacles that are not readily acces- or parking lots sible and are supplied by a dedicated branch circuit for b. Not less than a height of 5.5 m (18 ft) on other electric snow-melting or deicing equipment shall be permit- structures such as tunnels ted to be installed in accordance with 426.24. (2) Cord-and-plug-connected or permanently connected (4) Crawl spaces — at or below grade level utilization equipment other than luminaires (3) Luminaires powered from direct-current systems where (5) Unfinished basements — for purposes of this section, unfinished basements are defined as portions or areas of the Iuminaire contains a listed,do-rated ballast that pro- the basement not intended as habitable rooms and lim- vides isolation between the do power source and the ited to storage areas, work areas, and the like lamp circuit and protection from electric shock when changing lamps. • Exception to (5): A receptacle supplying only a perma- nently installed fire alarm or burglar alarm system shall FPN: See 410.138 for auxiliary equipment limitations. not be required to have ground fault circuit-interrupter Exception No. 1 to (B), (C), and (D): For lampholders of protection. infrared industrial heating appliances as provided in FPN: See 760.41(B) and 760.121(H) for power supply 422.14. requirements for fire alarm systems. Exception No. 2 to (B), (C), and(D): For railway proper- Receptacles installed under the exception to ties as described in 110.19. 210.8(A)(5) shall not be considered as meeting the requirements of 210.52(G). (R) Over 600 Volts Between Conductors. Circuits ex- (6) Kitchens—where the receptacles are installed to serve ceeding 600 volts, nominal, between conductors shall be the countertop surfaces permitted to supply utilization equipment in installations (7) Laundry, utility, and wet bar sinks—where the recep- where conditions of maintenance and supervision ensure tacles are installed within 1.8 m (6 ft) of the outside that only qualified persons service the installation. edge of the sink (8) Boathouses 210.7 Branch-Circuit Requirements for Device ConnecR tions and Locations. (B) Other Than Dwelling Units. All 125-volt, single- phase, 15- and 20-ampere receptacles installed in the loca- (A) Receptacle Outlet Location. Receptacle outlets shalt tions specified in (1) through (5) shalt have ground-fault be located in branch circuits in accordance with Part III of circuit-interrupter protection for personnel: Article 210. (1) Bathrooms (B) Multiple Branch Circuits.Where two or more branch (2) Kitchens circuits supply devices or equipment on the same yoke, a (3) Rooftops means to simultaneously disconnect the ungrounded con- (4) Outdoors 2008 Edition NATIONAL.ELEC rRICAL CODE 70-47 210.9 ARTICLE 210—BRANCH CIRCUITS Exception No. I to (3) and (4): Receptacles that are not also serve as a disconnecting means as required by the readily accessible and are supplied from a dedicated following: branch circuit for electric snow-melting or deicing equip- (1) 410.93 for double-pole switched lampholders ment shall be permitted to be installed without GFCI (2) 410.104(B) for electric-discharge lamp auxiliary equip- protection. ment switching devices Exception No. 2 to (4): In industrial establishments only, (3) 422.31(B) for an appliance where the conditions of maintenance and supervision en- (4) 424.20 for a fixed electric space-heating unit sure that only qualified personnel are involved an assured equipment grounding conductor program as specified in (5) 426.51 for electric deicing and snow-melting equipment 590.6(B)(2) shall be permitted for only those receptacle (6) 430.85 for a motor controller outlets used to supply equipment that would create a (7) 430.103 for a motor greater hazard if power is interrupted or having a design that is not Compatible with GFCI protection. 210.11 Branch Circuits Required. Branch circuits for (5) Sinks -- where receptacles are installed within 1.8 m lighting and for appliances, including motor-operated appli- ances, shall be provided to supply the loads calculated in (6 ft) of the outside edge of the Sink. accordance with 220.10. In addition, branch circuits shall Exception No I to (5): In industrial laboratories, recep- be provided for specific loads not covered by 220.10 where tacles used to supply equipment where removal of power required elsewhere in this Code and for dwelling unit loads would introduce a greater hazard shall be permitted to be as specified in 210.11(Q. installed without GFCI protection. Exception No 2 to (5): For receptacles located in patient (A) Number of Branch Circuits. The minimum number care areas of health care facilities other than those covered of branch circuits shall be determined from the total calcu- under 210.8(B)(1), GFCI protection shall not be required. lated load and the size or rating of the circuits used. In all installations, the number of circuits shall be sufficient to (C) Boat Hoists. GFCI protection shall be provided for supply the load served. In no case shall the load on any outlets not exceeding 240 volts that supply boat hoists in- circuit exceed the maximum specified by 220.18. stalled in dwelling unit locations. (B) Load Evenly Proportioned Among Branch Circuits. Where the load is calculated on the basis of volt-amperes 21D.9 Circuits Derived From Autotransformers. Branch per square meter or per square foot,the wiring system up to circuits shall not be derived from autotransformers unless and including the branch-circuit panelboard(s) shall be pro- the circuit supplied has a grounded conductor that is elec- vided to serve not less than the calculated load. This load trically connected to a grounded conductor of the system shall be evenly proportioned among multioutlet branch cir- cuits within the panelboard(s). Branch-circuit overcurrent Exception No. I: An autotransformer shall be permitted devices and circuits shall be required to be installed only to without the connection to a grounded conductor where serve the connected load. transforming from a nominal 208 volts to a nominal 240- volt supply or similarly from 240 volts to 208 volts. (C) Dwelling Units. Exception No. 2: In industrial occupancies, where condi- (1) Small-Appliance Branch Circuits. In addition to the tions of maintenance and supervision ensure that only number of branch circuits required by other parts of this qualified persons service the installation, autotransformers section, two or more 20-ampere small-appliance branch cir- shall be permitted to supply nominal 600-volt loads from cuits shall be provided for all receptacle outlets specified by nominal 480-volt systems, and 480-volt loads from nominal 210.52(B). 600-volt systems, without the connection to a similar (2) Laundry Branch Circuits. In addition to the number grounded conductor, of branch circuits required by other parts of this section, at least one additional 20-ampere branch circuit shall be pro- 21D.10 Ungrounded Conductors Tapped from vided to supply the laundry receptacle outlets) required by Grounded Systems.Two-wire do circuits and ac circuits of 210.52(F). This circuit shall have no other outlets. two or more ungrounded conductors shall be permitted to be tapped from the ungrounded conductors of circuits that (3) Bathroom Branch Circuits. In addition to the number have a grounded neutral conductor. Switching devices in of branch circuits required by other parts of this section, at each tapped circuit shall have a pole in each ungrounded least one 20-ampere branch circuit shall be provided to conductor. All poles of multipole switching devices shall supply bathroom receptacle outlet(s). Such circuits shall manually switch together where such switching devices have no other outlets. 70-48 NATIONAL IMCMICAL CODE 2008 Edition ARTICLE 210—BRANCH CIRCUITS 210.19 Exception: Where the 20-ampere circuit supplies a single (1) General. Branch-circuit conductors shall have an am- bathroom, outlets for other equipment within the same parity not less than the maximum load to be served.Where bathroom shall be permitted to be supplied in accordance a branch circuit supplies continuous loads or any combina- with 210.230)(1) and (A)(2). tion of continuous and noncontinuous loads, the minimum FPN: See Examples D1(a), DI(b), D2(b), and D4(a) in branch-circuit conductor size, before the application of any Annex D. adjustment or correction factors, shall have an allowable ampacity not less than the noncontinuous load plus 210.12 Arc-Fault Circuit-Interrupter Protection. 125 percent of the continuous load. (A) Definition:Arc-Fault Circuit Interrupter(AFCI). A Exception No. 1: Where the assembly, including the over- device intended to provide protection from the effects of current devices protecting the brunch circuit(s), is listed for arc faults by recognizing characteristics unique to arcing operation at 100 percent of its rating, the allowable ampac- and by functioning to de-energize the circuit when an arc ity of the branch circuit conductors shall be permitted to be fault is detected, not less than the scan of the continuous load plus the non- (B) Dwelling Units. All 120-volt, single phase, 15- and continuous lead. 20-ampere branch circuits supplying outlets installed in Exception No. 2: Grounded conductors that are not con- dwelling unit family rooms, dining rooms, living rooms, nected to an overcurrent device shall be permitted to be parlors, libraries, dens, bedrooms, sunrooms, recreation sized at 100 percent of the continuous and noncontinuous rooms, closets, hallways, or similar rooms or areas shall be load protected by a listed arc-fault circuit interrupter, combination-type, installed to provide protection of the FPN No. 1: See 31(}.15 for ampacity ratings of conductors. branch circuit. FAN No. 2: See Part 11 of Article 430 for minimum rating FPN No. 1. For information on types of arc-fault circuit of motor branch-circuit conductors. interrupters. see UL 1699-1999, Standard for Arc-Fault FPN No. 3: See 310.10 for temperature limitation of Circuit Interrupters. conductors. FPN No. 2: See 11.6.3(5) of NFPA 72-'-2007, National FPN No. 4: Conductors for branch circuits as defined in Fire Alarm Code°, for information related to secondary Article 1(X), sized to prevent a voltage drop exceeding power supply requirements for smoke alarms installed in 3 percent at the farthest outlet of power, heating,and light- dwelling units. ing loads, or combinations of such loads, and where the re tare and 760.121(B) for power maximum total voltage drop on both feeders and branch FPN N 3: See 760. circuits to the farthest outlet does not exceed 5 percent, supply requirements for fire alarm systems, provide reasonable efficiency of operation. See FPN No. 2 Exception No. 1: Where RMC, IMC,EMT or steel armored of 215.2(A)(3) for voltage drop on feeder conductors. cable, Type AC, meeting the requirements of 250.118 using (2) Multioutlet Branch Circuits. Conductors of branch metal outlet and junction boxes is installed for the portion circuits supplying more than one receptacle for cord-and- of the branch circuit between the branch-circuit overcur- plug-connected portable loads shall have an ampacity of rent device and the first outlet, it shall be permitted to not less than the rating of the branch circuit. install a combination AFC1 at the first outlet to provide protection for the remaining portion of the branch circuit. (3) Household Ranges and Cooking Appliances. Branch- Exc•eption No. 2: Where a branch circuit to a fire alarm circuit conductors supplying household ranges, wall- system installed in accordance with 760.41(B) and mounted ovens, counter-mounted cooking units, and other 760.121(B) is installed in RMC, IMC, EMT, or steel ar- household cooking appliances shall have an ampacity not mored cable, Type AC, meeting the requirements of less than the rating of the branch circuit and not less than 250.118, with metal outlet and junction boxes, AFCI pro- the maximum load to be served. For ranges of 8-1/4 kW or tection shall be permitted to be omitted more rating, the minimum branch-circuit rating shall be 40 amperes. 210.15 Guest Rooms and Guest Suites. Guest rooms and Exception No. 1: Conductors tapped from a 50-ampere guest suites that are provided with permanent provisions for branch circuit supplying electric ranges, wall-mounted cooking shall have branch circuits installed to meet the electric ovens, and counter-mounted electric cooking units rules for dwelling units. shall have an ampacity of not less than 20 amperes and shall be sufficient for the load to be served. These tap con- II. Branch-Circuit Ratings duc•tors include an*v conductors that are a part of the leads supplied with the appliance that are stnaller than the 210.19 Conductors — Minimum Ampacity and Size. branch-circuit conductors. The taps shall not be longer (A) Branch Circuits Not More Than 600 Volts. than necessary for,servicing the appliance. 2(X)8 Edition NATIONAL ELECTRICAL CODE 70-49 210.20 ARTICLE 210—BRANCH CIRCUITS Exception No. 2: The neutral conductor of a 3-wire branch 210.20 Overcurrent Protection. Branch-circuit conduc- c•ircuit supplying a household electric range, a wall- tors and equipment shall be protected by overcurrent pro- mounted oven, or a counter-mounted cooking unit shall be tective devices that have a rating or setting that complies permitted to be smaller than the ungrounded conductors with 210.20(A) through (D). where the maxims m demand of a range of 8-114-kW or more rating has been calculated according to Column C of Table (A) Continuous and Noncontinuous Loads. Where a 220.55, but such conductor shall have an ampacity of not branch circuit supplies continuous loads or any combina- less than 70 percent of the branch-circuit rating and shall tion of continuous and noncontinuous loads, the rating of not be smaller than 10 AWG. the overcurrent device shall not be less than the noncon- tinuous load plus 125 percent of the continuous load. (4) Other Loads. Branch-circuit conductors that supply Exception: Where the assembly, including the overcurrent loads other than those specified in 210.2 and other than at 100 percent of its rating, the ampere rating of the devices protecting the branch circuit(s), is listed for opera- cooking appliances as covered in 210.19(A)(3) shall have tiv an ampacity sufficient for the loads served and shall not be rt smaller than 14 AWG. overcurrent device shall be permitted to be not less than the sum of the continuous load plus the noncontinuous load. Exception No. 1: Tap conductors shall have an ampacity sufficient for the load served. In addition, they shall have an (B) Conductor Protection. Conductors shall be protected ainpac•ity of not less than 15 for circuits rated less than 40 in accordance with 240.4. Flexible cords and fixture wires amperes and not less than 20 for circuits rated at 40 or 50 shall be protected in accordance with 240.5. amperes and only where these tap conductors supply any of the fallowing loads: (C) Equipment. The rating or setting of the overcurrent protective device shall not exceed that specified in the ap- (a) Individual lampholders or luminaires with taps ex- plicable articles referenced in Table 240.3 for equipment. tending not longer than 450 mm (18 in.) beyond any por- tion of the lampholder or honinaire. (D) Outlet Devices. The rating or setting shall not exceed (b) A luminaire having tap conductors as provided in that specified in 210.21 for outlet devices. 410.117. (c) Individual outlets, other than receptacle outlets, 210.21 Outlet Devices. Outlet devices shall have an am- with taps not over 450 nom (18 in.) long. pere rating that is not less than the load to be served and (d) Infrared lamp industrial heating appliances. shall comply with 210.21(A) and (B). (e) Nonheating leads of deicing and snow-melting (A) Lampholders. Where connected to a branch circuit cables and mats. having a rating in excess of 20 amperes, lampholders shall Exception No. 2: Fixture wires and flexible cords shall be be of the heavy-duty type. Aheavy-duty lampholder shall permitted to be smaller than 14 AWG as permitted by have a rating of not less than 660 watts if of the admedium 240.5. type, or not less than 750 watts if of any other type. (B) Branch Circuits Over 600 Volts. The ampacity of (B) Receptacles. conductors shall be in accordance with 310.15 and 310.60, as applicable. Branch-circuit conductors over 600 volts (1) Single Receptacle on an Individual Branch Circuit. shall be sized in accordance with 210.19(B)(1) or (13)(2). A single receptacle installed on an individual branch circuit shall have an ampere rating not less than that of the branch (1) General.The ampacity of branch-circuit conductors shall circuit. not be less than 125 percent of the designed potential load of utilization equipment that will be operated simultaneously. Exception Nn. 1: A receptacle installed in accordance with 430.81(B). (2) Supervised Installations. For supervised installations, Exception No. 2: A receptacle installed exclusively for the branch-circuit conductor sizing shall be permitted to be de- use of a cord-and-plug-connected are welder shall be permit- termined by qualified persons under engineering supervi- ted to have an ampere rating not less than the minimum sion. Supervised installations are defined as those portions branch-circuit conductor ampacity determined by 630.11(A) of a facility where both of the following conditions are met: for am welders. (1) Conditions of design and installation are provided un- FPN: See the definition of receptacle in Article 100. der engineering supervision. (2) Qualified persons with documented training and expe- (2) Total Cord-and-Plug-Connected Load. Where con- rience in over 600-volt systems provide maintenance, nected to a branch circuit supplying two or more recep- monitoring, and servicing of the system. tacles or outlets, a receptacle shall not supply a total cord- 70-50 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 210—BRANCH CIRCUITS 210.25 Table 210.21(B)(2) Maximum Cord-and-Plug-Connected Exception: The sntall-appliance branch circuits, latntdrr Load to Receptacle branch circuits, and bathroom branch circuits required in a dwelling unit(s) kv 210.11(C)(1), (C)(2), and (0(3) shall Circuit Rating Receptacle Rating Maximum Load supphy only the receptacle outlets specified in that section. (Amperes) (Amperes) (Amperes) (1) Cord-and-Plug-Connected Equipment Not Fastened 15 or 2{t ]5 12 20 20 lh in Place. The rating of any one cord-and-plug-connected 30 30 24 utilization equipment not fastened in place shall not exceed 80 percent of the branch-circuit ampere rating. and-plug-connected load in excess of the maximum (2) Utilization Equipment Fastened in Place. The total specified in Table 210.21(B)(2), rating of utilization equipment fastened in place, other than luminaires, shall not exceed 50 percent of the branch- (3) Receptacle Ratings. Where connected to a branch cir- circuit ampere rating where lighting units, cord-and-plug- cuit supplying two or more receptacles or outlets, recep- connected utilization equipment not fastened in place, or tacle ratings shall conform to the values listed in Table both, are also supplied. 210.21(6)(3), or where larger than 50 amperes, the recep- tacle rating shall not be less than the branch-circuit rating. (B) 30-Ampere Branch Circuits.A 30-ampere branch cir- cuit shall be permitted to supply fixed lighting units with Exception No. 1: Receptacles for one or more cord-and- heavy-duty lampholders in other than a dwelling unit(s) or phcg-connected arc welders shall be permitted to have ant- utilization equipment in any occupancy.A rating of any one pere ratings not less than the mini nlan branch-circuit coil- cord-and-plug-connected utilization equipment shall not ductor antpacit}• permitted b�• 630.11(A) or (B) as exceed 80 percent of the branch-circuit ampere rating. applicable for arc welders. Exception No. 2: The ampere rating of a receptacle in- (C) 40- and 50-Ampere Branch Circuits. A 40- or 50- ampere branch circuit shall be permitted to supply cooking stalled for electric discharge lighting shall be pemitted to appliances that are fastened in place in any occupancy. In be based nn 410.62(C1. other than dwelling units, such circuits shall be permitted to Table 210.21(6)(3) Receptacle Ratings for Various Size supply fixed lighting units with heavy-duty lampholders, Circuits infrared heating units, or other utilization equipment. Circuit Raking Receptacle Rating (D) Branch Circuits Larger Than 50 Amperes. Branch (Amperes) (Amperes) circuits larger than 50 amperes shall supply only nonlight- ing outlet loads. 15 Not over 15 20 15 or 20 210.24 Branch-Circuit Requirements—Summary. The 30 30 requirements for circuits that have two or more outlets or Sp 40 5 r 50 receptacles, other than the receptacle circuits of 210.11(C)(1} and (C)(2), are summarized in Table 210.24. This table pro- vides only a summary of minimum requirements.See 210.19, (4) Range Receptacle Rating. The ampere rating of a 210.20, and 210.21 for the specific requirements applying to range receptacle shall be permitted to be based on a single branch circuits. range demand load as specified in Table 220.55. 210.25 Branch Circuits in Buildings with More Than 210.23 Permissible Loads. In no case shall the load ex- One Occupancy. ceed the branch-circuit ampere rating.An individual branch (A) Dwelling Unit Branch Circuits. Branch circuits in circuit shall be permitted to supply any load for which it is each dwelling unit shall supply only loads within that dwelling rated. A branch circuit supplying two or more outlets or unit or loads associated only with that dwelling unit. receptacles shall supply only the loads specified according to its size as specified in 210.23(A) through (D) and as (B) Common Area Branch Circuits. Branch circuits re- summarized in 210.24 and Table 210.24. quired for the purpose of lighting, central alarm, signal, communications, or other needs for public or common ar- (A) 15- and 20-Ampere Branch Circuits. A 15- or 20- eas of a two-family dwelling, a multifamily dwelling, or a ampere branch circuit shall be permitted to supply lighting multi-occupancy building shall not be supplied from equip- units or other utilization equipment, or a combination of ment that supplies an individual dwelling unit or tenant both, and shall comply with 210.23(A)(1) and (A)(2). space. 2008 Edition NATIONAL ELECTRICAL CODE 70-51 210.50 ARTICLE 210—BRANCH CIRCUITS Table 210.24 Summary of Branch-Circuit Requirements Circuit Rating 15 A 20 A 30 A 40 A 50 A Conductors (min. size): Circuit wires' 14 12 10 8 6 Taps 14 14 14 12 12 Fixture wires and cords see 240.5 Overcurrent Protection 15 A 20 A 30A 40 A 50 A Outlet devices: Lampholders Any type Any type Heavy duty Heavy duty Heavy duty permitted Receptacle rating 2 15 max.A 15 or 20 A 30 A 40 or 50 A 50 A Maximum Load 15 A 20 A 30 A 40 A 50A Permissible load See 210.23(A) See 210.23(A) See 210.23(B) See 210.23(C) See 210.23(C) 'These gauges are for copper conductors. =For receptacle rating or cord-connected electric-discharge luminaires, see 410.62. III. Required Outlets such permanently installed heaters. Such receptacle outlets 210.50 General. Receptacle outlets shall be installed as shall not be connected to the heater circuits. specified in 210.52 through 210.63. FPN: Listed baseboard heaters include instructions that may not permit their installation below receptacle outlets. (A) Cord Pendants.A cord connector that is supplied by a permanently connected cord pendant shall be considered a (A) General Provisions. In every kitchen, family room, receptacle outlet. dining room, living room, parlor, library, den, sunroom, bedroom, recreation room, or similar room or area of (B) Cord Connections. A receptacle outlet shall be in- dwelling units,receptacle outlets shall be installed in accor- stalled wherever flexible cords with attachment plugs are dance with the general provisions specified in 210.52(A)(1) used. Where flexible cords are permitted to be permanently through (A)(3). connected, receptacles shall be permitted to be omitted for (1} Spacing. Receptacles shall be installed such that no such cords. point measured horizontally along the floor line in any wall (C) Appliance Receptacle Outlets. Appliance receptacle space is more than 1.8 m (6 ft) from a receptacle outlet. outlets installed in a dwelling unit for specific appliances, such as laundry equipment, shall be installed within 1.8 m (2) Wall Space. As used in this section, a wall space shall (b ft) of the intended location of the appliance. include the following: (1) Any space 600 mm (2 ft) or more in width (including 210.52 Dwelling Unit Receptacle Outlets. This section space measured around comers) and unbroken along the provides requirements for 125-volt, 15- and 20-ampere re- floor line by doorways, fireplaces, and similar openings ceptacle outlets. The receptacles required by this section (2) The space occupied by fixed panels in exterior walls, shall be in addition to any receptacle that is: excluding sliding panels (1) Part of a luminaire or appliance, or (3) The space afforded by fixed room dividers such as free- (2) Controlled by a wall switch in accordance with standing bar-type counters or railings 210.70(A)(1), Exception No. 1, or (3) Dated within cabinets or cupboards, or (3) Floor Receptacles. Receptacle outlets in floors shall not be counted as part of the required number of receptacle (4) Located more than 1.7 m (51h f-0 above the floor outlets unless located within 450 mm (18 in.) of the wall. Permanently installed electric baseboard heaters equipped (B) Small Appliances. with factory-installed receptacle outlets or outlets provided as a separate assembly by the manufacturer shall be permitted as (1) Receptacle Outlets Served. In the kitchen, pantry, the required outlet or outlets for the wall space utilized by breakfast room, dining room, or similar area of a dwelling 70-52 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 210—BRANCH CIRCUITS 210.52 unit, the two or more 20-ampere small-appliance branch Exception: Receptacle outlets shall not be required on a circuits required by 210.11(C)(1) shall serve all wall and wall directly behind a range, counter-mounted Cooking floor receptacle outlets covered by 210.52(A), all counter- unit, or sink in the installation described in Figure top outlets covered by 210.52(C), and receptacle outlets for 210.52(C)(1). refrigeration equipment, Exception No, 1: hl addition to the required receptacles Outlet within Space exempt from wall p q p Outlet within specified bti� 210.52, switched receptacles supplied from a 600 mm(24 in.} line it X<300 mm(12 in.) 600 mm(24 in.) general-purpose branch circuit as defined in 210.70(A)(1), Exception No, 1, .shall be permitted. X Exception No. 2: The receptacle outlet for refrigeration equipment shall be permitted to be supplied front an indi- vidual branch circuit rated 15 amperes or greater. (2) No Other Outlets. The two or more small-appliance branch circuits specified in 210.52(B)(1) shall have no other outlets. Exception No. 1: A receptacle installed solely for the elec- Range,counter-mounted cooking unit extending trical supply to and support of an electric clock in anti' of' from face of counter the roonis specified in 210.52(B)(1). Exception No. 2: Receptacles installed to provide power Space exempt from wall line Outlet within 600 mm(24 in.)—r for supplemental equipment and lighting on gas fired if X<450 mm(18 in.) ranges, averts, or counter-mounted cooking units. (3) Kitchen Receptacle Requirements. Receptacles in- stalled in a kitchen to serve countertop surfaces shall be X supplied by not fewer than two small-appliance branch cir- cuits, either or both of which shall also be permitted to supply receptacle outlets in the same kitchen and in other rooms specified in 210.52(B)(1). Additional small- appliance branch circuits shall be permitted to supply re- ceptacle outlets in the kitchen and other rooms specified in Outlet within 600 mm 210.52(B)(1). No small-appliance branch circuit shall serve (24 in.) more than one kitchen. (C) Countertops. In kitchens, pantries, breakfast rooms, dining rooms, and similar areas of dwelling units, recep- tacle outlets for countertop spaces shall be installed in ac- Range,counter-mounted cooking unit mounted in corner cordance with 210.52(C)(1) through (C)(5). Figure 210.52(C)(1) Determination of Area Behind a Range, Where a range, counter-mounted cooking unit, or sink or Counter-Mounted Cooking Unit or Sink. is installed in an island or peninsular countertop and the width of the countertop behind the range, counter-mounted cooking unit, or sink is less than 300 mm (12 in.), the (2) island Countertop Spaces. At least one receptacle range, counter-mounted cooking unit, or sink is Considered shall be installed at each island countertop space with a to divide the countertop space into two separate countertop long dimension of m ( in.) or greater and a short dimension of 300 mm spaces as defined in 210.52(C)(4).Each separate countertop (112 2 i n.}) or greater. space shall comply with the applicable requirements in (3) Peninsular Countertop Spaces. At least one recep- 210.52(C). tacle outlet shall be installed at each peninsular countertop (1) Wall Countertop Spaces. A receptacle outlet shall he space with a long dimension of 600 mm (24 in.) or greater installed at each wall countertop space that is 300 mm and a short dimension of 300 mm (12 in.) or greater. A (12 in.) or wider. Receptacle outlets shall be installed so peninsular countertop is measured from the connecting that no point along the wall line is more than 600 mm edge. (24 in.) measured horizontally from a receptacle outlet in (4) Separate Spaces. Countertop spaces separated by that space. rangetops, refrigerators, or sinks shall be considered as 2008 Edition NATIONAL ELECTRICAL CODE 70-53 210.60 ARTICLE 210---BRANCH CIRCUITS separate countertop spaces in applying the requirements of shall not be Iocated, more than 2.0 m (61/2 ft) above the 210.52(C)(1), (C)(2), and (C)(3). balcony, deck, or porch surface. (5) Receptacle Outlet Location. Receptacle outlets shall Exception to (3): Balconies decks, or porches with a us- be located above,but not more than 500 mm (20 in.)above, able area of less than 1.86 rn2 (20 ftz) are not required to the countertop. Receptacle outlets rendered not readily ac- have a receptacle installed cessible by appliances fastened in place, appliance garages, sinks, or rangetops as covered in 210.52(C)(1), Exception, (F) Laundry Areas. In dwelling units, at least one recep- or appliances occupying dedicated space shall not be con- tacle outlet shall be installed for the laundry. sidered as these required outlets. Exception No. 1: In a dwelling unit that is an apartment Exception to(5): To comply with the conditions specified in or living area in a multifamily building where laundry fa- (1) or (2), receptacle outlets shall be permitted to be cilities are provided on the premises and are available to mounted not more than 300 mm (12 in.) below the counter- all building occupants, a laundry receptacle shall not be top. Receptacles mounted below a countertop in accor- required dance with this exception shall not be located where the Exception No. 2: In other than one fantily dwellings where countertop extends more than 150 mm (6 in.) beyond its laundry facilities are not to be installed or permitted, a support base. laundry receptacle .shall not be required. (1) Construction for the pikysically impaired (2) On island and peninsular countertops where the coon- (G) Basements and Garages. For aone-family dwelling, the following provisions shall apply: tertop is fiat across its entire surface (no backsplashes, dividers, etc.) and there are no means to mount a re- (1) At least one receptacle outlet, in addition to those for ceptacle within 500 nun (20 in.) above the countertop, specific equipment, shall be installed in each basement, such as an overhead cabinet in each attached garage, and in each detached garage with electric power. (D) Bathrooms. In dwelling units, at least one receptacle (2) Where a portion of the basement is finished into one or outlet shall be installed in bathrooms within 900 mm (3 ft) more habitable rooms, each separate unfinished portion of the outside edge of each basin. The receptacle outlet shall have a receptacle outlet installed in accordance shall be located on a wall or partition that is adjacent to the with this section. basin or basin countertop, or installed on the side or face of the basin cabinet not more than 300 mm(12 in.)below the (H) Hallways. In dwelling units, hallways of 3.0 m (10 ft) countertop. or more in length shall have at least one receptacle outlet. As used in this subsection, the hall length shall be con- (E) Outdoor Outlets. Outdoor receptacle outlets shall be sidered the length along the centerline of the hall without installed in accordance with (E)(1) through (E)(3). [See passing through a doorway. 210.8(A)(3)•J 210.60 Guest Rooms, Guest Suites, Dormitories, and (1) One-Family and T-wo-Family Dwellings. For a one- Similar Occupancies. family dwelling and each unit of a two-family dwelling that is at grade level, at least one receptacle outlet accessible (A) General.Guest rooms or guest suites in hotels,motels, while standing at grade level and located not more than sleeping rooms in dormitories, and similar occupancies 2.0 m (61/2 ft) above grade shall be installed at the front and shall have receptacle outlets installed in accordance with back of the dwelling. 210.52(A) and 210.52(D). Guest rooms or guest suites pro- vided with permanent provisions for cooking shall have (2) Multifamily Dwellings. For each dwelling unit of a receptacle outlets installed in accordance with all of the multifamily dwelling where the dwelling unit is located at applicable rules in 210.52. grade level and provided with individual exterior entrance/egress, at least one receptacle outlet accessible (B) Receptacle Placement. In applying the provisions of from grade level and not more than 2.0 m (61/2 ft) above 210.52(A), the total number of receptacle outlets shall not grade shall be installed. be less than the minimum number that would comply with the provisions of that section.These receptacle outlets shall (3) Balconies,Decks,and Porches.Balconies, decks,and be permitted to be located conveniently for permanent fur- porches that are accessible from inside the dwelling unit niture layout.At least two receptacle outlets shall be readily shall have at least one receptacle outlet installed within the accessible. Where receptacles are installed behind the bed, perimeter of the balcony, deck, or porch. The receptacle the receptacle shall be located to prevent the bed from 70-5¢ NATIONAL ELECTRICAL CODE 2008 Edition ARTICL.F 215—FEEDERS 215.1 contacting any attachment plug that may be installed or the with grade level access. A vehicle door in a garage shall not receptacle shall be provided with a suitable guard. be considered as an outdoor entrance or exit. (c) Where one or more lighting outlet(s) are installed 210.62 Show Windows. At least one receptacle outlet for interior stairways, there shall be a wall switch at each shall be installed within 450 mm (18 in.) of the top of a floor level, and landing level that includes an entryway, to show window for each 3.7 linear m (12 linear ft) or major control the lighting outlet(s) where the stairway between fraction thereof of show window area measured horizon- floor levels has six risers or more. tally at its maximum width. Exception to (A)(2)(a), (A)(2)(b), and (A)(2)(c•): In hall- ways, in stairways, and at outdoor entrances, remote, c•en- 210.63 Heating, Air-Conditioning, and Refrigeration tral, or autonunic and of ligghting shall be permitted. Equipment Outlet. A 125-volt, single-phase, 15- or 20- ampere-rated receptacle outlet shall be installed at an ac- (3) Storage or Equipment Spates. For attics, underfloor cessible location for the servicing of heating, air- spaces, utility rooms, and basements, at least one lighting conditioning, and refrigeration equipment. The receptacle outlet containing a switch or controlled by a wall switch shall be located on the same level and within 7.5 m (25 ft) shall be installed where these spaces are used for storage or of the heating, air-conditioning, and refrigeration equip- contain equipment requiring servicing.At least one point of ment. The receptacle outlet shall not be connected to the control shall be at the usual point of entry to these spaces. load side of the equipment disconnecting means. The lighting outlet shall be provided at or near the equip- Exception: A receptacle outlet shall not be required at one- merit requiring servicing, and ttvo-fantlly dwelli,g=•s for flte s'enice of evapnrculve (B) Guest Rooms or Guest Suites. In hotels, motels, or coolers. similar occupancies, guest rooms or guest suites shall have at least one wall switch--controlled lighting outlet installed FPN: See 210.8 for ground-fault circuit-interrupter in every habitable room and bathroom. requirements. Exception No. 1: In other than bathrooms and kitchens 210.70 Lighting Outlets Required. Lighting outlets shall where provided, one or more receptacles controlled by a be installed where specified in 210.70(A), (B), and (C). x•all switch shall be permitted in lieu of lkghting outlets. Exception No. 2: Lighting outlets shall be permitted to he (A) Dwelling Units, In dwelling units, [fighting outlets controlled by occupancy sensors that are (1) in addition to shall be installed in accordance with 210.70(A)(1), (A)(2), wall switches or (2) located at a customary wall switch and (A){3}• location and equipped with a manual override that allows (1) Habitable Rooms. At least one wall switch–controlled the sensor to function as a wall switch. lighting outlet shall be installed in every habitable room (C) Other Than Dwelling Units.For attics and underfloor and bathroom. spaces containing equipment requiring servicing, such as Exception No. 1: !n other than kitchens and bathrooms, heating, air-conditioning, and refrigeration equipment, at one or more receptacles controlled by a wall switch shall least one lighting outlet containing a switch or controlled be permitted in lieu of'lig=hting outlets. by a wall switch shall be installed in such spaces. At least Exception No. 2: Lighting outlets shall be permitted to be one point of control shall be at the usual point of entry to controlled bti• occupancy sensors that are (1) in addition to these spaces. The lighting outlet shall be provided at or wall switches or (2) located at a customary wall switch near the equipment requiring servicing. location and equipped with a manual override that will allow the sensor to frazction as a wall.switch. (2) Additional Locations. Additional lighting outlets shall ARTICLE 215 be installed in accordance with (A)(2)(a), (A)(2)(b), and (A)(2)(c). Feeders (a) At least one wall switch--controlled lighting outlet 215.1 Scope. This article covers the installation re uire- shall be installed in hallways, stairways, attached garages, q menu, overcurrent protection requirements, minimum size, and detached garages with electric power. (b) For dwelling units, attached garages, and detached and ampacity of conductors for feeders supplying branch- garages with electric power, at least one wall switch-- circuit loads. controlled lighting outlet shall be installed to provide illu- Exception: Feeders for electrolytic cells as covered in mination on the exterior side of outdoor entrances or exits 665.3(C)(1) and (C)(4). 2008 Edition NATIONAL ELECTRICAL CODE 70-55 215.2 ARTICLE 215—FEEDERS 215.2 Minimum Rating and Size. grounded conductors are run in parallel. Feeder conductors (A) Feeders Not More Than 600 Volts. over 600 volts shall be sized in accordance with 215.2(B)(1), (B)(2), or (13)(3). (1) General. Feeder conductors shall have an ampacity not less than required to supply the load as calculated in Part s (1) Feeders Supplying Transformers. The ampacity of I1I, IV, and V of Article 220. The minimum feeder-circuit feeder conductors shall not be less than the sum of the conductor size, before the application of any adjustment or nameplate ratings of the transformers supplied when only correction factors, shall have an allowable ampacity not transformers are supplied. less than the noncontinuous load plus 125 percent of the (2) Feeders Supplying Transformers and Utilization continuous load. Equipment.The ampacity of feeders supplying a combina- Exception No. 1: Where the assemble, including the over- tion of transformers and utilization equipment shall not be current devices protecting the feeder(s), is listed far opera- less than the sum of the nameplate ratings of the transform- tion at 100 percent of its rating, the allowable ampacity of ers and 125 percent of the designed potential load of the the feeder conductors shall be permitted to be not less than utilization equipment that will be operated simultaneously, the suet of the continuous load plus the noncontinuous load (3) Supervised Installations. For supervised installations, feeder conductor sizing shall be permitted to be determined Exception No. 2: Grounded conductors that are not con- by qualified persons under engineering supervision. Super- nected to an overeurrent device shall be permitted to be vssed installations are defined as those portions of a facility sued at 100 percent of the continuous and noncontinuous load where all of the following conditions are met: (1) Conditions of design and installation are provided un- The size of the feeder circuit grounded conductor shall der engineering supervision. not be smaller than that required by 250.122, except that 250.122(F) shall not apply where grounded conductors are (2) Qualified persons with documented training and expe- rience in over 600-volt systems provide maintenance, run in parallel. Additional minimum sizes shall be as specified in monitoring, and servicing of the system, 215.2(A)(2) and (A)(3) under the conditions stipulated. 215.3 Overcurrent Protection. Feeders shall be protected (2) Ampacity Relative to Service Conductors. The against overcurrent in accordance with the provisions of feeder conductor ampacity shall not be less than that of the Part i of Article 240. Where a feeder supplies continuous service conductors where the feeder conductors carry the loads or any combination of continuous and noncontinuous total load supplied by service conductors with an ampacity loads, the rating of the overcurrent device shall not be less of 55 amperes or less. than the noncontinuous load plus 125 percent of the can- (3) Individual Dwelling Unit or Mobile Home Conduc- tinuous load. tors. Feeder conductors for individual dwelling units or Exception No. 1: Where the assembly, including the over- mobile homes need not be larger than service conductors. current devices protecting the feeder(s), is listed for opera- Paragraph M0.15(B)(6) shall be permitted to be used for tion at 100 percent of its rating, the ampere rating of the conductor size. overcurrent device shall be permitted to be not less than the FPN No. 1: See Examples D1 through DI I in Annex D. sum of the continuous load plus the noncontinuous load. FPN No. 2: Conductors for feeders as defined in Article Exception No. 2: Overcurrew protection forfeeders over 600 100, sized to prevent a voltage drop exceeding 3 percent at volts, nontinal, shall comply with Part XI of Article 240. the farthest outlet of power, heating, and lighting loads, or combinations of such loads, and where the maximum total voltage drop on both feeders and branch circuits to the 215.4 Feeders with Common Neutral Conductor. farthest outlet does not exceed 5 percent, will provide rea- sonable efficiency of operation. (A) Feeders with Common Neutral. Up to three sets of FPN No. 3: See 210.19{A}, FPN No. 4, for voltage drop 3-wire feeders or two sets of 4-wire or 5-wire feeders shall be permitted to utilize a common neutral. for branch circuits. (B) Feeders over 600 Volts. The ampacity of conductors (B) In Metal Raceway or Enclosure.Where installed in a shall be in accordance with 310.15 and 310.60 as appli- metal raceway or other metal enclosure, all conductors of cable. Where installed, the size of the feeder-circuit all feeders using a common neutral conductor shall be en- grounded conductor shall not be smaller than that required closed within the same raceway or other enclosure as re- by 250.122, except that 250.122(F) shall not apply where quired in 300.20. 70-56 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 220—BRANCH-CIRCUIT, FEEDER.AND SERVICE CALCULATIONS 220.3 215.5 Diagrams of Feeders. If required by the authority Exception No. 1: An autotransfornter shall be permitted having jurisdiction, a diagram showing feeder details shall without the connection to a grounded conductor where be provided prior to the installation of the feeders. Such a transforming from a nominal 208 volts to a noininal 240- diagram shalt show the area in square feet of the building volt supply or shnilarly f znn 240 volts to 208 volts. or other structure supplied by each feeder, the total calcu- Exception No. 2: In industrial occupancies, it-here c•ondi- lated load before applying demand factors, the demand fac- tions of maintenance and supervision ensure that o,lv tors used, the calculated load after applying demand fac- qualified persons service the installation, autotransformers tors, and the size and type of conductors to be used. shall be permitted to supply nominal 600-volt loads from nominal 480-volt sys•te,ns, and 480-volt loads from nominal 215.6 Feeder Equipment Grounding Conductor. Where 600-volt systems, without the connection to a similar a feeder supplies branch circuits in which equipment grounded conductor. grounding conductors are required, the feeder shall include or provide an equipment grounding conductor in accor- 215.12 Identification for Feeders. dance with the provisions of 250.134, to which the equip- ment grounding conductors of the branch circuits shall be (A) Grounded Conductor. The grounded conductor of a connected. Where the feeder supplies a separate building or feeder shall be identified in accordance with 200.6. structure, the requirements of 250.32(B) shall apply. (B) Equipment Grounding Conductor. The equipment 215.7 Ungrounded Conductors Tapped from Grounded grounding conductor shall be identified in accordance with 250.119. Systems. Two-wire do circuits and ac circuits of two or more ungrounded conductors shall be permitted to be tapped (C) Ungrounded Conductors. Where the premises wiring from the ungrounded conductors of circuits having a grounded system has feeders supplied from more than one nominal neutral conductor. Switching devices in each tapped circuit voltage system, each ungrounded conductor of a feeder shall have a pole in each ungrounded conductor, shall be identified by phase or line and system at all termi- nation, connection, and splice points. The means of identi- 215.9 Ground-Fault Circuit-Interrupter Protection for fication shall be permitted to be by separate color coding, Personnel. Feeders supplying 15- and 20-ampere recep- marking tape, tagging, or other approved means. The tacle branch circuits shall be permitted to be protected by a method utilized for conductors originating within each ground-fault circuit interrupter in lieu of the provisions for feeder panelboard or similar feeder distribution equipment such interrupters as specified in 210.8 and 590.6(A). shall be documented in a manner that is readily available or shall be permanently posted at each feeder panelboard or 215.10 Ground-Fault Protection of Equipment. Each similar feeder distribution equipment. feeder disconnect rated 1000 amperes or more and installed on solidly grounded wye electrical systems of more than 150 volts to ground, but not exceeding 600 volts phase-to- phase, shall be provided with ground-fault protection of equipment in accordance with the provisions of 230,95. ARTICLE 220 FPN: For buildings that contain health care occupancies. Branch-Circuit, Feeder,and Service Calculations see the requirements of 517.17, Etception Nn. 1: The provisions qf'this section shall not i. General apply to a disconnecting means for a continuous industrial process where a nororderly shutdown will introduce addi- 220.1 Scope. This article provides requirements for calcu- tional or increased hazards• lating branch-circuit, feeder, and service loads. Part I pro- Exception No. 2: The provisions of this section shall not vides for general requirements for calculation methods. Part apply if'ground fault protection of equipment is provided on 11 provides calculation methods for branch-circuit loads. Parts the supply side of the feeder and on the load side of any III and IV provide calculation methods for feeders and ser- transformer supplying the feeder. vices. Part V provides calculation methods for farms. FPN: See Figure 220.1 for infi)rmation on the organization 215.11 Circuits Derived from Autotransformers. Feed- of Article 220. ers shall not be derived from autotranslbrmers unless the system supplied has a grounded conductor that is electri- 220.3 Application of Other Articles. In other articles cally connected to a grounded conductor of the system sup- applying to the calculation of loads in specialized applica- plying the autotransformer, tions, there are requirements provided in Table 220.3 that 2008 Edition NATIONAL ELECTRICAL CODE 70-57 220.5 ARTICLE 220-BRANCH-CIRCUIT,FEEDER AND SERVICE CALCULATIONS are in addition to, or modifications of, those within this Part I General article. 220.5 Calculations. Part II Branch-circuit load calculations (A) Voltages. Unless other voltages are specified, for pur- poses of calculating branch-circuit and feeder loads, nomi- Part IV nal system voltages of 120, 1201240, 208Y/120, 240, 347, Part III 224.61 Optional 480Y/277, 480, 600Y1347, and 600 volts shall be used. Feeder and Neutral feeder and service load Loads service load calculations (B) Fractions of an Ampere.Where calculations result in calculations a fraction of an ampere that is less than 0.5, such fractions shall be permitted to he dropped. Farm dwellings Farm dwellings only only It. Branch-Circuit Load Calculations 220.10 General. Branch-circuit loads shall be calculated Part V Farm load calculations as shown in 220.12, 220.14, and 220.16. Figure 220.1 Bratach-Circuit,Feeder,and Service Calculation 220,12 Lighting Load for Specified Occupancies. A unit Methods. load of not less than that specified in Sable 220.12 for Table 220.3 Additional Load Calculation References Calculation Article Section (or Part) Air-conditioning and refrigerating equipment, branch-circuit 440 Pan 1V conductor sizing Cranes and hoists, rating and size of conductors 610 610.14 Electric welders, ampacity calculations 630 630.11, 630.31 Electrically driven or controlled irrigation machines 675 675.7(A), 675.22(A) Electrified truck parking space 626 Electrolytic cell lines 668 668.3(C) Electroplating, branch-circuit conductor sizing 669 669.5 Elevator feeder demand factors 620 620.14 Fire pumps, voltage drop (mandatory calculation) 695 695.7 Fixed electric heating equipment for pipelines and vessels, 427 427.4 branch-circuit sizing Fixed electric space-heating equipment, branch-circuit sizing 424 424.3 Fixed outdoor electric deicing and snow-melting equipment, 426 426.4 branch-circuit sizing Industrial machinery, supply conductor sizing 670 670.4(A) Marinas and boatyards, feeder and service load calculations 555 555.12 Mobile homes, manufactured homes, and mobile home parks, 550 550.18(B) total load for determining power supply Mobile homes, manufactured homes, and mobile home parks, 550 550.31 allowable demand factors for park electrical wiring systems Motion picture and television studios and similar locations-- 530 530.19 sizing of feeder conductors for television studio sets Motors, Feeder demand factor 430 430.26 Motors, multimotor and combination-load equipment 430 430.25 Motors, several motors or a motor(s) and other load(s) 430 430.24 Over 600-volt branch-circuit calculations 210 210.19(B) Over 600-volt feeder calculations 215 215.2(B) Phase converters, conductors 455 455.6 Recreational vehicle parks, basis of calculations 551 551.73(A) Sensitive electrical equipment, voltage drop (mandatory 647 647.4(D) calculation) Solar photovoltaic systems, circuit sizing and current 690 690.8 Storage-type water heaters 422 422.11(E) Theaters, stage switchboard feeders 520 520.27 70-.58 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 220—BRANCH-CIRCUIT,FEEDER,AND SERVICE CALCULATIONS 220.14 occupancies specified therein shall constitute the minimum (L),the loads shown being based on nominal branch-circuit lighting load. The floor area for each floor shall be calcu- voltages. lated from the outside dimensions of the building, dwelling unit, or other area involved. For dwelling units, the calcu- Exception: The loads of outlets serving .switchboards and lated floor area shall not include open porches, garages, or nvitching frames in telephone exchanger shall be waived unused or unfinished spaces not adaptable for future use, ,from the calculations. FPN: The unit values herein are based on minimum load (A) Specific Appliances or Loads.An outlet for a specific conditions and 100 percent power factor and may not pro- appliance or other load not covered in 220.14(B) through vide sufficient capacity for the installation contemplated. (L) shall be calculated based on the ampere rating of the appliance or load served, Table 220.12 General Lighting Loads by Occupancy (g) Electric Dryers and Household Electric Cooking Appliances. Load calculations shall be permitted as speci- fied in 220.54 for electric dryers and in 220.55 for electric Volt-Amperes Volt-Amperes ranges and other cooking appliances. per Square per Square 'lope of Occupancy Meter Foot (C) Motor Loads. Outlets for motor loads shall be calcu- lated in accordance with the requirements in 430.22, Armories and auditoriums 11 1 430.24, and 440.6. Banks 39" 311," Barber shops and beauty 33 3 (D) Luminaires. An outlet supplying luminaire(s) shall be parlors calculated based on the maximum volt-ampere rating of the Churches I I I equipment and lamps for which the luminaires Clubs 22 2 { } is rated. Court rooms 22 2 Dwelling units" 33 3 (E) Heavy-Duty Lampholders. Outlets for heavy-duty Garages—commercial 6 112 lampholders shall be calculated at a minimum of 600 volt- (storage) amperes. Hospitals 22 2 Hotels and motels, including 22 2 (F) Sign and Outline Lighting. Sign and outline lighting apartment houses without outlets shall be calculated at a minimum of 1200 volt- provision for cooking by tenants' amperes for each required branch circuit specified in Industrial commercial (loft) 22 2 600.5(A). buildings (G) Show Windows. Show windows shall be calculated in Lodge rooms 17 11/ Office buildings 39" 3112" accordance with either of the following: Restaurants 22 2 (1) The unit load per outlet as required in other provisions Schools 33 3 of this section Stores 33 3 Warehouses (storage) 3 y; (2) At 200 volt-amperes per 300 mm (1 ft) of show In any of the preceding window occupancies except one-family dwellings and (H) Fixed Multioutlet Assemblies. Fixed multioutlet as- individual dwelling units of sembiies used in other than dwelling units or the guest two-family and multifamily rooms or guest suites of hotels or motels shall be calculated dwellings: in accordance with (H)(1) or (H)(2). For the purposes of Assembly halls and I l 1 P P auditoriums this section, the calculation shall be permitted to be based Halls, corridors, closets, 6 1/2 on the portion that contains receptacle outlets. stairways (1) Where appliances are unlikely to be used simulta- Storage spaces 3 /a neously, each 1.5 m (5 ft) or fraction thereof of each 'See 220.1411). separate and continuous length shall be considered as ''See 220.14(K). one outlet of not less than 180 volt-amperes. (2) Where appliances are likely to be used simultaneously, each 300 mm (I ft) or fraction thereof shall be consid- 22U.14 Other Loads --All Occupancies. In all occupan- ered as an outlet of not less than 180 volt-amperes. cies, the minimum load for each outlet for general-use receptacles and outlets not used for general. illumination (I) Receptacle Outlets. Except as covered in 220.14(J) shall not be less than that calculated in 220.14(A) through and (K), receptacle outlets shall be calculated at not less 2008 Edition NATIONAL ELECTRICAL CODE 70-59 220.16 ARTICLE 220—BRANCH-CIRCUIT,FEEDER,AND SERVICE CALCULATIONS than 180 volt-amperes for each single or for each multiple apply. For circuits supplying loads consisting of motor- receptacle on one yoke. A single piece of equipment con- operated utilization equipment that is fastened in place and sisting of a multiple receptacle comprised of four or more has a motor larger than %hp in combination with other loads, receptacles shall be calculated at not less than 90 volt-amperes the total calculated load shall be based on 125 percent of the per receptacle. This provision shall not be applicable to the largest motor load plus the sum of the other loads. receptacle outlets specified in 210.11(C)(1) and (C)(2). (B) Inductive Lighting Loads. For circuits supplying (J) Dwelling Occupancies. In one-family, two-family, and lighting units that have ballasts, transformers, or autotrans- multifamily dwellings and in guest rooms or guest suites of formers, the calculated load shall be based on the total hotels and motels, the outlets specified in (J)(1), (J)(2), and ampere ratings of such units and not on the total watts of (1)(3) are included in the general lighting load calculations the lamps. of 220.12. No additional load calculations shall be required for such outlets. (C) Range Loads. It shall be permissible to apply demand (1) All general-use receptacle outlets of 20-ampere rating factors for range loads in accordance with Table 220.55, or less, including receptacles connected to the circuits including Note 4. in 210.11(C)(3) (2) The receptacle outlets specified in 210.52(E) and (G) III, Feeder and Service Load Calculations (3) The lighting outlets specified in 210.70(A) and (B) 220.40 General The calculated load of a feeder or service (K) Banks and Office Buildings. In banks or office build- shall not be less than the sum of the loads on the branch ings, the receptacle loads shall be calculated to be the larger circuits supplied, as determined by Part 11 of this article, of(1) or (2): after any applicable demand factors permitted by Part III or (1) The calculated load from 220.14(I) IV or required by Part V have been applied. (2) 11 volt-amperes/m2 or 1 volt-ampere/ft2 FPN: see Examples DI(a) through DIO in Annex D. See 220.18(B) for the maximum load in amperes permitted for (L) Other Outlets. Other outlets not covered in 220.14(A) lighting units operating at less than 100 percent power through (K) shall be calculated based on 180 volt-amperes factor. per outlet. 220.42 General Lighting.The demand factors specified in 220.16 Loads for Additions to Existing Installations. Table 220.42 shall apply to that portion of the total branch- circuit load calculated for general illumination. They shall (A) Dwelling Units. Loads added to an existing dwelling not be applied in determining the number of branch circuits unit(s) shall comply with the following as applicable: (1) Loads for structural additions to an existing dwelling for general illumination. unit or for a previously unwired portion of an existing 220.43 Show-Window and Track Lighting. dwelling unit, either of which exceeds 46.5 m (500 ft`), shall be calculated in accordance with 220.12 and 220.14. (A) Show Windows. For show-window lighting, a load of (2) Loads for new circuits or extended circuits in previ- not less than 660 volt-amperes/linear meter or 200 volt- ously wired dwelling units shall be calculated in accor- amperes/linear foot shall be included for a show window, dance with either 220.12 or 220.14, as applicable. measured horizontally along its base. (B) Other Than Dwelling Units.Loads for new circuits or FPN: See 220.14(G) for branch circuits supplying show extended circuits in other than dwelling units shall be cal- windows. culated in accordance with either 220.12 or 220.14, as ap- plicable. (B) Track Lighting.For track lighting in other than dwell- ing units or guest rooms or guest suites of hotels or motels, 220.18 Maximum Loads. The total load shall not exceed an additional load of 150 volt-amperes shall be included for the rating of the branch circuit, and it shall not exceed the every 600 mm (2 ft) of lighting track or fraction thereof. maximum loads specified in 220.18(A) through (C) under Where multicircuit track is installed, the load shall be con- the conditions specified therein. sidered to be divided equally between the track circuits. (A) Motor-Operated and Combination Loads. Where a 220.44 Receptacle Loads — Other Than Dwelling circuit supplies only motor-operated loads,Article 430 shall Units. Receptacle loads calculated in accordance with apply. Where a circuit supplies only air-conditioning equip- 220.14(H) and (I) shall be permitted to be made subject to ment, refrigerating equipment, or both, Article 440 shall the demand factors given in Table 220.42 or Table 220.44. 70-.60 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 220—BRANCH-CIRCUIT.FEEDER.AND SERVICE CALCULATIONS 220,55 Table 220.42 Lighting Load Demand Factors cent, provided the conductors have an antpacit.v for the load so determined. Portion of Lighting Load to Which 220,52 Small-Appliance and Laundry Loads — Dwell- Type of Applies Demand ing Unit. Occupancy ('Volt-Amperes) Factor(%} (A) Small-Appliance Circuit Load.In each dwelling unit, Dwelling units First 3000 or less at 10() the load shall be calculated at 1500 volt-amperes for each From 3001 to 2-wire small-appliance branch circuit as covered b 120,000 at 35 Y Remainder over 210.11(C)(1). Where the load is subdivided through two or 120,(HM) at 25 more feeders, the calculated load for each shall include not * less than 1500 volt-amperes for each 2-wire small- Hospitals First 50,000 over less at 4() appliance branch circuit. These loads shall be permitted to Remainder over pe 50,000 at 20 be included with the general lighting load and subjected to the demand factors provided in Table 220.42. Hotels and motels, First 20,0W or less at 50 including From 20,001 to Exception: The individual branch circuit permitted by apartment houses 100(X)0 at 210.52{BJ(1), Exception No. 2, slut!! be without provision 40 permitted to be for cooking by Remainder over excluded from the calculation required bti• 220,52. tenants* 100.000 at 30 (B) Laundry Circuit Load. A load of not less than 1500 Warehouses First 12,500 or less at I volt-amperes shall be included for each 2-wire laundry (storage) Remainder over branch circuit installed as covered by 210.11(C)(2). This 12,500 at 50 load shall be permitted to be included with the general All others Total volt-amperes 100 lighting load and subjected to the demand factors provided -The demand Factors of this toile shall not apply to the calculated load in Table 220.42. of feeders or services supplying areas in hU,pil�Lls,hotels,and motels where the entire lighting is likely to be tiled at one time, as in oper- 220.53 Appliance Load — Dwelling Unit(s). It shall be ating rooms, ballrooms, or dining rooms. permissible to apply a demand factor of 75 percent to the nameplate rating load of four or more appliances fastened Table 220.44 Demand Factors For Non-Dwelling Receptacle in place, other than electric ranges, clothes dryers, space- Loads heating equipment, or air-conditioning equipment, that are Portion of Receptacle Load to Which served by the same feeder or service in a one-family, two- Demand Factor Applies family, or multifamily dwelling. (Volt-Amperes) Demand Factor 220.54 Electric Clothes Dryers—Dwelling Unit(s).The Remainder over 10 kV A a[ 5O 0 First k less l load for household electric clothes dryers in a dwelling n a 5 unit(s) shall be either 5000 watts (volt-amperes) or the nameplate rating, whichever is larger, for each dryer 220.50 Motors. Motor loads shall be calculated in accor- served. The use of the demand factors in Table 220.54 shall dance with 430.24, 430.25, and 430.26 and with 440.6 for be permitted. Where two or more single-phase dryers are hermetic refrigerant motor compressors. supplied by a 3-phase, 4-wire feeder or service, the total load shall be calculated on the basis of twice the maximum 220.51 Fixed Electric Space Heating. Fixed electric number connected between any two phases. Kilovolt- space-heating loads shall be calculated at 100 percent of the amperes (kVA) shall be considered equivalent to kilowatts total connected load. However, in no case shall a feeder or (kW) for loads calculated in this section. service load current rating be less than the rating of the largest branch circuit supplied. 220.55 Electric Ranges and Other Cooking Appliances Exception: Where reduced loading of the conductors re- — Dwelling Unit(s). The load for household electric cults front units operating on duty-cycle, intermittent)}t or ranges, wall-mounted ovens, counter-mounted cooking from all units not operating at the same tine, the authority units, and other household cooking appliances individually having jurisdictions nary' grant permission for feeder and rated in excess of 1-314 kW shall be permitted to be calcu- service conductors to have an mnpacitY less than 100 per- lated in accordance with Table 220.55. Kilovolt-amperes 2009 Edition NATIONAL ELECTRICAL CODE 70--61 220.56 ARTICLE 220—BRANCH-CIRCUIT, FEEDER,AND SERVICE CALCULATIONS Table 220.54 Demand Factors for Household Electric 220.60 Noncoincident Loads. Where it is unlikely that Clothes Dryers two or more noncoincident loads will be in use simulta- neously, it shall be permissible to use only the largest Number of Demand Factor load(s)that will be used at one time for calculating the total Dryers M load of a feeder or service. 111 100 5 85 220.61 Feeder or Service Neutral Load. 6 75 7 65 (A) Basic Calculation. The feeder or service neutral load 8 60 shall be the maximum unbalance of the load determined by 9 55 this article. The maximum unbalanced load shall be the 10 50 maximum net calculated load between the neutral conduc- 11 47 for and any one ungrounded conductor. 12-23 47%minus I%for each dryer exceeding 11 Exception: For 3-wire, 2-phase or 5-wire, 2-phase.systems, 24142 35%minus 0.5%ibr each dryer exceeding 23 the maximum unbalanced load shall be the maximum net calculated load between the neutral Conductor and any one 43 and over 25% ungrounded conductor multiplied by 140 percent. (B) Permitted Reductions. A service or feeder supplying (kVA) shall be considered equivalent to kilowatts (kW) for the following loads shall be permitted to have an additional loads calculated under this section. demand factor of 70 percent applied to the amount in Where two or more single-phase ranges are supplied by 220.61(B)(1) or portion of the amount in 220.61(B)(2) de- a 3-phase, 4-wire feeder or service, the total load shall be termined by the basic calculation: calculated on the basis of twice the maximum number con- (1) A feeder or service supplying household electric nected between any two phases. ranges, wall-mounted ovens, counter-mounted cooking FPN No. 1: See Example D5(A) in Annex D. units, and electric dryers, where the maximum unbal- FPN No. 2: See Table 220.56 for commercial cooking anced load has been determined in accordance with equipment. Table 220.55 for ranges and Table 220.54 for dryers FPN No. 3: See the examples in Annex D. (2) That portion of the unbalanced load in excess of 200 amperes where the feeder or service is supplied from a 220.56 Kitchen Equipment — Other Than Dwelling 3-wire do or single-phase ac system; or a 4-wire, Unit(s). It shall be permissible to calculate the load for 3-phase, 3-wire, 2-phase system; or a 5-wire, 2-phase commercial electric cooking equipment, dishwasher system booster heaters, water heaters, and other kitchen equipment (C) Prohibited Reductions.There shall be no reduction of in accordance with Table 220.56. These demand factors the neutral or grounded conductor capacity applied to the shall be applied to all equipment that has either thermo- amount in 220.61(C)(1), or portion of the amount in (C)(2), static control or intermittent use as kitchen equipment. from that determined by the basic calculation: These demand factors shall not apply to space-heating,ven- tilating, or air-conditioning equipment. (1) Any portion of a 3-wire circuit consisting of 2 un- grounded conductors and the neutral Co However, in no case shall the feeder or service calcuconductor of a lated load be less than the sum of the largest two kitchen 4-wire, 3-phase, wye-connected system equipment loads. (2) That portion consisting of nonlinear loads supplied from a 4-wire, wye-connected, 3-phase system Table 220.56 Demand Factors for Kitchen Equipment— FPN No. 1: See Examples D1(a), DI(b), D2(b), D4(a), Other Than Dwelling Unit(s) and D5(a) in Annex D. Number of Units or Demand Factor FPN No. 2: A 3-phase,4-wire,wye-connected power sys- tem used to supply power to nonlinear loads may necessi- tate that the power system design allow for the possibility 1 100 of high harmonic neutral-conductor currents. 2 100 3 90 IV. Optional Feeder and Service Load Calculations 4 80 5 70 220.80 General. Optional feeder and service load calcula- 6 and over 65 tions shall be permitted in accordance with Part 1V. 70-62 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 220—BRANCH-CIRCUIT,FEEDER, AND SERVICE CALCULATIONS 220.80 Table 220.55 Demand Factors and Loads for Household Electric Ranges, Wall-Mounted Ovens, Counter-Mounted Cooking Units,and Other Household Cooking Appliances over 1a kW Rating (Column C to be used in all cases except as otherwise permitted in Note 3.) Demand Factor{%p) (See Notes) Column A Column B Column C Number of (Less than QVI kW through Maximum Demand (kW) (See Appliances 31/2 kW Rating) Sa kW Elating) Notes) (Not over 12 kW Bating) l 80 80 8 2 75 65 11 3 70 55 14 4 66 50 17 5 62 45 20 6 54 43 21 7 S6 40 22 8 53 36 23 9 51 35 24 10 49 34 25 11 47 32 26 12 45 32 27 13 43 32 28 14 41 32 29 15 40 32 30 16 39 28 31 17 38 28 32 18 37 28 33 19 36 28 34 20 35 28 35 21 34 26 36 22 33 26 37 23 32 26 38 24 31 26 39 25 30 26 40 26-30 30 24 15 kW+ 1 kW for each range 31-10 30 22 41-50 30 20 25 kW+ '/4 kW for each range 51-60 30 18 61 and over 30 16 Notes: 1, Over 12 kW through 27 kW ranges all of same rating. For ranges individually rated more than 12 kW but not more than 27 kW, the maximum demand in Column C shall be increased 5 percent for each additional kilowatt of rating or major fraction thereof by which the rating of individual ranges exceeds 12 kW. 2. Over V/a kW through 27 kW ranges of unequal ratings. For ranges individually rated more than 8'/4 kW and of different ratings, but none exceeding 27 kW,an average value of rating shall be calculated by adding together the ratings of all ranges to obtain the total connected load fusing 12 kW for any range rated lesc than 12 kW)and dividing by the total number of ranges.Then the maximum demand in Column C shall be increased 5 percent for each kilowatt or major fraction thereof by which this average value exceeds 12 kW. 3.Over 1'/4 kW through 8'/4 kW.In lieu of the method provided in Column C,it shall be permissible to add the nameplate ratings of all household cooking appliances rated more than 1'14 kW but not more than &'/4 kW and multiply the sum by the demand factors specilied in Column A or Column B for the given number of appliances. Where the rating of cooking appliances falls under both Column A and Column B, the demand factors for each column shall be applied to the appliances for that column, and the results added together. 4. Branch-Circuit Load. It shall be permissible to calculate the branch-circuit load for one range in accordance with Table 220.55.The branch- circuit load for one wall-mounted oven or one counter-mounted cooking unit shall be the nameplate rating of the appliance.The branch-circuit load for a counter-mounted cooking unit and not more than two wall-mounted ovens,all supplied from a single branch circuit and located in the same room, shall he calculated by adding the nameplate rating of the individual appliances and treating this total as equivalent to one range. 5.This table shall also apply to household cooking appliances rated over 1'/4 kW and used in instructional programs. 2008 Edition NATIONAL,ELECTRICAL CODE 70--63 220.82 ARTICLE 220—BRANCH-CIRCUIT.FEEDER,AND SERV[CE CALCULATIONS 220.82 Dwelling Unit. (5) 40 percent of the nameplate rating(s) of electric space {A} Feeder and Service Load. This section applies to a heating if four or more separately controlled units. dwelling unit having the total connected load served by a (6) 100 percent of the nameplate ratings of electric thermal single 1201240-volt or 208Y/120-volt set of 3-wire service storage and other heating systems where the usual load or feeder conductors with an ampacity of 100 or greater. It is expected to be continuous at the full nameplate shall be permissible to calculate the feeder and service value. Systems qualifying under this selection shall not loads in accordance with this section instead of the method be calculated under any other selection in 220.82(C). specified in Part III of this article.The calculated load shall 220.83 Existing Dwelling Unit.This section shall be per- be the result of adding the loads from 220.82(B) and (C). mitted to be used to determine if the existing service or Feeder and service-entrance conductors whose calculated feeder is of sufficient capacity to serve additional loads. load is determined by this optional calculation shall he per- Where the dwelling unit is served by a 1201240-volt or mitted to have the neutral load determined by 220.61. 208Y1120-volt, 3-wire service, it shall be permissible to cal- (B) General Loads. The general calculated load shall be culate the total load in accordance with 220.83(A) or(B). not less than 100 percent of the first 10 kVA plus 40 percent of the remainder of the following loads: (A) Where Additional Air-Conditioning Equipment or Electric Space-Heating Equipment Is Not to Be In- (1) 33 volt-ampereslm` or 3 volt-amperes/ft� for general stalled. The following formula shall be used for existing lighting and general-use receptacles. The floor area for and additional new loads. each floor shall be calculated from the outside dimen- sions of the dwelling unit. The calculated floor area Load [kVA) Percent of Load shall not include open porches, garages, or unused or first 8 kVA of load at 100 unfinished spaces not adaptable for future use. Remainder of load at 40 (2) 1500 volt-amperes for each 2-wire, 20-ampere small- appliance branch circuit and each laundry branch cir- Load calculations shall include the following: cuit covered in 210.11(C)(1) and (C)(2). {3) The nameplate rating of the following: (1) General lighting and general-use receptacles at 33 volt- (3) or 3 volt-ampereslft as determined by a. All appliances that are fastened in place, permanently 220.12 connected, or located to be on a specific circuit b. Ranges, wall-mounted ovens, counter-mounted (2) 1500 volt-amperes for each 2-wire, 20-ampere small- cooking units appliance branch circuit and each laundry branch cir- c. Clothes dryers that are not connected to the laundry cuit covered in 210.11(C)(1) and (C)(2) branch circuit specified in item (2) (3) The nameplate rating of the following: d. Water heaters a. All appliances that are fastened in place, perma- (4) The nameplate ampere or kVA rating of all perma- nently connected, or located to be on a specific cir- nently connected motors not included in item (3). cuit (C) Heating and Air-Conditioning Load. The largest of b. Ranges, wall-mounted ovens, counter-mounted cook- the following six selections (load in kVA) shall be in- ing units eluded: c. Clothes dryers that are not connected to the laundry (1) 100 percent of the nameplate rating(s) of the air condi- branch circuit specified in item (2) tioning and cooling. d. Water heaters (2) 100 percent of the nameplate rating(s)of the heat pump (g) Where Additional Air-Conditioning Equipment or when the heat pump is used without any supplemental Electric Space-Heating Equipment Is to Be Installed. electric heating. The following formula shall be used for existing and addi- (3) 100 percent of the nameplate rating(s)of the heat pump tional new loads. The larger connected load of air- compressor and 65 percent of the supplemental electric conditioning or space-heating, but not both, shall be used. heating for central electric space-heating systems. If the Load Percent of Load heat pump compressor is prevented from operating at the same time as the supplementary heat, it does not Air-conditioning equipment 100 need to be added to the supplementary heat for the total Central electric space heating 100 central space heating load. Less than four separately 100 controlled space-heating units (4) 65 percent of the nameplate rating(s) of electric space First 8 kVA of all other loads 100 heating if less than four separately controlled units. Remainder of all other loads 40 70-64 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 220—BRANCH-CIRCUIT, FEEDER.AND SERVICE CALCULATIONS 220.86 Other loads shall include the following: Table 220.84 Optional Calculations— Demand Factors for (1) General lighting and general-use receptacles at 33 volt- Three or More Multifamily Dwelling Units amperes/M2 or 3 volt-amperes/ft2 as determined by - 220.12 Number of Demand Factor (2) 1500 volt-amperes for each 2-wire, 20-ampere small- Dwelling Units (%t) appliance branch circuit and each laundry branch cir- 3-5 45 cuit covered in 210.1I(C)(1) and (C)(2) 6-7 44 (3) The nameplate rating of the following: 8-10 43 a. All appliances that are fastened in place, perma- 11 42 nently connected, or located to be on a specific cir- 12-13 41 cuit 14-15 40 16-17 39 b. Ranges, wall-mounted ovens, counter-mounted 18-20 38 cooking units c, Clothes dryers that are not connected to the.laundry 21 37 branch circuit specified in (2) 2223 36 d. Water heaters 24--25 35 26-27 34 220.84 Multifamily Dwelling. 28-30 33 (A) Feeder or Service Load. It shall be permissible to 31 32 calculate the load of a feeder or service that supplies three 32-33 31 34-36 30 or more dwelling units of a multifamily dwelling in accor- 37-38 29 dance with Table 220.84 instead of Part III of this article if 39-42 28 all the following conditions are met: (1) No dwelling unit is supplied by more than one feeder. 43-45 27 46--50 26 (2) Each dwelling unit is equipped with electric cooking 51-55 25 equipment. 56-61 24 Exception: When the calculated load for multifamily divell- 62 and over 23 ings without electric cooking in Part III of this article ex- ceeds that calculated under Part X far the identical load b. Ranges, wall-mounted ovens, counter-mounted plus electric cooking (bused on kW per unit), the lesser of cooking units the two loads .shall be permitted to be used. c. Clothes dryers that are not connected to the laundry (3) Each dwelling unit is equipped with either electric branch circuit specified in item (2) d. Water heaters space heating or air conditioning, or both. Feeders and service conductors whose calculated load is determined (4} The nameplate ampere or kVA rating of all perma- by this optional calculation shall be permitted to have nently connected motors not included in item (3) the neutral load determined by 220.61. (5) The larger of the air-conditioning load or the fixed elec- (B) House Loads. House loads shall be calculated in ac- tric space-heating load cordance with Part III of this article and shall be in addition 220.85 Two Dwelling Units. Where two dwelling units to the dwelling unit loads calculated in accordance with are supplied by a single feeder Arid the calculated load Table 220.84. under Part III of this article exceeds that for three identical (C) Connected Loads. The calculated load to which the units calculated under 220.84, the lesser of the two loads demand factors of Table 220.84 apply shall include the shall be permitted to be used. following: (1) 33 volt-ampereslm2 or 3 volt-ampereslft2 for general 220.86 Schools. The calculation of a feeder or service lighting and general-use receptacles load for schools shall be permitted in accordance with (2) 1500 volt-amperes for each 2-wire, 20-ampere small- Table 220.86 in lieu of Part III of this article where equipped with electric space heating, air conditioning, or appliance branch circuit and each laundry branch cir- both. The connected load to which the demand factors of cult covered in 210.11(C)(1) and (C}(2} Table 220.86 apply shall include all of the interior and (3) The nameplate rating of the following: exterior lighting, power, water heating, cooking, other a. All appliances that are fastened in place, permanently loads, and the larger of the air-conditioning load or space- connected, or located to be on a specific circuit heating load within the building or structure. 2008 Edition NATIONAL ELECTRICAL CODE 70-65 220,87 ARTICLE 220—BRANCH-CIRCUIT,FEEDER,AND SERVICE CALCULATIONS Feeders and service conductors whose calculated load (2) The maximum demand at 125 percent plus the new is determined by this optional calculation shall be permitted load does not exceed the ampacity of the feeder or to have the neutral load determined by 220.61. Where the rating of the service. building or structure load is calculated by this optional (3) The feeder has overcurrent protection in accordance method, feeders within the building or structure shall have with 240.4, and the service has overload protection in ampacity as permitted in Part III of this article; however, accordance with 230.90. the ampacity of an individual feeder shall not be required to be larger than the ampacity for the entire building. 220.88 New Restaurants. Calculation of a service or This section shall not apply to portable classroom feeder load, where the feeder serves the total load, for a buildings. new restaurant shall be permitted in accordance with Table 220.88 in lieu of Part III of this article. Table 220.86 Optional Method —Demand Factors for The overload protection of the service conductors shall Feeders and Service Conductors for Schools be in accordance with 230.90 and 240.4. Demand Feeder conductors shall not be required to be of greater Factor ampacity than the service conductors. Connected Load (Percent) Service or feeder conductors whose calculated load is determined by this optional calculation shall be permitted First 33 VA/m2 (3 VAlft2) at 100 to have the neutral load determined by 220.61. Plus, Over 33 to 220 VA/m2 (3 to 20 VAlft2) at 75 Plus, V. Farm Load Calculations Remainder over 220 (20 VA/ft2) at 25 VA/M2 220.100 General. Farm loads shall be calculated in accor- dance with Part V. 220.87 Determining Existing Loads.The calculation of a 220.102 Farm Loads — Buildings and Other Loads. feeder or service load for existing installations shall be permitted to use actual maximum demand to determine the (A) Dwelling Unit. The feeder or service load of a farm existing load under all of the following conditions: dwelling unit shall be calculated in accordance with the (1) The maximum demand data is available for a 1-year provisions for dwellings in Part III or IV of this article. period. Where the dwelling has electric heat and the farm has elec- tric grain-drying systems, Part IV of this article shall not be Exception: If the maximum demand data for a 1-year pe- used to calculate the dwelling load where the dwelling and riod is not available, the calculated load shall be permitted farm loads are supplied by a common service. to be based on the maximum demand(measure of average power demand over a 15-minute period) continuously re- (B) Other Than Dwelling Unit.Where a feeder or service corded over a minimum 30-day period using a recording supplies a farm building or other load having two or more ammeter or power meter connected to the highest loaded separate branch circuits, the load for feeders, service con- phase of the feeder or service, based on the initial loading ductors,and service equipment shall be calculated in accor- at the start of the recording. The retarding shall reflect the dance with demand factors not less than indicated in Table maximum demand of the feeder or service by being taken 220.102. when the building or space is occupied and shall include by measurement or calculation the larger of the heating or 220.103 Farm Loads—Total.Where supplied by a com- cooling equipment load, and other loads that may be peri- mon service, the total load of the farm for service conduc- odic in nature due to seasonal or similar conditions. tors and service equipment shall be calculated in accor- Table 220.88 Optional Method—Permitted Load Calculations for Service and Feeder Conductors for New Restaurants Total Connected All Electric Restaurant Not All Electric Restaurant Load (kVA) Calculated Loads (kVA) Calculated Loads (kVA) 0-200 80% 10010 201-325 10% (amount over 200) + 160.0 50% (amount over 200)+200.0 326-800 50% (amount over 325) + 172.5 45% (amount over 325)+262.5 Over 800 50% (amount over 800) +410.0 20% (amount over 800) +476.3 Note:Add all electrical loads, including both heating and cooling loads, to calculate the total connected load. Select the one demand factor that applies from the table, then multiply the total connected load by this single demand factor. 70-66 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLF 225—OUTSIDE BRANCH CIRCUITS AND FEFDFRS 225.4 Table 220.102 Method For Calculating Farm Loads For Table 225.2 Other Articles Other Than Dwelling Unit Ampere Load of Demand Factor Equipment/Conductors Article 240 Volts Maximum Branch circuits 210 Class 1, Class 2, and Class 3 725 Loads expected to operate 100 remote-control, signaling, and simultaneously, but not less than power-limited circuits 125 percent full-load current or the Communications circuits 800 largest motor and not less than the Community antenna television and radio 820 first 60 amperes of load distribution systems Next 60 amperes of all other loads 50 Conductors for general wiring 310 Remainder of other loads 25 Electrically driven or controlled 675 irrigation machines Electric signs and outline lighting 600 dance with the farm dwelling unit load and demand factors Feeders 215 specified in Table 220.103, Where there is equipment in Fire alarm systems 760 two or more farm equipment buildings or for loads having Fixed outdoor electric deicing and 426 the same function, such loads shall be calculated in accor- snow-melting equipment dance with Table 220.102 and shall be permitted to be Floating buildings 553 Grounding 250 combined as a single load in Table 220.103 for calculating Hazardous (classified) locations 500 the total load. Hazardous (classified) locations 510 specific Table 220.103 Method for Calculating Total Farm Load Marinas and boatyards 555 Messenger-supported wiring 396 Individual Loads Calculated in Demand Factor Mobile homes, manufactured homes, 550 Accordance with Table 220.102 (qo) and mobile home parks Open wiring on insulators 398 Largest load 100 Over 600 volts, general 490 Second largest load 75 Overcurrent protection 240 Third largest load 65 Radio and television equipment S10 Remaining loads 50 Services 230 Solar photovoltaic systems 690 Note:To this total load,add the load of the farm dwelling unit calcu- Swimming pools, fountains, and similar 680 lated in accordance with Pan HI or IV of this article. Where the installations dwelling has electric heat and the farm has electric grain-drying, sys- Use and identification of grounded 200 tems,Part IV of this article shall not be used to calmlatc the dwelling conductors load. I. General 225.3 Calculation of Loads 600 Volts, Nominal, or Less. (A) Branch Circuits. The load on outdoor branch circuits ARTICLE 225 shall be as determined by 220.10. Outside Branch Circuits and Feeders (B) Feeders. The load on outdoor feeders shall be as de- termined by Part III of Article 220. 225.1 Scope. This article covers requirements for outside branch circuits and feeders run on or between buildings, 225.4 Conductor Covering.Where within 3.0 in(10 ft)of structures, or poles on the premises; and electrical equip- any building or structure other than supporting poles or ment and wiring for the supply of utilization equipment that towers, open individual {aerial) overhead conductors shall is located on or attached to the outside of buildings, struc- tures, or poles. except Type MI cable, shall be of the rubber-covered type or thermoplastic type and, in wet locations, shall comply FPN: For additional information on wiring over 600 volts, with 310.8. Conductors for festoon lighting shall be of the see ANSI C2-2007, National Electrical Safety Code. rubber-covered or thermoplastic type. 225.2 Other Articles. Application of other articles, includ- Exception: Equipment grounding conductors and ing additional requirements to specific cases of equipment grounded circuit conductors shall be permitted to be bare and conductors, is shown in Table 225.2. or covered as specifically permitted elsewhere in this Code. 2008 Edition NATIONAL ELEC-rRICAL CODE. 70-67 225.5 ARTICLE 225—OUTSIDE BRANCH CIRCUITS AND FEEDERS 225.5 Size of Conductors 600 Volts, Nominal, or Less. insulators, as multiconductor cable, as Type MC cable, as The ampacity of outdoor branch-circuit and feeder conduc- Type OF cable, as Type MI cable, as messenger-supported tors shall be in accordance with 310.15 based on loads as wiring, in rigid metal conduit, in intermediate metal con- determined under 220.10 and Part IIi of Article 220. duit, in rigid nonmetallic conduit, in cable trays, as cable- bus, in wireways, in auxiliary gutters, in electrical metallic 225.6 Conductor Size and Support, tubing, in flexible metal conduit, in liquidtight flexible metal conduit, in liquidtight flexible nonmetallic conduit, {A) Overhead Spans. Open individual conductors shall and in busways. Circuits of over 600 volts, nominal, shall not be smaller than the following: be installed as provided in 300.37. (1) For 600 volts, nominal, or less, 10 AWG copper or 8 AWG aluminum for spans up to 15 m (50 ft) in 225.11 Circuit Exits and Entrances. Where outside length, and 8 AWG copper or 6 AWG aluminum for a branch and feeder circuits leave or enter a building, the longer span unless supported by a messenger wire requirements of 230.52 and 230.54 shall apply. (2) For over 600 volts, nominal, 6 AWG copper or 4 AWG aluminum where open individual conductors, and 225.12 Open-Conductor Supports. Open conductors 8 AWG copper or 6 AWG aluminum where in cable shall be supported on glass or porcelain knobs, racks, (B) Festoon Lighting. Overhead conductors for festoon brackets, or strain insulators. lighting shall not be smaller than 12 AWG unless the con- ductors are supported by messenger wires. In all spans ex- ceeding 12 m (40 ft), the conductors shall be supported by (A) 600 Volts,Nominal,or Less.Conductors of 600 volts, messenger wire. The messenger wire shall be supported by nominal, or less, shall comply with the spacings provided strain insulators. Conductors or messenger wires shall not in Table 230.51(C). be attached to any fire escape, downspout, or plumbing equipment. (B) Over 600 Volts, Nominal. Conductors of over 600 volts, nominal, shall comply with the spacings provided in 225.7 Lighting Equipment Installed Outdoors. 110,36 and 490.24. (A) General. For the supply of lighting equipment in- (C) Separation from Other Circuits. Open conductors stalled outdoors, the branch circuits shall comply with Ar- ticle 210 and 225.7(B) through (D), shall be separated from open conductors of other circuits or systems by not less than 100 mm (4 in.). (B) Common Neutral. The ampacity of the neutral con- ductor shall not be less than the maximum net computed (U) Conductors on Poles.Conductors on poles shall have load current between the neutral conductor and all un- a separation of not less than 300 mm (1 ft) where not grounded conductors connected to any one phase of the placed on racks or brackets.Conductors supported on pales circuit. shall provide a horizontal climbing space not less than the following: (C) 277 Volts to Ground. Circuits exceeding 120 volts, (1) Power conductors below communications conductors nominal, between conductors and not exceeding 277 volts, —750 mm (30 in.) nominal, to ground shall be permitted to supply luminaires (2) Power conductors alone or above communications con- for illumination of outdoor areas of industrial establish- ductors: ments, office buildings, schools, stores, and other commer- a. 300 volts or less — 600 mm (24 in.) cial or public buildings where the luminaires are not less b. Over 300 volts -- 750 mm (30 in.) than 900 mm (3 ft) from windows, platforms, fire escapes, and the like. (3) Communications conductors below power conductors — same as power conductors (D) 600 Volts Between Conductors. Circuits exceeding (4) Communications conductors alone — no requirement 277 volts, nominal, to ground and not exceeding 600 volts, nominal, between conductors shall be permitted to supply 225.15 Supports over Buildings.Supports over a building the auxiliary equipment of electric-discharge lamps in ac- shall be in accordance with 230.29. cordance with 210.6(D)(1). 225.16 Attachment to Buildings. 225.10 Wiring on Buildings. The installation of outside wiring on surfaces of buildings shall be permitted for cir- (A) Point of Attachment. The point of attachment to a cuits of not over 600 volts, nominal, as open wiring on building shall be in accordance with 230.26. 70-68 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 225—OUTSIDE BRANCH CIRCUITS AND FEEDERS 225.20 (B) Means of Attachment. The means of attachment to a the overhanging portion of'the r000f to not less than 450 non building shall be in accordance with 230.27. (18 in.) shall be permitted if(1) not more than 1.8 nz (6 ft) of the conductors, 1.2 in (4 ft) horizontally, pass above the 225.17 Masts as Supports. Where a mast is used for the roof overhang and(2) they are terminated at a through-the- support of final spans of feeders or branch circuits, it shall roof racetivay or approved support. be of adequate strength or be supported by braces or guys Exception No. 4: The requirement for maintaining the ver- to withstand safely the strain imposed by the overhead tical clearance 900 min (3 ft)from the edge of the roof shall drop. Where raceway-type masts are used, all raceway fit- not apply to the final conductor span where the conductors tings shall be identified for use with masts. Only the feeder are attached to the side of a building. or branch-circuit conductors specified within this section shall be permitted to be attached to the feeder and/or (B) From Nonbuilding or Northridge Structures. From branch-circuit mast, signs, chimneys, radio and television antennas, tanks, and other nonbuilding or nonbridge structures, clearances — 225.18 Clearance for Overhead Conductors and vertical, diagonal, and horizontal — shall not be less than Cables. Overhead spans of open conductors and open mul- 900 mm (3 ft). ticonductor cables of not over 600 volts, nominal, shall have a clearance of not less than the following: (C) Horizontal Clearances. Clearances shall not be less (1) 3.0 m (10 ft) — above finished grade, sidewalks, or than 900 mm (3 ft). from any platform or projection from which they might be reached where the voltage does not exceed 150 volts (D) Final Spans. Final spans of feeders or branch circuits to ground and accessible to pedestrians only shall comply with 225.19(D)(1), (D)(2), and (D)(3). (2) 3.7 m (12 ft) — over residential property and drive- (1) Clearance from Windows. Final spans to the building ways, and those commercial areas not subject to truck they supply, or from which they are fed, shall be permitted traffic where the voltage does not exceed 300 volts to to be attached to the building,but they shall be kept not less ground than 900 mm (3 ft) from windows that are designed to be (3) 4.5 m (15 ft) — for those areas listed in the 3.7-m opened, and from doors, porches, balconies, ladders, stairs, (I2-ft) classification where the voltage exceeds 300 fire escapes, or similar locations. volts to ground (4) 5.5 m (18 ft) —over public streets, alleys, roads, park- Exception: Conductors ran above the top level of a wir- ing areas subject to truck traffic, driveways on other dox' shall be permitted to he less than the 900-rnm (3-ft) than residential property, and other land traversed by requirement, vehicles, such as cultivated, grazing, forest, and (2) Vertical Clearance. The vertical clearance of final orchard spans above,or within 900 mm(3 ft) measured horizontally of, platforms, projections, or surfaces from which they 225.19 Clearances from Buildings for Conductors of might be reached shall be maintained in accordance with Not over 600 Volts, Nominal. 225.18. (A) Above Roofs. Overhead spans of open conductors and (3) Building Openings. The overhead branch-circuit and open multiconductor cables shall have a vertical clearance feeder conductors shall not be installed beneath openings of not less than 2.5 m (8 ft) above the roof surface. The through which materials may be moved, such as openings vertical clearance above the roof level shall be maintained in farm and commercial buildings,and shall not be installed for a distance not less than 900 mm (3 ft) in all directions where they obstruct entrance to these buildings' openings. from the edge of the roof. Exception No. 1: The area above a roof surface subject to (E) Zone for Fire Ladders. Where buildings exceed three pedestrian or vehicular traffic shall have a vertical clear- stories or 15 m (50 ft) in height, overhead lines shall be anc•e from the roof surface in accordance with the clear- arranged, where practicable, so that a clear space (or zone) ance requirements of 225.18. at least 1.8 m (6 ft) wide will be left either adjacent to the buildings or beginning not over 2.5 m (8 ft) from them to Exception No. 2: Where the voltage between conductors facilitate the raising of ladders when necessary for fire does not exceed 300, and the roof has a slope of 100 mm in fighting. 300 nun (4 in, in 12 in.)or greater, a reduction in clearance to 900 rnm (3 ft) shall be pennittecl' 225.20 Mechanical Protection of Conductors. Mechani- Exception No. 3: Where the voltage between conductors cal protection of conductors on buildings, structures, or does not exceed 300, a reduction in clearance above only poles shall be as provided for services in 230.50. 2(X)8 Edition NATIONAL ELECTRICAL CODE 70-69 225,21 ARTICLE 225—OUTSIDE BRANCH CIRCUITS AND FEEDERS 225.21 Multiconductor Cables on Exterior Surfaces of (2) A single building or other structure sufficiently large to Buildings. Supports for multiconductor cables on exterior make two or more supplies necessary surfaces of buildings shall be as provided in 230.51.. (C) Capacity Requirements.Additional feeders or branch 225.22 Raceways on Exterior Surfaces of Buildings or circuits shall be permitted where the capacity requirements Other Structures. Raceways on exteriors of buildings or are in excess of 2000 amperes at a supply voltage of 600 other structures shall be arranged to drain and shall be volts or less. raintight in wet locations. • (D) Different Characteristics. Additional feeders or 225.24 Outdoor Lampholders. Where outdoor lamphold- branch circuits shall be permitted for different voltages, ers are attached as pendants, the connections to the circuit frequencies, or phases or for different uses, such as control wires shall be staggered. Where such lampholders have of outside lighting from multiple locations. terminals of a type that puncture the insulation and make contact with the conductors, they shall be attached only to (E) Documented Switching Procedures. Additional feed- conductors of the stranded type. ers or branch circuits shall be permitted to supply instaIla- tions under single management where documented safe 225.25 Location of Outdoor Lamps. Locations of lamps switching procedures are established and maintained for for outdoor lighting shall be below all energized conduc- disconnection. tors, transformers, or other electric utilization equipment, unless either of the following apply: 225.31 Disconnecting Means. Means shall be provided (1) Clearances or other safeguards are provided for for disconnecting all ungrounded conductors that supply or relamping operations. pass through the building or structure. (2) Equipment is controlled by a disconnecting means that can be locked in the open position. 225.32 Location. The disconnecting means shall be in- stalled either inside or outside of the building or structure 225.26 Vegetation as Support. Vegetation such as trees served or where the conductors pass through the building or shall not be used for support of overhead conductor spans. structure. The disconnecting means shall be at a readily accessible location nearest the point of entrance of the con- II. More Than One Building or Other Structure ductors. For the purposes of this section, the requirements in 230.6 shall be utilized. 225.30 Number of Supplies. Where more than one build- ing or other structure is on the same property and under Exception No. 1: For installations under single manage- single management,each additional building or other struc- ment, where documented safe switching procedures are es- ture that is served by a branch circuit or feeder on the load tablished and maintained far disconnection, and where the side of the service disconnecting means shall be supplied installation is monitored by qualified individuals, the dis- by only one feeder or branch circuit unless permitted in connecting means shall be permitted to be located else- 225.30(A) through (E). For the purpose of this section, a where on the premises. multiwire branch circuit shall be considered a single circuit. Exception No. 2: For buildings or other structures quali- fying under the provisions of Article 685, the disconnecting (A) Special Conditions. Additional feeders or branch cir- means shall be permitted to be located elsewhere on the cults shall be permitted to supply the following: premises. (1) Fire pumps (2) Emergency systems Exception No. 3: For towers or poles used as lighting standards, the disconnecting means shall be permitted to be (3) Legally required standby systems located elsewhere on the premises. (4) Optional standby systems Exception No. 4: For poles or similar structures used only (5) Parallel power production systems for support of signs installed in accordance with Article (6) Systems designed for connection to multiple sources of 600, the disconnecting means shall be permitted to be lo- supply for the purpose of enhanced reliability cated elsewhere on the premises. (B) Special Occupancies. By special permission, addi- 225.33 Maximum Number of Disconnects. tional feeders or branch circuits shall be permitted for ei- ther of the following: (A) General. The disconnecting means for each supply (1) Multiple-occupancy buildings where there is no permitted by 225.30 shall consist of not more than six space available for supply equipment accessible to switches or six circuit breakers mounted in a single enclo- all occupants sure,in a group of separate enclosures,or in or on a switch- 70-70 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 225—OUTSIDE BRANCH CIRCUITS AND FEEDERS 225.39 board. There shall be no more than six disconnects per 225.37 Identification. Where a building or structure has supply grouped in any one location. any combination of feeders, branch circuits, or services passing through it or supplying it, a permanent plaque or Exception: For the purposes of This section, disconnecting passing shall be installed at each feeder and branch-circuit means used solely for the control circuit of flue grnmid fault disconnect location denoting all other services, feeders, or protection system, or the control circuit of the power' branch circuits supplying that building or structure or pass- operated supply disconnecting means, installed as part of ing through that building or structure and the area served by the listed equipment, shall not be considered a supph' dis each. connecting means. Exception No. 1: A plaque or director' shall not be re- (B) Single-Pole Units. Two or three single-pole switches quired for large-capacity multibuilding industrial installa- or breakers capable of individual operation shall be permit- tions under single management, where it is ensured that ted on multiwire circuits, one pole for each ungrounded disconnection can be accomplished by establishing and conductor, as one multipole disconnect, provided they are maintaining safe switching procedures, equipped with identified handle ties or a master handle to Exception No. 2: This identification shall not be required disconnect all ungrounded conductors with no more than for branch circuits installed from a divelling unit to a sec- six operations of the hand. and buildings or structure. 225.34 Grouping of Disconnects. 225.38 Disconnect Construction. Disconnecting means (A) General. The two to six disconnects as permitted in shall meet the requirements of 225.38(A) through (D). 225.33 shall be grouped. Each disconnect shall be marked Exception: For garages and outbuildings on residential to indicate the load served. property, snap switches or sets of 3-wap or 4-watt snap switches shall be permitted as the disconnecting means. Exception: Otte of the two to six disconnecting means per- mitted in 225.33, where used only for a water pump also (A) Manually or Power Operable. The disconnecting intended to provide fire protection, shall be permitted to be means shall consist of either(l) a manually operable switch located remote from the other disconnecting means. or a circuit breaker equipped with a handle or other suitable (B) Additional Disconnecting Means. The one or more operating means or (2) a power-operable switch or circuit breaker, provided the switch or circuit breaker can be additional disconnecting means for fire pumps or for emer- enc legally required standby or optional standby system opened by hand in the event of a power failure. g Y, g' Y q Y P Y Y permitted by 225.30 shall be installed sufficiently remote (B) Simultaneous Opening of Poles. Each building or from the one to six disconnecting means for normal supply Structure disconnecting means shall simultaneously discon- to minimize the possibility of simultaneous interruption of neat all ungrounded supply conductors that it controls from supply. the building or structure wiring system. 225.35 Access to Occupants. In a multiple-occupancy (C) Disconnection of Grounded Conductor. Where the building, each occupant shall have access to the occupant's building or structure disconnecting means does not discon- supply disconnecting means, neat the grounded conductor from the grounded conductors in the building or structure wiring, other means shall be Exception: In a multiple-occupancy building where elec- provided for this purpose at the location of disconnecting tric supphy and electrical maintenance are provided by the means.A terminal or bus to which all grounded conductors building management and where these are under continu- can be attached by means of pressure connectors shall be ous building management supervision, the supply discon- permitted for this purpose. netting means supplying more than one occupancy shall be In a multisection switchboard, disconnects for the permitted to be accessible to authorized management per- grounded conductor shall be permitted to be in any section sonnel vnh•. of the switchboard, provided any such switchboard section is marked. 225.36 Suitable for Service Equipment. The disconnect- ing means specified in 225.31 shall be suitable for use as (D) Indicating, The building or structure disconnecting service equipment. means shall plainly indicate whether it is in the open or closed position. Exception: For garages and outbuildings on residential property. a snap switch or a set of 3-way or 4-wav snap 225.39 Rating of Disconnect.The feeder or branch-circuit switches shall be permitted as the disconnecting means. disconnecting means shall have a rating of not less than the 2008 Edition NATIONAL ELECTRICAL CODE 70-71 225.40 ARTICLE 225—OUTSIDE BRANCH CIRCUITS AND FEEDERS calculated load to be supplied, determined in accordance 225.52 Location. A building or structure disconnecting with Parts I and II of Article 220 for branch circuits,Part III means shall be located in accordance with 225.32, or it or IV of Article 220 for feeders,or Part V of Article 220 for shall be electrically operated by a similarly located remote- farm loads. Where the branch circuit or feeder disconnect- control device. ing means consists of more than one Switch or circuit breaker, as permitted by 225.33, combining the ratings of 225.53 Type. Each building or structure disconnect shall all the switches or circuit breakers for determining the rat- simultaneously disconnect all ungrounded supply conduc- ing of the disconnecting means shall be permitted. In no tors it controls and shall have a fault-closing rating not less case shall the rating be lower than specified in 225.39(A), than the maximum available short-circuit current available (B), (C), or (D). at its supply terminals. Where fused switches or separately mounted fuses are in- (A) One-Circuit Installation. For installations to supply stalled, the fuse characteristics shall be permitted to contribute only limited loads of a single branch circuit, the branch to the fault closing rating of the disconnecting means. circuit disconnecting means shall have a rating of not less than 15 amperes. 225.60 Clearances over Roadways, Walkways, Rail, (B) Two-Circuit Installations. For installations consisting Water, and Open Land. of not more than two 2-wire branch circuits, the feeder or (A) 22 kV, Nominal, to Ground or Less. The clearances branch-circuit disconnecting means shall have a rating of over roadways, walkways, rail, water, and open land for con- not less than 30 amperes. ductors and live parts up to 22 kV,nominal, to ground or less (C) One-Family Dwelling.For a one-family dwelling, the shall be not less than the values shown in Table 225.60. feeder disconnecting means shall have a rating of not less Table 225.60 Clearances over Roadways,Walkways,Rail, than 100 amperes, 3-wire. Water, and Open Land (D) All Others. For all other installations, the feeder or Clearance branch-circuit disconnecting means shall have a rating of not less than 60 amperes. Location m ft Open land subject to vehicles, 5.6 18.5 225.40 Access to Overcurrent Protective Devices.Where cultivation, or grazing a feeder overcurrent device is not readily accessible, Roadways, driveways, parking 5.6 18.5 branch-circuit overcurrent devices shall be installed on the lots, and alleys load side, shall be mounted in a readily accessible location, Walkways 4.1 13.5 and shall be of a lower ampere rating than the feeder over- Rails 8.1 26.5 Spaces and ways for pedestrians 4.4 14.5 current device. and restricted traffic Water areas not suitable for 5.2 17.0 III. Over 600 Volts boating 225.50 Sizing of Conductors. The sizing of conductors (B) Over 22 kV Nominal to Ground. Clearances for the over 600 volts shall be in accordance with 210.19(B) for categories shown in Table 225.60 shall be increased by branch circuits and 215.2(B) for feeders. 10 mm (0.4 in.) per kV above 22,000 volts. 225.51 Isolating Switches. Where oil switches or air, oil, (C) Special Cases. For special cases, such as where cross- vacuum, or sulfur hexafluoride circuit breakers constitute a ings will be made over lakes, rivers, or areas using large building disconnecting means, an isolating switch with vis- vehicles such as mining operations, specific designs shall ible break contacts and meeting the requirements of be engineered considering the special circumstances and 230.204(B), (C), and (D) shall be installed on the supply side shall be approved by the authority having jurisdiction. of the disconnecting means and all associated equipment. FPN: For additional information, see ANSI C2-2007, No- Exception: The isolating switch shall not be required tional Electrical Safety Code. where the disconnecting means is mounted on removable 225.61 Clearances over Buildings and Other Structures. truck panels or metal-enclosed switehgear units that cannot be opened unless the circuit is disconnected and that, when (A) 22 kV Nominal to Ground or Less. The clearances removed from the normal operating position, automatically over buildings and other structures for conductors and live disconnect the circuit breaker or switch from all energized parts up to 22 kV, nominal, to ground or less shall be not parts. less than the values shown in Table 225.61. 70-72 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 230—SERVICES 230.2 Table 225.61 Clearances over Buildings and Other General Part I Structures Overhead Service-Drop Conductors Part Il Underground Service-Lateral Conductors Part III Service-Entrance Conductors Part IV Clearance from Horizontal Vertical Service Equipment General Part V Conductors or Live Service Equipment—Disconnecting Means Part VI Parts from: m ft m ft Service Equipment—Overcurrent Protection Part VII Services Exceeding 600 Volts,Nominal Part Vlll Building walls, 2.3 7.5 -- — Source projections, and windows Overhead Underground Balconies, catwalks, and 2.3 7.5 4.1 13.5 Last pole Street main similar areas accessible to people Part II Service drop Service lateral Part III Over or under roofs or — — 3.8 12.5 projections not readily 230.24 Clearances Depth of burial 230.49 accessible to people and protection Over roofs accessible to -- 4.1 13.5 vehicles but not trucks Service head Terminal box, Over roofs accessible to — -- 5.6 18.5 meter,or ocher enclosure trucks Other structures 2.3 7.5 -- — — Service-entrance Part IV conductors (B) Over 22 kV Nominal to Ground. Clearances for the categories shown in Table 225.61 shall be increased by Service equipment—general Part V 10 mm (0.4 in.) per kV above 22,000 volts. Grounding and bonding Article 250 FPN: For additional information, see ANSI C2-2007, Na- tional Electrical Safety Code. Disconnecting means Parr VI Overcurrenl protection Part VII Branch circuits Articles 210,225 ARTICLE 230 Feeders Articles 215,225 Services Figure 2304 Services. 230.1 Scope. This article covers service conductors and equipment for control and protection of services and their (4) Optional standby systems installation requirements. (5) Parallel power production systems (6) Systems designed for connection to multiple sources of FPN: See Figure 230.1. supply for the purpose of enhanced reliability (B) Special Occupancies. By special permission, additional 1. General services shall be permitted for either of the following: 230.2 Number of Services. A building or other structure (1) Multiple-occupancy buildings where there is no served shall be supplied by only one service unless permitted available space for service equipment accessible to in 230.2(A)through(D).For the purpose of 230.40,Exception all occupants No. 2 only, underground sets of conductors, 110 AWG and (2) A single building or other structure sufficiently large to larger, running to the same location and connected together at make two or more services necessary their supply end but not connected together at their load end (C) Capacity Requirements. Additional services shall be shall be considered to be supplying one service. permitted under any of the following: (A) Special Conditions. Additional services shall be per- (1) Where the capacity requirements are in excess of 2000 muted to supply the following: amperes at a supply voltage of 600 volts or less (2) Where the load requirements of a single-phase installa- (1) Fire pumps tion are greater than the serving agency normally sup- (2) Emergency systems plies through one service (3) Legally required standby systems (3) By special permission 2008 Edition NATIONAL ELECTRICAL CODE 70-73 230.3 ARTICLE 230—SERVICES (D) Different Characteristics. Additional services shall porches, balconies, ladders, stairs, fire escapes, or similar be permitted for different voltages, frequencies, or phases, locations. or for different uses, such as for different rate schedules. Exception: Conductors run above the top level of a win- (E) Identification. Where a building or structure is sup- dow shall be permitted to be less than the 900-mm (3 ft) plied by more than one service, or any combination of requirement. branch circuits, feeders, and services, a permanent plaque or directory shall be installed at each service disconnect (B} Vertical Clearance. The vertical clearance of final spans above,or within 900 mm (3 ft) measured horizontally location denoting all other services, feeders, and branch of, platforms, projections, or surfaces from which they circuits supplying that building or structure and the area might be reached shall be maintained in accordance with served by each. See 225.37. 230.24(B). 230.3 One Building or Other Structure Not to Be Sup- (C) Building Openings. Overhead service conductors plied Through Another. Service conductors supplying a shall not be installed beneath openings through which ma- building or other structure shall not pass through the inte- terials may be moved, such as openings in farm and com- rior of another building or other structure. mercial buildings, and shall not be installed where they obstruct entrance to these building openings. 230.6 Conductors Considered Outside the Building. Conductors shall be considered outside of a building or 230.10 Vegetation as Support. Vegetation such as trees other structure under any of the following conditions: shall not be used for support of overhead service con- (1) Where installed under not less than 50 mm (2 in.) of ductors. concrete beneath a building or other structure (2) Where installed within a building or other structure in a II. Overhead Service-Drop Conductors raceway that is encased in concrete or brick not less than 50 mm (2 in.) thick 230.22 Insulation or Covering. Individual conductors (3) Where installed in any vault that meets the construction shall be insulated or covered. requirements of Article 450, Part III Exception: The grounded conductor of a multiconductor (4) Where installed in conduit and under not less than cable shall be permitted to be bare. 450 mm (18 in.) of earth beneath a building or other structure 230.23 Size and Rating. (A) General. Conductors shall have sufficient ampacity to 230.7 Other Conductors in Raceway or Cable. Conduc- carry the current for the load as calculated in accordance tors other than service conductors shall not be installed in with Article 220 and shall have adequate mechanical the same service raceway or service cable. strength. Exception No. 1: Grounding conductors and bonding (B) Minimum Size. The conductors shall not be smaller jumper's. than 8 AWG copper or 6 AWG aluminum or copper-clad Exception No. 2: Load management control conductors aluminum. having avercurrent protection. Exception: Conductors supplying only limited loads of a 230.8 Raceway Seal. Where a service raceway enters a single branch circuit — such as small polyphase power, building or structure from an underground distribution sys- controlled water heaters, and similar loads—shall not be tem, it shall be sealed in accordance with 300.5(G). Spare smaller than 12 AWG hard-drawn copper or equivalent. or unused raceways shall also be sealed. Sealants shall be (C) Grounded Conductors.The grounded conductor shall identified for use with the cable insulation, shield, or other not be less than the minimum size as required by components. 250.24(C). 230.9 Clearances on Buildings. Service conductors and 230.24 Clearances. Service-drop conductors shall not be final spans shall comply with 230.9(A). (B), and (C). readily accessible and shall comply with 230.24(A) through (D) for services not over 600 volts, nominal. (A) Clearances. Service conductors installed as open con- ductors or multiconductor cable without an overall outer (A) Above Roofs. Conductors shall have a vertical clear- jacket shall have a clearance of not less than 900 mm (3 ft) ance of not less than 2.5 m (8 ft) above the roof surface. from windows that are designed to be opened, doors, The vertical clearance above the roof level shall be 70-74 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 230—SERVICES 230.31 maintained for a distance of not less than 900 mm (3 ft) shall provide the minimum clearances as specified in 230.9 in all directions from the edge of the roof. and 230.24. In no case shall this point of attachment be less Exception No. 1: The area above a roof surface subject to than 3.0 m (10 ft) above finished grade. pedestrian or vehicular traffic shall have a vertical clear- ance from the roof surface in accordance with the clear- 230.27 Means of Attachment.Multiconductor cables used for service drops shall be attached to buildings or other ante requirements of 230.24(B). structures by fittings identified for use with service conduc- Exception No. 2: Where the voltage between conductors tors. Open conductors shall be attached to fittings identified does not exceed 300 and the roof has a slope of 100 mm in for use with service conductors or to noncombustible, non- 300 mm(4 in. in 12 in.)or greater, a reduction in clearance absorbent insulators securely attached to the building or to 900 mm (3 ft) shall be permitted, other structure. Exception No. 3: Where the voltage between conductors does not exceed 300, a reduction in clearance above only 230.28 Service Masts as Supports. Where a service mast the overhanging portion of the roof to not less than 450 non is used for the support of service-drop conductors, it shall (18 in.) shall be permitted if(1) not more than 1.8 m (6 ft) be of adequate strength or be supported by braces or guys of service-drop conductors, 1.2 m (4 ft) horizontally, pass to withstand safely the strain imposed by the service drop. above the roof overhang, and (2) they are terminated at a Where raceway-type service masts are used, all raceway through-the-roof raceway or approved support. fittings shall be identified for use with service masts. Only power service-drop conductors shall be permitted to be at- tached to a service mast. Exception No. 4: The requirement for maintaining the ver- tical clearance 900 min(3 ft)front the edge of the roof shall 230,29 Supports over Buildings. Service-drop conductors not apply to the final conductor span where the .service passing over a roof shall be secure) supported b substan- p �� g Y � PP Y• drop is attached to the side of a building. tial structures. Where practicable, such supports shall be (B) Vertical Clearance for Service-Drop Conductors. Independent of the building. Service-drop conductors, where not in excess of 600 volts, nominal, shall have the following minimum clearance from III. Underground Service-Lateral Conductors final grade: (1) 3.0 m (l0 ft) — at the electrical service entrance to 230.30 Insulation. Service-lateral conductors shall be in- buildings, also at the lowest point of the drip loop of sulated for the applied voltage. the building electrical entrance, and above areas or Exception: A grounded conductor shall be permitted to be sidewalks accessible only to pedestrians, measured uninsulated as follows: from final grade or other accessible surface only for service-drop cables supported on and cabled together (1) Bare copper used in a raceway. with a grounded bare messenger where the voltage (2) Bare copper for direct burial where bare copper it does not exceed 150 volts to ground judged to be suitable for the soil conditions. (2) 3.7 m (12 ft) — over residential property and drive- (3) Bare copper far direct burial without regard to soil ways, and those commercial areas not subject to truck conditions where part of a cable assembly identified for traffic where the voltage does not exceed 300 volts to underground use. ground (4) Aluminum or copper-clad aluminum without individual (3) 4.5 m (I5 ft) -- for those areas listed in the 3.7-m insulation or covering where part of a cable assembly (12-ft) classification where the voltage exceeds 300 identified for underground use in a raceway or for di- volts to ground rect burial. (4) 5.5 m(18 ft)--over public streets, alleys, roads, park- ing areas subject to truck traffic, driveways on other 230.31 Size and Rating. than residential property, and other land such as culti- (A) General. Service-lateral conductors shall have sulli- vated, grazing, forest, and orchard cient ampacity to carry the current for the load as calculated (C) Clearance from Building Openings. See 230.9. in accordance with Article 220 and shall have adequate mechanical strength. (D) Clearance from Swimming Pools. See 680.8. (B) Minimum Size. The conductors shall not be smaller 230.26 Point of Attachment. The point of attachment of than 8 AWG copper or 6 AWG aluminum or copper-clad the service-drop conductors to a building or other structure aluminum. 2008 Edition NATIONAL ELECTRICAL.CODE 70--75 230.32 ARTICLE 230—SERVICES Erception: Conductors .supphing only limited loads of a (1) Bare copper used in a raceway or part of u service single branch circuit — such as .small poh7rhase power, cable assembly. controlled water heaters, and similar loads—shall not be (2) Bare copper for direct burial where bare copper is smaller than 12 A WG copper or 10 AWG aluminum or judged to be suitable for the sail conditions. copper-clod aluttrintun. (3) Bare copper for direct burial without regard to .soil (C) Grounded Conductors.The grounded conductor shall conditions where part of a cable assembly identified for not be less than the minimum size required by 250.24(C). underground use. (4) Aluminum or copper-clad aluminum without individual 230.32 Protection Against Damage. Underground insulation or covering where part of a cable assembly service-lateral conductors shall be protected against dam- or identified for underground use in a raceway, or for age in accordance with 300.5. Service-lateral conductors direct burial. entering a building shall be installed in accordance with (5) Bare conductors used in an auxiliary grater. 230.6 or protected by a raceway wiring method identified in 230.43. 230.42 Minimum Size and Rating. 230.33 Spliced Conductors. Service-lateral conductors (A) General. The ampacity of the service-entrance con- shall be permitted to be spliced or tapped in accordance ductors before the application of any adjustment or correc- with 110.14, 300.5(E), 300.13, and 300.15. tion factors shall not be less than either (A)(1) or (A)(2). Loads shall be determined in accordance with Part III, IV, IV. Service-Entrance Conductors or V of Article 220, as applicable.Ampacity shall be deter- mined from 310.15. The maximum allowable current of 230.40 Number of Service-Entrance Conductor Sets. busways shall be that value for which the busway has been Each service drop or lateral shall supply only one set of listed or labeled. service-entrance conductors. (1) The sum of the noncontinuous loads plus 125 percent Exception No. 1: A building with more than one occupancy of continuous loads shall be permitted to have one set of service-entrance can- (2) The sum of the noncontinuous load plus the continuous ductors for each service, as defined in 230.2, run to each load if the service-entrance conductors terminate in an occupancy or group of occupancies. overcurrent device where both the overcurrent device Exception No. 2: Where two to six service disconnecting and its assembly are listed for operation at 100 percent means in separate enclosures are grouped at one location of their rating and supply separate loads from one service drop or lateral, (B) Specific Installations. In addition to the requirements one set of service-entrance conductors shall be permitted to of 230.42(A), the minimum ampacity for ungrounded con- supply each or several such service equipment enclosures. ductors for specific installations shall not be less than the Exception No. 3: A .single famil' dwelling taut and a sepa- rating of the service disconnecting means specified in rate structure shall be permitted to have one set of service- 230.79(A) through (D), entrance conductors run to each from a single service drop or lateral. (C) Grounded Conductors.The grounded conductor shall Exception No. 4: A two fantily dwelling or a nu ltifamily not be smaller than the minimum size as required by dwelling shall be permitted to have one set of service- 250.24(C). entrance conductors installed to supply the circuits covered 230.43 Wiring Methods for 600 Volts, Nominal,or Less. in 210.25. Service-entrance conductors shall be installed in accor- Exception No. 5: One .set of.service-entrance conductors dance with the applicable requirements of this Code cover- connected to the supply side of the normal service discon- ing the type of wiring method used and shall be limited to necting means shall be permitted to supply each or several the following methods: systems covered by 230.82(5) or 230.82(6). (1) Open wiring on insulators 230.41 Insulation of Service-Entrance Conductors. (2) Type IGS cable Service-entrance conductors entering or on the exterior of (3) Rigid metal conduit buildings or other structures shall be insulated. (4) Intermediate metal conduit Exception: A grounded conductor shall be permitted to be (5) Electrical metallic tubing uninsulated as follows: (6) Electrical nonmetallic tubing (ENT) 70-76 NATIONAL.ELECTRICAL CODE 2008 Edition ARTICLE 230—SERVICES 230.54 (7) Service-entrance cables (4) Electrical metallic tubing (8) Wireways (5) Other approved means (4) Busways (2) Other Than Service Cable. Individual open conduc- (10) Auxiliary gutters tors and cables, other than service cables, shall not be in- (11) Rigid nonmetallic conduit stalled within 3.0 m (10 ft) of grade level or where exposed (12) Cablebus to physical damage. (13) Type MC cable Exception: Type MI and Type MC cable shall be permitted (14) Mineral-insulated, metal-sheathed cable within 3.0 m (]Oft) of grade level where not exposed to (15) Flexible metal conduit not over 1.8 m (6 ft) long or physical damage or where protected in accordance with liquidtight flexible metal conduit not over 1.8 m (6 ft) 300.5(D). long between raceways, or between raceway and ser- vice equipment, with equipment bonding jumper 230.51 Mounting Supports. Cables or individual open routed with the flexible metal conduit or the liq- service conductors shall be supported as specified in uidtight flexible metal conduit according to the provi- 230.51(A), (B), or (C). sions of 250.102(A), (B), (C), and (E) (A) Service Cables. Service cables shall be supported by (16) Liquidtight flexible nonmetallic conduit straps or other approved means within 300 mm (12 in.) of every service head, gooseneck,or connection to a raceway or 230.44 Cable"Days. Cable tray systems shall be permitted enclosure and at intervals not exceeding 750 mm{30 in.). to support service-entrance conductors. Cable trays used to support service-entrance conductors shall contain only (B) Other Cables. Cables that are not approved for service-entrance conductors. mounting in contact with a building or other structure shall Exception: Conductors, other than service-entrance con- be mounted on insulating supports installed at intervals not ductors, shall be permitted to be installed in a cable tray exceeding 4.5 m 0 5 ft) and in a manner that maintains a with service-entrance conductors, provided a solid fixed clearance of not less than 50 mm (2 in.) from the surface barrier of a material compatible with the cable tray is over which they pass. installed to separate the service-entrance conductors from (C) Individual Open Conductors. Individual open con- other conductors installed in the cable tray. Cable trays ductors shall be installed in accordance with Table shall be identified with permanently affixed labels with the 230.51(C). Where exposed to the weather, the conductors wording "Service-Entrance Conductors." The labels shall shall be mounted on insulators or on insulating supports be located so as to be visible after installation and placed attached to racks, brackets, or other approved means. so that the service-entrance conductors may be readily Where not exposed to the weather, the conductors shall be traced through the entire length of the cable tray. mounted on glass or porcelain knobs. 230.46 Spliced Conductors. Service-entrance conductors 230.52 individual Conductors Entering Buildings or shall be permitted to be spliced or tapped in accordance Other Structures.Where individual open conductors enter with 110.14, 300.5(E), 300.13, and 300.15. a building or other structure, they shall enter through roof bushings or through the wall in an upward slant through 230.50 Protection Against Physical Damage. individual, noncombustible, nonabsorbent insulating tubes. (A) Underground Service-Entrance Conductors. Under- Drip loops shall be formed on the conductors before they ground service-entrance conductors shall be protected enter the tubes. against physical damage in accordance with 300.5. 230.53 Raceways to Drain. Where exposed to the (B) AIL Other Service-Entrance Conductors. All other Weather, raceways enclosing service-entrance conductors service-entrance conductors, other than underground ser- shall be suitable for use in wet locations and arranged to vice entrance conductors, shall be protected against physi- drain. Where embedded in masonry, raceways shall be ar- cal damage as specified in 230.50(B)(1) or (B)(2). ranged to drain. (1) Service Cables.Service cables,where subject to physi- 230.54 Overhead Service Locations. cal damage, shall be protected by any of the following: (A) Service Head. Service raceways shall be equipped (1) Rigid metal conduit with a service head at the point of connection to service- (2) Intermediate metal conduit drop conductors. The service head shall comply with the (3) Schedule 80 PVC conduit requirement for fittings in 314.15. 2008 Edition NATIONAL ELECTRICAL CODE 70-77 230.56 ARTICLE 230—SERVICES Table 230.51(C) Supports Minimum Clearance Maximum Distance Between Supports Between Conductors From Surface Maximum - Volts in ft mm in. mm in. 600 2.7 9 150 6 50 2 600 4.5 15 300 12 50 2 300 14 41/2 75 3 50 2 600* 14* 4112* 65* 21/z* 25* 1* *Where not exposed to weather. (B) Service Cable Equipped with Service Head or conductor having the higher phase voltage to ground shall Gooseneck.Service cables shall he equipped with a service be durably and permanently marked by an outer finish that head. The service head shall comply with the requirement is orange in color, or by other effective means, at each for fittings in 314.15. termination or junction point. Exception: Type SE cable shall be permitted to be formed in a gooseneck and taped with a self-sealing weather- V. Service Equipment-- General resistant thermoplastic. 230.62 Service Equipment—Enclosed or Guarded.En- (C) Service Heads and Goosenecks Above Service-Drop ergized parts of service equipment shall be enclosed as Attachment. Service heads and goosenecks in service- specified in 230.62(A) or guarded as specified in entrance cables shall be located above the point of attach- 230.62(B). ment of the service-drop conductors to the building or other structure. (A) Enclosed. Energized parts shall be enclosed so that they will not be exposed to accidental contact or shall be Exception: Where it is impracticable to locate the service guarded as in 230.62(13}. head or gooseneck above the paint of attachment, the ser- vice head or gooseneck location shall be permitted not (B) Guarded. Energized parts that are not enclosed shall farther than 600 mm (24 in.)from the point of attachment. be installed on a switchboard, panelboard, or control board (D) Secured. Service cables shall be held securely in and guarded in accordance with 110.18 and 110.27. Where energized parts are guarded as provided in 110.27(A)(1) place. and (A)(2), a means for locking or sealing doors providing (E) Separately Bushed Openings. Service heads shall access to energized parts shall be provided. have conductors of different potential brought out through separately bushed openings. 230.66 Marking. Service equipment rated at 600 volts or less shall be marked to identify it as being suitable for use Exception: For jacketed nndricondactor service cable as service equipment. Individual meter socket enclosures without splice. shall not be considered service equipment. (F) Drip Loops. Drip loops shall be formed on individual conductors. To prevent the entrance of moisture, service- VI. Service Equipment—Disconnecting Means entrance conductors shall be connected to the service-drop conductors either(1) below the level of the service head or 230.70 General. Means shall be provided to disconnect all (2) below the level of the termination of the service- conductors in a building or other structure from the service- entrance cable sheath, entrance conductors. (G) Arranged That Water Will Not Enter Service Race- (A) Location. The service disconnecting means shall be way or Equipment. Service-drop conductors and service- installed in accordance with 230.70(A)(I), (A)(2), and entrance conductors shall be arranged so that water will not (A)(3). enter service raceway or equipment, (1) Readily Accessible Location. The service disconnect- 230.56 Service Conductor with the Higher Voltage to ing means shall be installed at a readily accessible location Ground. On a 4-wire, delta-connected service where the either outside of a building or structure or inside nearest the midpoint of one phase winding is grounded, the service point of entrance of the service conductors. 70-78 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 230—SERVICES 230.79 (2) Bathrooms. Service disconnecting means shall not be intended to provide fire protection, shall be permitted to be installed in bathrooms. located remote f om the other disconnecting means. (3) Remote Control. Where a remote control device(s) is (B) Additional Service Disconnecting Means.The one or used to actuate the service disconnecting means,the service more additional service disconnecting means for fire disconnecting means shall be located in accordance with pumps,emergency systems, legally required standby,or op- 230.70(A)(1). tional standby services permitted by 230.2 shall be installed remote from the one to six service disconnecting means for (B) Marking. Each service disconnect shall be perms- normal service to minimize the possibility of simultaneous nently marked to identify it as a service disconnect. interruption of supply. (C) Suitable for Use. Each service disconnecting means (C) Access to Occupants. In a multiple-occupancy build- shall be suitable for the prevailing conditions. Service ing, each occupant shall have access to the occupant's ser- equipment installed in hazardous (classified) locations shall vice disconnecting means. comply with the requirements of Articles 500 through 517. Exception: In amultiple-occupancy building where elec- 230.71 Maximum Number of Disconnects. tric service and electrical maintenance are provided by the building management and where these are under continu- (A) General. The service disconnecting means for each ous building management supervision, the service discon- service permitted by 230.2, or for each set of service- netting means supplying more than one occupancy shall be entrance conductors permitted by 230.40, Exception No. 1, permitted to be accessible to authorized management per- 3,4,or 5,shall consist of not more than six switches or sets sonnel only. of circuit breakers, or a combination of not more than six switches and sets of circuit breakers, mounted in a single 230.74 Simultaneous Opening of Poles. Each service dis- enclosure, in a group of separate enclosures, or in or on a connect shall simultaneously disconnect all ungrounded switchboard. There shall be not more than six sets of dis- service conductors that it controls from the premises wiring connects per service grouped in any one location. system. For the purpose of this section, disconnecting means in- stalled as part of listed equipment and used solely for the 230.75 Disconnection of Grounded Conductor. Where following shall not be considered a service disconnecting the service disconnecting means does not disconnect the means: grounded conductor from the premises wiring, other means (1) Power monitoring equipment shall be provided for this purpose in the service equipment. (2) Surge-protective device(s) A terminal or bus to which all grounded conductors can be attached by means of pressure connectors shall be permit- (3) Control circuit of the ground-fault protection system ted for this purpose. In a multisection switchboard, discon- (4) Power-operable service disconnecting means netts for the grounded conductor shall be permitted to be in (B) Single-Pole Units. Two or three single-pole switches any section of the switchboard, provided any such switch- or breakers, capable of individual operation, shall be per- board section is marked. mitted on multiwire circuits, one pole for each ungrounded 230.76 Manually or Power Operable. The service dis- conductor, as one multipole disconnect, provided they are connecting means for ungrounded service conductors shall equipped with identified handle ties or a master handle to consist of one of the following: disconnect all conductors of the service with no more than six operations of the hand. (]) A manually operable switch or circuit breaker equipped with a handle or other suitable operating means FPN: See 409.36, Exceptions No. 1 and Exception No. 3, (2) A power-operated switch or circuit breaker, provided for service equipment in certain panelboards, and see the switch or circuit breaker can be opened by hand in 430.95 for service equipment in motor control centers. the event of a power supply failure 230.72 Grouping of Disconnects. 230.77 Indicating. The service disconnecting means shall (A) General. The two to six disconnects as permitted in plainly indicate whether it is in the open or closed position. 230.71 shall be grouped. Each disconnect shall be marked 230.79 Rating of Service Disconnecting Means. The set- to indicate the load served. vice disconnecting means shall have a rating not less than Exception: One of the two to six service disconnecting means the calculated load to be carried, determined in accordance permitted in 230.71, where used only for a water pump also with Part 111, IV, or V of Article 220, as applicable. In no 2008 Edition NATIONAL ELECTRICAL CODE 70-79 230.80 ARTICLE 230—SERVICES case shall the rating be lower than specified in 230.79(A), service equipment and installed in accordance with re- (B), (C), or (D), quirements for service-entrance conductors. (A) One-Circuit Installations. For installations to supply (6) Solar photovoltaic systems, fuel cell systems, or inter- only limited loads of a single branch circuit, the service connected electric power production sources, disconnecting means shall have a rating of not less than 15 (7) Control circuits for power-operable service disconnect- amperes. ing means, if suitable overcurrent protection and dis- connecting means are provided. (B) Two-Circuit Installations. For installations consisting (8) Ground-fault protection systems or Type 2 surge- of not more than two 2-wire branch circuits, the service protective devices, where installed as part of listed disconnecting means shall have a rating of not less than 30 equipment, if suitable overcurrent protection and dis- amperes. connecting means are provided. (C) One-Family Dwellings. For a one-family dwelling, the service disconnecting means shall have a rating of not VII. Service Equipment— Overcurrent Protection less than 100 amperes, 3-wire. 230.90 Where Required. Each ungrounded service con- (D) All Others. For all other installations, the service dis- ductor shall have overload protection. connecting means shall have a rating of not less than 60 (A) Ungrounded Conductor, Such protection shall be amperes. provided by an overcurrent device in series with each un- 230.80 Combined Rating of Disconnects. Where the sec grounded service conductor that has a rating or setting not vice disconnecting means consists of more than one switch higher than the allowable ampacity of the conductor. A set of fuses shall be considered all the fuses required to protect or circuit breaker, as permitted by 230.71, the combined ratings of all the switches or circuit breakers used shall not all the ungrounded conductors of a circuit. Single-pole cir- cuit breakers, grouped in accordance with 230.71(B), shall be less than the rating required by 230.79. be considered as one protective device. 230.81 Connection to Terminals. The service conductors Exception No. 1: For motor-starting currents, ratings that shall be connected to the service disconnecting means by comply with 430.52, 430.62, and 430.63 shall be permitted. pressure connectors, clamps, or other approved means. Exception No. 2: Fuses and circuit breakers with a rating Connections that depend on solder shall not be used. or setting that complies with 240.4(B) or (C) and 240.6 230.82 Equipment Connected to the Supply Side of Ser- shall be permitted. vice Disconnect. Only the following equipment shall be Exception No. 3: Two to six circuit breakers or sets of fuses permitted to be connected to the supply side of the service shall be permitted as the overcurrent device to provide the disconnecting means: overload protection. The sum of the ratings of the circuit (1) Cable limiters or other current-limiting devices. breakers or fuses shall be permitted to exceed the ampacity (2) Meters and meter sockets nominally rated not in excess of the service conductors, provided the calculated load of 600 volts, provided all meta] housings and service does not exceed the ampacity of the service conductors. enclosures are grounded in accordance with Part VII Exception No. 4: Overload protections for fire pump supply and bonded in accordance with Part V of Article 250. conductors shall comply with 695.4(B)(1). (3) Meter disconnect switches nominally rated not in ex- Exception No. 5: Overload protection for 1201240-volt, cess of 600 volts that have a short-circuit current rating 3-wire, single-phase dwelling services shall be permitted in equal to or greater than the available short-circuit cur- accordance with the requirements of 310.15(B)(6), rent, provided all metal housings and service enclo- sures are grounded in accordance with Part VII and (B) Not in Grounded Conductor. No overcurrent device bonded in accordance with Part V of Article 250. A shall be inserted in a grounded service conductor except a circuit breaker that simultaneously opens all conductors of meter disconnect switch shall be capable of interrupt- ing the load served. the circuit. (4) Instrument transformers (current and voltage), imped- 230.91 Location. The service overcurrent device shall be ance shunts, Ioad management devices, surge arresters, an integral part of the service disconnecting means or shall and Type 1 surge-protective devices. be located immediately adjacent thereto. (5) Taps used only to supply load management devices, circuits for standby power systems, fire pump equip- 230.92 Locked Service Overcurrent Devices. Where the ment, and fire and sprinkler alarms, if provided with service overcurrent devices are locked or sealed or are not 70-80 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 230—SERVICES 230.200 readily accessible to the occupant, branch-circuit overcur- Exception: The ground fault protection provisions of this rent devices shall be installed on the load side, shall be section shall not apply to a service disconnect for a con- mounted in a readily accessible location, and shall be of tinuous industrial process where a nonorderly shutdown lower ampere rating than the service overcurrent device. will introduce additional or increased hazards. 230.93 Protection of Specific Circuits. Where necessary (A) Setting. The ground-fault protection system shall op- to prevent tampering, an automatic overcurrent device that erate to cause the service disconnect to open all ungrounded protects service conductors supplying only a specific load, conductors of the faulted circuit.The maximum setting of the such as a water heater, shall be permitted to be locked or ground-fault protection shall be 1200 amperes, and the maxi- sealed where located so as to be accessible. mum time delay shall be one second for ground-fault currents 230.94 Relative Location of Overcurrent Device and equal to or greater than 3000 amperes. Other Service Equipment. The overcurrent device shall (B) Fuses. If a switch and fuse combination is used, the protect all circuits and devices, fuses employed shall be capable of interrupting any current Exception No. 1: The service switch shall be permitted on higher than the interrupting capacity of the switch during a the supply side. time that the ground-fault protective system will not cause Exception No. 2: High-impedance shunt circuits, surge ar- the switch to open. resters, Type 1 Surge protective devices, surge-protective (C) Performance Testing. The ground-fault protection capacitors, and instrument transformers (current and volt- system shall be performance tested when first installed on age)shall be permitted to be connected and installed on the site.The test shall be conducted in accordance with instruc- supply side of the service disconnecting means as permitted lions that shall be provided with the equipment. A written b1 230.82. record of this test shall be made and shall be available to Exception No. 3: Circuits for load management devices the authority having jurisdiction, shall be permitted to be connected on the supply side of the the No. 1: Ground-fault protection that functions to open service overcurrent device where separately provided with the service disconnect affords no protection from faults on overcurrent protection. the line side of the protective element. It serves only to Exception No. 4: Circuits used only for the operation of limit damage to conductors and equipment on the load side fire alarm, other protective signaling systems, or the supply in the event of an arcing ground fault on the load side of the to fire pump equipment shall be permitted to be connected protective element. on the supply side of the service overcurrent device where FPN No. 2: This added protective equipment at the service separately provided with overcurrent protection. equipment may make it necessary to review the overall wiring system for proper selective overcurrent protection Exception No. S: Meters nominally rated not in excess of coordination. Additional installations of ground-fault pro- 600 volts shall be permitted, provided all metal housings tective equipment may be needed on feeders and branch and service enclosures are grounded. circuits where maximum continuity of electric service is necessary. Exception No. 6: Where service equipment is power oper- able, the control circuit shall be permitted to be connected the No.service Where ground-fault protection is provided for the e disconnect and interconnection is made with ahead of the service equipment if suitable overcurrent pro- another supply system by a transfer device, means or de- tection and disconnecting means are provided, vices may be needed to ensure proper ground-fault sensing by the ground-fault protection equipment. 230.95 Ground-Fault Protection of Equipment.Ground- FPN No. 4: See 517.17(A) for information on where an fault protection of equipment shall be provided for solidly additional step of ground-fault protection is required for grounded wye electric services of more than 150 volts to hospitals and other buildings with critical areas or life sup- ground but not exceeding 600 volts phase-to-phase for each port equipment. service disconnect rated 1000 amperes or more. The grounded conductor for the solidly grounded wye system VIII. Services Exceeding 600 Volts, Nominal shall be connected directly to ground through a grounding electrode System, as specified in 250.50, without inserting 230.200 General. Service conductors and equipment used any resistor or impedance device. on circuits exceeding 600 volts, nominal, shall comply with The rating of the service disconnect shall be considered all the applicable provisions of the preceding sections of to be the rating of the largest fuse that can be installed or this article and with the following sections that supplement the highest continuous current trip setting for which the or modify the preceding sections. In no case shall the pro- actual overcurrent device installed in a circuit breaker is visions of Part VIII apply to equipment on the supply side rated or can be adjusted. of the service point. 2008 Edition NATIONAL ELECTRICAL CODE 70-81 230.202 ARTICLE 230—SERVICES FPN: For clearances of conductors of over 600 volts, shall be permitted to be located in a location that is not nominal, see ANSI C2-2007, National Electrical Safety matey accessible. Code. (B) Type. Each service disconnect shall simultaneously 230.202 Service-Entrance Conductors. Service-entrance disconnect all ungrounded service conductors that it con- conductors to buildings or enclosures shall be installed to tools and shall have afault-closing rating that is not less conform to 230.2b2{A) and {B}. than the maximum short-circuit current available at its sup- (A) Conductor Size.Service-entrance conductors shall not ply terminals. be smaller than 6 AWG unless in multiconductor cable. Where fused switches or separately mounted fuses are Multiconductor cable shall not be smaller than 8 AWG. installed, the fuse characteristics shall be permitted to con- tribute to the fault-closing rating of the disconnecting (B) Wiring Methods. Service-entrance conductors shall means. be installed by one of the wiring methods covered in 300.37 and 300.50. (C) Remote Control. For multibuilding, industrial instal- lations under single management, the service disconnecting 230.204 Isolating Switches. means shall be permitted to be located at a separate build- (A) Where Required. Where oil switches or air, oil, ing or structure. In such cases, the service disconnecting means shall be permitted to be electrically operated by a vacuum, or sulfur hexafluoride circuit breakers constitute the service disconnecting means, an isolating switch with readily accessible, remote-control device, visible break contacts shall be installed on the supply side 230.206 Overcurrent Devices as Disconnecting Means. of the disconnecting means and all associated service Where the circuit breaker or alternative for it, as specified equipment. in 230.208 for service overcurrent devices, meets the re- Exception: An isolating switch shall not be required where quirements specified in 230.205, they shall constitute the the circuit breaker or switch is mounted on removable truck service disconnecting means. pastels or metal-enclosed sxdtchgear units where both of the following conditions apply: 230.208 Protection Requirements. A short-circuit protec- (1) Cannot be opened sonless the circuit is disconnected. tive device shall be provided on the load side of, or as an (2) Where all eneigized parts are automatically discos- integral part of, the service disconnect, and shall protect all nected when the circuit breaker or switch is removed ungrounded conductors that it supplies. The protective de- frorst the normal operating position. vice shall be capable of detecting and interrupting all val- ues of current, in excess of its trip setting or melting point, (B) Fuses as Isolating Switch.Where fuses are of the type that can occur at its location. A fuse rated in continuous am- that can be operated as a disconnecting switch,a set of such peres not to exceed three times the ampacity of the conductor, fuses shall be permitted as the isolating switch. or a circuit breaker with a trip setting of not more than six times the ampacity of the conductors, shall be considered as (C) Accessible to Qualified Persons Only. The isolating providing the required short-circuit protection. switch shall be accessible to qualified persons only. FPM: See Table 310.67 through Table 310.86 for ampaci- (D) Connection to Ground. Isolating switches shall be ties of conductors rated 2001 volts and above. provided with a means for readily connecting the load side conductors to a grounding electrode system, equipment Overcurrent devices shall conform to 230.208(A)and(B). ground bulbar, or grounded steel Structure when discon- nected from the source of supply. (A) Equipment'I�pe. Equipment used to protect service- entrance conductors shall meet the requirements of Article A means for grounding the load side conductors to a 490, Part II. grounding electrode system, equipment grounding bulbar, or grounded structural steel shall not be required for any (B) Enclosed Overcurrent Devices. The restriction to duplicate isolating switch installed and.maintained by the 80 percent of the rating for an enclosed overcurrent device electric supply company. for continuous loads shall not apply to overcurrent devices 230.205 Disconnecting Means. installed in systems operating at over 600 volts. (A) Location. The service disconnecting means shall be 230.209 Surge Arresters (Lightning Arresters). Surge located in accordance with 230.70, arresters installed in accordance with the requirements of For either overhead or underground primary distribu- Article 280 shall be permitted on each ungrounded over- tion systems on private property, the service disconnect head service conductor. 70-82 NATIONAL ELECTRICAL CODE 2009 Edition ARTICLE 240—OVERCURRENT PROTECTION 240,4 230.210 Service Equipment— General Provisions. Ser- (3) The premises has at least one service or feeder that is vice equipment, including instrument transformers, shall more than 150 volts to ground and more than 300 volts conform to Article 490, Part I. phase-to-phase. 230.211 Metal-Enclosed Switchgear. Metal-enclosed This definition excludes installations in buildings used switchgear shall consist of a substantial metal structure and by the industrial facility for offices, warehouses, garages, a sheet metal enclosure.Where installed over a combustible machine shops, and recreational facilities that are not an floor, suitable protection thereto shall be provided. integral part of the industrial plant, substation, or control center. 230.212 Over 35,000 Volts. Where the voltage exceeds 35,000 volts between conductors that enter a building, they Tap Conductors.As used in this article, a tap conductor is shall terminate in ametal-enclosed switchgear comport- defined as a conductor, other than a service conductor, that a vault conforming to the requirements of 450.41 has overcurrent protection ahead of its point of supply that ment or through a vain. exceeds the value permitted for similar conductors that are protected as described elsewhere in 240.4. 240.3 Other Articles. Equipment shall be protected against overcurrent in accordance with the article in this ARTICLE 240 Code that covers the type of equipment specified in Table Overcurrent Protection 240.3. I. General 240.4 Protection of Conductors. Conductors, other than flexible cords, flexible cables, and fixture wires, shall be 240.1 Scope. Parts I through VII of this article provide the protected against overcurrent in accordance with their am- general requirements for overcurrent protection and over- pacities specified in 310.15, unless otherwise permitted or current protective devices not more than 600 volts, nomi- required in 240.4(A) through (G). nal. Part ViIl covers overcurrent protection for those por- tions of supervised industrial installations operating at (A) Power Loss Hazard. Conductor overload protection voltages of not more than 600 volts, nominal. Part IX cov- shall not be required where the interruption of the circuit ers overcurrent protection over 600 volts, nominal. would create a hazard, such as in a material-handling mag- FPN: Overcurrent protection For conductors and equipment net circuit or fire pump circuit. Short-circuit protection is provided to open the circuit if the current reaches a value shall be provided. that will cause an excessive or dangerous temperature in conductors or conductor insulation. See also 110.9 for re- quirements of for interrupting ratings and 110.10 for require- 5tatinnrrn Pumps for Fire Protection. ments for protection against fault currents. (B) Devices Rated 800 Amperes or Less.The next higher 240.2 Definitions. standard overcurrent device rating (above the ampacity of Current-Limiting Overcurrent Protective Device. A de- the conductors being protected) shall be permitted to be vice that, when interrupting currents in its current-limiting used, provided all of the following conditions are met: range, reduces the current flowing in the faulted circuit to a (1) The conductors being protected are not part of a mul- magnitude substantially less than that obtainable in the tioutlet branch circuit supplying receptacles for cord- same circuit if the device were replaced with a solid con- and-plug-connected portable loads. ductor having comparable impedance. (2) The ampacity of the conductors does not correspond with the standard ampere rating of a fuse or a circuit Supervised Industrial Installation. For the purposes of breaker without overload trip adjustments above its rat- Part VIII, the industrial portions of a facility where all of ing (but that shall be permitted to have other trip or the following conditions are met: rating adjustments). (1) Conditions of maintenance and engineering supervision (3) The next higher standard rating selected does not ex- ensure that only qualified persons monitor and service teed 800 amperes. the system. (2) The premises wiring system has 2500 kVA or greater of (C) Devices Rated over 800 Amperes. Where the over- load used in industrial process(es), manufacturing ac- current device is rated over 800 amperes, the ampacity of tivities, or both, as calculated in accordance with Ar- the conductors it protects shall be equal to or greater than title 220. the rating of the overcurrent device defined in 240.6. 2009 Edition NATIONAL ELECTRICAL CODE 70-83 240.4 ARTICLE 240—OVERCURRENT PROTECTION Table 240.3 Other Articles (1) Continuous loads do not exceed 5.6 amperes. (2) Overcurrent protection is provided by one of the fol- Equipment Article lowing: Air-conditioning and refrigerating 440 a. Branch-circuit-rated Circuit breakers listed and equipment marked for use with 18 AWG copper wire Appliances 422 b. Branch-circuit-rated fuses listed and marked for use Assembly occupancies 518 Audio signal processing, 640 with 18 AWG copper wire amplification, and reproduction e. Class CC, Class T, or Class T fuses equipment Branch circuits 210 (2) 16 AWG Copper. 10 amperes,provided all the follow- Susways 368 ing conditions are met: Capacitors 460 (1) Continuous loads do not exceed 8 amperes. Class 1, Class 2, and Class 3 725 remote-control, signaling, and (2) Overcurrent protection is provided by one of the fol- power-limited circuits lowing: Cranes and hoists 610 a. Branch-circuit-rated circuit breakers listed and Electric signs and outline lighting 600 marked for use with 16 AWG copper wire Electric welders 630 Electrolytic cells 668 b. Branch-circuit-rated fuses listed and marked for use Elevators, dumbwaiters, escalators, 620 with 16 AWG copper wire moving walks, wheelchair lifts, and c. Class CC, Class 1, or Class T fuses stairway chairlifts Emergency systems 700 (3) 14 AWG Copper. 15 amperes Fire alarm systems 760 Fire pumps 695 (4) 12 AWG Aluminum and Copper-Clad Aluminum. Fixed electric heating equipment for 427 15 amperes pipelines and vessels Fixed electric space-heating 424 (5) 12 AWG Copper. 20 amperes equipment Fixed outdoor electric deicing and 426 (6) 10 AWG Aluminum and Copper-Clad Aluminum. snow-melting equipment 25 amperes Generators 445 Health care facilities 517 (7) 10 AWG Copper. 30 amperes Induction and dielectric heating 665 equipment (E) Tap Conductors. Tap conductors shall be permitted Industrial machinery 670 Luminaires, lampholders, and lamps 410 to be protected against overcurrent in accordance with Motion picture and television studios 530 the following: and similar locations (1) 210.19(A)(3)and(A)(4),Household Ranges and Cook- Motors, motor circuits, and 430 ing Appliances and Other Loads controllers Phase converters 455 (2) 240.5(B)(2), Fixture Wire Pipe organs 650 (3) 240.21, Location in Circuit Receptacles 406 4 368.17(B), Reduction in Am acit Size of Buswa Services 230 O p Y Y Solar photovoltaic systems 690 (5) 368.17(C), Feeder or Branch Circuits (busway taps) Switchboards and panelboards 408 (6) 430.53(D), Single Motor Taps Theaters, audience areas of motion 520 picture and television studios, and similar locations (F) Transformer Secondary Conductors. Single-phase Transformers and transformer vaults 450 (other than 2-wire) and multiphase (other than delta-delta, X-ray equipment 660 3-wire) transformer secondary conductors shall not be con- sidered to be protected by the primary overcurrent protec- (D) Small Conductors. Unless specifically permitted in tive device. Conductors supplied by the secondary side Of a 240.4(E)or(G), the overcurrent protection shall not exceed single-phase transformer having a 2-wire (single-voltage) that required by (13)(1) through (D)(7) after any correction secondary, or a three-phase, delta-delta connected trans- factors for ambient temperature and number of conductors former having a 3-wire (single-voltage) secondary, shall be have been applied. permitted to be protected by overcurrent protection pro- vided on the primary (supply) side of the transformer, pro- (1) 18 AWG Copper. 7 amperes, provided all the follow- vided this protection is in accordance with 450.3 and ing conditions are met: does not exceed the value determined by multiplying the 70-84 NATIONAL ELECTRICAL COLE 20()8 Edition ARTICLE 240-OVERCURRENT PROTECTION 240.6 secondary conductor ampacity by the secondary-to- teeted, where supplied by a branch circuit, in accordance primary transformer voltage ratio, with 240,5(B)(2). (G) Overcurrent Protection for Specific Conductor Ap- (1) Supply Cord of Listed Appliance or Luminaire. plications. Overcurrent protection for the specific conduc- Where flexible cord or tinsel cord is approved for and used tors shall be permitted to be provided as referenced in Table with a specific listed appliance or luminaire, it shall be 240.4(G). considered to be protected when applied within the appliance or lu maire listing requirements.For the purposes of this sec- Table 240.4(G) Specific Conductor Applications tion, a luminaire may be either portable or permanent. Conductor Article Section (2) Fixture Wire. Fixture wire shall be permitted to be tapped to the branch-circuit conductor of a branch circuit in Air-conditioning and 440, Parts III, accordance with the following: refrigeration VI (1) 20-ampere circuits - 18 AWG, up to 15 m (50 ft) of equipment circuit run length conductors Capacitor circuit 460 460.8(8) and (2) 20-ampere circuits - 16 AWG, up to 30 m (100 ft) of conductors 460.25(A)-(D) run length Control and 727 727.9 instrumentation (3) 20-ampere circuits - 14 AWG and larger circuit conductors (4) 30-ampere circuits - 14 AWG and larger (Type ITC) (5) 40-ampere circuits - 12 AWG and larger Electric welder 630 630.12 and 630.32 circuit conductors (6) 50-ampere circuits - 12 AWG and larger Fire alarm system 760 760.43, 760.45, circuit conductors 760.121, and Chapter 9, (3) Extension Cord Sets. Flexible cord used in listed ex- Tables 12(A) and 12(13) tension cord sets shall be considered to be protected when Motor-operated 422, Part 11 applied within the extension cord listing requirements. appliance circuit conductors ( )4 Field Assembled Extension Cord Sets. Flexible cord Motor and 430, Parts 111, used in extension cords made with separately listed and motor-control IV, V, VI, VII installed components shall be permitted to be supplied by a circuit conductors branch circuit in accordance with the following: Phase converter 455 455.7 supply conductors 20-ampere circuits - 16 AWG and larger Remote-control, 725 725.43, 725.45, signaling, and 725.121, and Chapter 9, 240.6 Standard Ampere Ratings. power-limited Tables I1(A) and 11(13) circuit conductors (A) Fuses and Fixed-Trip Circuit Breakers. The stan- Secondary tie 450 450.6 dard ampere ratings for fuses and inverse time circuit conductors breakers shall be considered 15, 20, 25, 30, 35, 40, 45, 50, 60,70, 80, 90, 100, 110, 125, 150, 175, 200, 225, 250, 300, 240.5 Protection of Flexible Cords,Flexible Cables,and 350,400,450, 500, 600, 700, 800, 1000, 1200, 1600, 2000, Fixture Wires. Flexible cord and flexible cable, including 2500, 3000, 4000, 5000, and 6000 amperes. Additional tinsel cord and extension cords, and fixture wires shall be standard ampere ratings for fuses shall be 1, 3, 6, 10, and protected against overcurrent by either 240.5(A) or (B). 601.The use of fuses and inverse time circuit breakers with nonstandard ampere ratings shall be permitted. (A) AmpaeiHes. Flexible cord and flexible cable shall be protected by an overcurrent device in accordance with their (B) Adjustable-Trip Circuit Breakers. The rating of ampacity as specified in Table 4005(A) and Table adjustable-trip circuit breakers having external means for 400.5(8). Fixture wire shall be protected against overcur- adjusting the current setting (long-time pickup setting), not rent in accordance with its ampacity as specified in Table meeting the requirements of 240.6(C), shall be the maxi- 402.5. Supplementary overcurrent protection, as covered in mum setting possible. 240.10, shall be permitted to be an acceptable means for Break- providing this protection. (C) Restricted Access Adjustable-Trip Circuit Break- ers. A circuit breaker(s) that has restricted access to the (B) Branch-Circuit Overcurrent Device. Flexible cord adjusting means shall be permitted to have an ampere rat- shall be protected, where supplied by a branch circuit, in ing(s)that is equal to the adjusted current setting(long-time accordance with one of the methods described in pickup setting). Restricted access shall be defined as lo- 240.5(B)(1), (13)(3), or (8)(4). Fixture wire Shall be pro- cated behind one of the following: 2008 Edition NATIONAL ELECTRICAL CODE 70-85 240.8 ARTICLE 240--OVERCURRENT PROTECTION (1) Removable and sealable covers over the adjusting 240,15 Ungrounded Conductors. means (A) Overcurrent Device Required. A fuse or an overcur- (2) Bolted equipment enclosure doors rent trip unit of a circuit breaker shall be connected in (3) Locked doors accessible only to qualified personnel series with each ungrounded conductor.A combination of a current transformer and overcurrent relay shall be consid- 240.8 Fuses or Circuit Breakers in Parallel Fuses and Bred equivalent to an overcurrent trip unit. circuit breakers shalt be permitted to be connected in par- allel where they are factory assembled in parallel and listed FPN: For motor circuits, see Pans 111, IV, v, and XI of as a unit. Individual fuses, circuit breakers,or combinations Article 430. thereof shall not otherwise be connected in parallel. (B) Circuit Breaker as Overcurrent Device. Circuit 240.9 Thermal Devices. Thermal relays and other devices breakers shall open all ungrounded conductors of the circuit not designed to open short circuits or ground faults shall both manually and automatically unless otherwise permit- led in 240.15{B}{1), {B}(2), and {B){3). not be used for the protection of conductors against over- current due to short circuits or ground faults, but the use of (1) Muldwire Branch Circuit. Except where limited by such devices shall be permitted to protect motor branch- 210.4(B), individual single-pole circuit breakers, with or circuit conductors from overload if protected in accordance without identified handle ties, shall be permitted as the pro- with 430.40. tection for each ungrounded conductor of multiwire branch 240.10 Supplementary Overcurrent Protection. Where circuits that serve only single-phase line-to-neutral loads. supplementary overcurrent protection is used for lumi- (2) Grounded Single-Phase and 3-Wire de Circuits. In naires, appliances, and other equipment or for internal cir- grounded systems, individual single-pole circuit breakers cuits and components of equipment, it shall not be used as with identified handle ties shall be permitted as the protec- a substitute for required branch-circuit overcurrent devices tion for each ungrounded conductor for line-to-line con- or in place of the required branch-circuit protection. nected loads for single-phase circuits or 3-wire, direct- Supplementary overcurrent devices shall not be required to current circuits. be readily accessible. (3) 3-Phase and 2-Phase Systems. For line-to-line loads 240.12 Electrical System Coordination. Where an or- in 4-wire, 3-phase systems or 5-wire, 2-phase systems hav- derly shutdown is required to minimize the hazard(s) to ing a grounded neutral point and no conductor operating at personnel and equipment, a system of coordination based a voltage greater than permitted in 210.6, individual single- on the following two conditions shall be permitted: pole circuit breakers with identified handle ties shall be (I) Coordinated short-circuit protection permitted as the protection for each ungrounded conductor. (2) Overload indication based on monitoring systems or (C) Closed-Loop Power Distribution Systems.Listed de- devices vices that provide equivalent overcurrent protection in FPN: The monitoring system may cause the condition to closed-loop power distribution systems shall be permitted go to alarm, allowing corrective action or an orderly shut- as a substitute for fuses or circuit breakers. down,thereby minimizing personnel hazard and equipment damage. II. Location. 240.13 Ground-Fault Protection of Equipment.Ground- 240.21 Location in Circuit. Overcurrent protection shall fault protection of equipment shall be provided in accor- be provided in each ungrounded circuit conductor and shall dance with the provisions of 230.95 for solidly grounded be located at the point where the conductors receive their wye electrical systems of more than 150 volts to ground but supply except as specified in 240.21(A)through (H). Conduc- not exceeding 600 volts phase-to-phase for each individual tors supplied under the provisions of 240.21(A) through (H) device used as a building or structure main disconnecting shall not supply another conductor except through an overcur- means rated 1000 amperes or more. rent protective device meeting the requirements of 240.4. The provisions of this section shall not apply to the disconnecting means for the following: (A) Branch-Circuit Conductors. Branch-circuit tap con- (1) Continuous industrial processes where a nonorderly shut- ductors meeting the requirements specified in 210.19 shall down will introduce additional or increased hazards be permitted to have overcurrent protection as specified in (2) Installations where ground-fault protection is provided 210.20. by other requirements for services or feeders (B) Feeder Taps. Conductors shall be permitted to be (3) Fire pumps tapped,without overcurrent protection at the tap,to a feeder as 70-86 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 240—OVERCURRENT PROTECTION 240.21 specified in 240.21(B)(1) through (13)(5). The provisions of value of the primary-to-secondary voltage ratio multi- 240.4(B) shall not be permitted for tap conductors. plied by one-third of the rating of the overcurrent de- (1) Taps Not over 3 m (10 ft) Long. Where the length of vice protecting the feeder conductors, the tap conductors does not exceed 3 m (10 ft) and the tap (3) The total length of one primary plus one secondary con- ductor, excluding any portion of the primary conductor conductors comply with all of the following: that is protected at its ampacity, is not over 7.5 in (25 ft). (1) The ampacity of the tap conductors is (4) The primary and secondary conductors are protected a. Not less than the combined calculated ]cads on the from physical damage by being enclosed in an ap- circuits supplied by the tap conductors, and proved raceway or by other approved means. b. Not less than the rating of the device supplied by the tap conductors or not less than the rating of the (5) The secondary conductors terminate in a single circuit overcurrent protective device at the termination of breaker or set of fuses that limit the load current to not the tap conductors. more than the conductor ampacity that is permitted by (2) The tap conductors do not extend beyond the switch- 310.15. board, panelboard, disconnecting means, or control de- (4) Taps over 7.5 m (25 ft)Long.Where the feeder is in a vices they supply. high bay manufacturing building over 11 m (35 ft) high at (3) Except at the point of connection to the feeder, the tap walls and the installation complies with all the following conductors are enclosed in a raceway, which shall ex- conditions: tend from the tap to the enclosure of an enclosed (1) Conditions of maintenance and supervision ensure that switchboard, panelboard, or control devices, or to the only qualified persons service the systems. back of an open switchboard. (2) The tap conductors are not over 7.5 m (25 ft) long (4) For field installations where the tap conductors leave horizontally and not over 30 m (100 ft) total length, the enclosure or vault in which the tap is made, the (3) The ampacity of the tap conductors is not less than rating of the overcurrent device on the line side of the one-third the rating of the overcurrent device protecting tap conductors shall not exceed 10 times the ampacity the feeder conductors. of the tap conductor. (4) The tap conductors terminate at a single circuit breaker FPN: For overcurrent protection requirements for panel- or a single set of fuses that limit the load to the ampac- boards, see 408.36. ity of the tap conductors. This single overcurrent de- (2) Taps Not over 7.5 m (25 ft)Long.Where the length of vice shall be permitted to supply any number of addi- the tap conductors does not exceed 7.5 m(25 ft) and the tap tional overcurrent devices on its load side. conductors comply with all the following: (5) The tap conductors are protected from physical damage (1) The ampacity of the tap conductors is not less than by being enclosed in an approved raceway or by other one-third of the rating of the overcurrent device pro- approved means. tecting the feeder conductors. (6) The tap conductors are continuous from end-to-end and (2) The tap conductors terminate in a single circuit breaker contain no splices. or a single set of fuses that limit the load to the ampac- (7) The tap conductors are sized 6 AWG copper or 4 AWG ity of the tap conductors.This device shall be permitted aluminum or larger, to supply any number of additional overcurrent devices (8) The tap conductors do not penetrate walls, floors, or on its load side. ceilings. (3) The tap conductors are protected from physical damage (9) The tap is made no less than 9 m (30 ft) from the floor. by being enclosed in an approved raceway or by other approved means. ($) Outside Taps of Unlimited Length. Where the con- ductors are located outdoors of a building or structure, ex- (3) Taps Supplying a Transformer [Primary Plus Sec- cept at the point of load termination,and comply with all of ondary Not over 7.5 m (25 ft) Long]. Where the tap con- the following conditions: ductors supply a transformer and comply with all the fol- (1) The conductors are protected from physical damage in lowing conditions: an approved manner. (1) The conductors supplying the primary of a transformer (2) The conductors terminate at a single circuit breaker or have an ampacity at least one-third the rating of the a single set of fuses that limit the load to the ampacity overcurrent device protecting the feeder conductors. of the conductors. This single overcurrent device shall (2) The conductors supplied by the secondary of the trans- be permitted to supply any number of additional over- former shall have an ampacity that is not less than the current devices on its load side. 2008 Edition NATIONAL ELECTRICAL CODE 70_87 240.21 ARTICLE 240--OVERCURRENT PROTECTION (3) The overcurrent device for the conductors is an integral (4) For field installations where the secondary conductors part of a disconnecting means or shall be located im- leave the enclosure or vault in which the supply con- mediately adjacent thereto. nection is made, the rating of the overcurrent device (4) The disconnecting means for the conductors is installed protecting the primary of the transformer,multiplied by at a readily accessible location complying with one of the primary to secondary transformer voltage ratio, the following: shall not exceed 10 times the ampacity of the second- a. Outside of a building or structure ary conductor. b. Inside, nearest the point of entrance of the conductors FPN: For overcurrent protection requirements for panel- c. Where installed in accordance with 230.6, nearest boards, see 40$.36. the point of entrance of the conductors (3) Industrial Installation Secondary Conductors Not (C) Transformer Secondary Conductors. A set of con- over 7.5 m (25 ft) Long, For industrial installations only, where the length of the secondary conductors does not ex- ceed 7.5 m (25 ft) and complies with all of the following: feeding separate loads, shall be permitted to be connected to a transformer secondary, without overcurrent protection {1) Conditions of maintenance and supervision ensure that at the secondary, as specified in 240.21(0)(1) through only qualified persons service the systems. (C)(6). The provisions of 240.4(B) shall not be permitted (2) The ampacity of the secondary conductors is not less for transformer secondary conductors. than the secondary current rating of the transformer, and the sum of the ratings of the overcurrent devices does FPN: For overcurrent protection requirements for trans- not exceed the ampacity of the secondary conductors, formers, see 450.3. (3) All overcurrent devices are grouped. (1) Protection by Primary Overcurrent Device.Conduc- (4) The secondary conductors are protected from physical tors supplied by the secondary side of a single-phase trans- damage by being enclosed in an approved raceway or former having a 2-wire (single-voltage) secondary, or a by other approved means. three-phase, delta-delta connected transformer having a 3-wire (single-voltage) secondary, shall be permitted to be {�} Outside secondary Conductors. Where the conduc- protecaed by overcurrent protection provided on the primary tors are located outdoors of a building or structure, except (supply) side of the transformer, provided this protection is in at the point of load termination, and comply with all of the accordance with 450.3 and does not exceed the value deter- fallowing conditions: mined by multiplying the secondary conductor ampacity by (1) The conductors are protected from physical damage in the secondary-to-primary transformer voltage ratio. an approved manner. Single-phase (other than 2-wire) and multiphase (other (2) The conductors terminate at a single circuit breaker or than delta-delta, 3-wire) transformer secondary conductors a single set of fuses that limit the load to the ampacity are not considered to be protected by the primary overcur- of the conductors. This single overcurrent device shall rent protective device. be permitted to supply any number of additional over- (2) Transformer Secondary Conductors Not over 3 m current devices on its load side. (10 ft) Long. Where the length of secondary conductor (3) The overcurrent device for the conductors is an integral does not exceed 3 m (10 ft) and complies with all of the part of a disconnecting means or shall be located im- following: mediately adjacent thereto. (I) The ampacity of the secondary conductors is (4) The disconnecting means for the conductors is installed at a readily accessible location complying with one of a. Not less than the combined calculated toads on the the following: circuits supplied by the secondary conductors, and b. Not less than the rating of the device supplied by a. Outside of a building or structure the secondary conductors or not less than the rating b. Inside, nearest the point of entrance of the conductors o c. Where installed in accordance with 230.6, nearest f the overcurrent-protective device at the termina- the point of entrance of the conductors tion of the secondary conductors (2) The secondary conductors do not extend beyond the (5) Secondary Conductors from a Feeder Tapped switchboard, panelboard, disconnecting means, or con- Transformer. Transformer secondary conductors installed trol devices they supply. in accordance with 240.21(B)(3) shall be permitted to have (3) The secondary conductors are enclosed in a raceway, overcurrent protection as specified in that section. which shall extend from the transformer to the enclo- (6) Secondary Conductors Not over 7.5 m (25 ft) Long. sure of an enclosed switchboard, panelboard,or control Where the length of secondary conductor does not exceed devices or to the back of an open switchboard. 7.5 m (25 ft) and complies with all of the following: 7048 NATIONAL ELECTRICAL CODE 2MH Edition ARTICLE 240—OVERCURRENT PROTECTION 240.24 (1) The secondary conductors shall have an ampacity that when in its highest position, is not more than 2.0 m(6 ft 7 in.) is not Iess than the value of the primary-to-secondary above the floor or working platform, unless one of the follow- voltage ratio multiplied by one-third of the rating of the ing applies: overcurrent device protecting the primary of the trans- (1) For busways, as provided in 368.17(C). former. (2) For supplementary overcurrent protection, as described (2) The secondary conductors terminate in a single circuit in 240.10. breaker or set of fuses that limit the load current to not more than the conductor ampacity that is permitted by (3) For overcurrent devices, as described in 225.40 and 310.15. 230.92. (3) The secondary conductors are protected from physical (4) For overcurrent devices adjacent to utilization equip- damage by being enclosed in an approved raceway or ment that they supply, access shall be permitted to be by other approved means, by portable means. (D) Service Conductors. Service conductors shall be per- (B) Occupancy. Each occupant shall have ready access to mitted to be protected by overcurrent devices in accordance all overcurrent devices protecting the conductors supplying with 230.91. that occupancy, unless otherwise permitted in 240.24(B)(1) (E) Busway Taps. Busways and busway taps shall be per- and (B)(2). mitted to be protected against overcurrent in accordance (1) Service and Feeder Overcurrent Devices. Where with 368.17. electric service and electrical maintenance are provided by (F) Motor Circuit Taps. Motor-feeder and branch-circuit the building management and where these are under continu- conductors shall be permitted to be protected against over- ous building management supervision,the service overcurrent current in accordance with 430.28 and 430.53,respectively. devices and feeder overcurrent devices supplying more than one occupancy shall be permitted to be accessible only to (G) Conductors from Generator Terminals. Conductors authorized management personnel in the following: from generator terminals that meet the size requirement in (1) Multiple-occupancy buildings 445.13 shall be permitted to be protected against overload (2) Guest rooms or guest suites by the generator overload protective device(s) required by 445.12. (2) Branch-Circuit Overcurrent Devices. Where electric service and electrical maintenance are provided by the (H) Battery Conductors. Overcurrent protection shall be service management and where these are under continu- perntitted to be installed as close as practicable to the stor- ous building management supervision, the branch-circuit age battery terminals in a non-hazardous location. Installa- tion of the overcurrent protection within a hazardous loca- overcurrent devices supplying any guest rooms or guest tion shall also be permitted. suites without permanent provisions for cooking shall be permitted to be accessible only to authorized management 240.22 Grounded Conductor.No overcurrent device shall personnel. be connected in series with any conductor that is intentionally grounded, unless one of the following two conditions is met: (C) Not Exposed to Physical Damage. Overcurrent de- (1) The overcurrent device opens all conductors of the cir- vices shall be located where they will not be exposed to cuit, including the grounded conductor, and is designed physical damage. so that no pole can operate independently. 1~PN: See 110.11. Deteriorating Agents. (2) Where required by 430.36 or 430.37 for motor over- load protection. (D) Not in Vicinity of Easily Ignitible Material.Overcur- rent devices shall not be located in the vicinity of easily 240.23 Change in Size of Grounded Conductor.Where a ignitible material, such as in clothes closets. change occurs in the size of the ungrounded conductor, a similar change shall be permitted to be made in the size of (E) Not Located in Bathrooms. In dwelling units and the grounded conductor. guest rooms or guest suites of hotels and motels, overcur- rent devices, other than supplementary overcurrent protec- 240.24 Location in or on Premises. tion, shall not be located in bathrooms. (A) Accessibility. Overcurrent devices shall be readily ac- cessible and shall be installed so that the center of the grip (F) Not Located over Steps.Overcurrent devices shall not of the operating handle of the switch or circuit breaker, be located over steps of a stairway. 2008 Edition NATIONAL ELECTRICAL CODE 70-89 240.30 ARTICLE 240—OVERCtiRRENT PROTECTION 111. Enclosures a way that persons in the vicinity are likely to be injured by 240.30 General. being struck by them, shall be guarded or isolated. (A) Protection from Physical Damage. Overcurrent de- V. Plug Fuses, Fuseholders, and Adapters vices shall be protected from physical damage by one of the following: 240.50 General. (1) Installation in enclosures, cabinets, cutout boxes, or (A) Maximum Voltage. Plug fuses shall be permitted to equipment assemblies be used in the following circuits: (2) Mounting on open-type switchboards, panelboards, or (1) Circuits not exceeding 125 volts between conductors control boards that are in rooms or enclosures free from dampness and easily ignitible material and are acces- (2) Circuits supplied by a system having a grounded neu- sible only to qualified personnel tral paint where the line-to-neutral voltage does not exceed 150 volts (B) Operating Handle. The operating handle of a circuit breaker shall be permitted to be accessible without opening ma Marking. Each fuse, fuseholder, and adapter shall be marked with its ampere rating. a door or cover. (C) Hexagonal Configuration. Plug fuses of 15-ampere 240.32 Damp or Wet Locations. Enclosures for overcur- and lower rating shall be identified by a hexagonal configu- rent devices in damp or wet locations shall comply with ration of the window, cap, or other prominent part to dis- 312.2• tinguish them from fuses of higher ampere ratings. 240.33 Vertical Position. Enclosures for overcurrent de- (D) No Energized Parts. Plug fuses, fuseholders, and vices shall be mounted in a vertical position unless that is adapters shall have no exposed energized parts after fuses shown to be impracticable.Circuit breaker enclosures shall be or fuses and adapters have been installed. permitted to be installed horizontally where the circuit breaker is installed in accordance with 240.81. Listed busway plug-in (E) Screw Shell.The screw shell of a plug-type fuseholder units shall be permitted to be mounted in orientations corre- shall be connected to the load side of the circuit. sponding to the busway mounting position. 240.51 Edison-Base Fuses. IV. Disconnecting and Guarding (A) Classification. Plug fuses of the Edison-base type shall be classified at not over 125 volts and 30 amperes and 240.40 Disconnecting Means for Fuses. Cartridge fuses below. in circuits of any voltage where accessible to other than qualified persons, and all fuses in circuits over 150 volts to (B) Replacement Only.Plug fuses of the Edison-base type ground, shall be provided with a disconnecting means on shall be used only for replacements in existing installations their supply side so that each circuit containing fuses can be where there is no evidence of overfusing or tampering. independently disconnected from the source of power. A current-limiting device without a disconnecting means shall 240.52 Edison-Base Fuseholders. Fuseholders of the be permitted on the supply side of the service disconnecting Edison-base type shall be installed only where they are means as permitted by 230.82. A single disconnecting made to accept Type S fuses by the use of adapters. means shall be permitted on the supply side of more than one set of fuses as permitted by 430.112, Exception, for 240.53 Type S Fuses. Type S fuses shall be of the plug group operation of motors and 424.22(C) for fixed electric type and shall comply with 240.53(A) and (13). space-heating equipment. (A) Classification. Type S fuses shall be classified at not 240.41 Arcing or Suddenly Moving Parts.Arcing or sud- over 125 volts and 0 to 15 amperes, 16 to 20 amperes, and denly moving parts shall comply with 240.41(A) and (B). 21 to 30 amperes. (A) Location. Fuses and circuit breakers shall be located (B) Noninterchangeable.Type S fuses of an ampere clas- or shielded so that persons will not be burned or otherwise sification as specified in 240.53(A) shall not be inter- injured by their operation. changeable with a lower ampere classification. They shall be designed so that they cannot be used in any fuseholder (B) Suddenly Moving Parts. Handles or levers of circuit other than a Type S fuseholder or a fuseholder with a Type breakers, and similar parts that may move suddenly in such S adapter inserted. 70-90 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 240—OVERCURRENT PROTECTION 240.85 240.54 Type S Fuses,Adapters, and Fuseholders. 240.61 Classification. Cartridge fuses and fuseholders shall be classified according to voltage and amperage {A) To Fit Edison-Base Fuseholders. Type S adapters ranges. Fuses rated 600 volts, nominal, or less shall be shall fit Edison-base fuseholders. permitted to be used for voltages at or below their ratings. (B) To Fit Type S Fuses Only. Type S fuseholders and adapters shall be designed so that either the fuseholder it- VII. Circuit Breakers self or the fuseholder with a Type S adapter inserted cannot be used for any fuse other than a Type S fuse. 240.80 Method of Operation. Circuit breakers shall be trip free and capable of being closed and opened by manual (C) Nonremovable. Type S adapters shall be designed so operation. Their normal method of operation by other than that once inserted in a fuseholder, they cannot be removed. manual means, such as electrical or pneumatic, shall be (D) Nontamperable.Type S fuses, fuseholders,and adapt- permitted if means for manual operation are also provided. ers shall be designed so that tampering or shunting (bridg- 240.81 indicating. Circuit breakers shall clearly indicate ing) would be difficult. whether they are in the open "off' or closed "on" position. (E) Interchangeability. Dimensions of Type S fuses, fuse- Where circuit breaker handles are operated vertically holders, and adapters shall be standardized to permit inter- rather than rotationally or horizontally, the "up" position of changeability regardless of the manufacturer. the handle shall be the "on" position. 240.82 Nontamperable. A circuit breaker shall be of such V1. Cartridge Fuses and Fuseholders design that any alteration of its trip point (calibration) or 240.60 General. the time required for its operation requires dismantling of the device or breaking of a seal for other than intended (A) Maximum Voltage—300-Volt Type. Cartridge fuses adjustments. and fuseholders of the 300-volt type shall be permitted to be used in the following circuits: 240.83 Marking. (I) Circuits not exceeding 300 volts between conductors (2) Single-phase line-to-neutral circuits supplied from a (A) Durable and Visible. Circuit breakers shall be marked with their ampere rating in a manner that will be durable 3-phase, 4-wire, solidly grounded neutral source where and visible after installation. Such marking shall be permit- the line-to-neutral voltage does not exceed 300 volts ted to be made visible by removal of a trim or cover. (B) Noninterchangeable — 0-6000-Ampere Cartridge (B) Location.Circuit breakers rated at 100 amperes or less Fuseholders. Fuseholders shall be designed so that it will and 600 volts or less shall have the ampere rating molded, be difficult to put a fuse of any given class into a fuseholder stamped, etched, or similarly marked into their handles or that is designed for a current lower, or voltage higher, than escutcheon areas. that of the class to which the fuse belongs. Fuseholders for current-limiting fuses shall not permit insertion of fuses (C) Interrupting Rating. Every circuit breaker having an that are not current-limiting. interrupting rating other than 5000 amperes shall have its (C) Marking. Fuses shall be plainly marked, either by interrupting rating shown on the circuit breaker. The inter- printing on the fuse barrel or by a label attached to the rupting rating shall not be required to be marked on circuit barrel showing the following: breakers used for supplementary protection. (1) Ampere rating (D) Used as Switches.Circuit breakers used as switches in (2) Voltage rating 120-volt and 277-volt fluorescent lighting circuits shall be (3) Interrupting rating where other than 10,000 amperes listed and shall be marked SWD or HID. Circuit breakers (4) Current limiting where applicable used as switches in high-intensity discharge lighting cir- (5) The name or trademark of the manufacturer cuits shall be listed and shall be marked as HID. The interrupting rating shall not be required to be (E) Voltage Marking. Circuit breakers shall be marked marked on fuses used for supplementary protection. with a voltage rating not less than the nominal system volt- age that is indicative of their capability to interrupt fault (D) Renewable Fuses. Class H cartridge fuses of the re- currents between phases or phase to ground. newable type shall be permitted to be used only for replace- ment in existing installations where there is no evidence of 240.85 Applications.A circuit breaker with a straight volt- overfusing or tampering. age rating, such as 240V or 480V, shall be permitted to be 2008 Edition NATIONAL ELECTRICAL CODE 70-91 240.86 ARTICLE 240—OVERCURRENT PROTECTION applied in a circuit in which the nominal voltage between VIII. Supervised Industrial Installations any two conductors does not exceed the circuit breaker's voltage rating. A two-pole circuit breaker shall not be used 240.90 General. Overcurrent protection in areas of super- for protecting a 3-phase, corner-grounded delta circuit un- vided industrial installations shall comply with all of the less the circuit breaker is marked 10-3 to indicate such other applicable provisions of this article, except as pro- suitability, vided in Part ViIi. The provisions of Part V111 shall he A circuit breaker with a slash rating, such as 120/240V permitted only to apply to those portions of the electrical or 480Y1277V, shall be permitted to be applied in a solidly system in the supervised industrial installation used exclu- grounded circuit where the nominal voltage of any conduc- sively for manufacturing or process control activities. for to ground does not exceed the lower of the two values of the circuit breaker's voltage rating and the nominal volt- 240.92 Location in Circuit. An overcurrent device shall age between any two conductors does not exceed the higher be connected in each ungrounded circuit conductor as re- value of the circuit breaker's voltage rating, quired in 240.92(A) through (E). FPN: Proper application of molded case circuit breakers on (A) Feeder and Branch-Circuit Conductors. Feeder and 3-phase systems, other than solidly grounded wye, particu- branch-circuit conductors shall be protected at the point the larly on corner grounded delta systems, considers the cir- cuit breakers' individual pole-interrupting capability. conductors receive their supply as permitted in 240.21 or as otherwise permitted in 240.92(13), (C), (D), or (E). 240.86 Series Ratings. Where a circuit breaker is used on a circuit having an available fault current higher than the (B) Feeder Taps. For feeder taps specified in 24O.21(B)(2), marked interrupting rating by being connected on the load (B)(3), and(13)(4),the tap Conductors shall be permitted to be side of an acceptable overcurrent protective device having a sized in accordance with Table 240.92(B). higher rating, the circuit breaker shall meet the require- ments specified in (A) or (B), and (C). (C) Transformer Secondary Conductors of Separately Derived Systems.Conductors shall be permitted to be con- (A) Selected Under Engineering Supervision in Existing netted to a transformer secondary of a separately derived Installations.The series rated combination devices shall be system, without overcurrent protection at the connection, selected by a licensed professional engineer engaged pri- where the conditions of 24092(C)(1), (C)(2), and (C)(3) marily in the design or maintenance of electrical installa- are met. tions. The selection shall be documented and stamped by the professional engineer. This documentation shall be (1) Short-Circuit and Ground-Fault Protection. The available to those authorized to design, install, inspect, conductors shall be protected from short-circuit and maintain, and operate the system. This series combination ground-fault conditions by complying with one of the fol- rating, including identification of the upstream device, shall lowing conditions: be field marked on the end use equipment. (1) The length of the secondary conductors does not ex- For calculated applications, the engineer shall ensure ceed 30 m (100 ft) and the transformer primary over- that the downstream circuit breaker(s) that are part of the current device has a rating or setting that does not ex- series Combination remain passive during the interruption ceed 150 percent of the value determined by period of the line side fully rated, current-limiting device, multiplying the secondary conductor ampacity by the (B) Tested Combinations. The combination of line-side secondary-to-primary transformer voltage ratio. overcurrent device and load-side circuit breaker(s) is tested (2) The conductors are protected by a differential relay and marked on the end use equipment, such as switch- with a trip setting equal to or less than the conductor boards and panelboards. ampacity. FPN to (A) and(B): See 110.22 for marking of series combi- FPN: A dilerential relay is connected to be sensitive only nation systems. to short-circuit or fault currents within the protected zone and is normally set much lower than the conductor ampac- (C) Motor Contribution. Series ratings shall not be used ity. The differential relay is connected to trip protective where devices that de-energize the protected conductors if a short- (1) Motors are connected on the load side of the higher- circuit condition occurs. rated overcurrent device and on the line side of the (3) The conductors shall be considered to be protected if lower-rated overcurrent device, and calculations, made under engineering supervision, de- (2) The sum of the motor full-load currents exceeds 1 per- termine that the system overcurrent devices will protect cent of the interrupting rating of the lower-rated circuit the conductors within recognized time vs.current limits breaker. for all short-circuit and ground-fault conditions. 70-92 NATIONAL,ELECTRICAL CODE 2(X)8 Edilion ARTICLE 240—OVERCURRENT PROTECTION 240.100 Table 240.92(B) Tap Conductor Short-Circuit Current (3) Overcurrent relaying is connected [with a current trans- Ratings. former(s), if needed] to sense all of the secondary con- ductor current and limit the load to the conductor am- Tap conductors are considered to be protected under pacity by opening upstream or downstream devices. short-circuit conditions when their short-circuit temperature limit is not exceeded. Conductor heating under short-circuit (4) Conductors shall be considered to be protected if cal- conditions is determined by (1) or(2): culations, made under engineering supervision, deter- mine that the system overcurrent devices will protect (1)Short-Circuit Formula for Capper Conductors the conductors from overload conditions. WIA')t=0.0297 log,,, 1(T2 + 234)1(T, + 234)1 (3) Physical Protection. The secondary conductors are (2) Short-Circuit Formula for Aluminum Conductors protected from physical damage by being enclosed in an approved raceway or by other approved means. (121A2)t=0.0125 log,,, 1(71, + 228)/(T, + 228)1 where: (D) Outside Feeder Taps. Outside conductors shall be per- mitted to be tapped to a feeder or to be connected at a trans- I=short-circuit current in amperes former secondary, without overcurrent protection at the tap or connection, where all the following conditions are met: A =conductor area in circular mils (1) The conductors are protected from physical damage in t= time of short circuit in seconds (for times less than or equal an approved manner. to 10 seconds) (2) The sum of the overcurrent devices at the conductor T, = initial conductor temperature in degrees Celsius. termination limits the load to the conductor ampacity. The overcurrent devices shall consist of not more than T, = final conductor temperature in degrees Celsius. six circuit breakers or sets of fuses mounted in a single enclosure, in a group of separate enclosures,or in or on Copper conductor with paper, rubber, varnished cloth insulation, a switchboard. There shall be no more than six over- Ty = 200 current devices grouped in any one location. Copper conductor with thermoplastic insulation, T, = 150 (3) The tap conductors are installed outdoors of a building Copper conductor with cross-linked polyethylene insulation, TZ or structure except at the point of load termination. = 250 (4) The overcurrent device for the conductors is an integral pan of a disconnecting means or shall be Iocated im- Copper conductor with ethylene propylene rubber insulation, TZ mediately adjacent thereto. = 250 (5) The disconnecting means for the conductors are in- Aluminum conductor with paper, rubber, varnished cloth stalled at a readily accessible location complying with insulation, T2 = 200 one of the following: Aluminum conductor with thermoplastic insulation, Tz = 150 a. Outside of a building or structure b. Inside, nearest the point of entrance of the conductors Aluminum conductor with cross-linked polyethylene insulation, c. Where installed in accordance with 230.6, nearest Tz = 250 the point of entrance of the conductors Aluminum conductor with ethylene propylene rubber insulation, (E) Protection by Primary Overcurrent Device. Con- r, =250 ductors supplied by the secondary side of a transformer shall be permitted to be protected by overcurrent protection (2) Overload Protection. The conductors shall be pro- provided on the primary (supply) side of the transformer, of the t against overload conditions by complying with one provided the primary device time–current protection char- acteristic,following: acteristic, multiplied by the maximum effective primary-to- (1) The conductors terminate in a single overcurrent device secondary transformer voltage ratio,effectively protects the that will limit the load to the conductor ampacity. secondary conductors. (2) The sum of the overcurrent devices at the conductor termination limits the load to the conductor ampacity. The overcurrent devices shall consist of not more than IX. Overcurrent Protection over 600 Volts, Nominal six circuit breakers or sets of fuses, mounted in a single 240.100 Feeders and Branch Circuits. enclosure, in a group of separate enclosures,or in or on a switchboard. There shall be no more than six over- (A) Location and Type of Protection.Feeder and branch- current devices grouped in any one location. circuit conductors shall have overcurrent protection in each 2008 Edition NATIONAL ELECTRICAL CODE 70-93 240.101 ARTICLE 250—GROUNDING AND BONDING ungrounded conductor located at the point where the con- ductor receives its supply or at an alternative location in the ARTICLE 250 circuit when designed under engineering supervision that Grounding and Banding includes but is not limited to considering the appropriate fault studies and time—current coordination analysis of the protective devices and the conductor damage curves. The 1. General overcurrent protection shall be permitted to be provided by either 240.100(A)(I) or (A)(2). 250.1 Scope. This article covers general requirements for grounding and bonding of electrical installations, and the (1) Overcurrent Relays and Current Transformers.Cir- specific requirements in (1) through (6). cuit breakers used for overcurrent protection of 3-phase (1) Systems, circuits, and equipment required, permitted, circuits shall have a minimum of three overcurrent relay or not permitted to be grounded elements operated from three current transformers. The separate overcurrent relay elements (or protective func- (2) Circuit conductor to be grounded on grounded systems tions) shall be permitted to be part of a single electronic (3) Location of grounding connections protective relay unit. (4) Types and sizes of grounding and bonding conductors On 3-phase, 3-wire circuits, an overcurrent relay ele- and electrodes ment in the residual circuit of the current transformers shall (5) Methods of grounding and bonding be permitted to replace one of the phase relay elements. An overcurrent relay element, operated from a current (6) Conditions under which guards, isolation, or insulation transformer that links all phases of a 3-phase, 3-wire cir- may be substituted for grounding cuit, shall be permitted to replace the residual relay element FPN: See Figure 250.1 For information on the organiza- and one of the phase-conductor current transformers. tion of Article 250 covering grounding and bonding Where the neutral conductor is not regrounded on the load requirements. side of the circuit as permitted in 250.184(B), the current transformer shall be permitted to link all 3-phase conduc- tors and the grounded circuit conductor (neutral). Part I General (2) Fuses. A fuse shall be connected in series with each ungrounded conductor. Part II system grounding (B) Protective Devices. The protective device(s) shall be ————————— —— capable of detecting and interrupting all values of current Part Vol Direct-current that can occur at their location in excess of their trip-setting systems — or melting point, Part X Grounding of systems and circuits of (C) Conductor Protection.The operating time of the pro- I 1 kV and over(high voltage) tective device, the available short-circuit current, and the conductor used shall be coordinated to prevent damaging or Part Ili Grounding electrode dangerous temperatures in conductors or conductor insula- system and grounding Part V Bonding lion under short-circuit conditions, electrode conductor Part IV Enclosure, 240.101 Additional Requirements for Feeders. raceway,and service (A) Rating or Setting of Overcurrent Protective De- cable grounding vices. The continuous ampere rating of a fuse shall not riVlEquipment exceed three times the ampacity of the conductors. The Fgr7on ng and equipment long-time trip element setting of a breaker or the minimum grounding conductors trip setting of an electronically actuated fuse shall not ex- ceed six times the ampacity of the conductor. For fire Part VII Methods of pumps, conductors shall be permitted to be protected for equipment grounding overcurrent in accordance with 695.4(B). (B) Feeder Taps. Conductors tapped to a feeder shall be Part IX Instruments, permitted to be protected by the feeder overcurrent de- meters,and relays vice where that overcurrent device also protects the tap conductor. Figure 250.1 Grounding and Bonding. 70-94 NATIONAL ELECTRICAL CODE 20078 Edition ARTICLE 250—GROUNDING AND BONDING 250.4 250.2 Definitions. (2) Grounding of Electrical Equipment. Normally non— Bonding Jumper, System. The connection between the current-carrying conductive materials enclosing electrical conductors or equipment, or forming part of such equip- grounded circuit conductor and the equipment grounding ment, shall be connected to earth so as to limit the voltage conductor at a separately derived system. to ground on these materials. Effective Ground-Fault Current Path. An intentionally constructed, low-impedance electrically conductive path (3) Bonding of Electrical Equipment. Normally non— constructed, conductive materials enclosing electrical designed and intended to carry current under ground-fault conditions from the point of a ground fault on a wiring system conductors or equipment, or farming part of such equip- to the electrical supply source and that facilitates the operation ment, shall be connected together and to the electrical sup- of the overcurrent protective device or ground-fault detectors source in a manner that establishes an effective ground- of high-impedance grounded systems. fault current path. Ground Fault. An unintentional, electrically conducting (4) Bonding of Electrically Conductive Materials and connection between an ungrounded conductor of an electri- Other Equipment. Normally non—current-carrying elec- cal circuit and the normally non—current-carrying conduc- trically conductive materials that are likely to become tors, metallic enclosures, metallic raceways, metallic equip- energized shall be connected together and to the electri- ment, or earth. cal supply source in a manner that establishes an effec- tive ground-fault current path. Ground-Fault Current Path. An electrically conductive path from the point of a ground fault on a wiring system (5) Effective Ground-Fault Current Path. Electrical through normally non-current-carrying conductors, equip- equipment and wiring and other electrically conductive ma- ment, or the earth to the electrical supply source. terial likely to become energized shall be installed in a manner that creates a low-impedance circuit facilitating the FPN: Examples of ground-fault current paths could consist operation of the overcurrent device or ground detector for of any combination of equipment grounding conductors, high-impedance grounded systems. It shall be capable of metallic raceways, metallic cable sheaths, electrical equip- safely carrying the maximum ground-fault current likely to ment,and any other electrically conductive material such as metal water and gas piping, steel framing members, stucco be imposed on it from any point on the wiring system mesh, metal ducting, reinforcing steel, shields of commu- where a ground fault may occur to the electrical supply nications cables, and the earth itself, source. The earth shall not be considered as an effective ground-fault current path. 250.3 Application of Other Articles. For other articles applying to particular cases of installation of conductors (B) Ungrounded Systems. and equipment, grounding and bonding requirements are identified in Table 250.3 that are in addition to, or modifi- (1) Grounding Electrical Equipment. Non—current- identified of, those of this article. carrying conductive materials enclosing electrical conduc- tors or equipment, or farming part of such equipment, shall 250.4 General Requirements for Grounding and Bond- be connected to earth in a manner that will limit the ing. The fallowing general requirements identify what voltage imposed by lightning or unintentional contact grounding and bonding of electrical systems are required to with higher-voltage lines and limit the voltage to ground accomplish. The prescriptive methods contained in Article on these materials. 250 shall be followed to comply with the performance re- (2) Bonding of Electrical Equipment. Non—current- quirements of this section. carrying conductive materials enclosing electrical conduc- (A) Grounded Systems. tors or equipment, or forming part of such equipment,shall be connected together and to the supply system grounded (1) Electrical System Grounding. Electrical systems that equipment in a manner that creates a low-impedance path are grounded shall be connected to earth in a manner that for ground-fault current that is capable of carrying the will limit the voltage imposed by lightning, line surges, or maximum fault current likely to be imposed on it, unintentional contact with higher-voltage lines and that will stabilize the voltage to earth during normal operation. (3) Bonding of Electrically Conductive Materials and Other Equipment. Electrically conductive materials that FFN: An important consideration for limiting the imposed are likely to become energized shall be connected together voltage is the routing of bonding and grounding conductors and to the supply system grounded equipment in a manner so that they are not any longer than necessary to complete that creates a low-impedance path for ground-fault current the connection without disturbing the permanent parts of the installation and so that unnecessary bends and loops are that is capable of carrying the maximum fault current likely avoided. to be imposed on it. 2009 Edition NATIONAL ELECTRICAL CODE 70-95 250.4 ARTICLE 250—GROUNDING AND BONDING Table 250.3 Additional Grounding and Bonding Requirements Conductor/Equipment Article Section Agricultural buildings 547.9 and 547.10 Audio signal processing, amplification, and 640.7 reproduction equipment Branch circuits 210.5, 210.6,406.3 Cablebus 370,9 Cable trays 392 392.3(0), 392.7 Capacitors 460.10, 460.27 Circuits and equipment operating at less than 50 720 volts Communications circuits 800 Community antenna television and radio distribution 820.93, 820.100, 820.103 systems Conductors for general wiring 310 Cranes and hoists 610 Electrically driven or controlled irrigation machines 675.11(C), 675,12, 675.13, 675.14, 675.15 Electric signs and outline lighting 600 Electrolytic cells 668 Elevators, dumbwaiters, escalators, moving walks, 620 wheelchair lifts, and stairway chairlifts Fixed electric heating equipment for pipelines and 427 29, 427.48 vessels Fixed outdoor electric deicing and snow-melting 426.27 equipment Flexible cords and cables 400.22,400.23 Floating buildings 553.8,553.10, 553.11 Grounding-type receptacles, adapters, cord 406,9 connectors, and attachment plugs Hazardous (classified) locations 500-517 Health care facilities 517 Induction and dielectric heating equipment 665 Industrial machinery 670 Information technology equipment 645.15 Intrinsically safe systems 504.50 Luminaires and lighting equipment 410.40,410.42,410.46, 410.155(B) Luminaires, lampholders, and lamps 410 Marinas and boatyards 555.15 Mobile homes and mobile home park 550 Motion picture and television studios and similar 530.20,530.64(B) locations Motors, motor circuits, and controllers 430 Natural and artificially made bodies of water 682 682,30,682.31, 682.32, 682.33 Outlet, device, pull, and junction boxes; conduit 314.4, 314.25 bodies; and fittings Over 600 volts, nominal, underground wiring 300.50(B) methods Panelboards 408.40 Pipe organs 650 Radio and television equipment 810 Receptacles and cord connectors 406.3 Recreational vehicles and recreational vehicle parks 551 Services 230 Solar photovoltaic systems 690.41, 690.42, 690.43, 690.45, 690.47 Swimming pools, fountains, and similar installations 680 Switchboards and panelboards 408.3(D) Switches 404,12 Theaters, audience areas of motion picture and 520.81 television studios, and similar locations Transformers and transformer vaults 450.10 Use and identification of grounded conductors 200 X-ray equipment 660 517.78 70--96 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 250—GROUNDING AND BONDING 250.20 (4) Path for Fault Current, Electrical equipment, wiring, 250.8 Connection of Grounding and Bonding and other electrically conductive material likely to become Equipment. energized shall be installed in a manner that creates a low- impedance circuit from any paint on the wiring system to (A) Permitted Methods. Grounding conductors and bond- the electrical supply source to facilitate the operation of tog jumpers shall be connected by one of the following means: overcurrent devices should a second ground fault from a different phase occur on the wiring system. The earth shall (l) Listed pressure connectors not be considered as an effective fault-current path. (2) Terminal bars (3) Pressure connectors listed as grounding and bonding equipment 250.6 Objectionable Current. (4) Exothermic welding process (A) Arrangement to Prevent Objectionable Current. (5) Machine screw-type fasteners that engage not less than The grounding of electrical systems, circuit conductors, two threads or are secured with a nut surge arresters, surge-protective devices, and conductive (6) Thread-Forming machine screws that engage not less normally non-current-carrying metal parts of equipment than two threads in the enclosure shall be installed and arranged in a manner that will prevent (7) Connections that are part of a listed assembly objectionable current. (8) Other listed means (B) Alterations to Stop Objectionable Current. If the (B) Methods Not Permitted. Connection devices or fit- use of multiple grounding connections results in objection- tings that depend solely on solder shall not be used. able current, one or more of the following alterations shall be permitted to be made, provided that the requirements of 250.10 Protection of Ground Clamps and Fittings. 250.4(A)(5) or (13)(4) are met: Ground clamps or other fittings shall be approved for gen- (1) Discontinue one or more but not all of such grounding eral use without protection or shall be protected from connections. physical damage as indicated in (1) or (2) as follows: (2) Change the locations of the grounding connections. (1) In installations where they are not likely to be damaged (3) Interrupt the continuity of the conductor or conductive (2) Where enclosed in metal, wood, or equivalent protec- path causing the objectionable current. tive covering (4) Take other suitable remedial and approved action. 250.12 Clean Surfaces. Nonconductive coatings (such as paint, lacquer, and enamel) on equipment to be grounded (C) Temporary Currents Not Classified as Objection- shall be removed from threads and other contact surfaces able Currents. Temporary currents resulting from acciden- to ensure good electrical continuity or be connected by tal conditions, such as ground faults, shall not be classified means of fittings designed so as to make such removal as objectionable current for the purposes specified in unnecessary. 250.6(A) and (B). (D) Limitations to Permissible Alterations. The provi- H. System Grounding sions of this section shall not be considered as permitting 250.20 Alternating-Current Systems to Be Grounded. electronic equipment from being operated on ac systems or Alternating-current systems shall be grounded as provided branch circuits that are not connected to an equipment for in 250.20(A), (B), (C), (D), or(E). Other systems shall grounding conductor as required by this article. Currents be permitted to be grounded. If such systems are grounded, that introduce noise or data errors in electronic equipment they shall comply with the applicable provisions of this shall not be considered the objectionable currents addressed article. in this section. FPN: An example of a system permitted to be grounded is (E) isolation of Objectionable Direct-Current Ground a corner-grounded delta transformer connection. See 250.26{4) l�n•conductor to be grounded. Currents. Where isolation of objectionable do ground cur- rents from cathodic protection systems is required, a listed (A) Alternating-Current Systems of Less Than 50 Volts. ac coupling/dc isolating device shall be permitted in the Alternating-current systems of less than 50 volts shall be equipment grounding conductor path to provide an efec- grounded under any of the following conditions: tive return path for ac ground-fault current while blocking (1) Where supplied by transformers,if the transformer sup- dc current. ply system exceeds 150 volts to ground 2008 Edition NATIONAL ELECTRICAL CODE 70-97 250.21 ARTICLE 250--GROUNDING AND BONDING (2) Where supplied by transformers,if the transformer sup- (2) Separately derived systems used exclusively for recti- ply system is ungrounded fiers that supply only adjustable-speed industrial drives (3) Where installed outside as overhead conductors (3) Separately derived systems supplied by transformers (B) Alternating-Current Systems of 50 Volts to 1000 that have a primary voltage rating less than 1000 volts, Volts. Alternating-current systems of 50 volts to 1000 volts provided that all the following conditions are met: that supply premises wiring and premises wiring systems a. The system is used exclusively for control circuits. shall be grounded under any of the following conditions: b. The conditions of maintenance and supervision (1) Where the system can be grounded so that the maxi- ensure that only qualified persons service the in- mum voltage to ground on the ungrounded conductors stallation. does not exceed 150 volts c. Continuity of control power is required. (2) Where the system is 3-phase, 4-wire, wye connected in (4) Other systems that are not required to be grounded in which the neutral conductor is used as a circuit conductor accordance with the requirements of 250.20(B) (3) Where the system is 3-phase,4-wire,delta connected in (g) Ground Detectors. Ungrounded alternating current which the midpoint of one phase winding is used as a circuit conductor systems as Permitted in 250.21(A)(1) through (A)(4) oper- ating at not less than 120 volts and not exceeding 1000 (C) Alternating-Current Systems of I kV and Over. volts shall have ground detectors installed on the system. Alternating-current systems supplying mobile or portable equipment shall be grounded as specified in 250.188. 250.22 Circuits Not to Be Grounded. The following cir- Where supplying other than mobile or portable equipment, cuits shall not be grounded: such systems shall be permitted to be grounded. (1) Circuits for electric cranes operating over combustible (D) Separately Derived Systems. Separately derived sys- fibers in Class III locations, as provided in 503.155 tems, as covered in 250.20(A) or(B), shall be grounded as (2) Circuits in health care facilities as provided in 517.61 specified in 250.30(A). Where an alternate Source such as and 517.160 an on-site generator is provided with transfer equipment (3) Circuits for equipment within electrolytic cell working that includes a grounded conductor that is not solidly inter- zone as provided in Article 668 connected to the service-Supplied grounded conductor, the (4) Secondary circuits of lighting systems as provided in alternate Source (derived system) shall be grounded in ac- 411.5(A) cordance with 250.30(A). (5) Secondary circuits of lighting systems as provided in FPN No. l: An alternate ac power source such as an on- 680.23(A)(2). site generator is not a separately derived system if the grounded conductor is solidly interconnected to a service- supplied system grounded conductor.An example of such 250.24 Grounding Service-Supplied Alternating-Current situations is where alternate source transfer equipment does Systems. not include a switching action in the grounded conductor and allows it to remain solidly connected to the service- (A) System Grounding Connections. A premises wiring supplied grounded conductor when the alternate source is system supplied by a grounded ac service shall have a operational and supplying the load served. grounding electrode conductor connected to the grounded FPN No.2: For systems that are not separately derived and service conductor, at each service, in accordance with are not required to be grounded as specified in 250.30, see 250.24(A)(1) through (A)(5). 445.13 for minimum size of conductors that must carry fault current. (1) General. The grounding electrode conductor connec- (E) Impedance Grounded Neutral Systems. Impedance tion shall be made at any accessible point from the load end grounded neutral systems shall be grounded in accordance of the service drop or service lateral to and including the with 250.36 or 250.186. terminal or bus to which the grounded service conductor is 250.21 Alternating-Current Systems of 50 Volts to 1000 connected at the service disconnecting means. Volts Not Required to Be Grounded. FPN: See definitions of Service Drop and Service Lateral in Article 100. (A) General.The following ac systems of 50 volts to 1000 volts shall be permitted to be grounded but shall not be (2) Outdoor Transformer. Where the transformer supply- required to be grounded: ing the service is located outside the building, at least one (1) Electrical systems used exclusively to supply industrial additional grounding connection shall be made from the electric furnaces for melting, refining, tempering, and grounded service conductor to a grounding electrode, either the like at the transformer or elsewhere outside the building. 70-98 NATIONAL ELFMICAL CODE 2008 Edition ARTICLE 250—GROUNDING AND BONDING 250.24 Exception: The additional grounding electrode conductor Exception: Where more than one service disconnecting connection shall not be made on high-impedance grounded means are located in a single assembl listed for use as neutral s}•sterns. The s_�•stem shall meet the requirements oj' service equipment, it shall be permitted to run the grounded 250.36. conductor(s) to the assembl}• common grounded conduc- (3) Dual-Fed Services. For services that are dual fed tor(s) terminal or bus. The assembly shall include a main (double ended) in a common enclosure or grouped together bonding jumper for connecting the grounded conductor(s) to the assenibl• enclosure. in separate enclosures and employing a secondary tie, a single grounding electrode conductor connection to the tie (1) Routing and Sizing. This conductor shall be routed point of the grounded conductor(s) from each power source with the phase conductors and shall not be smaller than the shall be permitted. required grounding electrode conductor specified in Table 250.66 but shall not be required to be larger than the largest {4) Main Bonding Jumper as Wire or Busbar.Where the ungrounded service-entrance phase conductor. In addition, main bonding jumper specified in 250.28 is a wire or bus- bar and is installed from the grounded conductor terminal for service-entrance phase conductors larger than 1100 ke- mil copper or 1750 kcmil aluminum, the grounded conduc- in the service equipment, the grounding electrode conduc- bar or bus to the equipment grounding terminal bar or bus for shalt not be smaller than 12'/2 percent of the area of the largest service-entrance phase conductor. The grounded for shall be permitted to be connected to the equipment conductor of a 3-phase, 3-wire delta service shall have an grounding terminal, bar, or bus to which the main banding jumper is connected. ampacity not less than that of the ungrounded conductors. (5) Load-Side Grounding Connections. A grounded con- (2) .Parallel Conductors. Where the service-entrance phase conductors are installed in parallel, the size of the grounded ductor shall not be connected to normally non—current- conductor shall be based on the total circular trail area of the carrying metal parts of equipment, to equipment grounding parallel conductors as indicated in this section. Where in- conductor(s), or be reconnected to ground on the load side stalled in two or more raceways, the size of the grounded of the service disconnecting means except as otherwise per- conductor in each raceway shall be based on the size of the mitted in this article. ungrounded service-entrance conductor in the raceway but not FPN: See 250.30(A) for separately derived systems, smaller than 1/0 AWG. 250.32 for connections at separate buildings or structures, and 250.142 for use of the grounded circuit conductor for FPN: See 310.4 for grounded conductors connected in grounding equipment, parallel. (B) Main Bonding Jumper. For a grounded system, an (3) High Impedance. The grounded conductor on a high- unspliced main bonding jumper shall be used to connect the impedance grounded neutral system shall be grounded in equipment grounding conductor(s) and the service- accordance with 250.36. disconnect enclosure to the grounded conductor within the (D) Grounding Electrode Conductor. A grounding elec- enclosure for each service disconnect in accordance with trode conductor shall be used to connect the equipment 250.28. grounding conductors, the service-equipment enclosures, Exception No. 1: Where snore than one service disconnect- and, where the system is grounded, the grounded service ing means is located in an as.senibl listed for use as ser- conductor to the grounding electrode(s) required by Part III ut vice equipment, c unspliced main bonding jumper shall of this article. This conductor shall be sized in accordance bond the grounded conductor(s) to the assembl• enclosure. with 250.66. High-impedance grounded neutral system connections Exception No. 2: lmpedcnu e grounded neutral systems shall be made as covered in 250.36. shall be permitted to be connected cis provided in 250.36 and 250.1116. FPN: See 250.24(A) for ac system grounding connections. (C) Grounded Conductor Brought to Service Equip- (E) Ungrounded System Grounding Connections.A pre- ment.Where an ac system operating at less than 1000 volts mises wiring system that is supplied by an ac service that is is grounded at any point, the grounded conductor(s) shall ungrounded shall have, at each service, a grounding elec- be run to each service disconnecting means and shall be trode conductor connected to the grounding electrode(s) connected to each disconnecting means grounded conduc- required by Part III of this article.The grounding electrode tor(s)terminal or bus.A main bonding jumper shall connect conductor shall be connected to a metal enclosure of the the grounded conductor(s) to each service disconnecting service conductors at any accessible point from the load means enclosure. The grounded conductor(s) shall be in- end of the service drop or service lateral to the service stalled in accordance with 250.24(C)(1) through (C)(3). disconnecting means. 2008 Edition NATIONAL ELECTRICAL CODE 70-99 250.26 ARTICLE 250--GROUNDING AND BONDING 250.26 Conductor to Be Grounded—Alternating-Current more than a Single enclosure, the system bonding jumper Systems. For ac premises wiring systems, the conductor to for each enclosure shall be sized in accordance with be grounded shall be as specified in the following: 250.28(D)(1) based on the largest ungrounded feeder con- (1) Single-phase, 2-wire — one conductor ductor Serving that enclosure, or a single System bonding (2) Single-phase, 3-wire — the neutral conductor jumper shall be installed at the source and sized in accor- dance with 250.28(D)(1)based on the equivalent size of the (3) Multiphase systems having one wire common to all largest supply conductor determined by the largest sum of phases — the common conductor (4) Multiphase systems where one phase is grounded the areas of the corresponding conductors of each set. — one phase conductor 250.30 Grounding Separately Derived Alternating- (5) Multiphase systems in which one phase is used as in Current Systems. (2) —the neutral conductor (A) Grounded Systems. A separately derived ac system 250.28 Main Bonding Jumper and System Bonding that is grounded shall comply with 250.30(A)(1) through Jumper. For a grounded system, main bonding jumpers (A)(8). Except as otherwise permitted in this article, a and system bonding jumpers shall be installed as follows: Founded conductor shalt not be connected to normally noncurrent-carrying metal parts of equipment, to equip- (A) Material. Main bonding jumpers and system bonding ment grounding conductors,or be reconnected to ground on jumpers shall be of copper or other corrosion-resistant ma- the load side of the point of grounding of a separately terial. A main bonding jumper and a system bonding jumper derived system. shall be a wire, bus, screw, or similar suitable conductor. FPN: See 250.32 for connections at separate buildings or (B) Construction. Where a main bonding jumper or a sys- structures,and 250.142 for use of the grounded circuit con- ductor for grounding equipment. tem bonding jumper is a screw only, the screw shall be identified with a green finish that shall be visible with the Exception: Impedance grounded neutral system grounding screw installed. connections shall be made as specified in 250.36 or 250.186. (C) Attachment. Main bonding jumpers and system bond- ing jumpers shall be connected in the manner specified by (1) System Bonding Jumper. An unspliced system bond- the applicable provisions of 250.8. ing jumper in compliance with 250.28(A) through (D) that is sized based on the derived phase conductors shall be (D) Size. Main bonding jumpers and system bonding used to connect the equipment grounding conductors of the jumpers shall be Sized in accordance with 250.28(D)(1) separately derived system to the grounded conductor. This through (D)(3). connection shall be made at any single point on the sepa- rately derived system from the source to the first system (1} General. Main bonding jumpers and system bonding disconnecting means or overcurrent device, or it shall be jumpers shall not be smaller than the sizes shown in made at the source of a separately derived system that has Table 250.66. Where the supply conductors are larger no disconnecting means or overcurrent devices. than 1100 kemil copper or 1750 kcmil aluminum, the bonding jumper shall have an area that is not less than Exceptive No. 1: For separately derived systems that are 121/2 percent of the area of the largest phase conductor dual fed(double ended) in a common enclosure or grouped separate enclosures and employing a secondary together i except that, where the phase conductors and the bonding lie,tie, a single system bonding jumper connection to the tie jumper are of different materials (copper or aluminum), point of the grounded circuit conductors from each power the minimum size of the bonding jumper shall be based on the assumed use of phase conductors of the same source shall be permitted. material as the bonding jumper and with an ampacity Exception No. 2: A system bonding jumper at both the equivalent to that of the installed phase conductors. source and the first disconnecting means shall be permitted where doing so does not establish a parallel path for the (2) Main Bonding Jumper for Service with More Than grounded conductor. Where a grounded conductor is used One Enclosure. Where a service consists of more than a in this manner, it shall not be.smaller than the size specified single enclosure as permitted in 230.71(A),the main bond- for the system bonding jumper but shall not be required to ing jumper for each enclosure shall be sized in accordance be larger than the ungrounded conductor(s). For the pur- with 25028(D)(1)based on the largest ungrounded service poses of this exception, connection through the earth shall conductor serving that enclosure, not be considered as providing a parallel path. (3) Separately Derived System. with More Than One Exception No. 3: The size of the system.bonding jumper for Enclosure. Where a separately derived system supplies a system that supplies a Class 1, Class 2, or Class 3 70-100 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 250—GROUNDING AND BONDING 250.30 cinuit, and is derived from a transformer rated not more than rived system to the common grounding electrode conduc- 1000 volt-amperes, shall not he smaller than the derived tor. The grounding electrode conductors and taps shall phase conductors and shall not he smaller than 14 AWG cop- comply with 250,30(A)(4)(a) through (A)(4)(c). This con- per or 12 AWG ahuninum. nection shall be made at the same point on the separately (2) Equipment Bonding Jumper Size. Where an equip- derived system where the system bonding jumper is in- ment bonding jumper of the wire type is run with the de- stalled. rived phase conductors from the source of a separately de- Exception No. 1: Where the system bonding jumper spec•i- rived system to the first disconnecting means, it shall be fled in 250.30(A)(1) is a wire or busbar, it shall he permit- sized in accordance with 250.102(C), based on the size of ted to connect the grounding electrode conductor to the the derived phase conductors. equipment grounding terminal, bar, or bus, provided the equipment grounding terminal, bar,, or bus is of'suftcient (3) Grounding Electrode Conductor, Single Separately size for the separately derived system. Derived System. A grounding electrode conductor for a single separately derived system shall be sized in accor- Exception No. 2: A grounding electrode conductor shall dance with 250.66 for the derived phase conductors and not be required for a s_ystenn that supplies a Class 1, Class shall be used to connect the grounded conductor of the 2, or Class 3 circuit and is derived from a transformer derived system to the grounding electrode as specified in rated not more than 1000 volt-amperes, provided the sys- tern grounded conductor is bonded to the trans orner 250.30(A)(7). This connection shall be made at the same fi•anre or enclosure br a jumper sized m accordance with point on the separately derived system where the system 250.30(A)(I), Exception No. 3 cued the transformer frame bonding jumper is connected, or enclosure is grounded by one of the means specified in Exception No. 1: Where the system bonding jumper speci- 250.134. fled in 250.30(A)(1) is a wire or busbar, it shall be pernit- ted to connect the grounding electrode conductor to the (a) Common Grounding Electrode Conductor Size. equipment grounding terminal, bar, or hits, provided the The common grounding electrode conductor shall not be equipment grounding terminal, bar, or bus is of sufficient smaller than 310 AWG copper or 250 kcmil aluminum. size for the separately derived systenn. (b) Tap Conductor Size. Each tap conductor shall be Exception No. 2: Where a separately derived system origi- sized in accordance with 250.66 based on the derived phase nates in listed equipment suitable us service equipment, the conductors of the separately derived system it serves. grounding electrode conductor from the service or feeder Exception: Where a separately derived system originates equipment to the grounding electrode shall he permitted as in listed equipment .suitable as service equipment, the the grounding electrode conductor for the separately de- grounding electrode conductor fronn the service or feeder rived system,provided the grounding electrode conductor is equipment to the,]grounding electrode shall be permitted as of sufficient size for the separately derived system. Where the grounding electrode conductor for the .separately de - the equipment grounding bits internal to the equipment is rived s;ystent,provided the grounding electrode conductor is not smaller than the required grounding electrode conduc•- of sufficient size for the separately derived ,system. Where for for the separately derived system, the grounding elec- the equipment ground buts internal to the equipment is not trode connection for the separatel}•derived systenn.shall be smaller than the required grounding electrode conductor permitted to he made to the baits. for the separately derived systent, the grounding electrode Exception No. 3: A grounding electrode conductor shall connection for the separately derived system shall be per- not be required for a sve stn that supplies a Class 1, Class inmtted to be Horde to the buts. 2, or Class 3 circuit annd is derived from a transformer (c) Connections. All tap connections to the common rated not more than 1000 volt-amperes, provided the grounding electrode conductor shall be made at an acces- grounded conductor is bonded to the transformer frame me or sible location by one of the following methods; enclosure b}• a jumper sized in accordance with (1) A listed connector. 250.30(A)(1), Exception No. 3, and the transformer frame (2) Listed connections to aluminum or copper busbars not or enclosure is grounded by one of the means specified in less than 6 mm x 50 mm (1/4 in. x 2 in.). Where alu- 250.134. minuet busbars are used, the installation shall comply (4) Grounding Electrode Conductor, Multiple Sepa- with 250.64(A).(3) The exothermic welding process. rately Derived Systems. Where more than one separately derived system is installed, it shall be permissible to con- Tap conductors shall be connected to the common nect a tap from each separately derived system to a com- grounding electrode conductor in such a manner that the mon grounding electrode conductor. Each tap conductor common grounding electrode conductor remains without a shall connect the grounded conductor of the separately de- splice or joint. 2008 Edition NATIONAL ELECTRICAL CODE. 70_101 250.32 ARTICLE 250--GROUNDING AND BONDING (5) Installation.The installation of all grounding electrode (c) Impedance Grounded System. The grounded con- conductors shall comply with 250.64(A), (B), (C), and (E). ductor of an impedance grounded neutral system shall be installed in accordance with 250.36 or 250.186. (6) Bonding. Structural steel and metal piping shall be connected to the grounded conductor of a separately der (B) Ungrounded Systems. The equipment of an un- rived system in accordance with 250.104(D). grounded separately derived system shall be grounded as (7) Grounding Electrode. The grounding electrode shall specified in 250.30(B)(1) and (13)(2). be as near as practicable to and preferably in the same area (1) Grounding Electrode Conductor. A grounding elec- as the grounding electrode conductor connection to the sys- trode conductor, sized in accordance with 250.66 for the tem.The grounding electrode shall be the nearest one of the derived phase conductors, shall be used to connect the following: metal enclosures of the derived system to the grounding (1) Metal water pipe grounding electrode as specified in electrode as specified in 250.30(B)(2). This connection 250.52(A)(1) shall be made at any point on the separately derived system (2) Structural metal grounding electrode as specified in from the source to the first system disconnecting means. 250.52(A)(2) (2) Grounding Electrode. Except as permitted by 250.34 Exception No. 1: Any of the other electrodes identified in for portable and vehicle-mounted generators, the grounding 250.52(A) shall be used where the electrodes specified by electrode shall comply with 250.30(A)(7). 250.30(A)(7) are not available. Exception No. 2 to (1) and(2): Where a separately derived 250.32 Buildings or Structures Supplied by a Feeder(s) system originates in listed equipment suitable for use as or Branch Circuit(s). service equipment, the grounding electrode used for the (A) Grounding Electrode. Building(s) or structure(s) sup- service or feeder equipment shall be permitted as the plied by feeder(s) or branch circuit(s) shall have a ground- grounding electrode for the separately derived system. ing electrode or grounding electrode system installed in FPN: See 250.104(D) for bonding requirements of interior accordance with Part III of Article 250. The grounding metal water piping in the area served by separately derived electrode conductor(s) shall be connected in accordance systems. with 250.32(B) or (C). Where there is no existing ground- ing electrode, the grounding electrode(s) required in 250.50 (8) Grounded Conductor.Where a grounded conductor is shall be installed. installed and the system bonding jumper connection is not located at the source of the separately derived system, Exception: A grounding electrode shall not be required 250.30(A)(8)(a). (A)(8)(b), and (A)(8)(c) shall apply. where only a .single branch circuit, including a multiwire branch, circuit, supplies the building or structure and the (a) Routing and Sizing. This conductor shall be routed branch circuit includes an equipment grounding conductor with the derived phase conductors and shall not be smaller for grounding the normally non—current-carrying metal than the required grounding electrode conductor specified parts of equipment. in Table 250.66 but shall not be required to be larger than the largest ungrounded derived phase conductor. In addi- (B) Grounded Systems. For a grounded system at the tion, for phase conductors larger than 1100 kcmil copper or separate building or structure,an equipment grounding con- 1750 kcmil aluminum, the grounded conductor shall not be ductor as described in 250.118 shall be run with the supply smaller than 121/2 percent of the area of the largest derived conductors and be connected to the building or structure phase conductor. The grounded conductor of a 3-phase, disconnecting means and to the grounding electrode(s).The 3-wire delta system shall have an ampacity not less than equipment grounding conductor shall be used for ground- that of the ungrounded conductors. ing or bonding of equipment, structures, or frames required (b) Parallel Conductors. Where the derived phase to be grounded or bonded. The equipment grounding conductors are installed in parallel, the size of the grounded conductor shall be sized in accordance with 250.122. conductor shall be based on the total circular mil area of the Any installed grounded conductor shall not be connected parallel conductors, as indicated in this section. Where in- to the equipment grounding conductor or to the ground- stalled in two or more raceways, the size of the grounded ing electrode(s). conductor in each raceway shall be based on the size of the Exception: For existing premises wiring systems only, the ungrounded conductors in the raceway but not smaller than grounded conductor run with the supply to the building or 1/0 AWG. ,structure shall be permitted to be connected to the building FPN: See 310.4 for grounded conductors connected in or structure disconnecting means and to the grounding parallel. electrode(s)and shall be used for grounding or bonding of 70-102 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 250--GROUNDING AND BONDING 250.35 equipment, structures, or frames required to be grounded trode(s) shall not be smaller than given in 250.66, based on or bonded where all the requirements of(1), (2), and (3) the largest ungrounded supply conductor. The installation are met: shall comply with Part III of this article. (1) An equipment grounding conductor is not run with t11e supply to the building or structure. 250.34 Portable and Vehicle-Mounted Generators. (2) There are no continuous metallic paths bonded to the (A) Portable Generators.The frame of a portable genera- gmtuiding.tiy tern in each building or structure involved for shall not be required to be connected to a grounding (3) Ground fault protection q/'equipment has not been in- electrode as defined in 250.52 for a system supplied by the stalled on the supply side of the feeder(s), generator under the following conditions: Where the grounded conductor is used for grounding in (l) The generator supplies only equipment mounted on the accordance with the provision of this exception, the size of generator, cord-and-plug-connected equipment through receptacles mounted on the generator, or both, and the grounded conductor shall not be smaller futon lute larger of either of'the following: (2) The normally non-current-carrying metal parts of equip- ment and the equipment grounding conductor terminals of (1) That required hr 220.61 the receptacles are connected to the generator fume. (2) That required h}• 250,IZ2 (B) Vehicle-Mounted Generators.The frame of a vehicle (C) Ungrounded Systems. The grounding electrode(s) shall not be required to be connected to a grounding shall be connected to the building or structure disconnect- electrode as defined in 250.52 for a system supplied by a ing means. generator located on this vehicle under the following conditions: (D) Disconnecting Means Located in Separate Building (1) The frame of the generator is bonded to the vehicle or Structure on the Same Premises. Where one or more frame, and disconnecting means supply one or more additional build- (2) The generator supplies only equipment located on the ings or structures under single management, and where vehicle or cord-and-plug-connected equipment through these disconnecting means are located remote from those receptacles mounted on the vehicle, or both equipment buildings or structures in accordance with the provisions of located on the vehicle and card-and-plug-connected 225.32, Exception No. I and No. 2, 700.12(B)(6), equipment through receptacles mounted on the vehicle 70I,11(B)(5), or 702.11, all of the following conditions or on the generator, and shall be met: (1) The connection of the grounded conductor to the (3) The normally non-current-carrying metal parts of equipment and the equipment grounding conductor ter- grounding electrode, to normally non-current-carrying minals of the receptacles are connected to the generator metal parts of equipment, or to the equipment ground- frame ing conductor at a separate building or structure shall not be made, (C) Grounded Conductor Bonding. A system conductor (2) An equipment grounding conductor for grounding and that is required to be grounded by 250.26 shall be con- bonding any normally non-current-carrying metal parts netted to the generator frame where the generator is a coin- of equipment, interior metal piping systems, and build- ponent of a separately derived system. ing or structural metal frames is run with the circuit FPN: For grounding portable generators supplying fixed conductors to a separate building or structure and Con- wiring systems, see 250.20(D), netted to existing grounding electrode(s) required in 250.35 Permanently Installed Generators. A conductor Part III of this article, or, where there are no existing electrodes, the grounding electrodes} required in Pan that provides an effective ground-fault current path shall be III of this article shall be installed where a separate installed with the supply conductors from a permanently building or structure is supplied by more than one installed generators) to the first disconnecting mean(s) in accordance with (A) or (B). branch circuit. (3) The connection between the equipment grounding con- (A) Separately Derived System. Where the generator is ductor and the grounding electrode at a separate build- installed as a separately derived system,the requirements in ing or structure shall be made in a junction box, panel- 250.30 shall apply. board, or similar enclosure located immediately inside or outside the separate building or structure. (B) Nonseparately Derived System. Where the generator is not installed as a separately derived system, an equip- (E) Grounding Electrode Conductor. The size of the ment bonding jumper shall be installed between the genera- grounding electrode conductor to the grounding elec- for equipment grounding terminal and the equipment 2(N)8 Edition NATIONAL ELECTRICAL CODF 70-103 250.36 ARTICLE 250—GROUNDING AND BONDING grounding terminal or bus of the enclosure of supplied dis- (D) Neutral Point to Grounding Impedance Conductor connecting mean(s) in accordance with (E)(1) or(11)(2). Routing.The conductor connecting the neutral point of the transformer or generator to the grounding impedance shall (I) Supply Side of Generator Overcurrent Device. The be permitted to be installed in a separate raceway from the equipment bonding jumper on the supply side of each gen- ungrounded conductors. It shall not be required to run this erator overcurrent device shall be sized in accordance with conductor with the phase conductors to the first system 250.102(C)based on the size of the conductors supplied by disconnecting means or overcurrent device. the generator. (E) Equipment Bonding Jumper. The equipment bond- (2) Load Side of Generator Overcurrent Device. The ing jumper(the connection between the equipment ground- equipment grounding conductor on the load side of each ing conductors and the grounding impedance) shall be an generator overcurrent device shall be sued in accordance unspliced conductor run from the first system disconnecting with 250.102(D) based on the rating of the overcurrent means or overcurrent device to the grounded side of the device supplied. grounding impedance. 250.36 High-Impedance Grounded Neutral Systems. (F) Grounding Electrode Conductor Location. The High-impedance grounded neutral systems in which a grounding electrode conductor shall be connected at any grounding impedance, usually a resistor, limits the ground- point from the grounded side of the grounding impedance fault current to a low value shall be permitted for 3-phase to the equipment grounding connection at the service ac systems of 480 volts to 1000 volts where all the follow- equipment or first system disconnecting means. ing conditions are met: (G) Equipment Bonding Jumper Size. The equipment (1) The conditions of maintenance and supervision ensure bonding jumper shall be sized in accordance with (1)or(2) that only qualified persons service the installation. as follows: (2) Ground detectors are installed on the system. (1) Where the grounding electrode conductor connection is (3) Line-to-neutral loads are not served. made at the grounding impedance,the equipment bond- High-impedance grounded neutral systems shall com- ing jumper shall be sized in accordance with 250.66, ply with the provisions of 250.36(A) through (G). based on the size of the service entrance conductors for a service or the derived phase conductors for a sepa- (A) Grounding Impedance Location. The grounding im- rately derived system, pedance shall be installed between the grounding electrode (2) Where the grounding electrode conductor is connected conductor and the system neutral point. Where a neutral at the First system disconnecting means or overcurrent point is not available, the grounding impedance shall be device, the equipment bonding jumper shall be sized installed between the grounding electrode conductor and the same as the neutral conductor in 250.36(B). the neutral point derived from a grounding transformer. (B) Grounded System Conductor. The grounded system I1I. Grounding Electrode System and Grounding conductor from the neutral point of the transformer or gen- Electrode Conductor erator to its connection point to the grounding impedance 250.50 Grounding Electrode System.All grounding elec- shall be fully insulated. trodes as described in 250.52(A)(1) through (A)(7) that are The grounded system conductor shall have an ampacity present at each building or structure served shall be bonded of not less than the maximum current rating of the ground- together to form the grounding electrode system. Where ing impedance. In no case shall the grounded system con- none of these grounding electrodes exist, one or more of ductor be smaller than 8 AWG copper or 6 AWG aluminum the grounding electrodes specified in 250.52(A)(4) through or copper-clad aluminum. (A)(8) shall be installed and used. (C) System Grounding Connection.The system shall not Exception: Concrete-encased electrodes of existing buildings be connected to ground except through the grounding or structures shall not be required to be part of the grounding impedance. electrode system where the steel reinforcing bars or rods are not accessible for use without disturbing the concrete. FPN: The impedance is normally selected to limit the ground-fault current to a value slightly greater than or equal to 250.52 Grounding Electrodes. the capacitive charging current of the system. This value of impedance will also limit transient overvoltages to safe values. (A) Electrodes Permitted for Grounding. For guidance, refer to criteria for limiting transient overvolt- ages in ANSMEEE 142-1991, Recommended Practice for (1) Metal Underground Water Pipe. A metal under- Grounding of Industrial and Commetrial Power Svsrems. ground water pipe in direct contact with the earth for 3.0 m 70-104 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 250 GROUNDING AND BONDING 250.53 (10 ft) or more (including any metal well casing bonded to least 6.0 m (20 ft) of bare copper conductor not smaller the pipe) and electrically continuous (or made electrically than 2 AWG. continuous by bonding around insulating joints or insulat- ing pipe) to the points of connection of the grounding elec- {$) Rod and Pipe Electrodes. Rod and pipe electrodes shall not be less than 2.44 m (8 ft) in length and shall trode conductor and the bonding conductors. Interior metal consist of the following materials. water piping located more than 1.52 m(5 ft)from the point of entrance to the building shall not be used as a part of the (a) Grounding electrodes of pipe or conduit shall not grounding electrode system or as a conductor to interconnect he smaller than metric designator 21 (trade size '/a) and, electrodes that are part of the grounding electrode system. where of steel, shall have the outer surface galvanized or otherwise metal-coated for corrosion protection. Exception: fit industrial, commercial, and institutional (b) Grounding electrodes of stainless steel and copper buildings or structures where conditions of maintenance or zinc coated steel shall be at least 15.87 mm (5/s in.) in and .supervision ensure that ont'y qualified persons service diameter, unless listed and not less than 12.70 mm (I/ in.) the installation, interior metal wetter piping located more in diameter. than 1.52 tit (5 ft)ftr>m the point of entrance to the building (6) Other Listed Electrodes. Other listed grounding elec- .shall be permitted cis a part of the grounding electrode trodes shall be permitted. sYste m or as a conductor to interconnect electrodes that are part of the grounding electrode srstenu, provided that the (7) Plate Electrodes. Each plate electrode shall expose not entire length, other than short sections passing perpendicu_ less than 0.186 m` (2 ft`) of surface to exterior soil. Elec- larl},through walls,floors, or ceilings, of the interior metal trodes of iron or steel plates shall be at least 6.4 rum(I/4 in.) water pipe that is being used for the conductor is exposed. in thickness. Electrodes of nonferrous metal shall be at least 1.5 mm (0.06 in.) in thickness. (2) Metal Frame of the Building or Structure.The metal frame of the building or structure that is connected to the (8) Other Local Metal Underground Systems or Struc- earth by any of the following methods: tures. Other local metal underground systems or structures (1) 3.0 m (10 ft) or more of a single structural metal mem- such as piping systems, underground tanks, and under- Der in direct contact with the ground metal well casings that are not bonded to a metal crete that is in direct contact with the earth water pipe. (2) Connecting the structural metal frame to the reinforcing (B) Not Permitted for Use as Grounding Electrodes. bars of a concrete-encased electrode as provided in The following systems and materials shall not be used as 250.52(A)(3) or ground ring as provided in 250.52(A)(4) grounding electrodes: (3) Bonding the structural metal frame to one or more of (1) Metal underground gas piping systems the grounding electrodes as defined in 250.52(A)(5) or (2) Aluminum (A)(7) that comply with 250.56 FPN: See 250.104(B) for bonding requirements of gas (4) Other approved means of establishing a connection to piping. earth (3) Concrete-Encased Electrode. An electrode encased 250.53 Grounding Electrode System Installation. by at least 50 mm (2 in.) of concrete, located horizontally FPN: See 547.9 and 547.10 for special grounding and near the bottom or vertically, and within that portion of a bonding requirements for agricultural buildings. concrete foundation or footing that is in direct contact with (A) Rod, Pipe, and Plate Electrodes. Where practicable, the earth, consisting of at least 6.0 m (20 ft) of one or more rod, pipe, and plate electrodes shall be embedded below bare or zinc galvanized or other electrically conductive permanent moisture level. Rod, pipe, and plate electrodes coated steel reinforcing bars or rods of not less than 13 mm shall be free from nonconductive coatings such as paint or (1/2 in.) in diameter, or consisting of at least 6.0 m (20 ft) of enamel. bare copper conductor not smaller than 4 AWG. Reinforc- ing bars shall be permitted to be bonded together by the (B) Electrode Spacing. Where more than one of the elec- usual steel tie wires or other effective means. Where mul- trodes of the type specified in 250.52(A)(5) or (A)(7) are tiple concrete-encased electrodes are present at a building used, each electrode of one grounding system (including or structure, it shall be permissible to bond only one into that used for air terminals) shall not be less than 1.83 m the grounding electrode system. (6 ft) from any other electrode of another grounding sys- tem. Two or more grounding electrodes that are bonded (4) Ground Ring. A ground ring encircling the building or together shall be considered a single grounding electrode structure, in direct contact with the earth, consisting of at system. 2000 Edition NATIONAL ELECTRICAL COME 70-105 250.54 ARTICLE 250—GROUNDING AND BONDING (C) Bonding Jumper.The bonding jumper(s)used to con- 250.54 Auxiliary Grounding Electrodes. One or more nett the grounding electrodes together to form the ground- grounding electrodes shall be permitted to be connected to ing electrode system shall be installed in accordance with the equipment grounding conductors specified in 250.118 250.64(A), (B), and (E), shall be sized in accordance with and shall not be required to comply with the electrode 250.66, and shall be connected in the manner specified in bonding requirements of 250.50 or 250.53(C) or the resis- 250.70. tance requirements of 250.56, but the earth shall not be used as an effective ground-fault current path as specified (D) Metal Underground Water Pipe. Where used as a in 250.4(A)(5) and 250.4(B)(4). grounding electrode, metal underground water pipe shall meet the requirements of 250.53(D)(1) and (D)(2). 250.56 Resistance of Rod,Pipe, and Plate Electrodes.A (1) Continuity. Continuity of the grounding path or the single electrode consisting of a rod, pipe, or plate that does bonding connection to interior piping shall not rely on wa- not have a resistance to ground of 25 ohms or less shall be ter meters or filtering devices and similar equipment. augmented by one additional electrode of any of the types specified by 250.52(A)(4) through (A)(8). Where multiple (2) Supplemental Electrode Required. A metal under- rod, pipe, or plate electrodes are installed to meet the re- ground water pipe shall be supplemented by an additional quirements of this section, they shall not be less than 1.8 m electrode of a type specified in 250.52(A)(2) through (6 ft) apart. (A)(8). Where the supplemental electrode is a rod, pipe, or FPN: The paralleling efficiency or rods longer than 2.5 m plate type, it shall comply with 250.56. The supplemental (8 ft) is improved by spacing greater than 1.8 m (6 ft). electrode shall be permitted to be bonded to the grounding electrode conductor,the grounded service-entrance conduc- 250.58 Common Grounding Electrode.Where an ac sys- tor, the nonllexible grounded service raceway, or any tem is connected to a grounding electrode in or at a build- grounded service enclosure. ing or structure, the same electrode shall be used to ground Exception: The supplemental electrode shall he permitted conductor enclosures and equipment in or on that building to be banded to the interior metal water piping at any or structure. Where separate services, feeders, or branch convenient point as covered in 250.52(A)(1), Exception. circuits supply a building and are required to be connected to a grounding electrode(s), the same grounding elec- (E) Supplemental Electrode Bonding Connection Size. trode(s) shall be used. Where the supplemental electrode is a rod, pipe, or plate Two or more grounding electrodes that are bonded to- electrode, that portion of the bonding jumper that is the sole gether shall be considered as a single grounding electrode connection to the supplemental grounding electrode shall system in this sense. not be required to be larger than 6 AWG copper wire or 4 AWG aluminum wire. 250.60 Use of Air Terminals.Air terminal conductors and driven pipes, rods, or plate electrodes used for grounding (F) Ground Ring. The ground ring shall be buried at a air terminals shall not be used in lieu of the grounding depth below the earth's surface of not less than 750 mm electrodes required by 250.50 for grounding wiring systems (30 in.). and equipment. This provision shall not prohibit the re- quired bonding together of grounding electrodes of differ- (G) Rod and Pipe Electrodes. The electrode shall be in- ent systems. stalled such that at least 2.44 m(8 ft) of length is in contact with the soil. It shall be driven to a depth of not less than FPN No. 1: See 250.106 for spacing from air terminals. 2.44 m (8 ft) except that, where rock bottom is encoun- See 800.100(D), 810.21(]), and 820.100(D) for bonding of tered, the electrode shall be driven at an oblique angle not electrodes. to exceed 45 degrees from the vertical or, where rock bot- FPN No. 2: Bonding together of all separate grounding tom is encountered at an angle up to 45 degrees, the elec- electrodes will limit potential differences between them and trode shall be permitted to be buried in a trench that is at between their associated wiring systems. least 750 mm (30 in.) deep. The upper end of the electrode shall be flush with or below ground level unless the above- 250.62 Grounding Electrode Conductor Material. The ground end and the grounding electrode conductor attach- grounding electrode conductor shall be of copper, alumi- ment are protected against physical damage as specified in num, or copper-clad aluminum. The material selected shall 250.10. be resistant to any corrosive condition existing at the instal- lation or shall be suitably protected against corrosion, The (H) Plate Electrode. Plate electrodes shall be installed not conductor shall be solid or stranded, insulated, covered, or less than 750 mm (30 in.) below the surface of the earth. bare. 70-106 NATIONAL ELECTRICAL CODE, 2008 Edition ARTICLE 250—GROUNDING AND BONDING 250.64 250.64 Grounding Electrode Conductor Installation. [rode conductor shall be sized in accordance with Table Grounding electrode conductors at the service, at each 250.66, Note 1.A tap conductor shall extend to the inside building or structure where supplied by a feeder(s) or of each service disconnecting means enclosure. The branch circuit(s), or at a separately derived system shall be grounding electrode conductor taps shall be sized in accor- installed as specified in 250.64(A) throubh (F). dance with 250.66 for the Iargest conductor serving the individual enclosure.The tap conductors shall be connected to (A) Aluminum or Copper-Clad Aluminum Conductors, the common grounding electrode conductor by exothermic Bare aluminum or copper-clad aluminum grounding con- welding or with connectors listed as grounding and bonding ductors shall not be used where in direct contact with ma- equipment in such a manner that the Common grounding elec- sonry or the earth or where subject to corrosive conditions, trode conductor remains without a Splice or joint. Where used outside, aluminum or copper-clad aluminum grounding conductors shall not be terminated within (2) Individual Grounding Electrode Conductors. A 450 mm (18 in.) of the earth. grounding electrode conductor shall be connected between the grounded conductor in each service equipment disconnect- (B) Securing and Protection Against Physical Damage. ing means enclosure and the grounding electrode system. Where exposed, a grounding electrode conductor or its en- Each grounding electrode conductor shall be sized in aeeor- closure shall be securely fastened to the surface on which it dance with 250,66 based on the service-entrance conductor(s) is carried.A 4 AWG or larger copper or aluminum ground- supplying the individual service disconnecting means. ing electrode conductor shall be protected where exposed to physical damage.A 6 AWG grounding electrode conductor (3) Common Location. A grounding electrode conductor that is free from exposure to physical damage shall be per- shall be connected to the grounded service conductor(s) in mitted to be run along the surface of the building construe- a wireway or other accessible enclosure on the supply side tion without metal covering or protection where it is se- of the service disconnecting means. The connection shall curely fastened to the construction; otherwise, it shall be in be made with exothermic welding or a connector listed as rigid metal conduit, intermediate metal conduit, rigid non- grounding and bonding equipment. The grounding elec- metallic conduit, electrical metallic tubing, or cable armor. trode conductor shall be sized in accordance with 250.66 Grounding electrode conductors smaller than 6 AWG shall be based on the service-entrance conductor(s) at the common in rigid metal conduit, intermediate metal conduit, rigid non- location where the connection is made. metallic conduit, electrical metallic tubing, or cable armor. (E) Enclosures for Grounding Electrode Conductors. (C) Continuous. Grounding electrode conductor(s) shall Ferrous metal enclosures for grounding electrode conduc- be installed in one continuous length without a splice or tors shall be electrically continuous from the point of at- joint except as permitted in (1) and (2): tachment to cabinets or equipment to the grounding elec- (1) Splicing shall be permitted only by irreversible trode and shall be securely fastened to the ground clamp or compression-type connectors listed as grounding and fitting. Nonferrous metal enclosures shall not be required to bonding equipment or by the exothermic welding pro- be electrically continuous. Ferrous metal enclosures that are cess. not physically continuous from cabinets or equipment to (2) Sections of busbars shall be permitted to be connected the grounding electrode shall be made electrically continu- together to form a grounding electrode conductor. ous by bonding each end of the raceway or enclosure to the • grounding electrode conductor. Bonding shall apply at each (D) Service with Multiple Disconnecting Means Enclo- end and to all intervening ferrous raceways, boxes, and sures. Where a service consists of more than a single en- enclosures between the cabinets or equipment and the closure as permitted in 230.7I(A), grounding electrode grounding electrode. The bonding jumper for a grounding connections shall be made in accordance with (D)(1), electrode conductor raceway or cable armor shall be the (D)(2), or (D)(3). same size as, or larger than, the enclosed grounding elec- trode conductor. Where a raceway is used as protection for a (1) Grounding Electrode Conductor Taps. Where the grounding electrode conductor, the installation shall comply service is installed as permitted by 230.40, Exception No. with the requirements of the appropriate raceway article. 2, a common grounding electrode conductor and grounding electrode conductor taps shall be instalIed,. The common (F) Installation to Electrode(s).Grounding electrode con- grounding electrode conductor shall be sized in accordance ductor(s) and bonding jumpers interconnecting grounding with 250.66, based on the sum of the circular mil area of electrodes shall be installed in accordance with (1), (2), or the largest ungrounded service-entrance conductor(s). (3). The grounding electrode conductor shall be sized for Where the Service-entrance conductors connect directly to a the largest grounding electrode conductor required among service drop or service lateral, the common grounding elec- all the electrodes connected to it. 2008 Edition NATIONAL ELECTRICAL COVE. 70_107 250.66 ARTICLE 250—GROUNDING AND BONDING (1) The grounding electrode conductor shall be permitted Table 250.66 Grounding Electrode Conductor for to be run to any convenient grounding electrode avail- Alternating-Current Systems able in the grounding electrode system where the other electrode(s), if any, are connected by bonding jumpers Size of Largest Ungrounded per 250.53(C). Service-Entrance Conductor or Size of Grounding Equivalent Area for Parallel Electrode Conductor (2) Grounding electrode conductor(s)shall be permitted to be Conductors' (AWG/kcmiq (AWG/I:emil) run to one or more grounding electrode(s) individually. (3) Bonding jualper(s) from grounding electrodes) shall be Aluminum Aluminum or or permitted to be connected to an aluminum or copper bus- Copper-Clad Copper-Clad bat' not less than 6 mm x 50 nun (t!4 in. x 2 in.). The Copper Aluminum Copper Aluminumb busbar shall be securely fastened and shall be installed in an accessible location. Connections shall be made by a 2 or smaller 110 or smaller 8 6 listed connector or by the exothermic welding process. 1 or 1/0 210 or 310 6 4 The grounding electrode conductor shall be permitted to be run to the busbar.Where aluminum busbars are used, 2/0 or 310 410 or 250 4 2 the installation shall comply with 250.64(A). Over 310 Over 250 2 110 250.66 Size of Alternating-Current Grounding Elec- through 350 through 500 trode Conductor.The size of the grounding electrode con- Over 350 Over 500 110 3/0 ductor at the Service, at each building or structure where through 600 through 900 supplied by a feeder(s) or branch circuit(s), or at a sepa- Over 600 Over 900 210 4/0 rately derived system of a grounded or ungrounded ac sys- through 1100 through 1750 tem shall not be less than given in Table 250.66, except as permitted in 250.66(A) through (C). Over 1100 Over 1750 310 250 FAN: See 250.24(C) for size of ac system conductor Notes: brought to service equipment. 1. Where multiple sets of service-entrance conductors are used as permitted in 230.40,Exception No. 2,the equivalent size of the larg- (A) Connections to Rod, Pipe, or Plate Electrodes. est service-entrance conductor shall be determined by the largnt sum of the areas of the corresponding conductors of each set. Where the grounding electrode conductor is connected to 2. Where there are no service-entrance conductors, the grounding rod, pipe, or plate electrodes as permitted in 250.52(A)(5) electrode conductor size shall be determined by the equivalent size of or(A)(7), that portion of the conductor that is the sole connec- the largest service-entrance conductor required for the load to be tion to the grounding electrode shall not be required to be served. larger than 6 AWG copper wire or 4 AWG aluminum wire. 'This table also applies to the derived conductors of separately de- rived ac systems. bSee installation restrictions in 250.64(A). (B) Connections to Concrete-Encased Electrodes. Where the grounding electrode conductor is connected to a concrete-encased electrode as permitted in 250.52(A)(3), that portion of the conductor that is the sole connection to (A) Accessibility. All mechanical elements used to terrni- the grounding electrode shall not be required to be larger note a grounding electrode conductor or bonding jumper to than 4 AWG copper wire. a grounding electrode shall be accessible. (C) Connections to Ground Rings. Where the grounding Exception No. 1: An encased or buried connection to a electrode conductor is connected to a ground ring as permitted concrete-encased, driven, or buried grounding electrode in 250.52(A)(4), that portion of the conductor that is the sole shall not be required to be accessible. connection to the grounding electrode shall not be required to Exception No. 2: Exothermic or irreversible compression be larger than the conductor used for the ground ring. connections used at terminations, together with the me- chanical means used to attach such terminations to fire- 250.68 Grounding Electrode Conductor and Bonding proofed structural metal whether or not the mechanical Jumper Connection to Grounding Electrodes. The con- means is reversible, shall not be required to be accessible. nection of a grounding;electrode conductor at the service,at each building or structure where supplied by a feeder(s) or (g) Effective Grounding Path. The connection of a branch circuit(s), or at a separately derived system and as- grounding electrode conductor or bonding jumper to a sociated bonding jumper(s) shall be trade as specified grounding electrode shall be made in a manner that will 250.68(A) and (B). ensure an effective grounding path, Where necessary to 70-108 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 250—GROUNDING AND BONDING 250.92 ensure the grounding path for a metal piping system used as or structure. The sheath or armor shall be permitted to be a grounding electrode, bonding shall be provided around insulated from the interior metal raceway or piping. insulated joints and around any equipment likely to be dis- connected for repairs or replacement. Bonding jumpers shall (B) Underground Service Raceway Containing Cable. be of sufficient length to permit removal of such equipment An underground metal service raceway that contains a while retaining the integrity of the grounding path, metal-sheathed or armored cable connected to the grounded system conductor shall not be required to be connected to 250.70 Methods of Grounding and Bonding Conductor the grounded system conductor at the building or structure. Connection to Electrodes.The grounding or bonding con- The sheath or armor shall be permitted to be insulated from ductor shall be connected to the grounding electrode by the interior metal raceway or piping, exothermic welding, listed lugs, listed pressure connectors. 250.86 Other Conductor Enclosures and Raceways. Ex- listed clamps, or other listed means. Connections depend- cept as permitted by 250.112(1), metal enclosures and race- ing on solder shall not be used. Ground clamps shall be ways for other than service conductors shall be connected listed for the materials of the grounding electrode and the grounding electrode conductor and, where used on pipe, to the equipment grounding conductor. rod, or other buried electrodes, shall also be listed for direct Exception No. 1: Metal enclosures and rac•esvays for Con- soil burial or concrete encasement. Not more than one con- doctors added to existing installations of open wire, knob- ductor shall be connected to the grounding electrode by a and-tube wiring, and nonmetallic-sheathed cable shall not single clamp or fitting unless the clamp or fitting is listed be required to be connected to the equipment grounding for multiple conductors. One of the following methods conductor where these enclosures or wiring methods cont- shall be used: ply with (1) through (4) as follows: (1) A pipe fitting, pipe plug, or other approved device (1) Do not provide an equipment ground screwed into a pipe or pipe fitting (2) Are in runs of less than 7.5 in (25 ft) (2) A listed bolted clamp of cast bronze or brass, or plain (3) Are free from probable contact with ground, grounded or malleable iron metal, metal lath, or other conductive material (3) For indoor telecommunications purposes only, a listed (4) Are guarded against contact by persons sheet metal strap-type ground clamp having a rigid Exception No. 2: Short sections of metal enclosures or metal base that seats on the electrode and having a raceways used to provide .support or protection of cable strap of such material and dimensions that it is not ctssenthlies from physical damage shall not be required to likely to stretch during or after installation be connected to the equipment grounding conductor. (4) An equally substantial approved means Exception No. 3: A metal elbow shall not be required to be connected to the equipment grounding conductor where it IV. Enclosure, Raceway, and Service Cable is installed in a nonmetallic raceway and is isolated from Connections possible contact by a minimum cover of 450 non (18 in.) to 250.50 Service Raceways and Enclosures. Metal enclo- any part of the elbow or is encased in not less than 50 mm (2 in.) of concrete. sures and raceways for service conductors and equipment shall be connected to the grounded system conductor if the electrical system is grounded or to the grounding electrode V. Bonding conductor for electrical systems that are not grounded. 250.90 General. Bonding shall be provided where neces- Exreption: A metal elbow that is installed in an under- sary to ensure electrical continuity and the capacity to con- ground installation of rigid nonmetallic conduit and is iso- duct safely any fault current likely to be imposed. lated from possible contact by a minimum cover of 450 rnnt (18 in.) to any part of the elbow shall not be required to be 250.92 Services. connected to the grounded system conductor or grounding (A) Bonding of Services. The non—current-carrying metal electrode conductor parts of equipment indicated in 250.92(A)(1) and (A)(2) shall be bonded together. 250.84 Underground Service Cable or Raceway. (1) The service raceways,cable trays,cablebus framework, (A) Underground Service Cable. The sheath or armor of auxiliary gutters, or service cable armor or sheath ex- a continuous underground metal-sheathed or armored ser- cept as permitted in 250.84 vice cable system that is connected to the grounded system (2) All service enclosures containing service conductors, conductor on the supply side shall not be required to be including meter fittings, boxes, or the like, interposed connected to the grounded system conductor at the building in the service raceway or armor 2008 Edition NATIONAL ELECTRICAL CODE 70-109 250.94 ARTICLE 250—GROUNDING AND BONDING • (B) Method of Bonding at the Service. Electrical conti- trode conductors shall he permitted at the service equip- nuity at service equipment, service raceways, and service ment and at the disconnecting means for any additional conductor enclosures shall be ensured by one of the follow- buildings or structures by at least one of the following ing methods: means: (1) Bonding equipment to the grounded service conductor (1) Exposed nonflexible metallic raceways in a manner provided in 250.8 (2) An exposed grounding electrode conductor (2) Connections utilizing threaded couplings or threaded (3) Approved means for the external connection of a cop- bosses on enclosures where made up wrenchtight per or other corrosion-resistant bonding or grounding (3) Threadless couplings and connectors where made up conductor to the grounded raceway or equipment tight for metal raceways and metal-clad cables FPN No. 1: A 6 AWG copper conductor with one end (4) Other listed devices, such as bonding-type locknuts, bonded to the grounded nonliexible metallic raceway or bushings, or bushings with bonding jumpers equipment and with 150 mm (6 in.) or more of the other end made accessible on the outside wall is an example of Bonding jumpers meeting the other requirements of this the approved means covered in 250.94,Exception item(3). article shall be used around concentric or eccentric knock- FPN No.2: See 800.100, 810.21, and 820.100 for bonding outs that are punched or otherwise formed so as to impair and grounding requirements for communications circuits, the electrical connection to ground. Standard locknuts or radio and television equipment, and CATV circuits. bushings shall not be the sole means for the bonding re- quired by this section. 250.96 Bonding Other Enclosures. (A) General. Metal raceways, cable trays, cable armor, 250.94 Bonding for Other Systems. An intersystem cable sheath, enclosures, frames, fittings, and other metal bonding termination for connecting intersystem bonding non–current-carrying parts that are to serve as grounding and grounding conductors required for other systems shall conductors, with or without the use of supplementary be provided external to enclosures at the service equipment equipment grounding conductors, shall be bonded where and at the disconnecting means for any additional buildings necessary to ensure electrical continuity and the capacity to or structures.The intersystem bonding termination shall be conduct safely any fault current likely to be imposed on accessible for connection and inspection. The intersystem them. Any nonconductive paint, enamel, or similar coating bonding termination shall have the capacity for connection shall be removed at threads, contact points, and contact of not less than three intersystem bonding conductors.The surfaces or be connected by means of fittings designed so intersystem bonding termination device shall not interfere as to make such removal unnecessary. with opening a service or metering equipment enclosure. The intersystem bonding termination shall be, one of the (B) Isolated Grounding Circuits. Where installed for the following: reduction of electrical noise (electromagnetic interference) (1) A Set of terminals securely mounted to the meter enclo- on the grounding circuit, an equipment enclosure supplied sure and electrically connected to the meter enclosure. by a branch circuit shall be permitted to be isolated from a The terminals shall be listed as grounding and bonding raceway containing circuits supplying only that equipment equipment. by one or more listed nonmetallic raceway fittings located at the point of attachment of the raceway to the equipment en- (2) Abonding bar near the service equipment enclosure, closure. The metal raceway shall comply with provisions of meter enclosure, or raceway for service Conductors. this article and shall be supplemented by an internal insulated The bonding bar shall be connected with a minimum equipment grounding conductor installed in accordance with 6 AWG copper conductor to an equipment grounding 250.146(D) to ground the equipment enclosure. conductor(s) in the service equipment enclosure,meter enclosure, or exposed non$exible metallic raceway. FPN: Use of an isolated equipment grounding conductor (3) A bonding bar near the grounding electrode conductor. does not relieve the requirement for grounding the raceway The bonding bar shall be connected to the grounding system. electrode conductor with a minimum 6 AWG copper 250.97 Bonding for Over 250 Volts. For circuits of over conductor. 250 volts to ground, the electrical continuity of metal race- Exception: In existing buildings or structures where any of `Mays and cables with metal sheaths that contain any con- the intersystem bonding and grounding conductors required ductor other than service conductors shall be ensured by by 770.93, 800.100($), 810.21(F), 820.100(B), 830.100(B) one or more of the methods specified for services in exist, installation of the intersystem bonding termination is 250.92(B), except for (B)(t), not required. An accessible means external to enclosures Exception: Where oversized, concentric, or eccentric for connecting intersystem bonding and grounding elec- knockouts are not encountered, or where a box or enclosure 70-110 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 250—GROUNDING AND BONDING 250.104 with concentric or eccentric knockouts is listed to provide a or cables, the equipment bonding jumper, where routed reliable bonding connection, the,following methods shall be with the raceways or cables, shall be run in parallel. The permitted: size of the bonding jumper for each raceway or cable shall (1) Threadless Couplings and connectors for cables x•ith be based on the size of the service-entrance conductors in metal sheaths each raceway or cable. (2) Two locknuts, on rigid metal conduit or intermediate (D) Size — Equipment Bonding Jumper on Load Side metal conduit, one inside and one outside of boxes and of Service.The equipment bonding jumper on the load side cabinets of the service overcurrent devices shall be sized, as a mini- (3) Fittings tti•ith shoulders that seat finnI' against the box mum, in accordance with the sizes listed in Table 250.122, or cabinet, such as electrical metallic tubing c•onnec- but shall not be required to be larger than the largest un- tors,flexible metal conduit connectors, and cable con- grounded circuit conductors supplying the equipment and nec•tors, with one locknut on the inside of boxes and shall not be smaller than 14 AWG, cabinets A single common continuous equipment bonding (4) Listed fittings jumper shall be permitted to connect two or more raceways or cables where the bonding jumper is sized in accordance 250.98 Bonding Loosely Jointed Metal Raceways. Ex- with Table 250.122 for the largest overcurrent device sup- pansion fittings and telescoping sections of metal raceways plying circuits therein. shall be made electrically continuous by equipment bond- ing jumpers or other means. (E) Installation. The equipment bonding jumper shall be permitted to be installed inside or outside of a raceway or 250.100 Bonding in Hazardous (Classified) Locations. enclosure. Where installed on the outside, the length of the Regardless of the voltage of the electrical system, the elec- equipment bonding jumper shall not exceed 1.8 m (6 ft) trical continuity of non--current-carrying metal parts of and shall be routed with the raceway or enclosure. Where equipment, raceways, and other enclosures in any hazard- installed inside a raceway, the equipment bonding jumper ous(classified) location as defined in 500.5 shall be ensured shall comply with the requirements of 250.119 and by any of the bonding methods specified in 250.92(0)(2) 250.148. through (13)(4). One or more of these bonding methods Exception: An equipment bonding jumper longer than shall be used whether or not equipment grounding conduc- 1.8 in (6 ft) shall be permitted tit outside pole locations for tors of the wire type: are installed. the purpose of bonding or grounding isolated sections of 250.102 Equipment Bonding Jumpers. metal raceways or elbows installed in exposed risers of metal conduit or other metal raceway. (A) Material.Equipment bonding jumpers shall be of cop- per or other corrosion-resistant material. A bonding jumper 250.104 Bonding of Piping Systems and Exposed Struc- shall be a wire, bus, screw, or similar suitable conductor. tural Steel. (B) Attachment. Equipment bonding jumpers shall be at- (A) Metal Water Piping. The metal water piping system tached in the manner specified by the applicable provisions shall be bonded as required in (A)(]), (A)(2), or (A)(3) of of 250.8 for circuits and equipment and by 250.70 for this section. The bonding jumper(s) shall be installed in grounding electrodes. accordance with 250.64(A), (0), and (E). The points of attachment of the bonding jumper(s) shall be accessible. (C) Size—Equipment Bonding Jumper on Supply Side (l) General. Metal water piping stems} installed in or of Service. The bonding jumper shall not be smaller than p p g 5 y` the sizes shown in Table 250.66 for grounding electrode attached to a building or structure shall be bonded to the service equipment enclosure, the grounded conductor at the conductors. Where the service-entrance phase conductors service, the grounding electrode conductor where of sufi- are larger than 1100 kcmil copper or 1750 kcmil aluminum, cient size, or to the one or more g oundin electrodes used. the bonding jumper shall have an area not less than 121/ The bonding jumper(s) shall be sized in accordance with percent of the area of the largest phase conductor except Table 250.66 except as permitted in 250.104(A)(2) and that, where the phase conductors and the bonding jumper (A)(3). are of different materials (copper or aluminum), the mini- mum size of the bonding jumper shall be based on the (2) Buildings of Multiple Occupancy. In buildings of assumed use of phase conductors of the same material as multiple occupancy where the metal water piping system(s) the bonding jumper and with an ampacity equivalent to that installed in or attached to a building or structure for the of the installed phase conductors. Where the service- individual occupancies is metallically isolated from all entrance conductors are paralleled in two or more raceways other occupancies by use of nonmetallic water piping, the 2008 Edition NATIONAL ELECTRICAL CODE 70-111 250.104 ARTICLE 250—GROUNDING AND BONDING metal water piping system{s} for each occupancy shall be nearest available point of the metal water piping system(s) permitted to be bonded to the equipment grounding termi- in the area served by each separately derived system. This nal of the panelboard or switchboard enclosure (other than connection shall be made at the same point on the sepa- service equipment) supplying that occupancy. The bonding rately derived system where the grounding electrode con- jumper shall be sized in accordance with Table 250.122, ductor is connected. Each bonding jumper shall be sized in based on the rating of the overeurreat protective device for accordance with Table 250.66 based on the largest un- the circuit Supplying the occupancy. grounded conductor of the separately derived system. (3) Multiple Buildings or Structures Supplied by a Exception No. 1: A separate bonding juniper to the metal Feeder(s) or Branch Circuit(s). The metal water piping water piping system shall not be required where the metal system(s) installed in or attached to a building or structure water piping system is used as the grounding electrode for shall be bonded to the building or structure disconnecting the separately derived system and the water piping system means enclosure where located at the building or structure, is in the area served. to the equipment grounding conductor run with the supply Exception No. 2: A separate water piping bonding jumper conductors, or to the one or more grounding electrodes shall not be required where the metal frame of a building or used. The bonding jumper(s) shall be sized in accordance structure is used as the grounding electrode for a sepa- with 250.66, based on the size of the feeder or branch rately derived system and is bonded to the metal water circuit conductors that supply the building. The bonding piping in the area served by the separately derived system. jumper shall not be required to be larger than the largest ungrounded feeder or branch circuit conductor supplying (2) Structural Metal. Where exposed structural metal that the building. is interconnected to form the building frame exists in the area served by the separately derived system, it shall be (B) Other Metal Piping. Where installed in or attached to bonded to the grounded conductor of each separately de- a building or structure, a metal piping system(s), including rived system. This connection shall be made at the same gas piping, that is likely to become energized shall be point on the separately derived system where the grounding bonded to the service equipment enclosure, the grounded electrode conductor is connected. Each bonding jumper conductor at the service, the grounding electrode conductor shalt be sized in accordance with Table 250.66 based on where of sufficient size, or the one or more grounding elec- the largest ungrounded conductor of the separately de- trodes used. The bonding jumper(s) shall be sized in actor- rived system. dance with 250.122, using the rating of the circuit that is likely to energize the piping system(s). The equipment Exception No. 1: A separate banding jumper to the build- grounding conductor for the circuit that is likely to energize ing structural metal shall not be required where the metal the piping shall be permitted to serve as the bonding means. frame of a building or structure is used as the grounding The points of attachment of the bonding jumper(s) shall be electrode for the separately derived system. accessible. Exception No. 2: A separate bonding jumper to the build- FPN: Bonding all piping and metal air ducts within the ing structural metal shall not be required where the water premises will provide additional safety. piping of a building or structure is used as the grounding electrode for a separately derived system and is bonded to (C) Structural Metal. Exposed structural metal that is in- the building structural metal in the area served by the sepa- terconnected to form a metal building frame and is not rately derived system. intentionally grounded and is likely to become energized shall be bonded to the service equipment enclosure, the (3) Common Grounding Electrode Conductor. Where a grounded conductor at the service, the grounding electrode common grounding electrode conductor is installed for conductor where of sufficient size, or the one or more multiple separately derived systems as permitted by grounding electrodes used. The bonding jumper(s) shall be 250.30(A)(4), and exposed structural metal that is intercon- sized in accordance with Table 250.66 and installed in ac- netted to form the building frame or interior metal piping cordance with 250.64(A), (B), and (E). The points of at- exists in the area served by the separately derived system, tachment of the bonding jumper(s) shall be accessible. the metal piping and the structural metal member shall be bonded to the common grounding electrode conductor. (D) Separately Derived Systems. Metal water piping sys- tems and structural metal that is interconnected to forma Exception: A separate banding jumper from each derived building frame shall be bonded to separately derived sys_ system to metal water piping and to structural metal mem- tems in accordance with (D}{1) through (D)(3}. bets shall not be required where the metal water piping crud the structural metal members in the area served by the (1) Metal Water Piping System(s).The grounded conduc- separately derived system are bonded to the common for of each separately derived system shall be bonded to the grounding electrode conductor. 70-112 NATIONAL ELECTRICAL CODE 2009 Edition ARTICLE 250—GROUNDING AND BONDING 250.112 250.106 Lightning Protection Systems. The lightning the kinds of equipment described in 250.112(A) through protection system ground terminals shall be bonded to the (K),and non--current-carrying metal parts of equipment and building or structure grounding electrode system. enclosures described in 250.112(L) and (M), shall be eon- nected to the equipment grounding conductor regardless of FPN No. 1: See..50.60 for use of air terminals. For further voltage. information, see NFPA 750-2008, Standard for the Instal- lation of Lightning Protection Systems, which contains de- tailed information on grounding, bonding, and sideflash (A) Switchboard Frames and Structures. Switchboard distance From lightning protection systems. frames and structures supporting switching equipment, ex- FPN No. 2: Metal raceways, enclosures, frames, and other cept frames of 2-wire do switchboards where effectively non-current-carrying metal parts of electrical equipment in- insulated from ground. stalled on a building equipped with a lightning protection sys- tem may require bonding or spacing From the lightning pro- (B) Pipe Organs. Generator and motor frames in an elec- tection conductors in accordance with NFPA 780-2008, trically operated pipe organ, unless effectively insulated Standard for the Installation of Lightning Ptnrtection S.Ysterns• from ground and the motor driving it. VI. Equipment Grounding and Equipment Grounding (C) Motor Frames. Motor frames, as provided by Conductors 430.242. 250.110 Equipment Fastened in Place or Connected by (D) Enclosures for Motor Controllers. Enclosures for Permanent Wiring Methods (Fixed). Exposed non– motor controllers unless attached to ungrounded portable current-carrying metal parts of fixed equipment likely to equipment. become energized shall be connected to the equipment (E) Elevators and Cranes.Electrical equipment for eleva- grounding conductor under any of the following conditions: tors and cranes. (1) Where within 2.5 m (8 ft) vertically or 1.5 m (5 ft) horizontally of ground or grounded metal objects and (F) Garages, Theaters, and Motion Picture Studios. subject to contact by persons Electrical equipment in commercial garages, theaters, and (2) Where located in a wet or damp location and not motion picture studios, except pendant lampholders sup- isolated plied by circuits not over 150 volts to ground. (3) Where in electrical contact with metal (G) Electric Signs. Electric signs, outline lighting, and as- (4) Where in a hazardous (classified) location as covered sociated equipment as provided in 600.7. by Articles 500 through 517 (5) Where supplied by a metal-clad, metal-sheathed, metal- (H) Motion Picture Projection Equipment. Motion pic- raceway, or other wiring method that provides an ture projection equipment. equipment ground, except as permitted by 250.86, Ex- (1) Remote-Control,Signaling,and Fire Alarm Circuits. ception No. 2, for short sections of metal enclosures Equipment supplied by Class 1 circuits shall be grounded (6) Where equipment operates with any terminal at over unless operating at less than 50 volts. Equipment supplied 150 volts to ground by Class 1 power-limited circuits, by Class 2 and Class 3 Exception No. 1: Metal frames of electrically heated appli- remote-control and signaling circuits, and by fire alarm cir- ances, exempted by special permission, in which case the cuits shall be grounded where system grounding is required frames shall he pennanentl}• and effectively insulated from by Part I1 or Part VIII of this article. ground. (T) Luminaires. Luminaires as provided in Part V of Ar- Exc•eption No. 2: Distribution apparatus, such as trans- ticle 410. former and capacitor rases, mounted on wooden poles, tit a height exceeding 2.5 m (8 ft) above ground or grade level. (K) Skid-Mounted Equipment. Permanently mounted electrical equipment and skids shall be connected to the Exception No. 3: Listed equipment protected by a system of equipment grounding conductor sized as required by double insulation, or its equivalent, shall not be required to 250.122. be connected to the equipment grounding conductor. Where such a system is empinved, the equipment shall be distinc- (L) Motor-Operated Water Pumps. Motor-operated wa- tively marked. ter pumps, including the submersible type. 250.1I2 Fastened in Place or Connected by Permanent (M) Metal Well Casings. Where a submersible pump is Wiring Methods (Fixed) —Specific. Except as permitted used in a metal well casing, the well casing shall be con- in 250.112(I), exposed, non–current-carry ing metal parts of neeted to the pump circuit equipment grounding conductor, 2008 Edition NATIONAL ELECTRICAL CODE 70-,113 250.114 ARTICLE 250—GROUNDING AND BONDING 250.114 Equipment Connected by Cord and Plug. Un- Exception: Tools and portable handlamps likely to be used der any of the conditions described in 250.114(1) through in wet or conductive locations shall not be required to be (4), exposed non-current-carrying metal parts of cord-and- connected to an equipment grounding conductor where plug-connected equipment likely to become energized shall supplied through an isolating transformer with an un- be connected to the equipment grounding conductor. grounded secondary of not over 50 volts. Exception: Listed tools, listed appliances, and listed equip- 250.116 Nonelectrical Equipment. The metal parts of the meat covered in 250.114(2) through (4) shall not be re- following nonelectrical equipment described in this section quired to be connected to an equipment grounding conduc- shall be connected to the equipment grounding conductor: for where protected by a system of double insulation or its (1) Frames and tracks of electrically operated cranes and equivalent. Double insulated equipment shall be distinc- hoists tively marked. (2) Frames of nonelectrically driven elevator cars to which (1) In hazardous (classified) locations (see Articles 500 electrical conductors are attached through 517) (2) Where operated at over 150 volts to ground (3) Hand-operated metal shifting ropes or cables of electric elevators Exception No. 1: Motors, where guarded, shall not be re- FPN: Where extensive metal in or on buildings may be- quired to be connected to an equipment grounding conductor. come energized and is subject to personal contact,adequate Exception No. 2: Metal frames of electrically heated appli- bonding and grounding will provide additional safety, ances, exempted by special permission, shall not be re- 250.118 Types of Equipment Grounding Conductors. quired to be connected to an equipment grounding conduc- tor, in which case the frames shall be permanently and The equipment grounding conductor run with or enclosing e�'ectively insulated from ground. the circuit conductors shall be one or more or a combina- tion of the following: (3) In residential occupancies: a. Refrigerators, freezers, and air conditioners FPN: For effective ground-fault current path, see 250.2 Definition. b. Clothes-washing, clothes-drying, dish-washing ma- chines; kitchen waste disposers; information tech- (1) A copper, aluminum, or copper-clad aluminum con- nology equipment; sump pumps and electrical ductor. This conductor shall be solid or stranded; in- aquarium equipment sulated, covered, or bare; and in the form of a wire or c. Hand-held motor-operated tools, stationary and a busbar of any shape. fixed motor-operated tools, and light industrial (2) Rigid metal conduit. motor-operated tools (3) Intermediate metal conduit. d. Motor-operated appliances of the following types: hedge clippers, lawn mowers, snow blowers, and (4) Electrical metallic tubing. wet scrubbers (5) Listed flexible metal conduit meeting all the following e. Portable handlamps conditions: (4) In other than residential occupancies: a. The conduit is terminated in listed fittings. a. Refrigerators, freezers, and air conditioners b. The circuit conductors contained in the conduit are b. Clothes-washing, clothes-drying, dish-washing ma- protected by overcurrent devices rated at 20 am- chines; information technology equipment; sump peres or less. pumps and electrical aquarium equipment c. The combined length of flexible metal conduit and c. Hand-held motor-operated tools, stationary and flexible metallic tubing and liquidtight flexible fixed motor-operated tools, and light industrial metal conduit in the same ground return path does motor-operated tools not exceed 1.8 m (6 ft). d. Motor-operated appliances of the following types: d. Where used to connect equipment where flexibility hedge clippers, lawn mowers, snow blowers, and is necessary after installation, an equipment wet scrubbers grounding conductor shall be installed. e. Portable handlamps (6) Listed liquidtight flexible metal conduit meeting all f. Cord-and-plug-connected appliances used in damp the following conditions: or wet locations or by persons standing on the a. The conduit is terminated in listed fittings. ground or on metal floors or working inside of metal b. For metric designators 12 through 16 (trade sizes tanks or boilers "la through th), the circuit conductors contained in g. Tools likely to be used in wet or conductive lo- the conduit are protected by overcurrent devices cations rated at 20 amperes or less. 70-.114 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE,250 GROUNDING AND BONDING 250.120 c. For metric designators 21 through 35 (trade sizes Exception: Power-limited, Class 2 or Class 3 circuit cables ;/a through 1 /a),the circuit conductors contained in containing only circuits operating at less than 50 volts shall the conduit are protected by overcurrent devices he permitted to use a conductor with green insulation for rated not more than 60 amperes and there is no other than equipment grounding purposes, flexible metal conduit, flexible metallic tubing, or liquidtight flexible metal conduit in trade sizes (A) Conductors Larger Than 6 AWG. Equipment metric designators 12 through 16 (trade sizes ;/H grounding conductors larger than 6 AWG shall comply with through I 12) in the grounding path. 250.119(A)(1) and (A)(2), d. The combined length of flexible metal conduit and (1) An insulated or covered conductor larger than 6 AWG flexible metallic tubing and liquidtight flexible shall be permitted, at the time of installation, to be metal conduit in the same ground return path does not exceed 1.8 m (6 ft). permanently identified as an equipment grounding con- e. Where used to connect equipment where flexibility ductor at each end and at every point where the con- is necessary after installation, an equipment ductor is accessible. grounding conductor shall be installed. Exception: Conductors larger than 6 AWG .shall not be (7) Flexible metallic tubing where the tubing is termi_ required to be marked in conduit bodies that contain no nated in fisted fittings and meeting the following con- splices or unused hubs. ditions: (2) Identification shall encircle the conductor and shall be a. The circuit conductors contained in the tubing are accomplished by one of the following: protected by overcurrent devices rated at 20 am- a. Stripping the insulation or covering from the entire peres or less. exposed length b. The combined length of flexible metal conduit and b. Coloring the insulation or covering green at the ter- flexible metallic tubing and liquidtight flexible ruination metal conduit in the same ground return path does c. Marking the insulation or covering with green tape not exceed 1.8 m (6 ft). or green adhesive labels at the termination (8) Armor of Type AC cable as provided in 320.108. {9} The capper sheath of mineral-insulated, metal- (�) Multiconductor Cable. Where the conditions of sheathed cable. maintenance and supervision ensure that only qualified per- sons service the installation, one or more insulated conduc- ing Type MC cable where listed and identified far ground- tors in a multiconductor cable, at the time of installation, ing in accordance with the following: shall be permitted to be permanently identified as equipment a. The combined metallic sheath and grounding con- grounding conductors at each end and at every point where the ductor of interlocked metal tape--type MC cable conductors are accessible by one of the following means: b. The metallic sheath or the combined metallic sheath and grounding conductors of the smooth or (1) Stripping the insulation from the entire exposed length corrugated tube-type MC cable (2) Coloring the exposed insulation green (11) Cable trays as permitted in 392.3 and 392.7. (3) Marking the exposed insulation with green tape or (12) Cablebus framework as permitted in 370.3. green adhesive labels (13) Other listed electrically continuous metal raceways (C) Flexible Cord. An uninsulated equipment grounding and listed auxiliary gutters. conductor shall be permitted, but, if individually covered, (14) Surface metal raceways listed for grounding. the covering shall have a continuous outer finish that is 250.119 Identification of Equipment Grounding Con- either green or green with one or more yellow stripes. ductors. Unless required elsewhere in this Code, equip- 250.120 Equipment Grounding Conductor Installation. ment grounding conductors shall be permitted to be bare, An equipment grounding conductor shall be installed in covered, or insulated. Individually covered or insulated accordance with 250.120(A), (13), and (C), equipment grounding conductors shall have a continuous outer finish that is either green or green with one or more (A) Raceway, Cable Trays, Cable Armor, Cablebus, or yellow stripes except as permitted in this section. Conduc- Cable Sheaths. Where it consists of a raceway, cable tray, tors with insulation or individual covering that is green, cable armor, cablebus framework, or cable sheath or where green with one or more yellow stripes, or otherwise identi- it is a wire within a raceway or cable, it shall be installed in fied as permitted by this section shall not be used for un- accordance with the applicable provisions in this Code us- grounded or grounded circuit conductors. ing fittings for joints and terminations approved for use 2008 F.ditit)n NATIONAL ELECTRICAL CODE 70-11.5 250.122 ARTICLE 250—GROUNDING AND BONDING with the type raceway or cable used. All connections, an instantaneous-trip circuit breaker or a motor short-circuit joints, and fittings shall be made tight using suitable tools. protector, the equipment grounding conductor shall be FPN: See the UL guide information on FfU. systems for sized not smaller than that given by 250.122(A) using the equipment grounding conductors installed in a raceway that maximum permitted rating of a dual element time-delay fuse are part of an electrical circuit protective system or a fire- selected for branch-circuit short-circuit and ground-fault pro- rated cable listed to maintain circuit integrity. tection in accordance with 430.52(0)(1),Exception No. 1. (B) Aluminum and Copper-Clad Aluminum Conduc- (E) Flexible Cord and Fixture Wire. The equipment tors. Equipment grounding conductors of bare or insulated grounding conductor in a flexible cord with the largest cir- aluminum or copper-clad aluminum shall be permitted. cuit conductor 10 AWG or smaller, and the equipment Bare conductors shall not come in direct contact with ma- grounding conductor used with fixture wires of any size in sonry or the earth or where subject to corrosive conditions. accordance with 240.5, shall not be smaller than 18 AWG Aluminum or copper-clad aluminum conductors shall not copper and shall not be smaller than the circuit conductors. be terminated within 450 mm (18 in.) of the earth. The equipment grounding conductor in a flexible cord with a circuit conductor larger than 10 AWG shall be sized in (C) Equipment Grounding Conductors Smaller Than accordance with Table 250.122. 6 AWG. Equipment grounding conductors smaller than 6 AWG shall be protected from physical damage by a race- (F) Conductors in Parallel. Where conductors are run in way or cable armor except where run in hollow spaces of parallel in multiple raceways or cables as permitted in walls or partitions, where not subject to physical damage, 310.4, the equipment grounding conductors, where used, or where protected from physical damage. shall be run in parallel in each raceway or cable. Each parallel equipment grounding conductor shall be 250.122 Size of Equipment Grounding Conductors. sized on the basis of the ampere rating of the overcurrent (A) General. Copper, aluminum, or copper-clad aluminum device protecting the circuit conductors in the raceway or equipment grounding conductors of the wire type shall not cable in accordance with Table 250.122. be smaller than shown in Table 250.122, but in no case (G) Feeder Taps. Equipment grounding conductors run shall they be required to be larger than the circuit conduc- with feeder taps shall not be smaller than shown in Table tors supplying the equipment. Where a cable tray, a race- 250.122 based on the rating of the overcurrent device ahead way, or a cable armor or sheath is used as the equipment of the feeder but shall not be required to be larger than the grounding conductor, as provided in 250.11$ and tap conductors. 250.134(A), it shall comply with 250.4(A)(5) or (13)(4). (B) Increased in Size. Where ungrounded conductors are 250.124 Equipment Grounding Conductor Continuity. increased in size, equipment grounding conductors, where installed, shall be increased in size proportionately accord- (A) Separable Connections. Separable connections such ing to the circular mil area of the ungrounded conductors, as those provided in drawouk equipment or attachment plugs and mating connectors and receptacles shall provide (C) Multiple Circuits. Where a single equipment ground- for first-make, last-break of the equipment grounding con- ing conductor is run with multiple circuits in the same ductor. First-make, last-break shall not be required where raceway,cable, or cable tray, it shall be sized for the largest interlocked equipment, plugs, receptacles, and connectors overcurrent device protecting conductors in the raceway, preclude energization without grounding continuity. cable, or cable tray. Equipment grounding conductors in- stalled in cable trays shall meet the minimum:requirements (B) Switches. No automatic cutout or switch shall be of 392.3(B}(l)(c}. placed in the equipment grounding conductor of a premises wiring system unless the opening of the cutout or switch (D) Motor Circuits. Equipment grounding conductors for disconnects all sources of energy. motor circuits shall be sized in accordance with (D)(1) or (13)(2). 250.126 Identification of Wiring Device Terminals. The terminal for the connection of the equipment grounding (l.) General. The equipment grounding conductor size conductor shall be identified by one of the following: shall not be smaller than determined by 250.122(A) based (1) A green, not readily removable terminal screw with a on the rating of the branch-circuit short-circuit and ground- hexagonal head. fault protective device. (2) green, hexagonal, not readily removable terminal nut. (2) Instantaneous-Trip Circuit Breaker and Motor (3) A green pressure wire connector. if the terminal for Short-Circuit Protector. Where the overcurrent device is the grounding conductor is not visible, the conductor 70-116 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 250—GROUNDING AND BONDING 250.134 Table 250.122 Minimum Size Equipment Grounding source of separately derived systems shall be made in ac- Conductors ror Grounding Raceway and Equipment cordance with 250.30(A)(1), Equipment grounding conduc- tor connections at service equipment shall be made as in- Rating or Setting of dicated in 250.130(A) or (B). For replacement of non-- Automatic Circuit rrent Size (AWG or kcmiU �>roundin t e receptacles with grounding-type rece tacles Device in Circuit Ahead o g-YP P ' ' p or Equipment, Conduit, Aluminum or and for branch-circuit extensions only in existing installa- etc., Not Exceeding Copper-Clad tions that do not have an equipment grounding conductor in (Amperes) Copper Aluminum* the branch circuit, connections shall be permitted as indi- 15 14 12 cated in 250.130(C). 20 12 10 (A) For Grounded Systems. The connection shall be 30 10 8 made by bonding the equipment grounding conductor to the 40 10 8 grounded service conductor and the grounding electrode 60 10 8 conductor. 100 8 6 200 6 4 (B) For Ungrounded Systems. The connection shall be 300 4 2 made by bonding the equipment grounding conductor to the 400 ; I grounding electrode conductor. 500 2 110 (C) Nongrounding Receptacle Replacement or Branch 6(x) I 210 Circuit Extensions. The equipment grounding conductor 800 110 310 of a grounding-type receptacle or a branch-circuit extension 1000 210 410 shall be permitted to be connected to any of the following: 1200 310 250 (1) Any accessible point on the grounding electrode sys- 16(x) 410 350 tem as described in 250.50 2000 250 400 (2) Any accessible point on the grounding electrode con- 2500 350 600 ductor 3(x)0 400 600 (3) The equipment grounding terminal bar within the en- 4000 Sq0 800 closure where the branch circuit for the receptacle or 5000 700 12(x) branch circuit originates 6000 800 1200 (4) For grounded systems, the grounded service conductor Note: Where necessary to comply with 250.4(A)(5)250.4(A)(5) or (B)(4), the within the service equipment enclosure equipment grounding conductor shall be sized larger than given in this (5) For ungrounded systems, the grounding terminal bar table, within the service equipment enclosure `See installation restrictions in 250.120. FPN: See 406.3(D) for the use of a ground-fault circuit- entrance hole shall be marked with the word green or interrupting type of receptacle. ground, the letters G or GR, a grounding symbol, or otherwise identified by a distinctive green color. If 250.132 Short Sections of Raceway. Isolated sections of the terminal for the equipment grounding conductor metal raceway or cable armor, where required to be is readily removable, the area adjacent to the termi- grounded, shall be connected to an equipment grounding nal shall he similarly marked, conductor in accordance with 250.134. FPN: See FPN Figure 250.126. 250.134 Equipment Fastened in Place or Connected by Permanent Wiring Methods (Fixed) —Grounding. Un- less grounded by connection to the grounded circuit con- FPN Figure 250.126 One Example of a Symbol Used to Iden- ductor as permitted by 250.32, 250.140, and 250.142, non- tify the Grounding Termination Point for an Equipment current-carrying meta] parts of equipment, raceways, and Grounding Conductor. other enclosures, if grounded, shall be connected to an equipment grounding conductor by one of the methods specified in 250.134(A) or (B). VII. Methods of Equipment Grounding (A) Equipment Grounding Conductor Types. By con- 250.130 Equipment Grounding Conductor Connec- necting to any of the equipment grounding conductors per- tions. Equipment grounding conductor connections at the mitted by 250.118. 2008 Edition NATIONAL ELECTRICAL.CODE 70-117 250.136 ARTICLE 250—GROUNDING AND BONDING (B) With Circuit Conductors.By connecting to an equip- 250.140 Frames of Ranges and Clothes Dryers. Frames ment grounding conductor contained within the same race- of electric ranges, wall-mounted ovens, counter-mounted way, cable, or otherwise run with the circuit conductors. cooking units, clothes dryers, and outlet or junction boxes Exception No. 1: As provided in 250.130(C), the equip- that are part of the circuit for these appliances shall be connected to the equipment grounding conductor in the meat grounding conductor shall be penmitted to be run manner specified by 250.134 or 250.13$. separately from the circuit conductors. Exception No. 2: For do circuits, the equipment grounding Exception: For existing branch-circuit installations only conductor shall be permitted to be run separately from the where an equipment grounding conductor is not present in circuit conductors. the outlet or junction box, the frames of electric ranges, wall-mounted ovens, counter-mounted cooking units, FPN No. 1: See 250.102 and 250.168 for equipment bond- clothes dryers, and outlet or junction boxes that are part of ing jumper requirements. the circuit for these appliances shall be permitted to be FPN No. 2: See 400.7 for use accords for fixed equipment. connected to the grounded circuit conductor if all the fol- lowing conditions are nnet. 250.136 Equipment Considered Grounded. Under the conditions specified in 250.136(A) and (B), the normally (I) The supply circuit is 120!140-volt, single-phase, noncurrent-carrying metal pans of the equipment shall be 3-wire; or 20SY/I20-volt derived from a 3-phase, considered grounded. 4-wire, wye-connected system. (2) The grounded conductor is not smaller than 10 AWG (A) Equipment Secured to Grounded Metal Supports. copper or 8 AWG aluminum. Electrical equipment secured to and in electrical contact (3) The grounded conductor is insulated, or the grounded with a metal rack or structure provided for its support and conductor is uninsulated and part of a Type SE service- connected to an equipment grounding conductor by one of entrance cable and the branch circuit originates at the the means indicated in 250.134. The structural metal frame service equipment, of a building shall not be used as the required equipment (4) Grounding contacts of receptacles furnished as part of grounding conductor for ac equipment. the equipment are bonded to the equipment. (B) Metal Car Frames. Metal car frames supported by 250.142 Use of Grounded Circuit Conductor for metal hoisting cables attached to or running over metal sheaves or drums of elevator machines that are connected Grounding Equipment. to an equipment grounding conductor by one of the meth- (A) Supply-Side Equipment. A grounded circuit conduc- ods indicated in 250.134. for shall be permitted to ground non-current-carrying metal parts of equipment, raceways, and other enclosures at any 250.138 Cord-and-Plug-Connected Equipment. Non- of the following locations: current-carrying metal parts of cord-and-plug-connected (1) On the supply side or within the enclosure of the ac equipment,if grounded,shall be connected to an equipment service-disconnecting means grounding conductor by one of the methods in 250.138(A) or (B) (2) On the supply side or within the enclosure of the main disconnecting means for separate buildings as provided (A) By Means of an Equipment Grounding Conductor. in 250.32(B) By means of an equipment grounding conductor run with (3) On the supply Side or within the enclosure of the main the power supply conductors in a cable assembly or flexible disconnecting means or overcurrent devices of a sepa- cord properly terminated in a grounding-type attachment rately derived system where permitted by 250.30(A)(1) plug with one fixed grounding contact. {B} Load-Side Equipment. Except as permitted in Exception: The grounding contacting pole of grounding- 250.30(A)(1) and 250.32(B), a grounded circuit conductor type plug-in ground fault circuit interrupters shall be per- shall not be used for grounding non-current-carrying metal mitted to be of the movable, self-restoring type on circuits parts of equipment on the load side of the service discon- operating at not over 150 volts between any two conductors necting means or on the load side of a separately derived or over 150 volts between any conductor and ground system disconnecting means or the overcurrent devices for (B) By Means of a Separate Flexible Wire or Strap. By a separately derived system not having a main disconnect- means of a separate flexible wire or strap, insulated or bare, ing means. connected to an equipment grounding conductor, and pro- Exception No. 1: The frames of ranges, wall-mounted ov- tected as well as practicable against physical damage, ens, counter-mounted cooking units, and clothes dryers un- where part of equipment. der the conditions permitted for existing installations by 70-119 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 250—GROUNDING AND BONDING 250.148 250.140 shall be Permitted to be connected to the grounded in conjunction with the supporting screws to establish circuit conductor. the grounding circuit between the device yoke and Hush- Exception No. 2: It shall be permissible to ground meter type boxes. enclosures by connection to the grounded circuit conductor on the load side of the service disconnect where all of the (C) Floor Boxes. Floor boxes designed far and listed as providing satisfactory ground continuity between the box following conditions apply: and the device shall be permitted. (1) No sen,ic•e ground fault protection is installed. (2) All meter enclosures are located immediatel. adjacent (D) Isolated Receptacles. Where installed for the reduc- to the service disconnecting means. tion of electrical noise (electromagnetic interference)on the (3) The size of the grounded circuit conductor is not grounding circuit, a receptacle in which the grounding ter- smaller than the size specified in Table 250.122 for minal is purposely insulated from the receptacle mounting equipment a groundin � means shall be permitted. The receptacle grounding termi- nal shall be connected to an insulated equipment grounding Exception No, 3: Direct-current systems shall be permitted conductor run with the circuit conductors. This equipment to be grounded on the laud.side of the disconnecting means grounding conductor shall be permitted to pass through one or overcurrent device in accordance with 250364. or more panelboards without a connection to the panel- Exception No. 4: Electrode-ripe boilers operating at over board grounding terminal bar as permitted in 408.40, Ex- 600 volts shall be grounded as required in 490.72(E)(1) ception, so as to terminate within the same building or and 490,74, structure directly at an equipment grounding conductor ter- minal of the applicable derived system or service. Where 250.144 Multiple Circuit Connections. Where equipment installed in accordance with the provisions of this section, is grounded and is supplied by separate connection to more this equipment grounding conductor shall also be permitted than one circuit or grounded premises wiring system, an to pass througb boxes, wireways, or other enclosures with- equipment grounding conductor termination shall be pro- out being connected to such enclosures. vided for each such connection as specified in 250.134 and 250.138. FPN: Use of an isolated equipment grounding conductor does not relieve the requirement for grounding the raceway 250.146 Connecting Receptacle Grounding Terminal to system and outlet box. Box. An equipment bonding jumper shall be used to con- 250.148 Continuity and Attachment of Equipment nett the grounding terminal of a grounding-type receptacle Grounding Conductors to Boxes. Where circuit conduc- to a grounded box unless grounded as in 250.146(A) tors are spliced within a box, or terminated on equipment through (D). The equipment bonding jumper shall be sized within or supported by a box, any equipment grounding con- in accordance with Table 250.122 based on the rating of the ductor(s)associated with those circuit conductors shall be con- overcurrent device protecting the circuit conductors. netted within the box or to the box with devices suitable for (A) Surface-Mounted Box. Where the box is mounted on the use in accordance with 250.148(A) through (E). the surface, direct metal-to-metal contact between the de- Exception: The equipment grounding conductor permitted vice yoke and the box or a contact yoke or device that in 250.146(D) shall not he required to he connected to the complies with 250.146(B) shall be permitted to ground the other equipment grounding conductors or to the box. receptacle to the box.At least one of the insulating washers shall be removed from receptacles that do not have a con- (A) Connections. Connections and splices shall be made tact yoke or device that complies with 250.146(8) to ensure in accordance with 110.14(B) except that insulation shall direct metal-to-metal contact.This provision shall not apply not be required. to cover-mounted receptacles unless the box and cover combination are listed as providing satisfactory ground (B) Grounding Continuity. The arrangement of ground- continuity between the box and the receptacle. A listed ing connections shall be such that the disconnection or the exposed work cover shall be permitted to be the grounding removal of a receptacle, luminaire,or other device fed from and bonding means when (1) the device is attached to the the box does not interfere with or interrupt the grounding cover with at least two fasteners that are permanent (such continuity. as a rivet)or have a thread locking or screw locking means and(2)when the cover mounting holes are located on a flat (C) Metal Boxes. A connection shall be made between the non-raised portion of the cover. one or more equipment grounding conductors and a metal box by means of a grounding screw that shall be used for (B) Contact Devices or Yokes. Contact devices or yokes no other purpose, equipment listed for grounding, or a designed and listed as self-grounding shall be permitted listed grounding device. 2008 Edition NATIONAL ELECTRICAL CODE 70-119 250.160 ARTICLE 250—GROUNDING AND BONDING (D) Nonmetallic Boxes. One or more equipment ground- 250.166 Size of the Direct-Current Grounding Elec- ing conductors brought into a nonmetallic outlet box shall trode Conductor.The size of the grounding electrode con- be arranged such that a connection can be made to any ductor for a do system shall be as specified in 250.166(A) fitting or device in that box requiring grounding. and (B), except as permitted by 250.166(C) through (E). (E) Solder. Connections depending solely on solder shall (A) Not Smaller Than the Neutral Conductor. Where not be used. the do system consists of a 3-wire balancer set or a balancer winding with overcurrent protection as provided in 445.12(D), the grounding electrode conductor shall not be VIII. Direct-Current Systems smaller than the neutral conductor and not smaller than 250.160 General. Direct-current systems shall comply 8 AWG copper or 6 AWG aluminum. with Part VIII and other sections of Article 250 not specifi- cally intended for ac systems. (B) Not Smaller Than the Largest Conductor:Where the do system is other than as in 250.166(A), the grounding 250.162 Direct-Current Circuits and Systems to Be electrode conductor shall not be smaller than the largest Grounded. Direct-current circuits and systems shall be conductor supplied by the system, and not smaller than grounded as provided for in 250.162(A) and (B). 8 AWG copper or 6 AWG aluminum. (A) Two-Wire, Direct-Current Systems. A 2-wire, do (C) Connected to Rod,Pipe, or Plate Electrodes.Where connected to rod, pipe, or plate electrodes as in system supplying premises wiring and operating at greater 250.52(A)(5) or (A)(7), that portion of the grounding elec- than volts but not greater than 300 volts shall be trode conductor that is the sole connection to the grounding grounddee d, electrode shall not be required to be larger than 6 AWG Exception No. 1: A system equipped with a ground detec- copper wire or 4 AWG aluminum wire. for and supplying only industrial equipment in limited ar- eas shall not be required to be grounded. {D} Connected to aConcrete-Encased Electrode. Where connected to a concrete-encased electrode as in 250.52(A)(3), Exception No. 2: A rectifier-derived do system supplied that portion of the grounding electrode conductor that is the from an ac .system complving with 250.20 shall not be re- sole connection to the grounding electrode shall not be re- quired to be grounded. quired to be larger than 4 AWG copper wire. Exception No. 3: Direct-current fire alarm circuits having a maximum current of 0.030 ampere as specified in Article (E) Connected to a Ground Ring. Where connected to a 760, Part III, shall not be required to be grounded. ground ring as in 250.52(A)(4), that portion of the ground- ing electrode conductor that is the sole connection to the (B) Three-Wire, Direct-Current Systems. The neutral grounding electrode shall not be required to be larger than conductor of all 3-wire,do systems supplying premises wir- the conductor used for the ground ring, ing shall be grounded. 250.168 Direct-Current System Bonding Jumper. For 250.164 Point of Connection for Direct-Current Sys- direct-current systems that are to be grounded,an unspliced tems. bonding ;jumper shall be used to connect the equipment grounding conductor(s) to the grounded conductor at the (A) Off Prenuses Source. Direct-current systems to be source or khe first system disconnecting means where the grounded and supplied from an off-premises source shall system, is grounded. The size of the banding jumper shall have the grounding connection made at one or more supply not be smaller than the system grounding electrode cvnduc- stations. Agrounding connection shall not be made at indi- vidual for specified in 250.166 and shall comply with the provi- sions of 250.28(A), (B), and (C). (B) On-Premises Source. Where the do system source is 250.169 Ungrounded Direct-Current Separately Re- located on the premises, a grounding connection shall be rived Systems.Except as otherwise permitted in 250.34 for made at one of the following: portable and vehicle-mounted generators, an ungrounded (1) The source do separately derived system supplied from a stand-alone (2) The first system disconnection means or overcurrent power source(such as an engine-generator set)shall have a device grounding electrode conductor connected to an electrode (3) By other means that accomplish equivalent system pro- that complies with Part III of this article to provide for tection and that utilize equipment listed and identified grounding of metal enclosures, raceways, cables, and ex- for the use posed non-current-carrying metal parts of equipment. The 70-120 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 250—GROUNDING AND BONDING 250.184 grounding electrode conductor connection shall be to the boards having exposed live parts on the front of panels metal enclosure at any point on the separately derived sys- shall not have their cases connected to the equipment tem from the source to the first system disconnecting means grounding conductor. Mats of insulating rubber or other or overcurrent device, or it shall be made at the source of a suitable floor insulation shall be provided for the operator separately derived system that has no disconnecting means where the voltage to ground exceeds 150. or overcurrent devices. The size of the grounding electrode conductor shall be 250.176 Cases of Instruments, Meters, and Relays — in accordance with 250.166. Operating Voltage 1 kV and Over. Where instruments, meters, and relays have current-carrying parts of 1 kV and over to ground, they shall be isolated by elevation or pro- tected by suitable barriers, grounded metal, or insulating 250.170 Instrument Transformer Circuits. Secondary covers or guards. Their cases shall not be connected to the circuits of current and potential instrument transformers equipment grounding conductor. shall be grounded where the primary windings are con- Exce p tion: Cases of electrostatic ground detectors where netted to circuits of 300 volts or more to ground and,where the internal ground segments of the instrument care con- on switchboards, shall be grounded irrespective of voltage. nected to the instrument cave and grounded and the ground Exception No. 1: Circuits where the primary windings are detector is isolated by elevation. connected to circuits of less than 1000 volts with no live parts or wiring exposed or accessible to other than quali- 250.17$ Instrument Grounding Conductor. The equip- fed persons. m.ent grounding conductor for secondary circuits of instru- ment transformers and for instrument cases shall not be Exception No. 2: Current transformer secondaries con- smaller than 12 AWG copper or 10 AWG aluminum. Cases nected in a three-phase delta configuration shah not be of instrument transformers, instruments, meters, and relays required to be grounded that are mounted directly on grounded metal surfaces of 250.172 Instrument Transformer Cases.Cases or frames enclosures or grounded metal switchboard panels shall be of instrument transformers shall be connected to the equip- considered to be grounded, and no additional equipment grounding conductor shall be required. ment grounding conductor where accessible to other than qualified persons. Exception: Cases or frames of current transformers, the X. Grounding of Systems and Circuits of 1 kV and Over (High Voltage) primaries of which are not over 150 volts to ground and that are used exclusively to supply current to meters. 250.180 General. Where high-voltage systems are grounded, they shall comply with all applicable provisions 250.174 Cases of instruments, Meters, and Relays Op- of the preceding sections of this article and with 250.182 erating at Less Than 1000 Volts. Instruments, meters, and through 250.190,which supplement and modify the preced- relays operating with windings or working parts at less than ing sections. 1000 volts shall be connected to the equipment grounding conductor as specified in 250.174(A), (B), or (C). 250.182 Derived Neutral Systems.A system neutral point derived from a grounding transformer shall be permitted to (A) Not on Switchboards. Instruments, meters, and relays be used for grounding high-voltage systems. not located on switchboards, operating with windings or working parts at 300 volts or more to ground, and acces- 250.154 Solidly Grounded Neutral Systems. Solidly sible to other than qualified persons, shall have the cases grounded neutral systems shall be permitted to be either and other exposed metal parts connected to the equipment single point grounded or multigrounded neutral, grounding conductor. (A) Neutral Conductor. (B) On Dead-Front Switchboards. Instruments, meters, and relays (whether operated from current and potential trans- (1) Insulation Level.The minimum insulation level for neu- formers or connected directly in the circuit) on switchboards tral conductors of solidly grounded systems shall be 600 volts. having no live parts on the front of the panels shall have the Exception No. 1: Bare copper conductors shall be permit- cases connected to the equipment grounding conductor. ted to be used for the neutral conductor of the following: (C) On Live-Front Switchboards. Instruments, meters, (1) Service-entrance conductors and relays (whether operated from current and potential (2) Service laterals transformers or connected directly in the circuit) on switch- (3) Direct-buried portions of feeders. 2008 Edition NATIONAL ELECTRICAL CODE 70-121 2511.186 ARTICLE 250—GROUNDING AND BONDING Exception No, 2: Bart conductors shall be permitted for b. Underground circuits where the neutral conductor is the neutral conductor of overhead portions installed exposed outdoors, c. Overhead circuits installed outdoors Exception No. 3: The grounded neutral conductor shall be (2) The multigrounded neutral conductor shall be grounded permhted to be a bale conductor if isolated front phase at each transformer and at other additional locations by conductors and protected from phtisical dantage. connection to a grounding electrode. FPN: See 225.4 for conductor covering where within 3.0 m (3) At least one grounding electrode shall be installed and (10 ft) of any building or other structure. connected to the multigrounded neutral conductor ev- (2) Ampacity. The neutral conductor shall be of sufficient ery 400 m (1300 ft). ampacity for the load imposed on the conductor but not less (4) The maximum distance between any two adjacent elec- than 331/3 percent of the ampacity of the phase conductors. trodes shall not be more than 400 m (1300 ft). Exception: In industrial and commercial premises under (5) In a multigrounded shielded cable system, the shielding engineering supervision, it.shall be permissible to size the shall be grounded at each cable joint that is exposed to ampacity of the neutral conductor to not less than 20 per- personnel contact. cent ()J'the ampacity' of the phase conductor. 250,186 Impedance Grounded Neutral Systems. Imped- (B) Single-Point Grounded Neutral System. Where a ance grounded neutral systems in which a grounding imped- single-point grounded neutral system is used, the following ance,usually a resistor,limits the ground-fault current shall be shall apply: permitted where all of the following conditions are met: (1) A single-point grounded neutral system shall be permit- (1) The conditions of maintenance and supervision ensure ted to be supplied from (a) or (b): that only qualified persons service the installation. a. A separately derived system (2) Ground detectors are installed on the system. b. A multigrounded neutral system with an equipment (3) Line-to-neutral loads are not served, grounding conductor connected to the multi- grounded neutral conductor at the source of the Impedance grounded neutral systems shall comply with the provisions of 250.186(A) through (D). single-point grounded neutral system (2) A grounding electrode shall be provided for the system. (A) Location. The grounding impedance shall be inserted (3) A grounding electrode conductor shall connect the in the grounding conductor between the grounding elec- grounding electrode to the system neutral conductor. trode of the supply system and the neutral point of the (4) A bonding jumper shall connect the equipment ground- supply transformer or generator. ing conductor to the grounding electrode conductor. (S} An equipment grounding conductor shall be provided (B) Identified and Insulated.The neutral conductor of an impedance grounded neutral system shall be identified, as to each building, structure, and equipment enclosure. well as fully insulated with the same insulation as the phase (6) A neutral conductor shall only be required where conductors. phase-to-neutral loads are supplied. (7) The neutral conductor, where provided, shall he insu- (C) System Neutral Conductor Connection. The system Wed and isolated from earth except at one location. neutral conductor shall not be connected to ground, except (8) An equipment grounding conductor shall be run with through the neutral grounding impedance. the phase conductors and shall comply with (a), (b), (D) Equipment Grounding Conductors. Equipment and (c): grounding conductors shall be permitted to be bare and a. Shall not carry continuous load shall be electrically connected to the ground bus and b. May be bare or insulated grounding electrode conductor. c. Shall have sufficient ampacity for fault current duty (C) Multigrounded Neutral Systems. Where a multi- 250.188 Grounding of Systems Supplying Portable or rounded neutrals Stem is used, the following shall apply: Mobile Equipment. Systems supplying portable or mobile f< y g pp yl (I) The neutral conductor of a solidly grounded neutral high-voltage equipment, other than substations installed on a temporary basis, shall comply with 250.188(A) through (F). system shall be permitted to be grounded at more than one point. Grounding shall be permitted at one or more (A) Portable or Mobile Equipment. Portable or mobile of the following locations: high-voltage equipment shall be supplied from a system a. Transformers supplying conductors to a building or having its neutral conductor grounded through an imped- other structure ance. Where a delta-connected high-voltage system is used 70-122 NATIONAL ELECTRICAL CODE MIS Edition ARTICLE 280 SURGE ARRESTERS.OVER 1 kV W-5 to supply portable or mobile equipment, a system neutral point and associated neutral conductor shall be derived. ARTICLE 280 (B) Exposed Non-Current-Carrying Metal Parts. Ex- Surge Arresters, Over I kV posed non—current-carrying metal parts of portable or mo- bile equipment shall be connected by an equipment ground- 1. General ing conductor to the point at which the system neutral 280.1 Scope.This article covers general requirements,instal- impedance is grounded. lation requirements, and connection requirements for surge (C) Ground-Fault Current. The voltage developed be- Nesters installed on premises wiring systems over I kV. tween the portable or mobile equipment frame and ground 280.2 Uses Not Permitted. A surge arrester shall not be by the flow of maximum ground-fault current shall not installed where the rating of the surge arrester is less than exceed 100 volts. the maximum continuous phase-to-ground power frequency (D) Ground-Fault Detection and Relaying. Ground-fault voltage available at the point of application. detection and relaying shall be provided to automatically 280.3 Number Required. Where used at a point on a cir- de-energize any high-voltage system component that has cuit, a surge arrester shall be connected to each ungrounded developed a ground fault. The continuity of the equipment conductor.A single installation of such surge arresters shall grounding conductor shall be continuously monitored so as be permitted to protect a number of interconnected circuits, to de-energize automatically the high-voltage circuit to the provided that no circuit is exposed to surges while discon- portable or mobile equipment upon loss of continuity of the netted from the surge arresters. equipment grounding conductor. 280.4 Surge Arrester Selection. The surge arresters Shall (E) Isolation. The grounding electrode to which the por- comply with 280.4(A) and (B). table or mobile equipment system neutral impedance is connected shall be isolated from and separated in the (A) Rating.The rating of a surge arrester shall be equal to ground by at least 6.0 m (20 ft) from any other system or or greater than the maximum:continuous operating voltage equipment grounding electrode, and there shall be no direct available at the point of application. connection between the grounding electrodes, such as bur- (1) Solidi Grounded Solidly Systems.The maximum continuous ied pipe and fence, and so forth. Operating voltage shall be the phase-to-ground voltage of (F) Trailing Cable and Couplers. High-voltage trailing the System. cable and couplers for interconnection of portable or mo- (2) Impedance or Ungrounded System. The maximum bile equipment shall meet the requirements of Part III of continuous operating voltage shall be the phase-to-phase Article 400 for cables and 490.55 for couplers. voltage of the system. 250.190 Grounding of Equipment. All non—current- (B) Silicon Carbide Types. The rating of a silicon carrying metal parts of fixed, portable, and mobile equip- carbide-type surge arrester shall be not less than 125 per- ment and associated fences, housings, enclosures, and sup- cent of the rating specified in 280.4(A). porting structures shall be grounded. FPN No. 1: For further information on surge arresters,see ANSbgEEE C62.11-2005, Standard for Metal-Oxide Surge Exception: Where isolated from ground and located so as Arresters for Alternating-Current Power Circuits(>I kV), to prevent any person who can make contact with ground and ANSI/IEEE C62.22-1997, Guide for the Application of from contacting such metal parts when the equipment is Metal-Oxide Surge Arresters for Alternating-Current energized. Systems. FPN No. 2: The selection of a properly rated metal oxide Equipment grounding conductors not an integral part of arrester is based on considerations of maximum continuous a cable assembly shall not be smaller than 6 AWG copper operating voltage and the magnitude and duration of over- or 4 AWG aluminum. voltages at the arrester location as affected by phase-to- ground faults, system grounding techniques, switching FPN: See 250.110,Exception No. 2,for pole-mounted dis- surges, and other causes. See the manufacturer's applica- tribution apparatus. tion rules for selection of the specific arrester to be used at a particular location. 280.5 Listing, A surge arrester shall be a listed device. 2008 Edition NATIONAL.ELECTRICAL CODE 70-123 280.11 ARTICLE 285—SURGE-PROTECTIVE DEVICES(SPDs), I kV OR LESS II. Installation (B) Through Spark Gap or Device. Where the surge ar- rester grounding conductor is not connected as in 280.11 Location. Surge arresters shall be permitted to be 280.24(A) or where the secondary is not grounded as in located indoors or outdoors. Surge arresters shall be made 280.24(A} but is otherwise grounded as in 250.52, an inter- inaccessible unqualified persons, unless listed for instal- connection shall be made through a spark gap or listed lation in accessible locations. device as required by (B)(1) or (B)(2): 280.12 Routing of Surge Arrester Grounding Conduc- (1) Ungrounded or Ungrounded Primary System. For tors. The conductor used to connect the surge arrester to ungrounded or unggrounded primary systems, the spark gap line, bus, or equipment and to a grounding conductor con- or listed device shall have a 60-Hz breakdown voltage of at nection point as provided in 280.21 shall not be any longer least twice the primary circuit voltage but not necessarily than necessary and shall avoid unnecessary bends. more than 10 kV, and there shall be at least one other ground on the grounded conductor of the secondary that is III. Connecting Surge Arresters not less than 6.0 m (20 ft) distant from the surge-arrester grounding electrode. 280.21 Connection. The arrester grounding conductor shall be connected to one of the following: (2) Multigrounded Neutral Primary System. For multi- (1) Grounded service conductor grounded neutral primary systems, the spark gap or listed device shall have a 60-Hz breakdown of not more than 3 kV, (2) Grounding electrode conductor and there shall be at least one other ground on the grounded (3) Grounding electrode for the service conductor of the secondary that is not less than 6.0 m (20 ft) (4) Equipment grounding terminal in the service equipment distant from the surge-arrester grounding electrode. • 280.23 Surge-Arrester Conductors. The conductor be- (C) By Special Permission. An interconnection of the tween the surge arrester and the line and the surge arrester surge-arrester ground and the secondary neutral conductor, and the grounding connection shall not be smaller than other than as provided in 280.24(A) or(B), shall be permit- 6 AWG copper or aluminum. ted to be made only by special permission. 280.24 Interconnections. The grounding conductor of a 280.25 Grounding Conductor Connections and Enclo- surge arrester protecting a transformer that supplies a sec- s • Except as indicated in this article, surge-arrester ondary distribution system shall be interconnected as speci- grounding conductor connections shall be made as speci- fied in 280.24(A), (B), or (C). fied in Article 250, Parts III and X. Grounding conductors installed in metal enclosures shall comply with 250.64(E). (A) Metallic Interconnections. A metallic interconnection shall be made to the secondary grounded circuit conductor or the secondary circuit grounding conductor provided that, in addition to the direct grounding connection at the surge ARTICLE 285 arrester, the following occurs: 1 Surge-Protective Devices (SPDs), (1) Additional Grounding Connection. The grounded I kV or Less conductor of the secondary has elsewhere a grounding con- nection to a continuous metal underground water piping system. In urban water-pipe areas where there are at least 1. General four water-pipe connections on the neutral conductor and 285.1 Scope. This article covers general requirements, in- not fewer than four such connections in each mile of neu- stallation requirements, and connection requirements for tral conductor, the metallic interconnection shall be permit- SPDS (surge arresters and transient voltage surge suppres- ted to be made to the secondary neutral conductor with sots (TVSSs)] permanently installed on premises wiring omission of the direct grounding connection at the surge Systems 1 kV or less. arrester. FPN No. 1: Surge arresters less than l kV are also known (2) Multigrounded Neutral System Connection, The as Type 1 SPDS. grounded conductor of the secondary system is a part of a FPN No. 2: Transient voltage surge suppressors (TVSSs) multigrounded neutral system or static wire of which the are also known as Type 2 and Type 3 SPDS. primary neutral conductor or static wire has at least four • grounding connections in each mile of line in addition to a 285.3 Uses Not Permitted. An SPD (Surge arrester or grounding connection at each service. TVSS) device shall not be installed in the following: 70--124 RATIONAL ELECTRICAL CODE MIX Edition ARTICLE 285—SURGE-PROTECTIVE DEVICES(SPDs), 1 kV OR LESS 285,28 (1) Circuits exceeding 1 kV (2) Type 1 SPDs (surge arresters) Shall be permitted to be (2) On ungrounded systems, impedance grounded systems, connected as specified in 285.24. or corner grounded delta systems unless listed specifi- cally for use on these systems. (B) At the Service.When installed at services,the ground. (3) Where the rating of the SPD (surge arrester or TVSS) mg conductor of aType 1 SPD shall be connected to one of is less than the maximum continuous phase-to-ground the following: power frequency voltage available at the point of (I) Grounded service conductor application (2) Grounding electrode conductor FPN: For further information on SPDs (TVSSs), see (3) Grounding electrode for the Service NENIA LS 1-1992, Standard for law Voltage Surge Sup- (4) Equipment grounding terminal in the service pression Devices. The selection of a properly rated SPD equipment (TVSS) is based on criteria such as maximum continuous operating voltage, the magnitude and duration of overvolt- ages at the suppressor location as affected by phase-to- 285.24 Type 2 SPDs (TVSSs).Type 2 SPDs(TVSSs)shall ground faults, system grounding techniques,and switching be installed in accordance with 285.24(A)through(C). surges. (A) Service-Supplied Building or Structure. Type 2 285.4 Number Required. Where used at a point on a cir- SPDS (TVSSs) shall be connected anywhere on the load to the SPD (surge arrester or TVSS) shall be connected side of a service disconnect overcurrent device required in to each ungrounded conductor. 230.91, unless installed in accordance with 230.82(8). 285.5 Listing.An SPD(surge arrester or TVSS) shall be a (B) Feeder-Supplied Building or Structure.Type 2 SPDs listed device. (TVSSs) shall be connected at the building or structure 285.6 Short-Circuit Current Rating. The SPD (surge ar- anywhere on the load side of the first overcurrent device at rester or TVSS)shall be marked with a short-circuit current the building or structure. rating and shall not be installed at a point on the system where the available fault current is in excess of that rating. (C) Separately Derived System. The SPD (TVSS) shall This marking requirement shall not apply to receptacles, be connected on the load side of the first overcurrent device in a separately derived system. II. Installation 285.25 Type 3 SPDs. Type 3 SPDs (TVSSs) shall be per- 285.11 Location.SPDs(Surge arresters or TVSSs)shall be mitted to be installed anywhere on the load side of branch- permitted to be located indoors or outdoors and shall be circuit over-current protection up to the equipment served, made inaccessible to unqualified persons, unless listed for provided the connection is a nunimum 10 m (30 ft) of installation in accessible locations. conductor distance from the service or separately derived system disconnect. 285.12 Routing of Connections. The conductors used to connect the SPD(surge arrester or TVSS)to the line or bus 285.26 Conductor Size. Line and grounding conductors and to ground shall not be any longer than necessary and shall not be smaller than 14 AWG copper or 12 AWG shall avoid unnecessary bends. aluminum. III. Connecting SPDs. 285.27 Connection Between Conductors. An SPD (surge arrester or TVSS) shall be permitted to be connected be- 285.21 Connection. Where an SPD (surge arrester or tween any two conductors — ungrounded conductor(s), TVSS) device is installed, it shall comply with 285.23 grounded conductor, grounding conductor. The grounded through 285.28. conductor and the grounding conductor shall be intercon- 285,23 Type 1 SPDs (Surge Arresters). Type I SPDs nected only by the normal operation of the SPD (surge shall be installed in accordance with 285.23(A) and(B). arrester or TVSS) during a surge. (A) Installation. Type I SPDs (surge arresters) shall be 285.28 Grounding Conductor Connections and Enclo- installed as follows: sures. Except as indicated in this article, SPI) grounding (1) Type 1 SPDs (surge arresters) shall be permitted to be connections shall be made as specified in Article 250, 'Part connected to the supply side of the service disconnect 111. Grounding conductors installed in metal enclosures as permitted in 230.82(4) or shall comply with 250.64(E). 2008 Edition NATIONAL ELECTRICAL CODE 70-125 CHAPTER 3 ARTICLE 300—WIRING METHODS Chapter 3 Wiring Methods and Materials 300.3 Conductors. ARTICLE 300 (A) Single Conductors. Single conductors specified in Wiring Methods Table 310.13(A) shall only be installed where part of a recognized wiring method of Chapter 3. I. General Requirements Exception: Individual conchtctors shall be pennitted where installed as separate overhead conductors in accordance 300.1 Scope. with 225.6. (A) All Wiring Installations. This article covers wiring (B) Conductors of the Same Circuit. All conductors of methods for all wiring installations unless modified by the same circuit and, where used, the grounded conductor other articles. and all equipment grounding conductors and bonding con- (B) Integral Parts of Equipment. The provisions of this ductors shall be contained within the same raceway, auxil- article are not intended to apply to the conductors that form iary gutter, cable tray, cablebus assembly, trench, cable, or an integral part of equipment, such as motors, controllers, cord, unless otherwise permitted in accordance with motor control centers, or factory assembled control equip- ment or listed utilization equipment. (1) Paralleled Installations. Conductors shall be permit- ted to be run in parallel in accordance with the provisions (C) Metric Designators and Trade Sizes.Metric designa- of 310.4. The requirement to run all circuit conductors tors and trade sizes for conduit, tubing, and associated fit- within the same raceway, auxiliary gutter, cable tray, tings and accessories shall be as designated in Table trench, cable, or cord shall apply separately to each portion 300.1(C). of the paralleled installation, and the equipment grounding conductors shall comply with the provisions of 250.122. Table 300.1iC) Metric Designators and Trade Sizes Parallel runs in cable tray shall comply with the provisions o Metric Trade f 392.8(D). Designator Size Exception: Conductors installed in nonmetallic raceways run underground.shall he permitted to be arranged as iso- 16 12 ;x fated phase installations. The raceways shall be installed in 21 /a close proximih; and the conductors shall comphy with the 27 1 provisions of 300.20($). 35 1'A 41 P/2 (2) Grounding and Bonding Conductors. Equipment 53 2 grounding conductors shall be permitted to be installed out- 63 21/ side a raceway or cable assembly where in accordance with 78 3 the provisions of 250.130(C) for certain existing installa- 91 31/ tions or in accordance with 250.134(B), Exception No. 2, 103 4 129 5 for do circuits. Equipment bonding conductors shall be per- 155 6 mitted to be installed on the outside of raceways in accor- dance with 250.102(E). Note: The metric designators and trade sizes are for identilication purposes only and are not actual dimensions. (3) Nonferrous Wiring Methods. Conductors in wiring methods with a nonmetallic or other nonmagnetic sheath, 300.2 Limitations. where run in different raceways, auxiliary gutters, cable trays, trenches, cables, or cords, shall comply with the pro- (A) Voltage. Wiring methods specified in Chapter 3 shall visions of 300.20(B). Conductors in single-conductor Type be used for 600 volts, nominal, or less where not specifi- MI cable with a nonmagnetic sheath shall comply with the cally limited in some section of Chapter 3. They shall be provisions of 332.31. Conductors of single-conductor Type permitted for over 600 volts, nominal, where specifically MC cable with a nonmagnetic sheath shall comply with the permitted elsewhere in this Code. provisions of 330.31, 330.116, and 300.20(B). (B) Temperature. Temperature limitation of conductors (4) Enclosures. Where an auxiliary gutter runs between a shall be in accordance with 310.10. column-width panelboard and a pull box, and the pull box 74-126 NATIONAL ELECTRICAL CODE 2(X)6 Edition ARTICLE 300—WIRING METHODS 300.4 includes neutral terminations, the neutral conductors of cir- through bored holes in joists, rafters, or wood members, cuits supplied from the panelboard shall be permitted to holes shall be bored so that the edge of the hole is not less originate in the pull box. than 32 mm (11/a in.) from the nearest edge of the wood member. Where this distance cannot be maintained, the (C) Conductors of Different Systems. cable or raceway shall be protected from penetration by (1) 600 Volts, Nominal, or Less. Conductors of ac and de screws or nails by a steel plate(s) or bushing(s), at least circuits,rated 600 volts, nominal,or less, shall be permitted 1.6 mm ('ilb in.) thick, and of appropriate length and width to occupy the same equipment wiring enclosure, cable, or installed to cover the area of the wiring. raceway. All conductors shall have an insulation rating Exception No. 1: Steel plates shall not be required to pro- equal to at least the maximum circuit voltage applied to any tect rigid metal conduit, intermediate metal conduit, rigid conductor within the enclosure, cable, or raceway. nonmetallic conduit, or electrical metallic tubing. Exception: For solar photovoltaic systems in accordance Exception No. 2: A listed and marked steel plate less than with 690.4(B). 1.6 min (06 in.) thick that provides equal or better protec- tion against nail or screw penetration shall be permitted. FPN: See 725.136(A) for Class 2 and Class 3 circuit conductors. (2) Notches in Wood. Where there is no objection because of weakening the building structure, in both exposed and (2) Over 600 Volts, Nominal. Conductors of circuits rated concealed locations, cables or raceways shalt be permitted over 600 volts, nominal, shall not occupy the same equip- to be laid in notches in wood studs,joists, rafters, or other ment wiring enclosure, cable, or raceway with conductors wood members where the cable or raceway at those points of circuits rated 600 volts, nominal,or less unless otherwise is protected against nails or screws by a steel plate at least permitted in (C)(2)(a) through (C)(2)(e). 1.6 mm (1/le in.) thick, and of appropriate length and width, (a) Secondary wiring to electric-discharge lamps of 1000 installed to cover the area of the wiring. The steel plate volts or less, if insulated for the secondary voltage involved, shall be installed before the building finish is applied. shall be permitted to occupy the same luminaire, sign, or out- Exception No. 1: Steel plates shall not be required to pra- line lighting enclosure as the branch-circuit conductors. tect rigid metal conduit, intermediate metal conduit, rigid (b) Primary leads of electric-discharge lamp ballasts in- nonmetallic conduit, or electrical metallic tubing, sulated for the primary voltage of the ballast, where con- tained within the individual wiring enclosure, shall be per- Exception No. 2: A listed and marked steel plate less than mitted to occupy the same luminaire, sign, or outline 1.6 min (11m in.) thick that provides equal or better prorec- lighting enclosure as the branch-circuit conductors. tion against nail or screw penetration shall be permitted. (c) Excitation, control, relay, and ammeter conductors (g) Nonmetallic-Sheathed Cables and Electrical Non- used in connection with any individual motor or starter shall be permitted to occupy the same enclosure as the metallic Tubing Through Metal Fronting Members. motor-circuit conductors. (1) Nonmetallic-Sheathed Cable. In both exposed and (d) In motors, switchgear and control assemblies, and concealed locations where nonmetallic-sheathed cables similar equipment, conductors of different voltage ratings pass through either factory- or field-punched, cut, or drilled shall be permitted, slots or holes in metal members, the cable shall be pro- (e) In manholes, if the conductors of each system are tected by listed bushings or listed grommets covering all permanently and effectively separated from the conductors metal edges that are securely fastened in the opening prior of the other systems and securely fastened to racks, insula- to installation of the cable. tors, or other approved supports, conductors of different voltage ratings shall be permitted. (2) Nonmetallic-Sheathed Cable and Electrical Nonme- tallic TVbing. Where nails or screws are likely to penetrate Conductors having nonshielded insulation and operat- nonmetallic-sheathed cable or electrical nonmetallic tubing, ing at different voltage Ievels shall not occupy the same a steel sleeve, steel plate, or steel clip not less than 1.6 mm enclosure, cable, or raceway. (t/16 in.) in thickness shall be used to protect the cable or tubing. 300.4 Protection Against Physical Damage. Where sub- ject to physical damage, conductors shall be protected. Exception: A listed and marked steel plate less than 1.6 mm (06 in.) thick that provides equal or better protec- (A) Cables and Raceways Through Wood Members. tion against nail or screw penetration shall be permitted. (1) Bored Holes. In both exposed and concealed locations, (C) Cables Through Spaces Behind Panels Designed to where a cable- or raceway-type wiring method is installed Allow Access. Cables or raceway-type wiring methods, 2008 Edition NATIONAL ELECTRICAL CODE 70-127 300.5 ARTICLE 3W—WIRING METHODS installed behind panels designed to allow access, shall be Exception No. 2: A listed and marked.steel plate less than supported according to their applicable articles. 1.6 mm (0t, in.) thick that provides equal or better protec- (D) Cables and Raceways Parallel to Framing Mem- tion against nail or screw penetration shall be permitted. bers and Furring Strips. In both exposed and concealed (G) Insulated Fittings. Where raceways contain 4 AWG locations, where a cable- or raceway-type wiring method is or larger insulated circuit conductors and these conductors installed parallel to framing members, such as joists, enter a cabinet, box, enclosure, or raceway, the conductors rafters, or studs, or is installed parallel to furring strips, the shall be protected by a substantial fitting providing a cable or raceway shall be installed and supported so that the smoothly rounded insulating surface, unless the conductors nearest outside surface of the cable or raceway is not less are separated from the fitting or raceway by substantial than 32 mm (1114 in.) from the nearest edge of the framing insulating material that is securely fastened in place. member or furring strips where nails or screws are likely to penetrate. Where this distance cannot be maintained, the Exception: Where threaded hubs or bosses that are an in- cable or raceway shall be protected from penetration by tegral part of a cabinet, box, enclosure, or raceway provide nails or screws by a steel plate,sleeve, or equivalent at least a srnoothll rounded or flared entry for conductors. 1.6 mm (1/tr, in.) thick. Conduit bushings constructed wholly of insulating ma- Exception No. 1: Steel plates, sleeves, or the equivalent terial shall not be used to secure a fitting or raceway. The shall not be required to protect rigid metal conduit, inter- insulating fitting or insulating material shall have a tem- mediate rnetal conduit, rigid nonmetallic conduit, or elec- perature rating not less than the insulation temperature rat- tric•al metallic tubing. ing of the installed conductors. Exception No. 2: For concealed work in finished buildings, 300.5 Underground installations. or finished panels for prefabricated buildings where such supporting is impracticable, it shall be permissible to fish (A) Minimum Cover Requirements. Direct-buried cable the cables between access paints. or conduit or other raceways shall be installed to meet the Exception No. 3: A listed and marked steel plate less than minimum cover requirements of Table 300.5. 1.6 mot (r/r(, in.) thick that provides equal or better protec- tion against nail or screw penetration shall be permitted. (B) Wet Locations.The interior of enclosures or raceways installed underground shall be considered to be a wet 1'oca- (E) Cables and Raceways Installed Under Roof Deck- tion. Insulated,conductors and cables installed in these:en- ing. A cable- or raceway-type wiring method, installed in closures or raceways in underground installations shall be exposed or concealed locations under metal-corrugated sheet listed for use in wet locations and shall comply with roof decking, shall be installed and supported so the nearest 310.8(G). Any connections or splices in an underground outside surface of the cable or raceway is not less than 38 mm installation shall be approved for wet locations. (1�i in.)from the nearest surface of the roof decking. (C) Underground Cables Under Buildings. Underground FPN: hoof decking material is often repaired or replaced cable installed under a building shall be in a raceway. after the initial raceway or cabling and roofing installation and may be penetrated by the screws or other mechanical devices designed to provide "hold down" strength of the (D} Protection From Damage. Direct-buried conductors waterproof membrane or roof insulating material. and cables shall be protected from damage in accordance with 300.5(D)(1) through (13)(4). Exception: Rigid metal conduit and intermediate metal conduit shall not be required to comply with 300.4(E). (1) Emerging from Grade. Direct-buried conductors and cables emerging from grade and specified in columns 1 and (F) Cables and Raceways installed in Shallow Grooves. 4 of Table 300.5 shall be protected by enclosures or race- Cable- or raceway-type wiring methods installed in a groove, ways extending from the minimum cover distance below to be covered by wallboard, siding, paneling, carpeting, or grade required by 300.5(A) to a point at least 2.5 m (8 ft) similar finish,shall be protected by 1.6 mm('/i6 in.)thick steel above finished grade. In no case shall the protection be plate,sleeve,or equivalent or by not less than 32-tom(11/4-in.) required to exceed 450 mm (18 in.) below finished grade. free space for the full length of the groove in which the cable or raceway is installed. (2) Conductors Entering Buildings. Conductors entering a building shall be protected to the point of entrance. Exception Nn. l: Steel plates, sleeves, or the equivalent shall not be required to protect rigid metal conduit, inter- (3) Service Conductors. Underground service conductors mediate metal conduit, rigid nonmetallic conduit, or elec- that are not encased in concrete and that are buried 450 mm trical metallic tubing. (18 in.) or more below grade shall have their location 70-128 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 300—WIRING METHODS 300.5 Table 300.5 Minimum Cover Requirements, 0 to 600 Volts, Nominal, Burial in Millimeters (Inches) Type of Wiring Method or Circuit Column 5 Circuits for Column 4 Control of Column 3 Residential Irrigation and Nonmetallic Branch Circuits Landscape Raceways Listed Rated 120 Volts or Lighting Limited for Direct Burial Less with GFCI to Not More Than Column 2 Without Protection and 30 Volts and Column 1 Rigid Metal Concrete Maximum Installed with Direct Burial Conduit or Encasement or Overcurrent Type OF or in Cables or Intermediate Other Approved Protection of 20 Other Identified Conductors Metal Conduit Raceways Amperes Cable or Raceway Location of Wiring Method or Circuit mm in. mm in. mm in. mm in, nun in. All locations not specified 600 24 150 6 450 18 300 12 150 6 below in trench below 50-mm (2-in.) 450 18 150 6 300 12 150 6 150 6 thick concrete or equivalent Under a building 0 0 0 0 0 0 0 0 0 0 (in raceway only) (in raceway only) (in raceway only) Under minimum of 102-mm 450 18 l00 4 100 4 150 6 150 6 (4-in.) thick concrete exterior slab with no vehicular traffic (direct burial) (direct burial) and the slab extending not 100 4 100 4 less than 152 mm (6 in.) beyond the underground (in raceway) (in raceway) installation Under streets, highways, roads, 600 24 600 24 600 24 600 24 600 24 alleys, driveways, and parking lots One- and two-family dwelling 450 18 450 18 450 18 300 12 450 18 driveways and outdoor parking areas, and used only for dwelling-related purposes In or under airport runways, 450 Is 450 18 450 18 450 18 450 Is including adjacent areas where trespassing prohibited Notes: 1. Cover is defined as the shortest distance in millimeters (inches) measured between a point on the top surface of any direct-buried conductor, cable,conduit,or other raceway and the top surface of finished grade,concrete, or similar cover. 2. Raceways approved for burial only where concrete encased shall require concrete envelope not less than 50 mm (2 in.) thick. 3. Lesser depths shall be permitted where cables and conductors rise for terminations or splices or where access is otherwise required. 4. Where one of the wiring method types listed in Columns 1-3 is used for one of the circuit types in Columns 4 and 5, the shallowest depth of burial shall he permitted. 5.Where solid rock prevents compliance with the cover depths specified in this table,the wiring shall be installed in metal or nonmetallic raceway permitted for direct burial.The raceways shall be covered by a minimum of 50 mm(2 in.) of concrete extending down to rock. 2008 Edition NATIONAL ELECTRICAL CODE 70-129 300.6 ARTICLE 300—WIRING METHODS identified by a warning ribbon that is placed in the trench at (J) Earth Movement. Where direct-buried conductors, least 300 mm (12 in.) above the underground installation. raceways, or cables are subject to movement by settlement or frost, direct-buried conductors, raceways, or cables shall (4) Enclosure or Raceway Damage. Where the enclosure be arranged so as to prevent damage to the enclosed con- or raceway is subject to physical damage, the conductors ductors or to equipment connected to the raceways. shall be installed in rigid metal conduit, intermediate metal conduit, Schedule 80 PVC conduit, or equivalent. FPN: This section recognizes "5" loops in underground direct burial to raceway transitions, expansion fittings in raceway risers to fixed equipment, and, generally, the pro- (E) Splices and Taps. Direct-buried conductors or cables vision of flexible connections to equipment subject to shall be permitted to be spliced or tapped without the use of settlement or frost heaves. splice boxes. The splices or taps shall be made in accor- dance with 110.14(B). (K) Directional Boring. Cables or raceways installed us- ing directional boring equipment shall be approved for the (F) Bacicfrll. Backfill that contains large rocks, paving ma- purpose. terials, cinders, large or sharply angular substances, or cor- rosive material shall not be placed in an excavation where 300.6 Protection Against Corrosion and Deterioration. materials may damage raceways, cables, or other substruc- Raceways, cable trays, cablebus, auxiliary gutters, cable tures or prevent adequate compaction of fill or contribute to armor, boxes, cable sheathing, cabinets, elbows, couplings, corrosion of raceways, cables, or other substructures, fittings, supports, and support hardware shall be of materi- Where necessary to prevent physical damage to the als suitable for the environment in which they are to be raceway or cable, protection shall be provided in the form installed. of granular or selected material, suitable running boards, suitable sleeves, or other approved means. (A) Ferrous Metal Equipment. Ferrous metal raceways, cable trays, cablebus, auxiliary gutters, cable armor, boxes, (G) Raceway Seals. Conduits or raceways through which cable sheathing,cabinets, metal elbows, couplings, nipples, moisture may contact live parts shall be sealed or plugged fittings, supports, and support hardware shall be suitably at either or both ends. protected against corrosion inside and outside (except threads at joints) by a coating of approved corrosion- FPN: Presence of hazardous gases or vapors may also ne- resistant material. Where corrosion protection is necessary cessitate sealing of underground conduits or raceways en- and the conduit is threaded in the field, the threads shall be tering buildings, coated with an approved electrically conductive, corrosion- (H) Bushing. A bushing, or terminal fitting, with an inte- resistant compound. gral bushed opening shall be used at the end of a conduit or Exception: Stainless steel shall not be required to have other raceway that terminates underground where the con- protective coatings. ductors or cables emerge as a direct burial wiring method. A sea] incorporating the physical protection characteristics (1) Protected from Corrosion Solely by Enamel. Where of a bushing shall be permitted to be used in lieu of a protected from corrosion solely by enamel, ferrous metal bushing. raceways, cable trays, cablebus, auxiliary gutters, cable ar- mor, boxes, cable sheathing, cabinets, metal elbows, cou- (I) Conductors of the Same Circuit. All conductors of plings, nipples, fittings, supports, and support hardware the same circuit and, where used, the grounded conductor shall not be used outdoors or in wet locations as described and all equipment grounding conductors shall be installed in 300.6(D). in the same raceway or cable or shall be installed in close (2) Organic Coatings on Boxes or Cabinets. Where proximity in the same trench. boxes or cabinets have an approved system of organic coat- Exception No. l: Conductors in parallel in raceways or ings and are marked "Raintight," "Rainproof," or"Outdoor cables shall be permitted, but each racewav or cable shall Type," they shall be permitted outdoors. contain all conductors of the same circuit including equip- (3) In Concrete or in Direct Contact with the Earth. ment grounding conductors. Ferrous metal raceways, cable armor, boxes, cable sheath- Exception No. 2: Isolated phase, polarity, grounded con- ing, cabinets, elbows, couplings, nipples, fittings, supports, doctor, and equipment grounding and bonding conductor and support hardware shall be permitted to be installed in installations shall be permitted in nonmetallic raceways or concrete or in direct contact with the earth, or in areas rubles with a nonmetallic covering or nonmagnetic sheath in subject to severe corrosive influences where made of mate- close pro.vimity where conductors are paralleled as permitted rial approved for the condition, or where provided with in 310.4, and Inhere the conditions of'300.20(B)are met. corrosion protection approved for the condition. 70-130 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 300—WIRING METHODS 300.11 (B) Aluminum Metal Equipment. Aluminum raceways, (B) Expansion Fittings. Raceways shall be provided with cable trays, cablebus, auxiliary gutters, cable armor, boxes, expansion fittings where necessary to compensate for ther- cable sheathing, cabinets, elbows, couplings, nipples, fit- mal expansion and contraction. tings,supports, and support hardware embedded or encased in concrete or in direct contact with the earth shall be pro- sign Table Lion for and Table 355.44 provide the for re- sion information for polyvinyl chloride (PVC) and for re- vided with supplementary corrosion protection. inforced thermosetting resin conduit(R'IRC),respectively. A nominal number for steel conduit can be determined by (C) Nonmetallic Equipment. Nonmetallic raceways, multiplying the expansion length in Table 352.44 by 0.20. cable trays,cablebus,auxiliary gutters,boxes,cables with a The coefficient of expansion for steel electrical metallic nonmetallic outer jacket and internal metal armor or jacket, tubing, intermediate metal conduit, and rigid conduit is cable sheathing, cabinets, elbows, couplings, nipples, fit- 1.170 x l0-5 (0.0000117 mm per mm of conduit for each tings, supports, and support hardware shall be made of ma- °C in temperature change) [0,650 X 10'5(0.0000065 in.per roved for the condition and shall comply with inch of conduit for each °F in temperature change)]. terial approved P Y A nominal number for aluminum conduit and alumi- (C)(1) and (C)(2) as applicable to the specific installation. num electrical metallic tubing can be determined by muld- plying the expansion length in Table 352.44 by 0.40.The (1) Exposed to Sunlight. Where exposed to sunlight, the coefficient of expansion for aluminum electrical metallic materials shall be listed as sunlight resistant or shall be tubing and aluminum rigid metal conduit is 2.34 x IT5 identified as sunlight resistant. (0.0000234 mm per mm of conduit for each°C in tempera- ture change) 1 1.30 x 10-5(0.000013)in.per mach of conduit (2) Chemical Exposure. Where subject to exposure to for each °F in temperature change}. chemical solvents, vapors, splashing, or immersion, mate- rials or coatings shall either be inherently resistant to 300.8 Installation of Conductors with Other Systems. chemicals based on their listing or be identified for the Raceways or cable trays containing electrical conductors specific chemical reagent. shall not contain any pipe, tube, or equal for steam, water, air, gas, drainage, or any service other than electrical. (D) Indoor Wet Locations.In portions of dairy processing facilities, laundries, canneries, and other indoor wet coca- 300.9 Raceways in Wet Locations Above Grade. Where tions, and in locations where walls are frequently washed or raceways are installed in wet Iocations abovegrade, the in- where there are surfaces of absorbent materials, such as terior of these raceways shall be considered to be a wet damp paper or wood, the entire wiring system, where in- location. Insulated conductors and cables installed in races stalled exposed, including all boxes, fittings, raceways, and ways in wet locations abovegrade Shall comply with cable used therewith, shall be mounted so that there is at 310.8(C). least a 6-n-tin ('f4-in.) airspace between it and the wail or supporting surface. 300.10 Electrical Continuity of Metal Raceways and Exception: Nonmetallic raceways, boxes, and fittings shall Enclosures. Metal raceways, cable armor, and other metal enclosures for conductors shall be metallically joined to- be permitted to be installed without the airspace on a con- gether into a continuous electrical conductor and shall be Crete, masonry, tile, or similar surface. connected to all boxes, fittings, and cabinets so as to pro- FPN: In general, areas where acids and alkali chemicals vide effective electrical continuity. Unless specifically per- are handled and stored may present such corrosive condi- mitted elsewhere in this Code, raceways and cable assem- tions,particularly when wet or damp.Severe corrosive con- blies shall be mechanically secured to boxes, fittings, ditions may also be present in portions of meatpacking cabinets, and other enclosures. plants, tanneries, glue houses, and some stables; in instal- lations immediately adjacent to a seashore and swimming Exception No. 1: Short sections of raceways used to pro- pool areas;in areas where chemical deicers are used;and in vide support or protection of cable assemblies from physi- storage cellars or rooms for hides, casings, fertilizer, salt, and bulk chemicals. cal damage shall not be required to be made electrically continuous. 300.7 Raceways Exposed to Different Temperatures. Exception No. 2: Equipment enclosures to be isolated, as (A) Sealing. Where portions of a cable raceway or sleeve permitted by 250.96(B), shall not be required to be metal- are known to be subjected to different temperatures and where lically joined to the metal raceway. condensation is known to be a problem, as in cold storage 300.11 Securing and Supporting. areas of buildings or where passing from the interior to the exterior of a building, the raceway or sleeve shall be filled (A) Secured in Place. Raceways, cable assemblies, boxes, with an approved material to prevent the circulation of warm cabinets, and fittings shall be securely fastened in place. air to a colder section of the raceway or sleeve.An explosion- Support wires that do not provide secure support shall not proof seal shall not be required for this purpose. be permitted as the sole support. Support wires and associ- 2006 Edition NATIONAL ELECTRICAL CODE 70-131 300.12 ARTICLE 30(1—WIRING METHODS aced fittings that provide secure support and that are in- cable sheaths shall be continuous between cabinets, boxes, stalled in addition to the ceiling grid support wires shall be fittings, or other enclosures or outlets. permitted as the sale support. Where independent support wires are used, they shall be secured at both ends. Cables Exception Nn. 1: Short sections of raceways used to pro- wires raceways shall not be supported by ceiling grids. vide support or protection of cable assemblies from physi- cal damage shall not he required to be mechanically (1) Fire-Rated Assemblies.Wiring located within the cav- continuous. ity of a fire-rated floor-ceiling or roof-ceiling assembly Exception No. 2: Raceways and cables installed into the shall not be secured to, or supported by, the ceiling assem- bottom of open bottom equipment, such as switchboards, bly, including the ceiling support wires. An independent motor control centers, and floor or pad-mounted transform- means of secure support shall be provided and shall be ers, shall not be required to be mechanically secured to the permitted to be attached to the assembly. Where indepen- equipment. dent support wires are used, they shall be distinguishable by color, tagging, or other effective means from those that 300.13 Mechanical and Electrical Continuity — Con- are part of the fire-rated design. ductors. Evc•eption: The ceiling support s-stem shall be permitted (A) General. Conductors in raceways shall be continuous to support wiring and equipment that have been tested as between outlets, boxes, devices,and so forth.There shall be port of the fire-rated assembly. no splice or tap within a raceway unless permitted by FPN: One method of determining fire rating is testing in 300.15, 368.56(A); 376.56; 378.56; 384.56; 386.56; accordance with NFPA 251-2006, Standard Methods of 388.56; or 390.6. Tests of Fire Resistance of Building Construction and Mate=rials. (B) Device Removal. In multiwire branch circuits, the (2) Non-Fire-Rated Assemblies. Wiring located within continuity of a grounded conductor shall not depend on the cavity of a non-fire-rated floor-ceiling or roof-ceiling device connections such as lampholders, receptacles, and assembly shall not be secured to, or supported by, the ceil- so forth, where the removal of such devices would interrupt ing assembly, including the ceiling support wires.An inde- the continuity. pendent means of secure support shall be provided and Shall be permitted to be attached to the assembly. 300.14 Length of Free Conductors at Outlets, Junc- tions, and Switch Points. At least 150 mm (6 in.) of free Exception: The ceiling support system shall be permitted conductor, measured from the point in the box where it to support branch-circuit wiring and associated equipment emerges from its raceway or cable sheath, shall be left at where installed in accordance with the ceiling s}•stets each outlet, junction, and switch point for splices or the manufarturer's- instructions. connection of luminaires or devices, Where the opening to (B) Raceways Used as Means of Support. Raceways an outlet, junction, or switch point is less than 200 mm shall be used only as a means of support for other race- (8 in.)in any dimension, each conductor shall be long enough ways, cables, or nonelectrical equipment under any of the to extend at least 75 mm (3 in.) outside the opening. following conditions: Exception: Conductors that are not spliced or terminated (1) Where the raceway or means of support is identified for at the outlet,junction, or switch point shall not be required the purpose to comply with 100.14. (2) Where the raceway contains power supply conductors for electrically controlled equipment and is used to sup- 300.15 Boxes,Conduit Bodies,or Fittings—Where Re- port Class 2 circuit conductors or cables that are solely quired. A box shall be installed at each outlet and switch for the purpose of connection to the equipment control point for concealed knob-and-tube wiring. circuits Fittings and connectors shall be used only with the spe- (3) Where the raceway is used to support boxes or conduit cific wiring methods for which they are designed and listed. bodies in accordance with 314.23 or to support lumi- Where the wiring method is conduit, tubing, Type AC naires in accordance with 410.36(E) cable, Type MC cable, Type MI cable, nonmetallic-sheathed cable,or other cables,a box or conduit body shall be installed (C) Cables Not Used as Means of Support. Cable wiring at each conductor splice point,outlet point,switch point,junc- methods shall not be used as a means of support for other tion point, termination point, or pull point, unless otherwise cables, raceways, or nonelectrical equipment. permitted in 300.15(A) through (M). 300.12 Mechanical Continuity — Raceways and (A) Wiring Methods with Interior Access. A box or con- Cables. Metal or nonmetallic raceways, cable armors, and duit body shall not be required for each splice, junction, 70-132 NATIONAL ELECTRICAL CODE 2009 Edition ARTICLE 300—WIRING METHODS 300.18 switch, pull, termination,or outlet points in wiring methods or handhole enclosures, except where connecting to electri- with removable covers, such as wireways, multioutlet as- cal equipment. The installation shall comply with the pro- semblies, auxiliary gutters, and surface raceways. The cov- visions of Part V of Article 110 for manholes, and 314.30 ers shall be accessible after installation. for handhole enclosures. (B) Equipment. An integral junction box or wiring com- (M) Closed Loop. A box shall not be required with a partment as part of approved equipment shall be permitted closed-loop power distribution system where a device in lieu of a box. identified and listed as suitable for installation without a box is used. (C) Protection. A box or conduit body shall not he re- quired where cables enter or exit from conduit or tubing 300.16 Raceway or Cable to Open or Concealed Wiring. that is used to provide cable support or protection against physical damage. A fitting shall be provided on the end(s) (A) Box, Conduit Body, or Fitting. A box, conduit body, of the conduit or tubing to protect the cable from abrasion. or terminal fitting having a separately bushed hole for each conductor shall be used wherever a change is made from (D) Type MI Cable. A box or conduit body shall not be conduit, electrical metallic tubing, electrical nonmetallic required where accessible fittings are used for straight- tubing, nonmetallic-sheathed cable, Type AC cable, Type through splices in mineral-insulated metal-sheathed cable. MC cable, or mineral-insulated, metal-sheathed cable and (E) Integral Enclosure. A wiring device with integral en- surface raceway wiring to open wiring or to concealed knob-and-tube wiring. A filling used for this purpose shall closure identified for the use, having brackets that securely contain no taps or splices and shall not be used at luminaire fasten the device to walls or ceilings of conventional on- outlets. A Conduit body used for this purpose Shall contain site Frame construction, far use with nonmetallic-sheathed no taps or splices, unless it complies With 31314.16(C)(2).cable, shall be permitted in lieu of a box or conduit body. FPN: See 334.30(C);545.10-,550-15(f);551.47(E), Excep- (B) Bushing.A bushing shall be permitted in lieu of a box tion No. 1; and 552.48(E), Exception No. 1. or terminal where the conductors emerge from a raceway and enter or terminate at equipment, such as open switch- (F) Fitting. A fitting identified for the use shall be permit- boards, unenclosed control equipment, or similar equip- ted in lieu of a box or conduit body where conductors are ment. The bushing shall be of the insulating type for other not spliced or terminated within the fitting.The fitting shall than lead-sheathed conductors. be accessible after installation. 300.17 Number and Size of Conductors in Raceway. (G) Direct-Buried Conductors.As permitted in 300.5(E), The number and size of conductors in any raceway shall a box or conduit body shall not be required for splices and not be more than will permit dissipation of the heat and taps in direct-buried conductors and cables. ready installation or withdrawal of the conductors without (H) Insulated Devices. As permitted in 334.40(B), a box damage to the conductors or to their insulation. or conduit body shall not be required for insulated devices FPN: See the following sections of this Code. intermediate supplied by nonmetallic-sheathed cable. metal conduit, 342.22; rigid metal conduit,344.22;flexible metal conduit, 348.22; liquidtight flexible metal conduit, (1) Enclosures. A box or conduit body shall not be re- 350.22; PVC conduit, 352.22; HDPE conduit, 353.22; quired where a splice, switch, terminal, or pull point is in a RTRC, 355.22; liquidtight nonmetallic flexible conduit, cabinet or cutout box, in an enclosure for a switch or over- 356.22; electrical metallic tubing, 358.22; flexible metallic tubing.360.22;electrical nonmetallic tubing,362.22;cellu- current device as permitted in 312.8, in a motor controller lar concrete floor raceways, 372.11; cellular metal floor as permitted in 430.10(A), or in a motor control center. raceways. 374.5; metal wireways, 376.22; nonmetallic wireways, 378.22; surface metal raceways, 386.22; surface (J) Luminaires. A box or conduit body shall not be re- nonmetallic raceways, 388.22; underfloor raceways, 390.5; quired where a luminaire is used as a raceway as permitted fixture wire,402.7;theaters,520.6;signs,600.31(C);eleva- in 410.64 and 410.65. tors, 620.33, audio signal processing,amplification,and re- production equipment, 640.23(A) and 640.24; Class 1, Class 2, and Class 3 circuits, Article 725; fire alarm cir- cuits, Article 760; and optical fiber cables and raceways, quired for splices where conductors are embedded as per- Article 770. mitted in 424.40, 424.4](D), 426.22(B), 426.24(A), and 427.19(A). 300.18 Raceway Installations. (L) Manholes and Handhole Enclosures. A box or con- (A) Complete Runs. Raceways,other than busways or ex- duit body shall not be required for conductors in manholes posed raceways having hinged or removable covers, shall 2008 Edition NATIONAL ELECTRICAL CODE 70_133 300.19 ARTICLE 300—WIRING METHODS be installed complete between outlet, junction, or splicing ing of the electrical circuit protective system used and in no points prior to the installation of conductors. Where re- case shall exceed the values in Table 300.19(A). quired to facilitate the installation of utilization equipment, the raceway shall be permitted to be initially installed with- (C) Support Methods. One of the following methods of out a terminating connection at the equipment. Prewired support shall be used: raceway assemblies shall be permitted only where specifi- (1) By clamping devices constructed of or employing insu- cally permitted in this Code for the applicable wiring lating wedges inserted in the ends of the raceways. method. Where clamping of insulation does not adequately sup- port the cable, the conductor also shall be clamped. Exception: Short sections of raceways used to contain rnn- ductors or cable assemblies for protection from physical (2) By inserting boxes at the required intervals in which da►nage .shall not be required to be installed complete be- insulating supports are installed and secured in a satis- tween nutlet,junction, or splicing points. factory manner to withstand the weight of the conduc- tors attached thereto, the boxes being provided with (B) Welding. Metal raceways shall not be supported, ter- covers. minated, or connected by welding to the raceway unless (3) Injunction boxes, by deflecting the cables not less than specifically designed to be or otherwise specifically permit- 90 degrees and carrying them horizontally to a distance ted to be in this Code. not less than twice the diameter of the cable, the cables being carried on two or more insulating supports and 300.19 Supporting Conductors in Vertical Raceways. additionally secured thereto by tie wires if desired. (A) Spacing Intervals — Maximum. Conductors in ver- Where this method is used,cables shall be supported at tical raceways shall be supported if the vertical rise exceeds intervals not greater than 20 percent of those mentioned the values in Table 300.19(A). One cable support shall be in the preceding tabulation. provided at the top of the vertical raceway or as close to the (4) By a method of equal effectiveness. top as practical. Intermediate supports shall be provided as necessary to limit supported conductor lengths to not 300.20 Induced Currents in Ferrous Metal Enclosures greater than those values specified in Table 300.19(A). or Ferrous Metal Raceways. Exception: Steel wire armor cable shall be supported at (A) Conductors Grouped Together. Where conductors the tap of the riser with a cable support that clamps the carrying alternating current are installed in ferrous metal steel wire armor, A safety device .shall be permitted at the enclosures or ferrous metal raceways, they shall be ar- loswer end of the riser to hold the cable in the event there is ranged so as to avoid heating the surrounding ferrous metal slippage of the cable in the wire-armored cable support. by induction. To accomplish this, all phase conductors and, Additional wee tqe-type supports shall be permitted to re- where used, the grounded conductor and all equipment lieve the strain on the equipment terminals caused by ex- grounding conductors shall be grouped together. pansinn of the cable tinder loud. Exception No. 1: Equipment grounding conductors for (B) Fire-Rated Cables and Conductors. Support meth- certain existing installations shall be permitted to be in- ods and spacing intervals for fire-rated cables and conduc- stalled separate from their associated circuit conductors tors shall comply with any restrictions provided in the Iist- where run in accordance with the provisions of 250.130(C). Table 300.19(A) Spacings for Conductor Supports Conductors Aluminum or Support of Copper-Clad Conductors in Aluminum Copper Vertical Size of Wire Raceways m ft m Ft 18 AWG through 8 AWG Not greater than 30 too 30 100 6 AWG through 1/0 AWG Not greater than 60 200 30 100 JO AWG through 4/0 AWG Not greater than 55 180 25 80 Over 4/0 AWG through 350 kemil Not greater than 41 135 18 60 Over 350 kcmil through 500 kcmil Not greater than 36 120 15 50 Over 500 kemil through 750 kcmil Not greater than 28 95 12 40 Over 750 kemil Not greater than 26 85 11 35 70-134 NATIONAL.ELECTRICAL CODE 2008 Edition ARTICLE 300—WIRING METHODS 300.22 Exception No. 2: A single conductor shall be permitted to shaft containing only such ducts,used for vapor removal or be installed in a ferromagnetic enclosure and used for skin- for ventilation of commercial-type cooking equipment. elect heating in accordance with the provisions of 426.42 and 427.47. (B) Ducts or Plenums Used for Environmental Air.Only wiring methods consisting of Type MI cable, Type MC (B) Individual Conductors. Where a single conductor cable employing a smooth or corrugated impervious metal carrying alternating current passes through metal with mag- sheath without an overall nonmetallic covering, electrical netic properties, the inductive effect shall be minimized by metallic tubing, flexible metallic tubing, intermediate metal (1) cutting slots in the metal between the individual holes conduit, or rigid metal conduit without an overall nonme- through which the individual conductors pass or(2)passing tallic covering shall be installed in ducts or plenums spe- all the conductors in the circuit through an insulating wall cifically fabricated to transport environmental air. Flexible sufficiently large for all of the conductors of the circuit. metal conduit shall be permitted, in lengths not to exceed 1.2 m (4 ft), to connect physically adjustable equipment Exception: In the case of circuits supplying vacuum or and devices permitted to be in these ducts and plenum electric-discharge lighting systems or signs or X-ray appa- chambers. The connectors used with flexible metal conduit rates, the currents carried by the conductors are so small shall effectively close any openings in the connection. that the inductive heating effect can be ignored where these Equipment and devices shall be permitted within such ducts conductors are placed in metal enclosures or pass through or plenum chambers only if necessary for their direct action ,petal. upon, or sensing of, the contained air. Where equipment or FPN: Because aluminum is not a magnetic metal, there devices are installed and illumination is necessary to facili- will be no heating due to hysteresis; however, induced cur- tate maintenance and repair, enclosed gasketed-type lumi- rents will be present.They will not be of sufficient magni- naires shall be permitted. tude to require grouping of conductors or special treatment in passing conductors through aluminum wall sections. (C) Other Space Used for Environmental Air. This sec- tion applies to space used for environmental air-handling 300.21 Spread of Fire or Products of Combustion. Elec- purposes other than ducts and plenums as specified in trical installations in hollow spaces, vertical shafts, and 300.22(A) and (B). It does not include habitable rooms or ventilation or air-handling ducts shall be made so that the areas of buildings, the prime purpose of which is not air possible spread of fire or products of combustion will not handling. be substantially increased. Openings around electrical pen- FPN: The space over a hung ceiling used for environmen- etrations through fire-resistant-rated walls, partitions, tal air-handling purposes is an example of the type of other floors,or ceilings shall be firestopped using approved meth- space to which this section applies. ods to maintain the fire resistance rating. Exception: This section shall not apply to the joist or stud FPN: Directories of electrical construction materials pub- spaces of dwelling units where the wiring passes through lished by qualified testing laboratories contain many listing such spaces perpendicular to the long dimension of such installation restrictions necessary to maintain the fire- spaces. resistive rating of assemblies where penetrations or open- ings are made. Building codes also contain restrictions on (1) Wiring Methods. The wiring methods for such other membrane penetrations on opposite sides of a fire- space shall be limited to totally enclosed, nonventiiated, resistance-rated wall assembly.An example is the 600-mm insulated busway having no provisions for plug-in connec- (24-in.) minimum horizontal separation that usually applies between boxes installed on opposite sides of the wall. As- tions, Type MI cable, Type MC cable without an overall sistance in complying with 300.21 can be found in building nonmetallic covering, Type AC cable, or other factory- codes, fire resistance directories, and product listings. assembled multiconductor control or power cable that is specifically listed for the use, or listed prefabricated cable 300.22 Wiring in Ducts, Plenums, and Other Air- assemblies of metallic manufactured wiring systems with- Handling Spaces. The provisions of this section apply to out nonmetallic sheath. Other types of cables, conductors, the installation and uses of electrical wiring and equipment and raceways shall be permitted to be installed in electrical in ducts, plenums, and other air-handling spaces. metallic tubing, flexible metallic tubing, intermediate metal conduit, rigid metal conduit without an overall nonmetallic FPN: See Article 424, Part VI, for duct heaters, covering, flexible metal conduit, or, where accessible, sur- face metal raceway or metal wireway with metal covers or {A} Ducts for Dust, Loose Stock, or Vapor Removal.No solid bottom metal cable tray with solid metal covers. wiring systems of any type shall be installed in ducts used to transport dust, loose stock, or flammable vapors. No (2) Equipment. Electrical equipment with a metal enclo- wiring system of any type shall be installed in any duct, or sure, or with a nonmetallic enclosure listed for the use and 2008 Edition NATIONAL ELECTRICAL CODE 70-135 300.23 ARTICLE AX)—WIRING METHODS having adequate fire-resistant and low-smoke-producing 300.39 Braid-Covered Insulated Conductors — Ex- characteristics, and associated wiring material suitable for posed Installation. Exposed runs of braid-covered insu- the ambient temperature shall be permitted to be installed Iated conductors shall have a flame-retardant braid. If the in such other space unless prohibited elsewhere in this conductors used do not have this protection, a flame- Code. retardant saturant shall be applied to the braid covering Exception: Integral full s_rstems shall be Permitted where after installation. This treated braid covering shall be specifically identified for such use. stripped back a safe distance at conductor terminals, ac- cording to the operating voltage. Where practicable, this (D) Information Technology Equipment, Electrical wir- distance shall not be less than 25 mm (1 in.) for each ing in air-handling areas beneath raised floors for informa- kilovolt of the conductor-to-ground voltage of the circuit. lion technology equipment shall be permitted in accordance with Article 645. 300.40 Insulation Shielding.Metallic and semiconducting insulation shielding components of shielded cables shall be removed for a distance dependent on the circuit voltage and 300.23 Panels Designed to Allow Access. Cables, race- insulation. Stress reduction means shall be provided at all ways, and equipment installed behind panels designed to terminations of factory-applied shielding. allow access, including suspended ceiling panels, shall be ]Metallic shielding components such as tapes, wires, or arranged and secured so as to allow the removal of panels braids, or combinations thereof, shall be connected to a and access to the equipment. grounding conductor, grounding busbar, or a grounding electrode. II. Requirements for over 600 Volts, Nominal 300.42 Moisture or Mechanical Protection for Metal- 300.31 Covers Required. Suitable covers shall be in- Sheathed Cables. Where cable conductors emerge from a stalled on all boxes, fittings, and similar enclosures to pre- metal sheath and where protection against moisture or vent accidental contact with energized parts or physical physical damage is necessary, the insulation of the condue- damage to parts or insulation. tors shall be protected by a cable sheath terminating device. 300.32 Conductors of Different Systems. See 300.3(C)(2). 300.50 Underground Installations. (A) General. Underground conductors shall be identified 300.34 Conductor Bending Radius. The conductor shall for the voltage and conditions under which they are in- not be bent to a radius less than 8 times the overall diameter stalled. Direct burial cables shall comply with the provi- for nonshielded conductors or 12 times the overall diameter signs of 310.7. Underground cables shall be installed in for shielded or lead-covered conductors during or after in- accordance with 300.50(A)(1) or (A)(2), and the installa- stallation. For multiconductor or multiplexed single- tion shall meet the depth requirements of Table 300.50. conductor cables having individually shielded conductors. the minimum bending radius is 12 times the diameter of the (1) Shielded Cables and Nonshielded Cables in Metal- individually shielded conductors or 7 times the overall di- Sheathed Cable Assemblies. Underground cables, includ- ameter, whichever is greater. ing nonshielded, Type MC and moisture-impervious metal sheath cables,shall have those sheaths grounded through an 300.35 Protection Against Induction Heating. Metallic effective grounding path meeting the requirements of raceways and associated conductors shall be arranged so as 250.4(A)(5) or (13)(4). They shall be direct buried or in- to avoid heating of the raceway in accordance with the stalled in raceways identified for the use, applicable provisions of 300.20. (2) Other Nonshielded Cables. Other nonshielded cables not covered in 300.50(A)(1)shall be installed in rigid metal 300,37 Aboveground Wiring Methods. Aboveground conduit, intermediate metal conduit, or rigid nonmetallic conductors shall be installed in rigid metal conduit, in in- conduit encased in not less than 75 mm (3 in.) of concrete. termediate metal conduit, in electrical metallic tubing, in rigid nonmetallic conduit, in cable trays, as busways, as (B) Protection from Damage. Conductors emerging from cablebus, in other identified raceways, or as exposed runs the ground shall be enclosed in listed raceways. Raceways of metal-clad cable suitable for the use and purpose. In installed on poles shall be of rigid metal conduit, interme- locations accessible to qualified persons only, exposed runs diate metal conduit, Schedule 80 PVC conduit, or equiva- of Type MV cables,bare conductors, and bare busbars shall lent, extending from the minimum cover depth specified in also be permitted. Busbars shall be permitted to be either Table 300.50 to a point 2.5 m (8 ft) above finished grade. copper or aluminum. Conductors entering a building shall be protected by an 70-136 NATIONAL,ELECTRICAL CODE 2008 Edition ARTICLE 300---WIRING METHODS 300.50 Table 300.50 Minimum Cover' Requirements General Conditions (not otherwise specified) Special Conditions (use if applicable) (4) Raceways Under (5) Buildings or Cables in (6) Exterior Airport Areas Subject to (3) Concrete Runways or Vehicular Traffic, (2) Rigid Metal Slabs, 100 nnnt Adjacent Such as (1) Rigid Conduit and (4 in.) Areas Where Thoroughfares Direct-Buried Nonmetallic Intermediate Minimum Trespass Ls and Commercial Cables`' Conduit' Metal Conduit Thickness' Prohibited Parking Areas Circuit Voltage mm in. mm in. mm in. mm in. mm in. mm in. Over 600 V through 22 kV 750 30 450 18 150 6 100 4 450 18 600 24 Over 22 kV through 40 kV 400 36 600 24 150 6 100 4 450 18 600 24 Over 40 kV 1000 42 750 30 150 6 100 4 450 is 600 24 General Notes: 1. Lesser depths shall be permitted where cables and conductors rise for terminations or splices or where access is otherwise required. 2.Where solid rock prevents compliance with the cover depths specified in this table,the wiring shall be installed in a metal or nonmetallic raceway permitted for direct burial.The raceways shall be covered by a minimum of 50 mm(2 in.)of concrete extending down to rock. 3. In industrial establishments, whete conditions of maintenance and supervision ensure that qualified persons will service the installation, the minimum cover requirements,for other than rigid metal conduit and intermediate metal conduit,shall be permitted to be reduced 150 mm(6 in.) for each 50 mm(2 in.)of concrete or equivalent placed entirely within the trench over the underground installation. Specific Footnotes: 'Cover is defined as the shortest distance in millimeters(inches)measured between a point on the top surface of any direct-buried conductor,cable, conduit,or other raceway and the top surface of finished grade, concrete, or similar cover. ' Listed by a qualified testing agency as suitable for direct burial without encasement.All other nonmetallic systems shall require 50 mm(2 in.) of concrete or equivalent above conduit in addition to the table depth. 'the slab shall extend a minimum of 150 mrn(6 in.)beyond the underground installation,and a warning ribbon or other effective means suitable for the conditions shall be placed above the underground installation. Underaround direct-buried cables that are not encased or protected by Concrete and are buried 750 mm(30 in.)or more below grade shall have their location identified by a warning ribbon that is placed in the trench at least 300 mm(12 in.)above the cables. approved enclosure or raceway from the minimum cover rupted and overlapped, each shield section shall be depth to the point of entrance. Where direct-buried conduc- grounded at one point. tors,raceways, or cables are subject to movement by settle- (D) Backfill. Backfiil containing large rocks, paving mate- ment or frost, they shall be installed to prevent damage to rials, cinders, large or sharply angular substances, or corro- the enclosed conductors or to the equipment connected to sive materials shall not be placed in an excavation where the raceways. Metallic enclosures shall be grounded. materials can damage or contribute to the corrosion of race- (C) Splices. Direct burial cables shall be permitted to be ways, cables, or other substructures or where it may pre- spliced or tapped without the use of splice boxes, provided vent adequate compaction of fill. they are installed using materials suitable for the applica- Protection in the form of granular or selected material tion. The taps and splices shall be watertight and protected or suitable sleeves shall be provided to prevent physical from mechanical damage. Where cables are shielded, the damage to the raceway or cable. shielding shall be continuous across the splice or tap. {E} Raceway Seal. Where a raceway enters from an un- Exception: At splices of an engineered cabling system, me- derground system, the end within the building shall be tallic shields of direct-buried single-conductor cables with sealed with an identified compound so as to prevent the maintained spacing between phases shall be permitted to entrance of moisture or gases, or it shall be so arranged to be interrupted and overlapped. Where shields are inter- prevent moisture from contacting live parts. 2008 Edition NATIONAL ELECTRICAL CODE 70-137 310.1 ARTICLE 310—CONDUCTORS FOR GENERAL WIRING Exception No. 2: Under engineering supervision. ARTICLE 310 grounded neutral conductors in sizes 2 AWG and larger Conductors for General Wiring shall be permitted to be run in parallel for existing installations. FPM to Exception No. 2: Exception No. 2 can be used to 310.1 Scope. This article covers general requirements for alleviate overheating of neutral conductors in existing installa- conductors and their type designations, insulations, mark- tions due to high content or triplen harmonic currents. ings, mechanical strengths, ampacity ratings, and uses. These requirements do not apply to conductors that form an (B) Conductor Characteristics. The paralleled conduc- integral part of equipment, such as motors, motor control- tors in each phase, polarity, neutral, grounded circuit con- lers, and similar equipment, or to conductors specifically ductor, or equipment grounding conductor shall comply provided for elsewhere in this Code. with all of the following: FPN: For flexible cords and cables, see Article 400. For (1) Be the same length fixture wires, see Article 402. (2) Have the same conductor material (3) Be the same size in circular mil area 310.2 Conductors. (4) Have the same insulation type (A) Insulated. Conductors shall be insulated. (5) Be terminated in the same manner Exception: Where covered or bare conductors are specifi- (C) Separate Cables or Raceways.Where run in separate call'permitted elsewhere in this Code. cables or raceways,the cables or raceways with conductors FPN: See 250.184 for insulation of neutral conductors of a shall have the same number of conductors and Shall have solidly grounded high-voltage system. the same electrical characteristics. Conductors of one phase, polarity, neutral, grounded circuit conductor, or (B) Conductor Material. Conductors in this article shall equipment groundingg conductor shall not be required to be of aluminum, copper-clad aluminum, or copper unless have the same physical characteristics as those of another otherwise specified. phase, polarity, neutral, grounded circuit conductor, or 310.3 Stranded Conductors.Where installed in raceways, equipment grounding conductor to achieve balance. conductors of size 8 AWG and larger shall be stranded. (D) Ampaeity Adjustment. Conductors installed in paral- Erc•eption: As permitted or required elsewhere in this lel shall comply with the provisions of 310.15(13)(2)(a). Code. (E) Equipment Grounding Conductors. Where parallel equipment grounding conductors are used, they shall be 310.4 Conductors in Parallel. sized in accordance with 250.122. Sectioned equipment (A) General.Aluminum.copper-clad aluminum,or copper grounding conductors smaller than I/O AWG shall be per- conductors of size 1/0 AWG and larger, comprising each mitted in multieonduetor cables in accordance with 310.13, phase, polarity, neutral, or grounded circuit conductor shall provided the combined circular mil area in each cable corn- be permitted to be connected in parallel (electrically joined plies with 250.122. at both ends). • Exception No. 1: Conductors in sizes smaller than 1/0 310.5 Minimum Size of Conductors. The minimum size of conductors shall be as shown in Table 310.5, except as AWG steal! be permitted to be run in parallel to .strppl' control power to indicating instruments, contactors, relay's, permitted elsewhere in this Code. solenoids, and similar control devices, or for frequencies of Table 310.5 Minimum Size of Conductors 360 HW and higher, provided all of the following apply: (a) They' are contained within the same racelvcn_' or Minimum Conductor Size (AWG) cable. Conductor (h) The cnnpacity' of each individual conductor is sttf= Voltage Rating Aluminum or Copper-Clad fic•ient to carry the entire load current shared by the paral- (Volts) Copper Aluminum lel conduc'tor's. 0-2000 14 12 (c•) The overcurrent protection is such that the ampac•- 2001-8000 8 8 ity of each individual conductor will not be erceeded if one 8001-15,000 2 2 or more of the parallel conductors become inadvertently' 15,001--28,000 1 1 disconnected. 28,001--35,000 110 110 70-138 NATIONAL ELECTRICAL CODE 2(H)8 Edition ARTICLE 310—CONDUCTORS FOR GENERAL WIRING 310.11 310.6 Shielding. Solid dielectric insulated conductors op- (C) Wet Locations. Insulated conductors and cables used erated above 2000 volts in permanent installations shall in wet locations shall comply with one of the following: have ozone-resistant insulation and shall be shielded. All (1) Be moisture-impervious metal-sheathed metallic insulation shields shall be connected to a ground- (2) Be types MTW, RHW, RHW-2, TW, THW, THW-2, ing electrode conductor, grounding busbar, or a grounding THHW, THWN, THWN-2, XHHW, XHHW-2, ZW electrode. Shielding shall be for the purpose of confining (3) Be of a type listed For use in wet locations the voltage stresses to the insulation. Exception No. 1: Nonshielded insulated conductors listed (D) Locations Exposed to Direct Sunlight.Insulated con- bv a qualified testing laboratory shall be permitted for use ductors or cables used where exposed to direct rays of the sun shall comply with ( up to 2400 volts under the following conditions: D)(1) or(D)(2): {a} Conductors shall have insulation resistant to elec- (1) Conductors and cables Shall be listed, or listed and tric discharge and surface tracking, or the insulated con- ductor(s) shall be covered with a material resistant to (2) Conductors and cables shall be covered with insulating ozone, electric discharge, and surface tracking. material, such as tape or sleeving, that is listed, or (b) Where used in wet locations, the insulated conduc- listed and marked, as being sunlight resistant tor(s)shall have an overall nonmetallic jacket or a c•ontinu- 310.9 Corrosive Conditions. Conductors exposed to oils, ous metallic sheath. greases, vapors, gases, fumes, liquids, or other substances (c•) Insulation and jacket thicknesses shall be in accor- having a deleterious effect on the conductor or insulation dance with Table 310.13(D). shall be of a type suitable for the application. Exception No. 2: Where permitted in 310.7,Exception No.2. 310.10 Temperature Limitation of Conductors. No con- 310.7 Direct-Burial Conductors. Conductors used for ductor shall be used in such a manner that its operating direct-burial applications shall be of a type identified for temperature exceeds that designated for the type of insu- such use. lated conductor involved, In no case shall conductors be Cables rated above 2000 volts shall be shielded. associated together in such a way, with respect to type of circuit,the wiring method employed, or the number of con- Exception No. 1: Nonshielded multiconductor cables rated ductors, that the limiting temperature of any conductor is 2001-2400 volts shall be permitted if the cable has an exceeded. overall metallic sheath or armor. FPN: The temperature rating of a conductor [see Table The metallic shield, sheath,or armor shall be connected 310.13(A)and Table 310.13(0)] is the maximum tempera- ture,at any location along its length, that the conductor can YO a grounding electrode Conductor, grounding bulbar, or a withstand over a prolonged time period without serious grounding electrode. degradation. The allowable ampacity tables, the ampacity Exception No. 2: Airfield lighting cable used in series cir- tables of Article 310 and the ampacity tables of Annex B, the correction factors at the bottom of these tables,and the cults that are rated up to 5000 volts and are powered by notes to the tables provide guidance for coordinating con- regulators shall be permitted to be nonshielded. ductor sizes,types,allowable ampacities,ampacities,ambi- FJ'N to Exception No. 2• Federal Aviation Administration ent temperatures, and number of associated conductors. (FAA)Advisory Circulars (ACs) provide Additional practices The principal determinants of operating temperature and methods for airport lighting. are as follows: (1) Ambient temperature—ambient temperature may vary FPN No. 1: See 300.5 for installation requirements for along the conductor length as well as from time to conductors rated 500 volts or less. time. FPN No. 2: See 300.50 for installation requirements for (2) Heat generated internally in the conductor as the result conductors rated over 600 volts. of load current flow, including fundamental and har- monic currents. (3) The rate at which generated heat dissipates into the 310.8 Locations. ambient medium.Thermal insulation that covers or sur- rounds conductors affects the rate of heat dissipation. (A) Dry Locations. Insulated conductors and cables used in (4) Adjacent load-carrying conductors--adjacent conduc- dry locations shall be any of the types identified in this Code, tors have the dual erect of raising the ambient tempera- ture and impeding heat dissipation. (B) Dry and Damp Locations. Insulated conductors and 310.11 Marking. cables used in dry and damp locations shall be Types FEP, FEPB, MTW, PFA, RHH, RHW, RHW-2, SA, THHN, (A) Required Information. All conductors and cables THW, THW-2, THHW, THWN, THWN-2, TW, XHH, shall be marked to indicate the following information, us- XHHW, XHHW-2, Z, or ZW. ing the applicable method described in 310.1I(B): 2008 Edition NATIONAL ELECTRICAL CODE 70-139 310.12 ARTICLE 310 CONDUCTORS FOR GENERAL WIRING (1) The maximum rated voltage. (2) Switchboard wires (2) The proper type letter or letters for the type of wire or (3) Metal-covered, single-conductor cables cable as specified elsewhere in this Code. (4) Type AC cable (3) The manufacturer's name, trademark, or other distinc- tive marking by which the organization responsible for (4) Optional Marking of Wire Size. The information re- the product can be readily identified. quired in 310.11(A)(4) shall be permitted to be marked on (4) The AWG size or circular mil area. the surface of the individual insulated conductors for the following multiconductor cables: FPN: See Conductor Properties, Table 8 of Chapter 9, for (1) Type MC cable conductor area expressed in Si units for conductor sizes (2) Tray cable specified in AWG or circular mil area. y (5) Cable assemblies where the neutral conductor is (3) Irrigation cable smaller than the ungrounded conductors shall be so (4) Power-limited tray cable marked. (5) Power-limited fire alarm cable (B) Method of Marking. (6) Instrumentation tray cable (1) Surface Marking. The following conductors and (C) Suffixes to Designate Number of Conductors.A type cables shall be durably marked on the surface. The AWG letter or letters used alone shall indicate a single insulated size or circular mil area shall be repeated at intervals not conductor. The letter suffixes shall be indicated as follows: exceeding 610 mm (24 in.). All other markings shall be (1) D — For two insulated conductors laid parallel within repeated at intervals not exceeding 1.0 m (40 in.). an outer nonmetallic covering (1) Single-conductor and multiconductor rubber- and (2) M -- For an assembly of two or more insulated con- thermoplastic-insulated wire and cable ductors twisted spirally within an outer nonmetallic (2) Nonmetallic-sheathed cable covering (3) Service-entrance cable (D) Optional Markings. All conductors and cables con- (4) Underground feeder and branch-circuit cable tained in Chapter 3 shall be permitted to be surface marked (5) Tray cable to indicate special characteristics of the cable materials. (6) Irrigation cable These markings include, but are not limited to, markings (7) Power-limited tray cable for limited smoke, sunlight resistant, and so forth. (8) Instrumentation tray cable 310.12 Conductor Identification, (2) Marker Tape. Metal-covered multiconductor cables shall employ a marker tape located within the cable and (A) Grounded Conductors. Insulated or covered grounded running for its complete length. conductors shall be identified in accordance with 200.6. Exception No. l: Mineral-insulated, metal-sheathed cable. (B) Equipment Grounding Conductors. Equipment Exception No. 2: Tire AC cable. grounding conductors shall be in accordance with 250.119. Exception No. 3: The information required in 310.11(A) (C) Ungrounded Conductors. Conductors that are in- shall he permitted to he durable marked on the outer non- tended for use as ungrounded conductors,whether used as a metallic covering of Type MC, Type ITC, or Tire PLTC cables at intervals not exceeding 1.0 m (40 in.). single conductor or in multiconductor cables, shall be fin- ished to be clearly distinguishable from grounded and Exception No. 4: The information required in 310.11(A) grounding conductors. Distinguishing markings shall not shall he penuitted to be durably marked on a nonmetallic conflict in any manner with the surface markings required covering tinder the metallic sheath of Tyne ITC or Type by 310.11(B)(1). Branch-circuit ungrounded conductors PLTC cable at intervals not exceeding 1.0 in (40 in.). shall be identified in accordance with 210.5(C). Feeders FPN: Included in the group of metal-covered cables are shall be identified in accordance with 215.12. Type AC cable(Article 320),Type MC cable(Article 330), Exception: Conductor identification shall be permitted in and lead-sheathed cable. accordance with 200.7. (3) Tag Marking. The following conductors and cables shall be marked by means of a printed tag attached to the 310.13 Conductor Constructions and Applications. In- coil, reel, or carton: sulated conductors shall comply with the applicable provi- (1) Mineral-insulated, metal-sheathed cable sions of Table 310.13(A) through Table 310.13(E). 70-140 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 310-CONDUCTORS FOR GENIERAL WIRING 310.13 These conductors shall be permitted for use in any of to pressure, such as at points of support. Thermoplastic the wiring methods recognized in Chapter 3 and as speci- insulation, where used on do circuits in wet locations, may fied in their respective tables or as permitted elsewhere in result in electroendosmosis between conductor and insulation. this Code. FM Thermoplastic insulation may stiffen at temperatures Equipment grounding conductors Shall be permitted to lower than -1(1°C (f14°F). Thermoplastic insulation may be sectioned within a Misted multiconduetor Cable,provided also be deformed at normal temperatures where subjected the combined circular mil area complies with 250.122. Table 310.13(A) Conductor Applications and Insulations Rated 600 Volts Thickness or Insulation Maximum Operating Trade Name Tvpe better Temperature Application Provisions Insulation AWG or kcmil mm mils Outer Covering' Fluorinated FEP or 90°C Dry and damp locations Fluorinated ethylene 14-10 0.51 20 None ethylene FEPB 194°F propylene 8-2 0.76 30 propylene 2011°C Dry locations-special Fluorinated ethylene 14-8 0.36 14 Glass braid 392°F applications' propylene 6-2 0.36 14 Glass or other suitable braid material Mineral insulation Ml 90°C Dry and wet locations Magnesium oxide 18-16' 0.58 23 Copper or alloy steel (metal sheathed) 194°F 16-10 0.91 36 250°C For special applications= 9-4 1.27 50 482°F 3-500 1.40 55 Moisture-,heat-. MTW 60°C Machine tool wiring in Flame-retardant (A) (A) (A)None and oil-resistant 140°F wet locations moisture-,heat-,and (B)Nylon Jacket or thermoplastic oil-resistant equrvalem 90°C Machine tool wiring in thermoplastic 22-12 0,76 30 19.1°F dry locations. 10 0.76 30 FPN:See NFPA 79. 8 1.14 45 6 1.52 60 4-2 1.52 61) 1-4/0 2.03 80 213-500 2.41 95 501-1000 2.79 110 Paper 85°C For underground service Paper Lead sheath 185°F conductors,or by .pecial permission Perfluoro-alkoxy PFA 90°C Dry and damp locations Perfluorn•alkoxy 14--I0 0.51 20 None 194°F 8-2 0.76 30 2W°C Dry locations-special 1-4/0 1.14 45 392°F applications2 Perfluoru-alkoxy PFAH 250°C Dry locations only.Only Perfluoro-alkoxy 14-10 0.5t 20 None 492-F for leads within apparatus 8-2 0.76 30 or within raceways 1-410 1.14 45 connected to apparatus (nickel or nickel-coated copper only) Thermo+et RHH 90°C Dry and damp locations 1410 1.14 45 Moisture-resistant, • [94°F 8-2 1.52 60 flame-retardant. 1-4A) 2.03 80 nonmetallic covering' 213-500 2.4[ 95 501-I(KXI 2.79 110 1001-21x)0 3.18 125 Moisture- RHW° 75°C try and wet locations Flame-retardant, 14-10 1.14 45 Moisture-resistant, resistant 167°F moisture- 8-2 1.52 60 flame-retardant, thermoset resistant thermoset 1-4/0 2.03 80 nonmetallic caverirtga 213-5[X) 2.41 95 RKW-2 94°C 501-1000 2.79 H0 1944F M01-2000 3,18 12.5 Silicone SA 90°C Dry and damp laadons Silicone rubber 14-10 1.14 45 Glassy or other suitable 194°F 8-2 1.52 60 braid material 1-11() 2.03 8() 21X)°C For special application' 213-500 2.41 95 392°F 5()1-[000 2.79 110 1001-2000 3.18 125 (Continues) 2008 Edition NATIONAL ELECTRICAL CODE 70-141 310.13 ARTICLE 310-CONDUCTORS FOR GENERAL WIRING Table 310.13(A) Continued Thickness of Insulation Maximum Operating Trade Name Tape Letter "Temperature Application Provisions Insulation A%VG or kcmil ntnt mils Outer Covering' Thermoset SIS 911°C Switchboard wiring only Flame-retardant 14-10 0.76 30 None 194"F thermoset 8-2 1.14 45 1-410 241 55 Thermoplastic and THS 91T{' Switchboard wiling only Thermoplastic I4-10 0.76 30 Flame retardant. fibrous outer 194'F 8 1.14 45 nonmetallic covering bran[ 6-2 1.52 6) 1-410 2,03 SQ Extended polyieira- TFE 250-C Dry locations only.Only Extruded po[yieira- 14-1(1 0.51 20 None lluuro- 482"F for leads within Iluunoethylene 8-2 0.76 30 ethylene apparatus or within 1-4111 1.14 45 raceways connected to apparatus,or as open wiring(nickel or nickel-coated copper only I Heat-resistant THHN WIC Dry and damp kwations Flame-retardant, 14-12 0,39 15 NN[on jacket ur thermoplastic 194'F heat-resistant 10 0.51 20 equivalent thermoplastic 8fi O-76 aft 4-2 L02 Ail [-41[1 1.27 50 250-5M 1.52 60 501-1000 1.78 70 Moisture and THHW 75'C Wet Iocatiom Flame-retardant, 14-10 0.76 311 Nome heat-resistant 167'F moisture-and 8 1.14 45 thernroPlastic heat-resis(ant 6-2 1.52 611 9011 Dry location thermoplastic 1-410 2.03 80 194'F 213-5(N) 2.41 95 501-14MMI 2.79 110 I W 1-2000 1,113 125 Monmre-and TIM 75°C Dry and wet locatums Flame-retartlam. 14-10 0.76 30 None heat-resistant 167"F moisture-and 8 1.14 45 thermoplastic M)"C Special applications heat-resistant (r2 1.52 6) 194"F within electric discharge themwplastic 1-111 2.03 80 lighting equipment. 213-5(M) 2.41 95 Limited to HMXI 501-1(MHI 2.79 IM open-circuit volts or 1001-20W 3,16 125 lc%%.('ate [4-8 only as Permitted in 410.68) THW2 WC Dry and wet WAIinns I9 F Moisture-and THWN 75-C Dry and wet locations Hame.retnrd.mt, 14-12 0.38 l5 Nylon jacket or heat-resistant 167-F moisture-and 10 0.51 20 equivalent thermoplastic heat-resistant R-6 0.76 10 thermoplastic 4-2 1.02 40 THWN•2 90°C 1-410 127 50 194"F 25S>-5(11) 1,52 60 5tH-1(0[1 1.78 70 Moisture- TW N)C Dry and wet locations Flame-retardant, 14-10 0.76 3() None resistant 140'F moisture- 8 1.14 45 thermoplastic resistant 6-2 1.52 60 thermoplastic 1-410 2.03 91) 213-5(H) 2.41 95 501-I(XXI 2.79 110 1(X)1-2(MM) 3.18 125 Underground feeder OF 60-C See Article 340. Moisture- 14-111 L52 60S Integral with insulation and branch-circuit 140^F resistant 8 2 103 0 cable-single 1-410 2-41 95, conductor(fur Type OF cable 75"C Moisture-and employing more 167*F- heat-resistant than one conducuu.see Article 340.) 70-142 NATIONAL ELECTRICAL CODF 2008 Edition ARTICLE 310-CONDUCTORS FOR GENERAL MR]NG 310.13 Table 310.13(A) Continued Thickness of Insulation Maximum Operating Trade Name Type Leiter Temperature Application Provisions Insulation AIVG or kemil mm mils Outer Covering' Underground USE 75°C See Article 338. Heat-and 14-10 1.14 45 Moisture-resistant service- 167°F moisture-resistant 8-2 1.52 611 nonmetallic covering entrance cable- 1-4/0 2,03 841 (See 338.2.1 single conductor 213-500 2.41 05; (For Type USE 501-I(K10 2.79 1111 cable employing 11101-2(KK) 3.18 125 more than one conductor,see Article 338.1 USE-2 9(rc Dry and wet locations 194'F Thermoset XHH 90°C Dry and damp locations Flame-retardant 14-10 0,76 30 None 194°F thermoset 8-2 1.14 45 1-4/0 1.40 55 213-5(K) 1.65 65 501-1(1(1(1 2.03 80 I(Kll-2000 2.41 95 Moisture- XHHW' 901C Dry and damp locations Flame-retardant, 1.1-10 0.76 30 None resistant 194°F moisture- 8-2 1.14 45 thermoset 75°C Wet locations resistant thermoset 1-410 1.40 55 167°F 213-500 1.65 65 SOI-I(KK1 ?03 80 I(K11-2(KK) 2.41 95 Moisture- XHHW-2 90°C Dry and wet locations Flame-retardant, 14-10 0.76 30 None resistant 194°F moisture. 8-2 1.14 45 thermowl resistant thermoset 1-410 1.40 55 213-50(1 1.65 65 501-11KK] 2.03 80 1001-20(10 2.41 95 Modified ethylene Z 90°C Dry and damp locations Modified ethylene 14-12 0.38 15 None tetrafluoro- 194°F tetralfuom- 10 0.51 20 ethylene 150°C Dry locations-special ethylene 8-4 n.64 25 302°F applications' 3-I 0.69 35 110-41n 1.14 1 45 Modified ethylene ZW 75°C Wet location,. Modified ethylene 14•-10 0,76 30 None tetraftuoro- 167°F tetrafluoro- 8-2 1.14 45 ethylene 9(1°C Dry and damp locations ethylene 194°F 150°C Dry locations-special 302°F applklflions2 ZW-2 9VC Dry and Wet 100ati0ns 194°F t Some insulations do not require an outer covering. `Where design conditions require maximum conductor operating temperatures above 90°C (194°F). For signaling circuits permitting 300-volt insulation. a Some rubber insulations do not require an outer covering. s Includes integral jacket. For ampacity limitation,see 340.80. insulation thickness shall be permitted to be 2.03 mm(80 mils) for listed Type USE conductors that have been subjected to special investigations.The nonmetallic covering over individual rubber-covered conduc- tors of aluminum-sheathed cable and of lead-sheathed or multiconductor cable shall not be required to be flame retardant. For Type MC cable,see 330.104.For nonmetallic-sheathed cable,see Article 334, Part 111. For Type OF cable, see Article 340, Pan III. 2008 Edition NATIONAL ELECTRICAL CODE 70-143 310.13 ARTICLE 310-CONDUCTORS FOR GENERAL WIRING Table 310.13(B) Thickness of Insulation for Nonshielded 'I'vpes RHH and RHW Solid Dielectric Insulated Conductors Rated 2000 Volts Column A' Column B2 Conductor Size (AWG or kcmil) mm mils mm mils 14-10 2.03 80 1.52 60 8 2.03 80 1.78 70 6-2 2.41 95 1.78 70 1-2/0 2.79 110 2.29 90 3/(1-1/0 2.79 Il0 2.29 90 213-500 3.18 125 2.67 105 501-1000 3.56 140 3.05 120 1001-2000 3.56 140 3.56 140 `Column A insulations are limited to natural.SBR,and butyl rubbers. 'Colman B insulations are materials such as cross-linked polyethyl- ene,ethylene propylene rubber, and composites thereof. Table 310.13(C) Conductor Application and Insulation Rated 2001 Volts and Higher Trade Maximum Operating Application Name Type Letter Temperature Provision Insulation Outer Covering Medium voltage solid MV-90 90°C 105°C Dry or wet locations Thermo- Jacket, sheath, or dielectric MV-105* plastic or thermo- armor setting "Where design conditions require maximum conductor temperatures above 90'C. Table 310.13(I)) Thickness of Insulation and Jacket for Nonshielded Solid Dielectric insulated Conductors Rated 2400 Volts Dry Locations, Single Conductor Wet or Dry Locations Without With Jacket Single Conductor Jacket Multiconductor Insulation Insulation Jacket Insulation Jacket Insulation* Conductor Size (AWG or kcmil) mm mils mm mils mm mils mm mils mm mils mm mils 8 2.79 110 2.29 90 0.76 30 3.18 125 2.03 80 2.29 90 6 2.79 ll0 2.29 90 0.76 30 3.18 125 2.03 80 2.29 90 4-2 2.79 110 2.29 90 1.14 45 3.18 125 2.03 80 2.29 90 1-2/0 2.79 110 2.29 90 1.14 45 3.18 125 2.03 80 2.29 90 3A"A) 2.79 110 2.29 90 1.65 65 3.18 125 2.41 95 2.29 90 213-500 3,05 120 2.29 90 1.65 65 3.56 140 2.79 110 2.29 90 501-750 3.30 130 2.29 90 1,65 65 3.94 155 3.18 125 2.29 90 75 1-1000 3.30 130 2.29 90 1.65 65 3.94 155 3.18 125 2.29 90 1001--1250 3.56 140 2.92 115 1.65 65 4.32 170 3.56 140 2.92 115 1251-1500 3.56 140 2.92 115 2.03 80 4.32 170 3.56 140 2.92 115 1501-2000 3.56 140 2.92 115 2.03 80 4.32 170 3.94 155 3.56 140 *Under a common overall covering such as a jacket, sheath, or armor. 70-144 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 310-CONDUCTORS FOR GENERAL WIRING 310,15 Table 310.13(E) Thickness of Insulation for Shielded Solid Dielectric Insulated Conductors Rated 2001 to 35,000 Volts 2001-5000 Volts 5001-8000 Volts 8001-15,000 Volts I5,001-25,000 Volts 100 100 133 173 100 133 173 100 133 173 Percent Percent Percent Percent Percent Percent Percent Percent Percent Percent Conductor Insulation Insulation Insulation Insulation Insulation Insulation Insulation Insulation Insulation Insulation Size Level ' Level ' Level 2 Level' Level' Levelx Level; Level' Level' Level.' (AM. or kcmil) mm mils mm mils mm mils mm mils mm mils mm mils mm mils mm mils mm mils mm mils 8 2.29 90 - - - - - - - - - - - - - - - - - 6-4 2.29 90 2.92 115 3.56 140 4.45 175 - - - 2 2.29 90 2.92 115 3.56 140 4.45 175 4.35 175 5.59 220 6.60 260 - - - - - - 1 2.29 941 2.92 115 3,56 140 4.45 175 4.45 175 5.59 220 6.60 260 6.60 260 8.13 320 10.67 420 1/0-2WO 2.29 90 2.92 115 3.56 140 4.35 175 3.45 175 5.59 220 6.60 260 6.60 260 8,13 320 10.67 420 25,001-28,000 volts 28,001-35,000 volts 100 133 173 100 133 173 Percent Percent Percent Percent Percent Percent Conductor Insulation Insulation Insulation Insulation Insulation Insulation Size Level' Level Level' Level' Level2 Level' (AWC. or kcmil) mm mils mm mils mm mils mm mils mm mils mm mils l 7.11 280 8.76 345 11,.30 445 - - - - - 1/4F-2(H)l 7.11 280 8.76 345 11.30 445 8.76 345 10.67 420 14.73 580 100 Percent Insulation Level,Cables in this category Shall be permitted to be applied where the system is provided with relay protection such that ground faults will be cleared as rapidly as possible but, in any case,within 1 minute.While these cables are applicable to the great majority of cable installations that are on grounded systems,they shall be permitted to be used also on other systems for which the application of cables is acceptable, provided the above clearing requirements are met in comple(ely de-energizing the faulted section. 2133 Percent Insulation Level.This insulation level corresponds to that formerly designated for ungrounded systems.Cables in this category shall be permitted to be applied in situations where the clearing time requirements of the 100 percent level category cannot be met and yet there is adequate assurance (hat the faulted section will be de-energized in a time not exceeding I hour. Also, they shall be permitted to be used in 100 percent insulation level applications where additional insulation is desirable. '173 Percent Insulation Level. Cables in this category shall be permitted to be applied under all of the following conditions: (l) In industrial establishments where the conditions of maintenance and supervision ensure that only qualified persons service the installation (2)Where the fault clearing time requirements of the 133 percent level category cannot be met (3)Where an orderly shutdown is essential to protect equipment and personnel (4)There is adequate assurance that the faulted section will be de-energized in an orderly shutdown Also, cables with this insulation thickness shall be permitted to be used in 100 or 133 percent insulation level applications where additional insulation strength is desirable. 310.14 Aluminum Conductor Material. Solid aluminum No. 4, for branch circuits and 215.2(A), FPN No. 2, for conductors 8, 10, and 12 AWG shall be made of an AA- feeders. 8000 series electrical grade aluminum alloy conductor ma- FPN No. 2: For the allowable ampacities of Type MTW terial, Stranded aluminum conductors 8 AWG through 1000 wire, see Table 13.5.1 in NFPA 79-2007, Electrical Stan- kemil marked as Type RHH, RHW,XHHW,THW,THHW, Bard for htdustrial Mac•hinery THWN, THHN, service-entrance Type SE Style U and SE (2) Selection of Ampacity. Where more than one calcu- Style R shall be made of an AA-8000 series electrical grade lated or tabulated Ampacity could apply for a given circuit aluminum alloy conductor material. length, the lowest value shall he used. 310.15 Ampacities for Conductors Rated 0-2000 Volts. Exception: Where two different ampacities apply to adja- cent portions of a circuit, the higher atnpac•ity shall be (A) General. permitted to be used beyond the point of transition, a dis- tance equal to .3.0 in (]Oft) or 10 percent of the circuit {]) Tables or Engineering Supervision. Ampacities for length figured at the higher anrpacit}, whichever is less. conductors shall be permitted to be determined by tables as provided in 310.15(8) or under engineering supervision, as FPN: See 110.14(C) for conductor temperature limitations provided in 310.15(0). due to termination provisions. FPN No. l: Ampacities provided by this section do not (B) Tables. Ampacities for conductors rated 0 to 2000 take voltage drop into consideration. See 210.19(A). FPN volts shall be as specified in the Allowable Ampacity Table 2008 Edition NATIONAL ELECTRICAL CODE 70-145 310.15 ARTICLE 310—CONDUCTORS FOR GENERAL WIRING 310.16 through Table 310.19, and Ampacity Table 310.20 FPN No. 2: See 366.23(A) for adjustment factors for con- and Table 310.21 as modified by (13)(1) through (B)(6). ductors in sheet metal auxiliary gutters and 376.22(B) for FPN: Table 310.16 through Table 310.19 are application adjustment factors for conductors in metal wireways. tables for use in determining conductor sizes on loads calcu- Exception No. 1: Where conductors of different systems, as lated in accordance with Article 220. Allowable ampacities provided in 300.3, are installed in a common raceway or result from consideration of one or more of the following: cable, the derating factors shown in Table 310.15(B)(2)(a) (1) Temperature compatibility with connected equipment, shall apply only to the number of power and lighting con- especially the connection points. (2) Coordination with circuit and system overcurrent pro- ductors (Articles 210, 215, 220, and 230). tection. Exception No. 2: For conductors installed in cable trays, (3) Compliance with the requirements of product listings the provisions of 392.11 shall apply. or certifications. See 110.3(B). (4) Preservation of the safety benefits of established indus- Exception No. 3: Derating factors shall not apply to conduc- try practices and standardized procedures. tors in nipples having a length not exceeding 600 mm(24 in.). (1) General. For explanation of type Ietters used in tables Exception No. 4: Derating factors shall not apply to un- and for recognized sizes of conductors for the various con- derground conductors entering or leaving an outdoor ductor insulations, see Table 310.13(A) and Table trench if those conductors have physical protection in the 310.13(B). For installation requirements, see 310.1 through form of rigid metal conduit, intermediate metal conduit, or 3 10.10 and the various articles of this Code. For flexible rigid nonmetallic conduit having a length not exceeding cords,see Table 400.4,Table 400.5(A),and Table 400.5(B). 3.05 m (10 ft) and if the number of conductors does not (2) Adjustment Factors. exceed four. (a) More Than Three Current-Carrying Conductors in Exception No. 5: Adjustment factors shall not apply to a Raceway or Cable. Where the number of current-carrying Type AC cable or to Type MC cable without an overall conductors in a raceway or cable exceeds three, or where outer jacket under the following conditions: single conductors or multiconductor cables are installed (1) Each cable has not more than three current-carrying without maintaining spacing for a continuous length longer conductors. than 600 mm (24 in.) and are not installed in raceways, the (2) The conductors are 12 AWG copper allowable ampaeity of each conductor shall be reduced as (3) Not more than 20 current-carrying conductors are shown in Table 310.15(B)(2)(a). Each current-carrying con- bundled, stacked or supported on "bridle rings." ductor of a paralleled set of conductors shall be counted as a current-carrying conductor. A 60 percent adjustment factor shall be applied where the Table 310.15(B)(2)(a) Adjustment Factors for More Than current-carrying conductors in these cables that are Three Current-Carrying Conductors in a Raceway or Cable stacked or bundled longer than 600 mm (24 in.) without maintaining spacing exceeds 20. Percent of Values in Tables (b) More Than One Conduit, Tube, or Raceway. Spacing Number of 310.16 through 310.19 as between conduits, tubing, or raceways shall be maintained. Current-Carrying Adjusted for Ambient Conductors Temperature if Necessary (c) Conduits Exposed to Sunlight on Rooftops. Where 4-6 80 conductors or cables are installed in conduits exposed to 7_9 70 direct sunlight on or above rooftops,the adjustments shown 10-20 50 in Table 310.15(B)(2)(c) Shall be added to the outdoor tem- 21-30 45 perature t0 determine the applicable ambient temperature 31-40 40 for application of the correction factors in Table 310.16 and 41 and above 35 Table 310.1$. FPN No. 1: See Annex B, Table B.310.11, for adjustment FPN: One source for the average ambient temperatures in factors for more than three current-carrying conductors in a Various locations is the ASHRAE Handbook--Fundamen- raceway or cable with load diversity. tals. 70-146 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 310—CONDUCTORS FOR GENERAL WIRING 310.15 f Table 310.15(B)(2)(c) Ambient Temperature Adjustment for main disconnect and the panelboard that Supplies,either by l Conduits Exposed to Sunlight On or Above Rooftops branch circuits or by feeders,or both, alll loads that are part or associated with the dwelling unit.The feeder conductors Distance Above Roof to Bottom of Temperature Adder to a dwelling unit shall not be required to have an allowable Conduit C of ampacity rating greater than their service-entrance conduc- tors. The grounded conductor shall be permitted to be 0- 13 mm ('/ in.) 33 60 smaller than the ungrounded conductors, provided the re- Above 13 mm f%in.)-90 mm(31/., in.) 22 40 quirements of 215.2, 220.61, and 230.42 are met. Above 90 mm (3Y: in.)--300 mm(12 in.) 17 30 Table 310.15(B)(6) Conductor Types and Sizes for Above 300 min (12 in.)-900 mm 14 25 120/240-Volt,3-Wire, Single-Phase dwelling Services and (36 in.) Feeders. Conductor Types RHH, RHW, RHW-2,THHN, THHW,THW,THW-2, THWN,THWN-2, XHHW, F1'N to Table 310.15(13)(2)(c):}(2}(G): The temperature adders in XHHW-2, SE, USE, USE-2 Table 310.15(B)(2)(c)are based on the results of averaging the ambient temperatures. Conductor(AWG or kemil) (3) Bare or Covered Conductors. Where bare or covered Aluminum or conductors are installed with insulated conductors,the tem- Service or Feeder Copper-Clad perature rating of the bare or coveted conductor shall be Rating (Amperes) Copper Aluminum equal to the lowest temperature rating of the insulated con- 100 4 2 ductors for the purpose of determining ampacity. 110 3 1 (4) Neutral Conductor. 125 2 110 150 I 2/{) (a) A neutral conductor that carries only the unbal- 175 110 310 anced current from other conductors of the same circuit 200 225 3/310 4/0 0 250 shall not be required to be counted when applying the pro- 250 410 300 visions of 310.15(B)(2)(a). 300 250 350 (b) In a 3-wire circuit consisting of two phase eonduc- 350 350 500 tors and the neutral conductor of a 4-wire, 3-phase, wye- 400 400 600 connected system, a common conductor carries approxi- mately the same current as the line-to-neutral load currents of the other conductors and shall be counted when applying the provisions of 310.15(B)(2)(a). (C) Engineering Supervision. Under engineering supervi- (c) On a 4-wire, 3-phase wye circuit where the major sion, conductor ampacities shall be permitted to be calcu- portion of the load consists of nonlinear loads, harmonic cur- lated by means of the following general formula: rents are present in the neutral conductor: the neutral conduc- tor shall therefore be considered a current-carrying conductor. /_ 'I'C--(7:1—+A 7D) (5) Grounding or Bonding Conductor. A grounding or RDC(1+YC)RCA bonding conductor shall not be counted when applying the provisions of 310.15(B)(2)(a). where: (6) 1201240-Volt, 3-Wire, Single-Phase Dwelling Ser- TC = conductor temperature in degrees Celsius (°C) vices and Feeders. For individual dwelling units of one- TA = ambient temperature in degrees Celsius (°C) family, two-family, and multifamily dwellings, conductors, ATD = dielectric loss temperature rise as listed in Table 310.15(B)(6), shall be permitted as RDC = do resistance of conductor at temperature TC 1201240-volt, 3-wire, single-phase service-entrance con- YC = component ac resistance resulting from skin ductors, service-lateral conductors, and feeder conductors effect and proximity effect that serve as the main power feeder to each dwelling unit RCA = effective thermal resistance between conductor and are installed in raceway or cable with or without an and surrounding ambient equipment grounding conductor. For application of this sec- tion, the main power feeder shall be the feeder between the FPN: See Annex B for examples of formula applications. 2008 Edition NATIONAL ELECTRICAL CODE 70-147 310.15 ARTICLE 310 CONDUCTORS FOR GENERAL WIRING Table 310.16 Allowable Ampacities of Insulated Conductors Rated 0 Through 2000 Volts, 60°C Through 90°C (140°F Through 194 1F), Not More Than Three Current-Carrying Conductors in Raceway, Cable, or Earth (Directly Buried), Based on Ambient Temperature of 30°C (86°F) Temperature Rating of Conductor[See Table 310.13(A).] 60°C 60°C(1.40°F) 75°C(167°F) 90°C(194°F) (140°F) 75°C(167°F) 90°C(19VF) 'I)rpes TBS,SA,SIS, Types TBS,SA, FEP,FEPB,MI,RHH, SIS,THHN, RHW-2,THHN, THHW,THW-2, Types RHW, THHW,THW-2, Types RHW, THWN-2,RHH, THHW,THW, THWN-2,USE-2, THHW,TRW, RHW-2,USE-2, Size ANVG or THWN,XHHW, XHH,XHHW, Types TW, THWN,XHHW, XHH,XHHW, kemil Types TW,OF USE,ZW XHHW-2,ZW-2 OF USE XHHW-2,ZW-2 ALUMINUM OR COPPER-CLAD COPPER ALUMINUM Size AWG or kcmiI 18 - 14 - - - 16 18 - - - 14• 211 20 25 - - - 12* 25 25 30 20 20 25 10' 30 35 40 25 30 35 8 40 50 55 30 40 45 6 55 65 75 40 50 60 4 70 85 95 55 65 75 3 85 100 110 65 75 85 2 95 115 130 75 90 100 1 110 130 150 85 l0 115 1 110 125 150 170 too 120 135 1/0 210 145 175 195 115 135 150 210 310 165 20(1 225 130 175 310 410 195 230 260 150 180 205 410 250 215 255 290 170 205 230 250 300 240 285 320 190 230 255 inn 350 260 310 350 210 250 280 350 400 280 335 380 225 270 305 400 50 320 380 430 260 310 350 500 600 355 420 475 285 340 385 600 700 385 460 520 310 375 420 700 750 400 475 535 320 385 435 750 8(11) 410 490 555 330 395 450 01 9011 435 520 585 355 425 480 900 100(1 455 545 615 375 445 500 100 1250 495 590 665 405 485 545 1250 1500 520 625 705 435 520 585 1500 1750 545 650 735 455 545 615 1750 2(1(X1 560 665 750 470 560 630 2000 CORRECTION FACTORS Ambient Temp. For ambient temperatures other than 30°C(86°F),multiply the allowable ampacities shown above by the appropriate Ambient Temp.(°F) (°C) Factor shown below. 21-25 1.08 1.05 1.04 1,08 1.05 1.04 70-77 26-30 1.0 1.00 1.00 1.00 1.00 1.0 78-86 31-35 0.91 0.94 0.96 0.91 0.94 0.96 87-95 360 0.82 0.88 0.91 0.82 1 0.88 0.91 96-104 4145 0.71 0.82 0.87 0.71 0.82 0.87 105-113 46-50 0.58 0.75 0.82 0.58 0.75 0,82 114-122 51-55 0.41 0.67 0.76 0.41 0.67 0.76 123-131 56-60 - 0.59 0.71 - 0.58 0.71 132-140 61-70 - 0.33 0.58 - 0.33 0.58 141-158 71-80 - - 0.41 - - 0,41 159-176 * See 240.4(D). 70-148 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 310-CONDUCTORS FOR GENERAL WIRING 310.15 Table 310.17 Allowable Ampacities of Single-Insulated Conductors Rated 0 Through 2000 Volts in Free Air, Based on Ambient Air Temperature of 30°C (86°F) Temperature Rating of Conductor[See Table 310.13(A).] 60-C(140°F) 75°C(167°F) 90°C (194°F) 60°C(140°F) 75-C(167°F) 90°C (194°F) Types TBS,SA,SiS, Types TBS,SA,SIS, FEP, FEPB,MI,RHH, THHN,THHW, Types RHW, RHW-2,THHN,THHW, Types RHW, THW-2,THWN-2, THHW,THW, THW-2,THWN-2, THHW,THW, RHH,RHW-2, USE-2, THWN, USE-2,XHH,XHHW, THWN, XHH,XHHW, Types TW,OF XHHW,ZW XHHW-2,ZW-2 Types TW,OF XHHW XHHW-2,ZW-2 Size AWG or Size AWG or kcmil COPPER ALUMINUM OR COPPER-CLAD ALUMINUM kcmil 18 - - 18 16 - 24 14" 25 30 35 - 12* 70 35 40 25 30 35 12* IU* 4O 5(] 55 35 44) 40 11i 8 60 70 80 45 55 Ell 8 6 80 95 105 60 75 80 6 4 105 125 140 80 100 110 4 3 120 145 165 95 115 130 7 2 141) 170 190 110 135 150 2 1 165 195 220 130 155 175 l H0 195 230 260 150 180 21)5 IA) 2/() 225 265 300 175 210 275 210 3A) 260 310 350 200 24(1 275 310 4/() 31X) 360 405 235 280 315 4/0 250 340 405 455 265 315 355 250 3(K) 375 445 565 290 350 395 3f10 350 420 505 570 330 395 445 350 400 455 545 615 355 425 480 400 5(X) 515 620 7(K) 405 485 545 500 600 575 69() 780 455 540 615 6(X) 700 630 755 855 500 595 675 70(1 750 655 785 885 SIS 620 700 750 8(1) 680 815 920 535 645 725 8(X) 9(X) 730 870 985 58() 700 785 90() IIKX) 780 935 1055 625 750 845 l(XXI 1251) 89() 1065 1200 710 855 960 1250 151X) 980 1325 795 950 1075 ISM 1750 1(170 1280 1445 875 1050 1185 1750 2(XX) 1155 1385 156() 960 1150 1335 2(KW) CORRECTION FACTORS Ambient Temp. For ambient lemperalures other than 30°C($6°F),mul(ipl} the allowable ampacities shown above by the appropriate factor Ambient Temp. CQ shown below. (•Fl 21-25 1.08 1.05 1.04 1.08 1,04 70-77 26-30 1.(X) i.00 1.(X) 1.00 1.(K) LW 78-86 31-35 0.91 0.94 0.96 0,91 0.94 0.96 87-95 36-40 0.82 0.88 0,91 0.82 0.88 0.91 96-104 41-15 0.71 0.82 0.87 0.71 0.82 0.87 105-113 46-50 0.58 0.75 0.82 0.58 0.75 (1.82 114-122 51-55 0.41 0.67 0.76 0.41 0.67 0.76 123-131 56-60 - 0.58 0.71 - 0.58 0.71 132-140 61-70 0.33 0.58 0,33 0.58 141-158 71-80 - - 0.41 - - 0.41 159-176 See 240.4(D), 2008 Edition NATIONAL ELECTRICAL CODE 70-149 310.15 ARTICLE 310-CONDUCTORS FOR GENERAL WIRING Table 310.18 Allowable Ampacities of Insulated Conductors Rated 0 Through 2000 Volts, 150°C Through 250°C (302°F Through 482°F). Not More Than Three Current-Carrying Conductors in Raceway or Cable, Based on Ambient Air Temperature of 40°C (104°F) Temperature Rating of Conductor[See Table 310.13(A).] 150-C(302°F) 200°C(392°F) 250°C(482°F) 150°C(302°F) Types FEP,FEPB, Type Z PFA,SA Types PFAH,TFE Type Z NICKEL OR ALUMINUM OR NICKEL-COATED COPPER-CLAD Size AWG or kemil COPPER COPPER ALUMINUM Size A4VG or kcmil 14 34 36 39 -- 14 12 43 45 54 30 12 10 55 60 73 44 10 8 76 83 93 57 8 6 96 110 117 75 6 4 120 125 148 94 4 3 143 152 166 109 3 2 160 171 191 124 2 1 186 197 215 145 1 110 215 229 244 169 1/0 210 251 260 273 198 2/0 310 288 297 308 227 310 410 1 332 346 1 361 1 260 1 410 CORRECTION FACTORS Ambient Temp.CC) For ambient temperatures other than 40°C(104°F),multiply the allowable ampacities shown Ambient Temp.(°F) above by the appropriate factor shown below. 41-50 0.95 0.97 0.98 0.95 105-122 51-60 0.90 0.94 0.95 0.90 123-140 61-70 0.85 0.90 0.93 0.85 141-158 71-80 0.80 0.87 0.90 0.80 159-176 81-90 0.74 0.83 0.87 0.74 177-194 91-100 0.67 0.79 0.85 0.67 195-212 101-120 0.52 0.71 0.79 0.52 213-248 121-140 0.30 0.61 0.72 0.30 249-284 141-160 - 0.50 0.65 - 285-320 161--180 - 0.35 0.58 - 321-356 181-200 - - 0.49 - 357-392 201-225 - - 0.35 - 393-437 70-t5O NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 310-CONDUCTORS FOR GENERAL WIRING 310.15 Table 310.19 Allowable Ampacities of Single-Insulated Conductors, Rated 0 Through 2000 Volts, 150°C Through 250°C (302°F Through 482°F), in Free Air, Based on Ambient Air Temperature of 40°C (104°F) Temperature Rating of Conductor(See Table 310.13(A).] 150°C (302°F) 200°C(392°F) 250°C(482°F) 150-C (302°F) Types FEP, Type Z FF,PB,PFA,SA Types PFAH,TFE Type Z ALUMINUM OR NICKEL,OR COPPER-CLAD Size AWG or kemil COPPER NICKEL-COATED COPPER ALUMINUM Size AWG or kemil 14 46 54 59 - 14 12 60 68 78 47 12 E❑ 80 90 107 63 1() 8 106 124 142 83 8 6 155 165 205 112 6 4 190 220 278 148 4 3 214 252 327 170 3 2 255 293 381 198 2 1 293 344 440 228 1 ]A) 339 399 532 263 Ito 211) 390 467 591 305 2/0 3A) 451 546 708 351 310 410 529 629 830 4]l 410 CORRECTION FACTORS Ambient Temp.CC) For ambient temperatures other than 40°C(104°F),multiply the allowable ampacities shown Ambient Temp.(°F) above by the appropriate factor shown below. 41-51) 0.95 0.97 0.99 0.95 105-122 51-61) 0.90 0.94 0.95 0.90 123-140 61-70 0.85 0.90 0.93 0.85 141-158 71-80 0.80 0.87 0.90 0.80 159-176 81-90 0.74 0.83 0.87 0.74 177-194 91-100 0.67 0.79 0.85 0.67 195-212 101-120 0.52 0.71 0.79 0.52 213-248 21 140 0.30 O.61 0.72 0.30 249-284 141-160 - 0.50 0.65 - 285-320 161-180 - 0.35 0.58 - 321-356 181-200 - 0.49 - 357-392 201-225 - - 0.35 - 393-437 2008 Edition NATIONAL ELECTRICAL CODF 70-151 310.15 ARTICLE 310 CONDUCTORS FOR GENERAL WIRING Table 310.20 Ampacities of Not More Than Three Single Insulated Conductors,Rated 0 Through 2000 Volts,Supported on a Messenger,Based on Ambient Air Temperature of 40°C (104°F) Temperature Rating or Conductor[See Table 310.13(A).] 75°C (167°F) 90°C(194°F) 75°C(167°F) 90'C(194°F) Types MI,THHN, THHW,THW-2, THWN-2,RHH, Types THHN,THHW, Types RHW,THHW, RHW-2,USE-2, Types RHW,THW, RUH,XHHW,RHW-2, THW,THWN, XHHW,XHHW-2, THWN,THHW, XHHW-2,THW-2, XHHW,ZW ZW-2 XHHW THWN-2,USE-2,ZW-2 Size AWG or kcmil COPPER ALUMINUM OR COPPER-CLAD ALUMINUM Size AWG or kcmil 8 57 66 44 51 8 6 76 89 59 69 6 4 101 117 78 91 4 3 118 138 92 107 3 2 135 158 106 123 2 158 185 123 144 1 110 183 214 143 167 110 210 212 247 165 193 210 310 245 287 192 224 310 410 287 335 224 262 410 250 320 374 251 292 250 300 359 419 282 328 300 350 397 464 312 364 350 400 430 503 339 395 400 500 496 580 392 458 500 600 553 647 440 514 600 700 610 714 488 570 700 750 638 747 512 598 750 800 660 773 532 622 800 900 704 826 572 669 900 1000 1 748 1 879 1 612 1 716 1 1000 CORRECTION FACTORS Ambient Temp.(°C) For ambient temperatures other than 40°C(104°F),multiply the allowable ampacities shown Ambient Temp.OF) above by the appropriate Factor shown below. 21-25 1.20 1.14 1.20 1.14 70-77 26-30 1.13 1.10 1.13 1.10 79-86 31-35 1.07 1.05 1.07 1.05 88-95 36-40 1.00 1.00 1.00 1.00 97-104 41-45 0.93 0.95 0.93 0.95 106-113 46-50 0.85 0.89 0.85 0.89 115-122 51--55 0.76 0.84 0.76 0.84 124-131 56-60 0.65 0.77 0.65 0.77 133-140 61-70 0.38 0.63 0.38 0.63 142-158 71-80 - 0.45 -- 0.45 160-176 70-152 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 310—CONDUCTORS FOR GENERAL WIRING 310.15 Table 310.21 Ampacities of Bare or Covered Conductors in Free Air,Based on 40°C (1{14°F)Ambient, 80°C (176°F)Total Conductor Temperature, 610 mm/sec (2 ft/sec) Wind Velocity Copper Conductors AAC Aluminum Conductors Bare Covered Bare Covered AWG or AWG or AWG or AWG or kcmil Amperes kcmil Amperes kcmil Amperes kcmil Amperes 8 98 8 103 8 76 8 80 6 124 6 130 6 96 6 101 4 155 4 163 4 121 4 127 2 209 2 219 2 163 2 171 l/0 282 1/0 297 1/0 220 110 231 210 329 210 344 210 255 210 268 310 382 310 401 310 297 3/0 312 410 444 410 466 4/0 346 4/0 364 250 494 250 519 266.8 403 266.8 423 3X0 556 300 584 336.4 468 336.4 492 500 773 500 812 397.5 522 397.5 548 750 1000 750 1050 477.0 588 477.0 617 1000 1193 1000 1253 556.5 650 556.5 682 — — 636.0 709 636.0 744 — — — 795.0 819 795.0 860 — — — 954.0 920 — - - — 1033.5 968 1033.5 1017 — -- 1272 1103 1272 1201 — — -- 1590 1267 1590 1381 — — — 2000 1454 2000 1527 2008 Edition NATIONAL.ELECTRICAL CODE 70-153 310.60 ARTICLE 310 CONDUCTORS FOR GENERAL WIRING 310.60 Conductors Rated 2001 to 35,000 Volts. with shields grounded at one point only. Where shields are grounded at more than one point, ampacities shall be adjusted (A) Definitions. to take into consideration the heating due to shield currents. Electrical Ducts. As used in Article 310, electrical ducts shall include any of the electrical conduits recognized in (2) Burial Depth of Underground Circuits. Where the Chapter 3 as suitable for use underground; other raceways burial depth of direct burial or electrical duct bank circuits round in cross section, listed for underground use, and em- is modified from the values shown in a figure or table, bedded in earth or concrete. ampacities shall be permitted to be modified as indicated in (C)(2)(a) and (C)(2)(b). Thermal Resistivity. As used in this Code, the heat trans- fer capability through a substance by conduction. It is the (a) Where burial depths are increased in part(s) of an reciprocal of thermal conductivity and is designated Rho electrical duct tun, no decrease in ampacity of the conductors and expressed in the units 'C-cm/watt. is needed, provided the total length of parts of the duct run increased in depth is less than 25 percent of the total tun (B) Ampacities of Conductors Rated 2001 to 35,000 length. Volts. Ampacities for solid dielectric-insulated conductors (b) Where burial depths are deeper than shown in a shall be permitted to be determined by tables or under en- specific underground ampacity table or figure, an ampacity gineering supervision, as provided in 310,60(C) and (D). derating factor of 6 percent per 300-mm (1-ft) increase in (1) Selection of Ampacity. Where more than one calcu- depth for all values of rho shall be permitted. lated or tabulated ampacity could apply for a given circuit No rating change is needed where the burial depth is length, the lowest value shall be used. decreased. Exception: Where two different ampacities apply to adja- (3) Electrical Ducts in Figure 310.60.At locations where cent portions of a circuit, the higher ampacity shall be electrical ducts enter equipment enclosures from under permitted to be used beyond the point of transition, a dis- ground, spacing between such ducts, as shown in Figure Lance equal to 3.0 m (10 ft) or 10 percent of the circuit 310.60, shalt be permitted to be reduced without requiring length figured at the higher ampacity, whichever is less. the ampacity of conductors therein to be reduced. FPN: See 110.40 for conductor temperature limitations due to termination provisions. (4) Ambients Not in Tables. Ampacities at ambient tem- peratures other than those shown in the tables shall be de- (C) Tables. Ampacities for conductors rated 2001 to termined by means of the following formula: 35,000 volts shall be as specified in the Ampacity Table 310.67 through Table 310.86. Ampacities at ambient tem- JC C_7A,—A 7D peratures other than those shown in the tables shall be de- I= 1` _7AL_A 7D termined by the formula in 310.60(C)(4). FPN No. 1: For ampacities calculated in accordance with where: 310.60(B), reference IEEE 835-1994 (IPCEA Pub. No. P46-426), Standard Power Cable Ampacity Tables, and the It = ampacity from tables at ambient TA, references therein for availability of all factors and constants. Iz = ampacity at desired ambient TA, FPN No. 2: Ampacities provided by this section do not take TC = conductor temperature in degrees Celsius (°C) voltage drop into consideration. See 210.19(A), FPN No. 4, TAI = surrounding ambient from tables in degrees for branch circuits and 215.2(A),FPN No. 2, for feeders. Celsius (°C) (1) Grounded Shields.Ampacities shown in Table 310.69, TA = desired ambient in degrees Celsius (°C) Table 310.70, Table 310.81, and Table 310.82 are for cable ATD = dielectric loss temperature rise 70-151 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 310—CONDUCTORS FOR GENERAL WIRING 310.60 �'. E ODetail i a - �D E E^? f/, 290 mm 290 mm $' E'c (11.5 in.x 11.5 in.) 190 mm(7.5 in.) 8 C Electrical duct bank Detail 2 One electrical duct 475 mm x 475 mm (19 in.x 19 in.) 190 mm(7.5 in.) Electrical duct bank Three electrical ducts Detail 3 or 475 mm x 675 mm v v (19 in.x 27 in.) Electrical duct bank T a Six electrical ducts or 190 mm 190 mm (7.5 in.) (7.5 in.) 675 mm x 290 mm o� o (27 in.x 11.5 in.) E ° Electrical duct bank 0 Three electrical ducts 190 mm 190 mm (7.5 in.) (7.5 in.) 675 mm x 475 mm (27 in.x 19 in.) Electrical duct bank Six electrical ducts 600 mm 600 mm (24 in.) } (241n.) Detail 5 Detail 6 Detail 7 Detail B Buried 3 Buried 3 Buried lriplexed Buried triplexed conductor conductor cables(1 circuit) cables(2 circuits) cable cables 190 mm 190 mm 190 mm 190 mm 190 mm 190 mm (7.5 in.) (7.5 in.) (7.5 in.) (7.5 n.) 600 mm (7.5 in.) (7.5 in.) 4 in.) Detail 9 Detail 10 Buried single-conductor Buried single-conductor cables(1 circuit) cables(2 circuits) Legend Note: Minimum burial deplhs to top electrical ducts or cables shall be Backlill(earth or concrete) in accordance with 300.50.Maximum depth to the top of electrical duct banks shall be 750 mm(30 in.)and maximum depth to the top O Electrical duct of direct buried cables shall be 900 mm(36 in.). • Cable or cables Figure 310.60 Cable Installation Dimensions for Use with Table 310.77 Through Table 310.86. 2008 Edition NATIONAL ELECTRICAL CODE 70-155 310.60 ARTICLE 310—CONDUCTORS FOR GENERAL WIRING (D) Engineering Supervision. Under engineering supervi- Table 310.68 Ampacities of Insulated Single Aluminum sion, conductor ampacities shall be permitted to be calcu- Conductor Cables Triplexed in Air Based on Conductor Temperatures of 901C (194'F) and 105'C (221'F) and toted by means of the fallowing general formula: Ambient Air Temperature of 40°C (104°F) ('1A+AI7)) Temperature Rating of Conductor[See Table I= 310.13(C).] 2001-5000 Volts 5001-35,000 Volts Ampacity Ampacity where: TC = conductor temperature in °C Conductor 105°C 105°C Size 90°C (221°F) 90°C (221°F) TA = ambient temperature in °C (AWG (194°F) Type (194°F) Type OTD = dielectric lass temperature rise or kemil) Type MV-90 MV-105 Type MV-90 MV-105 RDC = do resistance of conductor at temperature TC 8 50 57 -- -- YC = component ac resistance resulting from skin 6 70 77 75 84 effect and proximity effect 4 90 100 100 110 p y 2 125 135 130 150 RCA = effective thermal resistance between conductor 1 145 160 150 175 and surrounding ambient 110 170 185 175 200 210 195 215 200 230 FPN: See Annex B for examples of formula applications. 310 225 250 230 265 410 265 290 270 305 250 295 325 300 335 Ampacities of Insulated Single Copper 350 365 405 370 415 Table 310.67 Am p g PP 500 460 510 460 515 Conductor Cables Triplexed in Air Based on Conductor 750 600 665 590 660 Temperatures of 90°C (194°F) and 105°C (221°F) and 1000 715 800 700 780 Ambient Air Temperature of 40°C (104°F) Temperature Rating of Conductor[See Table Table 310.69 Ampacities of Insulated Single Copper 310.13(C).] Conductor Isolated in Air Based on Conductor Temperatures 2001-5000 Volts 5001-35,000 Volts of 90°C (194°F) and 105°C (221°F) and Ambient Air Ampacity Ampacity Temperature of 40'C (104-F) Conductor 105°C 105°C Temperature Rating of Conductor[See Table 310.13(0).] Size 90°C (221°F) 90°C (221°F) (AWG {194°F} Type (194°F) Type 2001-5000 Volts 5001-15,000 15,001-35,000 or kemil) Type MV-90 MV-105 Type MV-90 MV-105 Ampacity Volts Ampacity Volts Ampacity 8 65 74 — — Conductor 90°C 105°C 90°C 105°C 90°C 105°C 6 90 99 100 110 Size (194°F) (221°F) (194°F) (221°F) (194°F) (221°F) 4 120 130 130 140 {AWG Type Type Type Type Type Type 2 160 175 170 195 or kcmil) MV-90 MV-105 MV-90 MV-105 MV-90 MV-105 1 185 205 195 225 8 83 93 -- -- — — 110 215 240 225 255 6 110 120 110 125 — — 210 250 275 260 295 4 145 160 150 165 — — 310 290 320 300 340 2 190 215 195 215 — — 410 335 375 345 390 1 225 250 225 250 225 250 250 375 415 380 430 110 260 290 260 290 260 290 350 465 515 470 525 210 300 330 300 335 300 330 500 580 645 580 650 310 345 385 345 385 345 380 750 750 835 730 820 410 400 445 400 445 395 445 1000 880 980 850 950 250 445 495 445 495 440 490 350 550 615 550 610 545 605 500 695 775 685 765 680 755 750 900 1000 885 990 870 970 1000 1075 1200 1060 1185 1040 1160 1250 1230 1370 1210 1350 1185 1320 1500 1365 1525 1345 1500 1315 1465 1750 1495 1665 1470 1640 1430 1595 2000 1605 1790 1575 1755 1535 1710 70-156 NATIONAL.ELECTRICAL CODE 2008 Edition ARTICLE 310—CONDUCTORS FOR GENERAL WIRING 310.60 Table 3I0.70 Ampacities of Insulated Single Aluminum Table 310.72 Ampacities of an Insulated Three-Conductor Conductor Isolated in Air Based on Conductor Temperatures Aluminum Cable Isolated in Air Based on Conductor of 90°C (194°F) and 105°C (221°F) and Ambient Air Temperatures of 90°C (194°F) and I05°C (221°F) and Temperature of 40°C (104°F) Ambient Air Temperature of WC (]04°F) Temperature Rating of Conductor[See Table 310.13(C).]] Temperature Rating of Conductor]See Table 2001--5000 Volts 5001-15,000 15,001-35,000 310.13(C).] Ampaci(v Volts Ampacity, Volts Ampacity 5001-35,000 Volts Conductor 90°C 105°C 90°C 105°C 9(1°C 105°C 2001-5000 Volts Ampacity Ampacity Size (194°F) (221°F) (194°F) (221°F) (194°F) (221°F) Conductor 105°C 105°C (MVG Type Type Type Type Type Type Size 90°C (221°F) 90°C (221°F) or kemil) MV-90 MV-105 MV-90 NIV-105 MV-90 MV-105 (AWG (194°F) Type (194°F) Type 8 64 71 — — — — or kcmil) Type MV-90 MV-105 Type MV-90 MV-105 6 85 95 87 97 — — 9 46 51 4 115 125 115 1311 — — 6 61 68 72 80 2 150 165 150 170 4 91 90 95 105 1 175 195 175 195 175 195 2 110 120 125 145 1/0 21H1 225 20) 225 200 225 l 125 140 145 165 2/O 230 260 235 260 230 260 W 145 160 170 185 310 270 3(H) 270 3(H) 270 300 21(1 170 185 I EH) 215 410 310 351) 310 350 310 345 310 195 215 220 245 250 345 385 345 395 345 380 410 225 250 255 285 350 430 490 430 480 430 475 5(H) 545 605 535 600 530 590 250 250 280 280 315 750 71() 790 7(H) 780 695 765 350 310 345 345 395 500 395 430 425 475 1000 855 950 840 940 825 920 750 495 550 540 600 1250 980 1095 970 1080 950 1055 1000 595 650 635 705 1500 1105 1230 1085 1215 1060 1190 1750 1215 1355 1195 1335 1165 1300 2(HX) 1320 1475 1295 1445 1265 1410 Table 310.73 Ampacities of an Insulated 'lYiplexed or Three Single-Conductor Copper Cables in Isolated Conduit in Air Table 310.71 Ampacities of an Insulated Three-Conductor Based on Conductor Temperatures of 90°C (.194°F) and Copper Cable Isolated in Air Based on Conductor 105°C (221°F)and Ambient Air Temperature of 40°C Temperatures of 90°C (194°F) and 105°C (221°F) and (104°F) Ambient Air Temperature of 40°C (104°F) Temperature Rating of Conductor[See Table Temperature Rating of Conductor[See Table 310.13(C).] 310.13{C).] 2001-5000 Volts 5001-35,000 Volts 2001-5000 Volts 5001-35,000 Volts Ampacity Ampacity Ampacity Ampacity Conductor 90°C 90°C Conductor 105°C 105°C Size (194°F) 105°C (194°F) 105°C 90°C (221°F) (ANVG Size (221°F) Type (221°F)Type Type (221°F)Type (AWG (194°f-) Type 90°C (194°F) Ttpe or kemil) MV-90 MV-105 MV-90 MV-105 or kemil) Type MV-90 MV-105 Type NIV-90 NIV-105 8 55 61 — — 9 59 66 — — 6 75 84 83 93 6 79 88 93 1{)5 4 97 110 110 120 4 105 115 120 135 2 130 145 )50 165 2 140 154 165 185 1 155 175 17{) 190 1 160 180 185 210 I/O 190 200 195 215 210 205 225 225 255 1/0 195 205 215 240 310 240 270 260 29(} 2/0 215 241) 245 275 3/O 250 28(} 285 315 410 290 305 295 331} 410 285 320 325 360 250 M5 355 330 365 350 385 430 395 440 250 320 355 360 400 500 475 530 480 535 350 395 440 435 490 750 600 665 595 655 500 495 545 535 600 1 W 690 770 675 755 750 615 695 670 745 1M() 705 790 770 86{) 2008 Edition NATIONAL,ELECTRICAL CODE 70-157 310.60 ARTICLE 310 CONDUCTORS FOR GENERAL WIRING Table 310.74 Ampacities of an Insulated Triplexed or Three Table 310.76 Ampacities of an Insulated Three-Conductor Single-Conductor Aluminum Cables in Isolated Conduit in Aluminum Cable in Isolated Conduit in Air Based on Air Based on Conductor Temperatures of 90°C (194°F) and Conductor Temperatures of 90°C (194°F) and 105°C (221°F) 105°C (221°F) and Ambient Air Temperature of 40°C and Ambient Air Temperature of 40°C (104°F) (104°F) Temperature Rating of Conductor[See Table Temperature Rating or Conductor[See Table 310.13(C).] 310.13(0).1 2001-5000 Volts 5001-35,000 Volts 2001-5000 Volts 5001-35,000 Volts Ampacity Ampacity Ampacity Ampacity Conductor 105°C 105°C 105°C 105°C Size 90°C (221°F) 90°C (221°F) Conductor 90°C (221°F) 90°C (221°F) (AWG (194°F) Type (194°F) Type Size(AWG (194°F) Type (194°F) Type or kcmil) Type MV-90 MV-105 Type MV-90 MV-105 or kcmil) Type MV-90 MV-105 Type MV-90 MV-105 8 41 46 — — 8 43 48 --- — 6 53 59 64 71 6 58 65 65 72 4 71 79 84 94 4 76 85 84 94 2 96 105 115 125 2 100 115 115 130 1 110 125 130 145 l 120 135 130 150 110 130 145 150 170 I/O 140 155 150 170 7J0 150 165 170 190 2/0 160 175 175 200 310 170 190 195 220 3/0 190 210 200 225 410 200 225 225 255 4/0 215 240 230 260 250 220 245 250 280 250 250 280 255 290 350 275 305 305 340 350 305 340 310 350 500 340 380 380 425 500 380 425 385 430 750 430 480 470 520 750 490 545 485 540 1000 505 561) 550 615 1000 580 645 565 640 Table 310.75 Ampacities of an Insulated Three-Conductor Copper Cable in Isolated Conduit in Air Based on Conductor Temperatures of 90°C (194°F) and 105°C (221°F) and Ambient Air Temperature of 40°C (104°F) Temperature Rating of Conductor[See Table 5001-35,000 Volts 2001-5000 Volts Ampacity Ampacity Conductor 105°C 105°C Size 90°C (221°F) 90°C (221°F) (AWG (194°F) Type (194°F) Type or kcmil) Type MV-90 MV-I05 Type MV-90 MV-105 8 52 58 — — 6 69 77 83 92 4 91 100 105 120 2 125 135 145 165 l 140 155 165 185 1/0 165 185 195 215 2/0 190 210 220 245 310 220 245 250 280 4/0 255 285 290 320 250 280 315 315 350 350 350 390 385 430 500 425 475 470 525 750 525 585 570 635 1000 590 660 650 725 70-158 NATIONAL ELEMRICAL CODE 2008 Edition ARTICLE 310—CONDUCTORS FOR GENERAL WIRING 310.60 Table 310.77 Ampacities of Three Single-Insulated Copper Table 310.78 Ampacities of Three Single-Insulated Conductors in Underground Electrical Ducts (Three Aluminum Conductors in Underground Electrical Ducts Conductors per Electrical Duct) Based on Ambient Earth (Three Conductors per Electrical Duct) Based on Ambient Temperature of 20°C (68°F), Electrical Duct Arrangement Earth Temperature of 20°C (68°F),Electrical Duct per Figure 310.60, 100 Percent Load Factor,Thermal Arrangement per Figure 310.60, 100 Percent Load Factor, Resistance (RHO) of 90, Conductor Temperatures of 90°C Thermal Resistance (RHO) of 90, Conductor Temperatures (194°F) and 105°C (221°F) of 90°C (194°F)and 105°C (221°F) Temperature Rating of Conductor[See Table Temperature Rating of Conductor[See Table 310.13(C).] 310.13(C).] 2001-5000 Volts 5001-35,000 Volts 2001-5000 Volts 5001-35,000 Volts Ampacity Ampacity Ampacity Ampacity Conductor 90°C 105°C 90°C 105°C Conductor 90°C 105°C 90°C 105°C Size (194°F) (221°F) (194°F) (221°F) Size (194°F) (221°F) (194°F) (221°F) (AWG Type Type Type Type (AWG Type Type Type pe or kcmil) MV-90 MV-105 MV-90 MV-105 or kcmil) MV-90 MV-105 MV-90 MV'-105_ One Circuit(See Figure One Circuit(See Figure 310.60, Detail 1.) 310.60,Detail 1.) 8 64 69 — — 8 50 54 — 6 85 92 90 97 6 66 71 70 75 4 110 120 115 125 4 86 93 91 98 2 145 155 155 165 2 115 125 120 130 1 170 1811 175 185 l 130 140 135 145 U0 195 210 2(10 215 110 150 160 155 165 210 221) 235 230 245 210 170 185 175 190 310 250 270 260 275 310 195 210 200 215 410 290 310 295 315 410 225 245 230 245 250 320 345 325 345 250 250 270 250 270 350 385 415 390 415 350 305 325 305 330 500 470 505 465 500 5(x1 370 400 370 400 750 585 630 565 610 750 470 505 455 490 1000 670 720 640 690 IOW 545 590 525 565 Three Circuits(See Figure Three Circuits(See Figure 310.60,Detail 2.) 310.60,Detail 2.} 8 56 60 — 8 44 47 — — 6 73 79 77 83 6 57 61 60 65 4 95 1W 99 105 4 74 80 77 83 2 125 130 130 135 2 96 105 1W 105 l 140 15(} 145 155 1 110 120 110 120 110 160 175 165 175 110 125 135 125 140 210 185 195 185 200 210 145 155 145 155 310 210 225 210 225 310 160 175 165 175 410 235 255 240 255 4/0 185 200 185 200 250 260 280 260 280 250 205 220 200 220 350 315 335 310 330 350 245 265 245 260 500 375 405 370 395 5W 295 320 290 315 750 460 495 440 475 750 370 395 355 385 IOW 525 565 495 535 1000 425 460 405 440 Six Circuits(See Figure Six Circuits(See Figure 310.60,Detail 3.) 310.60,Detail 3.) 8 48 52 — — 8 38 41 — — 6 62 67 64 68 6 48 52 50 54 4 80 86 82 88 4 62 67 64 69 2 105 110 105 115 2 80 86 80 88 1 115 125 120 125 l 91 98 90 99 1/0 135 145 135 145 1/0 105 110 105 110 2/0 150 160 150 165 210 115 125 115 125 310 170 185 170 185 310 135 145 130 145 410 195 210 1(X) 205 410 150 165 150 160 250 210 225 210 225 250 165 180 165 175 350 250 270 245 265 350 195 210 195 210 5(x) 300 325 290 310 500 240 255 230 250 750 365 395 350 375 750 290 315 280 305 I(x10 410 445 390 415 1000 335 360 320 345 2008 Edition NATIONAL ELECTRICAL CODE 70-159 310.60 ARTICLE 310—CONDUCTORS FOR GENERAL WIRING Table 310.79 Ampacities of Three Insulated Copper Table 310.80 Ampacities of Three Insulated Aluminum Conductors Cabled Within an Overall Covering Conductors Cabled Within an Overall Covering (Three-Conductor Cable) in Underground Electrical Ducts (Three-Conductor Cable) in Underground Electrical Ducts (One Cable per Electrical Duct) Based on Ambient Earth (One Cable per Electrical Duct) Based on Ambient Earth Temperature of 20°C (68°F),Electrical Duct Arrangement Temperature of 20°C(68'F),Electrical Duct Arrangement per Figure 310.60, 100 Percent Load Factor,Thermal per Figure 310.60, 100 Percent Load Factor,Thermal Resistance (RHO) of 90, Conductor Temperatures of 90°C Resistance (RHO) of 90, Conductor Temperatures of 90°C (194°F) and 105°C (221°C) (194°F) and 105°C (221°C) Temperature Rating of Conductor[See Table Temperature Rating of Conductor[See Table 310.13(C).] 310.13(C).] 2001-5000 Volts 5001-35,000 Volts 2001-5000 Volts 5001-35,000 Volts Ampacity Ampacity Ampacity Ampacity Conductor 90°C 105°C 90°C 105°C Conductor 90°C 105°C 90°C I05 1C Size (194°F) (221°F) (194°F) (221°F) Size (194°F) (221°F) (194°F) (221°F) (AWG Type Type 'Type Type (AWG Type Type Type Type or kcmil) MV-910 MV-105 MV-90 MV-105 or kemil) MV-90 MV-105 MV-90 MV-105 One Circuit(See Figure One Circuit(See Figure 310.60,Detail 1.) 310.60,Detail 1.) 8 59 64 --- — 8 46 50 -- -- 6 78 84 88 95 6 61 66 69 74 4 100 110 115 125 4 80 86 89 96 2 135 145 150 160 2 105 110 115 125 1 155 165 170 185 1 120 130 135 145 110 175 190 195 210 1/0 140 150 150 165 210 200 220 220 235 210 160 170 170 185 310 230 250 250 270 3/0 180 195 195 210 4/0 265 285 285 305 4/0 205 220 220 240 250 290 315 310 335 250 230 245 245 265 350 355 380 375 400 350 280 310 295 315 500 430 460 450 485 500 340 365 355 385 750 530 570 545 585 750 425 460 440 475 1000 600 645 615 660 1000 495 535 510 545 Three Circuits(See Figure Three Circuits(See Figure 310.60,Detail 2.) 310.60,Detail 2.) 8 53 57 — — 8 41 44 — — 6 69 74 75 81 6 54 58 59 64 4 89 96 97 105 4 70 75 75 81 2 115 125 125 135 2 90 97 100 i05 1 135 145 140 155 1 105 110 110 120 110 150 165 160 175 1/0 120 125 125 135 2/0 170 185 185 195 210 135 145 140 155 3/0 195 210 205 220 310 155 165 160 175 410 225 240 230 250 4/0 175 185 180 195 250 245 265 255 270 250 190 205 200 215 350 295 315 305 325 350 230 250 240 255 500 355 380 360 385 500 280 300 285 305 750 430 465 430 465 750 345 375 350 375 Moo 485 520 485 515 1000 400 430 400 430 Six Circuits(See Figure Six Circuits(See Figure 310.60,Detail 3.) 310.60,Detail 3.) 8 46 50 — — 8 36 39 -- -- 6 60 65 63 68 6 46 50 49 53 4 77 83 81 87 4 60 65 63 68 2 98 105 105 110 2 77 83 80 86 1 110 120 115 125 l 87 94 90 98 1/0 125 135 130 145 1/0 99 105 105 110 2/0 145 155 150 160 210 110 120 115 125 310 165 175 170 180 310 130 140 130 140 4/0 185 200 190 200 4/0 145 155 150 160 250 200 220 205 220 250 160 170 160 170 350 240 270 245 275 350 190 205 190 205 500 290 310 290 305 500 230 245 230 245 750 350 375 340 365 750 280 305 275 295 1000 390 420 380 405 1000 320 345 315 335 70-160 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 310—CONDUCTORS FOR GENERAL WIRI14G 310.60 Table 310.81 Ampacities of Single Insulated Copper Table 310.82 Ampacities of Single Insulated Aluminum Conductors Directly Buried in Earth Based on Ambient Conductors Directly Buried in Earth Based on Ambient Earth Temperature of 20°C (68°F),Arrangement per Figure Earth Temperature of 20°C (68°F),Arrangement per Figure 310.60, 100 Percent Load Factor,Thermal Resistance (RHO) 310.60, 100 Percent Load Factor,Thermal Resistance (RHO) of 90, Conductor Temperatures of 90°C (194°F) and 105°C of 90, Conductor Temperatures of 90°C (194°F)and 105°C (221°C) (221°F) Temperature Rating of Conductor[See Table Temperature Rating of Conductor[See Table 310.13(C).] 310.13(0).1 2001-5000 Volts 5001-35,000 Volts 2001-5400 Volts 5001-35,000 Volts Ampacity Ampacity Ampacity Ampacity Conductor 90°C 105°C 901C 105°C Conductor 90°C 105°C 90°C 105°C Size (194°F) (221°F) (194°F) (221°F) Size (194°F) (221°F) (194°F) (221°F) (AWG Type Type Type Type (AWG TyPe Type Ty1R Type or kemil) MV-90 MV-105 NIV-90 MV-105 or kcmil) MV-90 MV-105 MV-90 MV-105 One Circuit,Three One Circuit,Three Conductors(See Figure Conductors(See Figure 310.60, Detail 9.) 310.60,Detail 9.) 8 110 115 — 8 85 90 — — 6 140 I50 130 140 6 110 115 100 110 4 180 195 170 180 4 140 I50 130 140 2 230 250 210 225 2 180 195 165 175 1 260 280 240 260 1 205 220 185 200 1/0 295 320 275 295 1/0 230 250 215 230 210 335 365 310 335 2/0 263 285 245 260 310 385 415 355 380 3/0 300 320 275 295 410 435 465 405 435 410 340 365 315 340 250 470 510 440 475 250 370 395 345 370 350 570 615 535 575 350 445 480 415 450 500 690 745 650 700 500 540 580 510 545 750 845 910 805 865 750 665 720 635 680 1000 980 1055 930 1005 1000 780 840 740 795 Two Circuits, Two Circuits,Six Six Conductors(See Figure Conductors(See Figure 310.60, Detail 10.) 310.60,Detail 10.) 8 100 310 — 8 80 85 — — 6 130 140 120 130 6 100 110 95 100 4 165 180 160 170 4 130 140 125 130 2 215 230 195 210 2 165 180 155 165 1 240 260 225 240 1 190 200 175 190 1/0 275 295 255 275 1/0 215 230 200 215 2/0 310 335 290 315 2/0 245 260 225 245 310 355 380 330 355 3/0 275 295 255 275 410 400 430 375 405 4/0 310 335 290 315 250 435 470 410 440 250 340 365 320 345 350 520 560 495 530 350 410 440 385 415 500 630 680 600 645 500 495 530 470 505 750 775 835 740 795 750 610 655 580 625 1000 890 960 855 920 1000 710 765 680 730 2008 Edition NATIONAL ELECTRICAL CODF. 74-,161 310.60 ARTICLE 310--CONDUCTORS FOR GENERAL WIRING Table 310.83 Ampacities of Three Insulated Copper Table 310.84 Ampacities of Three Insulated Aluminum Conductors Cabled Within an Overall Covering Conductors Cabled Within an Overall Covering (Three-Conductor Cable),Directly Buried in Earth Based on (Three-Conductor Cable),Directly Buried in Earth Based on Ambient Earth Temperature of 20°C (68°F),Arrangement Ambient Earth Temperature of 20°C (68°F),Arrangement per Figure 310.60, 100 Percent Load Factor,Thermal per Figure 310.60, 100 Percent Load Factor,Thermal Resistance (RHO) of 90, Conductor Temperatures of 90°C Resistance(RHO) of 90, Conductor Temperatures of 90°C (194°F) and 105°C (221°F) (194°F) and 105°C (221°F) Temperature Rating or Conductor[See Table Temperature Rating of Conductor[See Table 310.13(C).1 31QJ3(Q.l 2001-5000 Volts 5001--35,000 Volts 2001-5000 Volts 5001-35,000 Volts Ampacity Ampacity Ampacity Ampacity Conductor 90°C 105°C 90°C 105°C Conductor 90°C 105°C 90°C 105°C Size (194°F) (221°F) (194°F) (221°F) Size (194°F) (221°F) (194°F) (221°F) (AWG Type Type Type Type (AWG Type Type Type Type or kcmil) MV-90 NIV-105 MV-90 MV--105 or kcmil) MV-90 MV-105 MV-90 MV-105 One Circuit(See Figure One Circuit(See Figure 310.60,Detail 5.) 310.60,Detail 5.) 8 85 89 — — 8 65 70 — — 6 105 115 115 120 6 80 88 90 95 4 135 150 145 155 4 105 115 115 125 2 180 190 185 200 2 140 150 145 155 1 200 215 210 225 1 155 170 165 175 110 230 245 240 255 110 180 190 185 200 210 260 280 270 290 210 205 220 210 225 310 295 320 305 330 310 230 250 240 260 410 335 360 350 375 410 260 280 270 295 250 365 395 380 410 250 285 310 300 320 350 440 475 460 495 350 345 375 360 390 500 530 570 550 590 500 420 450 435 470 750 650 700 665 720 750 520 560 540 880 1000 730 785 750 810 1000 600 650 620 665 Two Circuits(See Figure Two Circuits(See Figure 310.60,Detail 6.) 310.60,Detail 6.) 8 80 84 — — 8 60 66 — -- 6 100 105 105 115 6 75 83 80 95 4 130 140 135 145 4 100 110 105 115 2 165 180 170 185 2 130 140 135 145 1 185 200 195 210 1 145 155 150 165 110 215 230 220 235 110 165 180 170 185 210 240 260 250 270 210 190 205 195 210 310 275 295 280 305 310 215 230 220 240 410 310 335 320 345 410 245 260 250 270 250 340 365 350 375 250 265 285 275 295 350 410 440 420 450 350 320 345 330 355 500 490 525 500 535 500 385 415 395 425 750 595 640 605 650 750 480 515 485 525 1000 665 715 675 730 1000 550 590 560 600 70-162 NATIONAL ELECTRICAL CODE 2009 Edition ARTICLE- 310—CONDUCTORS FOR GENERAL WIRING 310.60 Table 310.85 Ampacities of Three Triplexed Single 1nsuIated Table 310.86 Ampacities of Three Triplexed Single Insulated Copper Conductors Directly Buried in Earth Based on Aluminum Conductors Directly Buried in Earth Based on Ambient Earth Temperature of 20°C (68°F),Arrangement Ambient Earth Temperature of 20°C (68°F),Arrangement per Figure 310.60, 100 Percent Load Factor,Thermal per Figure 310.60, 100 Percent Load Factor,Thermal Resistance (RHO) of 90, Conductor Temperatures 90°C Resistance(RHO) of 90, Conductor Temperatures 90°C (194'F)and 105°C (221°F) (194°F) and 105°C (221°F) Temperature Rating of Conductor[See Table Temperature Rating of Conductor[See Table 310.13(C).] 310.13(C).] 2001-5000 Volts 5001-35,000 Volts 2001-5000 Volts 5001--35,000 Volts Ampacity Ampacity Ampacity Ampacity Conductor 90°C 105°C 90°C 105°C Conductor 90°C 105°C 90°C 105°C Size (194°F) (221°F) (194°F) (221°F) Size 1194°F) (221°F) (194°F) (221°F) (AWG Type Type Type Type (AWG Type Type Tvpe Tyype or kcmil) MV-90 MV-105 MV-90 MV-105 or kemil) MV-90 MV-105 MV-90 MV-105 One Circuit,Three One Circuit,Three Conductors(See Figure Conductors(See Figure 310.60, Detail 7.) 310.60,Detail 7.) 8 90 95 — — 8 70 75 — 6 120 130 115 124) 6 90 100 90 95 4 150 165 150 160 4 120 130 115 125 2 195 205 190 205 2 155 165 145 155 l 225 240 215 230 l 175 190 165 175 110 255 270 245 260 110 201) 210 190 205 210 290 310 275 295 210 225 240 215 230 310 330 364) 315 340 310 255 275 245 265 410 375 405 360 385 410 290 310 280 305 250 410 445 390 410 250 320 350 305 325 350 490 580 470 505 350 385 420 370 4(M) 5(M) 590 635 565 005 500 465 5(111 445 480 750 725 780 685 740 750 580 625 550 590 1M0 825 885 770 830 1000 670 725 635 680 W,o Circuits,Six Two Circuits,Six Conductors(See Figure Conductors(See Figure 310.60,Detail 8.1 310.60,Detail 8.) 8 85 tX) — — 8 65 70 — — 6 111) 115 105 115 6 85 95 85 90 4 140 150 140 150 4 110 120 105 115 2 180 195 175 190 2 140 150 135 145 1 205 220 200 215 l 160 170 155 170 110 235 250 225 240 110 180 195 175 190 210 265 285 255 275 21O 205 220 200 215 310 300 320 290 315 310 235 250 225 245 410 340 365 325 350 410 265 285 255 275 250 370 395 355 380 250 290 31() 280 300 350 445 480 425 455 350 350 375 335 360 500 535 575 510 545 500 420 455 405 4.1.5 750 650 700 615 660 750 520 560 485 525 14MM) 740 795 690 745 1000 600 645 565 605 2008 Edition NATIONAL ELECTRICAL CODE 70_163 312.1 ARTICLE 312—CABINETS,CUTOUT BOXES,AND METER SOCKET ENCLOSURES in dry locations, through flexible tubing extending from the ARTICLE 312 last insulating support and firmly secured to the enclosure. Cabinets, Cutout Boxes, and Meter Socket Enclosures (C) Cables. Where cable is used, each cable shall be se- cured to the cabinet, cutout box, or meter socket enclosure. Exception: Cables with entirely nonmetallic sheaths shall 312.1 Scope. This article covers the installation and con- be permitted to enter the top of a surface-mounted enclo- struction specifications of cabinets,cutout boxes, and meter sure through one or more nonflexible raceways not less socket enclosures. than 450 mm (18 in.) and not more than 3.0 m (1Oft) in length, provided all of the following conditions are met: I. Installation (a) Each cable is fastened within 300 mm (12 in.), measured along the sheath, of the outer end of the raceway. 312.2 Damp and Wet Locations. In damp or wet Iota- (b) The raceway extends directly above the enclosure tions, surface-type enclosures within the scope of this ar- and does not penetrate a structural ceiling. title shall be placed or equipped so as to prevent moisture (c) A fitting is provided on each end of the raceway to or water from entering and accumulating within the cabinet protect the cable(s)from abrasion and the fittings remain or cutout box, and shall be mounted so there is at least accessible after installation. 6-mm (t/a-in.) airspace between the enclosure and the wall (d) The raceway is seated or plugged at the outer end or other supporting surface, Enclosures installed in wet lo- using approved means so as to prevent access to the enclo- cations shall be weatherproof. For enclosures in wet loca- sure through the raceway. tions, raceways or cables entering above the level of unin- (e) The cable sheath is continuous through the race- sulated live parts shall use fittings listed for wet locations. way and extends into the enclosure beyond the fitting not Exception: Nonmetallic enclosures shall be permitted to be less than 6 mm (!/4 in.). installed without the airspace on a concrete, masonry, tile, (}) The raceway is fastened at its outer end and at or similar surface. other points in accordance with the applicable article. (g) Where installed as conduit or tubing, the allowable FPN: For protection against corrosion, see 300.6. cable fill does not exceed that permitted for complete con- duit or tubing systems by Table 1 of Chapter 9 of this Code 312.3 Position in Wall. In walls of concrete, tile, or other and all applicable notes thereto. noncombustible material, cabinets shall be installed so that FPN: See Table 1 in Chapter 9, including Note 9, for al- the front edge of the cabinet is not set back of the finished lowable cable fill in circular raceways. See 310.15(B)(2)(a) surface more than 6 mm (t/a in.). In walls constructed of for required ampacity reductions for multiple cables In- wood or other combustible material, cabinets shall be flush stalled in a common raceway. with the finished surface or project therefrom. • 312.6 Deflection of Conductors. Conductors at terminals 312,4 Repairing Noncombustible Surfaces. Noncombus- or conductors entering or leaving cabinets or cutout boxes tible surfaces that are broken or incomplete shall be re- and the like shall comply with 312.6(A) through (C). paired so there will be no gaps or open spaces greater than 3 mm ('/s in.) at the edge of the cabinet or cutout box Exception: Wire-bending space in enclosures for motor employing a flush-type cover. controllers with provisions for one or two wires per termi- nal shall comply with 430.10(B). 312.5 Cabinets,Cutout Boxes,and Meter Socket Enclo- sures. Conductors entering enclosures within the scope of (A) Width of Wiring Gutters. Conductors shall not be this article shall be protected from abrasion and shall com- deflected within a cabinet or cutout box unless a gutter having ply with 312.5(A) through (C). a width in accordance with Table 312.6(A) is provided. Con- ductors in parallel in accordance with 310.4 shall be judged on (A) Openings to Be Closed.Openings through which con- the basis of the number of conductors in parallel. ductors enter shall be adequately closed. (B) Wire-Bending Space at Terminals. Wire-bending (B) Metal Cabinets, Cutout Boxes, and Meter Socket space at each terminal shall be provided in accordance with Enclosures. Where metal enclosures within the scope of 312.6(B)(1) or (8)(2). this article are installed with messenger-supported wiring, open wiring on insulators, or concealed knob-and-tube wir- (1) Conductors Not Entering or Leaving Opposite Wall. ing, conductors shall enter through insulating bushings or, Table 312.6(A) shall apply where the conductor does not 70-164 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 312—CABINETS,CUTOUT BOXES,AND METER SOCKET ENCLOSURES 312.10 Table 312.6(A) Minimum Wire-Bending Space at Terminals and Minimum Width of Wiring Gutters Wires per Terminal 1 2 3 Wire Size (AWG or q $ kemil) mm in. mm in. mm in. mm in. mm in. 14-10 Not specilied 8 6 38.1 11/ — — — — 4-3 50.8 2 — — — — — 2 63.5 21/ - 1 76.2 3 — — — — — — — 1/0-2/0 88.9 31/ 127 5 178 7 — — — — 3/0-4/0 102 4 152 6 203 8 — — — — 250 114 41/2 152 6 203 8 254 10 — — 300-350 127 5 203 8 254 10 305 12 — — 400-500 152 6 203 8 254 10 305 12 356 14 600-700 203 8 254 10 305 12 356 14 406 16 750--900 203 8 305 12 356 14 406 16 457 18 1000-1250 254 10 — — — 1500-2000 305 12 — — — — — — — Note: Bending space at terminals shall be measured in a straight line from the end of the lug or wire connector(in the direction that the wire leaves the terminal) to the wall. barrier,or obstruction. enter or leave the enclosure through the wall opposite its 312.7 Space in Enclosures. Cabinets and cutout boxes terminal. shall have sufficient space to accommodate all conductors (2) Conductors Entering or Leaving Opposite Wall. installed in them without crowding. Table 312.6(B) shall apply where the conductor does 312.8 Enclosures for Switches or Overcurrent Devices. enter or leave the enclosure through the wall opposite its Enclosures for switches or overcurrent devices shall not be terminal. used as junction boxes, auxiliary gutters,or raceways for con- Exception No. 1: Where the distance between the wall and ductors feeding through or tapping off to other switches or its terminal is in accordance with Table 312,60), a con- overcurrent devices, unless adequate space for this purpose is ductnr shall be permitted to enter or leave an enclosure provided.The conductors shall not fill the wiring space at any through the wall opposite its terminal, provided the con- cross section to more than 40 percent of the cross-sectional ductnr enters or leaves the enclosure where the gutter joins area of the space, and the conductors, splices, and taps shall an adjacent gutter that has a width that c•onforins to Table not fill the wiring space at any cross section to more than 312.6(8)for the conductor. 75 percent of the cross-sectional area of that space. Exception No. 2: A conductor not larger than 350 kenzil shall be permitted to enter Or leave an enclosure containing 312.9 Side or Back Wiring Spaces or Gutters. Cabinets only a meter socket(s) through the wall apposite its tenni- and cutout boxes shall be provided with back-wiring nal, provided the distance between the tenninal and the spaces, gutters, or wiring compartments as required by apposite wall is not less than that specified in Table 312.1 I(C) and (D). 312.60)and the terminal is a lay-in type, where the termi- nal is either of the fallowing: II. Construction Specifications (a) Directed toward the opening in the enclosure and within a 45 degree angle of directly facing the enclosure 312.10 Material. Cabinets, cutout boxes, and meter socket wall enclosures shall comply with 312.10(A) through (C). (b) Directly facing the enclosure wall and offset not (A) Metal Cabinets and Cutout Boxes. Metal enclosures greater than 50 percent of the bending space .specified in Table 312.6(A) within the scope of this article shall be protected both in- side and outside against corrosion. FPN: Offser is the distance measured along the enclosure wall from the axis of the centerline of the terminal to a line FPN: For information on protection against corrosion, see passing through the center of the opening in the enclosure. 300.6. (C) Conductors 4 AWG or Larger.Installation shall com- (B) Strength. The design and construction of enclosures ply with 300.4(G). within the scope of this article shall be such as to secure 2008 Edition NATIONAL.ELECTRICAL CODE 70-165 312.10 ARTICLE 312----CABINETS,CUTOUT BOXES,AND METER SOCKET ENCLOSURES Table 312.6(B) Minimum Wire-Bending Space at Terminals Wires per Terminal Wire Size(AWG or kcmil) 1 2 3 4 or More Compact Stranded AA-8000 Aluminum Alloy All Other Conductors Conductors (See Note 3.) mm in. mm in. mm in. mm in. 14-10 12--8 Not specified — — — — — 8 6 38.1 11/2 -- — — — 6 4 50.8 2 -- — — — 4 2 76.2 3 — — — -- — 3 1 76.2 3 — — — — — 2 110 88.9 3 - 1 2/0 114 41h — -- — — — 110 3/0 140 51/2 140 5/2 178 7 — — 2/0 410 152 6 152 6 190 71/2 — — 3/0 250 165° 61/? 165a 61h° 203 8 — — 4/0 300 178b 7h 190` 71/2` 216' 81/2a — — 250 350 216`' 81/2d 229`' 81/2d 254b 9e 254 10 300 400 254e 10` 254d l0d 279b lib 305 12 350 500 3050 12` 305` 12e 330` 130 356d 14d 400 600 330` 130 330` 13e 356e 140 381` 150 500 700-750 356` 140 356e 140 38le 150 406` 16e 600 800-900 381` 150 406` 16` 457` 180 4830 19e 700 1000 406° 16e 457e 180 508e 20` 559` 220 750 — 4320 170 483` 19` 5590 220 6100 240 800 — 457 18 508 20 559 22 610 24 900 — 483 19 559 22 610 24 610 24 1000 — 508 20 — — -- -- 1250 — 559 22 — — — 1500 — 610 24 — — — 1750 — 610 24 — — — — 2000 — 610 24 — — — — 1. Bending space at terminals shall be measured in a straight line from the end of the lug or wire connector in a direction perpendicular to the enclosure wall. 2. For removable and lay-in wire terminals intended for only one wire,bending space shall be permitted to be reduced by the following number of millimeters(inches): a 12.7 mm (1/in.) n 25.4 mm (1 in.) 38.1 mm (1 t/in.) d 50.8 mm (2 in.) 76.2 mm(3 in.) 3. This column shall be permitted to determine the required wire-bending space for compact stranded aluminum conductors in sizes up to 1000 kemil and manufactured using AA-8000 series electrical grade aluminum alloy conductor material in accordance with 310.14. 70-166 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 314—OUTLET, DEVICE,PULL,AND JUNCTION BOXES;CONDUIT BODIES, FITTINGS; AND HANDHOLES 314.3 ample strength and rigidity. If constructed of sheet steel, the (D) Wiring Space— Enclosure. Side-wiring spaces, side metal thickness shall not be less than 1.35 mm (0.053 in.) gutters,or side-wiring compartments of cabinets and cutout uncoated. boxes shall be made tight enclosures by means of covers, barriers, or partitions extending from the bases of the de- (C) Nonmetallic Cabinets, Nonmetallic cabinets shall be vices contained in the cabinet, to the door, frame, or sides listed, or they shall be submitted for approval prior to in- of the cabinet. stallation. Exception: Side-wiring .spaces, side gutters, and side- 312.11 Spacing. The spacing within cabinets and cutout wiring compartments of cabinets shall not be required to be boxes shall comply with 312.11(A) through (D). made tight enclosures where those side spaces contain only conductors that enter the cabinet directly opposite to the (A) General. Spacing within cabinets and cutout boxes devices where they terminate. shall be sufficient to provide ample room for the distribu- tion of wires and cables placed in them and for a separation Partially enclosed back-wiring spaces shall be provided between metal parts of devices and apparatus mounted with covers to complete the enclosure. Wiring spaces that within them in accordance with (A)(1), (A)(2), and (A)(3). are required by 312.11(C) and are exposed when doors are open shall be provided with covers to complete the enclo- (1) Base. Other than at points of support, there shall be an sure. Where adequate space is provided for feed-through airspace of at least 1.59 mm (0.0625 in.) between the base conductors and for splices as required in 312.8, additional of the device and the wall of any metal cabinet or cutout barriers shall not be required. box in which the device is mounted. (2) Doors. There shall be an airspace of at least 25.4 mm (1.00 in.) between any live metal part, including live metal parts of enclosed fuses, and the door. ARTICLE 314 Exception: Where the door is lined with an approved insu- Outlet, Device, Pull, and Junction Boxes; lating material or is of a thickness of metal not less than Conduit Bodies; Fittings; 2.36 nun (0.093 in.) uncoated, the airspace shall not be less and Handhole Enclosures than 12.7 rant (0.500 in.). (3) Live Parts. There shall be an airspace of at least I. Scope and General 12.7 mm (0.500 in.) between the walls, back, gutter parti- 314.1 Scope.This article covers the installation and use of tion, if of metal, or door of any cabinet or cutout box and all boxes and conduit bodies used as outlet, device, junc- the nearest exposed current-carrying part of devices tion, or pull boxes, depending on their use, and handhoie mounted within the cabinet where the voltage does not enclosures. Cast, sheet metal, nonmetallic, and other boxes exceed 250. This spacing shall he increased to at least such as FS, FD, and larger boxes are not classified as con- 25.4 mm (1,00 in.) for voltages of 251 to 600, nominal. duit bodies. This article also includes installation require- Exception: Where the conditions in 312.11(A)(2), E.xcep- meats for fittings used to join raceways and to connect tion, are met, the airspace for nominal voltages from 251 to raceways and cables to boxes and conduit bodies. 600 shall be permitted to be not less than 12.7 mm (0.500 in.). 314.2 Round Boxes. Round boxes shall not be used where conduits or connectors requiring the use of locknuts or (B) Switch Clearance. Cabinets and cutout boxes shall be bushings are to be connected to the side of the box. deep enough to allow the closing of the doors when 30- ampere branch-circuit panelboard switches are in any posi- 314.3 Nonmetallic Boxes. Nonmetallic boxes shall be lion,when combination cutout switches are in any position, permitted only with open wiring on insulators, concealed or when other single-throw switches are opened as far as knob-and-tube wiring, cabled wiring methods with en- their construction permits. tirely nonmetallic sheaths, flexible cords, and nonmetal- (C) Wiring Space. Cabinets and cutout boxes that contain lic raceways. devices or apparatus connected within the cabinet or box to Exception No. 1: Where internal bonding means are pro- more than eight conductors, including those of branch circuits, vided between all entries, nonmetallic boxes shall be per- meter loops, feeder circuits, power circuits, and similar cir- mitted to be used with metal raceways or metal-armored cuits, but not including the supply circuit or a continuation cables. thereof, shall have back-wiring spaces or one or more side- Exception No. 2: Where integral bonding means with a wiring spaces, side gutters, or wiring compartments. provision for attaching an equipment bonding jumper in- 2008 Edition NATIONAL ELECTRICAL CODE 70-167 314.4 ARTICLE 314—OUI LET,DEVICE.PULL,AND JUNCTION BOXES;CONDUIT BODIES; FITTINGS;AND HANDHOLES side the box are provided between all threaded entries in (2) Other Boxes. Boxes 1650 cm-' (100 in.3) or less, other nonmetallic boxes listed for the purpose, nonmetallic boxes than those described in Table 314.16(A), and nonmetallic shall be permitted to be used with metal raceways or metal- boxes shall be durably and legibly marked by the manufac- armored cables. turer with their volume. Boxes described in Table 314.16(A) that have a volume larger than is designated in 314.4 Metal Boxes. Metal boxes shall be grounded and the table shall be permitted to have their volume marked as bonded in accordance with Parts 1,IV,V,VI,VII, and X of required by this section. Article 250 as applicable,except as permitted in 250.112(1). (B) Box Fill Calculations. The volumes in paragraphs 314.5 Short-Radius Conduit Bodies.Conduit bodies such 314.16(8)(1) through (13)(5), as applicable, shall be added as capped elbows and service-entrance elbows that enclose together. No allowance shall be required for small fittings conductors 6 AWG or smaller, and are only intended to such as locknuts and bushings. enable the installation of the raceway and the contained (1) Conductor Fill.Each conductor that originates outside conductors, shall not contain splices, taps, or devices and the box and terminates or is spliced within the box shall be shall be of sufficient size to provide free space for all con- counted once, and each conductor that passes through the ductors enclosed in the conduit body. box without splice or termination shall be counted once. Each loop or coil of unbroken conductor not less than twice II. Installation the minimum length required for free conductors in 300.14 shall be counted twice. The conductor fill shall be calcu- 314.15 Damp or Wet Locations. In damp or wet loca- lated using Table 314.16(B).A conductor, no part of which tions, boxes, conduit bodies, and fittings shall be placed or leaves the box, shall not be counted. equipped so as to prevent moisture from entering or accu- Exception: An equipment grounding conductor or conduc- mulating within the box, conduit body, or fitting. Boxes, tors or not over four fixture wires smaller than 14 AWG, or conduit bodies, and fittings installed in wet locations shall both, shall be permitted to be omitted from the calculations be listed for use in wet locations. where they enter a box from a domed luminaire or similar FPN No. 1: For boxes in floors, see 314.27(C). canopy and terminate within that box. FPN No. 2: For protection against corr osion, see 300.6. (2) Clamp Fill. Where one or more internal cable clamps, whether factory or field supplied, are present in the box, a 314.16 Number of Conductors in Outlet, Device, and single volume allowance in accordance with Table 314.16(B) Junction Boxes, and Conduit Bodies. Boxes and conduit shall be made based on the largest conductor present in the bodies shall be of sufficient size to provide free space for box.No allowance shall be required for a cable connector with all enclosed conductors. In no case shall the volume of the its clamping mechanism outside the box. box, as calculated in 314.16(A), be less than the fill calcu- lation as calculated in 314.16(B).The minimum volume for (3) Support Fittings Fill. Where one or more luminaire conduit bodies shall be as calculated in 314.16(C). studs or hickeys are present in the box, a single volume allowance in accordance with Table 314.16(8) shall be The provisions of this section shall not apply to fermi- nal housings supplied with motors or generators. made for each type of fitting based on the largest conductor present in the box. FPN: For volume requirements of motor or generator ter- minal housings, see 430.12. (4) Device or Equipment Fill.For each yoke or strap con- taining one or more devices or equipment, a double volume Boxes and conduit bodies enclosing conductors 4 AWG allowance in accordance with Table 314.16(B) shall be or larger shall also comply with the provisions of 314.28. made for each yoke or strap based on the largest conductor connected to a device(s) or equipment supported by that (A) Box Volume Calculations. The volume of a wiring yoke or strap. A device or utilization equipment wider than enclosure (box) shalt be the total volume of the assembled a single 50 mm (2 in.) device box as described in Table sections and, where used, the space provided by plaster 314.16(A) shall have double volume allowances provided rings, domed covers, extension rings, and so forth, that are for each gang required for mounting. marked with their volume or are made from boxes the di- mensions of which are listed in Table 314.16(A). (5) Equipment Grounding Conductor Fill. Where one or more equipment grounding conductors or equipment (1) Standard Boxes. The volumes of standard boxes that bonding jumpers enter a box, a single volume allowance are not marked with their volume shall be as given in Table in accordance with Table 314.16(B) shall be made based 314.16(A). on the largest equipment grounding conductor or equip- 70-168 NATIONAL ELEMICAL CODE 2008 Edition ARTICLE 314-OUTLET, DEVICE,PULL,AND JUNCTION BOXES;CONDUIT BODIES; FITTINGS;AND HANDHOLES 314.17 Table 314.16(A) Metal Boxes Minimum Maximum Number of Conductors* Box Trade Size Volume (arranged by AWG Size) mm in. cm` in.-3 18 16 14 12 10 8 6 100 x 32 (4 x 11/4) roundhxaagonal 205 12.5 8 7 6 5 5 5 2 100 x 38 (4 x 1112) round/octagonal 254 15.5 10 8 7 6 6 5 3 100 x 54 (4 x 21/8) roundloctagonal 353 21.5 14 12 10 9 8 7 4 100 x 32 (4 x 11/4) square 295 19,0 12 10 9 8 7 6 3 100 x 38 (4 x 11/2) square 344 21.0 14 12 10 9 8 7 4 100 x 54 (4 x 21/8) square 497 30.3 20 17 15 13 12 10 6 120 x 32 (411/16 x 11/4) square 418 25.5 17 14 12 11 10 8 5 120 x 38 (411/16 x 11/2) square 484 29.5 19 16 14 13 11 9 5 120 x 54 (411/16 x 21/x) square 689 42.0 28 24 21 18 16 14 8 75 x 50 x 38 (3 x 2 x 11/) device 123 7.5 5 4 3 3 3 2 1 75 x 50 x 50 (3 x 2 x 2) device 164 10.0 6 5 5 4 4 3 2 75 x 50 x 57 (3 x 2 x 21/4) device 172 10.5 7 6 5 4 4 3 2 75 x 50 x 65 (3 x 2 x 21/) device 205 12.5 8 7 6 5 5 4 2 75 x 50 x 70 (3 x 2 x 11/4) device 230 14.0 9 8 7 6 5 4 2 75 x 50 x 90 (3 x 2 x 31/2) device 295 18.0 12 10 9 8 7 6 3 100 x 54 x 38 (4 x 21/x x 11/2) device 169 10.3 6 5 5 4 4 3 2 100 x 54 x 48 (4 x 21/x x 17/0 device 213 13.0 8 7 6 5 5 4 2 100 x 54 x 54 (4 x 21/8 x 21/x) device 238 14.5 9 8 7 6 5 4 2 95 x 50 x 65 (3;/4 x 2 x 21/2) masonry box/gang 230 14,0 9 8 7 6 5 4 2 95 x 50 x 90 (3;/4 x 2 x 31/2) masonry box/gang 344 21,0 14 12 10 9 8 7 4 min. 44.5 depth FS --single cover/gang (1 314) 221 13.5 9 7 6 6 5 4 2 min. 60.3 depth FD--single cover/gang (2;/s) 295 18.0 12 10 9 8 7 6 3 min. 44.5 depth FS - multiple cover/gang (F114) 295 18.0 12 10 9 8 7 6 3 min. 60.3 depth FD- multiple cover/gang (T1/9) 395 24.0 16 13 12 10 9 8 4 *Where no volume allowances are required by 314.16(B)(2)through (B)(5). (C) Conduit Bodies. Table 314.16(B) Volume Allowance Required per Conductor (1) General. Conduit bodies enclosing 6 AWG conductors Free Space Within Box for Each or smaller, other than short-radius conduit bodies as de- Conductor scribed in 314.5, shall have a cross-sectional area not less Size of Conductor (AWG) cm in.-3 g than twice the cross-sectional area of the largest conduit or tubing to which they can be attached. The maximum num- 18 24.6 1.50 ber of conductors permitted shall be the maximum number 16 28.7 1.75 permitted by Table l of Chapter 9 for the conduit or tubing 14 32.8 2.00 to which it is attached. 12 36.9 2.25 10 41.0 2.50 8 49.2 3,00 (2) With Splices, Taps, or Devices. Only those conduit 6 81.9 5.00 bodies that are durably and legibly marked by the manufac- turer with their volume shall be permitted to contain splices, taps, or devices. The maximum number of conduc- ment bonding jumper present in the box.Where an additional tors shall be calculated in accordance with 314.16(B). Con- set of equipment grounding conductors, as permitted by duit bodies shall be supported in a rigid and secure manner. 250.146(D), is present in the box,an additional volume allow- ance shall be made based on the largest equipment grounding 314.17 Conductors Entering Boxes, Conduit Bodies, or conductor in the additional set. Fittings. Conductors entering boxes, conduit bodies, or 2008 Edition NATIONAL ELECTRICAL CODE 70-169 314.19 ARTICLE 314—OUTLET. DEVICE,PULL.AND JUNCTION BOXES;CONDUIT BODIES:FITMNGS:AND HANDHOLFS fittings shall be protected from abrasion and shall comply tible material,boxes employing a flush-type cover or faceplate with 314.17(A) through (D)• shall be installed so that the front edge of the box,plaster ring, extension ring, or listed extender will not be set back of the (A) Openings to Be Closed.Openings through which con- finished surface more than 6 mm (114 in.). duclors enter shall be adequately closed. In walls and ceilings constructed of wood or other com- (B) Metal Boxes and Conduit Bodies.Where metal boxes bustible surface material, boxes, plaster rings, extension or conduit bodies are installed with messenger-supported rings, or listed extenders shall be flush with the finished wiring, open wiring on insulators, or concealed knob-and- surface or project therefrom. tube wiring, conductors shall enter through insulating bush- ings or, in dry locations, through flexible tubing extending 314,21 Repairing Plaster and Drywall or Plasterboard. from the last insulating support to not less than 6 mm (1/4 Plaster, drywall, or plasterboard surfaces that are broken or in.) inside the box and beyond any cable clamps. Except as incomplete around boxes employing a flush-type cover or provided in 300.15(C), the wiring shall be firmly secured to faceplate shall be repaired so there will be no gaps or open the box or conduit body. Where raceway or cable is in- spaces greater than 3 mm (1/s in.) at the edge of the box. stalled with metal boxes or conduit bodies, the raceway or cable shat] be secured to such boxes and conduit bodies. 314.22 Surface Extensions. Surface extensions shall be made by mounting and mechanically securing an extension (C) Nonmetallic Boxes and Conduit Bodies.Nonmetallic ring over the box. Equipment grounding shall be in accor- boxes and conduit bodies shall be suitable for the lowest dance with Part VI of Article 250. temperature-rated conductor entering the box. Where non- Exception: A surface extension slrufl be permitted to be metallic boxes and conduit bodies are used with messenger- made front the cover of u box where the cover is designed supported wiring, open wiring on insulators, or concealed so it is unlikelti to fall off or be removed if its securing knob-and-tube wiring, the conductors shall enter the box means becomes loose. The wiring method shall be flexible through individual hales. Where flexible tubing is used to for a length sufficient to perntit re,noval of the cover and enclose the conductors,the tubing shall extend from the last provide access to the box interior, and arranged so that any insulating support to not less than 6 mm ('/4 in.) inside the grounding continuity is independent of the connection be- box and beyond any cable clamp. Where nonmetallic- tween the box and cover sheathed cable or multiconductor Type OF cable is used, the sheath shall extend not less than 6 mm (1/4 in.) inside 314,23 Supports. Enclosures within the scope of this ar- the box and beyond any cable clamp. In all instances, all ticle shalt be supported in accordance with one or more of permitted wiring methods shall be secured to the boxes. the provisions in 314.23(A) through (H). Exception: Where non,etallic•-sheathed cable or multicon durtor Type OF ruble is used with single gang boxes not (A) Surface Mounting. An enclosure mounted on a build- lurger than a nominal size 57 m,rh x 100 nun (l'/a in, ing or other surface shall be rigidly and securely fastened in x 9 in.) mounted in walls or ceilings, curd where the cable place. if the surface does not provide rigid and secure sup- is fastened within 200,n,n(8 in.)of the box measured along port additional support in accordance with other provisions of this section shall be provided. the sheath and where the sheath extends through a cable knockout not less than b ,nrn (1/a in.), securing the cable to (B) Structural Mounting. An enclosure supported from a the box shall not be required. Multiple cable entries shall structural member of a building or from grade shall be be permitted in a .single cable knockout opening. rigidly supported either directly or by using a metal, poly- (D) Conductors 4 AWG or Larger. Installation shall com- meric, or wood brace. ply with 300.4(G). (1) Nails and Screws. Nails and screws, where used as a FPN: See 110.12(A) for requirements on closing unused fastening means, shall be attached by using brackets on the cable and raceway knockout openings. outside of the enclosure, or they shall pass through the interior within 6 mm (V4 in.) of the back or ends of the enclosure. 314.19 Boxes Enclosing Flush Devices. Boxes used to en- Screws shall not be permitted to pass through the box unless close flush devices shall be of such design that the devices exposed threads in the box are protected using approved will be completely enclosed on back and sides and substan- means to avoid abrasion of conductor insulation. tial support for the devices will be provided. Screws for supporting the box shall not be used in attachment of the (2) Braces. Metal braces shall be protected against corro- device contained therein. sion and formed from metal that is not less than 0.51 mm (0.020 in.) thick uncoated. Wood braces shall have a cross 314.20 In Wall or Ceiling. In walls or ceilings with a sur- section not less than nominal 25 mm x 50 mm (1 in. x 2 in.). face of concrete, tile, gypsum, plaster, or other noncombus- Wood braces in wet locations shall be treated for the 70--170 NATIONAL ELECTRICAL CODF. 2008 Edition ARTICLE 314—OUTLET,DEVICE,PULL,AND JUNCTION BOXES;CONDUIT BODIES; FITTINGS;AND HANDHOLES 314.23 conditions. Polymeric braces shall be identified as being conduit shall be secured within 450 mm (18 in.) of the suitable for the use, enclosure. (C) Mounting in Finished Surfaces. An enclosure Exception No. 1: Rigid metal or intermediate metal con- mounted in a finished surface shall be rigidly secured duit shall be permitted to .support a conduit body of an thereto by clamps, anchors, or fittings identified for the size, including a conduit body constructed with only one application. conduit entry;provided the trade size of the conduit body is not larger than the largest trade size of the conduit. (D) Suspended Ceilings. An enclosure mounted to struc- Exception No. 2: An unbroken lengths) of rigid or inter- not more than 1650 cm (I00 in.")or supporting elements of a suspended ceiling shall be mediate metal conduit shall be permitted to support a box ) in size and shall be used for luminaire or lampholder support, or to support a securely fastened in place in accordance with either(D)(l) wiring enclosure that is cut integral part of a luminaire and or (D)(2). used in lieu of a box in accordance with 300.15(B), where (1) Framing Members. An enclosure shall be fastened to all of the following conditions are met: the framing members by mechanical means such as bolts, (a) The conduit is securely fastened at a point so that screws, or rivets, or by the use of clips or other securing the length of conduit beyond the last point of conduit sup- means identified for use with the type of ceiling framing port does not exceed 900 mm (3 ft). member(s) and enclosure(s) employed. The framing mem- (b) The unbroken conduit length before the last point bets shall be adequately supported and securely fastened to of conduit support is 300 mnt (12 in.) or greater, and that each other and to the building structure. portion of the conduit is securely fastened at some point not (2) Support Wires. The installation shall comply with the less than 300 mm (12 in.)front its last point of support. provisions of 300.11(A). The enclosure shall be secured, (c) Where accessible to unqualified persons, the lumi- using methods identified for the purpose, to ceiling support naire or lampholder, measured to its lowest point, is at least wire(s), including any additional support wire(s) installed 2.5 in (8 ft) above grade or standing area and at least for that purpose. Support wire(s)used for enclosure support 900 mm (3 ft) measured horizontally to the 2.5 m (8 ft) shall be fastened at each end so as to be taut within the elevation from windows, doors, porches, fire escapes, or ceiling cavity. similar locations. (d) A luminaire supported by a single conduit does not (E) Raceway Supported Enclosure, Without Devices, exceed 300 nun (12 in.) in any direction from the point of Luminaires, or Lampholders. An enclosure that does not conduit entry. contain a device(s) other than splicing devices or support a (e) The weight supported by any single conduit does luminaire(s), lampholder, or other equipment and is sup- not exceed 9 kg (20 lb). ported by entering raceways shall not exceed 1650 cm3 Y) At the luminaire or lampholder end, the conduit(s) (100 in.3) in size. It shall have threaded entries or have is threaded wrenchtight into the box, conduit body, or inte- hubs identified for the purpose. It shall be supported by two gral wiring enclosure, or into hubs identified for the pur- or more conduits threaded wrenchtight into the enclosure or pose. Where a box or conduit body is used for support, the hubs. Each conduit shall be secured within 900 mm(3 ft)of luminaire shall be secured directly to the box or conduit the enclosure, or within 450 mm (18 in.) of the enclosure if body, or through a threaded conduit nipple not over 75 mm all conduit entries are on the same side. (3 in.) long. Exception: Rigid metal, intermediate metal, or rigid non- (G) Enclosures in Concrete or Masonry. An enclosure metallic conduit or electrical metallic tubing shall be permit- supported by embedment shall be identified as suitably pro- ted to support a conduit body of any size, including a conduit tected from corrosion and securely embedded in concrete or body constructed with only one conduit entry, provided the masonry. trade size of the conduit body is not larger than the largest trade size of the conduit or electrical metallic tubing. (H) Pendant Boxes. An enclosure supported by a pendant shall comply with 314.23(H)(1) or (1-1)(2). (F) Raceway-Supported Enclosures, with Devices, Lu- (1) Flexible Cord. A box shall be supported from a mul- minaires, or Lampholders. An enclosure that contains a ticonductor cord or cable in an approved manner that pro- device(s), other than splicing devices, or supports a lumi- tects the conductors against strain, such as a strain-relief naire(s), lampholder, or other equipment and is supported connector threaded into a box with a hub. by entering raceways shall not exceed 1650 cm (100 in.3) in size. It shall have threaded entries or have hubs identified (2) Conduit.A box supporting lampholders or luminaires, for the purpose, it shall be supported by two or more con- or wiring enclosures within luminaires used in lieu of boxes duits threaded wrenchtight into the enclosure or hubs. Each in accordance with 300.15(B), shall be supported by rigid 2008 Edition NATIONAL ELECTRICAL CODE 70-171 314.24 ARTICLE 314—OUTLET, DEVICE, PULL,AND JUNCTION BOXES;CONDUIT BODIES; FITTINGS;AND HANDHOLES or intermediate metal conduit stems. For stems longer than Gills in.).Where the equipment projects rearward from the 450 mm (18 in.), the stems shall be connected to the wiring mounting plane of the box by more than 25 mm(I in.),the system with flexible fittings suitable for the location.At the box shall have a depth not less than that of the equipment luminaire end, the conduit(s) shall be threaded wrenchtight plus 6 mm (t/4 in.). into the box or wiring enclosure, or into hubs identified for the purpose. (5) Conductors 14AWG and Smaller.Boxes that enclose Where supported by only a single conduit, the threaded equipment supplied by 14 AWG or smaller conductors shall joints shall be prevented from loosening by the use of set- have a depth that is not less than 23.8 mm (15h6 in.). screws or other effective means, or the luminaire, at any Exception to (C)(1) through (C)(S): Utilization equip- point, shall be at least 2.5 m (8 ft) above grade or standing ment that is listed to be installed)with specified boxes shall area and at least 900 mm(3 ft) measured horizontally to the be permitted. 2.5 m (8 ft) elevation from windows, doors, porches, fire escapes, or similar locations. A luminaire supported by a 314.25 Covers and Canopies. In completed installations, single conduit shall not exceed 300 mm (12 in.) in any each box shall have a cover, faceplate, lampholder, or lumi- horizontal direction from the point of conduit entry. naive canopy, except where the installation complies with 410.24(B). 314,24 Minimum Depth of Boxes for Outlets, Devices, (A) Nonmetallic or Metal Covers and Plates. Nonmetal- and utilization Equipment. Outlet and device boxes shall lic or metal covers and plates shall be permitted. Where have sufficient depth to allow equipment installed within metal covers or plates are used, they shall comply with the them to be mounted properly and with sufficient clearance grounding requirements of 250.110. to prevent damage to conductors within the box. FPN: For additional grounding requirements, see 410.42(A) (A) Outlet Boxes Without Enclosed Devices or UtHiza- for metal luminaire canopies, and 404.12 and 406.5(B) for tion Equipment. No box shall have an internal depth of metal faceplates. less than 12.7 mm. (t/a in.). (B) Exposed Combustible Wall or Ceiling Finish.Where (B) Outlet and Device Boxes with Enclosed Devices. a luminaire canopy or pan is used, any combustible wall or Boxes intended to enclose flush devices shall have an in- ceiling finish exposed between the edge of the canopy or ternal depth of not less than 23.8 mm (WO in.), pan and the outlet box shall be covered with noncombus- tible material. (C) Utilization Equipment. Outlet and device boxes that (C) Flexible Cord Pendants. Covers of outlet boxes and enclose utilization equipment shall have a minimum inter- conduit bodies having holes through which flexible cord nal depth that accommodates the rearward projection of the pendants ass shall be provided with bushings designed for equipment and the size of the conductors that supply the p p p g equipment. The internal depth Shall include, where used, the purpose or shall have smooth, well-rounded surfaces on which the cords may bear. So-called hard rubber or corn- that of any extension boxes, plaster rings, or raised covers. position bushings shall not be used. The internal depth shall comply with all applicable provi- sions of(C)(1) through (C)(5). 314.27 Outlet Boxes. (1) Large Equipment. Boxes that enclose utilization (A) Boxes at Luminaire Outlets. Boxes used at luminaire equipment that projects more than 48 mm (17/s in.) rear- or lampholder outlets in a ceiling shall be designed for the ward from the mounting plane of the box shall have a depth purpose and shall be required to support a luminaire weigh- that is not less than the depth of the equipment plus 6 mm ing a minimum of 23 kg(50 lb).Boxes used at luminaire or (y4 in.). lampholder outlets in a wall shall be designed for the pur- pose and shall be marked on the interior of the box to (2) Conductors Larger Than 4 AWG.Boxes that enclose indicate the maximum weight of the luminaire that is per- utilization equipment Supplied by conductors larger than 4 mitted to be supported by the box in the wall, if other than AWG shall be identified for their specific function. 23 kg(SO lb).At every outlet used exclusively for lighting, the box shall be designed or installed so that a luminaire (3) Conductors 8, 6, or 4 AWG. Boxes that enclose utili- may be attached. zation equipment supplied by 8,6,or 4 AWG conductors shall have an internal depth that is not less than 52.4 mm(21116 in.). Exception: A wall-mounted luminaire weighing not more than 3 kg(6 lb)shall be permitted to be supported on other (4) Conductors 12 or 10 AWG. Boxes that enclose utih- boxes or plaster rings that are secured to other Boxes, pro- zation equipment supplied by 12 or 10 AWG conductors tided the luminaire or its supporting yoke is secured to the shall have an internal depth that is not less than 30.2 mm box with no fewer them two No. 6 or larger.screws. 70-172 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 314—OUTLET, DEVICE, PULL,AND JUNCTION BOXES;CONDUIT BODIF-S. FITTINGS;AND HANDHOLES 314.29 (B) Maximum Luminaire Weight. Outlet boxes or fit- (1) Straight Pulls. In straight pulls, the length of the box tings designed for the support of luminaires and installed as shall not be less than eight times the metric designator required by 314.23 shall be permitted to support a lumi- (trade size) of the largest raceway. naire weighing 23 kg (50 lb) or less. A luminaire that weighs more than 23 kg(50 lb)shall be supported indepen- (2) Angle or U Pulls, or Splices. Where splices or where dently of the outlet box unless the outlet box is listed and angle or U pulls are made, the distance between each race- marked for the maximum weight to be supported, way entry inside the box and the opposite wall of the box shall not be less than six times the metric designator (trade (C) Floor Boxes. Boxes listed specifically for this applica- size) of the largest raceway in a row. This distance shall be tion shall be used for receptacles located in the floor. increased for additional entries by the amount of the sum of the diameters of all other raceway entries in the same row Exception: Where the authority having jurisdiction judge s on the same wall of the box. Each row shall be calculated them free from likely exposure to physical damage, mois- individually, and the single row that provides the maximum tore, and dirt, bores located in elevated flours of show distance shall be used. windows and similar locations shall be permitted to be other than those listed for floor applications. Receptacles Exception: Where a raceway or cable entry is in the wall and covers shall be listed as an assembly for this type of of a box or conduit body opposite a removable cover, the location. distance from that wall to the cover shall be pennitted to comply with the distance required for one wire per terminal (D) Boxes at Ceiling-Suspended (Paddle) Fan Outlets. in Table 312.6(A). Outlet boxes or outlet box systems used as the sole support of aceiling-suspended (paddle) fan shall be listed, shall be The distance between raceway entries enclosing the marked by their manufacturer as suitable for this purpose, same conductor shall not be less than six times the metric and shall not support ceiling-suspended (paddle) fans that designator (trade size} of the larger raceway. weigh more than 32 kg (70 lb). For outlet boxes or outlet When transposing cable size into raceway size in box systems designed to support ceiling-suspended 314.28(A)(1) and (A)(2), the minimum metric designator (paddle) fans that weigh more than 16 kg (35 lb), the re- (Fade size) raceway required for the number and size of quired marking shall include the maximum weight to be conductors in the cable shall be used. supported. (3) Smaller Dimensions. Boxes or conduit bodies of di- (E) Utilization Equipment.Boxes used for the support of mensions less than those required in 314.28(A)(1) and utilization equipment other than ceiling-suspended(paddle) (A)(2) shall be permitted for installations of combinations fans shall meet the requirements of 314.27(A) and (B) for of conductors that are less than the maximum conduit or tubing fill (of conduits or tubing being used) permitted by the support of a luminaire that i5 the same Size and weight. Table 1 of Chapter 9, provided the box or conduit body has Exception: Utilization equipment weighing not more than been listed for, and is permanently marked with, the maxi- 3 kg (6 1b) shall be permitted to be supported on other mum number and maximum size of conductors permitted. boxes or plaster rings that are secured to other boxes,pro- vided the equipment or its supporting yoke is secured to the (B) Conductors in Pull or Junction Boxes. In pull boxes box with no fewer than two No. 6 or larger screws or junction boxes having any dimension over 1.8 m (6 ft), all conductors shall be cabled or racked up in an approved 314.25 Pull and Junction Boxes and Conduit Bodies. manner. Boxes and conduit bodies used as pull or junction boxes shall comply with 314.28(A) through (D). (C) Covers. All pull boxes, junction boxes, and conduit bodies shall be provided with covers compatible with the Exception: Terminal housings supplied with motors shall box or conduit body construction and suitable for the con- comply with the provisions of 430.12. ditions of use. Where used, metal covers shall comply with the grounding requirements of 250.110. (A) Minimum Size. For raceways containing conductors of 4 AWG or larger that are required to be insulated, and for (D) Permanent Barriers. Where permanent barriers are cables containing conductors of 4 AWG or larger, the mini- installed in a box, each section shall be considered as a mum dimensions of pull or junction boxes installed in a separate box. raceway or cable run shall comply with (A)(1) through (A)(3). Where an enclosure dimension is to be calculated 314.29 Boxes, Conduit Bodies, and Handhole Enclo- based on the diameter of entering raceways, the diameter sures to Be Accessible. Boxes, conduit bodies, and hand- shall be the metric designator (trade size) expressed in the hole enclosures shall be installed so that the wiring con- units of measurement employed. tained in them can be rendered accessible without removing 2008 Edition NATIONAL ELECTRICAL CODE 70--.173 314.30 ARTICLE 314—OUTLET, DEVICE,PULL.AND JUNCTION BOXES:CONDUIT BODIES: t^I9TINGS:AND HANDHOLES any part of the building or, in underground circuits, without (B) Thickness of Metal. Sheet steel boxes not over excavating sidewalks, paving, earth, or other substance that 1650 cm3 (100 in.-3) in size shall be made from steel not is to be used to establish the finished grade. less than 1.59 rnm (0.0625 in.) thick. The wall of a mal- leable iron box or conduit body and a die-cast or $xc•cptinn: Listed bares and handhole enclosures shall be permanent-mold cast aluminum, brass, bronze, or zinc box Permitted where covered br gravel, light aggregate, or non- or conduit body shall not be less than 2.38 mm (1/32 in,} cohesive granulated soil r'f'their location is effectively iden- thick. Other cast metal boxes or conduit bodies shall have a tiJied and accessible for excavation. thick. thickness not less than 3.17 mm (I/x in.). 314.30 Handhole Enclosures. Handhole enclosures shall Exception No. 1: Listed boxes and conduit bodies shown be designed and installed to withstand all loads likely to be to have equivalent strength and characteristics shall be imposed on them.They shall be identified for use in under- permitted to be made of thinner or other metals. ground systems. Exception No. 2: The walls of listed short radius conduit FPN: See ANSI/SCTE 77-2002, Specification for Under- bodies, as covered in 314.5, shall be permitted to be insde ,ground Enclosure Integrity, for additional information on of thinner metal. deliberate and nondeliberate traffic loading that can be ex- pected to bear on underground enclosures. (C) Metal Boxes Over 1650 cm; (100 in.i). Metal boxes over 1650 cm (100 in.;) in size shall be constructed so as (A) Size. Handhole enclosures shall be sized in accordance to be of ample strength and rigidity. If of sheet steel, the with 314.28(A) for conductors operating at 600 volts or metal thickness shall not be less than 1.35 min (0.053 in.) below, and in accordance with 314.71 for conductors oper- uncoated. ating at over 600 volts. For handhole enclosures without bottoms where the provisions of 314.28(A)(2), Exception, (D) Grounding Provisions. A means shall be provided in or 314.71(B)(1), Exception No. I, apply, the measurement each metal box for the connection of an equipment ground- to the removable cover shall be taken from the end of the ing conductor.The means shall be permitted to be a tapped conduit or cable assembly, hole or equivalent. (B) Wiring Entries. Underground raceways and cable as- 314.41 Covers. Metal covers shall be of the same material semblies entering a handhole enclosure shall extend into as the box or conduit body with which they are used, or the enclosure, but they shall not be required to be mechani- they shall be lined with firmly attached insulating material tally connected to the enclosure. that is not Iess than 0.79 mm(1/32 in.) thick, or they shall be listed for the purpose. Metal covers shall be the same thick- (C) Enclosed Wiring. All enclosed conductors and any ness as the boxes or conduit body for which they are used, splices or terminations, if present, shall be listed as suitable or they shall be listed for the purpose. Covers of porcelain for wet locations. or other approved insulating materials shall be permitted if (D) Covers.Handhole enclosure covers shall have an iden- of such form and thickness as to afford the required protec- tifying mark or logo that prominently identifies the function tion and strength. Of the enclosure, such as "electric." Handhole enclosure 314.42 Bushings. Covers of outlet boxes and conduit bod- covers shall require the use of tools to open, or they shall ies having holes through which flexible cord pendants may weigh over 45 kg (100 lb). Metal covers and other exposed pass shall be provided with approved bushings or shall conductive surfaces shall be bonded in accordance with have smooth, well-rounded surfaces on which the cord may 250.92(A) if the conductors in the handhole are service bear. Where individual conductors pass through a metal conductors,or in accordance with 250.96(A)if the conduc- cover, a separate hole equipped with a bushing of suitable tors in the handhole are feeder or branch-Circuit Conductors. insulating material shall be provided for each conductor. Such separate holes shall be connected by a slot as required III. Construction Specifications by 300.20. 314.40 Metal Boxes, Conduit Bodies, and Fittings. 314.43 Nonmetallic Boxes. Provisions for supports or (A) Corrosion Resistant. Metal boxes, conduit bodies, other mounting means for nonmetallic boxes shall be out- and fittings shall be corrosion resistant or shall be well- side of the box, or the box shall be constructed so as to galvanized, enameled, or otherwise properly coated inside prevent contact between the conductors in the box and the and out to prevent corrosion. supporting screws. FPN: See 300,6 for limitation in the use of boxes and fit- 314.44 Marking. All boxes and conduit bodies, covers, tings protected from corrosion solely by enamel• extension rings, plaster rings, and the like shall be durably 70-174 NATIONAL ELECTRICAL CODE 200M Edition ARTICLE 320—ARMORED CABLE:TYPE AC 320.10 and legibly marked with the manufacturer's name or trade- (C) Removable Sides. One or more sides of any pull box mark. shall be removable. IV. Pull and Junction Boxes for Use on Systems over 314.72 Construction and Installation Requirements. 600 Volts, Nominal (A) Corrosion Protection. Boxes shall be made of mate- rial inherently resistant to corrosion or shall be suitably 314.70 General. Where pull and junction boxes are used protected, both internally and externally, by enameling,gal- on systems over 600 volts, the installation shall comply vanizing, plating, or other means. with the provisions of Part IV and also with the following general provisions of this article: (B) Passing Through Partitions. Suitable bushings, (1) Part 1, 314.2, 314.3, and 314.4 shields, or fittings having smooth, rounded edges shall be (2) Part TI, 314.15; 314.17; 314.20; 314.23(A), (B), or(G); provided where conductors or cables pass through parti- 314.28(B); and 314.29 tions and at other locations where necessary. (3) Part 111, 314.40(A) and (C) and 314.41 (C) Complete Enclosure. Boxes shall provide a complete 314.71 Size of Pull and Junction Boxes.Pull and junction enclosure for the contained conductors or cables. boxes shall provide adequate space and dimensions for the (D) Wiring Is Accessible. Boxes shall be installed so that installation of conductors, and they shall comply with the the wiring is accessible without removing any part of the specific requirements of this section, building, Working space shall be provided in accordance Exception: Terminal housings supplied with motors shall with 110.34. comply with the provisions of 430.12. (E) Suitable Covers. Boxes shall be closed by suitable (A) For Straight Pulls. The length of the box shall not be covers securely fastened in place. Underground box covers that weigh over 45 kg {100 lb) shall be considered meeting less than 48 times the outside diameter, over sheath, of the largest shielded or lead-covered conductor or cable entering this requirement. Covers for boxes shall be permanently the box.The length shall not be less than 32 times the outside marked "DANGER — HIGH VOLTAGE— KEEP OUT." diameter of the largest nonshielded conductor or cable. The marking shall be on the outside of the box cover and shall be readily visible. Letters shall be block type and at (B) For Angle or U Pulls. least 13 mm ('/z in.) in height. (1) Distance to Opposite Wall.The distance between each (F) Suitable for Expected Handling. Boxes and their cable or conductor entry inside the box and the opposite covers shall be capable of withstanding the handling to wall of the box shall not be less than 36 times the outside which they are likely to be subjected. diameter, over sheath, of the largest cable or conductor. This distance shall be increased for additional entries by the amount of the sum of the outside diameters, over sheath, of all other cables or conductor entries through the same wall of the box. ARTICLE 320 Exception No. 1: Where a conductor or cable entry is in Armored Cable' Type AC the wall of a box opposite a removable cover, the distance front that wall to the cover shall be permitted to be not less than the bending radius for the conductors as provided in 1. General 300.34. 320.1 Scope. This article covers the use, installation, and Exception No. 2: Where cables are nonshielded and not construction specifications for armored cable, Type AC. lead covered, the distance of 36 times the outside diameter shall be permitted to be reduced to 24 times the outside 320.2 Definition. diameter. Armored Cable,Type AC. A fabricated assembly of insu- (2) Distance Between Entry and Exit. The distance be- lated conductors in a flexible metallic enclosure. See tween a cable or conductor entry and its exit from the box 320.100. shall not be less than 36 times the outside diameter, over sheath, of that cable or conductor. II. Installation Exception: Where cables are nonshielded and not lead covered, the distance of 36 times the outside diameter shall 320.10 Uses Permitted. Type AC cable shall be permitted be permuted to be reduced to 24 times the outside diameter as follows: 2008 Edition NATIONAL ELECTRICAL CODE 70-175 320.12 ARTICLE 320—ARMORED CABLE:TYPE AC (1) For feeders and branch circuits in both exposed and 320.24 Bending Radius. Bends in Type AC cable shall be concealed work made such that the cable is not damaged. The radius of the (2) In cable trays curve of the inner edge of any bend shall not be less than (3) In dry locations five times the diameter of the Type AC cable. (4) Embedded in plaster finish on brick or other masonry. 320.30 Securing and Supporting. except in damp or wet locations (5) To be run or Fished in the air voids of masonry block or (A) General. Type AC cable shall be supported and se- tile walls where such walls are not exposed or subject cured by staples, cable ties, straps, hangers, or similar fit- to excessive moisture or dampness tings, designed and installed so as not to damage the cable. FPN: The "Uses Permitted" is not an all-inclusive list. (B) Securing. Unless otherwise provided, Type AC cable shall be secured within 300 mm (12 in.) of every outlet 320.12 Uses Not Permitted. Type AC cable shall not be box, junction box, cabinet, or fitting and at intervals not used as follows; exceeding 1.4 m(41/2 ft) where installed on or across fram- (1) Where subject to physical damage ing members. (2) In damp or wet locations (C) Supporting. Unless otherwise provided, Type AC (3) In air voids of masonry block or tile walls where such cable shall be supported at intervals not exceeding 1.4 m walls are exposed or subject to excessive moisture or (4'/2 ft). dampness Horizontal runs of Type AC cable installed in wooden (4) Where exposed to corrosive fumes or vapors or metal framing members or similar supporting means (5) Embedded in plaster Finish on brick or other masonry shall be considered supported where such support does not in damp or wet locations exceed 1.4-m (4'/2-ft) intervals. 320.15 Exposed Work. Exposed runs of cable, except as (D) Unsupported Cables. Type AC cable shall be permit- ted to be unsupported where the cable complies with any of provided in 300.11(A), shall closely follow the surface of the following: the building finish or of running boards. Exposed runs shall also be permitted to be installed on the underside of joists (1) Is fished between access points through concealed where supported at each joist and located so as not to be spaces in finished buildings or structures and support- ing is impracticable subject to physical damage. (2) Is not more than 600 mm (2 ft) in length at terminals 320.17 Through or Parallel to Framing Members. Type where flexibility is necessary AC cable shall be protected in accordance with 300.4(A), (3) Is not more than 1.8 m (6 ft) in length from the last (C), and (D) where installed through or parallel to framing point of cable support to the point of connection to a members. luminaire(s) or other electrical equipment and the cable and point of connection are within an accessible ceil- 320.23 In Accessible Attics. Type AC cables in accessible ing. For the purposes of this section, Type AC cable attics or roof spaces shall be installed as specified in Fittings shall be permitted as a means of cable support. 320.23(A) and (B). 320.40 Boxes and Fittings. At all points where the armor (A) Where Run Across the Top of Floor Joists. Where of AC cable terminates, a fitting shall be provided to protect run across the top of floor joists, or within 2.1 m (7 ft) of wires from abrasion, unless the design of the outlet boxes floor or floor joists across the face of rafters or studding, in or fittings is such as to afford equivalent protection, and, in attics and roof spaces that are accessible, the cable shall be addition, an insulating bushing or its equivalent protection protected by substantial guard strips that are at least as high shall be provided between the conductors and the armor. as the cable. Where this space is not accessible by perma- The connector or clamp by which the Type AC cable is nent stairs or ladders, protection shall only be required fastened to boxes or cabinets shall be of such design that within 1.8 m (6 ft) of the nearest edge of the scuttle hole or the insulating bushing or its equivalent will be visible for attic entrance. inspection. Where change is made from Type AC cable to other cable or raceway wiring methods, a box, fitting, or (B) Cable Installed Parallel to Framing Members. conduit body shalt be installed at junction points as re- Where the cable is installed parallel to the sides of rafters, quired in 300.15. studs,or Hoar joists, neither guard strips nor running boards shall be required, and the installation shall also comply 320.80 Ampacity. The ampacity shall be determined by with 300.4(D). 310.15. 70-176 NATIONAL ELECCRICAL CODE 2008 Edition ARTICLE 322—FLAT CABLE ASSEMBLIES:TYPE FC 322.56 (A) Thermal Insulation. Armored cable installed in ther- (l) As branch circuits to supply suitable tap devices for light- mal insulation shall have conductors rated at 90°C (194°F), ing, small appliances, or small power loads.The rating of The ampacity of cable installed in these applications shall the branch circuit shall not exceed 30 amperes. be that of 60°C (140°F) conductors.The 90°C (194°F) rat- (2) Where installed for exposed work. ing shall be permitted to be used for ampacity derating (3) In locations where they will not be subjected to physical purposes, provided the final derated ampacity does not ex- damage.Where a flat cable assembly is installed less than ceed that for a 6WC (140°F) rated conductor. 2.5 m (8 ft) above the floor or fixed working platform, it (B) Cable Tray.The ampacity of Type AC cable installed in shall be protected by a cover identified for the use. cable tray shall be determined in accordance with 392.11. (4) In surface metal raceways identified for the use. The channel portion of the surface metal raceway systems Ili. Construction Specifications shall be installed as complete systems before the flat cable assemblies are pulled into the raceways. 320.100 Construction.Type AC cable shall have an armor of flexible metal tape and shall have an internal bonding 322.12 Uses Not Permitted. Flat cable assemblies shall strip of copper or aluminum in intimate contact with the not be used as follows: armor for its entire length. (1) Where subject to corrosive vapors unless suitable for 320.104 Conductors. Insulated conductors shall be of a the application type listed in Table 310.13(A) or those identified for use in (2) In hoistways or on elevators or escalators this cable. In addition, the conductors shall have an overall (3) In any hazardous (classified) location moisture-resistant and fire-retardant fibrous covering. For (4) Outdoors or in wet or damp locations unless identified Type ACT, a moisture-resistant fibrous covering shall be for the use required only on the individual conductors. 320.108 Equipment Grounding Conductor. Type AC 322.30 Securing and Supporting. The flat cable assem- blies shall be supported by means of their special design cable shall provide an adequate path for fault Current as features, within the surface metal raceways. required by 250.4(A)(5) or (B)(4) to act as an equipment grounding conductor. The surface metal raceways shall be supported as re- quired for the specific raceway to be installed. 320.120 Marking. The cable shall be marked in accor- dance with 310.11, except that Type AC shall have ready 322.40 Boxes and Fittings. identification of the manufacturer by distinctive external (A) Dead Ends. Each flat cable assembly dead end shall markings on the cable sheath throughout its entire length. be terminated in an end-cap device identified for the use. The dead-end fitting for the enclosing surface metal raceway shall be identified for the use. ARTICLE 322 (B) Luminaire Hangers. Luminaire hangers installed with Flat Cable Assemblies: Type FC the flat cable assemblies shall be identified for the use. (C) Fittings. Fittings to be installed with flat cable assem- 1. General blies shall be designed and installed to prevent physical 322.1 Scope. This article covers the use, installation, and damage to the cable assemblies. construction specifications for flat cable assemblies, Type FC (D) Extensions. All extensions from Hat cable assemblies shall be made by approved wiring methods, within the 322.2 Definition. junction boxes, installed at either end of the flat cable Flat Cable Assembly, Type FC. An assembly of parallel assembly runs. conductors formed integrally with an insulating material 322.56 Splices and Taps. web specifically designed for field installation in surface metal raceway. (A) Splices. Splices shall be made in listed junction boxes. II. Installation (B) Taps. Taps shall be made between any phase conduc- tor and the grounded conductor or any other phase conduc- 322.10 Uses Permitted. Flat cable assemblies shall be per- for by means of devices and fittings identified for the use. mitted only as follows: Tap devices shall be rated at not less than 15 amperes, or 2008 Edition NATIONAL ELECTRICAL CODE 70-177 322.100 ARTICLE 324—FLAT CONDUCTOR CABLE:TYPE FCC more than 300 volts to ground, and shall be color-coded in 324.2 Definitions. accordance with the requirements of 322.120(C). Bottom Shield. A protective layer that is installed between the floor and Type FCC flat conductor cable to protect the III. Construction cable from physical damage and may or may not be incor- 322.100 Construction. Flat cable assemblies shall consist porated as an integral part of the cable. of two, three, four, or five conductors. Cable Connector. A connector designed to join Type FCC cables without using a junction box. 322.104 Conductors. Flat cable assemblies shall have FCC System. A complete wiring system for branch circuits conductors of 10 AWG special stranded copper wires. that is designed for installation under carpet squares. The FCC system includes Type FCC cable and associated 322.112 Insulation.The entire Hat cable assembly shall be shielding, connectors, terminators, adapters, boxes, and re- formed to provide a suitable insulation covering all the ceptacles. conductors and using one of the materials recognized in Table 310.13(A) for general branch-circuit wiring. Insulating End. An insulator designed to electrically insu- late the end of a Type FCC cable. 322.120 Marking. Metal Shield Connections. Means of connection designed (A) Temperature Rating. In addition to the provisions of to electrically and mechanically connect a metal shield to 310.11, Type FC cable shall have the temperature rating another metal shield, to a receptacle housing or self- durably marked on the surface at intervals not exceeding contained device, or to a transition assembly. 600 mint (24 in.). Top Shield.A grounded metal shield covering under-carpet (B) identification of Grounded Conductor. The grounded components of the FCC system for the purposes of provid- conductor shall be identified throughout its length by means of ing protection against physical damage. a distinctive and durable white or gray marking. Transition Assembly. An assembly to facilitate connection o FPN: The color gray may have been used in the past as an f the FCC system to other wiring systems, incorporating ungrounded conductor.Care should be taken when working (1) a means of electrical interconnection and (2) a suitable on existing systems. box or covering for providing electrical safety and protec- tion against physical damage. (C) Terminal Block Identification.Terminal blocks iden- Type FCC Cable. Three or more flat copper conductors tified for the use shall have distinctive and durable mark- placed edge-to-edge and separated and enclosed within an ings for color or word coding. The grounded conductor section shall have a white marking or other suitable desig- nation.The next adjacent section of the terminal block shall 324.6 Listing Requirements.Type FCC cable and associ- have a black marking or other suitable designation. The next section shall have a red marking or other suitable ated fittings shall be listed. designation. The final or outer section, opposite the grounded conductor section of the terminal block, shall H. Installation have a blue marking or other suitable designation. 324,10 Uses Permitted. (A) Branch Circuits. Use of FCC systems shall be permit- ted both for general-purpose and appliance branch circuits ARTICLE 324 and for individual branch circuits. Flat Conductor Cable: Type FCC (B) Branch-Circuit Ratings. (1) Voltage. Voltage between ungrounded conductors shall I. General not exceed 300 volts.Voltage between ungrounded conduc- 324.1 Scope. This article covers afield-installed wiring tors and the grounded conductor shall not exceed 150 volts. system for branch circuits incorporating Type FCC cable (2) Current. General-purpose and appliance branch cir- and associated accessories as defined by the article. The cuits shall have ratings not exceeding 20 amperes. Indi- wiring system is designed for installation under carpet vidual branch circuits shall have ratings not exceeding 30 squares. amperes. 70-178 NATIONAL ELECTRICAL CODE 2WX Edition ARTICLE 324—FLAT CONDUCTOR CABLE:'TYPE FCC 324.56 (C) Floors. Use of FCC systems shall be permitted on ing ends. The top shield shall completely cover all cable hard, sound, smooth, continuous floor surfaces made of runs, corners, connectors, and ends, concrete,ceramic, or composition flooring, wood, and simi- lar materials. (2) Bottom Shield. A bottom shield shall be installed be- neath all Type FCC cable, connectors, and insulating ends. (D) Walls. Use of FCC systems shall be permitted on wall surfaces in surface metal raceways. (D) Connection to Other Systems.Power feed,grounding connection, and shield system connection between the FCC (E) Damp Locations. Use of FCC systems in damp loca- system and other wiring, systems shall be accomplished in a tions shall be permitted. transition assembly identified for this use. (F) Heated Floors. Materials used for floors heated in ex- (E) Metal-Shield Connectors. Metal shields shall be con- cess of 30°C (86°F) shall be identified as suitable for use at nected to each other and to boxes, receptacle housings, these temperatures. self-contained devices, and transition assemblies using (G) System Height. Any portion of an FCC system with a metal-shield connectors. height above floor level exceeding 2.3 mm (0.090 in.) shall be tapered or feathered at the edges to floor level. 324.41 Floor Coverings. Floor-mounted Type FCC cable, cable connectors, and insulating ends shall be covered with • 324.12 Uses Not Permitted. FCC systems shall not be carpet squares not larger than 914 mm (36 in.) square. used in the following locations: Carpet squares that are adhered to the floor shall be at- (I) Outdoors or in wet locations tached with release-type adhesives. (2) Where subject to corrosive vapors 324.42 Devices. (3) In any hazardous (classified) location (4) In residential, school, and hospital buildings (A) Receptacles. All receptacles, receptacle housings, and self-contained devices used with the FCC system shall be 324.18 Crossings. Crossings of more than two Type FCC identified for this use and shall be connected to the Type cable runs shall not be permitted at any one point. Cross- FCC cable and metal shields, Connection from any ground- ings of a Type FCC cable over or under a flat communica- ing conductor of the Type FCC cable shall be made to the tions or signal cable shall be permitted. In each case, a shield system at each receptacle. grounded layer of metal shielding shall separate the two cables, and crossings of more than two flak cables shall not (B) Receptacles and Housings. Receptacle housings and be permitted at any one point. self-contained devices designed either for floor mounting or for in-wall or on-wall mounting shall be permitted for use 324.30 Securing and Supporting. All FCC system com- with the FCC system. Receptacle housings and self ponents shall be firmly anchored to the floor or wall using contained devices shall incorporate means for facilitating an adhesive or mechanical anchoring system identified for entry and termination of Type FCC cable and for electri- this use. Floors shall be prepared to ensure adherence of the cally connecting the housing or device with the metal FCC system to the floor until the carpet squares are placed. shield.Receptacles and self-contained devices shall comply with 406.3. Power and communications outlets installed 324.40 Boxes and Fittings. together in common housing shall be permitted in accor- (A) Cable Connections and Insulating Ends. All Type dance with 800.133(A)(1)(c), Exception No. 2. FCC cable connections shall use connectors identified for 324.56 Splices and Taps. their use, installed such that electrical continuity, insulation, and sealing against dampness and liquid spillage are provided. (A) FCC Systems Alterations. Alterations to FCC sys- All bare cable ends shall be insulated and sealed against tems shall be permitted. New cable connectors shall be dampness and liquid spillage using listed insulating ends. used at new connection points to make alterations. It shall (B) Polarization of Connections. All receptacles and con- be permitted to leave unused cable runs and associated nections shall be constructed and installed so as to maintain cable connectors in place and energized. All cable ends proper polarization of the system, shall be covered with insulating ends. (C) Shields. (B) Transition Assemblies. All transition assemblies shall be identified for their use. Each assembly shall incorporate (1) Top Shield. A metal top shield shall be installed over means for facilitating entry of the Type FCC cable into the all floor-mounted Type FCC cable, connectors, and insulat- assembly, for connecting the Type FCC cable to grounded 2008 Edition NATIONAL ELECTRICAL CODE 70-179 324.60 ARTICLE 326—INTEGRATED GAS SPACER CABLE:TYPE IGS conductors,and for electrically connecting the assembly to the metal cable shields and to equipment grounding conductors. ARTICLE 326 324.60 Grounding. All metal shields, boxes, receptacle Integrated Gas Spacer Cable: Type IGS housings, and self-contained devices shall be electrically continuous to the equipment grounding conductor of the 1. General supplying branch circuit. All such electrical connections 326.1 Scope. This article covers the use, installation, and shall be made with connectors identified for this use. The electrical resistivity of such shield system shall not be more construction specifications for integrated gas spacer cable, than that of one conductor of the Type FCC cable used in Type IGS. the installation. 326.2 Definition. Ill. Construction Integrated Gas Spacer Cable,Type IGS.A factory assem- bly of one or more conductors,each individually insulated and 324.100 Construction. enclosed in a loose fit, nonmetallic flexible conduit as an in- (A) Type FCC Cable. Type FCC cable shall be listed for tegrated gas spacer cable rated 0 through 600 volts. use with the FCC system and shall consist of three, four, or five flat copper conductors, one of which shall be an equip- II. Installation went grounding conductor. 326.10 Uses Permitted.Type IGS cable shall be permitted (B) Shields. for use under ground,including direct burial in the earth, as the following: (1) Materials and Dimensions.All top and bottom shields (1) Service-entrance conductors shall be of designs and materials identified for their use. (2) Feeder or branch-circuit conductors Top shields shall be metal. Both metallic and nonmetallic materials shall be permitted for bottom shields. 326.12 Uses Not Permitted. Type IGS cable shall not be (2) Resistivity. Metal shields shall have cross-sectional ar- used as interior wiring or be exposed in contact with buildings. eas that provide for electrical resistivity of not more than that of one conductor of the Type FCC cable used in the 326.24 Bending Radices. Where the coilable nonmetallic installation. conduit and cable is bent for installation purposes or is flexed or bent during shipment or installation, the radii of 324.101 Corrosion Resistance. Metal components of the bends measured to the inside of the bend shall not be less system shall be either corrosion resistant, coated with than specified in Table 326.24. corrosion-resistant materials, or insulated from contact with Table 326.24 Minimum Radii of Bends corrosive substances. 324.112 Insulation. The insulating material of the cable Conduit Size Minimum Radii shall be moisture resistant and flame retardant. All insulat- Metric Designator Trade Size mm in. ing materials in the FCC systems shall be identified for their use. 53 2 600 24 78 3 900 35 324.120 Markings. 103 4 1150 45 (A) Cable Marking. Type FCC cable shall be clearly and 326.26 Bends. A run of Type IGS cable between pull durably marked on both sides at intervals of not more than boxes or terminations shall not contain more than the 610 mm (24 in.) with the information required by equivalent of four quarter bends(360 degrees total),includ- 310.11(A) and with the following additional information: ing those bends located immediately at the pull box or (1) Material of conductors terminations. (2) Maximum temperature rating (3) Ampacity 326.40 Fittings. Terminations and splices for Type IGS cable shall be identified as a type that is suitable for main- (B) Conductor Identification.Conductors shall be clearly taining the gas pressure within the conduit.A valve and cap and durably identified on both sides throughout their length shall be provided for each length of the cable and conduit as specified in 310.12, to check the gas pressure or to inject gas into the conduit. 70-180 NATIONAL ELECTRICAL CODE 2006 Edition ARTICLE 328—MEDIUM VOLTAGE CABLE:TYPE M V 328.80 326.80 Ampacity, The ampacity of Type iGS cable shall 326.120 Marking. The cable shall be marked in accor- not exceed the values shown in Table 326.80. dance with 310.11(A), 310.11(13)(1), and 310.11(D). Table 326.80 Ampacity of Type IGS Cable Size (kcmil) Amperes Size (kcmil) Amperes 250 119 2500 376 ARTICLE 328 500 168 3000 412 Medium Voltage Cable: Type MV 750 206 3250 429 1000 238 3500 445 1250 266 3750 461 1. General 1500 292 4000 476 1750 315 4250 491 328.1 Scope. This article covers the use, installation, and 2000 336 4500 505 construction specifications for medium voltage cable, Type 2250 357 4750 519 MV. III. Construction Specifications 328.2 Definition. 326.104 Conductors. The conductors shall be solid alumi- Medium Voltage Cable, Type MV. A single or multicon- num rods, laid parallel,consisting of one to nineteen 12.7 nun ductor solid dielectric insulated cable rated 2001 volts or (1!2 in.) diameter rods. The minimum conductor size shall be higher, 250 kcmil, and the maximum size shall be 4750 kcmil. 326.112 Insulation. The insulation shall be dry kraft paper 11. Installation tapes and a pressurized sulfur hexafluoride gas (SF.), both 328.10 Uses Permitted.Type MV cable shall be permitted approved for electrical use.The nominal gas pressure shall be for use on power systems rated up to 35,000 volts nominal 138 kPa gauge (20 pounds per square inch gauge).The thick- ness of the paper spacer shall be as specified in Table 326.112, as follows: (1) In wet or dry locations Table 326.112 Paper Spacer Thickness (2) In raceways Thickness (3) In cable trays, where identified for the use, in accor- dance with 3913, 392.6(F), 392.8, and 392.12. Size (kcmil) mm in. Exception: Type MV cable that has an overall metallic 250-1000 1.02 0.040 sheath or armor, also complies with the requirements for 1250-4750 1.52 0.060 Type MC cable, and is identified as "MV or MC"shall be permitted to be installed in cable trays in accordance with 326.116 Conduit. The conduit shall be a medium density 392.3(B)(2). polyethylene identified as suitable for use with natural gas (4) Direct buried in accordance with 300.50 rated pipe in metric designator 53, 78, or 103 (trade size 2, (5) In messenger-supported wiring in accordance with Part 3, or 4). The percent fill dimensions for the conduit are It of Article 396 shown in Table 326.116. The size of the conduit permitted for each conductor (6) As exposed runs in accordance with 300.37 size shall be calculated for a percent fill not to exceed those Exception: Type MV cable that has an overall metallic found in Table 1, Chapter 9. sheath or armor, also complies with the requirements for Type MC cable, and is identified as WV or MC"shall be Table 326.II6 Conduit Dimensions permitted to be installed as exposed runs of metal-clad Actual cable in accordance with 300.37 Outside Actual Inside FPN: The "Uses Permitted" is not an all-inclusive list. Conduit Size Diameter Diameter Metric Trade 328.12 Uses Not Permitted. Type MV cable shall not be Designator Size mm in. mm in. used where exposed to direct sunlight, unless identified for the use. 53 2 60 2.375 49.46 1.947 78 3 89 3.500 73.30 2.886 328.80 Ampacity. The ampacity of Type MV cable shall 103 4 114 4.500 94.23 3.710 be determined in accordance with 310.60. The ampacity of 2008 Edition NATIONAL ELEC-rRICAL CODE 70.181 328.100 ARTICLE 330—METAL-CLAD CABLE:TYPE MC Type MV cable installed in cable tray shall be determined c. The insulated conductors under the metallic cover- in accordance with 392.13. ing are listed for use in wet locations and a corrosion-resistant jacket is provided over the me- IIl. Construction Specifications tallic sheath. (12) Where single-conductor cables are used, all phase 328.100 Construction.Type MV cables shall have copper, conductors and, where used, the neutral conductor aluminum, or copper-clad aluminum conductors and shall shall be grouped together to minimize induced voltage comply with Table 310.13(C)and Table 310.13(D)or Table on the sheath. 310.13(E). (B) Specific Uses.Type MC cable shall be permitted to be 328.120 Marking. Medium voltage cable shall be marked installed in compliance with Parts II and III of Article 725 as required by 310.11. and 770.133 as applicable and in accordance with 330.10(B)(1) through (13)(4). (1) Cable Tray.Type MC cable installed in cable tray shall comply with 392.3, 392.4, 392.6, and 392.8 through ARTICLE 330 392.13. Metal-Clad Cable: Type MC (2) Direct Buried. Direct-buried cable shall comply with 300.5 or 300.50, as appropriate. 1. General (3) Installed as Service-Entrance Cable. Type MC cable installed as service-entrance cable shall be permitted in ac- 330.1 Scope. This article covers the use, installation, and cordance with 230.43. construction specifications of metal-clad cable, Type MC. (4) Installed Outside of Buildings or Structures or as 330.2 Definition. Aerial Cable.Type MC cable installed outside of buildings or structures or as aerial cable shall comply with 225.10, Metal Clad Cable, Type MC. A factory assembly of one 396.10, and 396.12. or more insulated circuit conductors with or without optical fiber members enclosed in an armor of interlocking metal FPN: The "Uses Permitted" is not an all-inclusive list. tape, or a smooth or corrugated metallic sheath. 330.12 Uses Not Permitted. Type MC cable shall not be used under either of the following conditions: 11. installation (1) Where subject to physical damage 330.10 Uses Permitted. (2) Where exposed to any of the destructive corrosive con- ditions in(a)or(b), unless the metallic sheath or armor (A) General Uses. Type MC cable shall be permitted as is resistant to the conditions or is protected by material follows: resistant to the conditions: (1) For services, feeders, and branch circuits a. Direct buried in the earth or embedded in concrete (2) For power, lighting, control, and signal circuits unless identified for direct burial (3) Indoors or outdoors b. Exposed to cinder fills, strong chlorides, caustic al- (4) Exposed or concealed kalis, or vapors of chlorine or of hydrochloric acids (5) To be direct buried where identified for such use 330.17 Through or Parallel to Framing Members.Type (6) In cable tray where identified for such use MC cable shall be protected in accordance with 300.4(A), (7) In any raceway (C), and (D) where installed through or parallel to framing (8) As aerial cable on a messenger members. (9) In hazardous (classified) locations as permitted (10) In dry locations and embedded in plaster finish on brick 330.23 in Accessible Attics. The installation of Type MC or other masonry except in damp or wet locations cable in accessible attics or roof spaces shall also comply with 320.23. (11) In wet locations where any of the following condi- tions are met: 330.24 Bending Radius. Bends in Type MC cable shall be a. The metallic covering is impervious to moisture. so made that the cable will not be damaged. The radius of b. A lead sheath or moisture-impervious jacket is pro- the curve of the inner edge of any bend shall not be less vided under the metal covering. than required in 330.24(A) through (C). 70-182 NATIONAL ELECTRICAL.CODE 2008 Edition ARTICLE 330—METAL-CLAM CABLE:TYPE MC 330.116 (A) Smooth Sheath. 330.40 Boxes and Fittings. Fittings used for connecting (1) Ten times the external diameter of the metallic sheath Type MC cable to boxes, cabinets, or other equipment shall for cable not more than 19 mm (a/a in.) in external be listed and identified for such use. diameter (2) Twelve times the external diameter of the metallic 330.80 Ampacity.The ampacity of Type MC cable shall be sheath for cable more than 19 mm (1/4 in.) but not more determined in accordance with 310.15 or 310.60 for 14 AWG than 38 mm (11/2 in.) in external diameter and larger conductors and in accordance with Table 402.5 for (3) Fifteen times the external diameter of the metallic 18 AWG and 16 AWG conductors. The installation shall not exceed the temperature s equipment. ratio of terminations and a ui sheath for cable more than 38 mm {I t/z in.) in external g' q p diameter (A) Type MC Cable Installed in Cable Tray. The am- pacities for Type MC cable installed in cable tray shall be (B) Interlocked-Type Armor or Corrugated Sheath. determined in accordance with 342.11 and 392.13. Seven times the external diameter of the metallic sheath. (B) Single Type MC Conductors Grouped Together. (C) Shielded Conductors.Twelve times the overall diam- Where single Type MC conductors are grouped together in eter of one of the individual conductors or seven times the a triangular or square configuration and installed on a mes- overall diameter of the multiconductor cable, whichever is senger or exposed with a maintained free airspace of not greater. less than 2.15 times one conductor diameter (2.15 x O.D.) of the largest conductor contained within the configuration 330.30 Securing and Supporting. and adjacent conductor configurations or cables,the ampac- ity of the conductors shall not exceed the allowable am- (A) General. Type MC cable shall be supported and se- pacities in the following tables: cured by staples, cable ties, straps, hangers, or similar fit- (1) Table 310.20 for conductors rated 0 through 2000 volts tings or other approved means designed and installed so as not to damage the cable. (2) Table 310.67 and Table 310.68 for conductors rated over 2000 volts (B) Securing. Unless otherwise provided,cables shall be se- cured at intervals not exceeding 1.8 m (6 ft). Cables contain- 111. Construction Specifications ing four or fewer conductors sized no larger than 10 AWG shall be secured within 300 mm(12 in.)of every box,cabinet, 330.104 Conductors. Conductors shall be of copper, alu- fitting, or other cable termination. minum, copper-clad aluminum, nickel or nickel-coated copper, solid or stranded. The minimum conductor size (C) Supporting. Unless otherwise provided, cables shall shall be 18 AWG copper, nickel or nickel-coated copper, be supported at intervals not exceeding 1.8 m (6 ft). and 12 AWG aluminum or copper-clad aluminum. Horizontal runs of Type MC cable installed in wooden or metal framing members or similar supporting means 330.108 Equipment Grounding Conductor. Where Type shall be considered supported and secured where such sup- MC cable is used to provide an equipment grounding con- port does not exceed 1.8-m (6-ft) intervals. ductor, it shall comply with 250.118(10) and 250.122. (D) Unsupported Cables.Type MC cable shall be permit- 330.112 Insulation. Insulated conductors shall comply ted to be unsupported where the cable: with 330.112(A) or (B). (1) Is fished between access points through concealed (A) 600 Volts. Insulated conductors in sizes 18 AWG and spaces in finished buildings or structures and support- 16 AWG shall be of a type listed in Table 402.3, with a ing is impractical; or maximum operating temperature not less than 90°C (2) Is not more than 1.8 m (6 ft) in length from the last (194°F)and as permitted by 725.49. Conductors larger than point of cable support to the point of connection to 16 AWG shall be of a type listed in Table 310.13(A) or of luminaires or other electrical equipment and the cable a type identified for use in Type MC cable. and point of connection are within an accessible ceil- ing. For the purpose of this section, Type MC cable (B) Over 600 Volts.Insulated conductors shall be of a type fittings shall be permitted as a means of cable support. listed in Table 310.13(C) through Table 310.13(E). 330.31 Single Conductors.Where single-conductor cables 330.116 Sheath. Metallic covering shall be one of the fol- with a nonferrous armor or sheath are used, the installation lowing types: smooth metallic sheath, corrugated metallic shall comply with 300.20. sheath, interlocking metal tape armor. The metallic sheath 2()08 Edition NATIONAL ELECTRICAL CODE 70-183 332.1 ARTICLE 332—MINERAL-INSULATED,METAL-SHEATHED CABLE:TYPE MI shall be continuous and close fitting.A nonmagnetic sheath (1) In underground runs unless protected from physical or armor shall be used on single conductor Type MC. damage, where necessary Supplemental protection of an outer covering of corrosion- (2) Where exposed to conditions that are destructive and resistant material shall be permitted and shall be required corrosive to the metallic sheath, unless additional pro- where such protection is needed. The sheath shall not be tection is provided used as a current-carrying conductor. FPN: See 300.6 for protection against corrosion. 332.17 Through or Parallel to Framing Members. Type MI cable shall be protected in accordance with 300.4 where installed through or parallel to framing members. 332.24 Bending Radius. Bends in Type MI cable shall be ARTICLE 332 so made that the cable will not be damaged. The radius of Mineral-Insulated, Metal-Sheathed the inner edge of any bend shall not be less than required as Cable: Type MI follows: (1) Five times the external diameter of the metallic sheath for cable not more than 19 mm (.114 in.) in external 1. General diameter 332.1 Scope. This article covers the use, installation, and (2) Ten times the external diameter of the metallic sheath construction specifications for mineral-insulated, metal- for cable greater than 19 mm (;/a in.) but not more than sheathed cable, Type MI. 25 MM (I in.) in external diameter 332.2 Definition. 332.30 Securing and Supporting. Type MI cable shall be Mineral-Insulated, Metal-Sheathed Cable, Type MI. A supported and secured by staples, straps,hangers,or similar factory assembly of one or more conductors insulated with fittings, designed and installed so as not to damage the a highly compressed refractory mineral insulation and en- cable, at intervals not exceeding 1.8 to (6 ft). closed in a liquidtight and gastight continuous copper or (A) Horizontal Runs Through Holes and Notches. In alloy steel sheath, other than vertical runs, cables installed in accordance with 300.4 shall be considered supported and secured where I1. Installation such support does not exceed 1.8 m (6 ft) intervals. 332.10 Uses Permitted. Type MI cable shall be permitted (B) Unsupported Cable.Type MI cable shall be permitted as follows: to be unsupported where the cable is fished between access (1) For services, feeders, and branch circuits points through concealed spaces in finished buildings or (2) For power, lighting, control, and signal circuits structures and supporting is impracticable. (3) In dry, wet, or continuously moist locations (C) Cable Trays. All MI cable installed in cable trays (4) Indoors or outdoors shall comply with 392.8(B). (5) Where exposed or concealed (6) Where embedded in plaster, concrete, fill, or other 332.31 Single Conductors.Where single-conductor cables masonry, whether above or below grade are used, all phase conductors and, where used, the neutral (7) In any hazardous (classified) location conductor shall be grouped together to minimize induced (8) Where exposed to oil and gasoline voltage on the sheath. (9) Where exposed to corrosive conditions not deteriorat- 332.40 Boxes and Fittings. ing to its sheath (10) In underground runs where suitably protected against (A) Fittings. Fittings used for connecting Type MI cable to physical damage and corrosive conditions boxes, cabinets, or other equipment shall be identified for (11) In or attached to cable tray such use, FPN: The "Uses Permitted" is not an all-inclusive list. (B) Terminal Seals. Where Type MI cable terminates, an end seal fitting shall be installed immediately after stripping 332.12 Uses Not Permitted. Type MI cable shall not be to prevent the entrance of moisture into the insulation. The used under the following conditions or in the following conductors extending beyond the sheath shall be individu- locations: ally provided with an insulating material. 70--184 NATIONAL ELECTRICAL CODE. 2000 Edition ARTICLE 334—NONMETALLIC-SHEATHED CABLE:TYPES NM,NMC, AND NMS 334,10 332.80 Ampacity.The ampacity of Type MI cable shall be Type NM. Insulated conductors enclosed within an overall determined in accordance with 310.15.The conductor tem- nonmetallic jacket. perature at the end seal fitting shall not exceed the tempera- ture rating of the Iisted end seal fitting, and the installation Type NMC. Insulated conductors enclosed within an over- shall not exceed the temperature ratings of terminations or all, corrosion resistant, nonmetallic jacket. equipment. Type NMS. Insulated power or control conductors with (A) Type MI Cable Installed in Cable Tray.The ampaci- signaling, data, and communications conductors within an ties for Type MI cable installed in cable tray shall be deter- overall nonmetallic jacket. mined in accordance with 392.11. 334.6 Listed. Type NM, Type NMC, and Type NMS (B) Single Type MI Conductors Grouped Together. cables shall be listed. Where single Type MI conductors are grouped together in a triangular or square configuration, as required by 332.31, and installed on a messenger or exposed with a maintained II. Installation free air space of not less than 2.15 times one conductor 334.10 Uses Permitted. Type NM, Type NMC, and Type diameter (2.15 x O.D.) of the largest conductor contained NMS cables shall be permitted to be used in the following: within the configuration and adjacent conductor configura- tions or cables, the ampacity of the conductors shall not {1) One- and two-Family dwellings. exceed the allowable ampacities of Table 310.17. (2) Multifamily dwellings permitted to be of Types Ill, IV, and V construction except as prohibited in 334.12. 111. Construction Specifications (3) Other structures permitted to be of Types III, IV, and V construction except as prohibited in 334.12. Cables 332.104 Conductors. Type MI cable conductors shall be shall be concealed within walls, floors, or ceilings that of solid copper, nickel, or nickel-coated copper with a re- provide a thermal barrier of material that has at least a sistance corresponding to standard AWG and kcmil sizes. 15-minute finish rating as identified in listings of fire- 332.108 Equipment Grounding Conductor. Where the rated assemblies. outer sheath is made of copper, it shall provide an adequate FAN No. 1: Types of building construction and occupancy path to Serve as an equipment grounding conductor.Where classifications are defined in NFPA 220-2006,Standard on the outer sheath i5 made of steel, a separate equipment Types of Building Construction, or the applicable building grounding conductor shall be provided. code, or both. FPN No. 2: See Annex E for determination of building 332.112 Insulation, The conductor insulation in Type MI types [NFPA 220,Table 3-11. cable shall be a highly compressed refractory mineral that (4) Cable trays in structures permitted to be Types 111, IV, provides proper spacing for all conductors. or V where the cables are identified for the use. 332.116 Sheath. The outer sheath shall be of a continuous FPN: See 310.10 for temperature limitation of conductors. construction to provide mechanical protection and moisture seal. (A) Type NM- Type NM cable shall be permitted as follows: (1) For both exposed and concealed work in normally dry locations except as prohibited in 334.10(3) ARTICLE 334 (2) To be installed or fished in air voids in masonry block Nonmetallic-Sheathed Cable: or tile walls Types NM, NMC, and NMS (B) Type NMC. Type NMC cable shall be permitted as follows: I. General (1) For both exposed and concealed work in dry, moist, 334.1 Scope. This article covers the use, installation, and damp, or corrosive locations, except as prohibited by construction specifications of nonmetal]ic-sheathed cable. 334.10(3) (2) In outside and inside walls of masonry block or tile 334.2 Definitions. (3) In a shallow chase in masonry, concrete, or adobe pro- Nonmetallic-Sheathed Cable. A factory assembly of two tected against nails or screws by a steel plate at least or more insulated conductors enclosed within an overall 1.59 mm (IA6 in.) thick and covered with plaster, nonmetallic jacket. adobe, or similar finish 2008 Edition NATIONAL ELECTRICAL CODE 70-185 334.12 ARTICLE 334 NONMETALLIC-SHEATHED CABLE:TYPES NM,NMC.AND NMS (C) Type NMS. Type NMS cable shall be permitted as (B) Protection from Physical Damage. Cable shall be follows: protected from physical damage where necessary by rigid (1) For both exposed and concealed work in normally dry metal conduit, intermediate metal conduit, electrical metal- locations except as prohibited by 334.10(3) lic tubing, Schedule SO PVC conduit, or other approved (2) To be installed or fished in air voids in masonry block means. Where passing through a floor, the cable shall be or tile walls enclosed in rigid metal conduit, intermediate metal conduit, electrical metallic tubing, Schedule 80 PVC conduit, or 334.12 Uses Not Permitted. other approved means extending at least 150 mm (6 in.) above the floor. (A) Types NM, NMC, and NMS. Types NM, NMC, and Type NMC cable installed in shallow chases or grooves NMS cables shall not be permitted as follows: in masonry, concrete, or adobe, shall be protected in accor- (1) In any dwelling or structure not specifically permitted dance with the requirements, in 300.4(F) and covered with in 334.10(1), (2), and (3) plaster, adobe, or similar finish. Exception: 7:pe NM, NMC, and NMS cable shall be per- (C) In Unfinished Basements and Crawl Spaces. Where initted in Tine I and II construction when installed within cable is run at angles with joists in unfinished basements raceways permitted to be installer) in Type I and H and crawl spaces, it shall be permissible to secure cables construction, not smaller than two 6 AWG or three 8 AWG conductors (2) Exposed in dropped or suspended ceilings in other directly to the lower edges of the joists. Smaller cables than one- and two-family and multifamily dwellings shall be run either through bored holes in joists or on run- ning boards. NM cable installed on the wall of an unfin- (3) As service-entrance cable ished basement shall be permitted to be installed in a listed (4) In commercial garages having hazardous (classified) conduit or tubing or shall be protected in accordance with locations as defined in 511.3 300.4. Conduit or tubing shall be provided with a suitable (5) In theaters and similar locations, except where permit- insulating bushing or adapter at the point the cable enters ted in 518.4(B) the raceway. The NM cable sheath shall extend through the conduit or tubing and into the outlet or device'box not less f6) In motion picture studios than 6 mm (1114 in.). The cable shall be secured within (7) In storage battery rooms 300 mm (12 in.) of the point where the cable enters the (8) In hoistways or on elevators or escalators conduit or tubing. Metal conduit, tubing, and metal outlet boxes shall be connected to an equipment: grounding con- ductor. (9) Embedded in poured cement, concrete, or aggregate (10) In hazardous (classified) locations, except where per- mitted by the following: 334.17 Through or Parallel to Framing Members.Types a. 501.10(B)(3) NM, NMC, or NMS cable shall be protected in accordance b. 502.10(B)(3) with 300.4 where installed through or parallel to framing c. 504.20 members. Grommets used as required in 300.4(B)(1) shall remain in place and be listed for the purpose of (B) Types NM and NMS. Types NM and NMS cables cable protection. shall not be used under the following conditions or in the following locations: 334.23 In Accessible Attics. The installation of cable in (1) Where exposed to corrosive fumes or vapors accessible attics or roof spaces shall also comply with (2) Where embedded in masonry, concrete, adobe, fill, or 320.23. plaster 334.24 Bending Radius. Bends in Types NM, NMC, and (3) In a shallow chase in masonry, concrete, or adobe and NMS cable shall be so made that the cable will not be covered with plaster, adobe, or similar finish damaged. The radius of the curve of the inner edge of any (4) In wet or damp locations bend during or after installation shall not be less than five times the diameter of the cable. 334.15 Exposed Work, In exposed work, except as pro- vided in 300.11(A), cable shall be installed as specified in 334.30 Securing and Supporting. Nonmetallic-sheathed 334.I5(A) through (C). cable shall be supported and secured by staples, cable ties, straps, hangers, or similar fittings designed and installed so (A) To Follow Surface.Cable shall closely follow the sur- as not to damage the cable, at intervals not exceeding 1.4 in face of the building finish or of running boards. (41/ ft) and within 300 mm (12 in.) of every outlet box, 70-186 NATIONAL ELECTRICAL.COM 2008 Edition ARTICLE 334—NONMETALLIC-SHEATHED CABLE:TYPES NM,NNIC. AND NMS 334.116 junction box, cabinet, or fitting. Flat cables shall not be 334.80 Ampaeity.The ampacity of Types NM, NMC, and stapled on edge. NMS cable shall be determined in accordance with 310.15. Sections of cable protected from physical damage by The ampacity shall be in accordance with the 60°C (140°F) raceway shall not be required to be secured within the conductor temperature rating. The 90°C (194°F) rating raceway. shall be permitted to be used for ampacity derating pur- poses, provided the final derated ampacity does not exceed (A) Horizontal Runs Through Holes and ,Notches. In that for a 60°C (140°F) rated conductor. The ampacity of other than vertical runs, cables installed in accordance with Types NM, NMC, and NMS cable installed in cable tray 300.4 shall be considered to be supported and secured shall be determined in accordance with 392.11. where such support does not exceed 1.4-m(41/2-ft)intervals Where more than two NM cables containing two or and the nonmetallic-sheathed cable is securely fastened in more current-carrying conductors are installed, without place by an approved means within 300 mm (12 in.) of maintaining spacing between the Cables, through the same each box, cabinet, conduit body, or other nonmetallic- opening in wood framing that is to be fire- or draft-stopped sheathed cable termination. using thermal insulation, caulk, or sealing foam, the allow- FPN: See 314.17(C) for support where nonmetallic boxes able ampacity of each conductor shall be adjusted in accor- are used. dance with Table 310.15(B)(2)(a) and the provisions of (B) Unsupported Cables. Nonmetallic-sheathed cable 310.15(A)(2), Exception, shalt not apply. Where more than two NM cables containing two or shall be permitted to be unsupported where the cable: more current-carrying conductors are installed in contact (1) Is fished between access points through concealed with thermal insulation without maintaining spacing be- spaces in finished buildings or structures and support- tween cables, the allowable ampacity of each conductor ing is impracticable, shall be adjusted in accordance with Table 310.15(B)(2)(a). (2) Is not more than 1.4 m (4t/2 ft) from the last point of cable support to the point of connection to a luminaire III. Construction Specifications or other piece of electrical equipment and the cable and point of connection are within an accessible ceiling. 334.100 Construction. The outer cable sheath of non- metallic-sheathed cable shall be a nonmetallic material. (C) Wiring Device Without a Separate Outlet Box. A wiring device identified for the use, without a separate out- 334.104 Conductors. The 600-volt insulated conductors let box, and incorporating an integral cable clamp shall be shall be sizes 14 AWG through 2 AWG copper conductors permitted where the cable is secured in place at intervals or sizes 12 AWG through 2 AWG aluminum or copper-clad not exceeding 1.4 m (41/2 ft) and within 300 mm (12 in.) aluminum conductors. The Communications conductors from the wiring device wall opening, and there shall be at shall comply with Part V of Article 800. least a 300 mm (12 in.) loop of unbroken cable or 150 mm (6 in.) of a cable end available on the interior side of the 334.108 Equipment Grounding Conductor. In addition finished wall to permit replacement. to the insulated conductors, the cable shall have an insu- lated, covered, or bare equipment grounding conductor. 334.40 Boxes and Fittings. 334.112 Insulation. The insulated power conductors shall (A) Boxes of Insulating Material. Nonmetallic outlet be one of the types Iisted in Table 310.13(A) that are suit- boxes shall be permitted as provided by 314.3. able for branch-circuit wiring or one that is identified for (B) Devices of Insulating Material. Switch, outlet, and use in these cables. Conductor insulation shall be rated at tap devices of insulating material shall be permitted to be 90°C (194-F). used without boxes in exposed cable wiring and for rewir- FPN: Types NM, NMC, and NMS cable identified by the ing in existing buildings where the cable is concealed and markings NM-B, NMC-B, and NMS-B meet this fished. Openings in such devices shall form a close fit requirement. around the outer covering of the cable, and the device shall 334.116 Sheath. The outer sheath of nonmetallic-sheathed fully enclose the part of the cable from which any part of cable shall comply with 334.116(A), (B), and (C). the covering has been removed. Where connections to con- ductors are by binding-screw terminals,there shall be avail- (A) Type NM. The overall covering shall be flame retar- able as many terminals as conductors. dant and moisture resistant. (C) Devices with Integral Enclosures. Wiring devices (B) Type NMC. The overall covering shall be flame re- with integral enclosures identified for such use shall be tardant, moisture resistant, fungus resistant, and corro- permitted as provided by 300.15(E). Sion resistant. 2008 Edition NATIONAL ELECTRICAL CODE 70-187 336.1 ARTICLE 336—POWER AND CONTROL TRAY CABLE:TYPE TC (C) Type NMS. The overall covering shall be flame retar- be permanently identified as an equipment grounding dant and moisture resistant. The sheath shall be applied so conductor in accordance with 250.119(B). as to separate the power conductors from the communica- Exception: Where not subject to physical damage, Type tions conductors. TC-ER shall be permitted to transition between cable trays and between cable trays and utilization equipment or de- vices for a distance not to exceed 1.8 m (6 ,t) without continuous support. The cable shall be mechanically sup- ARTICLE 336 ported where exiting the cable tray to ensure that the mini- Power and Control Tray Cable; Type TC mum bending radius is not exceeded. (8) Where installed in wet locations, Type TC cable shall also be resistant to moisture and corrosive agents. 1. General FPN: See 310.10 for temperature limitation of conductors. 336.1 Scope. This article covers the use, installation, and 336.12 Uses Not Permitted. Type TC tray cable shall not construction specifications for power and control tray cable, be installed or used as follows: Type TC. (1) Installed where it will be exposed to physical damage 336.2 Definition. (2) Installed outside a raceway or cable tray system,except as permitted in 336.10(7) Power and Control Tray Cable, Type TC. A factory as- (3) Used where exposed to direct rays of the sun, unless sembly of two or more insulated conductors, with or with- identified as sunlight resistant out associated bare or covered grounding conductors, under (4) Direct buried, unless identified for such use a nonmetallic jacket. 336.24 Bending Radius. Bends in Type TC cable shall be 1I. Installation made so as not to damage the cable. For Type TC cable without metal shielding, the minimum bending radius shall 336.10 Uses Permitted. Type TC cable shall be permitted be as follows: to be used as follows: (1) Four times the overall diameter for cables 25 mm (1) For power, lighting, control, and signal circuits. (1 in.) or less in diameter (2) In cable trays. (2) Five times the overall diameter for cables larger than (3) In raceways. 25 mm (1 in.) but not more than 50 mm (2 in.) in (4) In outdoor locations supported by a messenger wire. diameter (5) For Class 1 circuits as permitted in Parts II and III of (3) Six times the overall diameter for cables larger than Article 725. 50 mm (2 in.) in diameter (6) For non—power-limited fire alarm circuits if conductors Type TC cables with metallic shielding shall have a comply with the requirements of 760.49. minimum bending radius of not less than 12 times the cable (7) In industrial establishments where the conditions of overall diameter. maintenance and supervision ensure that only qualified 336.80 Ampaeity.The ampacity of Type TC tray cable shall persons service the installation, and where the cable is be determined in accordance with 392.11 for 14 AWG and continuously supported and protected against physical larger conductors, in accordance with 402.5 for 18 AWG damage using mechanical protection, such as struts, through 16 AWG conductors where installed in cable tray,and angles, or channels, Type TC tray cable that complies in accordance with 310.15 where installed in a raceway or as with the crush and impact requirements of Type MC messenger-supported wiring. cable and is identified for such use with the marking Type TC—ER shall be permitted between a cable tray and the utilization equipment or device.The cable shall 1111. Construction Specifications be secured at intervals not exceeding 1.8 m (6 ft). 336.100 Construction. A metallic sheath or armor as de- Equipment grounding for the utilization equipment fined in 330.116 shall not be permitted either under or over shall be provided by an equipment grounding conduc- the nonmetallic jacket. Metallic shield(s)shall be permitted for within the cable. In cables containing conductors over groups of conductors, under the outer jacket, or both. sized 6 AWG or smaller, the equipment grounding con- ductor shall be provided within the cable or, at the time 336.104 Conductors. The insulated conductors of Type of installation, one or more insulated conductors shall TC cables shall be in sizes 18 AWG to 1000 kcmil copper, 70-188 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 338—SERVICE-ENTRANCE CABLE:TYPES SE AND USE 338.12 nickel, or nickel-coated copper, and sizes 12 AWG through conductors and shall be installed in accordance with 230.6, 1000 kcrail aluminum or copper-clad aluminum. Insulated 230.7, and Parts II, III, and IV of Article 230. conductors of sizes 14 AWG, and larger copper, nickel, or • nickel-coated copper, and sizes 12 AWG through 1000 kc- (B) Branch Circuits or Feeders. mil aluminum or copper-clad aluminum shall be one of the (1) Grounded Conductor Insulated. Type SE service- types listed in Table 310.13(A) or Table 310.13(B) that is entrance cables shall be permitted in wiring systems where suitable for branch circuit and feeder circuits or one that is all of the circuit conductors of the cable are of the thermo- identified for such use. Set or thermoplastic type. (A) Fire Alarm Systems. Where used for fire alarm sys- (2) Grounded Conductor Not Insulated. Type SE tems, conductors shall also be in accordance with 760.49. service-entrance cable shall be permitted for use where the (B) Thermocouple Circuits.Conductors in Type TC cable insulated conductors are used for circuit wiring and the used for thermocouple circuits in accordance with Part III uninsulated conductor is used only for equipment ground- of Article 725 shall also be permitted to be any of the ing purposes. materials used for thermocouple extension wire. Exception: Uninsulated conductors shall be permitted as a (C) Class I Circuit Conductors. Insulated conductors of grounded conductor in accordance with 250.32 and 18 AWG and 16 AWG copper shall also be in accordance 250.140 where the uninsulated grounded conductor of the with 725.49. cable originates in service equipment, and 225.30 through 225.40. 336.116 Jacket. The outer jacket shall be a flame- retardant, nonmetallic material. (3) Temperature Limitations. Type SE service-entrance cable used to supply appliances shall not be subject to con- 336.120 Marking.There shall be no voltage marking on a ductor temperatures in excess of the temperature specified Type TC cable employing thermocouple extension wire. for the type of insulation involved. (4) Installation Methods for Branch Circuits and Feeders. ARTICLE 338 (a) Interior Installations. In addition to the provisions of this article, Type SE service-entrance cable used for in- terior wiring shall comply with the installation require- Types SE and USE ments of Part iI of Article 334. FPN: See 3 10.10 for temperature limitation of conductors. I. General (b) Exterior Installations. In addition to the provisions 338.1 Scope. This article covers the use, installation, and of this article, service-entrance cable used for feeders or construction specifications of service-entrance cable. branch circuits, where installed as exterior wiring, shall be installed in accordance with Part I of Article 225.The cable 338.2 Definitions. shall be supported in accordance with 334.30. Type USE Service-Entrance Cable. A single conductor or multicon- cable installed as underground feeder and branch circuit ductor assembly provided with or without an overall cov- cable shall comply with Part II of Article 340. ering, primarily used for services, and of the following • types: 338.12 Uses Not Permitted. Type SE. Service-entrance cable having a flame-retardant, (A) Service-Entrance Cable. Service-entrance cable(SE) moisture-resistant covering. shall not be used under the following conditions or in the Type USE. Service-entrance cable, identified for under- following locations: ground use, having a moisture-resistant covering, but not (1) Where subject to physical damage unless protected in required to have a flame-retardant covering, accordance with 230.50(A) (2) Underground with or without a raceway II. Installation (3) For exterior branch circuits and feeder wiring unless the installation complies with the provisions of Part I of 338.10 Uses Permitted. Article 225 and is supported in accordance with 334.30 (A) Service-Entrance Conductors. Service-entrance or is used as messenger-supported wiring as permitted cable shall be permitted to be used as service-entrance in Part IT of Article 396 2008 Edition NATIONAL ELECTRICAL CODE 70--189 338.24 ARTICLE 340—UNDERGROUND FEEDER AND BRANCH-CIRCUIT CABLE:TYPE OF (B) Underground Service-Entrance Cable. Underground tors with an integral or an overall covering of nonmetallic service-entrance cable (USE) shall not be used under the material suitable for direct burial in the earth. following conditions or in the following locations: (1) For interior wiring 340.6 Listing Requirements.Type OF cable shall be listed. (2) For aboveground installations except where USE cable emerges from the ground and is terminated in an enclo- H. Installation sure at an outdoor location and the cable is protected in accordance with 300.5(D) 340.10 Uses Permitted. Type OF cable shall be permitted (3) As aerial cable unless it is a multiconductor cable iden- as follows: tified for use aboveground and installed as messenger- (1) For use underground, including direct burial in the supported wiring in accordance with 225.10 and Part II earth. For underground requirements, see 300.5. of Article 396 (2) As single-conductor cables. Where installed as single- conductor cables, all conductors of the feeder grounded 338.24 Bending Radius. Bends in Types USE and SE conductor or branch circuit, including the grounded cable shall be so made that the cable will not be damaged. conductor and equipment grounding conductor, if any, The radius of the curve of the inner edge of any bend, shall be installed in accordance with 300.3. during or after installation, shall not be less than five times (3) For wiring in wet, dry, or corrosive locations under the the diameter of the cable. recognized wiring methods of this Code. (4) Installed as nonmetallic-sheathed cable. Where so in- III. Construction stalled, the installation and conductor requirements shall comply with Parts II and III of Article 334 and 338.100 Construction. Cabled, single-conductor, Type shall be of the multiconductor type. USE constructions recognized for underground use shall be permitted to have a bare copper conductor cabled with the (5) For solar photovoltaic systems in accordance with 690.31. assembly. Type USE single, parallel, or cabled conductor as- (6) As single-conductor cables as the nonheating leads for semblies recognized for underground use shall he permitted to heating cables as provided in 424.43. have a bare copper concentric conductor applied. These con- (7) Supported by cable trays. Type OF cable supported by structions shall not require an outer overall covering. cable trays shall be of the multiconductor type. FPN: See 230.41. Exception, item (2), for directly buried, FPN: See 3 10.10 for temperature limitation of conductors. uninsulated service-entrance conductors. Type SE or USE cable containing two or more conduc- 340.12 Uses Not Permitted. Type OF cable shall not be used as follows: tors shall be permitted to have one conductor uninsulated. (1) As service-entrance cable 338.120 Marking. Service-entrance cable shall be marked (2) In commercial garages as required in 310.11. Cable with the neutral conductor (3) In theaters and similar locations smaller than the ungrounded conductors shall be so marked. (4) In motion picture studios (5) In storage battery rooms (6) In hoistways or on elevators or escalators (7) In any hazardous (classified) location, except as oth- ARTICLE 340 erwise permitted in this Cade Underground Feeder and Branch-Circuit (8) Embedded in poured cement, concrete, or aggregate, Cable: Type OF except where embedded in plaster as nonheating leads where permitted in 424.43 1. General (9) Where exposed to direct rays of the sun, unless iden- tified as sunlight resistant 340.1 Scope. This article covers the use, installation, and (10) Where subject to physical damage construction specifications for underground feeder and (11) As overhead cable, except where installed as branch-circuit cable, Type OF messenger-supported wiring in accordance with Part 340.2 Definition. II of Article 396 Underground Feeder and Branch-Circuit Cable, Type 340.24 Bending Radius. Bends in Type OF cable shall be UR A factory assembly of one or more insulated conduc- so made that the cable is not damaged. The radius of the 70-190 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 342—INTERMEDIATE METAL CONDUIT•TYPE IMC 342.26 curve of the inner edge of any bend shall not be less than (B) Corrosion Environments. IMC, elbows, couplings, five times the diameter of the cable. and fittings shall be permitted to be installed in concrete, in direct contact with the earth, or in areas subject to severe 340.80 Ampacity.The ampacity of Type OF cable shall be corrosive influences where protected by corrosion protec- that of 60°C(140°F)conductors in accordance with 310.15. tion and judged suitable for the condition. III. Construction Specifications (C) Cinder Fill. IMC shall be permitted to be installed in or under cinder fill where subject to permanent moisture 340.104 Conductors. The conductors shall be sizes 14 where protected on all sides by a layer of noncinder con- AWG copper or 12 AWG aluminum or copper-clad alumi- crete not less than 50 mm (2 in.) thick; where the conduit is num through 4/0 AWG, not less than 450 mm (18 in.) under the fill; or where protected by corrosion protection and judged suitable for 340.108 Equipment Grounding Conductor. In addition the condition. to the insulated conductors, the cable shall be permitted to have an insulated or bare equipment grounding conductor. (D) Wet Locations. All supports,bolts, straps,screws,and so forth, shall be of corrosion-resistant materials or pro- 340.112 Insulation. The conductors of Type OF shall be tected against corrosion by corrosion-resistant materials. one of the moisture-resistant types listed in Table 310.13(A) that is suitable for branch-circuit wiring or one FPN: See 300.6 for protection against corrosion. that is identified for such use. Where installed as a substi- tute wiring method for NM cable, the conductor insulation 342.14 Dissimilar Metals. Where practicable, dissimilar shall be rated 90°C (194°F), metals in contact anywhere in the system shall be avoided to eliminate the possibility of galvanic action. 340.116 Sheath.The overall covering shall be flame retar- Aluminum fittings and enclosures shall be permitted to dant; moisture, fungus, and corrosion resistant; and suitable be used with IMC. for direct burial in the earth. 342.20 Size. (A) Minimum. IMC smaller than metric designator 16 ARTICLE 342 (trade size 1/2) shall not be used. Intermediate Metal Conduit; Type IMC (B) Maximum. IMC larger than metric designator 103 (trade size 4) shall not be used. I. General FPN: See 300.1(C) for the metric designators and trade sizes.These are for identification purposes only and do not 342.1 Scope. This article covers the use, installation, and relate to actual dimensions. construction specifications for intermediate metal conduit (IMC) and associated fittings. 342.22 Number of Conductors. The number of conduc- 342.2 Definition. tors shall not exceed that permitted by the percentage fill specified in Table 1, Chapter 9. Intermediate Metal Conduit (IMC). A steel threadable Cables shall be permitted to be installed where such use raceway of circular cross section designed for the physical is not prohibited by the respective cable articles. The num- protection and routing of conductors and cables and for use ber of cables shall not exceed the allowable percentage fill as an equipment grounding conductor when installed with specified in Table 1, Chapter 9. its integral or associated coupling and appropriate fittings. 342.24 Bends — How Made. Bends of IMC shall be so 342.6 Listing Requirements. IMC, factory elbows and made that the conduit will not be damaged and the internal couplings, and associated fittings shall be listed. diameter of the conduit will not be effectively reduced. The radius of the curve of any field bend to the centerline of the 11. Installation conduit shall not be less than indicated in Table 2, Chapter 9. 342.10 Uses Permitted. 342.26 Bends—Number in One Run.There shall not be (A) All Atmospheric Conditions and Occupancies. Use more than the equivalent of four quarter bends(360 degrees of IMC shall be permitted under all atmospheric conditions total) between pull points, for example, conduit bodies and and occupancies. boxes. 2008 Edition NATIONAL ELECTRICAL CODE 70-191 342.28 ARTICLE 344—RIGID METAL CONDUCT:TYPE RMC 342.28 Reaming and Threading. All cut ends shall be 342.42 Couplings and Connectors. reamed or otherwise finished to remove rough edges. Where conduit is threaded in the field, a standard cutting die with a (A) Threadless.Threadless couplings and connectors used with conduit shall be made tight. Where buried in masonry taper of 1 in 16 (%4 in. taper per foot) shall be used. or concrete, they shall be the concretetight type. Where FPN: See ANSUASME B.1.20.1-1983, Slandard for Pipe installed in wet locations, they shall comply with 314.15. Threads. General Purpose (Inch). Threadless couplings and connectors shall not be used on threaded conduit ends unless listed for the purpose. 342.30 Securing and Supporting. IMC shall be installed as a complete system in accordance with 300.18 and shall (B) Running Threads. Running threads shall not be used on conduit for connection securely fastened in place and supported in accordance an at couplings. with 342.30(A) and (B), or permitted to be unsupported in 342.46 Bushings. Where a conduit enters a box, fitting, or accordance with 342.30(C). other enclosure, a bushing shall be provided to protect the wire from abrasion unless the design of the box, fitting, or (A) Securely Fastened. Each IMC shall be securely fas enclosure is such as to afford equivalent protection. tened within 900 mm (3 ft) of each outlet box, junction box, device box, cabinet, conduit body, or other conduit FPN: See 300.4(G) for the protection of conductors 4 termination. Fastening shall be permitted to be increased to AWG and larger at bushings. a distance of 1.5 In (5 ft) where structural members do not n ft). Where ap- i readily permit fastening within 900 mm (3 n accordance Splices and Taps. Splices and taps shall be made accordance with 300.15. proved, conduit shall not be required to be securely fas- tened within 900 mm (3 ft) of the service head for above- 342.60 Grounding. IMC shall be permitted as an equip- the-roof termination of a mast. ment grounding conductor. (B) Supports. IMC shall be supported in accordance with one of the following: 11I. Construction Specifications (l) Conduit shall be supported at intervals not exceeding 3 m 342.120 Marking. Each length shall be clearly and Jura- 00 ft)• bly marked at least every 1.5 m (5 ft) with the letters IMC. (2) The distance between supports for straight runs of con- Each length shall be marked as required in 110.21. duit shall be permitted in accordance with Table 344.30(B)(2), provided the conduit is made up with 342.130 Standard Lengths. The standard length of IMC threaded couplings and such supports prevent transmis- shall be 3.05 m (10 ft), including an attached coupling, and sion of stresses to termination where conduit is de- each end shall be threaded. Longer or shorter lengths with flected between supports. or without coupling and threaded or unthreaded shall be (3) Exposed vertical risers from industrial machinery or permitted. fixed equipment shall be permitted to be supported at intervals not exceeding 6 m (20 ft) if the conduit is made up with threaded couplings, the conduit is sup- ported and securely fastened at the top and bottom of ARTICLE 344 the riser, and no other means of intermediate support is Rigid Metal Conduit. Type RMC readily available. (4) Horizontal runs of IMC supported by openings through 1. General framing members at intervals not exceeding 3 m (10 ft) and securely fastened within 900 mm (3 ft) of termina- 344.1 Scope. This article covers the use, installation, and lion points shall be permitted. construction specifications for rigid metal conduit (RMC) and associated fittings. (C) Unsupported Raceways:.Where oversized,concentric or eccentric knockouts are not encountered,'I)Ppe IMC shall 344.2 Definition. be permitted to be unsupported where the raceway is not Rigid Metal Conduit (RMC). A threadable raceway of more than 450 mm (18 in.) and remains in unbroken circular cross section designed for the physical protection lengths (without coupling). Such raceways shall terminate and routing of conductors and cables and for use as an in an outlet box,junction box,device box,cabinet, or other equipment grounding conductor when installed with its in- termination at each end of the raceway. tegral or associated coupling and appropriate fittings. RMC 70-192 NATIONAL ELECTRICAL CODE 2(X)8 Edition ARTICLE 344—RIGID METAL CONDUIT:TYPE RMC 344.30 is generally made of steel (ferrous) with protective coatings 344,14 Dissimilar Metals. Where practicable, dissimilar or aluminum (nonferrous). Special use types are red brass metals in contact anywhere in the system shall be avoided and stainless steel, to eliminate the possibility of galvanic action. Aluminum fittings and enclosures shall be permitted to be used with 344.6 Listing Requirements. RMC, factory elbows and steel RMC, and steel fittings and enclosures shall be per- couplings, and associated fittings shall be listed. milted to be used with aluminum RMC where not subject to severe corrosive influences. II. Installation 344.20 Size. 344.10 Uses Permitted. (A) Minimum. RMC smaller than metric designator 16 (A) Atmospheric Conditions and Occupancies. (trade size 1/2) shall not be used. (1) Galvanized Steel and Stainless Steel RMC. Galva- Exception: For enclosing the leads of motors as permitted nized steel and stainless steel RMC shall be permitted un- in 430.245(B). der all atmospheric conditions and occupancies. (2) Red Brass RMC. Red brass RMC shall be permitted to (B) Maximum. RMC larger than metric designator 155 be installed for direct burial and swimming pool applications. (trade size 6) shall not be used. (3) Aluminum RMC. Aluminum RMC shall be permitted FPN: See 300.1(C) for the metric designators and trade to be installed where judged suitable for the environment. sizes.These are for identification purposes only and do not relate actual dimensions. Rigid aluminum conduit encased in concrete or in direct m contact with the earth shall be provided with approved 344.22 Number of Conductors. The number of conduc- supplementary corrosion protection. tars shall not exceed that permitted by the percentage fill (4) Ferrous Raceways and Fittings. Ferrous raceways specified in Table 1, Chapter 9. and fittings protected from corrosion solely by enamel shall Cables shall be permitted to be installed where such use be permitted only indoors and in occupancies not subject to is not prohibited by the respective cable articles. The num- severe corrosive influences. ber of cables shall not exceed the allowable percentage fill (B) Corrosive Environments. specified in Table I, Chapter 9. (1) Galvanized Steel, Stainless Steel, and Red Brass 344.24 Bends —How Made. Bends of RMC shall be so RMC,Elbows, Couplings,and Fittings.Galvanized steel, made that the conduit will not be damaged and so that the stainless steel, and red brass RMC elbows, couplings, and internal diameter of the conduit will not be effectively re- fittings shall be permitted to be installed in concrete, in duced. The radius of the curve of any field bend to the direct contact with the earth, or in areas subject to severe centerline of the conduit shall not be less than indicated in corrosive influences where protected by corrosion protec- Table 2, Chapter 9. tion and judged suitable for the condition. 344.26 Bends—Number in One Run.There shall not be (2) Supplementary Protection of Aluminum RMC.Alu- more than the equivalent of four quarter bends(360 degrees minum RMC shall be provided with approved supplemen- total) between pull points, for example, conduit bodies and tary corrosion protection where encased in concrete or in boxes. direct contact with the earth. (C) Cinder Fill. Galvanized steel, stainless steel, and red 344.28 Reaming and Threading. All cut ends shall be brass RMC shall be permitted to be installed in or under reamed or otherwise finished to remove rough edges. cinder fill where subject to permanent moisture where pro- Where conduit is threaded in the field, a standard cutting tected on all sides by a layer of noncinder concrete not less die with a 1 in 16 taper(1/4-in. taper per foot)shall be used. than 50 mm (2 in.) thick; where the conduit is not less than FPN: See ANSIIASME 13.1.20.1-1983, 5tandarri far Pipe 450 mm (18 in.) under the fill; or where protected by cor- Threads, General Purpose (Inch). rosion protection and judged suitable for the condition. (D) Wet Locations. All supports,bolts,straps, screws, and 344.30 Securing and Supporting. AMC shall be installed so forth, shall be of corrosion-resistant materials or pro- as a complete system in accordance with 300.18 and shall tected against corrosion by corrosion-resistant materials. be securely fastened in place and supported in accordance with 344.30(A) and (B) or permitted to be unsupported in FPN: See 300.6 for protection against corrosion. accordance with 344.30(C). 2008 Edilion NATIONAL ELECTRICAL.CODE 70-193 344.42 ARTICLE 349, FLEXIBLE METAL CONDUIT:TYPE FMC (A) Securely Fastened. RMC shall be securely fastened 344.42 Couplings and Connectors. within 900 mm (3 ft) of each outlet box, junction box, device box, cabinet, conduit body, or other conduit fermi- (A) Threadless.Threadless couplings and connectors used with conduit shall be made tight.Where buried in masonry nation. Fastening shall be permitted to be increased to a or concrete, they shall be the concretetight type. Where distance of 1.5 m (5 ft) where structural members do not installed in wet locations, they shall comply with 314.15. readily permit fastening within 900 mm (3 ft). Where ap- Threadless couplings and connectors shall not be used on proved, conduit shall not be required to be securely fas- threaded conduit ends unless listed for the purpose. tened within 900 mm (3 ft) of the service head for above- the-roof termination of a mast. (B) Running Threads. Running threads shall not be used (B) Supports. RMC shall be supported in accordance with on conduit for connection at couplings. one of the following: 344.46 Bushings.Where a conduit enters a box, fitting, or (1) Conduit shall be supported at intervals not exceeding 3 m other enclosure, a bushing shall be provided to protect the (10 ft). wire from abrasion unless the design of the box, fitting, or (2) The distance between supports for straight runs of con- enclosure is such as to afford equivalent protection. duit shall be permitted in accordance with Table FPN: See 300.4(G)for the protection of conductors sizes 4 344.30(B)(2), provided the conduit is made up with AWG and larger at bushings. threaded couplings and such supports prevent transmis- sion of stresses to termination where conduit is de- 344.56 Splices and Taps. Splices and taps shall be made flected between supports. in accordance with 300.15. Table 344.30(B)(2) Supports for Rigid Metal Conduit 344.60 Grounding. RMC shall be permitted as an equip- ment grounding conductor. Maximum Distance Between Rigid Metal Conduit Size Conduit Supports III. Construction Specifications Metric 344.120 Marking. Each length shall be clearly and dura- Designator 'Made Size m ft bly identified in every 3 m (10 ft) as required in the first 1(x21 /z-'/4 3.0 10 sentence of 110.21. Nonferrous conduit of corrosion- ] 27 1 3.7 12 resistant material shall have suitable markings. 35--41 1'!a-1'/z 4.3 14 53-63 2-2'!z 49 16 344.130 Standard Lengths. The standard length of RMC 78 and larger 3 and larger 6.1 20 shall be 3.05 m(10 ft), including an attached coupling, and each end shall be threaded. Longer or shorter lengths with (3) Exposed vertical risers from industrial machinery or or without coupling and threaded or unthreaded shall be fixed equipment shall be permitted to be supported at permitted. intervals not exceeding 6 m (20 ft) if the conduit is made up with threaded couplings, the conduit is sup- ported and securely fastened at the top and bottom of the riser, and no other means of intermediate support is ARTICLE 348 readily available. Flexible Metal Conduit: Type FMC (4) Horizontal runs of RMC supported by openings through framing members at intervals not exceeding 3 m(10 ft)and securely fastened within 900 mm (3 ft)of 1. General termination points shall be permitted. 348.1 Scope. This article covers the use, installation, and (C) Unsupported Raceways.Where oversized,concentric Construction specifications for flexible metal conduit or eccentric knockouts are not encountered, Type RMC (FMC) and associated fittings. shall be permitted to be unsupported where the raceway is not more than 450 mm (1$ in.) and remains in unbroken 348.2 Definition. lengths (without coupling). Such raceways Shall terminate Flexible Metal Conduit (FMC). A raceway of circular in an outlet box,junction box, device box,cabinet,or other cross section made of helically wound, formed, interlocked termination at each end of the raceway. metal strip. 70-194 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 348—FLEXIBLE METAL CONDUIT:TYPE FMC 348.30 348.6 Listing Requirements. FMC and associated fittings (B) Maximum. FMC larger than metric designator 103 shall be listed. (trade size 4) shall not be used. FPN: See 300.1(C) for the metric designators and trade 1I. Installation sizes.These are for identification purposes only and do not relate to actual dimensions. 348.10 Uses Permitted. FMC shall be permitted to be used in exposed and concealed locations. 348.22 Number of Conductors. The number of conduc- tors shall not exceed that permitted by the percentage fill 348.12 Uses Not Permitted. FMC shall not be used in the specified in Table 1, Chapter 9, or as permitted in Table following: 348.22, or for metric designator 12 (trade size "Is). (1) In wet locations Cables shall be permitted to be installed where such use (2) In hoistways, other than as permitted in 620.21(A)(1) is not prohibited by the respective cable articles. The num- (3) In storage battery rooms ber of cables shall not exceed the allowable percentage fill (4) In any hazardous (classified) location except as permit- specified in Table 1, Chapter 9. ted by other articles in this Code 348.24 Bends — How Made. Bends in conduit shall be (5) Where exposed to materials having a deteriorating ef- made so that the conduit is not damaged and the internal feet on the installed conductors, such as oil or gasoline diameter of the conduit is not effectively reduced. Bends (6) Underground or embedded in poured concrete or aggre- shall be permitted to be made manually without auxiliary gate equipment. The radius of the curve to the centerline of any (7) Where subject to physical damage bend shall not be less than shown in Table 2, Chapter 9 using the column "Other Bends." 348.20 Size. 348.26 Bends—Number in One Run. There shall not be (A) Minimum. FMC less than metric designator 16 (trade more than the equivalent of tour quarter bends(360 degrees size Vz) shall not be used unless permitted in 348.20(A)(1) total) between pull points, for example, conduit bodies and through (A)(5) for metric designator 12 (trade size ?/s). boxes. (1) For enclosing the leads of motors as permitted in 430.245(8) 348.28 'Trimming. All cut ends shall be trimmed or other- (2) In lengths not in excess of 1.8 m (6 ft) for any of the wise finished to remove rough edges, except where fittings following uses: that thread into the convolutions are used. a. For utilization equipment b. As part of a listed assembly 348.30 Securing and Supporting. FMC shall be securely c. For tap connections to luminaires as permitted in fastened in place and supported in accordance with 410.117(C) 348.30(A) and (B). (3) For manufactured wiring systems as permitted in (A) Securely Fastened. FMC shall be securely fastened in 604.6(A) place by an approved means within 300 mm (12 in.) of (4) In hoistways as permitted in 620.21(A)(1) each box, cabinet, conduit body, or other conduit termina- (5) As part of a listed assembly to connect wired luminaire tion and shall be supported and secured at intervals not to sections as permitted in 410.137(C) exceed 1.4 m (41/ ft). Table 348.22 Maximum Number of Insulated Conductors in Metric Designator 12 (Trade Size ifs) Flexible Metal Conduit Types RFH-2, SF-2 Types TF,XHHW,TW Types TFN,THHN,THWN Types FEP, FEBP, PF, PGF Fittings Fittings Fittings Fittings Fittings Fittings Fittings Fittings Size Inside Outside Inside Outside Inside Outside Inside Outside (AWG) Conduit Conduit Conduit Conduit Conduit Conduit Conduit Conduit 18 2 3 3 5 5 8 5 8 16 l 2 3 4 4 6 4 6 14 1 2 2 3 3 4 3 4 12 — — l 2 2 3 2 3 10 — — 1 1 1 1 1 2 *In addition, one insulated, covered, or bare equipment grounding conductor of the same size shall be permitted. 2008 Edition NATIONAL ELECTRICAL CODE 70-195 348.42 ARTICLE 350 LIQUIDTIGHT FLEXIBLE METAL CONDUIT:TYPE LFMC Exception No. 1: Where FMC is fished between access 350.2 Definition. points through concealed spaces in finished buildings or Liquidtight Flexible Metal Conduit (LFMC). A raceway structures and supporting is impractical. of circular cross section having an outer liquidtight, non- Exception No. 2: Where flexibility is necessary after instal- metallic, sunlight-resistant jacket over an inner flexible lation, lengths shall not exceed the following: metal core with associated couplings, connectors, and fit- (I) 900 mm (3 ft)for metric designators 16 through 35 tings for the installation of electric conductors. (trade sizes 1/2 through 1 f/4) (2) 1200 mm (4 ft)for metric designators 41 through 53 350.6 Listing Requirements. LFMC and associated fit- (trade sizes 1112 through 2) tings shall be listed. (3) 1500 mm (5 ft)for metric designators 63 (trade size 2112) and larger II. Installation Exception No. 3: Lengths not exceeding 1.8 m (6 ft)from a 350,10 Uses Permitted. LFMC shall be permitted to be luminaire terminal connection for tap connections to lumi- used in exposed or concealed locations as follows: naires as permitted in 410.117(C). (1) Where conditions of installation, operation, or mainte- Exception No. 4: Lengths not exceeding 1.8 m (6 ft)from nance require flexibility or protection from liquids, va- the last point where the raceway is securely fastened for pors, or solids connections within an accessible ceiling to luminaire(s) or (2) As permitted by 501.1O(B),502.10, 503.10, and 504.20 other equipment. and in other hazardous (classified) locations where spe- (B) Supports.Horizontal runs of)AMC supported by open- cifically approved, and by 553.7(B) ings through framing members at intervals not greater than (3) For direct burial where listed and marked for the 1.4 m(41/2 ft) and securely fastened within 300 mm(12 in.) purpose of termination points shall be permitted. 350.12 Uses Not Permitted. LFMC shall not be used as 348.42 Couplings and Connectors. Angle connectors follows: shall not be used for concealed raceway installations. (1) Where subject to physical damage (2) Where any combination of ambient and conductor tem- 348.56 Splices and Taps. Splices and taps shall be made perature produces an operating temperature in excess in accordance with 300.15. of that for which the material is approved 348.60 Grounding and Bonding. Where used to connect 350.20 Size. equipment where flexibility is required after installation, an equipment grounding conductor shall be installed. (A) Minimum. LFMC smaller than metric designator 16 Where flexibility is not required after installation, FMC (trade size 1/z) shall not be used. shall be permitted to be used as an equipment grounding Exception: LFMC of metric designator 12 (trade size i/s) conductor when installed in accordance with 250.118(5). Where required or installed, equipment grounding con- ductors shall be installed in accordance with 250.134(B). (B) Maximum.The maximum size of LFMC shall be met- Where required or installed, equipment bonding jump- ric designator 103 (trade size 4). ers shall be installed in accordance with 250.102. FPN: See 300.1(C) for the metric designators and trade sizes.These are for identification purposes only and do not relate to actual dimensions. ARTICLE 350 350.22 Number of Conductors or Cables. Liquidtight Flexible Metal Conduit: (A) Metric Designators 16 through 103 (Trade Sizes 1/2 Type LFMC through 4). The number of conductors shall not exceed that permitted by the percentage fill specified in Table 1, I. General Chapter 9. Cables shall be permitted to be installed where such use 350.1 Scope. This article covers the use, installation, and is not prohibited by the respective cable articles. The num- construction specifications for liquidtight flexible metal ber of cables shall not exceed the allowable percentage fill conduit (LFMC) and associated fittings. specified in Table 1, Chapter 9. 70-196 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 352 RIGID POLYVINYL CHLORIDE CONDUIT.TYPE PVC 352.10 (B) Metric Designator 12 (Trade Size 31a).The number of 350.56 Splices and Taps. Splices and taps shall be made conductors shall not exceed that permitted in Table 348.22, in accordance with 300.15. "Fittings Outside Conduit" columns. 350.60 Grounding and Bonding. Where used to connect 350.24 Bends—How Made. Bends in conduit shall be so equipment where flexibility is required after installation, an made that the conduit will not be damaged and the internal equipment grounding conductor shall be installed. diameter of the conduit will not be effectively reduced. Where flexibility is not required after installation, Bends shall be permitted to be made manually without aux- LFMC shall be permitted to be used as an equipment iliary equipment. The radius of the curve to the centerline grounding conductor when installed in accordance with of any bend shall not be less than required in Table 2, 250.118(6). Chapter 9 using the column "Other Bends." Where required or installed, equipment grounding con- ductors shall be installed in accordance with 250.134(B). 350.26 Bends—Number in One Run.There shall not be Where required or installed, equipment bonding jump- more than the equivalent of four quarter bends(360 degrees ers shall be installed in accordance with 250.102. total) between pull points, for example, conduit bodies and FPN: See 501.30(B), 502.30(B). 503.30(B), 505.25(B), boxes. and 50625($)for types of equipment grounding conductors. 350.30 Securing and Supporting. LFMC shall be se- curely fastened in place and supported in accordance with III. Construction Specifications 350.30(A) and (B). 350.120 Marking. LFMC shall be marked according to 110.21. The trade size and other information required by (A) Securely Fastened. LFMC shall be securely fastened the listing shall also be marked on the conduit. Conduit in place by an approved means within 300 mm (]2 in.) of suitable for direct burial shall be so marked. each box, cabinet, conduit body, or other conduit termina- tion and shall be supported and secured at intervals not to exceed 1.4 m (41/2 ft). Exception No. 1: Where LFMC is fished between access ARTICLE 352 points through concealed spaces in finished buildings or structures and supporting is impractical. 1 Rigid Polyvinyl Chloride Conduit: Exception No. 2: Where flexibility is necessary after instal- J Type PVC lation, lengths shall not exceed the following: (1) 900 mm (3 ft)for metric designators 16 through 35 1. General (trade sizes 112 through 1114) 352.1 Scope. This article covers the use, installation, and (2) 1200 mm (4 ft)for metric designators 41 through 53 construction specifications for rigid polyvinyl chloride con- (trade sizes 1115 through 2) duit (PVC) and associated fittings. (3) 1500 mm (5 ft)for metric designators 63 (trade size FPN: Refer to Article 353 for High Density Polyethylene 21/2) and larger Conduit:Type HDPB,and Article 55 for Reinforced Ther- Exception No. 3: Lengths not exceeding 1.8 m(6 ft)from a mosetting Resin Conduit:Type RTRC. huninaire terminal connection for tap conductors to lunti naires, as permitted in 410.117(0). 352.2 Definition. Exception No. 4: Lengths not exceeding 1.8 In (6 ft)from Rigid Polyvinyl Chloride Conduit(PVC).A rigid nonme- the last point where the raceway is securely fastened for tallic Conduit(RNC) of circular cross section, with integral connections within an accessible ceiling to hani naire(s) or or associated couplings, connectors, and fittings for the in- other equipment. stallation of electrical conductors and cables. (B) Supports. Horizontal runs of LFMC supported by 352.6 Listing Requirements, PVC conduit, factory el- openings through framing members at intervals not greater bows, and associated fittings shall be listed. than 1.4 m (41/2 ft) and securely fastened within 300 mm (12 in.) of termination points shall be permitted. 11. Installation 350.42 Couplings and Connectors. Angle connectors 352.10 Uses Permitted. The use of PVC conduit shall be shall not be used for concealed raceway installations. permitted in accordance with 352.10(A) through (H). 2008 Edition NATIONAL ELECTRICAL CODE 70.197 352.12 ARTICLE 352—RIGID POLYVINYL CHLORIDE CONDUIT:TYPE PVC FPN: Extreme cold may cause some nonmetallic conduits (D) Ambient Temperatures. Where subject to ambient to become brittle and, therefore, more susceptible to dam- temperatures in excess of 50°C (122°F) unless listed age from physical contact. otherwise. (A) Concealed. PVC conduit shall be permitted in walls, (E) Insulation Temperature Limitations. For conductors floors, and ceilings. or cables operating at a temperature higher than the PVC (B) Corrosive Influences.PVC conduit shall be permitted conduit listed operating temperature rating. in locations subject to severe corrosive influences as cov- Exception: Conductors or cables rated at a temperature ered in 300.6 and where subject to chemicals for which the higher than the PVC conduit listed temperature rating shall materials are specifically approved. be permitted to be installed in PVC conduit, provided they (C) Cinders. PVC conduit shall be permitted in cinder fill. are not operated at a temperature higher than the PVC conduit listed temperature rating. (D) Wet Locations. PVC conduit shall be permitted in portions of dairies, laundries, canneries, or other wet loco- (F) Theaters and Similar Locations.In theaters and simi- tions, and in locations where walls are frequently washed, Iar locations, except as provided in S 18.4 and 520.5. the entire conduit system, including boxes and fittings used 352.20 Size. therewith, shall be installed and equipped so as to prevent water from entering the conduit.All supports, bolts, straps, (A) Minimum. PVC conduit smaller than metric designa- screws, and so forth, shall be of corrosion-resistant materi- for 16 (trade size '/2) shalt not be used. als or be protected against corrosion by approved corrosion-resistant materials. (B) Maximum. PVC conduit larger than metric designator 155 (trade size 6) shall not be used. (E) Dry and Damp Locations. PVC Conduit shall be per- FPN: The trade sizes and metric designators are for iden- mitted for use in dry and damp locations not prohibited by tifcation purposes only and do not relate to actual dimen- 352.12. lions. See 300.1(0. (F) Exposed. PVC conduit shall be permitted for exposed 352,22 Number of Conductors. The number of conduc- work. PVC conduit used exposed in areas of physical dam- tors shall not exceed that permitted by the percentage fill age shall be identified for the use. specified in Table 1, Chapter 9. FPN: PVC Conduit, Type Schedule 80, is identified for Cables shall be permitted to be installed where such use areas of physical damage. is not prohibited by the respective cable articles. The num- ber of cables shall not exceed the allowable percentage fill (G) Underground Installations.For underground installa- specified in Table 1, Chapter 9. tions, homogenous and nonhornogenous PVC shall be per- mitted for direct burial and underground encased in con- 352.24 Bends—How Made. Bends shall be so made that erete. See 300.5 and 300.50. the conduit will not be damaged and the internal diameter of the conduit will not be effectively reduced. Field bends (H) Support of Conduit Bodies. PVC conduit shall be shall be made only with bending equipment identified for the permitted to support nonmetallic conduit bodies not larger purpose. The radius of the curve to the centerline of such than the largest trade size of an entering raceway. These bends shall not be less than shown in Table 2, Chapter 9. conduit bodies shall not support luminaires or other equip- ment and shall not contain devices other than splicing de- 352,26 Bends—Number in One Run.There shall not be vices as permitted by 110.14(B) and 314.16(C)(2). more than the equivalent of four quarter bends (360 degrees 352.12 Uses Not Permitted.PVC conduit shall not be used total) between pull points, for example, conduit bodies and boxes. under the conditions specified in 352.12(A) through (F). (A) Hazardous (Classified) Locations. In any hazardous 352.28 Trimming, All cut ends shall be trimmed inside (classified) location,except as permitted by other articles of and outside to remove rough edges. . this Code. 352.30 Securing and Supporting. PVC conduit shall be (B) Support of Luminaires. For the support of luminaires installed as a complete system as provided in 300.18 and shall or other equipment not described in 352.10(H). be fastened so that movement from thermal expansion or con- traction is permitted. PVC conduit shall be securely fastened (C) Physical Damage. Where subject to physical damage and supported in accordance with 352.30(A) and (B) or per- unless identified for such use. mitted to be unsupported in accordance with 352.30(C). 70-198 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 352-RIGID POLYVINYL CHLORIDE CONDUIT: TYPE PVC 352.56 (A) Securely Fastened.PVC conduit shall be securely fas- (C) Unsupported Raceways.Where oversized,concentric tened within 900 mm (3 ft)of each outlet box,junction box, Or eccentric knockouts are not encountered, PVC conduit device box, conduit body, or other conduit termination. Con- shall be permitted to be unsupported where the raceway is duit listed for securing at other than 900 mm (3 ft) shall be not more than 450 mm (18 in.) and remains in unbroken permitted to be installed in accordance with the listing. lengths(without coupling). Such raceway shall terminate in an outlet box, junction box, device box, cabinet, or other (B) Supports. PVC conduit shall be supported as required termination at each end of the raceway. in Table 352.30. Conduit listed for support at spacings other than as shown in Table 352.30 shall be permitted to 352.44 Expansion Fittings. Expansion fittings for PVC be installed in accordance with the listing. Horizontal runs conduit shall be provided to compensate for thermal expan- of PVC conduit supported by openings through framing sion and contraction where the length change, in accordance members at intervals not exceeding those in Table 352.30 with Table 352.44,is expected to be 6 mm(1/4 in.)or greater in and securely fastened within 900 mm (3 ft) of termination a straight run between securely mounted items such as boxes, points shall be permitted. cabinets, elbows, or other conduit terminations. Table 352.30 Support of Rigid Polyvinyl Chloride Conduit 352.46 Bushings. Where a conduit enters a box, fitting, or (PVC) other enclosure, a bushing or adapter shall be provided to protect the wire from abrasion unless the box, fitting, or Maximum Spacing Between enclosure design provides equivalent protection. Conduit Size Supports FPN: See 300.4(G) for the protection of conductors 4 Metric AWG and larger at bushings. Designator Trade Size mm or m ft 352.48 Joints. All joints between lengths of conduit, and 16-27 1/l 9(10 mm 3 between conduit and couplings, fittings, and boxes, shall be 35--53 1 /4-2 1.5 m 5 made by an approved method. 63-78 21/­3 l.8 in 6 91-129 31/:-5 2.1 m 7 155 6 2.5 m 8 352.56 Splices and Taps. Splices and taps shall be made in accordance with 300.15. Table 352.44 Expansion Characteristics of PVC Rigid Nonmetallic Conduit Coefficient of Thermal Expansion = 6.084 x 10-s mm/mm/°C (3.38 x 10'S inJinJ°F) Length Change of Length Change of Temperature PVC Conduit Temperature PVC Conduit Temperature Length Change of PVC Change (°C) (mm/m) Change CF) (inJ100 ft) Change (°F) Conduit (inJ100 Ft) 5 0.30 5 0.20 105 4.26 10 0.61 l0 0.41 110 4.46 15 0.91 15 0.61 115 4.66 20 1.22 20 0.81 120 4.87 25 1.52 25 1.0 1 125 5.07 30 1.83 30 1.22 130 5.27 35 2.13 35 1.42 135 5.48 40 2.43 40 1.62 140 5.68 45 2.74 45 1.83 145 5.88 50 3.04 50 2.43 150 6,08 55 3.35 55 2.23 155 6.29 60 3.65 60 2.43 160 6.49 65 3.95 65 2.64 165 6.69 70 4.26 70 2.84 170 6,90 75 4.56 75 3.04 175 7.10 80 4.87 80 3.24 180 7.30 85 5.17 85 3.45 185 7.50 90 5.48 90 3.65 190 7.71 95 5.78 95 3.85 195 7.91 100 6.08 100 4.06 200 8.11 2008 Edition NATIONAL ELECTRICAL CODE 70,199 352.60 ARTICLE 353—HIGH DENSITY POLYETHYLENE CONDUIT:TYPE HDPE CONDUIT 352.60 Grounding. Where equipment grounding is re- FPN: Refer to Article 352 for Rigid Polyvinyl Chloride quired, a separate equipment grounding conductor shall be Conduit:Type 'PVC and Article 355 for Reinforced They installed in the conduit. mosetting Resin Conduit:Type RTRC. Exception No. 1: As permitted in 250.134(B), Exception 353.2 Definition. No. 2,for do circuits and 250.134(B), Exception No. 1,for High Density Polyethylene (HDPE) Conduit. A nonme- separately run equipment grounding conductors. tallic raceway of circular cross section, with associated Exception No. 2: Where the grounded conductor is used to couplings, connectors, and fittings for the installation of ground equipment as permitted in 250.142. electrical conductors. III. Construction Specifications 353.6 Listing Requirements. HDPE conduit and associ- ated fittings shall be listed. 352.100 Construction. PVC conduit shall be made of rigid(nonplasticized) polyvinyl chloride(PVC). PVC con- 11. Installation duit and fittings shall be composed of suitable nonmetallic material that is resistant to moisture and chemical atmo- 353.10 Uses Permitted.The use of HDPE conduit shall be spheres. For use aboveground, it shall also be flame retar- permitted under the following conditions: dant,resistant to impact and crushing, resistant to distortion (1) In discrete lengths or in continuous lengths from a reel from heat under conditions likely to be encountered in ser- vice, and resistant to low temperature and sunlight effects. (2} In locations subject to severe corrosive influences as For use underground, the material shall be acceptably resis- covered in and where subject to chemicals for tant to moisture and corrosive agents and shall be of suffi- which the conduit is listed cient strength to withstand abuse, such as by impact and (3) In cinder fill crushing, in handling and during installation. Where in- (4) In direct burial installations in earth or concrete tended for direct burial, without encasement in concrete, FPN to (4): Refer to 300.5 and 300.50 for underground the material shall also be capable of withstanding continued installations. loading that is likely to be encountered after installation. (5) Above ground, except as prohibited in 353.12, where encased in not less than 50 man(2 in.) of concrete. 352.120 Marking. Each length of PVC conduit shall be clearly and durably marked at least every 3 m (10 ft) as 353.12 Uses Not Permitted. HDPE conduit shall not be required in the first sentence of 110.21.The type of material used under the following conditions: shall also be included in the marking unless it is visually (1) Where exposed identifiable. For conduit recognized for use aboveground, these markings shall be permanent. For conduit limited to (2) Within a building underground use only, these markings shall be sufficiently (3) In any hazardous(classified)location,except as permit- durable to remain legible until the material is installed. ted by other articles in this Code Conduit shall be permitted to be surface marked to indicate (4) Where subject to ambient temperatures in excess of special characteristics of the material. 50°C (122°F) unless listed otherwise FPN: Examples of these markings include but are not lim- (5) For conductors or cables operating at a temperature ited to "limited smoke" and "sunlight resistant." higher than the HDPE conduit listed operating tem- perature rating Exception: Conductors or cables rated at a temperature higher than the HDPE conduit listed temperature rating ARTICLE 353 shall be permitted to be installed in HDPE conduit, pro- vided they are not operated at a temperature higher than High Density Polyethylene Conduit: the HDPE conduit listed temperature rating. ape HDPE Conduit 353.20 Size. 1. General (A) Minimum. HDPE conduit smaller than metric desig- 353.1 Scope. This article covers the use, installation, and nator 16 (trade size I/z) shall not be used. construction specifications for high density polyethylene (B) Maximum. HDPE conduit larger than metric designa- (HDPE) conduit and associated fittings. for 155 (trade size 6) shall not be used. 70--200 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 354—NONMETALLIC UNDERGROUND CONDUIT WITH CONDUCTORS:TYPE NUCC 354.10 FPN: The trade sizes and metric designators are for iden- III. Construction Specifications tilication purposes only and do not relate to actual dimen- sions. See 3tx1.1(C). 353.100 Construction. HDPE conduit shall be composed of high density polyethylene that is resistant to moisture 353.22 Number of Conductors. The number of conduc- and chemical atmospheres. The material shall be resistant tors shall not exceed that permitted by the percentage fill to moisture and corrosive agents and shall be of sufficient specified in Table 1, Chapter 9. strength to withstand abuse, such as by impact and crush- Cables shall be permitted to be installed where such use ing, in handling and during installation. Where intended for is not prohibited by the respective cable articles. The num- direct burial, without encasement in concrete, the material ber of cables shall not exceed the allowable percentage fill shall also be capable of withstanding continued loading that specified in Table 1, Chapter 9. is likely to he encountered after installation. 353.24 Bends—How Made. Bends shall be so made that 353.120 Marking, Each length of HDPE shall be clearly the conduit will not be damaged and the internal diameter and durably marked at least every 3 m (10 ft)as required in of the conduit will not be effectively reduced. Bends shall 110.21. The type of material shall also be included in the be permitted to be made manually without auxiliary equip- marking. ment, and the radius of the curve to the centerline of such bends shall not be less than shown in Table 354.24. 353.26 Bends—Number in One Run.There shall not be ARTICLE 354 more than the equivalent of four quarter bends(360 degrees Nonmetallic Underground Conduit with total) between pull points, for example, conduit bodies and boxes. Conductors: Type NUCC 353.28 Trimming. All cut ends shall be trimmed inside I. General and outside to remove rough edges. 354.1 Scope. This article covers the use, installation, and 353.46 Bushings. Where a conduit enters a box, fitting, or construction specifications for nonmetallic underground other enclosure, a bushing or adapter shall be provided to conduit with conductors (NUCC). protect the wire from abrasion unless the box, fitting, or enclosure design provides equivalent protection. 354.2 Definition. FPN: See 300.4(G) for the protection of conductors 4 Nonmetallic Underground Conduit with Conductors AWG and larger at bushings. (NUCC).A factory assembly of conductors or cables inside a nonmetallic, smooth wall conduit with a circular cross 353.48 Joints. All joints between lengths of conduit, and section. between conduit and couplings, fittings, and boxes, shall be made by an approved method. 354.6 Listing Requirements. NUCC and associated fit- tings shall be listed. FPN: HDPE conduit can be joined using either heat fu- sion,electrofusion, or mechanical fittings. 11I. Installation 353.56 Splices and Taps. Splices and taps shall be made 354.10 Uses Permitted. The use of NUCC and fittings in accordance with 300.15. shall be permitted in the following: (1) For direct burial underground installation (For mini- 353.60 Grounding. Where equipment grounding is re- mum cover requirements, see Table 300.5 and Table quired, a separate equipment grounding conductor shall be 300.50 under Rigid Nonmetallic Conduit.) installed in the conduit. (2) Encased or embedded in concrete Exception No. 1: The equipment grounding conductor (3) In cinder fill shall he permitted to he run separately from the conduit (4) In underground locations subject to severe corrosive where used for grounding do circuits as permitted in influences as covered in 300.6 and where subject to 250.134, Exception No. 2. chemicals for which the assembly is specifically ap- E.xception No. 2: The equipment grounding conductor proved shall not be required where the grounded conductor is used (5) Aboveground, except as prohibited in 354.12, where to ground equipment as permitted in 250.142. encased in not less than 50 mm (2 in.) of concrete. 2008 Edition NATIONAL ELECTRICAL CODE 70-201 354.12 ARTICLE 354—NONMETALLIC UNDERGROUND CONDUIT WITH CONDUCTORS:TYPE NUCC 354.12 Uses Not Permitted. NUCC shall not be used in insulation or jacket. All conduit ends shall be trimmed in- the following: side and out to remove rough edges. (1) In exposed locations (2) Inside buildings 354.46 Bushings. Where the NUCC enters a box, fitting, or other enclosure, a bushing or adapter shall be provided Exception: The conductor or the cable portion of the assem- to protect the conductor or cable from abrasion unless the blr where suitable, shall be permitted to extend within the design of the box, fitting, or enclosure provides equivalent building for termination purposes in accordance with 300.3. protection. (3) In tiny hazardous(classified)location,except as permit- FPN: See 300.4(G) for the protection of conductors size 4 ted by other articles of this Code AWG or larger. 354.20 Size. 354.48 Joints. All joints between conduit, fittings, and (A) Minimum. NUCC smaller than metric designator 16 boxes shall be made by an approved method. (trade size 1/2) shall not be used. 354.50 Conductor Terminations. All terminations be- (B) Maximum. NUCC larger than metric designator 103 tween the conductors or cables and equipment shall be (trade size 4) shall not be used. made by an approved method for that type of conductor or FPN: See 300.1(C) for the metric designators and trade cable. Sizes.These are for identification purposes only and do not relate to actual dimensions. 354.56 Splices and Taps. Splices and taps shall be made in junction boxes or other enclosures. 354.22 Number of Conductors. The number of conduc- tors or cables shall not exceed that permitted by the per- 354.60 Grounding. Where equipment grounding is re- centage fill in Table 1, Chapter 9, quired, an assembly containing a separate equipment 354.24 Bends — How Made. Bends shall be manually grounding conductor shall be used. made so that the conduit will not be damaged and the in- ternal diameter of the conduit will not be effectively re- III. Construction Specifications duced, The radius of the curve of the centerline of such 354.100 Construction. bends shall not be less than shown in Table 354.24. (A) General. NUCC is an assembly that is provided in Table 354.24 Minimum Bending Radius for Nonmetallic continuous lengths shipped in a coil, reel, or carton. Underground Conduit with Conductors (NUCC) (B) Nonmetallic Underground Conduit.The nonmetallic Minimum Bending underground conduit shall be listed and composed of a ma- Conduit Size Radius terial that is resistant to moisture and corrosive agents. It Metric shall also be capable of being supplied on reels without Designator Trade Size mm in. damage or distortion and shall be of sufficient strength to 16 300 12 withstand abuse, such as impact or crushing, in handling 21 1 V2 z 250 10 and during installation without damage to conduit or con- ;/a 27 1 350 1.4 ductors. 35 11/4 450 18 41 11/2 500 20 (C) Conductors and Cables. Conductors and cables used 53 2 650 26 in NUCC shall be listed and shall comply with 310.8(C). 63 2'/2 900 36 Conductors of different systems shall be installed in accor- 78 3 1200 48 dance with 300.3(C). 103 4 1500 60 (D) Conductor Fill.The maximum number of conductors 354.26 Bends—Number in One Run.There shall not be or cables in NUCC shall not exceed that permitted by the more than the equivalent of four quarter bends(360 degrees percentage fill in Table 1, Chapter 9. total) between termination points. 354.120 Marking. NUCC shall be clearly and durably 354.28 'IYimming. For termination, the conduit shall be marked at least every 3.05 m (10 ft) as required by 110.21, trimmed away from the conductors or cables using an ap- The type of conduit material shall also be included in the proved method that will not damage the conductor or cable marking. 70-202 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 355—REINFORCED THERMOSETTING RESIN CONDUIT:TYPE RTRC 355.20 Identification of conductors or cables used in the assem- (E) Dry and Damp Locations. RTRC shall be permitted bly shall be provided on a tag attached to each end of the for use in dry and damp locations not prohibited by 355.12. assembly or to the side of a reel. Enclosed conductors or cables shall be marked in accordance with 310.11. (F) Exposed.RTRC shall be permitted for exposed work where not subject to physical damage if identified for such use. (G) Underground Installations.For underground installa- ARTICLE 355 tions, see 300.5 and 300.50. Reinforced Thermosetting Resin Conduit: Type RTRC {H} Support of Conduit Bodies, RTRC shall be permitted to support nonmetallic conduit bodies not larger than the largest trade size of an entering raceway. These conduit I. General bodies shall not support luminaires or other equipment and shall not contain devices other than splicing devices as 355.1 Scope. This article cavern the use, installation, and permitted by 110.14(B) and 314.I6(C)(2). construction specification for reinforced thermosetting resin conduit (RTRC) and associated fittings. 355.12 Uses Not Permitted. RTRC shall not be used un- PPN: Refer to Article 352 for Rigid Polyvinyl Chloride der the following conditions. Conduit: Type PVC, and Article 353 for High Density Polyethylene Conduit: Type HDPE. (A) Hazardous (Classified) Locations. (1) In any hazardous (classified)location,except as permit- 355.2 Definition. led by other articles in this Code Reinforced Thermosetting Resin Conduit (RTRC). A (2) In Class I, Division 2 locations, except as permitted in rigid nonmetallic conduit (RNC) of circular cross section, 501.10(B)(3) with integral or associated couplings, connectors, and fit- tings for the installation of electrical conductors and cables. (B) Support of Luminaires.For the support of luminaires or other equipment not described in 355.10(H). 355.6 Listing Requirements. RTRC, factory elbows, and associated fittings shall be listed. (C) Physical Damage. Where subject to physical damage unless identified for such use. II. Installation (D) Ambient Temperatures. Where subject to ambient temperatures in excess of 50°C (122°F) unless listed 355.10 Uses Permitted.The use of RTRC shall be permit- otherwise. ted in accordance with 355.10(A) through (H). (E) Insulation Temperature Limitations. For conductors (A) Concealed. RTRC shall be permitted in walls, floors, or cables operating at a temperature higher than the RTRC and ceilings. listed operating temperature rating. (B) Corrosive Influences. RTRC shall be permitted in lo- Exception: Conductors or cables rated at a temperature cations subject to severe corrosive influences as covered in higher than the RTRC listed temperature rating shall be 300.6 and where subject to chemicals for which the mate- permitted to be installed in RTRC, provided they are not rials are specifically approved. operated at a temperature higher than the RTRC listed (C) Cinders. RTRC shall be permitted in cinder fill. temperature rating, (F) Theaters and Similar Locations.In theaters and sirni- (D) Wet Locations. RTRC shall be permitted in portions far locations, except as provided in 518.4 and 520.5. of dairies, laundries, canneries, or other wet locations, and in locations where walls are frequently washed, the entire 355.20 Size. conduit system, including boxes and fittings used therewith, shall be installed and equipped so as to prevent water from (A) Minimum. RTRC smaller than metric designator 16 entering the conduit.All supports, bolts, straps,screws, and (trade size '/z) shall not be used. so forth, shall be of corrosion-resistant materials or be pro- tected against corrosion by approved corrosion-resistant (B) Maximum. RTRC larger than metric designator 155 materials. (trade size 6) shall not be used. 2008 Edition NAMNAL ELEC-rRICAL CODE 70-203 355.22 ARTICLE 355--REINFORCED THERMOSETTING RESIN CONDUIT:TYPE RTRC FPN: The trade sizes and metric designators are for iden- Table 355.34 Support of Reinforced Thermosetting Resin tification purposes only and do not relate to actual dimen- I Conduit(RTRC) sions. See 300.1(C). Maximum Spacing 355.22 Number of Conductors. The number of conduc- Conduit Size Between Supports tors shall not exceed that permitted by the percentage fill specified in Table I, Chapter 9. Cables shall be permitted to Metric be installed where such use is not prohibited by the respec- Designator Trade Size mm or m ft tive cable articles. The number of cables shall not exceed 16-27 '!z-1 900 mm 3 the allowable percentage fill specified in Table 1,Chapter 9. 35-53 11/4-2 1.5 m 5 63-78 214-3 1.8 m 6 355.24 Bends —How Made. Bends shall be so made that 91-129 31/2-5 2.1 m 7 the conduit will not be damaged and the internal diameter 155 6 2.5 m 8 of the conduit will not be effectively reduced. Field bends shall be made only with bending equipment identified for the contraction where the length change, in accordance with purpose. The radius of the curve to the centerline of such Table 355.44, is expected to be 6 mm (1!4 in.) or greater in bends shall not be less than shown in Table 2, Chapter 9. a straight run between securely mounted items such as boxes, cabinets, elbows, or other conduit terminations. 355.26 Bends —Number in One Run. There shall not be more than the equivalent of four quarter bends(360 degrees 355.46 Bushings.Where a conduit enters a box, fitting, or total) between pull points, for example, conduit bodies and other enclosure, a bushing or adapter shall be provided to boxes. protect the wire from abrasion unless the box, fitting, or 355.28 Trimming. All cut ends shall be trimmed inside enclosure design provides equivalent protection. and outside to remove rough edges. FPN: See 300.4(G) for the protection of conductors 4 AWG and larger at bushings. 355.30 Securing and Supporting.RTRC shall be installed as a complete system in accordance with 300.18 and shall 355.48 Joints. All joints between lengths of conduit, and be securely fastened in place and supported in accordance between conduit and couplings, fitting, and boxes, shall be with 355.30(A) and (B) or permitted to be unsupported in made by an approved method. accordance with 355.30(C). 355.56 Splices and Taps. Splices and taps shall be made (A) Securely Fastened. RTRC shall be securely fastened in accordance with 300.15. within 900 mm (3 ft) of each outlet box, junction box, device box, conduit body, or other conduit termination. 355.60 Grounding. Where equipment grounding is re- Conduit listed for securing at other than 900 mm(3 ft)shall quired, a separate equipment grounding conductor shall be be permitted to be installed in accordance with the listing. installed in the conduit. (B) Supports. RTRC shall be supported as required in F-rception No. 1: As permitted in 250.134(B), Exception Table 355.30. Conduit listed for support at spacing other No. 2,for do circuits and 250.134(B), Exception No. 1,for than as shown in Table 355.30 shall be permitted to be separately run equipment grounding conductors. installed in accordance with the listing. Horizontal runs of Exception No. 2: Where the grounded conductor is used to RTRC supported by openings through framing members at ground equipment as permitted in 250.142. intervals not exceeding those in Table 355.30 and securely fastened within 900 mm(3 ft)of termination points shall be permitted. III. Construction Specifications (C) Unsupported Raceways.Where oversized, concentric 355.100 Construction. RTRC and fittings shall be com- or eccentric knockouts are not encountered, Type RTRC posed of suitable nonmetallic material that is resistant to shall be permitted to be unsupported where the raceway is moisture and chemical atmospheres. For use aboveground, not more than 450 mm (18 in.) and remains in unbroken it shall also be flame retardant, resistant to impact and lengths (without coupling). Such raceways shall terminate crushing, resistant to distortion from heat under conditions in an outlet box, device box,cabinet,or other termination at likely to be encountered in service, and resistant to low each end of the raceway. temperature and sunlight effects. For use underground, the material shall be acceptably resistant to moisture and cor- 355.44 Expansion Fittings. Expansion fittings for RTRC rosive agents and shall be of sufficient strength to withstand shall be provided to compensate for thermal expansion and abuse, such as by impact and crushing, in handling and 70_204 NATIONAL ELECTRICAL CODE 2W8 Edition ARTICLE 356-LIQUIDTIGHT FLEXIBLE NONMETALLIC CONDUIT:'TYPE LFNC 356.2 Table 355.44 Expansion Characteristics of Reinforced Thermosetting Resin Conduit (RTRC) Coefficient of Thermal Expansion =2.7 x 10-; mudmm/°C (I.5 x 10-` in./inJ°F) Length Change of Length Change of Temperature RTRC Conduit Temperature RTRC Conduit Temperature Length Change of RTRC Change (°C) (mm/m) Change (°F) (inJ100 ft) Change (°F) Conduit(inJ100 ft) 5 0.14 5 0.09 105 1,89 10 0.27 10 0.18 110 1.98 15 0.41 15 0.27 115 2.07 20 0.54 20 0.36 120 2.16 25 0.68 25 0.45 125 2.25 30 0.81 30 0.54 130 2.34 35 0.95 35 0.63 135 2,43 40 1.08 40 0.72 140 2.52 45 1.22 45 0.81 145 2.61 50 1.35 50 0.90 150 2.70 55 1.49 55 0.99 155 2.79 60 1.62 60 1.08 160 2.88 65 1.76 65 1.17 165 2.97 70 1.89 70 1.26 170 3.06 75 2.03 75 1.35 175 3.15 80 116 80 1.44 180 3.24 85 2.30 85 1.53 185 3.33 90 2.43 90 1.62 190 3.42 95 2.57 95 1.71 195 3.51 100 2.70 100 1.80 200 3.60 during installation. Where intended for direct burial, with- out encasement in concrete, the material shall also be ca- ARTICLE 356 pable of withstanding continued loading that is likely to be Liquildtight Flexible Nonmetallic encountered after installation. Conduit: Type LFNC 355.120 Marking. Each length of RTRC shall be clearly and durably marked at least every 3 m(10 ft) as required in I. General the first sentence of 110.21. The type of material shall also 356.1 Scope. This article covers the use, installation, and he included in the marking unless it is visually identifiable. construction specifications for liquidtight flexible nomne- For conduit recognized for use aboveground, these mark- tallic conduit (LFNC) and associated fittings, ings shall be permanent. For conduit limited to under- ground use only, these markings shall be sufficiently du- rable to remain legible until the material is installed. Liquidtight Flexible Nonmetallic Conduit(LFNC).A race- Conduit shall be permitted to be surface marked to indicate way of circular cross section of various types as follows: special characteristics of the material. (1) A smooth seamless inner core and cover bonded to- gether and having one or more reinforcement layers iced Examples these markings include but are not lim-ted to "limited smoke" between the core and covers, designated as Type oke" and "sunlight resistant." LFNC-A (2) A smooth inner surface with integral reinforcement within the conduit wall, designated as Type LFNC-B (3) A corrugated internal and external surface without in- tegral reinforcement within the conduit wall, desig- nated as LFNC-C LFNC is flame resistant and with fittings and is ap- proved for the installation of electrical conductors. FPN: F'NMC is an alternative designation for LFNC. 2008 Edition NATIONAL FLECTRICAL CODE 7(--205 356.6 ARTICLE 356---LIQUIDTIGHT FLEXIBLE NONMETALLIC CONDUIT: TYPE LFNC 356.6 Listing Requirements. LFNC and associated fit- (2) In lengths not exceeding 1.8 m(6 ft ) as part of a listed tings shall be listed. assembly for tap connections to luminaires as required in 410.117(C), or for utilization equipment I1. Installation (B) Maximum. LFNC larger than metric designator 103 356.10 Uses Permitted. LFNC shall be permitted to be (Fade size 4) shall not be used. used in exposed or concealed locations for the following FPN: See 300.1(C) for the metric designators and trade purposes: sizes.These are for identification purposes only and do not relate to actual dimensions. FPM: Extreme cold may cause some types of nonmetallic conduits to become brittle and therefore more susceptible to 356,22 Number of Conductors. The number of conduc- damage from physical contact. tors shall not exceed that permitted by the percentage fill (1) Where flexibility is required for installation, operation, specified in Table 1, Chapter 9. or maintenance. Cables shall be permitted to be installed where such use (2) Where protection of the contained conductors is re- is not prohibited by the respective cable articles. The num- quired from vapors, liquids, or solids. ber of cables shall not exceed the allowable percentage fill (3) For outdoor locations where listed and marked as suit- specified in Table 1, Chapter 9, able for the purpose. 356.24 Bends—How Made.Bends in conduit shall be so (4) For direct burial where listed and marked for the pur- made that the conduit is not damaged and the internal" di- pose. ameter of the conduit is not effectively reduced.Bends shall (5) Type LFNC-B shall be permitted to be installed in be permitted to be made manually without auxiliary equip- lengths longer than 1.8 m (6 ft) where secured in ac- ment. The radius of the curve to the centerline of any bend cordance with 356.30. shall not be less than shown in Table 2,Chapter 9 using the (6) Type LFNC-B as a listed manufactured prewired as- column "Other Bends." sembly, metric designator 16 through 27 (trade size '/z through I) conduit. 356.26 Bends—Number in One Run.There shall not be more than the equivalent of four quarter bends(360 degrees (7) For encasement in concrete where listed for direct total) between pull points, for example, conduit bodies and burial and installed in compliance with 356.42. boxes. 356.12 Uses Not Permitted. LFNC shall not be used as follows: 356.28 ''Ir'imming. All cut ends of conduit shall be trimmed inside and outside to remove rough edges. (1) Where subject to physical damage (2) Where any combination of ambient and conductor tem- 356.30 Securing and Supporting. Type LFNC-B shall be peratures is in excess of that for which the LFNC is securely fastened and supported in accordance with one of approved the following: (3) In lengths longer than 1.8 m (6 ft), except as permitted (1) Where installed in lengths exceeding 1.8 m (6 ft), the by 356.10(5) or where a longer length is approved as conduit shalt be securely fastened at intervals not ex- essential for a required degree of flexibility ceeding 900 mm (3 ft) and within 300 mm (12 in.) on (4) Where the operating voltage of the contained conduc- each side of every outlet box,junction box, cabinet, or tors is in excess of 600 volts, nominal, except as per- fitting. mitted in 600.32(A) (2) Securing or supporting of the conduit shall not be re- (5) In any hazardous(classified)location,except as permit- quired where it is fished, installed in lengths not ex- ted by other articles in this Code ceeding 900 mm (3 ft) at terminals where flexibility is required, or installed in lengths not exceeding 1.8 m 356.20 Size. (6 ft) from a luminaire terminal connection for tap con- ductors to luminaires permitted in 410.117(C). (A) Minimum. LFNC smaller than metric designator 16 (3) Horizontal runs of LFNC supported by openings (trade size 1/2) shall not be used unless permitted in through framing members at intervals not exceeding 356.20(A)(1) or (A)(2) for metric designator 12 (trade 900 mm (3 ft) and securely fastened within 300 mm size ;/a). (12 in.) of termination points shall be permitted. (1) For enclosing the leads of motors as permitted in (4) Securing or supporting of LFNC-B shall not be re- 430.245(B) quired where installed in lengths not exceeding 1.8 m 70-206 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 358--ELECTRICAL.METALLIC TUBING:TYPE EMT 358.20 (6 ft) frorn the last point where the raceway is securely physical protection and routing of conductors and cables fastened for connections within an accessible ceiling to and for use as an equipment grounding conductor when luminaires) or other equipment. installed utilizing appropriate fittings. EMT is generally made of steel (ferrous) with protective coatings or alumi- 356.42 Couplings and Connectors.Only fittings listed for num (nonferrous). use with LFNC shall be used.Angle connectors shall not be used for concealed raceway installations. Straight LFNC 358,6 Listing Requirements. EMT, factory elbows, and fittings are permitted for direct burial or encasement in associated fittings shall be listed. concrete. 356,56 Splices and Taps. Splices and taps shall be made II. Installation in accordance with 300.15. 358.10 Uses Permitted. 356.60 Grounding and Bonding. Where used to connect (A) Exposed and Concealed. The use of EMT shall be equipment where flexibility is required, an equipment permitted for both exposed and concealed work, grounding conductor shall be installed. Where required or installed, equipment grounding con- (B) Corrosion Protection.Ferrous or nonferrous EMT,el- ductors shall be installed in accordance with 250.134(B). bows, couplings, and fittings shall be permitted to be in- Where required or installed, equipment bonding jump- stalled in concrete, in direct contact with the earth, or in areas ers shall be installed in accordance with 250.102. subject to severe corrosive influences where protected by cor- rosion protection and judged suitable for the condition. III. Construction Specifications (C) Wet Locations. All supports,bolts, straps,screws, and 356.100 Construction. LFNC-13 as a prewired manufac- so forth shall be of corrosion-resistant materials or pro- tured assembly shall be provided in continuous lengths ca- tected against corrosion by corrosion-resistant materials. pable of being shipped in a coil, reel, or carton without damage. FPN: See 300.6 for protection against corrosion. 356.120 Marking. LFNC shall be marked at least every 358.12 Uses Not Permitted. EMT shall not be used under 600 mm (2 ft) in accordance with 110.21. The marking the following conditions: shall include a type designation in accordance with 356.2 (1) Where, during installation or afterward, it will be sub- and the trade size. Conduit that is intended for outdoor use ject to severe physical damage. or direct burial shall be marked. (2) Where protected from corrosion solely by enamel. The type, size, and quantity of conductors used in (3) In cinder concrete or cinder fill where subject to per- prewired manufactured assemblies shall be identified by manent moisture unless protected on all sides by a means of a printed tag or label attached to each end of the layer of noncinder concrete at least 50 mm (2 in.)thick manufactured assembly and either the carton, coil, or reel, or unless the tubing is at least 450 mm (18 in.) under The enclosed conductors shall be marked in accordance the fill, with 310.11. (4) In any hazardous (classified) location except as permit- ted by other articles in this Code. (5) For the support of luminaires or other equipment ex- cept conduit bodies no larger than the largest trade size ARTICLE 358 of the tubing. Electrical Metallic Thbing: Type EMT (6) Where practicable, dissimilar metals in contact any- where in the system shall be avoided to eliminate the I. General possibility of galvanic action. 358.1 Scope. This article covers the use, installation, and Exception: Aluminum fittings and enclosures shall be per- construction specifications for electrical metallic tubing nutted to be used with steel EMT where not subject to (EMT) and associated fittings. severe corrosive influences. 358.2 Definition. 358.20 Size. Electrical Metallic Tubing (EMT). An unthreaded thin- (A) Minimum. EMT smaller than metric designator 16 wall raceway of circular cross section designed for the (trade size 11) shall not be used. 2008 Edition NATIONAL ELECTRICAL CODF 70-207 358.22 ARTICLE 360—FLEXIBLE METALLIC TUBING:TYPE FMT Exception: For enclosing the leads of motors as permitted ticable, unbroken lengths (without coupling) of EMT shall in 430.245(B). be permitted to be fished. (B) Maximum. The maximum size of EMT shall be met- (B) Supports.Horizontal runs of EMT supported by open- ric designator 103 (trade size 4). ings through framing members at intervals not greater than 3 m (10 ft) and securely fastened within 900 mm (3 ft) of FPN: See 300.1(0) for the metric designators and trade termination points Shall be permitted. sizes.These are for identification purposes only and do not relate to actual dimensions. (C) Unsupported Raceways.Where oversized,concentric 358.22 Number of Conductors. The number of conduc- or eccentric knockouts are not encountered, 'Type EMT tors shall not exceed that permitted by the percentage fill Shall be permitted to be unsupported where the raceway is specified in Table 1, Chapter 9. not more than 450 mm (18 in.) and remains in unbroken Cables shall be permitted to be installed where such use lengths (without coupling), Such raceways shall terminate is not prohibited by the respective cable articles. The num- in an outlet box,device box.,cabinet,or other term. uatioa at ber of cables shall not exceed the allowable percentage fill each end of the raceway. specified in Table 1, Chapter 9. 358.42 Couplings and Connectors.Couplings and connec- tors used with EMT shall be made up tight. Where buried in 358.24 Bends—How Made. Bends shall be made so that masonry or concrete, they shall be concretetight type. Where the tubing is not damaged and the internal diameter of the installed in wet locations, they shall comply with 314.15. tubing is not effectively reduced.The radius of the curve of any field bend to the centerline of the tubing shall not be 358,56 Splices and Taps. Splices and taps shall be made less than shown in Table 2, Chapter 9 for one-shot and full in accordance with 300.15. shoe benders. 358.60 Grounding. EMT shall be permitted as an equip- 358.26 Bends—Number in One Run.There shall not be ment grounding conductor. more than the equivalent of four quarter bends(360 degrees total) between pull points, for example, conduit bodies and III. Construction Specifications boxes. 358.100 Construction. Factory-threaded integral cou- 358.28 Reaming and Threading. plings shall be permitted. Where EMT with a threaded in- (A) Reaming. All cut ends of EMT shall be reamed or tegral coupling is used, threads for both the tubing and otherwise finished to remove rough edges. coupling shall be factory-made. The coupling and EMT threads shall be designed so as to prevent bending of the (B) Threading. EMT shall not be threaded. tubing at any part of the thread. Exception: EMT with factory threaded integral couplings 358.120 Marking. EMT shall be clearly and durably complying with 358.100. marked at least every 3 m (10 ft) as required in the first 358.30 Securing and Supporting. EMT shall be installed sentence of 110.21. as a complete system in accordance with 300.18 and shall be securely fastened in place and supported in accordance with 358.30(A) and (B) or permitted to be unsupported in accordance with 358.30(0). ARTICLE 360 (A) Securely Fastened. EMT shall be securely fastened in Flexible Metallic Tabing: Type FMT place at least every 3 m (10 ft). In addition, each EMT run between termination points shall he securely fastened within I. General 900 mm (3 ft) of each outlet box,junction box, device box, 360.1 Scope. This article covers the use, installation, and cabinet, conduit body, or other tubing termination. construction specifications for flexible metallic tubing Exception No. 1: Fastening of unbroken lengths shall be (FMT) and associated fittings. permitted to be increased to a distance of 1.5 m(5 ft)where structural members do not readily permit fastening within 360.2 Definition. 900 mm (3 ft). Flexible Metallic Tubing (FMT). A raceway that is circu- Erception No. 2: For concealed work in finished buildings lar in cross section, flexible, metallic, and liquidtight with- or prefinished wall panels where such securing is imprac- out a nonmetallic jacket. 7208 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 360—FLEXIBLE METALLIC TUBING:TYPE FMT 360.120 360.6 Listing Requirements. FMT and associated fittings ber of cables shall not exceed the allowable percentage fill shall be listed. specified in Table 1, Chapter 9. (B) FMT — Metric Designator 12 (Trade Size '/s). The 1I. Installation number of conductors in metric designator 12 (trade size 360.10 Uses Permitted.FMT shall be permitted to be used '/x) shall not exceed that permitted in Table 348.22. for branch circuits as follows: 360.24 Bends. (1) In dry locations (2) Where concealed (A) Infrequent Flexing Use. Where FMT may be infre- quently flexed in service after installation, the radii of (3) In accessible locations bends measured to the inside of the bend shall not be less (4) For system voltages of 1000 volts maximum than specified in Table 360.24(A). 360.12 Uses Not Permitted. FMT shall not be used as Table 360.24(A) Minimum Radii for Flexing Use follows: (1) In hoistways Minimum Radii (2) In storage battery rooms Metric for Flexing Use (3) In hazardous (classified) locations unless otherwise Designator Trade Size mm in. permitted under other articles in this Code 12 '/K 254.0 10 (4) Underground for direct earth burial, or embedded in 16 '12 317,5 121/2 poured concrete or aggregate 21 314 444.5 171/2 (5) Where subject to physical damage (6) In lengths over 1.8 m (6 ft) (B) Fixed Bends. Where FMT is bent for installation pur- poses and is not flexed or bent as required by use after 360.20 Size. installation, the radii of bends measured to the inside of the (A) Minimum. FMT smaller than metric designator 16 bend shall not be less than specified in Table 360.24(8). (trade size 1/2) shall not be used. Table 360.24(B) Minimum Radii for Fixed Bends Exception No. 1: FMT of metric designator 12 (trade size /H) shall be permitted to be installed in accordance with Minimum Radii 300.22(B) and(C). Metric for Fixed Bends Exception No. 2: FMT of metric designator 12 (trade size Designator Trade Size mm in. ?/v)shall be permitted in lengths not in excess of 1.S m (6 ft) as part of a listed assembly or for luminaires. See 12 ;/K 88.6 3y2 16 1/2 101.6 4 410.117(C). 21 %4 127.0 5 (B) Maximum.The maximum size of FMT shall be metric designator 21 (trade size 3/4). 360.40 Boxes and Fittings. Fittings shall effectively close FPN: See 300.1(C) for the metric designators and trade any openings in the connection. sizes.These are for identification purposes only and do not 360.56 Splices and Taps. Splices and taps shall be made relate to actual dimensions. in accordance with 300.15. 360.22 Number of Conductors. 360.60 Grounding. FMT shall be permitted as an equip- (A) FMT—Metric Designators 16 and 21 (Trade Sizes ment grounding conductor where installed in accordance 1/2 and-1/4).The number of conductors in metric designators with 250.118(7). 16 (trade size I/2) and 21 (trade size '/4) shall not exceed that permitted by the percentage fill specified in Table 1, III. Construction Specifications Chapter 9. Cables shall be permitted to be installed where such use 360.120 Marking. FMT shall be marked according to is not prohibited by the respective cable articles. The num- 110.21. 2008 Edition NATIONAL ELECTRICAL CODE 70-209 362.1 ARTICLE 362—ELECTRICAL NONMETALLIC TUBING:TYPE ENT FPN: A finish rating is established for assemblies contain- ARTICLE 362 ing combustible (wood) supports. The finish rating is de- fined as the time at which the wood stud or wood joist Electrical Nonmetallic `jbing: reaches an average temperature rise of 121°C(250°F)or an Type ENT individual temperature of 163°C (325°F) as measured on the plane of the wood nearest the fire.A finish rating is not intended to represent a rating for a membrane ceiling. I. General (3) In locations subject to severe corrosive influences as 362.1 Scope. This article covers the use, installation, and covered in 300.6 and where subject to chemicals for construction specifications for electrical nonmetallic tubing which the materials are specifically approved. (ENT) and associated fittings. (4) In concealed,dry, and damp locations not prohibited by 362.12. 362.2 Definition. (5) Above suspended ceilings where the suspended ceil- ings provide a thermal barrier of material that has at Electrical Nonmetallic Tubing (ENT). A nonmetallic, pli- least a 15-minute finish rating as identified in listings of able, corrugated raceway of circular cross section with in- fire-rated assemblies, except as permitted in tegral or associated couplings, connectors, and fittings for 362.10(1)(a). the installation of electrical conductors. ENT is composed of a material that is resistant to moisture and chemical Exception to {5}: ENT shall be permitted to be used above atmospheres and is flame retardant, suspended ceilings in buildings exceeding three floors A pliable raceway is a raceway that can be bent by hand above grade where the building is protected throughout by with a reasonable force but without other assistance. a .fire sprinkler system installed in accordance with NFPA 13-2007, Standard for the Installation of Sprinkler 362.6 Listing Requirements. ENT and associated fittings Systems. shall be listed. (6) Encased in poured concrete,or embedded in a concrete stab on grade where ENT is placed on sand or ap- proved screenings, provided fittings identified for this II. Installation purpose are used for connections. 362.10 Uses Permitted.For the purpose of this article, the (7) For wet locations indoors as permitted in this section or first floor of a building shall be that floor that has 50 per- in a concrete slab on or belowgrade, with fittings listed cent or more of the exterior wall surface area level with or for the purpose. above finished grade. One additional level that is the first (g) Metric designator 16 through 27 (trade size t/2 through level and not designed for human habitation and used only 1) as listed manufactured prewired assembly. for vehicle parking, storage, or similar use shall be permit- ted. The use of ENT and fittings shall be permitted in the FPN: Extreme cold may cause some types of nonmetallic conduits to become brittle and therefore more susceptible to following: damage from physical contact. (1) In any building not exceeding three floors above grade as follows: 362.12 Uses Not Permitted. ENT shall not be used in the a. For exposed work, where not prohibited by 362.12 following: b. Concealed within walls, floors, and ceilings (1) In any hazardous (classified) location, except as per- (2) In any building exceeding three floors above grade, mitted by tither anieles in this Code ENT shall be concealed within walls, floors, and ceil- (2) For the support of luminaires and other equipment ings where the walls, floors, and ceilings provide a (3) Where subject to ambient temperatures in excess of thermal barrier of material that has at least a 15-minute 50°C (122°F) unless listed otherwise finish rating as identified in listings of fire-rated assem- (4) For conductors or cables operating at a temperature blies. The 15-minute-finish-rated thermal barrier shall higher than the ENT listed temperature rating be permitted to be used for combustible or noncombus- tible walls, floors, and ceilings. Exception to(4): Conductors or cables rated at a tempera- Exception to (2): Where a fire sprinkler system(s) is in- ture higher than the ENT listed temperature rating shall be stalled in accordance with NFPA 13-2007, Standard for the permitted to be installed in ENT, provided they are not Installation of Sprinkler Systems, on all floors, ENT shall operated at a temperature higher than the ENT listed tem- be pennitted to be used within walls,floors, and ceilings, perature rating. exposed or concealed, in buildings exceeding three floors (5) For direct earth burial abovegrade. (6) Where the voltage is over 600 volts 70_210 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 362 ELECTRICAL NONMETALLIC TUBING:TYPE ENT 362.120 (7) In exposed locations, except as permitted by to lighting luminaires .shall he permitted without being 362.10(1), 362.10(5), and 362.10(7) secured. (8) In theaters and similar locations,except as provided in Exception No. 2: Lengths not exceeding 1.8 in (6 ft)from 518.4 and 520.5 the last point where the rac•ex•m is securely'fastened for (9) Where exposed to the direct rays of the sun, unless connections within an accessible ceiling to lurninaire(s) or identified as sunlight resistant other equipment. (LO) Where subject to physical damage Exception No. 3: For concealed work in finished buildings or prefnished wall panels where such securing is imprac- ticable. unbroken lengths (without coupling) of ENT shall (A) Minimum. ENT smaller than metric designator 16 be permitted to be fished. (trade size 1/2) shall not be used. (B) Supports. Horizontal runs of ENT supported by open- (B) Maximum. ENT larger than metric designator 53 ings in framing members at intervals not exceeding 900 mm (trade size 2) shall not be used. (3 ft) and securely fastened within 900 mm (3 ft) of termina- FPN: See 300.1(C) For the metric designators and trade tion points shall be permitted. sizes.These are For identification purposes only and do not 362.46 Buskins Where a tubing enters a box, fitting, or relate to actual dimensions. g € other enclosure, a bushing or adapter shall be provided to 362.22 Number of Conductors. The number of conduc- protect the wire from abrasion unless the box, fitting, or tors shall not exceed that permitted by the percentage fill in enclosure design provides equivalent protection. Table 1, Chapter 9. FPN: See 300.4(G) for the protection of conductors size 4 Cables shall be permitted to be installed where such use AWG or larger. is not prohibited by the respective cable articles. The num- ber of cables shall not exceed the allowable percentage fill 362.48 Joints. All joints between lengths of tubing and specified in Table 1, Chapter 9. between tubing and couplings, fittings, and boxes shall be 362.24 Bends—How Made. Bends shall be so made that by an approved method, the tubing will not be damaged and the internal diameter of 362.56 Splices and Taps. Splices and taps shall be made the tubing will not be effectively reduced. Bends shall be only in accordance with 300.15. permitted to be made manually without auxiliary equip- ment, and the radius of the curve to the centerline of such FPN: See Article 314 for rules on the installation and use bends shall not be less than shown in Table 2, Chapter 9 of boxes and conduit bodies. using the column "Other Bends." 362.60 Grounding, Where equipment grounding is re- 362.26 Bends—Number in One Run.There shall not be quired, a separate equipment grounding conductor shall be more than the equivalent of four quarter bends(360 degrees installed in the raceway in compliance with Article 250, total) between pull points, for example, conduit bodies and Part VI. boxes. 362.2$ Trimming, All cut ends shall be [rimmed inside II1. Construction Specifications and outside to remove rough edges. 362.100 Construction. ENT shall be made of material that does not exceed the ignitibility, flammability, smoke gen- 362.30 Securing and Supporting. ENT shall be installed eration,and toxicity characteristics of rigid(nonplasticized) as a complete system in accordance with 300.18 and shall polyvinyl chloride. be securely fastened in place and supported in accordance ENT, as a prewired manufactured assembly, shall be with 362.30(A) and (B). provided in continuous lengths capable of being shipped in (A) Securely Fastened. ENT shall be securely fastened at a coil, reel, or carton without damage. intervals not exceeding 900 mm (3 ft). In addition, ENT 362.120 Marking. ENT shall be clearly and durably shall be securely fastened in place within 900 mm (3 ft) of each outlet box, device box,junction box, cabinet,or fitting marked at least every 3 m (10 ft) as required in the first where it terminates. sentence of 110.21. The type of material shall also be in- cluded in the marking, Marking for Iimited smoke shall be Exception No. 1: Lengths riot exceeding a distance of 1.8 m permitted on the tubing that has limited smoke-producing (6 ft)from u luminaire tenninal connection for tap connections characteristics. 2008 Edition NATIONAL ELECTRICAL,CODE 70-211 366.1 ARTICLE 366 AUXILIARY GUTTERS The type, size, and quantity of conductors used in (1) Indoor and Outdoor Use. Sheet metal auxiliary gut- prewired manufactured assemblies shall be identified by ters shall be permitted for indoor and outdoor use. means of a printed tag or label attached to each end of the manufactured assembly and either the carton, coil, or reel. (2) Wet Locations. Sheet metal auxiliary gutters installed in wet locations shall be suitable for such locations. The enclosed conductors shall be marked in accordance with 310.1 L (B) Nonmetallic Auxiliary Gutters. Nonmetallic auxil- iary gutters shall be listed for the maximum ambient tem- perature of the installation and marked for the installed conductor insulation temperature rating. ARTICLE 366 (1) Outdoors. Nonmetallic auxiliary gutters shall be per- Auxiliary Gutters mitted to be installed outdoors where listed and marked as suitable for the purpose. I. General FPN: Extreme cold may cause nonmetallic auxiliary gut- ters to become brittle and therefore more susceptible to 366.1 Scope. This article covers the use, installation, and damage from physical contact. construction requirements of metal auxiliary gutters and (2) Indoors.Nonmetallic auxiliary gutters shall be permit- nonmetallic auxiliary gutters and associated fittings. ted to be installed indoors. 366.2 Definitions. 366.12 Uses Not Permitted.Auxiliary gutters shall not be Metallic Auxiliary Gutter.A sheet metal enclosure used to used under the following conditions: supplement wiring spaces at meter centers,distribution cen- (1) To enclose switches, overcurrent devices, appliances, ters, switchboards, and similar points of wiring systems. or other similar equipment The enclosure has hinged or removable covers for housing (2) To extend a greater distance than 9 m (30 ft) beyond and protecting electrical wires,cable,and busbars.The enclo- the equipment that it supplements Sure is designed for conductors to be laid or set in place after Exception: As permitted in 620.35 for elevators, an auxil- the enclosures have been installed as a complete system. iary gutter shall be permitted to extend a distance greater Nonmetallic Auxiliary Gutter. Aflame retardant, non- than 9 m (30 ft) beyond the equipment it supplements. metallic enclosure used to supplement wiring spaces at FPN: For wireways, see Articles 376 and 378. For meter centers, distribution centers,switchboards,and simi- busways, see Article 368. lar points of wiring systems. The enclosure has hinged or removable covers for housing and protecting electrical 366.22 Number of Conductors. wires, cable, and busbars. The enclosure is designed for (A) Sheet Metal Auxiliary Gutters.The sum of the cross- conductors to be laid or set in place after the enclosures sectional areas of all contained conductors at any cross have been installed as a complete system. section of a sheet metal auxiliary gutter shall not exceed 20 percent of the interior cross-sectional area of the sheet 366.6 Listing Requirements. metal auxiliary gutter.The derating factors in 310.15(B)(2)(a) (A) Outdoors. Nonmetallic auxiliary gutters installed out- shall be applied only where the number of current-carrying doors shall comply with the following: conductors, including neutral conductors classified as current- (1) Be listed as suitable for exposure to sunlight carrying under the provisions of 310.15(B)(4), exceeds 30. (2) Be listed as suitable for use in wet locations Conductors for signaling circuits or controller conductors be- (3) Be listed for maximum ambient temperature of the tween a motor and its starter and used only for starting duty installation shall not be considered as current-carrying conductors. (B) Nonmetallic Auxiliary Gutters. The sum of cross- (B) Indoors. Nonmetallic auxiliary gutters installed in- sectional areas of all contained conductors at any cross doors shall be listed for the maximum ambient temperature section of the nonmetallic auxiliary gutter shall not exceed of the installation. 20 percent of the interior cross-sectional area of the non- metallic auxiliary gutter. II. Installation 366.23 Ampacity of Conductors. 366.10 Uses Permitted. (A) Sheet Metal Auxiliary Gutters.Where the number of (A) Sheet Metal Auxiliary Gutters. current-carrying conductors contained in the sheet metal 70-212 NATIONAL ELEC'MICAL CODE 2008 Edition AR-11CLE 366—AUXILIARY GUTTERS 366.120 auxiliary gutter is 30 or less, the adjustment factors specified the gutter is deflected greater than 30 degrees, dimensions in 310.15(B)(2)(a)shall not apply.The current carried continu- corresponding to one wire per terminal in Table 312.6(A) ously in bare copper bars in sheet metal auxiliary gutters shall shall apply. not exceed 1.55 amperes/mm` (1000 amperes/in.') of cross section of the conductor. For aluminum bars, the current (B) Auxiliary Gutters Used as Pull Boxes. Where insu- carried continuously shall not exceed 1.09 amperes/mm= lated conductors 4 AWG or larger are pulled through an (700 amperes/in.") of cross section of the conductor. auxiliary gutter, the distance between raceway and cable entries enclosing the same conductor shall not be less than (B) Nonmetallic Auxiliary Gutters. The derating factors that required in 314.28(A)(1) for straight pulls and specified in 310.15(B)(2)(a) shall be applicable to the 314.28(A)(2) for angle pulls. current-carrying conductors in the nonmetallic auxiliary gutter. 366.60 Grounding. Metal auxiliary gutters shall be con- nected to an equipment grounding conductor(s), to an 366.30 Securing and Supporting, equipment bonding jumper, or to the grounded conductor (A) Sheet Metal Auxiliary Gutters. Sheet metal auxiliary where permitted or required by 250.92(B)(1) or 250.142. gutters shall be supported throughout their entire length at intervals not exceeding 1.5 m (5 ft). Ill. Construction Specifications (B) Nonmetallic Auxiliary Gutters. Nonmetallic auxil- 366.100 Construction. iary gutters shall be supported at intervals not to exceed 900 mm (3 f) and at each end or joint, unless listed for (A) Electrical and Mechanical Continuity. Gutters shall other support intervals. In no case shall the distance be- be constructed and installed so that adequate electrical and tween supports exceed 3 m (10 ft). mechanical continuity of the complete system is secured. 366.44 Expansion Fittings. Expansion fittings shall be in- (B) Substantial Construction.Gutters shall be of substan- tial construction and shall provide a complete enclosure for stalled where expected length change,due to expansion and the contained conductors. All surfaces, both interior and contraction due to temperature change, is more than h mm exterior, shall be suitably protected from corrosion. Corner {0.25 in.). joints shall be made tight, and where the assembly is held 366.56 Splices and Taps. Splices and taps shall comply together by rivets, bolts, or screws, such fasteners shall be with 366.56(A) through (D), spaced not more than 300 mm (12 in.) apart. (A) Within Gutters. Splices or taps shall be permitted (C) Smooth Rounded Edges. Suitable bushings, shields, within gutters where they are accessible by means of re- or fittings having smooth, rounded edges shall be provided movable covers or doors.The conductors, including splices Where conductors pass between gutters, through partitions, and taps, shall not fill the gutter to more than 75 percent of around bends, between gutters and cabinets or junction its area. boxes, and at other locations where necessary to prevent abrasion of the insulation of the conductors. (B) Bare Conductors. Taps from bare conductors shall leave the gutter opposite their terminal connections, and (D) Covers.Covers shall be securely fastened to the gutter. conductors shall not be brought in contact with uninsulated current-carrying parts of different potential. (E) Clearance of Bare Live Parts. Bare conductors shall be securely and rigidly supported so that the minimum (C) Suitably Identified. All taps shall be suitably identi- clearance between bare current-carrying metal parts of dif- fied at the gutter as to the circuit or equipment that they ferent potential mounted on the same surface will not be supply. less than 50 mm (2 in.), nor less than 25 mm (1 in.) for (D) Overcurrent Protection. Tap connections from con- parts that are held free in the air. A clearance not less than ductors in auxiliary gutters shall be provided with overcur- 25 mm (I in.) shall be secured between bare current- rent protection as required in 240.21. carrying metal parts and any metal surface. Adequate pro- visions shall be made for the expansion and contraction of 366.58 Insulated Conductors. busbars. (A) Deflected Insulated Conductors. Where insulated 366.120 Marking. conductors are deflected within an auxiliary gutter, either at the ends or where conduits, fittings, or other raceways or (A) Outdoors. Nonmetallic auxiliary gutters installed out- cables enter or leave the gutter, or where the direction of doors shall have the following markings: 2008 Edition NATIONAL ELECTRICAL CODE 70-,213 368.1 ARTICLE 368—BUSWAYS (1) Suitable for exposure to sunlight (2) Floors. Floor penetrations shall comply with (a) and(b): (2) Suitable for use in wet locations (a) Busways shall be permitted to be extended vertically (3) Installed conductor insulation temperature rating through dry floors if totally enclosed (unventilated) where passing through and for a minimum distance of 1.8 m (6 ft) (B) Indoors. Nonmetallic auxiliary gutters installed in- above the floor to provide adequate protection from physical doors shall have the following markings: damage. (1) installed conductor insulation temperature rating (b) In other than industrial establishments, where a vertical riser penetrates two or more dry floors, a minimum 100-mm (4-in.) high curb shall be installed around all floor openings for riser busways to prevent liquids from entering ARTICLE 368 the opening. The curb shall be installed within 300 mm (12 in.) of the floor opening. Electrical equipment shall be Busways located so that it will not be damaged by liquids that are retained by the curb. I. General Requirements FPN: See 300.21 for information concerning the spread of fire or products of combustion. 368.1 Scope. This article covers service-entrance, feeder, and branch-circuit busways and associated fittings. 368.12 Uses Not Permitted. 368.2 Definition. (A) Physical Damage. Busways shall not be installed where subject to severe physical damage or corrosive vapors. Busway. A grounded metal enclosure containing factory- mounted, bare or insulated conductors, which are usually (B) Hoistways. Busways shall not be installed in hoistways. copper or aluminum bars, rods, or tubes. (C) Hazardous Locations. Busways shall not be installed FPN: For cablebus, refer to Article 370. in any hazardous (classified) location, unless specifically approved for such use. Il. Installation FPN: See 501.10(8). 368.10 Uses Permitted. Busways shall be permitted to be (D) Wet Locations.Busways shall not be installed outdoors installed where they are located in accordance with or in wet or damp locations unless identified for such use. 368.10(A) through (C). (E) Working Platform. Lighting busway and trolley (A) Exposed. Busways shall be permitted to be located in busway shall not be installed less than 2.5 m (8 ft) above the open where visible, except as permitted in 368.10(C). the floor or working platform unless provided with a cover (B) Concealed. Busways shall be permitted to be installed identified for the purpose. behind access panels, provided the Busways are totally en- 368.17 Overcurrent Protection. Overcurrent protection closed, of nonventilati ng-type construction,and installed so shall be provided in accordance with 368.17(A) through (D). that the joints between sections and at fittings are accessible for maintenance purposes. Where installed behind access (A) Rating of Overcurrent Protection — Feeders. A panels, means of access shall be provided, and either of the busway shall be protected against overcurrent in accor- following conditions shall be met: dance with the allowable current rating of the busway. (1) The space behind the access panels shall not be used Exception No. 1: The applicable provisions of 240.4 .shall for air-handling purposes. be permitted. (2) Where the space behind the access panels is used for Exception No. 2: Where used as transformer secondary environmental air, other than ducts and plenums, there ties, the provisions of 450.6(A)(3) shall be permitted shall be no provisions for plug-in connections, and the conductors shall be insulated. (B) Reduction in Ampacity Size of Busway. Overcurrent protection shall be required where busways are reduced in (C) Through Walls and Floors. Busways shall be permit- ampacity. ted to be installed through walls or floors in accordance with (C)(I} and (C)(2). Exception: For industrial establishments only, omission of overcurrent protection shall be permitted at points where (1) Walls. Unbroken lengths of busway shall be permitted Busways are reduced in ampacity, provided that the length to be extended through dry walls. of the Busway having the smaller ampacity does not exceed 70-214 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 368—BUS WAYS 368.120 15 in (50 ft)and has an ampacit}•at least equal to one-third (16) Surface nonmetallic raceway the rating or.setting of the overcurrent device next back on the line, and provided that such busway is free from contact Where a separate equipment grounding conductor is with combustible material. used, connection of the equipment grounding conductor to the busway shall comply with 250.8 and 250.12. (C) Feeder or Branch Circuits. Where a busway is used as a feeder, devices or plug-in connections for tapping off (B) Cord and Cable Assemblies. Suitable cord and cable feeder or branch circuits from the busway shall contain the assemblies approved for extra-hard usage or hard usage and overcurrent devices required for the protection of the feeder listed bus drop cable shall be permitted as branches from or branch circuits. The plug-in device shall consist of an busways for the connection of portable equipment or the externally operable circuit breaker or an externally operable connection of stationary equipment to facilitate their inter- fusible switch. Where such devices are mounted out of change in accordance with 400.7 and 400.8 and the follow- reach and contain disconnecting means, suitable means ing conditions: such as ropes, chains, or sticks shall be provided for oper- (1) The cord or cable shall be attached to the building by ating the disconnecting means from the floor. an approved means. Exception No. 1: As permitted in 240.21. (2) The length of the cord or cable from a busway plug-in Exception No. 2: For fixed or semifis•ed luminaires, where device to a suitable tension take-up support device shall the branch-circuit overcurrent device is part of the lumi- not exceed 1.8 m (6 ft). noire cord plug on cord-connected luminaires. (3) The cord and cable shall be installed as a vertical riser Exception No. 3: Where luminaires without soaks are from the tension take-up support device to the equip- plugged direc•tlY into the busway and the overcurrent device ment served. is mounted on the kuninaire• (4) Strain relief cable grips shall be provided for the cord (D) Rating of Overcurrent Protection — Branch Cir- or cable at the busway plug-in device and equipment suits. A busway used as a branch circuit shall be protected terminations, against overcurrent in accordance with 210.20. Exception to (B)(2): In industrial establishments onht where the conditions of maintenance and supervision en- 368.30 Support. Busways shall be securely supported at sure that only qualified persons service the installation, intervals not exceeding 1.5 m (5 ft) unless otherwise de- lengths exceeding 1.8 m (6 ft) shall be permitted between signed and marked. the busway plug-in device and the tension take-up support p •su In 368.56 Branches from Busways. Branches from busways device where the cord or cable is supported at intervals not shall be permitted to be made in accordance with exceeding 2.5 m (8 ft). 368.56(A), (B), and (C). (C) Branches from "Trolley-Type Busways. Suitable cord (A) General.Branches from busways shall be permitted to and cable assemblies approved for extra-hard usage or hard use any of the following wiring methods: usage and listed bus drop cable shall be permitted as (1) Type AC armored cable branches from trolley-type busways for the connection of (2) Type MC metal-clad cable movable equipment in accordance with 400.7 and 400.8. (3) Type MI mineral-insulated, metal-sheathed cable 368.58 Dead Ends. A dead end of a busway shall be (4) Type IMC intermediate metal conduit closed. (5) Type RMC rigid metal conduit (6) Type FMC flexible metal conduit 368.60 Grounding. Busway shall be connected to an (7) Type LFMC liquidtight flexible metal conduit equipment grounding conductor(s), to an equipment bond- (8) Type PVC rigid polyvinyl chloride conduit ing jumper, or to the grounded conductor where permitted (9) Type RTRC reinforced thermosetting resin conduit or required by 250.92(B)(1) or 250.142. (10) Type LFNC liquidtight flexible nonmetallic conduit (11) Type EMT electrical metallic tubing III. Construction (12) Type ENT electrical nonmetallic tubing 368.120 Marking. Busways shall be marked with the volt- (13) Busways age and current rating for which they are designed, and (14) Strut-type channel raceway with the manufacturer's name or trademark in such a man- (15) Surface metal raceway ner as to be visible after installation. 2008 Edition NATIONAL ELECTRICAL CODE 70-215 368.214 ARTICLE 370 CABLEBUS IV. Requirements for Over 600 Volts, Nominal 368.244 Expansion Fittings. Flexible or expansion con- nections shall be provided in long, straight runs of bus to 368.214 Adjacent and Supporting Structures. Metal- allow for temperature expansion or contraction, or where enclosed busways shall be installed so that temperature rise the busway run crosses building vibration insulation joints. from induced circulating currents in any adjacent metallic parts will not be hazardous to personnel or constitute a fire 368.258 Neutral Conductor.Neutral bus, where required, bazard. shall be sized to carry all neutral load current, including harmonic currents, and shall have adequate momentary and 368.234 Barriers and Seals. short-circuit rating consistent with system requirements. (A) Vapor Seals. Busway runs that have sections located 368.260 Grounding. Metal-enclosed busway shall be both inside and outside of buildings shall have a vapor seal grounded. at the building wall to prevent interchange of air between indoor and outdoor sections. 368.320 Marking. Each busway run shall be provided Exception: Vapor seals shall Prat be required in forced- with a permanent nameplate on which the following infor- cooled bus. mation shall be provided: (1) Rated voltage. (B) Fire Barriers. Fire barriers shall be provided where (2) Rated continuous current, if bus is forced-cooled, both fire walls, floors, or ceilings are penetrated. the normal forced-cooled rating and the self-cooled FPN: See 300.21 for information concerning the spread of (not forced-cooled) rating for the same temperature rise shall be given. fire or products of combustion. (3) Rated frequency. 368.236 Drain Facilities. Drain plugs, filter drains, or (4) Rated impulse withstand voltage. similar methods shall be provided to remove condensed (5) Rated 60-Hz withstand voltage (dry). moisture from low points in busway run. (6) Rated momentary current. 368.237 Ventilated Bus Enclosures. Ventilated busway (7) Manufacturer's name or trademark. enclosures shall be installed in accordance with Article I10, FPN: See ANSI 037.23-1987 (R1991), Guide for Metal- Part III, and 490.24. Enclosed Bus and Calculating losses in Isolated-Phase Bus, for construction and testing requirements for metal- enclosed buses. 368.238 Terminations and Connections. Where bus en- closures terminate at machines cooled by flammable gas, seal-off bushings, baffles, or other means shall be provided to prevent accumulation of flammable gas in the busway enclosures. ARTICLE 370 All conductor termination and connection hardware Cablebus shall be accessible for installation, connection, and maintenance. 370.1 Scope. This article covers the use and installation 368.239 Switches. Switching devices or disconnecting requirements of cablebus and associated fittings. links provided in the busway run shall have the same mo- mentary rating as the busway. Disconnecting links shall be 370.2 Definition. plainly marked to be removable only when bus is de- Cablebus. An assembly of insulated conductors with fit- energized. Switching devices that are not load-break shall tings and conductor terminations in a completely enclosed, be interlocked to prevent operation under load, and discon- ventilated protective metal housing. Cablebus is ordinarily necting link enclosures shall be interlocked to prevent ac- assembled at the point of installation from the components cess to energized parts. furnished or specified by the manufacturer in accordance with instructions for the specific job. This assembly is de- 368.240 Wiring 600 Volts or Less, Nominal. Secondary signed to carry fault current and to withstand the magnetic control devices and wiring that are provided as part of the forces of such current. metal-enclosed bus run shall be insulated by fire-retardant barriers from all primary circuit elements with the excep- 370.3 Use. Approved cablebus shall be permitted at any tion of short lengths of wire, such as at instrument trans- voltage or current for which spaced conductors are rated former terminals. and shall be installed only for exposed work, except as 70—.216 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 372--CELLULAR CONCRETE FLOOR RACEWAYS 372.2 permitted in 370.6. Cablebus installed outdoors or in cor- fire walls, provided the section within the wall is continu- rosive, wet, or damp locations shall be identified for such ous, protected against physical damage, and unventilated. use. Cablebus shall not be installed in hoistways or hazard- ous (classified) locations unless specifically approved for {C) Through Dry Floors and Platforms. Except where such use. Cablebus shall be permitted to be used for branch firestops are required, cablebus shall be permitted to extend vertically through dry floors and platforms, provided the circuits, feeders, and services. cablebus is totally enclosed at the point where it passes Cablebus framework, where bonded, shall be permitted through the floor or platform and for a distance of 1.8 m to be used as the equipment grounding conductor for (6 ft) above the floor or platform. branch circuits and feeders. (D) Through Floors and Platforms in Wet Locations. 370.4 Conductors. Except where firestops are required, cablebus shall be per- mitted to extend vertically through floors and platforms in (A) Types of Conductors. The current-carrying conduc- wet locations where (1) there are curbs or other suitable tors in cablebus shall have an insulation rating of 75°C means to prevent waterflow through the floor or platform application.) or higher and be an approved type suitable for the opening, and (2) where the cablebus is totally enclosed at applic the point where it passes through the floor or platform and (B) Ampacity of Conductors. The ampacity of conduc- for a distance of 1.8 m (6 ft) above the floor or platform. tors in cablebus shall be in accordance with Table 310.17 370.7 Fittings. A cablebus system shall include approved and Table 310.19, or with Table 310.69 and Table 310.70 fittings for the following: for installations over 600 volts. (1) Changes in horizontal or vertical direction of the run (C) Size and Number of Conductors. The size and num- (2) Dead ends ber of conductors shall be that for which the cablebus is (3) Terminations in or on connected apparatus or equip- designed, and in no case smaller than 110 AWG. ment or the enclosures for such equipment (4) Additional physical protection where required, such as (D) Conductor Supports. The insulated conductors shall guards where subject to severe physical damage be supported on blocks or other mounting means designed for the purpose. 370.8 Conductor Terminations. Approved terminating The individual conductors in a cablebus shall be sup- means shall be used for connections to cablebus conduc- ported at intervals not greater than 900 mm (3 ft} for hori- tors, zontal runs and 450 mm (11/2 ft) for vertical runs. Vertical and horizontal spacing between supported conductors shall 370.9 Grounding, A cablebus installation shall be not be less than one conductor diameter at the points of grounded and bonded in accordance with Article 250, ex- cluding 250.86, Exception No. 2. support. 370.10 Marking. Each section of cablebus shall be 370.5 Overcurrent Protection. Cablebus shall be pro- marked with the manufacturer's name or trade designation tected against overcurrent in accordance with the allowable and the maximum diameter, number, voltage rating, and ampacity of the cablebus conductors in accordance with ampacity of the conductors to be installed. Markings shall 240.4. be located so as to be visible after installation. Exception: Overcurrenl protection shall be permitted in accordance with 240.100 and 240.101 for over 600 volts, nominal. ARTICLE 372 370.6 Support and Extension Through Walls and Cellular Concrete Floor Raceways Floors. 372.1 Scope. This article covers cellular concrete floor (A) Support. Cablebus shall be securely supported at in- raceways, the hollow spaces in floors constructed of precast servals not exceeding 3.7 m (12 ft}. cellular concrete slabs, together with suitable metal fittings Exception: Where spans longer than 3.7 m (12 f7) are re- designed to provide access to the floor cells. quired, the structure shall be specifically designed for the 372.2 Definitions. required span length. Cell. A single, enclosed tubular space in a floor made of (B) Transversely Routed. Cablebus shall be permitted to precast cellular concrete slabs, the direction of the cell be- extend transversely through partitions or walls, other than ing parallel to the direction of the floor member. 2008 Edition NATIONAL ELECTRICAL CODE 70.-.217 372.4 ARTICLE 374—CELLULAR METAL FLOOR RACEWAYS Header. Transverse metal raceways for electrical conduc- 372.11 Maximum Number of Conductors. The com- tors, providing access to predetermined cells of a precast bined cross-sectional area of all conductors or cables shall cellular concrete floor, thereby permitting the installation of not exceed 40 percent of the cross-sectional area of the cell electrical conductors from a distribution center to the floor or header. cells. 372.12 Splices and Taps. Splices and taps shall be made 372.4 Uses Not Permitted. Conductors shall not be in- only in header access units or junction boxes. stalled in precast cellular concrete floor raceways as follows: For the purposes of this section, so-called loop wiring (1) Where subject to corrosive vapor (continuous unbroken conductor connecting the individual (2) In any hazardous(classified)location,except as permit- outlets) shall not be considered to be a splice or tap. ted by other articles in this Code (3) In commercial garages, other than for supplying ceiling 372.13 Discontinued Outlets. When an outlet is aban- outlets or extensions to the area below the floor but not doned, discontinued, or removed, the sections of circuit above conductors supplying the outlet shall be removed from the raceway. No splices or reinsulated conductors, such as FPN: See 300.8 for installation of conductors with other would be the case of abandoned outlets on loop wiring, systems. shall be allowed in raceways. 3725 Header. The header shall be installed in a straight 372.17 Ampacity of Conductors. The ampacity adjust- line at right angles to the cells. The header shall be me- ment factors, provided in 310.15(B)(2), shall apply to con- chanically secured to the top of the precast cellular concrete ductors installed in cellular concrete floor raceways. floor. The end joints shall be closed by a metal closure fitting and sealed against the entrance of concrete. The header shall be electrically continuous throughout its entire length and shall be electrically bonded to the enclosure of the distribution center. ARTICLE 374 Cellular Metal Floor Raceways 372.6 Connection to Cabinets and Other Enclosures. Connections from headers to cabinets and other enclosures shall be made by means of listed metal raceways and Iisted 374.1 Scope. This article covers the use and installation fittings. requirements for cellular metal floor raceways. 372.7 Junction Boxes. Junction boxes shall be leveled to 374.2 Definitions. the floor grade and sealed against the free entrance of water or concrete. Junction boxes shall be of metal and shall be Cellular Metal Floor Raceway. The hollow spaces of cel- mechanically and electrically continuous with the header. lular metal floors, together with suitable fittings, that may be approved as enclosures for electrical conductors. 372.8 Markers. A suitable number of markers shall be Cell. A single enclosed tubular space in a cellular metal installed for the future location of cells. floor member, the axis of the cell being parallel to the axis of the metal floor member. 372.9 Inserts. Inserts shall be leveled and sealed against the entrance of concrete. Inserts shall be of metal and shall Header. A transverse raceway For electrical conductors, providing access to predetermined cells of a cellular metal be fitted with grounded-type receptacles. A grounding con- floor, thereby permitting the installation of electrical con- ductor shall connect the insert receptacles to a positive ductors from a distribution center to the cells. ground connection provided on the header. Where cutting through the cell wall for setting inserts or other purposes (such as providing access openings between header and 374.3 Uses Not Permitted. Conductors shall not be in- ceIls), chips and other dirt shall not be allowed to remain in stalled in cellular metal floor raceways as follows: the raceway, and the tool used shall be designed so as to (1) Where subject to corrosive vapor prevent the tool from entering the cell and damaging the (2) In any hazardous(classified)location,except as permit- conductors, ted by other articles in this Code (3) In commercial garages,other than for supplying ceiling 372.10 Size of Conductors. No conductor larger than 110 outlets or extensions to the area below the floor but not AWG shall be installed, except by special permission. above 70-218 NATIONAL HLECIMICAL CODE 2008 Edition ARTICLE 376—METAL WIREWAYS 376.10 FPN: See 300.8 for installation of conductors with other FPN: Liquidtight flexible metal conduit and liquidtight systems. flexible nonmetallic conduit that is suitable for installation in concrete is listed and marked for direct burial. I. Installation 374.17 Ampacity of Conductors. The ampacity adjust- 374.4 Size of Conductors. No conductor larger than 110 ment factors in 310.15(B)(2) shall apply to conductors in- AWG shall he installed, except by special permission. stalled in cellular metal floor raceways. 374.5 Maximum Number of Conductors in Raceway. II. Construction Specifications The combined cross-sectional area of all conductors or cables shall not exceed 40 percent of the interior cross- 374.100 General. Cellular metal floor raceways shall be sectional area of the cell or header. constructed so that adequate electrical and mechanical con- tinuity of the complete system will be secured. They shall 374.6 Splices and Taps. Splices and taps shall be made provide a complete enclosure for the conductors. The inte- only in header access units or junction boxes. rior surfaces shall be free from burrs and sharp edges, and For the purposes of this section, so-called loop wiring surfaces over which conductors are drawn shall be smooth. (continuous unbroken conductor connecting the individual Suitable bushings or fittings having smooth rounded edges outlets) shall not be considered to be a splice or tap. shall be provided where conductors pass. 374.7 Discontinued Outlets. When an outlet is aban- doned, discontinued, or removed, the sections of circuit conductors supplying the outlet shall be removed from the raceway. No splices or reinsulated conductors, such as ARTICLE 376 would be the case with abandoned outlets on loop wiring, Metal Wireways shall be allowed in raceways. 374.8 Markers. A suitable number of markers shall be i. General installed for locating cells in the future, 376.1 Scope. This article covers the use, installation, and 374.9 Junction Boxes. Junction boxes shall be leveled to construction specifications for metal wireways and associ- the floor grade and sealed against the free entrance of water ated fittings. or concrete. Junction boxes used with these raceways shall be of metal and shall be electrically continuous with the 376.2 Definition. raceway. Metal Wireways. Sheet metal troughs with hinged or re- 374.10 Inserts. Inserts shall be leveled to the floor grade movable covers for housing and protecting electrical wires and sealed against the entrance of concrete. Inserts shall be and cable and in which conductors are laid in place after of metal and shall be electrically continuous with the race- the wireway has been installed as a complete system. way. In cutting through the cell wall and setting inserts, chips and other dirt shall not be allowed to remain in the raceway, 11. Installation and tools shall be used that are designed to prevent the tool from entering the cell and damaging the conductors. 376.10 Uses Permitted. The use of metal wireways shall 374.11 Connection to Cabinets and Extensions from be permitted in the following: Cells. Connections between raceways and distribution cen- (l) For exposed work ters and wall outlets shall be made by means of liquidtight (2) In concealed spaces as permitted in 376.10(4) flexible metal conduit, flexible metal conduit where not (3) In hazardous (classified) locations as permitted by installed in concrete, rigid metal conduit, intermediate 501.10(B) for Class I, Division 2 locations; 502.10(8) metal conduit, electrical metallic tubing, or approved fit- for Class 11, Division 2 locations;and 504.20 for intrin- tings. Where there are provisions for the termination of an sically safe wiring. Where installed in wet locations, equipment grounding conductor, nonmetallic conduit, elec- wireways shall be listed for the purpose. trical nonmetallic tubing, or liquidtight flexible nonmetallic (4) As extensions to pass transversely through walls if the conduit shall be permitted. Where installed in concrete, liq- length passing through the wail is unbroken. Access to uidtight flexible nonmetallic conduit shall be listed and the conductors shall be maintained on both sides of the marked for direct burial. wail. 2008 Edition NATIONAL ELECTRICAL CODE 70--219 376.12 ARTICLE 376—METAL WIREWAYS 376.12 Uses Not Permitted. Metal wireways shall not be intervals.The distance between supports shall not exceed used in the following: 3 m (10 ft). (1) Where subject to severe physical damage {2) Where subject to severe corrosive environments (B) Vertical Support. Vertical runs o1' wireways shall be securely supported at intervals not exceeding 4.5 m (15 ft) and shall not have more than one joint between supports. 376.21 Size of Conductors. No conductor larger than that Adjoining wireway sections shall be securely fastened for which the wireway is designed shall be installed in any to- gether to provide a rigid joint. wireway. 376.22 Number of Conductors and Ampacity.The num- 376.56 Splices, Taps, and Power Distribution Blocks. ber of conductors and their ampacity shall comply with (A) Splices and Taps. Splices and taps shall be permitted 376.22(A) and (B). within a wireway, provided they are accessible. The con- ductors, including splices and taps, shall not fill the wire- (A) Cross-Sectional Areas of Wireway. The sum of the way to more than 75 percent of its area at that point, cross-sectional areas of all contained conductors at any cross section of a wireway shall not exceed 20 percent of (B) Power Distribution Blocks. the interior cross-sectional area of the wireway. (1) Installation. Power distribution blocks installed in (B) Adjustment Factors. The adjustment factors in metal wireways shall be listed. 310.15(B)(2)(a) shall be applied only where the number of (2) Size of Enclosure. In addition to the wiring space re- current-carrying conductors, including neutral conductors quirement in 376.56(A), the power distribution block shall classified as current-carrying under the provisions of be installed in a wireway with dimensions not smaller than 310.15(3)(4), exceeds 30. Conductors for signaling circuits specified in the installation instructions of the power distri- or controller conductors between a motor and its starter and bution block. used only for starting duty shall not be considered as current-carrying conductors. (3) Wire Bending Space. Wire bending space at the ter- minals of power distribution blocks shall comply with 376.23 Insulated Conductors. Insulated conductors in- 312.6(B). stalled in a metallic wireway shall comply with 376.23(A) (4) Live Parts. Power distribution blocks shall not have and (B). uninsulated live parts exposed within a wireway, whether (A) Deflected Insulated Conductors. Where insulated or not the wireway cover is installed. conductors are deflected within a metallic wireway, either 376.58 Dead Ends. Dead ends of metal wireways shall be at the ends or where conduits, fittings, or other raceways or closed. cables enter or leave the metallic wireway, or where the direction of the metallic wireway is deflected greater than 376.70 Extensions from Metal Wireways. Extensions 30 degrees, dimensions corresponding to one wire per ter- from wireways shall be made with cord pendants installed minal in Table 312.6(A) shall apply. in accordance with 400.10 or with any wiring method in {B} Metallic wireways Used as Pull Boxes. Where insu- Chapter 3 that includes a means for equipment grounding. Where a separate equipment grounding conductor is em- way, conductors 4 AWG or larger are pulled through awire- played, connection of the equipment grounding conductors way,the distance between raceway and cable entries enclosing in the wiring method to the wireway shall comply with the same conductor shall not be less than that required by 250.8 and 250.12. 314.28(A)(1) for straight pulls and 314.28(A)(2) for angle pulls.When transposing cable size into raceway size,the mini- mum metric designator (trade size) raceway required for the III. Construction Specifications number and size of conductors in the cable shall be used. 376.100 Construction. 376.30 Securing and Supporting. Metal wireways shall (A) Electrical and Mechanical Continuity. Wireways be supported in accordance with 376.30(A) and (B). shall be constructed and installed so that adequate electrical (A) Horizontal Support. Wireways shall be supported and mechanical continuity of the complete system is secured. where run horizontally at each end and at intervals not to (B) Substantial Construction. Wireways shall be of sub- exceed 1.5 m(5 ft)or for individual lengths longer than 1.5 m stantiai construction and shall provide a complete enclosure (5 ft) at each end or joint, unless listed for other support for the contained conductors.All surfaces,both interior and 70-220 NATIONAL ELEMRICAL CODE 2WH Edition ARTICLE 378—NONMETALLIC WIREWAYS 378.23 exterior, shall be Suitably protected fxom corrosion.Conger (4) As extensions to pass transversely through walls if the joints shall be made tight, and where the assembly is held length passing through the wall is unbroken.Access to together by rivets,bolts, or screws, such fasteners Shah be the conductors shall he maintained on both sides of the Spaced not more than 300 mm (12 in.) apart. wall. (C) Smooth Rounded Edges. Suitable bushings, shields, 378.12 Uses Not Permitted. Nonmetallic wireways shall or fittings having smooth,rounded edges shall be provided not be used in the following: where conductors pass between wireways, through parti- (1) Where subject to physical damage tions, around bends, between wireways and cabinets or (2) In any hazardous (classified)location,except as permit- junction boxes, and at ether locations where necessary to ted by other articles in this Code prevent abrasion of the insulation of the conductors. (3) Where exposed to sunlight unless listed and marked as (D) Covers. Covers shall be securely fastened to the suitable for the purpose wireway. (4) Where subject to ambient temperatures other than those for which nonmetallic wireway is listed 376.120 Marking. Metal wireways shall be so marked that (5) For conductors whose insulation temperature limita- their manufacturer's name or trademark will be visible after tions would exceed those for which the nonmetallic installation. wireway is listed 378.21 Size of Conductors. No conductor larger than that for which the nonmetallic wireway is designed shall be ARTICLE 378 installed in any nonmetallic wireway. Nonmetallic Wireways 378.22 Number of Conductors. The sum of cross- sectional areas of all contained conductors at any cross section of the nonmetallic wireway shall not exceed 20 per- I. General cent of the interior cross-sectional area of the nonmetallic 378.1 Scope. This article covers the use, installation, and wireway. Conductors for signaling circuits or controller construction specifications for nonmetallic wireways and conductors between a motor and its starter and used only associated fittings. for starting duty shall not be considered as current-carrying conductors. 378.2 Definition. The derating factors specified in 310.15(13)(2)(a) shall be applicable to the current-carrying conductors up to and Nonmetallic Wireways. Flame retardant, nonmetallic including the 20 percent fill specified above. troughs with removable covers for housing and protecting electrical wires and cables in which conductors are laid in 378.23 Insulated Conductors. Insulated conductors in- place after the wireway has been installed as a complete stalled in a nonmetallic wireway shall comply with system. 378.23(A) and (B). (A) Deflected Insulated Conductors. Where insulated 378.6 Listing Requirements. Nonmetallic wireways and conductors are deflected within a nonmetallic wireway, ei- associated fittings shall be listed. ther at the ends or where conduits, fittings, or other race- ways or cables enter or leave the nonmetallic wireway, or 11. Installation where the direction of the nonmetallic wireway is deflected greater than 30 degrees, dimensions corresponding to one 378.10 Uses Permitted. The use of nonmetallic wireways wire per terminal in Table 312.6(A) shall apply. shall be permitted in the following: (1) Only for exposed work, except as permitted in (B) Nonmetallic Wireways Used as Pull Boxes. Where 378.10(4). insulated conductors 4 AWG or larger are pulled through a wireway, the distance between raceway and cable entries (2) Where subject to corrosive environments where identi- enclosing the same conductor shall not be less than that fied for the use. required in 314.28(A)(1) for straight pulls and in (3) In wet locations where listed for the purpose. 314.28(A)(2) for angle pulls. When transposing cable size into raceway size, the minimum metric designator (trade FI'N: Extreme cold may cause nonmetallic wireways to g become brittle and therefore more susceptible to damage size) raceway required for the number and size of conduc- from physical contact. tors in the cable shall be used. 2008 Edition NATIONAL ELECTRICAL CODE 70-221 378.30 ARTICLE 382--NONMETALLIC EXTENSIONS 378.30 Securing and Supporting. Nonmetallic wireway shall be supported in accordance with 378.30(A) and (B). ARTICLE 380 (A) Horizontal Support. Nonmetallic wireways shall be Multioutlet Assembly supported where run horizontally at intervals not to exceed 900 mm (3 ft), and at each end or joint, unless listed for 380.1 Scope. This article covers the use and installation other support intervals, in no case shall the distance be- requirements for multioutlet assemblies. tween supports exceed 3 m (10 ft). (B) Vertical Support. Vertical runs of nonmetallic wire- 380.2 Use. way shall be securely supported at intervals not exceeding (A) Permitted.The use of a multioutlet assembly shall be 1.2 m (4 ft), unless listed for other support intervals, and permitted in dry locations. shall not have more than one joint between supports. Ad- joining nonmetallic wireway sections shall be securely fas- Not Permitted. A multioutlet assembly shall not be ins tened together to provide a rigid joint. installed as follows: (1) Where concealed, except that it shall be permissible to 378.44 Expansion Fittings. Expansion fittings for nonme- surround the back and sides of a metal multioutlet as- tallic wireway shall be provided to compensate for thermal sembly by the building finish or recess a nonmetallic expansion and contraction where the length change is ex- multioutlet assembly in a baseboard pected to be 6 mm (0.25 in.) or greater in a straight run. (2) Where subject to severe physical damage FPN: See Table 352.44 for expansion characteristics of (3) Where the voltage is 300 volts or more between con- PVC conduit. The expansion characteristics of PVC non- ductors unless the assembly is of metal having a thick- metallic wireway are identical. ness of not less than 1.02 mm (0.040 in.) subject to corrosive vapors sub 378.56 Splices and Taps. Splices and taps shall be permit- (5) In(4) Where e subys ted within a nonmetallic wireway, provided they are acces- sible. The conductors, including splices and taps, shall not (6) In any hazardous(classified)location, except as permit- till the nonmetallic wireway to more than 75 percent of its ted by other articles in this Code area at that point. 380.3 Metal Multioutlet Assembly Through Dry Parti- 378.58 Dead Ends. Dead ends of nonmetallic wireway tions. It shall be permissible to extend a metal multioutlet assembly through (not run within)dry partitions if arrange- ments are made for removing the cap or cover on all ex- 378.60 Grounding. Where equipment grounding is re- posed portions and no outlet is located within the partitions. quired, a separate equipment grounding conductor shall be installed in the nonmetallic wireway. A separate equipment grounding conductor shall not be required where the grounded conductor is used to-round equipment as permit- ARTICLE 3$2 ted in 250.142. Nonmetallic Extensions 378.70 Extensions from Nonmetallic Wireways. Exten- sions from nonmetallic wireway shall be made with cord 1. General pendants or any wiring method of Chapter 3. A separate equipment grounding conductor shall be installed in, or an 382.1 Scope. This article covers the use, installation, and equipment grounding connection shall be made to, any of construction specifications for nonmetallic extensions. the wiring methods used for the extension. 382.2 Definitions. IIl. Construction Specifications Concealable Nonmetallic Extension. A listed assembly of two, three, or four insulated circuit conductors within a 378.120 Marking. Nonmetallic wireways shall be marked nonmetallic jacket, an extruded thermoplastic covering, or so that the manufacturer's name or trademark and interior a sealed nonmetallic covering. The classification includes cross-sectional area in square inches shall be visible after surface extensions intended for mounting directly on the installation. Marking for limited smoke shall be permitted surface of walls or ceilings, and concealed with paint, tex- on the nonmetallic wireways that have limited smoke- tune,joint compound,plaster,wallpaper,tile,wall paneling, producing characteristics. or other similar materials. 70-222 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 382—NONMETALLIC EXTENSIONS 382.42 Nonmetallic Extension. An assembly of two insulated ing outlet,but not on the floor or within 50 mm(2 in.)from conductors within a nonmetallic jacket or an extruded then- the floor. moplastie covering. The classification includes surface ex- tensions intended for mounting directly on the surface of (B) Concealable Nonmetallic Extensions. Where identi- walls or ceilings. fied for the use, nonmetallic extensions may be concealed with paint, texture, concealing compound, plaster, wallpa- 382.6 Listing Requirements.Concealable nonmetallic ex- per, tile, wall paneling, or other similar materials and in- tensions and associated fittings and devices shall be listed. stalled per 382.15(A). The starting/source tap device for the extension shall con- tain and provide the following protection for all load-side 382.26 Bends. extensions and devices. (1) Supplementary overcurrent protection (A) Nonmetallic Extensions. A bend that reduces the nor- mal spacing between the conductors shall be covered with a (2) Level of protection equivalent to a Class A GFCI cap to protect the assembly from physical damage. (3) Level of protection equivalent to a portable GFC1 (4) Line and load-side miSwire protection (B) Concealable Nonmetallic Extensions. Concealable extensions shall be permitted to be folded back over them- (5) Provide protection from the effects of are faults selves and flattened as required for installation. II. installation 382.30 Securing and Supporting. 382.10 Uses Permitted. Nonmetallic extensions shall be (A) ,Nonmetallic Extensions. Nonmetallic surface exten- permitted only in accordance with 382.10(A), (B), and (C). sions shall be secured in place by approved means at inter- (A) From an Existing Outlet.The extension shall be from vals not exceeding 200 mm (8 in.), with an allowance for an existing outlet on a 15- or 20-ampere branch circuit. 300 mm (12 in.) to the first fastening where the connection Where a concealable nonmetallic extension originates from to the supplying outlet is by means of an attachment plug. a non—grounding-type receptacle,the installation shall comply There shall be at least one fastening between each two with 250.130(C),406.3(D)(3)(b), or 406.3(D)(3)(c). adjacent outlets supplied. An extension shall be attached to only woodwork or plaster finish and shall not be in contact (B) Exposed and in a Dry Location. The extension shall with any metal work or other conductive material other be run exposed, or concealed as permitted in 382.15,and in than with metal plates on receptacles. a dry location. (C) Residential or Offices. For nonmetallic surface exten- (B) Concealable Nonmetallic Extension$. All surface- mounted concealable nonmetallic extension components shall sions mounted directly on the surface of walls or ceilings, be firmly anchored to the wall or ceiling using an adhesive or the building shall be occupied for residential or office pur- mechanical anchoring system identified for this use. poses and shall not exceed three floors abovegrade. Where identified for the use, concealable nonmetallic extensions 382,40 Boxes and Fittings. Each run shall terminate in a shall be permitted more than three floors abovegrade. fitting, connector, or box that covers the end of the assem- FPN No. 1: See 310.10 for temperature limitation of bly, All fittings, connectors, and devices shall be of a type conductors. identified for the use. FPN No. 2: See 362.10 for definition of First Floor. 382.42 Devices. 382.12 Uses Not Permitted. Nonmetallic extensions shall not be used as follows: (A) Receptacles. All receptacles,receptacle housings, and (1) In unfinished basements, attics, or roof spaces self-contained devices used with concealable nonmetallic (2) Where the voltage between conductors exceeds 150 extensions shall be identified for this use. volts for nonmetallic surface extensions and 300 volts (B) Receptacles and Housings. Receptacle housings and for aerial cable self-contained devices designed either for surface or for (3) Where subject to corrosive vapors recessed mounting shall be permitted for use with conceal- (4) Where run through a floor or partition, or outside the able nomnetal'lic extensions. Receptacle housings and self- room in which it originates contained devices shall incorporate means for facilitating entry and termination of concealable nonmetallic ex- ten- sions Exposed. and for electrically connecting the housing or device, (A) Nonmetallic Extensions. One or more extensions Receptacle and self-contained devices shall compIy with shall be permitted to be run in any direction from an exist- 406.3.Power and communications outlets installed together 2008 Edition NATIONAL ELECTRICAL CODE 70-223 382.56 ARTICLE 384—STRUT-TYPE CHANNEL RACEWAY in common housing shall be permitted in accordance with 382.120 Marking. 800.133(A)(1)(e), Exception No. 2. (A) Cable. Concealable nonmetallic extensions shall be 382.56 Splices and Taps. Extensions shall consist of a clearly and durably marked on both sides at intervals of not continuous unbroken length of the assembly, without more than 610 mm (24 in.) with the information required splices, and without exposed conductors between fittings, by 310.11(A) and with the following additional informa- connectors, or devices. Taps shall be permitted where ap- non: proved fittings completely covering the tap connections are (1) Material of Conductors used. Aerial cable and its tap connectors shall be provided (2) Maximum temperature rating with an approved means for polarization. Receptacle-type (3) Ampacity tap connectors shall be of the locking type. (B) Conductor Identification. Conductors shall be clearly III. Construction Specifications (Concealable and durably identified on both sides throughout their length Nonmetallic Extensions only) as specified in 382.104. 382.100 Construction. Concealable nonmetallic exten- sions Shall be a multilayer flat conductor design consisting of a center ungrounded conductor enclosed by a sectioned ARTICLE 384 grounded conductor, and an overall sectioned grounding conductor. Strut-Type Channel Raceway 382.104 Flat Conductors. Concealable nonmetallic exten- 1. General sions shall be constructed, using flat copper conductors equivalent to 14 AWG or 12 AWG conductor sizes, and 384.1 Scope. This article covers the use, installation, and constructed per 382.104(A), (B), and (C). construction specifications of strut-type channel raceway. (A) Ungrounded Conductor (Center Layer). The un- 384.2 Definition. grounded conductor shall consist of one or more un- grounded flat conductor(s)enclosed per 382.104(B) and(C) Strut-Type Channel Raceway. A metallic raceway that is and identified in accordance with 310.12(C). intended to be mounted to the surface of or suspended from a structure, with associated accessories for the installation (B) Grounded Conductor(Inner Sectioned Layers).The of electrical conductors and cables. grounded conductor shall consist of two sectioned inner flat conductors that enclose the center ungrounded conduc- 384.6 Listing Requirements. Strut-type channel race- tor(s). The sectioned grounded conductor shall be enclosed ways, closure strips, and accessories shall be listed and by the sectioned grounding conductor and identified in ac- identified for such use. cordance with 200.6. (C) Grounding Conductor (Outer Sectioned Layers). 1I. Installation The grounding conductor shall consist of two overall sec- tioned conductors that enclose the grounded conductor and 384.10 Uses Permitted. The use of strut-type channel ungrounded conductor(s) and shall comply with raceways shall be permitted in the following: 250.4(A)(5).The grounding conductor layers shall be iden- (1) Where exposed. tified by any one of the following methods: (2) In dry locations. (1) As permitted in 250.119 (3) In locations subject to corrosive vapors where pro- (2) A clear covering tected by finishes judged suitable for the condition. (3) One or more continuous green stripes or hash marks (4) Where the voltage is 600 volts or less. (4) The term"Equipment Ground"printed at regular inter- (5) As power poles. vals throughout the cable (6) In Class 1, Division 2 hazardous (classified) locations as permitted in 501.10(B)(3). 382.112 Insulation. The ungrounded and grounded flat (7) As extensions of unbroken lengths through walls, par- conductor layers shall be individually insulated and comply titions, and floors where closure strips are removable with 310.10.The grounding conductor shall be covered or from either side and the portion within the wall, parti- insulated. tion, or floor remains covered. 70-224 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 384-STRUT-TYPE CHANNEL RACEWAY 384.100 (8) Ferrous channel raceways and fittings protected from Table 384.22 Channel Size and Inside Cross-Sectional Area corrosion solely by enamel shall be permitted only indoors. Area 40% Area' 25% Area Size 384.12 Uses Not Permitted. Strut-type channel raceways Channel in? mm' in.' mm' in.Z mm, shall not be used as follows: V,/a x "/16 0.887 572 0.355 229 0.222 143 (1) Where concealed. 15/8 x 1 1.151 743 0.460 297 0.288 186 (2) Ferrous channel raceways and fittings protected from V/a x 13/8 1.677 1076 0.671 433 0.419 270 corrosion solely by enamel shall not be permitted I-%x 15/8 2.028 1308 0.811 523 0.507 327 where subject to severe corrosive influences. 1518 x 27/16 3.169 2045 1.267 817 0.792 511 15/a x 3114 4.308 2780 1.723 1112 1.077 695 384.21 Size of Conductors. No conductor larger than that 1'/ x 314 0.849 548 0.340 219 0.212 137 for which the raceway is listed shall be installed in strut- 1'/2 x 1'h 1.828 1179 0.731 472 0.457 295 type channel raceways. 1'/2 x 17/8 2.301 1485 0.920 594 0.575 371 1'/2 x 3 3.854 2487 1.542 995 0.964 622 384.22 Number of Conductors. The number of conduc- tors permitted in strut-type channel raceways shall not ex- -Raceways with external joiners shall use a 40 percent wire fill cal- culation to determine the number of conductors permitted. teed the percentage fill using Table 384.22 and applicable "Raceways with internal joiners shall use a 25 percent wire fill cal- crass-sectional area of specific types and sizes of wire culation to determine the number of conductors permitted, given in the tables in Chapter 9. The derating factors of 310.15(B)(2)(a) shall not apply to conductors installed in strut-type channel raceways 384.56 Splices and Taps. Splices and taps shall be permit- where all of the following conditions are met: ted in raceways that are accessible after installation by hav- (1) The cross-sectional area of the raceway exceeds ing a removable cover. The conductors, including splices 2500 MM2 (4 in.2). and taps, shall not fill the raceway to more than 75 percent (2) The current-carrying conductors do not exceed 30 in of its area at that point. All splices and taps shall be made number, by approved methods. (3) The sum of the cross-sectional areas of all contained 384,60 Grounding. Strut-type channel raceway enclosures conductors does not exceed 20 percent of the interior providing a transition to or from other wiring methods shall cross-sectional area of the strut-type channel raceways, have a means for connecting an equipment grounding con- calculated in accordance with the following formula for ductor. Strut-type channel raceways shall be permitted as wire fill: an equipment grounding conductor in accordance with ra 250.118(13). Where a snap-fit metal cover for strut-type channel raceways is used to achieve electrical continuity in Wa accordance with the listing, this cover shall not be permit- where: ted as the means for providing electrical continuity for a n = number of wires receptacle mounted in the cover. ca = channel area in square inches wa = wire area III. Construction Specifications 384.30 Securing and Supporting. 384.100 Construction. Strut-type channel raceways and their accessories shall be of a construction that distin- (A) Surface Mount. A surface mount strut-type channel guishes them from other raceways. Raceways and their el- raceway shall be secured to the mounting surface with re- bows, couplings, and other fittings shall be designed such tention straps external to the channel at intervals not ex- that the sections can be electrically and mechanically coupled ceeding 3 m (10 ft) and within 900 mm(3 ft) of each outlet together and installed without subjecting the wires to abrasion. box, cabinet,junction box, or other channel raceway termi- They shall comply with 384.100(A), (B), and (C). nation. (A) Material. Raceways and accessories shall be formed (B) Suspension Mount. Strut-type channel raceways shall of steel, stainless steel, or aluminum. be permitted to be suspension mounted in air with approved appropriate methods designed for the purpose at intervals (B) Corrosion Protection. Steel raceways and accessories not to exceed 3 m (10 ft) and within 900 mm (3 ft) of shall be protected against corrosion by galvanizing or by an channel raceway terminations and ends. organic coating. 2008 Edition NATIONAL ELECTRICAL CODE 70-225 384.120 ARTICLE 386—SURFACE METAL RACEWAYS FPN: Enamel and PVC coatings are examples of organic (5) Where concealed, except as permitted in 386.10 coatings that provide corrosion protection. (C) Cover. Covers of strut-type channel raceways shall be 386.21 Size of Conductors. No conductor larger than that either metallic or nonmetallic. for which the raceway is designed shall be installed in surface metal raceway. 384.120 Marking. Each length of strut-type channel race- ways shall be clearly and durably identified as required in 386.22 Number of Conductors or Cables.The number of the first sentence of 110.21. conductors or cables installed in surface metal raceway shall not be greater than the number for which the raceway is designed. Cables shall be permitted to be installed where such use is not prohibited by the respective cable articles. ARTICLE 386 The derating factors of 310.15(B)(2)(a) shall not apply to conductors installed in surface metal raceways where all Surface Metal Raceways of the following conditions are met: (1) The cross-sectional area of the raceway exceeds 1. General 2500 mm` (4 in.`). 386.1 Scope. This article covers the use, installation, and (2) The current-carry ing conductors do not exceed 30 in construction specifications for surface metal raceways and number. associated fittings. (3) The sum of the cross-sectional areas of all contained conductors does not exceed 20 percent of the interior 386.2 Definition. cross-sectional area of the surface metal raceway. Surface Metal Raceway. A metallic raceway that is in- 386.30 Securing and Supporting.Surface metal raceways tended to be mounted to the surface of a structure, with shall be supported at intervals in accordance with the associated couplings, connectors,boxes, and fittings for the manufacturer's installation instructions. installation of electrical conductors. 386.6 Listing Requirements. Surface metal raceway and 386.56 Splices and Taps. Splices and taps shall be permit- associated fittings shall be listed. ted in surface metal raceways having a removable cover that is accessible after installation. The conductors, includ- ing splices and taps, shall not fill the raceway to more than II. Installation 75 percent of its area at that point. Splices and taps in 386.10 Uses Permitted. The use of surface metal race- surface metal raceways without removable covers shall be ways shall be permitted in the following: made only in boxes. All splices and taps shall be made by (I) In dry locations. approved methods. Taps of Type FC cable installed in surface metal race- (2) In Class I, Division 2 hazardous (classified) locations way shat] he made in accordance with 322.56(B). as permitted in 501.10(B)(3). (3) Under raised floors, as permitted in 645.5(D)(2). 386.60 Grounding.Surface metal raceway enclosures pro- (4) Extension through walls and floors.Surface metal race- viding a transition from other wiring methods shall have a way shall be permitted to pass transversely through dry means for connecting an equipment grounding conductor. walls, dry partitions, and dry floors if the length passing through is unbroken. Access to the conductors shall be 386.70 Combination Raceways. When combination sur- maintained on both sides of the wall, partition, or floor. face metallic raceways are used for both signaling and for lighting and power circuits, the different systems shall be 386.12 Uses Not Permitted. Surface metal raceways shall run in separate compartments identified by stamping, im- not be used in the following: printing, or color coding of the interior finish. (1) Where subject to severe physical damage, unless oth- erwise approved (2) Where the voltage is 300 volts or more between con- ductors, unless the metal has a thickness of not less 386.100 Construction. Surface metal raceways shall be of than 1.02 mm (0.040 in.) nominal such construction as will distinguish them from other race- (3) Where subject to corrosive vapors ways. Surface metal raceways and their elbows, couplings, (4) In hoistways and similar fittings shall be designed so that the sections 70-226 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 388—SURFACE NONMETALLIC RACEWAYS 388.120 can be electrically and mechanically coupled together and 388.21 Size of Conductors. No conductor larger than that installed without subjecting the wires to abrasion, for which the raceway is designed shall be installed in Where covers and accessories of nonmetallic materials surface nonmetallic raceway. are used on surface metal raceways, they shall be identified for such use. 388.22 Number of Conductors or Cables.The number of conductors or cables installed in surface nonmetallic race- way shall not be greater than the number for which the raceway is designed. Cables shall be permitted to be in- ARTICLE 388 stalled where such use is not prohibited by the respective Surface Nonmetallic Raceways cable articles. 388.30 Securing and Supporting. Surface nonmetallic I. General raceways Shall be supported at intervals in accordance with 388.1 Scope. This article covers the use, installation, and the manufacturer's installation instructions. construction specifications for surface nonmetallic race- ways and associated fittings. 388.56 Splices and Taps. Splices and taps shall be permit- ted in surface nonmetallic raceways having a cover capable 388.2 Definition. of being opened in place that is accessible after installation. Surface Nonmetallic Raceway. A nonmetallic raceway The conductors, including splices and taps, shall not fill the that is intended to be mounted to the surface of a structure, raceway to more than 75 percent of its area at that point. with associated couplings, connectors, boxes, and fittings Splices and taps in surface nonmetallic raceways without for the installation of electrical conductors. covers capable of being opened in place shall be made only in boxes. All splices and taps shall be made by approved 388.6 Listing Requirements. Surface nonmetallic race- methods. way and associated fittings shall be listed. 388.60 Grounding. Where equipment grounding is re- Il. Installation quired, a separate equipment grounding conductor shall be 388.10 Uses Permitted. Surface nonmetallic raceways installed in the raceway. shall be permitted as follows: 388.70 Combination Raceways. When combination sur- (1) The use of surface nonmetallic raceways shall be per- face nonmetallic raceways are used both for signaling and mitted in dry locations. for lighting and power circuits, the different systems shall (2) Extension through walls and floors shall be permitted. be run in separate compartments identified by stamping, Surface nonmetallic raceway shall be permitted to pass imprinting, or color coding of the interior finish. transversely through dry walls, dry partitions, and dry floors if the length passing through is unbroken.Access to the conductors shall be maintained on both sides of III. Construction Specifications the wall, partition, or floor. 388.100 Construction.Surface nonmetallic raceways shall 388.12 Uses Not Permitted. Surface nonmetallic race- be of such construction as will distinguish them from other ways shall not be used in the following: raceways. Surface nonmetallic raceways and their elbows, (1) Where concealed, except as permitted in 388.10(2) couplings, and similar fittings shall be designed so that the (2) Where subject to severe physical damage sections can be mechanically coupled together and installed without subjecting the wires to abrasion. (3) Where the voltage is 300 volts or more between con- Surface nonmetallic raceways and fittings are made of ductors, unless listed for higher voltage suitable nonmetallic material that is resistant to moisture (4) In hoistways and chemical atmospheres. It shall also be flame retardant, (5) In any hazardous(classified)location,except as permit- resistant to impact and crushing,resistant to distortion from ted by other articles in this Cade heat under conditions likely to be encountered in service, (6) Where subject to ambient temperatures exceeding those and resistant to low-temperature effects. for which the nonmetallic raceway is listed (7) For conductors whose insulation temperature limita- 388.120 Marking.Surface nonmetallic raceways that have tions would exceed those for which the nonmetallic limited smoke-producing characteristics shall be permitted raceway is listed to be so identified. 2009 Edition NATIONAL ELECTRICAL CODE 70-227 390.1 ARTICLE 390—UNDERFLOOR RACEWAYS with substantial linoleum that is not less than 1.6 mm(1/f.in.) ARTICLE 390 thick or with equivalent floor covering. Where more than one Underfloor Raceways and not more than three single raceways are each installed flush with the concrete, they shall be contiguous with each other and joined to form a rigid assembly. 390.1 Scope. This article covers the use and installation requirements for underfloor raceways. 390.4 Size of Conductors. No conductor larger than that for which the raceway is designed shall be installed in 390.2 Use. underfloor raceways. (A) Permitted. The installation of underfloor raceways 390.5 Maximum Number of Conductors in Raceway. shall be permitted beneath the surface of concrete or other The combined cross-sectional area of all conductors or flooring material or in office occupancies where laid flush cables shall not exceed 40 percent of the interior cross- with the concrete floor and covered with linoleum or sectional area of the raceway. equivalent floor covering. (B) Not Permitted. Underfloor raceways shall not be in- 390.6 Splices and Taps. Splices and taps shall be made stalled (1) where subject to corrosive vapors or (2) in any only in junction boxes. hazardous (classified) locations, except as permitted by For the purposes of this section, so-called loop wiring 504.20 and in Class 1, Division 2 locations as permitted in (continuous, unbroken conductor connecting the individual 501.10(13)(3). Unless made of a material judged suitable for outlets) shall not be considered to be a splice or tap. the condition or unless corrosion protection approved for Exception: Splices and taps shall be permitted in trench- the condition is provided, ferrous or nonferrous metal un- type flush raceway having a removable cover that is acces- derfloor raceways,junction boxes, and fittings shall not be sible after installation. The conductors, including splices installed in concrete or in areas subject to severe corrosive and taps, shall not fill more than 75 percent of the raceway influences. area at that point. 390.3 Covering. Raceway coverings shall comply with 390.7 Discontinued Outlets. When an outlet is aban- 390.3(A) through (D). doned, discontinued, or removed, the sections of circuit conductors supplying the outlet shall be removed from the (A) Raceways Not over 100 mm (4 in.}Wide. Half-round raceway. No splices or reinsulated conductors, such as and flat-top raceways not over 100 mm (4 in.) in width would be the case with abandoned outlets on loop wiring, shall have not less than 20 mm (-1/a in.)of concrete or wood shall be allowed in raceways. above the raceway. Exception: As permitted in 390.3(C) and (D)for fiat-top 390.8 Laid in Straight Lines. Underfloor raceways shall raceways be laid so that a straight line from the center of one junction box to the center of the next junction box coincides with (B) Raceways over 100 mm (4 in.) Wide But Not over the centerline of the raceway system. Raceways shall be 200 mm (8 in.) Wide. Flat-top raceways over 100 mm firmly held in place to prevent disturbing this alignment (4 in.)but not over 200 mm(8 in.) wide with a minimum of during construction. 25 mm (1 in.) spacing between raceways shall be covered with concrete to a depth of not less than 25 min (1 in.). 390.9 Markers at Ends. A suitable marker shall be in- Raceways spaced less than 25 mm (1 in.) apart shall be stalled at or near each end of each straight run of raceways covered with concrete to a depth of 38 mm (11h in.). to locate the last insert. (C) Trench-Type Raceways Flush with Concrete. 390.10 Dead Ends. Dead ends of raceways shall be Trench-type flush raceways with removable covers shall be closed. permitted to be laid flush with the floor surface. Such ap- proved raceways shall be designed so that the cover plates 390.13 Junction Boxes.Junction boxes shall be leveled to provide adequate mechanical protection and rigidity the floor grade and sealed to prevent the free entrance of equivalent to junction box covers. water or concrete.Junction boxes used with metal raceways shall be metal and shall be electrically continuous with the (D) Other Raceways Flush with Concrete. In office oc- raceways. cupancies, approved metal flat-top raceways, if not over 100 mm (4 in.) in width, shall be permitted to be laid flush 390.14 inserts. Inserts shall be leveled and sealed to with the concrete floor surface, provided they are covered prevent the entrance of concrete. Inserts used with metal 70--228 NATIONAL ELECTRICAL CODE 21X)8 Edition ARTICLE 392—CABLE TRAYS 392,3 raceways shall be metal and shall be electrically continuous Table 392.3(A) Wiring Methods with the raceway.Inserts set in or on fiber raceways before the floor is laid shall be mechanically secured to the raceway. Wiring Method Article Inserts set in fiber raceways after the floor is laid shall be screwed into the raceway. When cutting through the raceway Armored cable 320 wall and setting nserts, chips and other dirt shall not be al- CATV cables 820 g P CATV raceways $20 lowed to remain in the raceway, and tools shall be used that Class 2 and Class 3 cables 725 are designed so as to prevent the tool from entering the race- Communications cables 800 way and damaging conductors that may be in place. Communications raceways 800 Electrical metallic tubing 358 390.15 Connections to Cabinets and Wall Outlets. Con- Electrical nonmetallic tubing 362 Fire alarm cables 760 nections from underfloor raceways to distribution centers Flexible metal conduit 348 and wall outlets shall be made by approved fittings or by Flexible metallic tubing 360 any of the wiring methods in Chapter 3, where installed in Instrumentation tray cable 727 accordance with the provisions of the respective articles. Intermediate metal conduit 342 Liquidtight flexible metal conduit 350 390.17 Ampaeity of Conductors. The ampacity adjust- Liquidtight flexible nonmetallic conduit 356 Metal-clad cable 330 meat factors, in 310.15(B)(2), shall apply to conductors Mineral-insulated, metal-sheathed cable 332 installed in underfloor raceways. Multiconductor service-entrance cable 338 Multiconductor underground feeder and 340 branch-circuit cable Network-powered broadband communications 830 cables ARTICLE 392 Nonmetallic-sheathed cable 334 Non-power limited fire alarm cable 760 Cable Trays Optical fiber cables 770 Optical fiber raceways 770 Other factory-assembled, multiconductor 392.1 Scope. This article covers cable tray systems, in- control, signal, or power cables that are cludin ladder, ventilated trough, ventilated channel, solid specifically approved for installation in cable g g trays bottom, and other similar structures. Polyvinyl chloride PVC conduit 352 Power and control tray cable 336 FPN: For further information on cable trays, see Power-limited fire alarm Cable 760 ANSIINEMA--VE 1-1998, Metal Cable Tray Systems; Power-limited tray cable 725 NEMA--VE 2-1996, Metal Cable Tray Installation Guide- Rigid metal conduit 344 lines; and NEMA-FG-1998, Nonmetallic Cable Tray Rigid nonmetallic conduit 352 Systems. RTRC 355 Signaling raceway 725 392.2 Definition. Cable Tray System. A unit or assembly of units or sections (B) In Industrial Establishments. The wiring methods in and associated fittings forming a structural system used to Table 392.3(A) shall be permitted to be used in any indus- securely fasten or support cables and raceways. trial establishment under the conditions described in their respective articles. In industrial establishments only, where 392.3 Uses Permitted. Cable tray shall be permitted to be conditions of maintenance and supervision ensure that only used as a support system for service conductors, feeders, qualified persons service the installed cable tray system, branch circuits, communications circuits, control circuits, any of the cables in 392.3(B)(1)and (13)(2)shall be permit- and signaling circuits. Cable tray installations shall not be ted to be installed in ladder, ventilated trough,solid bottom, limited to industrial establishments. Where exposed to di- or ventilated channel cable trays. rect rays of the sun, insulated conductors and jacketed cables shall be identified as being sunlight resistant. Cable (1) Single Conductors. Single-conductor cables shall be trays and their associated fittings shall be identified for the permitted to be installed in accordance with (13)(1)(a) intended use, through (13)(1)(c). (A) Wiring Methods. The wiring methods in Table (a) Single-conductor cable shall be 110 AWG or larger 392.3(A) shall be permitted to be installed in cable tray and shall be of a type listed and marked on the surface for systems under the conditions described in their respective use in cable trays. Where 1/0 AWG through 410 AWG articles and sections. single-conductor cables are installed in ladder cable tray, 2008 Edition NATIONAL ELECTRICAL CODE 70-229 392.4 ARTICLE 392—CABLE TRAYS the maximum allowable rung spacing for the ladder cable 392.6 Installation. tray shall be 225 mm {4 in.}. (b) Welding cables shall comply with the provisions of (A) Complete System. Cabe trays shall be installed as a Article 630, Part IV, complete system. Field bends or modifications shall be so (c) Single conductors used as equipment grounding made that the electrical continuity of the cable tray system conductors shall be insulated, covered, or bare, and they and support for the cables is maintained.Cable tray systems shall be 4 AWG or larger. shall be permitted to have mechanically discontinuous seg- ments between cable tray runs or between cable tray runs (2) Medium Voltage. Single- and multiconductor medium and equipment.The system shall provide for the support of voltage cables shall be Type MV cable. Single conductors the cables in accordance with their corresponding articles. shall be installed in accordance with 392.3(6)(1). Where cable trays support individual conductors and where the conductors pass from one cable tray to another, (C) Equipment Grounding Conductors. Metallic cable or from a cable tray to raceway(s) or from a cable tray to trays shall be permitted to be used as equipment grounding equipment where the conductors are terminated, the dis- conductors where continuous maintenance and supervision en- tance between cable trays or between the cable tray and the sure that qualified persons service the installed cable tray sys- raceway(s) or the equipment shall not exceed 1.8 m (6 ft). tem and the cable tray complies with provisions of 392.7. The conductors shall be secured to the cable tray(s) at the transition, and they shall be protected, by guarding or by (D) Hazardous (Classified) Locations. Cable trays in haz- location, from physical damage. ardous (classified) locations shall contain only the cable types A bonding jumper sized in accordance with 250.102 permitted in 501.10, 502.10, 503.10, 504.20, and 505.15. shall connect the two sections of cable tray, or the cable (E) Nonmetallic Cable Tray. In addition to the uses per- tray and the raceway or equipment. Bonding shall be in accordance with 250.96. mitted elsewhere in 392.3, nonmetallic cable tray shall be permitted in corrosive areas and in areas requiring voltage (B) Completed Before Installation. Each run of cable isolation. tray shall be completed before the installation of cables. 392.4 Uses Not Permitted.Cable tray systems shall not be (C) Supports. Supports shall be provided to prevent stress used in hoistways or where subject to severe physical dam- on cables where they enter raceways or other enclosures age.Cable tray systems shall not be used in ducts,plenums, from cable tray systems. and other air-handling spaces, except as permitted in Cable trays shall be supported at intervals in accordance 300.22, to support wiring methods recognized for use in with the installation instructions. such spaces. (D) Covers. In portions of runs where additional protec- tion is required,covers or enclosures providing the required 392.5 Construction Specifications. protection shall be of a material that is compatible with the (A) Strength and Rigidity. Cable trays shall have suitable cable tray, strength and rigidity to provide adequate support for all (E) Multieonductor Cables Rated 600 Volts or Less. contained wiring. Multiconductor cables rated 600 volts or less shall be per- (B) Smooth Edges.Cable trays shall not have sharp edges, mitted to be installed in the same cable tray. burrs, or projections that could damage the insulation or (F) Cables Rated over 600 Volts. Cables rated over 600 jackets of the wiring. volts and those rated 600 volts or less installed in the same (C) Corrosion Protection. Cable tray systems shall be cable tray shall comply with either of the following: corrosion resistant. If made of ferrous material, the system (1) The cables rated over 600 volts are Type MC. shall be protected from corrosion as required by 300.6. (2) The cables rated over 600 volts are separated from the cables rated 600 volts or Iess by a solid fixed barrier of (D) Side Rails. Cable trays shall have side rails or equiva- a material compatible with the cable tray. lent structural members. (G) Through Partitions and Walls. Cable trays shall be (E) Fittings.Cable trays shall include fittings or other suit- permitted to extend transversely through partitions and able means for changes in direction and elevation of runs. walls or vertically through platforms and floors in wet or dry locations where the installations, complete with in- (F) Nonmetallic Cable Tray. Nonmetallic cable trays stalled cables, are made in accordance with the require- shall be made of flame-retardant material. ments of 300.2t. 70-230 NATIONAL ELECTRICAL CO DL 2009 Edition ARTICLE 392 CABLE TRAYS 392.8 (H) Exposed and Accessible.Cable trays shall be exposed Table 392.7(B) Metal Area Requirements for Cable Trays and accessible except as permitted by 392.6(G). Used as Equipment Grounding Conductor (I) Adequate Access. Sufficient space shall be provided Maximum Fuse and maintained about cable trays to permit adequate access Ampere Rating, Minimum Cross-Sectional for installing and maintaining the cables. Circuit Breaker Area of Metal' Ampere Trip Setting, (,T) Raceways, Cables, Boxes, and Conduit Bodies Sup- or Circuit Breaker ported from Cable Tray Systems. In industrial facilities Protective Relay Ampere Trip Setting Aluminum where conditions of maintenance and supervision ensure for Ground-Fault Steel Cable Trays Cable Trays that only qualified persons service the installation and Protection of Any where the cable tray systems are designed and installed to Cable Circuit in the support the load,such systems shall be permitted to support Cable Tray System mm.2 in.2 mm in.2 raceways and cables,and boxes and conduit bodies covered 60 129 0.20 129 0.20 in 314.1.For raceways terminating at the tray,a listed cable 100 258 0.40 129 0.20 tray clamp or adapter shall be used to securely fasten the 200 451.5 0.70 129 0.20 raceway to the cable tray system.Additional supporting and 400 645 1.00 258 0.40 securing of the raceway shall be in accordance with the 600 967.5 1.501, 258 0.40 requirements of the appropriate raceway article. 1000 _ _ 387 0.60 1200 645 1.00 For raceways or cables running parallel to and attached 1600 — -- 967.5 1.50 to the bottom or side of a cable tray system, fastening and 2000 — — 1290 2.001, supporting shall be in accordance with the requirements of 'Total cross-sectional area of both side rails for ladder or trough cable the appropriate raceway or cable article. trays; or the minimum cross-sectional area of metal in channel cable For boxes and conduit bodies attached to the bottom or trays or cable trays of one-piece construction. side of a cable tray system, fastening and supporting shall 1,Steel cable trays shall not be used as equipment grounding conduc- be in accordance with the requirements of 314.23. tors for circuits with ground-fault protection above 600 amperes.Alu- minum cable trays shall not be used as equipment grounding conduc- 392.7 Grounding. tors for circuits with ground-fault protection above 2000 amperes. (A) Metallic Cable Trays. Metallic cable trays that sup- cable tray, provided they are accessible. Splices sball be port electrical conductors shall be grounded as required for permitted to project above the side rails where not subject conductor enclosures in accordance with 250.96 and Part to physical damage. IV of Article 250. (B) Fastened Securely. In other than horizontal runs, the (B) Steel or Aluminum Cable Tray Systems. Steel or cables shall be fastened securely to transverse members of aluminum cable tray systems shall be permitted to be used the cable trays. as equipment grounding conductors, provided all the fol- lowing requirements are met: (C) Bushed Conduit and Tubing. A box shall not be re- quired where cables or conductors are installed in bushed (1) The cable tray sections and fittings are identified as an conduit and tubing used for support or for protection equipment grounding conductor. against physical damage. (2) The minimum cross-sectional area of cable trays con- form to the requirements in Table 392.7(B). (D) Connected in Parallel.Where single conductor cables (3) All cable tray sections and fittings are legibly and du- comprising each phase, neutral, or grounded conductor of n rably marked to show the cross-sectional area of metal alternating-current circuit are connected in parallel as permit- in channel cable trays, or cable trays of one-piece con- ted in 310.4, the conductors shall be installed in groups con- struction, and the total cross-sectional area of both side sisting of not more than one conductor per phase, neutral, or rails for ladder or trough cable trays. grounded conductor to prevent current imbalance in the paral- (4) Cable tray sections, fittings, and connected raceways leled conductors due to inductive reactance. are bonded in accordance with 250.96, using bolted Single conductors shall be securely bound in circuit mechanical connectors or bonding jumpers sized and groups to prevent excessive movement due to fault-current installed in accordance with 250.102. magnetic forces unless single conductors are cabled to- gether, such as triplexed assemblies. 392.5 Cable Installation. (E) Single Conductors.Where any of the single conductors (A) Cable Splices. Cable splices made and insulated by installed in ladder or ventilated trough cable trays are 110 approved methods shall be permitted to be located within a through 410 AWG,all single conductors shall be installed in a 2008 Edition NATIONAL ELECTRICAL CODE 70-231 392.9 ARTICLE 392-CABLE'TRAYS single layer. Conductors that are bound together to comprise sum of the cross-sectional areas of all cables smaller each circuit group shall be permitted to be installed in other than 4/0 AWG shall not exceed the maximum allow- than a single layer. able fill area resulting from the calculation in Column 2 of Table 392.9 for the appropriate cable tray width.The 392.9 Number of Multiconductor Cables, Rated 2000 410 AWG and Iarger cables shall be installed in a single Volts or Less, in Cable Trays. The number of multicon- layer, and no other cables shall be placed on them. ductor cables, rated 2000 volts or less, permitted in a single cable tray shall not exceed the requirements of this section. (B) Multiconductor Control and/or Signal Cables Only. The conductor sizes herein apply to both aluminum and Where a ladder or ventilated trough cable tray having a copper conductors. usable inside depth of 150 mm (6 in.) or less contains (A) Any Mixture of Cables. Where ladder or ventilated multiconductor control and/or signal cables only, the sum trough cable trays contain multiconductor power or lighting of the cross-sectional areas of all cables at any cross section cables, or any mixture of multiconductor power, lighting, shall not exceed 50 percent of the interior cross-sectional control, and signal cables, the maximum number of cables area of the cable tray. A depth of 150 mm (6 in.) shall be shall conform to the following: used to calculate the allowable interior cross-sectional area (1) Where all of the cables are 410 AWG or larger, the sum of any cable tray that has a usable inside depth of more than of the diameters of all cables shall not exceed the cable 150 mm (6 in.). tray width, and the cables shall be installed in a single layer. Where the cable ampacity is determined accord- (C) Solid Bottom Cable Trays Containing Any Mixture. ins to 392.11(A)(3), the cable tray width shall not be Where solid bottom cable trays contain multiconductor less than the sum of the diameters of the cables and the Power or lighting cables, or any mixture of multiconductor sum of the required spacing widths between the cables. power, lighting, control, and signal cables, the maximum (2) Where all of the cables are smaller than 410 AWG, the number of cables shall conform to the following: sum of the cross-sectional areas of all cables shall not (1) Where all of the cables are 4/0 AWG or larger, the sum exceed the maximum allowable cable fill area in Col- of the diameters of all cables shall not exceed 90 per- umn 1 of Table 392.9 for the appropriate cable tray cent of the cable tray width, and the cables shall be width. installed in a single layer. (3) Where 4/0 AWG or larger cables are installed in the (2) Where all of the cables are smaller than 4/0 AWG, the same cable tray with cables smaller than 410 AWG, the sum of the cross-sectional areas of all cables shall not Table 392.9 Allowable Cable Fill Area for Multiconductor Cables in Ladder, Ventilated Trough, or Solid Bottom Cable Trays for Cables Rated 2000 Volts or Less Maximum Allowable Fill Area for Multiconductor Cables Ladder or Ventilated Trough Cable Trays, 392.9(A) Solid Bottom Cable Trays, 392.9(C) Column 3 Column 1 Applicable for Column 4° Inside Width of Applicable for Column 2° 392.9(C)(2) Applicable for 392.9(C)(3) Cable Tray 392.9(A)(2) Only Applicable for 392.9(A)(3) Only Only Only mm in. mm2 in.Z rn1112 in.I mmz in.I mmZ in.2 150 6.0 4,500 7.0 4,500 .(30 Sd)h 7-(1.2 Sd)" 3,500 5.5 3,500-(25 Sdh) 5.5-Sdb 225 9.0 6,800 10.5 6,800 (30 Sd) 10.5-(1.2 Sd) 5,100 8.0 5,100-(25 Sd) 8.0-Sd 300 12.0 9,000 14.0 9,000-(30 Sd) 14- (1.2 Sd) 7,100 11.0 7,100-(25 Sd) I1.0-Sd 450 18.0 13.500 21.0 13,500-(30 Sd) 21-(1.2 Sd) 10,600 16.5 10,600-(25 Sd) 16.5-Sd 600 24.0 18,000 28.0 18,000-(30 Sd) 28-(1.2 Sd) 14,200 22.0 14,200-(25 Sd) 22.0-Sd 750 30.0 22500 35.0 22,500-(30 Sd) 35-(1.2 Sd) 17,700 27.5 17,700-(25 Sd) 27.5-Sd 9W 36.0 27,000 42.0 27.000-(30 Sd) 42--(1.2 Sd) 21,300 33.0 21,300-(25 Sd) 33.0-Sd "The maximum allowable fill areas in Columns 2 and 4 shall be calculated. For example,the maximum allowable fill in mm' for a 150-mm wide cable tray in Column 2 shall be 4500 minus(30 multiplied by Sd) [the maximum allowable till, in square inches, for a 6-in. wide cable tray in Column 2 shall be 7 minus(1.2 multiplied by Sd)]. "The term Sd in Columns 2 and 4 is equal to the sum of the diameters, in mm, of all cables 107.2 mm (in inches, of all 410 AWG) and larger multiconductor cables in the same cable tray with smaller cables. 70-232 NATIONAL ELECCRICAI.CODE 2(X)8 Edition ARTICLE 392—CABLE TRAYS 392.10 exceed the maximum allowable cable fill area in Column Table 392.9(E) Allowable Cable Fill Area for Multiconductor 3 of Table 392.9 for the appropriate cable tray width. Cables in Ventilated Channel Cable Trays for Cables Rated (3) Where 410 AWG or larger cables are installed in the 2000 Volts or Less same cable tray with cables smaller than 410 AWG, the Maximum Allowable Fill Area for sum of the cross-sectional areas of all cables smaller Multiconductor Cables than 4/0 AWG shall not exceed the maximum allowable fill area resulting from the computation in Column 4 of Column 2 Table 392.9 for the appropriate cable tray width.The 410 Inside Width of Column 1 More Than AWG and larger cables shall be installed in a single layer, Cable Tray One Cable One Cable and no other cables shall be placed on them. mm in. mm in.2 mm in.2 (D) Solid Bottom Cable Tray — Multiconductor Con- 75 3 1500 2.3 850 1.3 trol and/or Signal Cables Only. Where a solid bottom 100 4 2900 4.5 1600 2.5 cable tray having a usable inside depth of 150 mm(6 in.)or 150 6 4500 7.0 2450 3.8 less contains multiconductor control and/or signal cables only, the sum of the cross-sectional areas of all cables at Table 392.9(F) Allowable Cable Fill Area for Multiconductor any cross section shall not exceed 40 percent of the interior Cables in Solid Channel Cable Trays for Cables Rated 2000 cross-sectional area of the cable tray. A depth of 150 mm Volts or Less (6 in.) shall be used to calculate the allowable interior cross-sectional area of any cable tray that has a usable Column 2 inside depth of more than 150 mm (6 in.). Inside Width of Column 1 More Than Cable Tray One Cable One Cable (E) Ventilated Channel Cable 'Days. Where ventilated channel cable trays contain multiconductor cables of any mm in. mm2 in.2 turn in.2 type, the following shall apply: 50 2 850 1.3 500 0.8 (1) Where only one multiconductor cable is installed, the 75 3 1300 2.0 700 1.1 cross-sectional area shall not exceed the value specified 100 4 2400 3.7 1400 2.I in Column I of Table 392.9(E). 150 6 3600 5.5 2100 3.2 (2) Where more than one multiconductor cable is installed, the sum of the cross-sectional area of all cables shall not (1} Where all of the cables are 1000 kcmi/ or larger, the exceed the value specified in Column 2 of Table 392.9(E). sum of the diameters of all single-conductor cables shall not exceed cable tray width, and the cables shall (F) Solid Channel Cable Trays. Where solid channel be installed in a single layer. Conductors that are bound cable trays contain multiconductor cables of any type, the together to comprise each circuit group shall be permit- following shall apply: ted to be installed in other than a single layer. (1) Where only one multiconductor cable is installed, the (2) Where all of the cables are from 250 kcmil tbrough 900 cross-sectional area of the cable shall not exceed the kcmil, the sum of the cross-sectional areas of all single- value specified in Column 1 of Table 392.9(F). conductor cables shall not exceed the maximum allow- (2) Where more than one multiconductor cable is installed, able cable fill area in Column 1 of Table 392.10(A) for the sum of the cross-sectional area of all cable shall not the appropriate cable tray width. exceed the value specified in Column 2 of Table 392.9(F). (3) Where 1000 kcmiI or larger single-conductor cables are installed in the same cable tray with single-conductor 392.10 Number of Single-Conductor Cables, Rated cables smaller than 1DDD kcmi/, the sum of the cross- 2000 Volts or Less, in Cable Trays.The number of single- Sectional areas of all cables smaller than 100D kcmi/ conductor cables, rated 2000 volts or less, permitted in a single cable tray section shall not exceed the requirements shall not exceed the maximum allowable fill area re- of this section.The single conductors, or conductor assem- sulting from the computation in Column 2 of Table blies, shall be evenly distributed across the cable tray. The 392.10(A) for the appropriate cable tray width. conductor sizes herein apply to both aluminum and copper (4) Where any of the single conductor cables are 1/0 through conductors. 4/0 AWG,the sum of the diameters of all single conductor cables shall not exceed the cable tray width. (A) Ladder or Ventilated Trough Cable Trays. Where ladder or ventilated trough cable trays contain single- (B) Ventilated Channel Cable Trays. Where 50 mm conductor cables, the maximum number of single conduc- (2 in.), 75 mm (3 in.), 100 mm (4 in.), or 150 mm (6 in.) tors shall conform to the following: wide ventilated channel cable trays contain single- 2006 Edition NATIONAL ELECTRICAL CODE 70-233 392.1 l ARTICLE 392-CABLE TRAYS Table 392.10(A) Allowable Cable Fill Area for Single-Conductor Cables in Ladder or Ventilated Trough Cable Trays for Cables Rated 2000 Volts or Less Maximum Allowable Fill Area for Single-Conductor Cables in Ladder or Ventilated Trough Cable Trays Column 1 Column 28 Inside Width of Cable Trav Applicable for 392.10(A)(2) Only Applicable for 392.10(A)(3) Only mm in. mm in.2 mm2 in.2 150 6 4,200 6.5 4,200-(28 Sd)" 6.5 -0.1 Sd)" 225 9 6J00 9.5 6,100-(28 Sd) 9.5 -0.1 Sd) 3(X) 12 8,400 13.0 8,400-(28 Sd) 13.0-(1.1 Sd) 450 18 12,600 19.5 12,600-(28 Sd) 19.5 -(1.I Sd) 600 24 16,800 26.0 16,800- (28 Sd) 26.0- (1.I Sd) 750 30 21,000 32.5 21,000- (29 Sd) 32.5 - (1.1 Sd) 900 36 25,200 39.0 25,200-(28 Sd) 39.0-(I.1 Sd) 'The maximum allowable fill areas in Column 2 shall be calculated. For example,the maximum allowable fill,in mm2, for a 150 mm wide cable tray in Column 2 shall be 4200 minus(28 multiplied by Sd) [the maximum allowable 611,in square inches, for a 6-in, wide cable tray in Column 2 shall be 6.5 minus (1.1 multiplied by Sd)]. 'The term Sd in Column 2 is equal to the sum of the diameters, in mm, of all cables 507 mm' (in inches, of all 1000 kcmil) and larger single-conductor cables in the same ladder or ventilated trough cable tray with small cables. conductor cables, the sum of the diameters of all single (B) Single-Conductor Cables. The allowable ampacity of conductors shall not exceed the inside width of the channel. single-conductor cables shall be as permitted by 310.15(A)(2). The derating factors of 310.15(B)(2)(a) shall 392.11 Ampacity of Cables,Rated 2000 Volts or Less,in not apply to the ampacity of cables in cable trays. The Cable Trays. ampacity of single-conductor cables, or single conductors (A) Multiconductor Cables. The allowable ampacity of cabled together (triplexed, quadruplexed, etc.), nominally multiconductor cables, nominally rated 2000 volts or Iess, rated 2000 volts or less, shall comply with the following: installed according to the requirements of 392.9 shall be as (1) Where installed according to the requirements of given in Table 310.16 and Table 310.18, subject to the 392.10, the ampacities for 600 kcmil and larger single- provisions of(1), (2), (3), and 310.15(A)(2). conductor cables in uncovered cable trays shall not ex- (1) The derating factors of 310.15(B)(2)(a) shall apply ceed 75 percent of the allowable ampacities in Table only to multiconductor cables with more than three 310.17 and Table 310.19. Where cable trays are con- current-carrying conductors. Derating shall be limited tinuously covered for more than 1.8 m (6 ft) with solid to the number of current-carrying conductors in the unventilated covers, the ampacities for 600 kcmil and cable and not to the number of conductors in the cable larger cables shall not exceed 70 percent of the allow- troy. able ampacities in Table 310.17 and Table 310.19. (2) Where cable trays are continuously covered for more (2) Where installed according to the requirements of than 1.8 m (6 ft) with solid unventilated covers, not 392.I0, the ampacities for 110 AWG through 500 kcmil over 95 percent of the allowable ampacities of Table single-conductor cables in uncovered cable trays shall 3I0.16 and Table 310.18 shall be permitted for multi- not exceed 65 percent of the allowable ampacities in conductor cables. Table 310.17 and Table 310.19. Where cable trays are (3) Where multiconductor cables are installed in a single continuously covered for more than 1.8 m(61'11)with solid unventilated covers, the ampacities for 110 AWG through layer in uncovered trays, with a maintained spacing of 500 kcmil cables shall not exceed 60 percent of the allow- able ampacities in Table 310.17 and Table 310.14. ampacity shall not exceed the allowable ambient temperature-corrected ampacities of multiconductor (3) Where single conductors are installed in a single layer cables, with not more than three insulated conductors in uncovered cable trays, with a maintained space of rated 0 through 2000 volts in free air, in accordance not less than one cable diameter between individual with 310.15(C). conductors,the ampacity of 110 AWG and larger cables shall not exceed the allowable ampacities in Table FPN: See Table B.310.3. 310.17 and Table 310.19. 70-234 NATIONAL FLECPRICAL CODE 20()8 Edition ARTICLE 394—CONCEALED KNOB-AND-TUBE WIRING 394.2 Exception to (B)(3): For solid bottom cable trays the am- more than 95 percent of the allowable ampacities of parity of single conductor cables shall be determined by Table 310.75 and Table 310.76 shall be permitted for 310.15(C). multiconductor cables. (4) Where single conductors are installed in a triangular or (2) Where multiconductor cables are installed in a single square configuration in uncovered cable trays, with a layer in uncovered cable trays, with maintained spacing maintained free airspace of not less than 2.15 times one of not less than one cable diameter between cables, the conductor diameter (2.15 x O.D.) of the largest con- ampacity shall not exceed the allowable ampacities of ductor contained within the configuration and adjacent Table 310.71 and Table 310.72. conductor configurations or cables, the ampacity of 110 AWG and larger cables shall not exceed the allowable (B) Single-Conductor Cables (2001 Volts or Over). The ampacities of two or three single insulated conductors ampacity of single-conductor cables, or single conductors rated 0 through 2000 volts supported on a messenger in cabled together (triplexed, quadruplexed, etc.), shall com- accordance with 310.15(B). ply with the following: FPN: See Table 310.20. (1) The ampacities for 1l0 AWG and larger single- (C) Combinations of Multiconductor and Single- conductor cables in uncovered cable trays shall not ex- Conductor Cables. Where a cable tray contains a combi- reed 75 percent of the allowable ampacities in Table nation of multiconductor and single-conductor cables, the 310.69 and Table 310.70. Where the cable trays are allowable ampacities shall be as given in 392.11(A) for covered for more than 1.8 m(6 ft)with solid unventilated multiconductor cables and 392.11(B) for single-conductor covers, the ampacities for 110 AWG and larger single- cables, provided that the following conditions apply: conductor cables shall not exceed 70 percent of the allow- (I) The sum of the multiconductor cable fill area as a per- able ampacities in Table 310.69 and Table 310.70. centage of the allowable fill area for the tray calculated (2) Where single-conductor cables are installed in a single per 392.9, and the single-conductor cable fill area as a layer in uncovered cable trays,with a maintained space percentage of the allowable fill: area for the tray calcu- of not less than one cable diameter between individual lated per 392.10, totals not more than 100 percent. conductors,the ampacity of 110 AWG and larger cables (2) Multiconductor cables are installed according to 392.9 shall not exceed the allowable ampacities in Table and single-conductor cables are installed according to 310.69 and Table 310.70. 392.10 and 392.8(D) and (E). (3) Where single conductors are installed in a triangular or 392.12 Number of Type MV and Type MC Cables(2001 square configuration in uncovered cable trays, with a Volts or Over)in Cable Trays.The number of cables rated maintained free air space of not less than 2.15 times the 2001 volts or over permitted in a single cable tray shall not diameter (2.15 x O.D.) of the largest conductor con- exceed the requirements of this section. tained within the configuration and adjacent conductor The sum of the diameters of single-conductor and mul- configurations or cables, the ampacity of 110 AWG and ticonductor cables shall not exceed the cable tray width, larger cables shall not exceed the allowable ampacities and the cables shall be installed in a single layer. Where in Table 310.67 and Table 310.68, single conductor cables are triplexed, quadruplexed, or bound together in circuit groups, the sum of the diameters of the single conductors shall not exceed the cable tray width, and these groups shall be installed in single layer arrangement. ARTICLE 394 392.13 Ampacity of Type MV and Type MC Cables Concealed Knob-and-Tube Wiring (2001 Volts or Over) in Cable Trays. The ampacity of cables, rated 2001 volts, nominal, or over, installed accord- 1. General ing to 392.12 shall not exceed the requirements of this section. 394.1 Scope. This article coven the use, installation, and (A) Multiconductor Cables (2001 Volts or Over). The construction specifications of concealed knob-and-tube wiring. allowable ampacity of multiconductor cables shall be as 394.2 Definition. given in Table 310.75 and Table 310.76, subject to the following provisions: Concealed Knob-and-'lobe Wiring. A wiring method us- (1) Where cable trays are continuously covered for more ing knobs, tubes, and flexible nonmetallic tubing for the than 1.8 m (6 ft) with solid unventilated covers, not protection and support of single insulated conductors. 2008 Edition NATIONAL ELECTRICAL COVE 70-235 394.10 ARTICI.E 394—CONCEALFI) KNOB-AND-TUBE WIRING II. Installation holes in floor joists, studs, or rafters. Where run through 394.10 Uses Permitted. Concealed knob-and-tube wiring bored holes, conductors in the joists and in studs or rafters shall be permitted to be installed in the hollow spaces of to a height of not less than 2.1 m (7 ft) above the floor or walls and ceilings, or in unfinished attics and roof spaces as floor joists shall be protected by substantial running boards provided by 394.23, only as follows: extending not less than 25 mm (1 in.) on each side of the conductors. Running boards shall be securely fastened in (1) For extensions of existing installations place. Running boards and guard strips shall not be re- (2) Elsewhere by special permission quired where conductors are installed along the sides of 394.12 Uses Not Permitted. Concealed knob-and-tube joists, studs, or rafters. wiring shall not be used in the following: (B) Not Accessible by Stairway or Permanent Ladder. (1) Commercial garages Conductors shall be installed along the sides of or through (2) Theaters and similar locations bored holes in floor joists, studs, or rafters. (3) Motion picture studios Exception: In buildings completed before the wiring is in- (4) Hazardous (classified) locations stalled, attic and roof spaces that are not accessible by (5) Hollow spaces of walls, ceilings, and attics where such stairway or permanent ladder and have headroom at all spaces are insulated by loose, rolled, or foamed-in- paints less than 900 mm (3 ft), the wiring shall be permitted place insulating material that envelops the conductors to be installed on the edges of rafters or joists facing the attic or roof space. 394.17 Through or Parallel to Framing Members. Con- 394.30 Securing and Supporting. ductors shall comply with 398.17 where passing through holes in structural members. Where passing through wood (A) Supporting. Conductors shall be rigidly supported on cross members in plastered partitions, conductors shall be noncombustible, nonabsorbent insulating materials and protected by noncombustible, nonabsorbent, insulating shall not contact any other objects. Supports shall be in- tubes extending not less than 75 mm (3 in.) beyond the stalled as follows: wood member. (1) Within 150 mm (6 in.) of each side of each tap or splice, and 394.19 Clearances. (2) At intervals not exceeding 1.4 m (41/2 ft). (A) General. A clearance of not less than 75 mm (3 in.) Where it is impracticable to provide supports, conduc- shall be maintained between conductors and a clearance of tors shall be permitted to be fished through hollow spaces not less than 25 mm (I in.) between the conductor and the in dry locations, provided each conductor is individually surface over which it passes. enclosed in flexible nonmetallic tubing that is in continuous (B) Limited Conductor Space.Where space is too limited lengths between supports, between boxes, or between a to provide these minimum clearances, such as at meters, support and a box. panelboards, outlets, and switch points, the individual con- (B) Securing. Where solid knobs are used, conductors ductors shall be enclosed in flexible nonmetallic tubing, shall be securely tied thereto by tie wires having insulation which shall be continuous in length between the last sup- equivalent to that of the conductor. port and the enclosure or terminal point. {C} Clearance from Piping, Exposed Conductors, and 394.42 Devices. Switches shall comply with 404.4 and 404.10(B). So Forth. Conductors shall comply with 398.19 for clear- ances from other exposed conductors, piping, and so forth. 394.56 Splices and Taps. Splices shall be soldered unless approved splicing devices are used. In-line or strain splices 394.23 In Accessible Attics. Conductors in unfinished at- shall not be used. tics and roof spaces shall comply with 394.23(A) or (B). FPN: See 3 10.10 for temperature limitation of conductors. III. Construction Specifications (A) Accessible by Stairway or Permanent Ladder. Con- 394.104 Conductors. Conductors shall be of a type speci- ductors shall be installed along the side of or through bored fied by Article 310. 70-236 NATIONAL.ELECTRICAL CODE 2008 Edition ARTICLE 398—OPEN WIRING ON INSULATORS 398.2 Table 396.10(A) Cable Types ARTICLE 396 Messenger-Supported Wiring Cable Type Section Article Medium-voltage cable 328 I. General Metal-clad cable 330 Mineral-insulated, 332 396.1 Scope. This article covers the use, installation, and metal-sheathed cable Multiconductor 338 construction specifications for messenger-supported wiring, service-entrance cable Multiconductor underground 340 396.2 Definition. Feeder and branch-circuit cable Messenger-Supported Wiring.An exposed wiring support Other factory-assembled, system using a messenger wire to support insulated conduc- multiconductor control, signal, or power cables that tors by any one of the following: are identified for the use (1) A messenger with rings and saddles for conductor sup- Power and control tray cable 336 port Power-limited tray cable 725.154(C) and (2) A messenger with a field-installed lashing material for 725.179(E) conductor support 396.30 Messenger. (3) Factory-assembled aerial cable (4) Multiplex cables utilizing a bare conductor, factory as- (A) Support. The messenger shall be supported at dead ends and at intermediate locations so as to eliminate tension sembled and twisted with one or more insulated con- on the conductors.The conductors shall not be permitted to ductors, such as duplex, triplex, or quadruplex type of come into contact with the messenger supports or any construction structural members, walls, or pipes. 11. Installation (B) Neutral Conductor.Where the messenger is used as a neutral conductor,it shall comply with the requirements of 396.10 Uses Permitted. 225.4, 250.184(A),2:50.184(B)(7), and 250.186(H). (A) Cable Types.The cable types in Table 396.10(A)shall (G) Equipment Grounding Conductor. Where the mes- be permitted to be installed in messenger-supported wiring senger is used as an equipment grounding Conductor, it under the conditions described in the article or section ref- shall comply with the requirements of 250.32(B),250.118, erenced for each. 250.184(B)(8), and 250.186(D). (B) In Industrial Establishments. In industrial estab- 396.56 Conductor Splices and Taps. Conductor splices lishments only,where conditions of maintenance and super- and taps made and insulated by approved methods shall be vision ensure that only qualified persons service the in- permitted in messenger-supported wiring. stalled messenger-supported wiring, the following shall be permitted: 396.60 Grounding. The messenger shall be grounded as (1) Any of the conductor types shown in Table 310.13(A) required by 250.80 and 250.86 for enclosure grounding. or Table 310.13(B) (2) MV cable Where exposed to weather, conductors shall be listed ARTICLE 398 for use in wet locations. Where exposed to direct rays of the sun, conductors or cables shall be sunlight resistant. Open Wiring on Insulators (C) Hazardous (Classified) Locations. Messenger- I. General supported wiring shall be permitted to be used in hazardous (classified)locations where the contained cables are permit- 398.1 Scope. This article covers the use, installation, and ted for such use in 501.10, 502.10, 503.10, and 504.20. construction specifications of open wiring on insulators. 396.12 Uses Not Permitted. Messenger-supported wiring 398.2 Definition. shall not be used in hoistways or where subject to physical Open Wiring on insulators. An exposed wiring method damage. using cleats, knobs, tubes, and flexible tubing for the 2008 Edition NATIONAL ELECTRICAL CODE 70-237 398.10 ARTICLE 398—OPEN WIRING ON INSULATORS protection and support of single insulated conductors run in tecting vertical conductors on side walls, the boxing or on buildings, shall be closed at the top and the holes through which the conductors pass shall be bushed. II. Installation (4) Rigid metal conduit, intermediate metal conduit, rigid nonmetallic conduit, or electrical metallic tubing. 398.10 Uses Permitted.Open wiring on insulators shall be When installed in metal piping, the conductors shall be permitted only for industrial or agricultural establishments encased in continuous lengths of approved flexible on systems of 600 volts, nominal, or less, as follows: tubing. (1) Indoors or outdoors (2) In wet or dry locations 398.17 Through or Parallel to Framing Members. Open conductors shall be separated from contact with walls, {3) Where subject to corrosive vapors floors, wood cross members, or partitions through which {4) For services they pass by tubes or bushings of noncombustible, nonab- sorbent insulating material, Where the bushing is shorter 398.12 Uses Not Permitted. Open wiring on insulators than the hole, a waterproof sleeve of naninductive material shall not be installed where concealed by the building shall be inserted in the hole and an insulating bushing structure. slipped into the sleeve at each end in such a manner as to 398.15 Exposed Work. keep the conductors absolutely out of contact with the sleeve. Each conductor shall be carried through a separate (A) Dry Locations. In dry locations, where not exposed to tube or sleeve. physical damage, conductors shall be permitted to be sepa- FPN: See 310.10 for temperature limitation of conductors. rately enclosed in flexible nonmetallic tubing. The tubing p shall be in continuous lengths not exceeding 4.5 m (15 ft) 398.19 Clearances. Open conductors shall be separated at and secured to the surface by straps at intervals not exceed- least 50 mil (2 in.) from metal racewa 5 i in or other ing 1.4 m (4t/ ft). conducting material,and from any exposed lighting,power, (B) Entering Spaces Subject to Dampness, Wetness, or or signaling conductor, or shall be separated therefrom by a Corrosive Vapors. Conductors entering or leaving loca- continuous and firmly fixed nonconductor in addition to the tions subject to dampness, wetness, or corrosive vapors insulation of the conductor. Where any insulating tube is shall have drip loops formed on them and shall then pass used, it shall be secured at the ends. Where practicable, upward and inward from the outside of the buildings, or conductors shall pass over rather than under any piping from the damp, wet, or corrosive location, through non- subject to leakage or accumulations of moisture. combustible, nonabsorbent insulating tubes. 398.23 In Accessible Attics. Conductors in unfinished at- FPN: See 230.52 for individual conductors entering build- tics and roof spaces shall comply with 398.23(A) or (B). ings or other structures. (A) Accessible by Stairway or Permanent Ladder. Con- (C) Exposed to Physical Damage. Conductors within 2.1 m ductors shall be installed along the side of or through bored (7 ft) from the floor shall be considered exposed to physical holes in floor joists, studs, or rafters. Where run through damage. Where open conductors cross ceiling joists and wall bored holes, conductors in the joists and in studs or rafters studs and are exposed to physical damage, they shall be pro- to a height of not less than 2.I m (7 ft) above the floor or tected by one of the following methods: floor joists shall be protected by substantial running boards (1) Guard strips not less than 25 mm (1 in.) nominal in extending not less than 25 mm (I in.) on each side of the thickness and at least as high as the insulating supports, conductors. Running boards shall be securely fastened in placed on each side of and close to the wiring. place. Running boards and guard strips shall not be re- (2) A substantial running board at least 13 mm (t/2 in.) quired for conductors installed along the sides of joists, thick in back of the conductors with side protections. studs, or rafters. Running boards shall extend at least 25 mm (I in.) outside the conductors, but not more than 50 mm (B) Not Accessible by Stairway or Permanent Ladder. (2 in.), and the protecting sides shall be at least 50 mm Conductors shall be installed along the sides of or through (2 in.) high and at least 25 mm (1 in.), nominal, in bared hales in floor joists, studs, or rafters. thickness. Exception: In buildings completed before the wiring is in- (3) Boxing made in accordance with 398.15(C)(1) or stalled, in attic and roof spaces that are not accessible by (C)(2) and furnished with a cover kept at least 25 mm stairway or permanent ladder and have headroom at till (1 in.) away from the conductors within. Where pro- points less than 900 nun(3 ft), the wiring.shall he permitted 70238 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 398—OPEN WIRING ON INSULATORS 398.104 to be installed on the edges of rafters or joists facing the (C) Industrial Establishments. In industrial establish- attic or roof space. ments only, where conditions of maintenance and supervi- sion ensure that only qualified persons service the system, 398.30 Securing and Supporting. conductors of sizes 250 kcmil and larger shall be permitted (A) Conductor Sizes Smaller Than 8 AWG. Conductors to be run across open spaces where supported at intervals smaller than 8 AWG shall be rigidly supported on noncom- up to 9.0 m (30 ft) apart. bustible, nonabsorbent insulating materials and shall not (D) Mounting of Conductor Supports. Where nails are contact any other objects. Supports shall be installed as used to mount knobs, they shall not be smaller than ten- follows: penny. Where screws are used to mount knobs, or where (1) Within I50 mm (6 in.) from a tap or splice nails or screws are used to mount cleats, they shall be of a (2) Within 300 mm (12 in.) of a dead-end connection to a length sufficient to penetrate the wood to a depth equal to at lampholder or receptacle least one-half the height of the knob and the full thickness (3) At intervals not exceeding 1.4 m (4'/2 ft) and at closer of the cleat. Cushion washers shall be used with nails. intervals sufficient to provide adequate support where likely to be disturbed (E) Tie Wires.Conductors 8 AWG or larger and supported on solid knobs shall be securely tied thereto by tie wires (B) Conductor Sizes 8 AWG and Larger. Supports for having an insulation equivalent to that of the conductor. conductors 8 AWG or larger installed across open spaces shall be permitted up to 4.5 m (15 ft) apart if noncombus- 398.42 Devices. Surface-type snap switches shall be tible, nonabsorbent insulating spacers are used at least ev- mounted in accordance with 404.10(A), and boxes shall not ery 1.4 m (4'/2 ft) to maintain at least 65 mm (21/2 in.) be required. Other type switches shall be installed in accor- between conductors. dance with 404.4. Where not likely to be disturbed in buildings of mill construction, 8 AWG and larger conductors shall be permit- III. Construction Specifications ted to be run across open spaces if supported from each wood cross member on approved insulators maintaining 398.104 Conductors. Conductors shall be of a type speci- 150 mm (6 in.) between conductors. fied by Article 310. 2008 Edition NATIONAL ELECTRICAL CODE 70-239 CHAPTER 4 ARTICLE 4(x4—FLEXIBLE CORDS AND CABLES Chapter 4 Equipment for General Use 400.3 Suitability. Flexible cords and cables and their as- ARTICLE 400 sociated fittings shall be suitable for the conditions of use Flexible Cords and Cables and location. 400.4 Types. Flexible cords and flexible cables shall con- I. General form to the description in Table 400.4. Types of flexible 400.1 Scope. This article covers general requirements, ap- cords and flexible cables other than those listed in the table plications, and construction specifications for flexible cords shall be the subject of special investigation. and flexible cables. 400.2 Other Articles. Flexible cords and flexible cables shall comply with this article and with the applicable pro- visions of other articles of this Code. Table 400.4 Flexible Cords and Cables (See 400.4.) Nominal Insulation Thickness' AWG Number A'WG Braid Trade Type or or or on Each Outer Name Letter Voltage kcmil Conductors Insulation kcmil nun mils Conductor Covering Use lamp C 3110 18-16 2 or more Themmyset 18-16 0.76 30 Comm None Pendant or 1)ry Nix card Wo 14-10 orthenno• 14-10 1.14 45 portable kxa• hard plauic tinm usngc Eletalor E 3t N1 or 20-2 2 or more Thermout 20-16 0.51 20 Colton Three cotton. Elevator Unclamititd cable See Note 7. 6110 14-12 0.76 311 Outer tine lighting and kwaliom Ste Note H. 12-10 1 14 45 Harm- control Sk Now 12 tt-« 1.52 60 retardant& moisture- resklani. Ste Now 5. 21)-]6 11.51 20 Flexible 14-12 11.76 30 nylon 12-10 1.14 45 jacket 8-2 1.52 611 Elcvautt FO 3IK1 or 21 2 2 or more Thermoset 20-16 0.51 211 Conon Omer one Elevator Unclassillld cable See Note 7. NX1 14-12 0.76 30 Three collun, lighting and location% See Note 12. 12-10 1.14 45 flame- cuntrul 8-2 1.52 641 retardant& muisture- resiswi. Ste Note 5. One cotton and H varduus a neoprene HA%silitdl jacket lrw atinns Sec Note 5. Elevator ETP 34x1 or Rayon Thermo- Hazardous(classiliedl ltkauons cable See Note 7_ 61K1 plastic See NOW 12. Err IM or None One cotton or Ste Note 7. UK) equivalent and See NOW 12. a thermtr plastic jacket 70-240 NATIONAL ELECTRICAL CODF 2008 Edition ARTICLE 400-FLEXIBLE CORDS AND CABLES 400.4 I'able 400.4 Coudymed Nominal Insulation Thickness' ANVC Number AWG Braid Trade Tape or or or on Each Outer Name Leifer Voltage kcmit Conducturs Insulation kcmll mm mils Conductor Covering Use Electric UV 69X) III-51X1 2 or more Thennrnet Il~16 0.76({1511 3l)(20) Optional Thermowt Electric Wet Extra Vehicle Sce Note plus with 14-10 114(0.76) 45(30) vehicle location, hard cable 13. grounding Optional F-2 1.52(1.14) 60(45) charging usage conduclorls), nylon See 1-110 203(1.52) 80(60) plus optional Note 14, 250500 2.41 (1.9(1) 95(75) hybrid Bala. See Note 14. signal communi- cations,and optical fiber cable,% EVJ 3{X) 19 12 INr12 0.76(0.51) 30(20) yard Ste Note See Noic 14, usage 13. EVE 600 18-51X) 2 or more Thermo- 03-16 0.76(1.51) .10 120) TherrnoPlastic Extra wx Now plus plastic 14-18 1.14((1.761 45(30) elustomer hard 13. grounding claslomer 8-2 1.52 11.14) 60(451 usage conduclorls), with I-I10 2.03(1.52) 80(601 plus npuonal optional 2,51E 241(1.9)) 95(751 hvhnd data, nylon See 51X) See Nole 14. signal Note 14. communi- cation~,and optical fiber cable's EVJE 3'xl ]8-12 18-12 0.76(o.51) 30(201 Hard See Note See Note 14. usage 13. EVT 2 or mare Thermo- 18-16 0.76(0.51) 30(20) Optional Thennopluslic Electric Wet Extra See Now plus plastic with 14-10 1.14(0.76) 45(30) vehicle Locations hard 13, grounding optional 8-2 1.52(1.14) (,(1(49) charging usage conduclorls), nylon See I-4A) 2.01(152) 13111601 plug optional Noic 14. 250- 2.41 (1.90) 95(7.5) hvhnd data, 5011 See Note 14. signal communi- cations,and Optical fiber Cables EVJT 31X) 19-12 I8 12 t 0.76 30(20) Hard See Note (0.51) Sce Note 14. usage l3. Portable G 24XXI I2-51X1 2-h Plus Therrru»el 12-2 1.52 60 Oil-resistant Portable and extra hard wage power grounding 1-1!(7 2.03 80 thermoset cable conduclurM 250-51X1 2.41 95 G-GC 2(XX) 12-5M 3-6 plus Thermoset 12-2 1.52 60 Oil-resistant Wounding 1-11) 2.01 80 thermoset conductors 250-5M 2.41 95 and ground check conductor Hcater HPD 3{X) 18-12 2,3,or 4 Therniowl 18-16 0.314 15 None COl[ln Or Portable Dry Not coal 14-12 11.76 30 rayon heaters Irxa- hard boas usage (Conrinfrei f 2008 Edition NATIONAL ELECTRICAL CODE 70-241 400.4 ARTICLE 400--FLEXIBLE CORDS ARID CABLES Table 400.4 Continued Nominal Insulation Thickness' AWG Number AWG Brow Trade Type or or or on Each Outer Name Letter Voltage kcmll Conductors Imid Lion kcmil mm mils Conductor Covering Use Parallel HPN 300 18-12 2 or 3 Oil-resistant 18-16 1.14 45 None Oil-resistant Portable Damp Not heater See Note 8. thermoset 14-12 152 60 thermoset locations hard cord 2,41 95 usage Thermoset HSJ 300 18-12 2,3,or 4 Thermoset 18-16 0.76 30 None Cotton and Portable or Damp Hard jacketed 14-12 1.14 45 Thermoset portable Iota- usage heater healer tions; cords HSJO 300 18-12 Cotton and oil-resistant thermoset HSJOO 300 18-12 Oil-resistant thermoset Non- NISP-1 I 300 20-18 2 or 3 Themumt 2J-IS 0.38 i5 None Thermoset Pendant or Damp Not integral portable Iota- hard parallel NISP-2 300 18-16 18-16 0,76 30 tions usage cord% NISPE-1 300 20-18 Thermo- 218 0.38 15 -thermoplastic See Note S. plastic elastomer elastomer NISPE-2 300 18-16 18-16 036 30 See Note 8. NISPT-1 3t)0 20-18 Thermo- 20-18 0.38 15 Thermoplastic See Note H. plastic NISPT-2 300 18-16 18-16 0.76 30 See Note 8. Twisted PI) 300 18-16 2 or more Thermoset 18-16 0.76 30 Cotton Cotton or Pendant or Dr} Not portable 600 14-10 orthermo- 14-10 1.14 45 rayon portable loca- hard cord plastic lions usage Portable PPE 2000 12-500 1-6 plus Thermo- 12-2 152 60 Oil-resistant Portable,extra hard usage power optional plastic 1-4/0 203 80 thermoplastic cable grounding elastomer 250-500 2.41 95 elastomer conductor(s) Hard S 600 18-12 2 or more Thermoset ig-16 0.76 30 None Thermoset Pendant or Damp Extra .service See Note 6. Will 1.14 45 portable Iota- hard cord l 8-2 1.52 60 lions usage Flexible SC 601) 8-250 1 or more 8-2 1.52 60 Thermoset" Portable,extra hard usage stage and 1-310 2.03 80 lighting 250 2.41 95 power cable SCE 600 Thermo- Thermoplastic plastic elastomer' elastomer SCT 600 Thermo- 7hcrra plastic plastic° Hard SE 600 18-2 2 or mote Thenno- 18-16 0.76 30 None Thermoplastic Pendant or Damp Extra service Sce Note 6. plastic 14-10 1.14 45 elastomer portable loca- hard cord elaslomer 8-2 1.52 60 tions usage SEW 600 Damp See Note 6. and wet See Note 15. locations SEO 6W Oil-resistant Damp See Note 6. themtoplastic Itxalioas elastomer 70-242 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 400—FLEXIBLE CORDS AND CABLES 400,4 Table 400.4 Continued Nominal Insulation Thickness' AWU ;Number AWG Braid Trade T`tpe or of or on Each Outer Name Letter Volluge kcmil Conductors Irauialion kemii mm mils Conductor Covering Use SEOW 6(x) Dam See Now 6. p and wet See Note 15. locations SEW See 6W Oil-resktani Damp Note 6. therirxr locations pla%tic SEDOW 601 clamorer Dam See Note 6. P and wet See Note 15, 1=60M Junior hand SJ 3(x1 IK-IU 2-6 Thermoset 111-12 6.76 311 None Thermoset Pendant or Damp Hard service portable loca• usage uml tinns SJE 3(x1 Thermo- Thermoplastic plastic elasutmer clastomer SEW Wl Sep-Note 15. Damp and wet locations SJEO 1(x1 Oil- Damp resistant kcatiom thermoplastic elastomer SJEOW 1(x1 See Note 15. Damp and wet locations SJEOO 1(x1 Oil-resistant Damp thermo Irx:atioas p1;c%tic eiauomer SJEOOW 3(x) See Note 15. Damp and wet location% S1O 31M1 Thermoset Oil-resistant Damp thermoset locations SJOW 1(x1 Sex Note 15. Damp and wet locations SJOO 3(x1 Oil-resistant Damp thenna e[ IUCatimn,% SJ()E)W 3(x1 Six Note 15. Damp and wet locations SIT 31x1 Thermo- 16 1.14 45 Thenmpla%tic Damp plastid' locations SJTW 3IX1 Sex Note IS. Damp and we[ lcadoms (Continues) 2(H)8 Edition NATIONAL ELECTRICAL CODL 70-243 400.4 ARTICLE 400—FLEXIBLE CORDS AND CABLES Table 400.4 Continued `ondnal Insulation Thickness' AWG Number ANVG Braid Trade Type or of or on Each Outer Name Letter Voltage kemil Conductors Insulation kcmil mm mils Conductor Covering Use Junior harts SJTO 300 19-10 2-6 Thermo- 18-12 (1.76 30 None Oil- Pendant or Damp Hard .service plastic resistant portable locations usage cord tltermo- (rant.) lastic SJTOW 300 Damp See Note 15. and wet locations SJTOO 300 Oil-resistant Damp therno- locations Plastic SJTOOW 300 Damp See Note 15. and wet locadom Hard SO 600 18-2 2 or more Thermoset 1"6 0.76 30 None Oil-resistant Pendant or Damp Extra service See Note 6. thermoset portable loca- hard cord lions usage SOW 60() Damp See Note 6. and wet See Now 15. locations SOO 600 Oil- 14-10 1.14 45 Damp Sec Note 6. resistant 8-2 1.52 60 IDLU60ns thermoset SOOW 600 Damp See Note 6. and wet See Note 15. Ioeatimns All SP-1 300 20-18 2 or 3 Therrnoset 20-18 0.76 30 Now None Pendant or Damp Not thermoset portable loca- bard parallel lions wage cord SP-2 300 18-16 18-16 1.14 1 45 SP-3 300 18-10 18-16 1.52 60 Refriger- 14 2.03 80 ators,mom 12 2.41 95 air condition- 10 2.80 110 ers,and as permitted in 422.16(B) All SPE-I 300 20-18 2 or 3 Thermo- 20-18 0.76 30 None None Pendant or Damp Not elastomer See Note S. plastic portable loca- Hard (thermo- elaatorner lions usage plastic) parallel curd SPE-2 300 18-16 18-16 1.14 45 See Note&. SPE-3 300 18-10 18-16 IS2 60 Refrigera- See Nate 8. 14 2,03 80 ton,room 12 2.41 95 air condition- l0 2.80 Ito ers,and as permitted in 422,16(H) All plastic SPT-1 300 20-18 2 or 3 Thermo- 20-18 0,76 30 None None Pendant or Damp Not parallel plastic pmnable loca. hard cord tans usage SPT-I W 300 2 Damp See Note 15. and wet locations 70-244 NATIONAL ELECTRICAL,CODE 2008 Edition ARTICLE 400—FLEXIBLE CORDS AND CABLES 400.4 Table 400.4 Continued Nominnl Insulation Thickness' AWG Number AWG Braid Trade Type or of or on Each Outer Name Letter Voltage kcmil Conductors Insulation kemil mm mils Conductor Covering use SIT-2 3110 18-16 2os3 18-16 1.14 45 Damp locations SPT2W 3t1[! 2 Damp See Now 15, and wet locations SPT 3 31X1 1&-10 2 or 3 18-16 1.52 60 Rc&iger Damp Not 14 103 80 ators,norm loca- hand 12 2.41 95 air buns usage 10 180 1i0 conditionem and as permitted in 422.[6181 Range. SRD Son 10-4 3 or 4 Thermoset 10--4 1.14 45 None Thermoset Portable Damp Ranges. dryer loca. dryers cable Loss SRDE 31Md 10--4 3 or 4 Thernki- None Thermoplastie plastic elastomer elastomer SRDT 31X1 It" 3 or Thermo- None Thermoplastic plastic Hard ST 600 18-2 2 or mare Themmo- 18-16 0.76 31! None Thermoplastic Pendant or Damp Extra service See Now 6. plastic 14-10 1.14 45 punal>)e Iota- hard cord 8-2 1.52 60 dorms usage STW 6ax! See Note 6. Damp and wet See Note 15. 1 locations STO 61X1 Oil-reSistant Damp See Note 6. thermoplastic locations STOW 6110 Sec Note 6. Damp and wet See Note 15. Iox:ations STOO 6011 Oil-resistant Damp See Note 6. themes- locations plastic STOOW 6110 Damn See Note 6, p and locations Vacuum SV 31X1 18-16 2 or 3 Tltemtoset 18-16 0.38 0 None Thermoset Pendant or Damp Not cleaner porwhlc loca- hard cord lions usage SVE 31X1 Thermo- Themwplauic piastie elastomer elastomer SVEO 3(X1 Oil-resistant thermoplastic elastomer SVEOO I00 Oil-m%istanl thermo- plastic elastomer (Continue s) 2008 Edition NATIONAL ELECTRICAL CODE 70-245 400.4 ARTICLE 400---FLEXIBLE CORDS AND CABLES Table 400.4 Continued Nominal Insulation Thickness' AWG Number AWG Braid Trade Type or of or on Each Outer Name Letter Valtage kemll Conductors Insulation kcmil mm mils Conductor Covering Use Vacuum SVO 300 18-16 2 or 3 Thermoset 18-16 0.38 15 None Oil-resistant Pendant or Damp Not cleaner thermoset portable locations hard cord usage frronr.l SVOO 3110 Oil-nnslstant Oil.resistant thennoict thermoset SVT 300 Thermo- Themraplastie plastic SVTO 3(X1 Thermo- Oil-resistant plastic thermoplastic SVTOO 300 Oil-resistant thermo- plastic Parallel TPT 300 27 2 Thermo- 27 0.76 30 None Thermoplastic Attached to Damp Not tinsel See Note 4. plastic an appliance Ima- hard cord lions usage Juckcied TST 300 27 2 Thermo- 27 U.38 15 None Thermoplastic Attached to Damp Not tinsel See Note 4. plastic an appliance loca- hard coat Limns usage Portable W 2000 12-500 1-6 Thermoset 12-2 1.52 61) Oil-resistant Portable,extra hard usage power- 501-1000 1 1-110 2.03 80 thertoset cable 291-500 2.41 95 501-1(X1) 2.80 110 Notes: 'See Note S. 'The required outer covering on some single-conductor cables may be integral with the insulation. ;AII types listed in Table 400.4 shall have individual conductors twisted together except for Types HPN,SP-I,SP-2,SP-3,SPE-1,SPE-2,SPE-3,SPT-1,SPT-2,SPT-3, TPT,NISP-l.NISP-2,NISPT-1,NISPT-2,NISPE-1.NISPE-2,and three-conductor parallel versions of$RD.SRDE,and SRDT. 4Types TPT and TST shall be permitted in lengths not exceeding 2.5 m(S ft)where attached directly,or by means of a special type of plug,to a portable appliance rated at 50 watts or less and of such nature that extreme flexibility of the cord is essential. ;Rubber-tilled or varnished cambric tapes shall be permitted as a substitute for the inner braids. '"1'ypes G,G-GC,S.SC,SCE,SCT,SE,SEO,SE00,SO,SOO,ST,STO,STOO,PPE,and W sball be permitted for use on theater stages,in garages,and elsewhere where flexible cards are permitted by this Code. 7Elevator traveling cables for operating control and signal circuits shall contain nonmetallic fillers as necessary to maintain concentricity.Cables shall have steel supporting members as required for suspension by 62U.41. In locations subject to excessive moisture or corrosive vapors or gases, supporting members of other materials shall be permitted-Where sled supporting members are used,they shall run straight through the center of the cable assembly and shall not be cabled with the copper strands of any conductor. In addition to conductors used for control and signaling circuits,Types E,EO,EPP,and EIT elevator cables shall be permitted to incorporate in the construction one or more 20 AWG telephone conductor pairs,one or more coaxial cables,or one or more optical fibers.The 20 AWG conductor pairs shall he permitted to be covered with suitable shielding for telephone,audio,or higher frequency communications circuits_the coaxial cables consist of a center conductor,insulation,and shield for use in video or other radio frequency communications circuits.The optical fiber shall be suitably covered with flame-retardant thermoplastic,The insulation of the conductors shall be rubber or thermoplastic of thickness not less than specified for the other conductors of the particular type of cable.Metallic shields shall have their own protective covering.Where used,these components shall be permitted to be incorporated in any layer of the cable assembly but shall not run straight through the center. "The third conductor in Type HPN shall he used aS an equipment-rounding conductor only.The insulation of the equipment grounding conductor for Types SPE-1, SPE-2,SPE-3,SPT-1,SPT-2,SPT-3,NISPT-1,NISPT-2,NISPE-1,and NISPE-2 shall be permitted to be thermoset polymer. gThe individual conductors of all curds,except those of heal-resistant cords,-ball have a thermoset or thermoplastic insulation,except that the equipment grounding conductor where used shall be in accordance with 400.23(B)• 1OWhere the vahagc between any two conductors exceeds 301,but does not exceed 600,flexible cord of 10 AWG and smaller shall have thermoset or thermoplastic insulation on the individual conductors at least 1.14 mm(45 mils)in thickness,unless Type S,SE,SEO,SHOO,SO,SOO,ST.STO,or STOO card is used. "Insulation and outer coverings that meet the requirements as flame retardant,limited smoke,and are so listed,shall he permitted to be marked for limited smoke after the code type designation. I'laevator cables in sizes 20 AWG through 14 AWG are rated 300 volts,and sizes 10 through 2 are rated 600 volts. 12 AWG is rated 300 volts with a 0.76-mm (30-nail)insulation thickness and 601 volts with a 1.14-mm(45-mil)insulation thickness. '`Conductor size for Types EV, EVJ, EVE, EVJE, EVT,and EVJT cables apply to nonpower-limned circuits only. Conductors of power-limited (data, signal,or communications)circuits may extend beyond the stated AWG size range.All conductors shall be insulated for the same cable voltage rating. [¢Insulation thickness for Types EV,EVJ,EVWE,EVT,and EVJT cables of nylon construction is indicated in parentheses. i s Cords Ihut comply with the requirements for outdoor cords and are so listed shall be permitted to be designated as weather and water resistant with the suffix"W" after the code type designation. Cords with the"W"suffix are suitable for use in wet locations. 70-246 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 4W—FLEXIBLE CORDS AND CABLES 400.7 400.5 Ampacities for Flexible Cords and Cables. Exception: For other loading conditions, adjustment Jac- (A) Ampacity Tables. Table 400.5(A) provides the allow- tors shall he permitted to he calculated tender 310.15(C). able ampacities, and Table 400.5(B) provides the ampaci- FPN: See Annex B,Table B.310.11, for adjustment factors ties for flexible cords and cables with not more than three for more than three current-carrying conductors in a race- current-carrying conductors. These tables shall be used in way or cable with load diversity. conjunction with applicable end-use product standards to 400.6 Markings. ensure selection of the proper size and type. Where cords are used in ambient temperatures exceeding 30°C (86°F), (A) Standard Markings. Flexible cords and cables shall the temperature correction factors from Table 310.16 that be marked by means of a printed tag attached to the coil correspond to the temperature rating of the cord shall be reel or carton. The tag shall contain the information re- applied to the ampacity from Table 400.5(8). Where the quired in 310.11(A). Types S, SC, SCE, SCT, SE, SEO, number of current-carrying conductors exceeds three, the SEGO, SJ, SJE, SJEO, SJEOO, SJO, SJT, SJTO, SJTOO, allowable ampacity or the ampacity of each conductor shall SO, SOO, ST, STO, STOO, SEW, SEOW, SEOOW, SJEW, be reduced from the 3-conductor rating as shown in Table SJEOW, SJEOOW, SJOW, SJTW, SJTOW, SJTOOW, 400.5. SOW, SOOW, STW, STOW, and STOOW flexible cords Table 400.5 Adjustment Factors for More Than Three and G, G-GC, PPE, and W flexible cables shall be durably Current-Carrying Conductors in a Flexible Cord or Cable marked on the surface at intervals not exceeding 610 mm (24 in.) with the type designation, size, and number of Number Percent of Value in Tables conductors. of Conductors 400.5(A) and 400.5(B) (B) Optional Markings. Flexible cords and cable types 4--6 80 listed in Table 400.4 shall be permitted to be surface 7–g 70 marked to indicate special characteristics of the cable ma- 10–20 50 terials. These markings include, but are not limited to, 21 –30 45 g'markin s for limited smoke, sunlight resistance, and so 31 –40 40 g 41 and above 35 forth. (B) Ultimate Insulation Temperature. In no case shall 400.7 Uses Permitted. conductors be associated together in such a way with re- (A) Uses. Flexible cords and cables shall be used only for spect to the kind of circuit, the wiring method used, or the the following: number of conductors such that the limiting temperature of (1) Pendants the conductors is exceeded. A neutral conductor that carries only the unbalanced (2) Wiring of luminaires current from other conductors of the same circuit shall not (3) Connection of portable luminaires, portable and mo- be required to meet the requirements of a current-carrying bile signs, or appliances conductor. (4) Elevator cables In a 3-wire circuit consisting of two phase conductors (5) Wiring of cranes and hoists and the neutral conductor of a 4-wire, 3-phase, wye- (6) Connection of utilization equipment to facilitate fre- connected system, a common conductor carries approxi- quent interchange mately the same current as the line-to-neutral currents of (7) Prevention of the transmission of noise or vibration the other conductors and shall be considered to be a (8) Appliances where the fastening means and mechani- current-carrying conductor. cal connections are specifically designed to permit On a 4-wire, 3-phase, wye circuit where more than 50 percent of the load consists of nonlinear loads, there are ready removal for maintenance and repair, and the harmonic currents present in the neutral conductor and the appliance is intended or identified for flexible cord connection neutral conductor shall be considered to be a current- carrying conductor. (9) Connection of moving parts An equipment grounding conductor shall not be consid- (10) Where specifically permitted elsewhere in this Code ered a current-carrying conductor. Where a single conductor is used for both equipment (B) Attachment Plugs. Where used as permitted in 400.7(A)(3), (A)(6), and (A)(8), each flexible cord shall be grounding and to carry unbalanced current from other con- equipped with an attachment plug and shall be energized doctors, as provided for in 250.140 for electric ranges and from a receptacle outlet. electric clothes dryers, it shall not be considered as a current-carrying conductor. Exception: As permitted in 368.56. 2008 Edition NATIONAL ELECTRICAL CODE 70_247 400.8 ARTICLE 400---FLEXIBLE CORDS AND CABLES Table 400.5(A) Allowable Ampacity for Flexible Cords and Cables [Based on Ambient Temperature of 30°C (86°F). See 400.13 and Table 400.4.1 Thermoset Types C, E, EO,PD,S,SJ,S.IO,SJOW, SJOO,SJOOW, SO, SOW, SOO,SOOW, SP-1, SP-2, SP-3,SRD, SV, SVO,SVOO Thermoplastic Types ET,ETLB, ETP, ETT, SE,SEW, SEO,SEOW, SEOOW,SJE,SJEW,SJEO, SJEOW, SJEOOW,SJT,SJTW,SJTO,SJTOW, SJTOO, SJTOOW,SPE-1,SPE-2,SPE-3,SPT 1, SPT=1W, Thermoplastic SPT-2,SPT 2W,SPT-3,ST,SRDE,SRDT, STO,STOW, Types HPD, HPN, Size (AWG) Types TPT,TST STOO,STOOW,SVE,SVEO,SVT,SVTO,SVTOO HSJ, HSJO,HSJOO Column A+ Column B* 27* 0.5 — — — 20 — 5** *** — l8 — 7 10 l0 17 — 9 12 13 16 — 10 13 15 15 — 12 16 17 14 — 15 l8 20 12 — 20 25 30 10 — 25 30 35 8 — 35 40 — 6 — 45 55 — 4 -- 60 70 — 2 — 80 95 — *Tinsel cord. **Elevator cables only. ***7 amperes for elevator cables only;2 amperes For other types. +The allowable currents under Column A apply to 3-conductor cords and other multiconductor cords connected to utilization equipment so that only 3 conductors are current-carrying. The allowable currents under Column B apply to 2-conductor cords and other multiconductor cords connected to utilization equip- ment so that only 2 conductors are current-carrying. 400.8 Uses Not Permitted. Unless specifically permitted column in Table 400.4) 14 AWG and larger shall be Per- in 400.7, flexible cords and cables shall not be used for the mitted if conductors are spliced in accordance with following: 110.14(B) and the completed splice retains the insulation, (1) As a substitute for the fixed wiring of a structure outer sheath properties, and usage characteristics of the (2) Where run through holes in walls, structural ceilings, cord being spliced. suspended ceilings, dropped ceilings, or floors (3) Where run through doorways, windows, or similar 400.10 Pull at Joints and Terminals. Flexible cords and openings cables shall be connected to devices and to fittings so that (4) Where attached to building surfaces tension is not transmitted to joints or terminals. Exception to(4): Flexible card and cable shall be permitted Exception: Listed portable single-pole devices that are in- to be attached to building surfaces in accordance with the tended to accommodate such tension at their terminals provisions of 368.56(B) shall be permitted to be used with single-conductor flexible (5) Where concealed by walls, floors,or ceilings or located cable. above suspended or dropped ceilings FPN: Some methods of preventing pull on a cord from being (6) Where installed in raceways, except as otherwise per- transmitted to joints or terminals are knotting the cord,wind- mitted in this Cade ing with tape,and fittings designed for the purpose. (7) Where subject to physical damage 400.11 In Show Windows and Showcases. Flexible cords 400.9 Splices. Flexible cord shall be used only in continu- used in show windows and showcases shall be Types S, SE, ous lengths without splice or tap where initially installed in SEO, SEGO, SJ, SJE, SJEO, SJEOO, SJO, SJOO, SJT, applications permitted by 400.7(A). The repair of hard- SJTO, SJTOO, SO, SOO, ST, STO, STOO, SEW, SEOW, service cord and junior hard-service cord (see Trade Name SEOOW, SJEW, SJEOW, SJEOOW, SJOW, SJOOW, 70-248 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 400—FLEXIBLE CORDS AND CABLES 400.14 Table 400.5(B) Ampacity of Cable Types SC,SCE,SCT, PPE, G, G-GC,and W. (Based on Ambient Temperature of 30°C (86°F). See Table 400.4.] Temperature Rating of Cable Size 60°C (140°F) 75°C (167°F) 90°C (1947) (AWG or kcmil) Dt EZ F' Dt Ez F3 D' EZ Fa 12 — 31 26 — 37 31 — 42 35 10 — 44 37 --- 52 43 — 59 49 8 60 55 48 70 65 57 80 74 65 6 80 72 63 95 88 77 105 99 87 4 105 96 84 125 115 101 140 130 114 3 120 113 99 145 135 118 165 152 133 2 140 128 112 170 152 133 190 174 152 1 165 150 131 195 178 156 220 202 177 110 195 173 151 230 207 181 260 234 205 210 225 199 174 265 238 208 300 271 237 310 260 230 201 310 275 241 350 313 274 410 300 265 232 360 317 277 405 361 316 250 340 296 259 405 354 310 455 402 352 300 375 330 289 445 395 346 505 449 393 350 420 363 318 505 435 381 570 495 433 400 455 392 343 545 469 410 615 535 468 500 515 448 392 620 537 470 700 613 536 600 575 — — 690 — — 780 — — 700 630 — — 755 — — 855 — — 750 655 — — 785 — — 885 — — 800 680 — — 815 — — 920 — 900 730 — — 870 — — 985 — 1000 780 — — 935 -- — 1055 -- — 'The ampacities under subheading D shall be permitted for single-conductor Types SC,SCE,SCT,PPE,and W cable only where the individual conductors are not installed in raceways and are not in physical contact with each other except in lengths not to exceed 600 mm (24 in.) where passing through the wall of an enclosure. 2The ampacities under subheading E apply to two-conductor cables and other muiticonductor cables con- nected to utilization equipment so that only two conductors are current-carrying. ;The ampacities under subheading F apply to three-conductor cables and other multiconductor cables con- nected to utilization equipment so that only three conductors are current-carrying. SJTW, SJTOW, SJTOOW, SOW, SOOW, STW, STOW, or use with specific appliances, shall be considered as pro- STOOW, tected against overcurrent by the overcurrent devices de- Exception No. 1: For the iviring of chain-supported scribed in 240.5. luminaires. 400.14 Protection from Damage. Flexible cords and Exception No. 2: As .supply cords for portable luminaires cables shall be protected by bushings or fittings where pass- and other merchandise being displayed or exhibited. ing through holes in covers, outlet boxes, or similar enclo- sures. 400.12 Minimum Size. The individual conductors of a In industrial establishments where the conditions of flexible cord or cable shall not be smaller than the sizes in maintenance and supervision ensure that only qualified per- Table 400.4. sons service the installation, flexible cords and cables shall Exception: The size of the insulated ground-check conduc- be permitted to be installed in aboveground raceways that for of Type G-GC cables shall be not smaller than 10 AWG. are no longer than 15 m (50 ft) to protect the Flexible cord or cable from physical damage. Where more than three 400.13 Overcurrent Protection. Flexible cords not current-carrying conductors are installed within the race- smaller than IS AWG, and tinsel cords or cords having way, the allowable ampacity shall be reduced in accordance equivalent characteristics of smaller size approved for with Table 400.5. 2009 Edition NATIONAL ELECTRICAL CODE 70-249 400.20 ARTICLE 400—FLEXIBLE CORDS AND CABLES 11. Construction Specifications insulation on the individual conductors integral with the 400.20 Labels. Flexible cords shall be examined and jacket. tested at the factory and labeled before shipment. (E) Tinned Conductors. One conductor having the indi- vidual strands tinned and the other conductor or conductors 400.21 Nominal Insulation Thickness. The nominal having the individual strands untinned for cords having thickness of insulation for conductors of flexible cords and insulation on the individual conductors integral with the cables shall not be less than specified in Table 400.4. jacket. Exception: The nominal insulation thickness for the (F) Surface Marking. One or more ridges, grooves, or ground-check conductors of Type G-GC cables shall not be white stripes located on the exterior of the cord so as to less than 1.14 mm (45 mils)for 8 AWG and not less than identify one conductor for cords having insulation on the 0.76 mm (30 rnits)for 10 AWG. individual conductors integral with the jacket. 400.22 Grounded-Conductor Identification, One con- 400.23 Equipment Grounding Conductor Identifica- ductor of flexible cords that is intended to be used as a tion. A conductor intended to be used as an equipment grounded circuit conductor shall have a continuous marker grounding conductor shall have a continuous identifying that readily distinguishes it from the other conductor or marker readily distinguishing it from the other conductor or conductors. The identification shall consist of one of the conductors. Conductors having a continuous green color or methods indicated in 400.22(A) through (F), a continuous green color with one or more yellow stripes shall not be used for other than equipment grounding con- (A) Colored Braid. A braid finished to show a white or ductors. The identifying marker shall consist of one of the gray color and the braid on the other conductor or conduc- methods in 400.23(A) or (B), tors finished to show a readily distinguishable solid color or colors. (A) Colored Braid.A braid finished to show a continuous green color or a continuous green color with one or more (B) Tracer in Braid. A tracer in a braid of any color con- yellow stripes. trasting with that of the braid and no tracer in the braid of the other conductor or conductors. No tracer shall be used (B) Colored Insulation or Covering. For cords having no in the braid of any conductor of a flexible cord that contains braids on the individual conductors, an insulation of a Ion- a conductor having a braid finished to show white or gray. sinuous green color or a continuous green color with one or Exception: In the ease of Types C and AD and cords hav- more yellow stripes. ing the braids on the individual conductors finished to show 400.24 Attachment Plugs. Where a flexible cord is pro- white or gray. In such cords, the identifying marker shall be vided with an equipment grounding conductor and permitted to consist of the solid white or gray finish on one equipped with an attachment plug, the attachment plug conductor,provided there is a colored tracer in the braid of shall comply with 250.138(A) and (B). each other conductor. (C) Colored Insulation.A white or gray insulation on one III. Portable Cables Over 600 Volts, Nominal conductor and insulation of a readily distinguishable color or colors on the other conductor or conductors for cords 400.30 Scope. Part HI applies to multiconductor portable having no braids on the individual conductors. cables used to connect mobile equipment and machinery. For jacketed cords furnished with appliances, one con- ductor having its insulation colored light blue, with the 400.31 Construction. other conductors having their insulation of a readily distin- (A) Conductors. The conductors shall be 12 AWG copper guishable color other than white or gray. or larger and shall employ flexible stranding. Exception: Cords that have insulation on the individual conductors integral with the jacket. (B) Shields. Cables operated at over 2000 volts shall be shielded. Shielding shall be for the purpose of confining the The insulation shall be permitted to be covered with an voltage stresses to the insulation. outer finish to provide the desired color. (C) Equipment Grounding Conductor(s). An equipment (D) Colored Separator. A white or gray separator on one grounding conductor(s) shall be provided. The total area conductor and a separator of a readily distinguishable solid shall not be less than that of the size of the equipment color on the other conductor or conductors of cords having grounding conductor required in 250.122. 70-250 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 402—FIXTURE WIRES 402,3 400.32 Shielding. All shields shall be connected to an equipment grounding conductor. ARTICLE 402 400.33 Equipment Grounding Conductors. Equipment Fixture Wires grounding conductors shall be connected in accordance with Parts VI and VII of Article 250. 402.1 Scope. This article covers general requirements and construction specifications for fixture wires. 400.34 Minimum Bending Radii. The minimum bending radii for portable cables during installation and handling in 402.2 Other Articles. Fixture wires shall comply with this service shall be adequate to prevent damage to the cable. article and also with the applicable provisions of other ar- ticles of this Code. 400.35 Fittings. Connectors used to connect lengths of FPN: For application in luminaires, see Article 410. cable in a run shall be of a type that locks firmly together. Provisions shall be made to prevent opening or closing 402.3 Types.Fixture wires shall be of a type listed in Table these connectors while energized. Suitable means shall be 402,3, and they shall comply with all requirements of that used to eliminate tension at connectors and terminations. table.The fixture wires listed in Table 402.3 are all suitable for 400.36 Splices and Terminations. Portable cables shall service at 600 volts, nominal, unless otherwise specified, not contain splices unless the splices are of the permanent FPN: Thermoplastic insulation may stiffen at temperatures molded, vulcanized types in accordance with 110.14(B). colder than-10°C(+14°F),requiring that care be exercised Terminations on portable cables rated over 600 volts, norm- during installation at such temperatures. Thermoplastic in- sulation may also be deformed at normal temperatures nal, shall be accessible only to authorized and qualified where subjected to pressure, requiring that care be exer- personnel. cised during installation and at points of support. Table 402.3 Fixture Wires Thickness of Insulation Maximum 7r'pe Outer Operating Application Name Letter Insulation AWG mm mils Covering Temperature Provisions Heat-resistant FFH-2 Heat-resistant 18-16 0.76 30 Nonmetallic 75°C Fixture wiring rubber- rubber covering 167°F covered Cross-linked 18-16 0.76 30 fixture wire — flexible synthetic stranding polymer ECTFE— HF Ethylene 18-14 0.38 15 None 150°C Fixture wiring solid or 7- chlorotri- 302°F strand fluoroethylene ECTFE— HFF Ethylene 18-14 0.38 15 None 150°C Fixture wiring flexible chlorotriflu- 302°F stranding oroethylene Tape insulated KF-i Aromatic 18-10 0.14 5.5 None 200°C Fixture wiring fixture wire polyimide 392°F —limited to —solid or tape 300 volts 7-strand KF-2 Aromatic 18-10 0.21 8.4 None 200°C Fixture wiring polyimide 392°F tape Tape insulated KFF-I Aromatic 18--10 0.14 5.5 None 200°C Fixture wiring fixture wire polyimide 392°F —limited to --- flexible tape 300 volts stranding KFF-2 Aromatic 18-10 0.21 8.4 None 200°C Fixture wiring polyimide 392°F tape (Continues) 2008 Edition NATIONAL ELECTRICAL CODE 70-251 402.3 ARTICLE 402—FIXTURE WIRES Table 402.3 Continued Thickness of Insulation Maximum Type Outer Operating Application Name Letter Insulation AWG mm mils Covering Temperature Provisions Perfiuoro- PAF Perfluoro- 18-14 0.51 20 None 250°C Fixture wiring alkoxy — alkoxy 482°F (nickel or solid or 7- nickel-coated strand copper) (nickel or nickel-coated copper) Perfiuoro-alkoxy PAFF Perfiuoro- 18-14 0.51 20 None 150°C Fixture wiring — flexible alkoxy 302°F stranding Fluorinated PF Fluorinated 18-14 0.51 20 None 200°C Fixture wiring ethylene ethylene 392°F propylene propylene fixture wire —solid or 7-strand Fluorinated PFF Fluorinated 18-14 0.51 20 None 150°C Fixture wiring ethylene ethylene 302°F propylene propylene fixture wire —flexible stranding Fluorinated PGF Fluorinated 18-14 0.36 14 Glass braid 200°C Fixture wiring ethylene ethylene 392°F propylene propylene fixture wire —solid or 7-strand Fluorinated PGFF Fluorinated 18--14 0.36 14 Glass braid 150°C Fixture wiring ethylene ethylene 302°F propylene propylene fixture wire — flexible stranding Extruded PTF Extruded 18-14 0.51 20 None 250°C Fixture wiring polytetraflu- polytetraflu- 482°F (nickel or oroethylene oroethylene nickel-coated —solid or copper) 7-strand (nickel or nickel-coated copper) 70-252 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 402—FIXTURE WIRES 402.3 Table 402.3 Continued Thickness of Insulation Maximum Type Outer Operating Application Name Letter Insulation AWG mm mils Covering Temperature Provisions Extruded PTFF Extruded 18-14 0.51 20 None 150°C Fixture wiring polytetraflu- polytetraflu- 302°F (silver or oroethylene oroethylene nickel-coaled ---- flexible copper) stranding 26-36 (AWG silver or nickel- coated copper) Heat-resistant RFH-I Heat-resistant 18 0.38 15 Nonmetallic 75°C Fixture wiring rubber- rubber covering 167°F —limited to covered 300 volts fixture wire —solid or RFH-2 Heat-resistant 18-16 0.76 30 [done or non- 75°C Fixture wiring 7-strand rubber metallic 167°F Cross-linked covering synthetic polymer Heat-resistant RFHH-2* Cross-linked 18-16 0.76 30 [None or non- 90°C Fixture wiring cross-linked synthetic metallic 194°F — synthetic polymer covering polymer-insu- I aced fixture wire RFHH-3* 18--16 1.14 45 —solid or 7- strand Silicone SF-1 Silicone 18 0.38 15 Nonmetallic 200°C Fixture wiring insulated rubber covering 392°F —limited to fixture wire 300 volts —Solid or 7-strand SF-2 Silicone 18--12 0.76 30 Nonmetallic 200°C Fixture wiring rubber 10 1.14 45 covering 392°F Silicone SFF-I Silicone 18 0.38 15 Nonmetallic 150°C Fixture wiring insulated rubber covering 302°F — limited to fixture wire 300 volts -- flexible stranding SFF-2 Silicone 18--12 0.76 30 Nonmetallic 150°C Fixture wiring rubber 10 1.14 45 covering 302' Thermoplastic TF* Thermoplastic 18-16 0.76 30 None 60°C Fixture wiring covered 140°F fixture wire —solid or 7-strand Thermoplastic TFF* Thermoplastic 18-16 0.76 30 None 60°C Fixture wiring covered 140°F fixture wire --flexible stranding (Continues) 2008 Edition NATIONAL ELECTRICAL CODE 70-,253 402.3 ARTICLE 402—FIXTURE WIRES Table 402.3 Continued Thickness of Insulation Maximum Type Outer Operating Application Name Letter Insulation AWG mm mils Covering Temperature Provisions Heat-resistant TFN* Thermoplastic 18-16 0.38 15 Nylon-jacket- 90°C Fixture wiring thermo- ed or 194°F plastic equivalent covered fixture wire —solid or 7-strand Heat-resistant TFFN* Thermoplastic 18--16 0.38 15 Nylon jacket- 90°C Fixture wiring thereto- ed or 194°F Plastic equivalent covered fixture wire — flexible stranded Cross-linked XF* Cross-linked 18-14 0.76 30 None 15WC Fixture wiring polyolefin polyolefin 12-10 1.14 45 302°F — limited to insulated 300 volts fixture wire —solid or 7-strand Cross-linked XFF* Cross-linked 18-14 0.76 30 None 150°C Fixture wiring polyolefin polyolefin 12-10 1.14 45 302°F --limited to insulated 300 volts fixture wire ---flexible stranded Modified ETFE ZF Modified 18-14 0.38 15 None 150°C Fixture wiring ---solid or ethylene 302°F 7- strand tetrafluoro- ethylene Flexible ZFF Modified 18-14 0.38 15 None 150°C Fixture wiring stranding ethylene 302°F tetrafluoro- ethylene High temp. ZHF Modified 18-14 0.38 15 None 200°C Fixture wiring modified ethylene 392°F ETFE— tetrafluoro- solid or 7- ethylene strand *Insulations and outer coverings that meet the requirements of flame retardant, limited smoke, and are so listed shall be permitted to be marked for limited smoke after the Code type designation. 70-254 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 404—SWITCHES 404.3 402.5 Allowable Ampacities for Fixture Wires. The al- 402.12 Overcurrent Protection. Overcurrent protection lowable ampacity of fixture wire shall be as specified in for fixture wires shall be as specified in 240.5. Table 402.5. No conductor shall be used under such conditions that its operating temperature exceeds the temperature specified in Table 402.3 for the type of insulation involved. FFN: See 310.10 for temperature limitation of conductors. ARTICLE 404 SW1tC}1CS Table 402.5 Allowable Ampacity For Fixture Wires Size (AWG) Allowable Ampacity 1. Installation 18 6 404.1 Scope. The provisions of this article shall apply to 16 8 all switches, switching devices, and circuit breakers where 14 17 used as switches. 12 23 10 28 404.2 Switch Connections. 402.6 Minimum Size. Fixture wires shall not be smaller (A) Three-Way and Four-Way Switches. Three-way and than 18 AWG. four-way switches shall be wired so that all switching is done only in the ungrounded circuit conductor. Where in 402.7 Number of Conductors in Conduit or Tubing.The metal raceways or metal-armored cables, wiring between number of fixture wires permitted in a single conduit or switches and outlets shall be in accordance with 300.20(A). tubing shall not exceed the percentage fill specified in Table 1, Chapter 9. Exception: Switch loops shall not require a grounded conductor. 402.8 Grounded Conductor Identification. Fixture wires that are intended to be used as grounded conductors shall (B) Grounded Conductors. Switches or circuit breakers be identified by one or more continuous white stripes on shall not disconnect the grounded conductor of a circuit. other than green insulation or by the means described in Exception: A switch or circuit breaker shall be permitted 400.22(A) through (E). to disconnect a grounded circuit conductor where all cir- cuit conductors are disconnected simultaneously, or where 402.9 Marking. the device is arranged.so that the grounded conductor can- not be disconnected until all the ungrounded conductors of (A) Method of Marking. Thermoplastic insulated fixture the circuit have been disconnected. wire shall be durably marked on the surface at intervals not exceeding 610 mm (24 in.). All other fixture wire shall be 404.3 Enclosure. marked by means of a printed tag attached to the coil, reel, or carton. (A) General. Switches and circuit breakers shall be of the externally operable type mounted in an enclosure listed for (B) Optional Marking. Fixture wire types listed in Table the intended use. The minimum wire-bending space at ter- 402.3 shall be permitted to be surface marked to indicate minals and minimum gutter space provided in switch en- special characteristics of the cable materials. These mark- closures shall be as required in 312.6. ings include, but are not limited to, markings for limited smoke, sunlight resistance, and so forth. Exception No. 1: Pendant- and surface-type snap switches and knife switches mounted on an open face switchboard 402.10 Uses Permitted. Fixture wires shall be permitted or panelboard shall be permitted without enclosures. (1) for installation in luminaires and in similar equipment Exception No. 2: Switches and circuit breakers installed in where enclosed or protected and not subject to bending or accordance with 110.27(A)(1), (A)(2), (A)(3), or (A)(4) twisting in use, or (2) for connecting luminaires to the shall be permitted without enclosures. branch-circuit conductors supplying the luminaires. (B) Used as a Raceway. Enclosures shall not be used as 402.11 Uses Not Permitted. Fixture wires shall not be junction boxes, auxiliary gutters, or raceways for conductors used as brunch-circuit conductors except as permitted else- feeding through or tapping off to other switches or overcurrent where in the Code. devices, unless the enclosure complies with 312.8. 2008 Edition NATIONAL ELHCrRICAL CODE 70-255 404.4 ARTICLE 404—SWITCHES 404.4 Damp or Wet Locations.A surface.-mounted switch 404.7 Indicating. General-use and motor-circuit switches, or circuit breaker in a damp or wet location shall be en- circuit breakers, and molded case switches, where mounted closed in a weatherproof enclosure or cabinet that shall in an enclosure as described in 404.3, shall clearly indicate comply with 312.2. Aflush-mounted Switch or circuit whether they are in the open (off) or closed (on) position. breaker in a damp or wet location shall be equipped with a Where these switch or circuit breaker handles are oper- weatherproof cover. Switches shall not be installed within ated vertically rather than rotationally or horizontally, the wet locations in tub or shower spaces unless installed as up position of the handle shall be the (on) position. part of a listed tub or shower assembly. Exception No. 1: Vertically operated double-throw 404.5 Time Switches, Flashers, and Similar Devices. switches shall be permitted to be in the closed(on)position Time switches, flashers, and similar devices shall be of the with the handle in either the up or down position. enclosed type or shall be mounted in cabinets or boxes or Exception No. 2: On busway installations, tap switches equipment enclosures. Energized parts shall be barriered to employing a center-pivoting handle shall be permitted to be prevent operator exposure when making manual adjust- open or closed with either end of the handle in the up or ments or switching. down position. The switch position shall be clearly indicat- ing and shall be visible from the floor or from the usual Exception: Devices mounted so they are accessible only to point of operation. qualified persons shall be permitted without barriers, pro- vided they are located within an enclosure such that any 404,8 Accessibility and Grouping. energized parts within 152 mm (6.0 in.) of the manual ad justment or switch are covered by suitable barriers. (A) Location. All switches and circuit breakers used as switches shall be located so that they may be operated from 404.6 Position and Connection of Switches. a readily accessible place. They shall be installed such that the center of the grip of the operating handle of the switch (A) Single-Throw Knife Switches. Single-throw knife or circuit breaker, when in its highest position, is not more switches shall be placed so that gravity will not tend to than 2.0 m (6 ft 7 in.) above the floor or working platform. close them. Single-throw knife switches, approved for use in the inverted position, shall be provided with an integral Exception No. 1: On busway installations,fused switches mechanical means that ensures that the blades remain in the and circuit breakers shall be permitted to be located at the open position when so set. same level as the busway. Suitable means shall be provided to operate the handle of the device from the floor. (B) Double-Throw Knife Switches. Double-throw knife Exception No. 2: Switches and circuit breakers installed switches shall be permitted to be mounted so that the throw adjacent to motors, appliances, or other equipment that is either vertical or horizontal. Where the throw is vertical, they supply shall be permitted to be located higher than 2.0 m integral mechanical means shall be provided to hold the blades in the open position when so set. (6 ft in.)and to be accessible by portable means. Exception No. S: Hookstick operable isolating switches (C) Connection of Switches. Single-throw knife switches shall be permitted at greater heights. and switches with butt contacts shall be connected such that their blades are de-energized when the switch is in the open (B} Voltage Between Adjacent Devices. A snap switch position. Bolted pressure contact switches shall have barn- snap not be grouped or ganged in enclosures with other ers that prevent inadvertent contact with energized blades. snap switches, receptacles, or similar devices, unless they Single-throw knife switches, bolted pressure contact are arranged so that the voltage between adjacent devices switches, molded case switches, switches with butt contacts, does not exceed 300 volts, or unless they are installed in and circuit breakers used as switches shall be connected so enclosures equipped with identified, securely installed bar- that the terminals supplying the load are de-energized when Tiers between adjacent devices. the switch is in the open position. (C) Multipole Snap Switches. A multipole, general-use Exception: The blades and terminals supplying the load of Snap switch shall not be permitted to be fed from more than a switch shall be permitted to be energized when the switch a single circuit unless it is listed and marked as a two- is in the open position where the switch is connected to circuit or three-circuit switch,or unless its voltage rating is circuits or equipment inherently capable of providing a not less than the nominal line-to-line voltage of the system backfeed source of power. For such installations, a perma- supplying the circuits. nent sign shall be installed on the switch enclosure or im mediately adjacent to open switches with the following 404.9 Provisions for General-Use Snap Switches. words or equivalent: WARNING — LOAD SIDE TERMI- (A) Faceplates. Faceplates provided for snap switches NALS MAY BE ENERGIZED BY BACKFEED. mounted in boxes and other enclosures shall be installed so 70-256 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 404—SWITCHES 404.14 as to completely cover the opening and, where the switch is 404.11 Circuit Breakers as Switches. A hand-operable flush mounted, seat against the finished surface. circuit breaker equipped with a lever or handle, or a power- operated circuit breaker capable of being opened by hand in (B) Grounding. Snap switches, including dimmer and the event of a power failure, shall be permitted to serve as similar control switches, shall be connected to an equip- a switch if it has the required number of poles, ment grounding conductor and shall provide a means to connect metal faceplates to the equipment grounding con- FPN: See the provisions contained in 240.81 and 240.83. ductor, whether or not a metal faceplate is installed. Snap switches shall be considered to be part of an effective 404.12 Grounding of Enclosures. Metal enclosures for ground-fault current path if either of the following condi- switches or circuit breakers shall be Connected to an equip- tions is met: ment grounding conductor as specified in Part N of Article (1) The switch is mounted with metal screws to a metal 250• Metal enclosures for Switches or circuit breakers used box or metal cover that is connected to an equipment as service equipment shall comply with the previsions of grounding conductor or to a nonmetallic box with inte- Part V of Article 250. Where nonmetallic enclosures are gral means for connecting to an equipment grounding used with metal raceways or metal-armored cables, provi- conductor. Sion shall be made for connecting the equipment grounding (2) An equipment grounding conductor or equipment conductor(s). bonding jumper is connected to an equipment ground- Except as covered in 404.9(B), Exception, nonmetallic ing termination of the snap switch. boxes for switches shall be installed with a wiring method that provides or includes an equipment grounding conductor. Exception to (B): Where no means exists within the snap- switch enclosure for connecting to the equipment ground- 404.13 Knife Switches. ing conductor or where the wiring method does not include or provide an equipment grounding conductor, a stoop (A) Isolating Switches. Knife switches rated at over 1200 switch without a connection to an equipment grounding amperes at 250 volts or less, and at over 600 amperes at conductor shall be permitted for replacement purposes 251 to 600 volts, shall be used only as isolating switches only. A snap switch wired under the provisions of this and shall not be opened under load. ex- ception and located within reach of earth, grade, conduct- (B) To Interrupt Currents. To interrupt currents over ing floors, or other conducting surfaces shall be provided 1200 amperes at 250 volts, nominal, or less, or over 600 am- with a faceplate of nonconducting, noncombustible mate- peres at 251 to 600 volts, nominal, a circuit breaker or a rial or shall be protected by a ground fault circuit switch of special design listed for such purpose shall be used. interrupter. (C) Construction. Metal faceplates shall be of ferrous (C) General-Use Switches. Knife switches of ratings less than specified in 404.13(A) and (B} shall be considered metal not less than 0.76 mm (0.030 in.) in thickness or of genera]-use switches. nonferrous metal not less than 1.02 mm(0.040 in.)in thick- ness. Faceplates of insulating material shall be noncombus- FPN: See the definition of General-Use Switch in Article tible and not less than 2.54 min (0.010 in.) in thickness, but 100. they shall be permitted to be less than 2.54 mm (0.010 in.) in thickness if formed or reinforced to provide adequate (D) Motor-Circuit Switches. Motor-circuit switches shall mechanical strength. be permitted to be of the knife-switch type. FPN: See the definition of a Motor-Circuit Switch in 404.10 Mounting of Snap Switches. Article 100. (A) Surface-Type. Snap switches used with open wiring 404.14 Rating and Use of Snap Switches. Snap switches on insulators shall be mounted on insulating material that shall be used within their ratios and as indicated in separates the conductors at least 13 mm (1/z in.) from the 404.14(A) through (E), g surface wired over. FPN No. 1: For switches on signs and outline lighting,see (B) Box Mounted. Flush-type snap switches mounted in 600.6. boxes that are set back of the finished surface as permitted FPN No. 2: For switches controlling motors, see 430.83, in 314.20 shall be installed so that the extension plaster ears 430.109, and 430.110. are seated against the surface. Flush-type snap switches mounted in boxes that are flush with the finished surface or (A) Alternating-Current General-Use Snap Switch. A project from it shall be installed so that the mounting yoke form of general-use snap switch suitable only for use on ac or strap of the switch is seated against the box. circuits for controlling the following: 2008 Edition NATIONAL ELECTRICAL CODE 70-257 404.15 ARTICLE 406—RECEPTACLES,CORD CONNECTORS,AND ATTACHMENT PLUGS (CAPS) (1) Resistive and inductive loads, including electric- (B) Off Indication. Where in the off position, a switching discharge lamps,not exceeding the ampere rating of the device with a marked OFF position shall completely dis- switch at the voltage involved connect all ungrounded conductors to the load it controls. (2) Tungsten-filament lamp loads not exceeding the am- pere rating of the switch at 120 volts 404.16 600-Volt Knife Switches. Auxiliary contacts of a (3) Motor loads not exceeding 80 percent of the ampere renewable or quick-break type or the equivalent shall be rating of the switch at its rated voltage provided on all knife switches rated 600 volts and designed for use in breaking current over 200 amperes. (B) Alternating-Current or Direct-Current General-Use Snap Switch. A form of general-use snap switch suitable for 404.17 Fused Switches. A fused switch shall not have use on either ac or do circuits for controlling the following: fuses in parallel except as permitted in 240.8. (1) Resistive loads not exceeding the ampere rating of the switch at the voltage applied. 404.18 Wire-Bending Space. The wire-bending space re- (2) Inductive loads not exceeding 50 percent of the ampere quired by 404.3 shall meet Table 312.6(B) spacings to the rating of the switch at the applied voltage. Switches enclosure wall opposite the line and load terminals. rated in horsepower are suitable for controlling motor loads within their rating at the voltage applied. (3) Tungsten-filament lamp loads not exceeding the am- pere rating of the switch at the applied voltage if T-rated. ARTICLE 406 Receptacles, Cord Connectors, (C) CO/ALR Snap Switches. Snap switches rated 20 am- and Attachment Plugs (Caps) peres or less directly connected to aluminum conductors shall be listed and marked COIALR. 406.1 Scope. This article covers the rating, type, and in- (D) Alternating-Current Specific-Use Snap Switches stallation of receptacles, cord connectors, and attachment Rated for 347 Volts.Snap switches rated 347 volts ac shall plugs (cord caps). be listed and shall be used only for controlling the loads permitted by (D)(1) and (D)(2). 406.2 Receptacle Rating and Type. (1) Noninductive Loads. Noninductive loads other than tungsten-filament lamps not exceeding the ampere and volt- (A) Receptacles, Receptacles shall be listed and marked age ratings of the switch. with the manufacturer's name or identification and voltage and ampere ratings. (2) Inductive Loads. Inductive loads not exceeding the ampere and voltage ratings of the switch. Where particular (B) Rating.Receptacles and cord connectors shall be rated load characteristics or limitations are specified as a condi- not less than 15 amperes, 125 volts, or 15 amperes, 250 tion of the listing, those restrictions shall be observed re- volts, and shall be of a type not suitable for use as lam- gardless of the ampere rating of the load. pholders. The ampere rating of the switch shall not be less than 15 amperes at a voltage rating of 347 volts ac. Flush-type FPN: See 210.21(B) for receptacle ratings where installed snap switches rated 347 volts ac shall not be readily inter- on branch circuits. changeable in box mounting with switches identified in 404.14(A) and (B). (C) Receptacles for Aluminum Conductors. Receptacles rated 20 amperes or less and designed for the direct con- (E) Dimmer Switches.General-use dimmer switches shall nection of aluminum conductors shall be marked COIALR. be used only to control permanently installed incandescent luminaires unless listed for the control of other loads and (D) Isolated Ground Receptacles. Receptacles incorpo- installed accordingly. rating an isolated grounding conductor connection intended for the reduction of electrical noise (electromagnetic inter- ference) as permitted in 250.146(D) shall be identified by II. Construction Specifications an orange triangle located on the face of the receptacle. 404.15 Marking. (1) Isolated Equipment Grounding Conductor Required. (A) Ratings. Switches shall be marked with the current, Receptacles so identified shall be used only with equipment voltage, and, if horsepower rated, the maximum rating for grounding conductors that are isolated in accordance with which they are designed. 250.146(D). 70-258 NATIONAL ELECTRICAL CODE 2008 Editinn ARTICLE 406—RECEPTACLES,CORD CONNECTORS,AND ATTACHMENT PLUGS(CAPS) 406.4 (2) Installation in Nonmetallic Boxes.Isolated ground re- shall be connected to the equipment grounding conductor in ceptacles installed in nonmetallic boxes shall be covered accordance with 406.3(C) or 250.130(C). with a nonmetallic faceplate. (2) Ground-Fault Circuit Interrupters. Ground-fault Exception: Where an isolated ground receptacle is in- circuit-interrupter protected receptacles shall he provided stalled in a nonmetallic box, a metal faceplate shall he where replacements are made at receptacle outlets that are permitted if'the box contains a feature or accessory that required to be so protected elsewhere in this Code. permits the effective grounding of the faceplate. (3) Non–Grounding-Type Receptacles. Where attach- 406.3 General Installation Requirements. Receptacle ment to an equipment grounding conductor does not exist outlets shall be located in branch circuits in accordance in the receptacle enclosure, the installation shall comply with Part III of Article 210. General installation require- with (D)(3)(a), (D)(3)(b), or (D)(3)(c). ments shall be in accordance with 406.3(A) through (F). (a) A non–grounding-type receptacle(s) shall be per- mitted to be replaced with another non–grounding-type re- (A) Grounding Type.Receptacles installed on 15-and 20- ceptacle(s). ampere branch circuits shall be of the grounding type. (b) A non–grounding-type receptacle(s) shall be per- Grounding-type receptacles shall be installed only on cir- mitted to be replaced with a ground-fault circuit intemtpter- cuits of the voltage class and current for which they are type of receptacle(s). These receptacles shall be marked rated, except as provided in Table 210.2](B)(2) and Table "No Equipment Ground." An equipment grounding con- 210.21(B)(3). ductor shall not be connected from the ground-fault circuit- Exception: Nongrounding-type receptacles installed in ac- interrupter-type receptacle to any outlet supplied from the cordance with 406.3(D). ground-fault circuit-interrupter receptacle. (c) A non–grounding-type receptacle(s) shall be per- (B) To Be Grounded. Receptacles and cord connectors mitted to be replaced with a grounding-type receptacle(s) that have equipment grounding conductor contacts shall where supplied through a ground-fault circuit interrupter. have those contacts connected to an equipment grounding Grounding-type receptacles supplied through the ground- conductor: fault circuit interrupter shall be marked "GFCI Protected" and "No Equipment Ground." An equipment grounding Exception Nn. l: Receptacles mounted on portable and conductor shall not be connected between the grounding- type receptacles. Exception No. 2: Replacement receptacles as permitted b)• 406.3(D). (E) Cord-and-Plug-Connected Equipment. The installa- tion of grounding-type receptacles shall not be used as a (C) Methods of Grounding. The equipment grounding requirement that all cord-and-plug-connected equipment be conductor contacts of receptacles and cord connectors shall of the grounded type, be grounded by connection to the equipment grounding FPN: See 250.114 for types of cord-and-plug-connected conductor of the circuit supplying the receptacle or cord equipment to be grounded, connector. (F) Noninterchangeable Types. Receptacles connected to FPN: For installation requirements for the reduction of circuits that have different voltages,frequencies, or types of electrical noise, see 250.146(D). current (ac or dc) on the same premises shall be of such The branch-circuit wiring method shall include or pro- design that the attachment plugs used on these circuits are vide an equipment grounding conductor to which the equip- not interchangeable. ment grounding conductor contacts of the receptacle or cord connector are connected. 406.4 Receptacle Mounting. Receptacles shall be mounted in boxes or assemblies designed for the purpose, FPN No. 1: See 250.118 for acceptable grounding means. and such boxes or assemblies shall be securely fastened in FPN No. 2: For extensions of existing branch circuits, see place unless otherwise permitted elsewhere in this Code. 250.130. (A) Boxes That Are Set Back. Receptacles mounted in (D) Replacements. Replacement of receptacles shall com- boxes that are set back from the finished surface as permit- ply with 406.3(D)(1), (D)(2), and (D)(3) as applicable. ted in 314.20 shall be installed such that the mounting yoke (1) Grounding-Type Receptacles. Where a grounding or strap of the receptacle is held rigidly at the finished means exists in the receptacle enclosure or an equipment surface. grounding conductor is installed in accordance with (B) Boxes That Are Flush. Receptacles mounted in boxes 250.130(C), grounding-type receptacles shall be used and that are flush with the finished surface or project therefrom 2008 Edition NATIONAL ELECTRICAL CODE 70-259 406.5 ARTICLE 406—RECEPTACLES,CORD CONNECTORS,AND ATTACHMENT`PLUGS (CAPS) shall be installed such that the mounting yoke or strap of (A) Construction of Attachment Plugs and Cord Con- the receptacle is held rigidly against the box or box cover. nectors. Attachment plugs and cord connectors shall be constructed so that there are no exposed current-carrying parts (C) Receptacles Mounted on Covers. Receptacles except the prongs, blades, or pins. The cover for wire tenmi- mounted to and supported by a cover shall be held rigidly nations shall be a part that is essential for the operation of an against the cover by more than one screw or shall be a attachment plug or connector(dead-front construction). device assembly or box cover listed and identified for se- curing by a single screw. (B) Connection of Attachment Plugs. Attachment plugs shall be installed so that their prongs,blades,or pins are not (D) Position of Receptacle Faces, After installation, re- energized unless inserted into an energized receptacle or ceptacle faces shall be flush with or project from faceplates cord connectors. No receptacle shall be installed so as to of insulating material and shall project a minimum of require the insertion of an energized attachment plug as its 0.4 mm (0.015 in.) from metal faceplates. source of supply. Exception: Listed kits or assemblies encompassing recep- (C) Attachment Plug Ejector Mechanisms. Attachment tacles and nonmetallic faceplates that cover the receptacle plug ejector mechanisms shall not adversely affect engage- face, where the plate cannot be installed on any other re- ment of the blades of the attachment plug with the contacts ceptacle, shall be permitted. of the receptacle, • (E) Receptacles in Countertops and Similar Work Sur- (D) Flanged Surface Inlet.A flanged surface inlet shall be faces in Dwelling Units.Receptacles shall not be installed in installed such that the prongs, blades, or pins are not ener- a face-up position in countertops or similar work surfaces. gized unless an energized cord connector is inserted into it. (F) Exposed Terminals. Receptacles shall be enclosed so 406.7 Noninterchangeability. Receptacles, cord connec- that live wiring terminals are not exposed to contact. tors, and attachment plugs shall be constructed such that receptacle or cord connectors do not accept an attachment (G) Voltage Between Adjacent Devices. A receptacle plug with a different voltage or current rating from that for shall not be grouped or ganged in enclosures with other which the device is intended. However, a 20-ampere T-slot receptacles, snap switches, or similar devices, unless they receptacle or cord connector shall be permitted to accept a are arranged so that the voltage between adjacent devices 15-ampere attachment plug of the same voltage rating. does not exceed 300 volts, or unless they are installed in Non--grounding-type receptacles and connectors shall not enclosures equipped with identified, securely installed bar- accept grounding-type attachment plugs. riers between adjacent devices. 406.8 Receptacles in Damp or Wet Locations. 406.5 Receptacle Faceplates (Cover Plates), Receptacle (A) Damp Locations. A receptacle installed outdoors in a faceplates shall be installed so as to completely cover the location protected from the weather or in other damp loca- opening and seat against the mounting surface. tions shall have an enclosure for the receptacle that is weatherproof when the receptacle is covered (attachment (A) Thickness of Metal Faceplates.Metal faceplates shall plug cap not inserted and receptacle covers closed). be of ferrous metal not less than 0.76 mm (0.030 in.) in An installation suitable for wet locations shall also be thickness or of nonferrous metal not less than 1.02 mm considered suitable for damp locations. (0.040 in.) in thickness. A receptacle shall be considered to be in a location protected from the weather where located under roofed (B) Grounding. Metal faceplates shall be grounded, open porches, canopies, marquees, and the like, and will not be subjected to a beating rain or water runoff. All 15- (C) Faceplates of Insulating Material, Faceplates of in- and 20-ampere, 125- and 250-volt nonlocking receptacles sulating material shall be noncombustible and not less than shall be a listed weather-resistant type. 2.54 mm (0.10 in.)in thickness but shall be permitted to be less than 2.54 mm (0.10 in.) in thickness if formed or rein- am i The types of receptacles ,and 6 by this requirement forced to provide adequate mechanical strength. are identified as 5-I5, 5-20, 6-15,and 6-20 in ANSI/NEMA WD 6-2002, National Electrical Manufacturers Association Standard for Dimensions of Attachment Plugs and 406.6 Attachment Plugs, Cord Connectors, and Receptacles Flanged Surface Devices. All attachment plugs, cord con- nectors, and flanged surface devices (inlets and outlets) (B) Wet Locations. shall be listed and marked with the manufacturer's name or (1) 15- and 20-Ampere Receptacles in a Wet Location. identification and voltage and ampere ratings. 15- and 20-ampere, 125- and 250-volt receptacles installed 70-260 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 406--RECEPTACLES.CORD CONNECTORS,AND ATTACHMENT PLUGS (CAPS) 406.111 in a wet location shall have an enclosure that is weather- A terminal for connection to the grounding pole shall be proof whether or not the attachment plug cap is inserted, designated by one of the following: All 15- and 20-ampere, 125- and 250-volt nonlocking re- (1) A green-colored hexagonal-headed or-shaped terminal ceptaeles shall be listed Weather-resistant type. screw or nut, not readily removable. FPN: The types of receptacles covered by this requirement (2) A green-colored pressure wire connector body (a wire are identified as 5-15,5-20,6-15,and 6-20 in ANSI/NEMA barrel). WD 6-2002,National Electrical Manufacturers Association Standard for Dimensions of Attachment Plugs and (3) A similar green-colored connection device, in the case Receptacles.I of adapters. The grounding terminal of a grounding adapter shall be a green-colored rigid ear, lug, or simi- E.xception: 15- and 20-ampere, 125- through 250-volt re- ceptacles installed in a wet location and subject to routine he so designed that it cannot make contact with high-pressure spray washing shall be permitted to have an current-carrying parts of the receptacle, adapter, or at- removed. enclosure that is weatherproof when the attachment plug is tachment plug. The adapter shall be polarized. (4) If the terminal for the equipment grounding conductor (2) Other Receptacles. All other receptacles installed in a is not visible, the conductor entrance hole shall be wet location shall comply with (B)(2)(a) or (B)(2)(b). marked with the word green or ground, the letters G or (a) A receptacle installed in a wet location, where the GR, a grounding symbol, or otherwise identified by a product intended to be plugged into it is not attended while distinctive green color. If the terminal for the equip- in use, shall have an enclosure that is weatherproof with the ment grounding conductor is readily removable, the attachment plug cap inserted or removed. area adjacent to the terminal shall be similarly marked. (b) A receptacle installed in a wet location where the product intended to be plugged into it will be attended FPN: See FPN Figure 406.9(B)(4). while in use (e.g., portable tools) shall have an enclosure O that is weatherproof when the attachment plug is removed. (C) Bathtub and Shower Space. Receptacles shall not be FPN Figure 406.9(B)(4) One Example of a Symbol Used to installed within or directly over a bathtub or shower stall. Identify the Termination Point for an Equipment Grounding Conductor. (D) Protection for Floor Receptacles. Standpipes of floor (C) Grounding Terminal Use. A grounding terminal shall receptacles shall allow floor-cleaning equipment to be op- not be used for purposes other than grounding. erated without damage to receptacles. (E) Flush Mounting with Faceplate. The enclosure for a (D) Grounding-Pole Requirements. Grounding-type at- receptacle installed in an outlet box Hush-mounted in a fin- tachment plugs and mating cord connectors and receptacles iihed surface shall be made weatherproof by means of a shall be designed such that the equipment grounding con- weatherproof faceplate assembly that provides a watertight nection is made before the current-carrying connections. connection between the plate and the finished surface. Grounding-type devices shall be so designed that grounding poles of attachment plugs cannot be brought into contact with 406.9 Grounding-Type Receptacles, Adapters, Cord current-carrying parts of receptacles or cord connectors. Connectors, and Attachment Plugs. (E) Use. Grounding-type attachment plugs shall be used (A) Grounding Poles. Grounding-type receptacles, cord only with a cord having an equipment grounding conductor. connectors, and attachment plugs shall be provided with FPN: See 200,10(B)for identification of grounded conduc- one fixed grounding pole in addition to the circuit poles, for terminals. The grounding contacting pole of grounding-type plug-in ground-fault circuit interrupters shall be permitted to be of 406.10 Connecting Receptacle Grounding Terminal to the movable, self-restoring type on circuits operating at not Box. The connection of the receptacle grounding terminal over 150 volts between any two conductors or any conduc- shall comply with 250.]46. tor and ground. (B) Grounding-Pole identification. Grounding-type re- 406.11 Tamper-Resistant Receptacles in Dwelling ceptacles, adapters, cord connections, and attachment plugs Units. In all areas Specified in 210.52, all 125-volt, 15- shall have a means for connection of an equipment ground- and 20-ampere receptacles shall be listed tamper- ing conductor to the grounding pole. resistant receptacles. 2008 Edition NATIONAL ELECTRICAL CODE 70-261 408.1 ARTICLE 408--SWITCHBOARDS AND PANELBOARDS switchboard or panelboard frame.All sections of a switch- ARTICLE 408 board shall be bonded together using an equipment bonding Switchboards and Panelboards conductor sized in accordance with Table 250.122 or Table 250.66 as appropriate. I. General Exception: Switchboards and panelboards used as service equipment on high-impedance grounded-neutral systems in 408.1 Scope. This article covers the following: accordance with 250.36 shall not be required to he pro- (1) All switchboards, panelboards, and distribution boards vided with a main bonding jumper installed for the control of light and power circuits (2) Battery-charging panels supplied from light or power (D) Terminals. In switchboards and panelboards, load ter- circuits minals for field wiring, including grounded circuit conduc- tor load terminals and connections to the equipment 408.2 Other Articles.Switches,circuit breakers,and over- Founding conductor bus for load equipment grounding current devices used on switchboards, panelboards,and dis- conductors, shall be so located that it is not necessary to tribution boards, and their enclosures shall comply with this reach across or beyond an uninsuiated ungrounded line bus article and also with the requirements of Articles 240, 250, in order to make connections. 312, 314, 404, and other articles that apply. Switchboards and panelboards in hazardous (classified) locations shall (E) Phase Arrangement. The phase arrangement on c 3-phase buses shall be A, B, C from front to back, top to comply with the requirements of Articles 500 through 517. bottom, or left to right, as viewed from the front of the 408.3 Support and Arrangement of Busbars and switchboard or panelboard.The B phase shall be that phase Conductors. having the higher voltage to ground on 3-phase, 4-wire, delta-connected systems. Other bulbar arrangements shall (A) Conductors and Busbars on a Switchboard or Pan- be permitted for additions to existing installations and shall elboard. Conductors and busbars on a switchboard or pan- be marked, elboard shall comply with 408.3(A)(1), (A)(2), and (A)(3) as applicable. Exception: Equipment within the same single section or multisection switchboard or panelboard as the meter on (1) Location. Conductors and busbars shall be located so 3-phase, 4-wire, delta-connected systems shall be permitted as to be free from physical damage and shall be held firmly to have the same phase configuration as the metering in place. equipment. (2) Service Switchboards. Barriers shalt be placed in all FPN: See 110.15 for requirements on marking the busbar service switchboards such that no uninsuiated, ungrounded or phase conductor having the higher voltage to ground service bulbar or service terminal is exposed to inadvertent where supplied from a 4-wire, delta-connected system. contact by persons or maintenance equipment while servic- ing load terminations. (F) Fiigh-Leg Identification. A switchboard or panelboard containing a 4-wire,delta-connected system where the mid- (3) Same Vertical Section. Other than the required inter- point of one phase winding is grounded shall be legibly and connections and control wiring, only those conductors that permanently field marked as follows: are intended for termination in a vertical section of a "Caution Phase Has _;.,_.,_ Volts to Ground" switchboard shall be located in that section. Exception: Conductors shall be permitted to travel hori- (G) Minimum Wire-Bending Space. The minimum wire- bending space at terminals and minimum gutter Space pro- such through vertical sections of switchboards where vided in panelboards and switchboards shall be as required such conductvrs are isolated from busbars by a barrier. in 312.6. (B) Overheating and Inductive Effects.The arrangement of busbars and conductors shall be such as to avoid over- 408.4 Circuit Directory or Circuit Identification. Every heating due to inductive effects. circuit and circuit modification shall be legibly identified as to its clear, evident, and specific purpose or use.The identifi- (C) Used as Service Equipment. Each switchboard or cation shall include sufficient detail to allow each circuit to be panelboard, if used as service equipment, shall be provided distinguished from all others. Spare positions that contain un- with a main bonding jumper sized in accordance with used overcurrent devices or Switches shall be described ac- 250.28(D) or the equivalent placed within the panelboard cor<lingly.The identification shall be included in a circuit di- or one of the sections of the switchboard for connecting the rectory that is located on the face or inside of the panel door in grounded service conductor on its supply side to the the case of a panelboard, and located at each switch on a 70-262 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 408—SWITCHBOARDS AND PANELBOARDS 408.36 switchboard. No circuit shall be described in a manner that retardant, and shall be rated not less than the voltage ap- depends on transient conditions of occupancy. plied to it and not less than the voltage applied to other 4085 Clearance for Conductor Entering Bus Enclo- conductors or busbars with which it may come in contact. sures. Where conduits or other raceways enter a switch- 408.20 Location of Switchboards. Switchboards that board, floor-standing panelboard, or similar enclosure at the have any exposed live parts shall be located in permanently bottom, sufficient space shall be provided to permit instal- dry locations and then only where under competent super- lation of conductors in the enclosure. The wiring space vision and accessible only to qualified persons. Switch- shall not be less than shown in Table 408.5 where the con- boards shall be located such that the probability of damage duit or raceways enter or leave the enclosure below the from equipment or processes is reduced to a minimum. busbars, their supports, or other obstructions. The conduit or raceways, including their end fittings, shall not rise more 408.22 Grounding of Instruments, Relays, Meters, and than 75 mm (3 in.) above the bottom of the enclosure. Instrument Transformers on Switchboards. Instruments, relays, meters, and instrument transformers located on Table Enclosures Clearance for Conductors Entering Bus switchboards shall be grounded as specified in 250.170 Enclosures $T p through 250.178. Minimum Spacing Between Bottom of Enclosure and Busbars,Their III. Panelboards Supports, or Other Obstructions 408.30 General. All panelboards shall have a rating not Conductor mm in. less than the minimum feeder capacity required for the load Insulated busbars, their 200 g calculated in accordance with Parts II, III, IV, or V of Ar- supports, or other tiele 220 as applicable. obstructions Noninsulated busbars 250 t0 FPN: See 110.22 for additional requirements. 408.7 Unused Openings. Unused openings for circuit • 408.36 Overcurrent Protection. In addition to the re- breakers and switches shall be closed using identified clo- quirement of 408.30, a panelboard Shall be protected by an sures, or other approved means that provide protection sub- overcurrent protective device baving a rating not greater stantially equivalent to the wall of the enclosure. than that of the panelboard.This overcurrent protective de- vice shall be located within or at any point on the supply side of the panelboard. lI. Switchboards Exception No. 1: Individual protection ,shall not be re- 408.16 Switchboards in Damp or Wet Locations. quired for a panelboard used as service equipment with Switchboards in damp or wet locations shall be installed in multiple disconnecting means in accordance with 230.71. accordance with 312.2. In panelboards protected by three or more main circuit breakers or sets of fuses, the circuit breakers or sets of 408.17 Location Relative to Easily Ignitible Material. fuses shall not supply a second bus structure within the Switchboards shall be placed so as to reduce to a minimum ,tame panelboard assembly. the probability of communicating fire to adjacent combus- tible materials. Where installed over a combustible floor, Exception No. 2: .Individual protection shall not be re- suitable protection thereto shall be provided. quired for a panelboard protected on its supply side by two main circuit breakers or two sets of fuses having a com- 408.18 Clearances. bined rating not greater than that of the panelboard. A panelboard constructed or wired under this exception shall (A) From Ceiling. For other than a totally enclosed not contain more than 42 overcurrent devices. For the pur- switchboard, a space not less than 900 mm (3 ft) shall be poses of determining the maximum of 42 overcurrent de- provided between the top of the switchboard and any com- vices, a 2-pole or a 3-pole circuit breaker shall be consid- bustible ceiling, unless a noncombustible shield is provided ered as two or three overcurrent devices, respectively. between the switchboard and the ceiling. Exception No. 3: For existing panelboards, individual pro- (B) Around Switchboards. Clearances around switch- tection shall not be required for a panelboard used as ser- boards shall comply with the provisions of 110.26. vice equipment for an individual residential occupancy. 408.19 Conductor Insulation. An insulated conductor (A) ,Snap Switches Rated at 30 Amperes or Less. Panel- used within a switchboard shall be listed, shall be flame boards equipped with snap switches rated at 30 amperes 2008 Edition NATIONAL ELECTRICAL CODE 70-263 408.37 ARTICLE 408--SWITCHBOARDS AND PANELBOARDS or less shall have overcurrent protection of 200 amperes Exception: Where an isolated equipment grounding con- or less. ductor is provided as permitted by 250.146(D), the insu- lated equipment grounding conductor that is run with the (B) Supplied Through a Transformer. Where a panel- circuit conductors shall be permitted to pass through the board is supplied through a transformer, the overcurrent panelboard without being connected to the panelboard's protection required by 408.36 shall be located on the sec- equipment grounding terminal bar ondary side of the transformer. Equipment grounding conductors shall not be con- Exception: A panelboard supplied by the secondary side of nected to a terminal bar provided for grounded conductors a transformer shall be considered as protected by the over- or neutral conductors unless the bar is identified for the current protection provided on the primary side of the purpose and is located where interconnection between transformer where that protection is in accordance with equipment grounding conductors and grounded circuit con- 240.21(C)(1). ductors is permitted or required by Article 250. (C) Della Breakers. A 3-phase disconnect or overcurrent 408.41 Grounded Conductor Terminations. Each device shall not be connected to the bus of any panelboard grounded conductor shall terminate within the panelboard that has less than 3-phase buses. Delta breakers shall not be in an individual terminal that is not also used for another installed in panelboards. conductor. (D) Back-Fed Devices. Plug-in-type overcurrent protec- Exception: Grounded conductors of circuits with parallel tion devices or plug-in type main lug assemblies that are conductors shall be permitted to terminate in a single ter- backfed and used to terminate field-installed ungrounded urinal if the terminal is identified for connection of more supply conductors shall be secured in place by an addi- than one conductor tional fastener that requires other than a pull to release the device from the mounting means on the panel. IV. Construction Specifications 408.37 Panelboards in Damp or Wet Locations. Panel- 405.50 Panels. The panels of switchboards shall be made boards in damp or wet locations shall be installed to com- of moisture-resistant, noncombustible material. ply with 312.2. 408.51. Busbars. Insulated or bare busbars shall be rigidly 408.38 Enclosure. Panelboards shall be mounted in cabi- mounted. nets, cutout boxes, or enclosures designed for the purpose and shall be dead-front. 408.52 Protection of Instrument Circuits. Instruments, Exception: Panelboards other than of the dead front, ex- pilot lights, potential transformers, and other switchboard ternally operable type shall be permitted where accessible devices with potential coils shall be supplied by a circuit only to qualified persons. that is protected by standard overcurrent devices rated 15 amperes or less. 408.39 Relative Arrangement of Switches and Fuses. In Exception No. 1: Overcurrent devices rated more than 15 panelboards, fuses of any type shall be installed on the load amperes shall be permitted where the interruption of the side of any switches, circuit could create a hazard. Short-circuit protection shall Exception: Fuses installed as part of service equipment in he provided. accordance with the provisions of 23094 shall be permitted Exception No. 2: For ratings of 2 amperes or less, special on the line side of the service switch. types of enclosed fuses shall be permitted. 408.40 Grounding of Panelboards. Panelboard cabinets 408.53 Component Parts. Switches, fuses, and fusehold- and panelboard frames, if of metal, shall be in physical ers used on panelboards shall comply with the applicable contact with each other and shall be connected to an equip- requirements of Articles 240 and 404. ment grounding conductor. Where the panelboard is used with nonmetallic raceway or cable or where separate equip- 408.54 Maximum Number of Overcurrent Devices. A went grounding conductors are provided, a terminal bar for panelboard shall be provided with physical means to pre- the equipment grounding conductors shall be secured inside vent the installation of more overcurrent devices than that the cabinet.The terminal bar shall be bonded to the cabinet number for which the panelboard was designed, rated, and and panelboard frame, if of metal; otherwise it shall be lusted. connected to the equipment grounding conductor that is run For the purposes of thiS Section,a 2-pole circuit breaker or with the conductors feeding the panelboard. fusible switch Shall be considered two overcurrent devices; a 70--.264 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 409—INDUSTRIAL CONTROL PANELS 409,2 3-pole circuit breaker or fusible Switch shall be considered Table 408.56 Minimum Spacings Between Bare Metal Parts three overcurrent devices. Opposite 408.55 Wire-Bending Space in Panelboards. The enclo- Polarity sure for a panelboard shall have the top and bottom wire- Where Opposite space sized in accordance with Table 312.6(B)for the Mounted on Polarity bending�p the Same Where Held Live Parts largest conductor entering or leaving the enclosure. Side wire- Surface Free in Air to Ground* bending space shall be in accordance with Table 312.6(A)for the largest conductor to be terminated in that space. Voltage mm in, mm in. mm in. Exception No. 1: Either the top or bottom wire-bending Not over 125 I9.1 -1/4 12.7 iA 12.7 '/2 space shall be permitted to be sized in accordance with volts, nominal Table 312.6(A)for a panelboard rated 225 amperes or less Not over 250 31.8 1'/-0 19.1 1/a 12.7 1/2 and designed to contain not over 42 overcurrent devices. volts, For the purposes of this exception, a. 2-pole or a 3-pole nominal circuit breaker shall be considered as two or three overcur- Not over 600 50.8 2 25.4 t 25.4 1 rent devices, respectively. volts, nominal Exception No. 2: Either the top or bottom wire-bending space for any panelboard shall be permitted to be sized in For spacing between live parts and doors of cabinets, see accordance with Table 312.6(A) where at least one side 312.11(A)(1), (2), and(3). wire-bending space is sized in accordance with Table 312.6(B)for the largest conductor to be terminated in any side wire-bending space. Exception No. 3: The top and bottom wire-bending space ARTICLE 409 shall be permitted to be sized in accordance with Table Industrial Control Panels 312.6(A) spacings if the panelboard is designed and con- structed for wiring using only one single 90 degree bend I. General for each conductor, including the grounded circuit conduc- tor, and the wiring diagram shows and specifies the method 409.1 ,Scope. This article covers industrial control panels of wiring that shall be used. intended for general use and operating at 600 volts or less. Exception No. 4: Either the top or the bottom wire-bending FPN: UL 508A is a safety standard for industrial control space, but not both, shall be permitted to be sized in accor- panels• dance with Table 312.6(A) where there are no conductors terminated in that space. 409,2 Definitions. Control Circuit. The circuit of a control apparatus or sys- 408.56 Minimum Spacings. The distance between bare tem that carries the electric signals directing the perfor- metal parts, busbars, and so forth shall not be less than maned of the controller but does not carry the main power specified in Table 408.56. current. Where close proximity does not cause excessive heat- ing, parts of the same polarity at switches, enclosed fuses, Industrial Control Panel. An assembly of two or more and so forth shall be permitted to be placed as close to- components consisting of one of the following: gether as convenience in handling will allow. (1) Power circuit components only, such as motor control- lers, overload relays, fused disconnect switches, and Exception: The distance shall be permitted to be less than circuit breakers that specified in Table 408.56 at circuit breakers and (2) Control circuit components only, such as pushbuttons, switches and in listed components installed in switchboards pilot lights, Selector Switches, timers, switches, control and panelboards. relays 408.58 Panelboard Marking. Panelbaards shall be dura- (3) A combination of power and control circuit bly marked by the manufacturer with the voltage and the components current rating and the number of phases for which they are These components, with associated wiring and termi- designed and with the manufacturer's name or trademark in nals, are mounted on or contained within an enclosure or such a manner so as to be visible after installation,without mounted on a subpaneI. The industrial control panel does disturbing,the interior parts or wiring. not include the controlled equipment. 2008 Edition NATIONAL ELECTRICAL CODE 70-,265 409.3 ARTICLE 409—INDUSTRIAL CONTROL PANELS 409.3 Other Articles. In addition to the requirements of (B) Location. This protection shall be provided for each Article 409, industrial control panels that contain branch incoming Supply circuit by either of the following: circuits for specific loads or components, or are for control (1) An overcurrent protective device located ahead of the of specific types of equipment addressed in other articles of industrial control panel. this Code, shall be constructed and installed in accordance (2) A single main overcurrent protective device located with the applicable requirements from the specific articles within the industrial control panel. Where overcurrent in Table 409.3. protection is provided as part of the industrial control Table 409.3 Other Articles panel, the supply conductors shall be considered as ei- ther feeders or taps as covered by 240.21. Equipment/Occupancy Article Section (C) Rating.The rating or setting of the overcurrent protec- Branch circuits 210 tive device for the circuit supplying the industrial control Luminaires 410 panel shall not be greater than the sum of the largest rating Motors, motor circuits, and 430 or setting of the branch-circuit short-circuit and ground- controllers fault protective device provided with the industrial control Air-conditioning and 440 panel, plus 125 percent of the full-load current rating of all refrigerating equipment Capacitors 460.8, 460.9 resistance heating loads, plus the sum of the full-load cur- Hazardous (classified) 500, 501, 502, rents of all other motors and apparatus that could be in locations 503. 504. 505 operation at the same time. Commercial garages; aircrafl 511, 513, 514, hangars, motor fuel 515, 516, and Exception: Where one or more instantaneous trip circuit dispensing facilities; bulk 517 Part IV breakers or motor short-circuit protectors are used for mo- storage plants; spray for branch-circuit short-circuit and ground fault protection application, dipping, and as permitted by 430.52(C), the procedure .specified above coating processes; and inhalation anesthetizing for determining the maximum rating of the protective de- locations vice for the circuit supplying the industrial control panel Cranes and hoists 610 shall apphy with the following provision: For the purpose of Electrically driven or 675 the calculation, each instantaneous trip circuit breaker or controlled irrigation machines motor short-circuit protector shall be assumed to have a Flevators, dumbwaiters, 620 rating not exceeding the maximum percentage of motor escalators, moving walks, full-load current permitted by Table 430.52 for the type of wheelchair lifts, and control panel supply circuit protective device employed. stairway chair lifts Industrial machinery 670 Where no branch-circuit short-circuit and ground-fault Resistors and reactors 470 protective device is provided with the industrial control Transformers 450 panel for motor or combination of motor and non-motor Class I, Class 2, and Class 3 725 loads, the rating or setting of the overcurrent protective remote-control, signaling, and power-limited circuits device shall be based on 430.52 and 430.53, as applicable. 409.30 Disconnecting Means. Disconnecting means that II. installation supply motor loads shall comply with Part IX of Article 430, 409.20 Conductor—Minimum Size and Ampacity.The size of the industrial control panel supply conductor Shall 409.60 Grounding. Multisection industrial control panels have an ampacity not less than 125 percent of the full-load shall be bonded together with an equipment grounding con- current rating of all resistance heating loads plus 125 per- ductor or an equivalent equipment grounding bus sized in cent of the full-load current rating of the highest rated mo- accordance with Table 250.122. Equipment grounding con- tor plus the sum of the full-load current ratings of all other ductors shall be connected to this equipment grounding bus connected motors and apparatus based on their duty cycle or to an equipment grounding termination point provided in that may be in operation at the same time. a single-section industrial control panel. 409.21 Overcurrent Protection. III. Construction Specifications (A) General. Industrial control panels shall be provided 409.100 Enclosures.Table 110.20 shall be used as the ba- with overcurrent protection in accordance with Parts 1, 11, sis for selecting industrial control panel enclosures for and IX of Article 240. use in specific locations other than hazardous (classified) 70-266 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 410—LUMINAIRES,LAMPHOLDERS,AND LAMPS 410.2 locations. The enclosures are not intended to protect 409.110 Marking. An industrial control panel shall be against conditions such as condensation, icing, corro- marked with the following information that is plainly vis- sion, or contamination that may occur within the enclo- ible after installation: sure or enter via the conduit or unsealed openings. (1) Manufacturer's name, trademark, or other descriptive marking by which the organization responsible for the 409.102 Busbars and Conductors. Industrial control pan- product can be identified. els utilizing busbars shall comply with 409.102(A) and (B). (2) Supply voltage, number of phases, frequency, and full- (A) Support and Arrangement. Busbars shall be pro- load current for each incoming supply circuit tected from physical damage and be held firmly in place. (3) Short-circuit current rating of the industrial control panel based on one of the following: (B) Phase Arrangement. The phase arrangement on a. Short-circuit current rating of a listed and labeled 3-phase horizontal common power and vertical buses shall assembly be A, B,C from front to back,top to bottom,or left to right, b. Short-circuit current rating established utilizing an as viewed from the front of the industrial control panel.The approved method B phase shall be that phase having the higher voltage to FPN: UL SO$A, Supplement SB, is an example of an ap- ground on 3-phase, 4-wire, delta-connected systems. Other proved method. busbar arrangements shall be permitted for additions to ex- isting installations and shall be marked. Exception to (3): Short-circuit current rating markings are not required for industrial control panels containing only 409.104 Wiring Space in Industrial Control Panels. control circuit components. (4) If the industrial control panel is intended as service (A) General. Industrial control panel enclosures shall not equipment, it shall be marked to identify it as being be used as junction boxes, auxiliary gutters,or raceways for suitable for use as service equipment. conductors feeding through or tapping off to other switches (5) Electrical wiring diagram or the identification number or overcurrent devices, unless adequate space for this pur- of a separate electrical wiring diagram or a designation pose is provided. The conductors shall not fill the wiring referenced in a separate wiring diagram. space at any cross section to more than 40 percent of the cross-sectional area of the space, and the conductors, (6) An enclosure type number shall be marked on the in- splices, and taps shall not fill the wiring space at any cross dustrial control panel enclosure, section to more than 75 percent of the cross-sectional area of that space. (B) Wire Bending Space. Wire bending space within in- ARTICLE 410 dustrial control panels for field wiring terminals shall be in Luminaires, Lampholders, and Lamps accordance with the requirements in 430.10(B). 409.106 Spacings. Spacings between live bare metal parts 1. General in feeder circuits shall not be IeSs than specified in Table 410.1 Scope.This article covers luminaires,portable lumi- 430.97. naires,lampholders,pendants, incandescent filament lamps, Exception: Spacings shall be permitted to be less than arc lamps, electric-discharge lamps, decorative lighting those specified in Table 430.97 at circuit breakers and products, lighting accessories for temporary seasonal and switches and in listed components installed in industrial holiday use,portable flexible lighting products, and the wir- control panels ing and equipment forming part of such products and light- ing installations. 409.108 Service Equipment. Where used as service 410.2 Definitions. equipment, each industrial control panel shall be of the type that is suitable for use as service equipment. Closet Storage Space. The volume bounded by the sides Where a grounded conductor is provided, the industrial and back closet walls and planes extending from the closet control panel shall be provided with a main bonding floor vertically to a height of 1.8 in (6 ft) or to the highest jumper,sized in accordance with 250.28(D), for connecting clothes-hanging rod and parallel to the walls at a horizontal the grounded conductor, on its supply side, to the industrial distance of 600 mm (24 in.) from the sides and back of the control panel equipment ground bus or equipment ground closet walls, respectively, and continuing vertically to the terminal. closet ceiling parallel to the waits at a horizontal distance of 2008 Edition NATIONAL ELECTRICAL CODE 70-267 410.5 ARTICLE 410—LUMINAIRES,LAMPHOLDERS,AND LAMPS 300 mm(12 in.} cannot enter or accumulate in wiring compartments, lamp- or shelf width 300 mm(12 in.) or shelf width holders, or other electrical parts.All luminaires installed in wet locations shall be marked, "Suitable for Wet Loca- tions." Ali luminaires installed in damp locations shall be �. marked "Suitable for Wet Locations" or "Suitable for i Damp Locations." 300 mm 300 mm (12 in.) (B) Corrosive Locations. Luminaires installed in corro- 1.8 m(6 ft) (12 in.) I or she or 600 Mrn I width live locations shall be of a type suitable for such locations. rod height (24 in.) I (C) In Ducts or Hoods. Luminaires shall be permitted to (2q nm be installed in commercial cooking hoods where all of the I following conditions are met: I (1) The luminaire shall be identified for use within com- mercial cooking hoods and installed such that the tem- perature limits of the materials used are not exceeded, (2) The luminaire shall be constructed so that all exhaust vapors, grease, oil, or cooking vapors are excluded from the lamp and wiring compartment. Diffusers shall Figure 410.2 Closet Storage Space. be resistant to thermal shock. 300 mm (12 in.) or the width of the shelf, whichever is (3) Parts of the luminaire exposed within the hood shall be greater; for a closet that permits access to both sides of a corrosion resistant or protected against corrosion, and hanging rod, this space includes the volume below the the surface shall be smooth so as not to collect deposits highest rod extending 300 mm (12 in.) on either side of the and to facilitate cleaning. rod on a plane horizontal to the Floor extending the entire (4) Wiring methods and materials supplying the lumi- length of the rod. See Figure 410.2. naire(s) shall not be exposed within the cooking hood. Lighting Track. A manufactured assembly designed to FPN: See 110.11 for conductors and equipment exposed to support and energize luminaires that are capable of being deteriorating agents. readily repositioned on the track, its length can be altered by the addition or subtraction of sections of track. (D) Bathtub and Shower Areas. No parts of cord- • connected luminaires, chain-, cable-, or cord-suspended lu- 410.5 Live Parts. Luminaires, portable luminaires, lam- minaires, lighting track, pendants, or ceiling-suspended pholders, and lamps shall have no live parts normally ex- (paddle) fans shall be located within a zone measured posed to contact. Exposed accessible terminals in lam- 900 mm (3 ft) horizontally and 2.5 m (8 ft) vertically from pholders and switches shall not be installed in metal the top of the bathtub rim or shower stall threshold. This luminaire canopies or in open bases of portable table or zone is all encompassing and includes the Space directly floor luminaires. over the tub or shower stall. Luminaires located within the Exception: Cleat-Hype lanipholders located at least 2.5 in actual outside dimension of the bathtub or Shower to a (8 ft) above the floor shall he permitted to have exposed height of 2.5 m(8 ft) vertically from the top of the bathtub terminals. rim or shower threshold shall be marked for damp loca- tions, or marked for wet locations where subject to shower 410.6 Listing Required. All luminaires and lampholders spray, shall be listed. (E) Luminaires in indoor Sports, Mixed-Use, and All- 410.8 Inspection. Luminaires shall be installed such that Purpose Facilities.Luminaires subject to physical damage, the connections between the luminaire conductors and the using a mercury vapor or metal halide lamp, installed in circuit conductors can be inspected without requiring the playing and spectator seating areas of indoor sports, mixed- disconnection of any part of the wiring unless the lumi- use, or all-purpose facilities shall be of the type that pro- naires are connected by attachment plugs and receptacles. tects the lamp with a glass or plastic lens. Such luminaires shall be permitted to have an additional guard. II. Luminaire Locations 410.11 Luminaires Near Combustible Material. Lumi- 410.10 Luminaires in Specific Locations. naires shall be constructed, installed, or equipped with (A) Wet and Damp Locations. Luminaires installed in shades or guards so that combustible material is not sub- wet or damp locations shall be installed such that water jected to temperatures in excess of 90°C (194°F). 70-268 NATIONAL ELL TRiCAL CODE 2008 Edition ARTICLE 410--LUMINAIRES,LAMPHOLDERS,AND LAMPS 410.30 41032 Luminaires over Combustible Material. Lamp- naire conductors and their connecting devices can be prop- holders installed over highly combustible material shall be erly installed. of the unswitched type. Unless an individual switch is pro- vided for each luminaire, lampholders shall be located at 410.21: Temperature Limit of Conductors in Outlet least 2.5 m (8 ft) above the floor or shall be located or Boxes.Luminaires shall be of such construction or installed guarded so that the lamps cannot be readily removed or so that the conductors in outlet boxes shall not be subjected damaged. to temperatures greater than that for which the conductors are rated. 410.14 Luminaires in Show Windows. Chain-supported Branch-circuit wiring, other than 2-wire or multiwire luminaires used in a show window shall be permitted to be branch circuits supplying power to luminaires connected externally wired. No other externally wired luminaires shall together,shall not be passed through an outlet box that is an be used. integral part of a luminaire unless the luminaire is identified 410.16 Luminaires in Clothes Closets. for through-wiring. (A) Luminaire Types Permitted. Listed Iuminaires of the FPN: See 410.65 for wiring supplying power to fixtures following types shall be permitted to be installed in a connected together. closet: 410.22 Outlet Boxes to Be Covered. In a completed in- (1) A surface-mounted or recessed incandescent luminaire stallation, each outlet box shall be provided with a cover with a completely enclosed lamp unless covered by means of a luminaire canopy, lamp- (2) A surface-mounted or recessed fluorescent luminaire holder, receptacle, or similar device. (3) Surface-mounted fluorescent or LED iumindires identi- fied as suitable for installation within the storage area 410.23 Covering of Combustible Material at Outlet Boxes. Any combustible wall or ceiling finish exposed be- (B) Luminaire Types Not Permitted. Incandescent lumi- Lween the edge of a luminaire canopy or pan and an outlet naires with open or partially enclosed lamps and pendant box shall be covered with noncombustible material. luminaires or lampholders shall not be permitted. (C) Location.The minimum clearance between luminaires 410.24 Connection of Electric-Discharge Luminaire. installed in clothes closets and the nearest point of a storage (p) Independent of the Outlet Box.Electric-discharge lu- space shall be as follows: minaires supported independently of the outlet box shall be (1) 300 mm (12 in.) for surface-mounted incandescent or connected to the branch circuit through metal raceway, LED luminaires with a completely enclosed light nonmetallic raceway, Type MC cable,Type AC cable,Type source installed on the wall above the door or on the MI cable,nonmetallic sheathed cable, or by flexible cord as ceiling permitted in 410.62(B) or 410.62(Q. (2) 150 mm (6 in.) for surface-mounted fluorescent lumi- (B) Access to Boxes. Electric-discharge luminaires surface naires installed on the wall above the door or on the ceiling mounted over concealed outlet, pull, or junction boxes and designed not to be supported solely by the outlet box shall (3) 150 mm (6 in.) for recessed incandescent or LED lu- be provided with suitable openings in the back of the lumi- minaires with a completely enclosed light source in- stalled in the wall or the ceiling naire to provide access to the wiring in the box. (4) 150 mm. (6 in.) for recessed fluorescent luminaires in- stalled in the wall or the ceiling IV. Luminaire Supports (5) Surface-mounted fluorescent or LED luminaires shall 410.30 Supports. be permitted to be installed within the storage space where identified for this use. (A) General Luminaires and lampholders shall be se- curely supported. A luminaire that weighs more than 3 kg 410.18 Space for Cove Lighting. Coves shall have ad- (6 lb) or exceeds 400 mm (16 in.) in any dimension shall equate space and shall be located so that lamps and equip- not be supported by the screw shell of a lampholder. ment can be properly installed and maintained. B Metal or Nonmetallic Poles( ) Supporting Luminaires. Metal or nonmetallic poles shall be permitted to be used to III. Provisions at Luminaire Outlet Boxes, Canopies, support luminaires and as a raceway to enclose supply con- and Pans ductors, provided the following conditions are met: 410.20 Space for Conductors. Canopies and outlet boxes (1) A pole shall have a handhole not less than 50 mm taken together shall provide adequate space so that lumi- x 100 mm(2 in. x 4 in.)with a cover suitable for use in 2008 Edition NATIONAL ELECTRICAL CODE 70-269 410.36 ARTICLE 410 LUMINAIRES,LAMPHOLDERS,AND LAMPS wet locations to provide access to the supply termina- made of steel, malleable iron, or other material suitable for tions within the pole or pole base. the application. Exception No. 1: No handhole shall be required in a pole (D) Insulating,Points. Insulating joints that are not designed 2.5 in (8 ft) or less in height abovegrade where the supply to be mounted with screws or bolts shall have an exterior wiring method continues without splice or pull point, and metal casing, insulated from both screw connections. where the interior of the pale and any splices are accessible by removing the luminaire. (E) Raceway Fittings. Raceway fittings used to support a Exception No. 2: No handhole shall be required in a pole luminaire(s) shall be capable of supporting the weight of 6.0 m (20 ft) or less in height abovegrade that is provided the complete fixture assembly and lamp(s). with a hinged base. (ff) Busways. Luminaires shall be permitted to be con- (2) Where raceway risers or cable is not installed within netted to busways in accordance with 368.17(C). the pole, a threaded fitting or nipple shall be brazed, welded, or attached to the pole opposite the handhole (G) Trees. Outdoor luminaires and associated equipment for the supply connection. shall be permitted to be supported by trees. (3) A metal pole shall be provided with an equipment FPN No, l: See 225.26 for restrictions for support of over- grounding terminal as follows: head conductors. a. A pole with a handhole shall have the equipment FPN No. 2: See 300.5(D) for protection of conductors. grounding terminal accessible from the handhole. b. A pole with a hinged base shall have the equipment grounding terminal accessible within the base. V. Grounding Exception to (3): No grounding terminal shall be required 410.40 General. Luminaires and lighting equipment shall in a pole 2.5 m(8 ft)or less in height abovegrade where the be grounded as required in Article 250 and Part V of this supply wiring method continues without splice or pull, and article. where the interior of the pole and any splices are accessible by removing the luminaire. 410.42 Exposed Luminaire. (4) A metal pole with a hinged base shall have the hinged (A) Exposed Conductive Parts.Exposed metal parts shall base and pole bonded together. be connected to an equipment grounding conductor or in- (5) Metal raceways or other equipment grounding conduc- sulated from the equipment grounding conductor and other tors shall be bonded to the metal pole with an equip- conducting surfaces or be inaccessible to unqualified per- ment grounding conductor recognized by 250.118 and sonnel. Lamp tie wires, mounting screws, clips, and deco- sized in accordance with 250.122. rative bands on glass spaced at least 38 mm (1112 in.) from (6) Conductors in vertical poles used as raceway shall be lamp terminals shall not be required to be grounded. supported as provided in 300.19. (B) Made of Insulating Material. Luminaires directly 410.36 Means of Support. wired or attached to outlets supplied by a wiring method that does not provide a ready means for grounding attachment to (A) Outlet Boxes. Outlet boxes or fittings installed as re- an equipment grounding conductor shall be made of insulating quired by 314.23 and complying with the provisions of material and shall have no exposed conductive parts. 314.27(A) and 314.27(B) shall he permitted to support lu- Exception No. 1: Replacement luminaires shall be permit- minaires. ted to connect an equipment grounding conductor from the (B) Suspended Ceilings. Framing members of suspended outlet in compliance with 250.130(C). The luminaire shall ceiling systems used to support luminaires shall be securely then comply with 410.42(A). fastened to each other and shall be securely attached to the Exception No. 2: Where no equipment grounding conduc- building structure at appropriate intervals. Luminaires shall for exists at the outlet, replacement luminaires that are be securely fastened to the ceiling framing member by me- GFCI protected shall not be required to be connected to an chanical means such as bolts, screws, or rivets. Listed clips equipment grounding conductor identified for use with the type of ceiling framing mem- bers) and luminaire(s) shall also be permitted. 410.44 Equipment Grounding Conductor Attachment. Luminaires with exposed metal parts shall be provided with (C) Luminaire Studs. Luminaire studs that are not a part a means for connecting an equipment grounding conductor of outlet boxes, hickeys, tripods, and crowfeet shall be for such luminaires. 70-270 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 410—LUMINA[RES, LAMPHOLDERS,AND LAMPS 410.59 410.46 Methods of Grounding. Luminaires and equip- (C) Luminaire Stems. Splices and taps shall not be lo- ment shall be mechanically connected to an equipment cated within luminaire arms or stems. grounding conductor as specified in 250.118 and sized in accordance with 250.122. (D) Splices and Taps. No unnecessary splices or taps shall be made within or on a luminaire. VI. Wiring of Luminaires FPN: For approved means of making connections, see 110.14. 410.48 Luminaire Wiring — General. Wiring on or within Iuminaires shall be neatly arranged and shall not be (E) Stranding. Stranded conductors shall be used for wir- exposed to physical damage. Excess wiring shall be ing on luminaire chains and on other movable or flexible avoided. Conductors shall be arranged so that they are not pis, subjected to temperatures above those for which they are rated. (F) Tension. Conductors shall be arranged so that the weight of the luminaire or movable parts does not put ten- 410.50 Polarization of Luminaires. Luminaires shall be sion on the conductors. wired so that the screw shells of lampholders are connected to the same luminaire or circuit conductor or terminal. The 410.59 Cord-Connected Showcases. Individual show- grounded conductor, where connected to a screw shell lamp- cases, other than fixed, shall be permitted to be connected holder, shall be connected to the screw shell. by flexible cord to permanently installed receptacles, and groups of not more than six such showcases shall be per- 410.52 Conductor Insulation. Luminaires shall be wired mitted to be coupled together by flexible cord and separable with conductors having insulation suitable for the environ- locking-type connectors with one of the group connected mental conditions, current, voltage, and temperature to by flexible cord to a permanently installed receptacle. which the conductors will be subjected. The installation shall comply with 410.59(A) through(E), FPN: For ampacity of fixture wire, maximum operating temperature, voltage limitations, minimum wire size, and (A) Cord Requirements. Flexible cord shall be of the so forth, see Article 402. hard-service type, having conductors not smaller than the branch-circuit conductors,having ampacity at least equal to 410.54 Pendant Conductors for Incandescent Filament the branch-circuit overcurrent device, and having an equip- Lamps. ment grounding conductor. (A) Support. Pendant lampholders with permanently at- FPN: See Table 250.122 for size of equipment grounding tached leads, where used for other than festoon wiring, conductor. shall be hung from separate stranded rubber-covered con- ductors that are soldered directly to the circuit conductors (B) Receptacles, Connectors, and Attachment Plugs. but supported independently thereof. Receptacles, connectors, and attachment plugs shall be of a listed grounding type rated 15 or 20 amperes. (B) Size. Unless part of listed decorative lighting assem- blies,pendant conductors shall not be smaller than 14 AWG (C) Support. Flexible cords shall be secured to the under- for mogul-base or medium-base screw shell lampholders or sides of showcases such that all of the following conditions smaller than 18 AWG for intermediate or candelabra-base are ensured: lampholders. (1) The wiring is not exposed to physical damage. (C) Twisted or Cabled. Pendant conductors longer than (2) The separation between cases is not in excess of 50 mm 900 mm (3 ft) shall be twisted together where not cabled in (2 in.), or more than 300 mm (12 in.) between the first a listed assembly. case and the supply receptacle. (3) The free lead at the end of a group of showcases has a 410.56 Protection of Conductors and Insulation. female fitting not extending beyond the case. (A) Properly Secured. Conductors shall be secured in a (D) No Other Equipment. Equipment other than show- manner that does not tend to cut or abrade the insulation. cases shall not be electrically connected to showcases. (B) Protection Through Metal. Conductor insulation (E) Secondary Circuit(s). Where showcases are cord- shall be protected from abrasion where it passes through connected, the secondary circuit(s) of each electric- metal. discharge lighting ballast shall be limited to one showcase. 2008 Edition NATIONAL ELECTRICAL CODE 70-271 410.62 ARTICLE 410—LUMINAIRES,LAMPHOLDERS,AND LAMPS 410.62 Cord-Connected Lampholders and Luminaires, 410.64 Luminaires as Raceways. Luminaires shall not be used as a raceway for circuit conductors unless listed and (A) Lampholders. Where a metal lampholder is attached marked For use as a raceway. to a flexible cord, the inlet shall be equipped with an insu- lating bushing that, if threaded, is not smaller than metric 410.65 Wiring Supplying Luminaires Connected To- designator 12 (trade size -3/s) pipe size. The cord hole shall gether. Luminaires designed for end-to-end connection to be of a size appropriate for the cord, and all burrs and fins form a continuous assembly, or luminaires connected to- shall be removed in order to provide a smooth bearing gether by recognized wiring methods, shall be permitted to surface for the cord. contain the conductors of a 2-wire branch circuit, or one Bushing having holes 7 mm (V32 in.) in diameter shall multiwire branch circuit, supplying the connected lumi- be permitted for use with plain pendant cord and holes 1] mm ("/:z in.) in diameter with reinforced cord. noires and need not be listed as a raceway. One additional 2-wire branch circuit separately supplying one or more of (B) Adjustable Luminaires. Luminaires that require ad- the connected luminaires shall also be permitted. justing or aiming after installation shall not be required to ppN: See Article 100 for the definition of Multiwire be equipped with an attachment plug or cord connector, Branch Cirruit. provided the exposed cord is of the hard-usage or extra- hard-usage type and is not longer than that required for 410.68 Feeder and Branch-Circuit Conductors and maximum adjustment. The cord shall not be subject to Ballasts.Feeder and branch-circuit conductors within 75 mm strain or physical damage. (3 in.) of a ballast shall have an insulation temperature rating not lower than 90°C (194°F) unless supplying a luminaire (C) Electric-Discharge Luminaires. marked as suitable for a different insulation temperature. (1) Cord-Connected Installation. A luminaire or a listed assembly shall be permitted to be cord connected if the VII. Construction of Luminaires Following conditions apply: (1) The luminaire is located directly below the outlet or 410.70 Combustible Shades and Enclosures. Adequate busway. airspace shall be provided between lamps and shades or (2) The flexible cord meets all the following: other enclosures of combustible material. a. Is visible for its entire length outside the luminaire b. Is not subject to strain or physical damage 410.74 Luminaire Rating. c. Is terminated in a grounding-type attachment plug (A) Marking. All luminaires shall be marked with the cap or busway plug, or is a part of a listed assembly maximum lamp wattage or electrical rating, manufacturer's incorporating a manufactured wiring system con- name, trademark, or other suitable means of identification. nector in accordance with 604.6(C), or has a lumi- A luminaire requiring supply wire rated higher than 60°C naire assembly with a strain relief and canopy hav- (140°F) shall be marked with the minimum supply wire ing a maximum 152 mm (6 in.) long section of temperature rating on the luminaire and shipping carton or raceway for attachment to an outlet boat above a equivalent, suspended ceiling (2) Provided with Mogul-Base, Screw Shell Lamphold- (B) Electrical Rating. The electrical rating shall include ers. Electric-discharge luminaires provided with mogul- the voltage and frequency and shall indicate the current base, screw shell lampholders shall be permitted to be con- rating of the unit, including the ballast, transformer, or au- netted to branch circuits of 50 amperes or less by cords totransformer. complying with 240.5. Receptacles and attachment plugs 410.76 Design and Material. Luminaires shall be con- shall be permitted to be of a lower ampere rating than the branch circuit but not less than 125 percent of the luminaire strutted of metal, wood, or other material suitable for the full-load current, application and shall be designed and assembled so as to secure requisite mechanical strength and rigidity. Wiring (3) Equipped with Flanged Surface Inlet. Electric- compartments, including their entrances, shall be designed discharge luminaires equipped with a flanged surface inlet and constructed to permit conductors to be drawn in and shall be permitted to be supplied by cord pendants withdrawn without physical damage. equipped with cord connectors. Inlets and connectors shall be permitted to be of a lower ampere rating than the branch 410.77 Nonmetallic Luminaires. When luminaire wiring circuit but not less than 125 percent of the luminaire load compartments are constructed from combustible mate- current. rial, armored or lead-covered conductors with suitable 70-272 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 410—LUMINAIRES, LAMPHOLDERS,AND LAMPS 410.702 fittings shall be used or the wiring compartment shall be (4) Metallic guards shall be grounded by means of an lined with metal. equipment grounding conductor run with circuit con- ductors within the power-supply cord. 410.78 Mechanical Strength. (5) Portable handlamps shall not be required to be (A) Tubing for Arms. Tubing used for arms and stems grounded where supplied through an isolating trans- where provided with cut threads shall not be less than former with an ungrounded secondary of not over 50 L02 mm (0.040 in.) in thickness and, where provided with volts. rolled (pressed) threads, shall not be less than 0.64 mm (0.025 in.) in thickness. Arms and other parts shall be fas_ 410.84 Cord Bushings. A bushing or the equivalent shall tened to prevent turning. be provided where flexible cord enters the base or stem of a portable luminaire. The bushing shall be of insulating ma- (B) Metal Canopies.Metal canopies supporting lamphold- terial unless a jacketed type of cord is used. ers, shades, and so forth exceeding 4 kg (8 lb), or incorpo- rating attachment-plug receptacles, shall not be less than 410.85 Tests. All wiring shall be free from short circuits 0.51 mm (0.020 in.) in thickness. Other canopies shall not and ground faults as defined in 250.2 and shall be tested for be less than 0.41 mm (0.016 in.) if made of steel and not these defects prior to being connected to the circuit. less than 0.51 mm (0.020 in.) if of other metals. 410.86 Live Parts. Exposed live parts within porcelain lu- (C) Canopy Switches. Pull-type canopy switches shall not minaires shall be suitably recessed and located so as to be inserted in the rims of metal canopies that are less than make it improbable that wires come in contact with them. 0.64 mm (0.025 in.) in thickness, unless the rims are rein- There shalt be a spacing of at least 13 mm ('/2 in.)between forced by the turning of a bead or the equivalent. Pull-type live parts and the mounting plane of the luminaire. canopy switches,whether mounted in the rims or elsewhere in sheet metal canopies, shall not be located more than VIII. Installation of Lampholders 90 mm (31/2 in.) from the center of the canopy. Double set p screws, double canopy rings, a screw ring,or equal method 410.90 Screw Shell Type. Lampholders of the screw shell shall be used where the canopy supports a pull-type switch type shall be installed for use as lampholders only. Where or pendant receptacle. supplied by a circuit having a grounded conductor, the The thickness requirements in the preceding paragraph grounded conductor shall be connected to the screw shell. shall apply to measurements made on finished (formed) canopies. 410.93 Double-Pole Switched Lampholders. Where sup- plied by the ungrounded conductors of a circuit,the switch- 410.79 Wiring Space. Bodies of luminaires, including ing device of lampholders of the switched type shall simul- portable luminaires, shall provide ample space for splices taneously disconnect both conductors of the circuit. and taps and for the installation of devices, if any. Splice compartments shall be of nonabsorbent, noncombustible 410.96 Lampholders in Wet or Damp Locations. Lamp- material. holders installed in wet or damp locations shall be of the weatherproof type. 410.82 Portable Luminaires. (A) General. Portable luminaires shall be wired with flex- IX. Construction of Lampholders ibte cord recognized by 400.4 and an attachment plug of 410.100 Insulation.The outer metal shell and the cap shall the polarized or grounding type. Where used with Edison- be lined with insulating material that prevents the shell and base lampholders, the grounded conductor shall be identi- cap from becoming a part of the circuit.The lining shall not fied and attached to the screw shell and the identified blade extend beyond the metal shell more than 3 mm (%a in.) but of the attachment plug. shall prevent any current-carrying part of the lamp base (B) Portable Handlamps. In addition to the provisions from being exposed when a Iamp is in the lampholding of 410.82(A), portable handlamps shall comply with the device. following: 410.102 Switched Lampholders. Switched lampholders (1) Metal shell, paper-lined lampholders shall not be used. shall be of such construction that the switching mechanism (2) Handlamps shaft be equipped with a handle of molded interrupts the electrical connection to the center contact. composition or other insulating material. The switching mechanism shall also be permitted to inter- (3) Handlamps shall be equipped with a substantial guard rupt the electrical connection to the screw shell if the con- attached to the lampholder or handle. nection to the center contact is simultaneously interrupted. 2008 Edition NATIONAL ELECTRICAL CODE 70-273 410.103 ARTICLE 410—LUMINAIRES,LAMPHOLDERS.AND LAMPS X. Lamps and Auxiliary Equipment materials.The points of support and the trim finishing off the opening in the ceiling or wall surface shall be per- 410.703 Bases, Incandescent Lamps. An incandescent mitted to be in contact with combustible materials. lamp for general use on lighting branch circuits shall not be equipped with a medium base if rated over 300 watts, or (2) Type IC. A recessed luminaire that is identified for with a mogul base if rated over 1500 watts. Special bases or contact with insulation, Type IC,shall be permitted to be in other devices shall be used for over 1500 watts. contact with combustible materials at recessed parts, points of support, and portions, passing through or finishing off the 410.104 Electric-Discharge Lamp Auxiliary Equipment. opening in the building structure. (A) Enclosures. Auxiliary equipment for electric- (B) Installation. Thermal insulation shall not be installed discharge lamps shall be enclosed in noncombustible cases above a recessed luminaire or within 75 mm (3 in.) of the and treated as sources of heat. recessed luminaire's enclosure, wiring compartment, or ballast unless it is identified for contact with insulation, (B) Switching. Where supplied by the ungrounded con- Type IC. ductors of a circuit,the switching device of auxiliary equip- ment shall simultaneously disconnect all conductors. 410.117 Wiring. (A) General. Conductors that have insulation suitable for X1. Special Provisions for Flush and Recessed the temperature encountered shall be used. Luminaires (B) Circuit Conductors. Branch-circuit conductors that 410.110 General. Luminaires installed in recessed cavities have an insulation suitable for the temperature encountered in walls or ceilings shall comply with 410.115 through shall be permitted to terminate in the luminaire. 410.122. (C) Tap Conductors.Tap conductors of a type suitable for the temperature encountered shall be permitted to run from 410.115 Temperature. the luminaire terminal connection to an outlet box placed at (A) Combustible Material. Luminaires shall be installed least 300 mm (1 ft) from the luminaire. Such tap conduc- so that adjacent combustible material will not be subjected tors shall be in suitable raceway or Type AC or MC cable to temperatures in excess of 90°C (194°F). of at least 450 mm (18 in.) but not more than 1.8 m(6 ft) in length. (B) Fire-Resistant Construction.Where a luminaire is re- cessed in fire-resistant material in a building of fire- resistant construction, a temperature higher than 90°C XII. Construction of Flush and Recessed Luminaires (194°F) but not higher than 150°C (302°F) shall be consid- 410.11$ Temperature. Luminaires shall be constructed ered acceptable if the luminaire is plainly marked for that such that adjacent combustible material is not subject to service. temperatures in excess of 90°C (194°F). (C) Recessed Incandescent Luminaires. Incandescent lu 410.120 Lamp Wattage Marking. Incandescent lamp lu- minaires shall have thermal protection and shalt be identi- minaires shall be marked to indicate the maximum allow- fied as thermally protected. able wattage of lamps. The markings shall be permanently Exception No. 1: Thermal protection shall not be required installed, in letters at least 6 mm (1/4 in.) high, and shall be in a recessed luminaire identified for use and installed in located where visible during relamping. poured concrete. 410.121 Solder Prohibited. No solder shall be used in the Exception No. 2: Thermal protection shall not be required construction of a luminaire box. in a recessed luminaire whose design, construction, and thermal performance characteristics are equivalent to a 410.1,22 Lampholders. Lampholders of the screw shell therincrlly protected luminaire and are identified as inkier- type shall be of porcelain or other suitable insulating mate- entl��protected. rials. Where used, cements shall be of the high-heat type. 410.116 Clearance and Installation. XIII. Special Provisions for Electric-Discharge (A) Clearance. Lighting Systems of 1000 Volts or Less (1) Non-Type IC. A recessed luminaire that is not identi- 410.130 General. tied for contact with insulation shall have all recessed parts (A) Open-Circuit Voltage of 1000 Volts or Less. Equip- spaced not less than 13 mm (I/2 in.) from combustible ment for use with electric-discharge lighting systems and 70-274 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 410—LUMINAIRES,LAMPHOLDERS,AND LAMPS 410.135 designed for an open-circuit voltage of 1000 volts or less physical means that only allows the use of a lamp that is shall be of a type identified for such service. Type O. (B) Considered as Energized. The terminals of an FPN: See ANSI Standard 076389, American National electric-discharge lamp shall be considered as energized Standard for Electric Lamps—High Intensity Discharge: where any lamp terminal is connected to a circuit of over Methods of Measuring Characteristics. 300 volts. (G) Disconnecting :Means. (C) Transformers of the Oil-Filled Type. Transformers (1) General. In indoor locations other than dwellings and of the oil-filled type shall not be used. associated accessory structures, fluorescent luminaires that utilize double-ended lamps and contain ballast(s) that can (D) Additional Requirements. In addition to complying be serviced in place shall have a disconnecting means ei- with the general requirements for luminaires, such equip- ther internal or external to each luminaire. The line side ment shall comply with Part XIII of this article. terminals of the disconnecting means shall be guarded. (E) Thermal Protection — Fluorescent Luminaires. Exception No. 1: A disconnecting means shall not be re- quired for luminaires installed in hazardous (classified) (1) Integral Thermal Protection.The ballast of a fluvres- location(s). cent luminaire installed indoors shall have integral thermal protection. Replacement ballasts shall also have thermal Exception No. 2: A disconnecting means shall not be re- protection integral with the ballast. quired for emergency illumination required in 700.16. Exception No. 3: For cord-and-plug-connected luminaires, (2) Simple Reactance Ballasts.A simple reactance ballast an accessible separable connector or an accessible plug in a fluorescent luminaire with straight tubular lamps shall and accessible shall be not be required to be thermally protected, receptacle permitted to serve as the discon- necting means. (3) Exit Fixtures. A ballast in a fluorescent exit luminaire Exception No. 4: A disconnecting means shall not be re- shall not have thermal protection. quired in industrial establishments with restricted public access where conditions of maintenance and supervision (4) Egress Luminaires. A ballast in a fluorescent lumi- ensure that only qualified persons service the installation naire that is used for egress lighting and energized only e en by during a failure of the normal supply shall not have thermal written procedures. protection. Exception No. S: Where more than one luminaire is in- stalled and supplied by other than a multiwire branch cir- (F) High-intensity Discharge Luminaires. cuit, a disconnecting means shall not be required far every (1) Recessed. Recessed high-intensity luminaires designed luminaire when the design of the installation includes dis- to be installed in wall or ceiling cavities shall have thermal connecting means, such that the illuminated space cannot in total darkness. protection and be identified as thermally protected. be left (2) Inherently Protected. Thermal protection shall not be (2) Multiwire Branch Circuits. When connected to mul- required in a recessed high-intensity luminaire whose de- tiwire branch circuits, the disconnecting means shall simulz sign, construction, and thermal performance characteristics taneously break all the supply conductors to the ballast, are equivalent to a thermally protected luminaire and are including the grounded conductor. identified as inherently protected. (3) Location.The disconnecting means shall be located so (3) Installed in Poured Concrete.Thermal protection shall as to be accessible to qualified persons before servicing or not be required in a recessed high-intensity discharge lumi- maintaining the ballast. Where the disconnecting means is external to the luminaire, it shall be a single device and naire identified for use and installed in poured concrete. shall he attached in the luminaire or the luminaire shall be (4) Recessed Remote Ballasts. A recessed remote ballast located within sight of the disconnecting means. for a high-intensity discharge luminaire shall have thermal protection that is integral with the ballast and shall be iden- 410.134 Direct-Current Equipment.Luminaires installed tified as thermally protected. on do circuits shall be equipped with auxiliary equipment and resistors designed for do operation. The luminaires (5) Metal Halide Lamp Containment. Luminaires that shall be marked for do operation. use a metal halide lamp other than a thick-glass parabolic reflector lamp (PAR) shall be provided with a containment 410.135 Open-Circuit Voltage Exceeding 300 Volts. barrier that encloses the lamp, or shall be provided with a Equipment having an open-circuit voltage exceeding 300 2008 Edition NATIONAL ELECTRICAL CODE 70-275 410.136 ARTICLE 410—LUMINAIRES,LAMPHOLDERS,AND LAMPS volts shall not be installed in dwelling occupancies unless 410.139 Switches. Snap switches shall comply with such equipment is designed so that there will be no exposed 404.14. live parts when lamps are being inserted, are in place, or are being removed. XIV. Special Provisions for Electric-Discharge 410.136 Luminaire Mounting. Lighting Systems of More Than 1000 Volts (A) Exposed Ballasts. Luminaires that have exposed bal- 410.140 General. lasts or transformers shall be installed such that such bal- (A) Listing. Electric-discharge lighting systems with an lasts or transformers will not be in contact with combus- open-circuit voltage exceeding 1000 volts shall be listed tible material. and installed in conformance with that listing. (B) Combustible Low-Density Cellulose Fiberboard. (B) Dwelling Occupancies. Equipment that has an open- Where a surface-mounted luminaire containing a ballast is circuit voltage exceeding I000 volts shall not be installed to be installed on combustible low-density cellulose fiber- in or on dwelling occupancies. board, it shall be marked for this condition or shall be spaced not less than 38 mm(1'/2 in.)from the surface of the (C) Live Parts.The terminal of an electric-discharge lamp fiberboard. Where such luminaires are partially or wholly shall be considered as a live part, recessed, the provisions of 410.110 through 410.122 shall apply. (D) Additional Requirements. In addition to complying with the general requirements for luminaires, such equip- FPN: Combustible low-density cellulose fiberboard in- ment shall comply with Part XIV of this article. cludes sheets, panels, and tiles that have a density of 320 kg/m' (20 lb/f[3) or less and that are formed of bonded FPN: For signs and outline lighting, see Article 600. plant fiber material but does not include solid or laminated wood or fiberboard that has a density in excess of 320 410.141 Control. kg/m' (20 lb/ft') or is a material that has been integrally treated with fire-retarding chemicals to the degree that the (A) Disconnection. Luminaires or lamp installation shall flame spread in any plane of the material will not exceed be controlled either singly or in groups by an externally 25,determined in accordance with tests for surface burning operable switch or circuit breaker that opens all un- characteristics of building materials. See ANSI/ASTM E84-1997,Test Method for Surface Burning Characteristics grounded primary conductors. of Building Materials. (B) Within Sight or Locked Type. The switch or circuit 410.137 Equipment Not Integral with Luminaire. breaker shall be located within sight from the luminaires or lamps, or it shall be permitted elsewhere if it is provided (A) Metal Cabinets. Auxiliary equipment, including reac- with a means for locking in the open position. The provi- tors,capacitors,resistors, and similar equipment, where not sions for locking or adding a Iock to the disconneefiing installed as part of a luminaire assembly, shall be enclosed means must remain in Place at the switch or circuit breaker in accessible, permanently installed metal cabinets, whether the lock is install ed or not. Portable means for (B) Separate Mounting. Separately mounted ballasts that adding a lock to the switch or circuit breaker shall riot be are intended for direct connection to a wiring system shall permitted, not be required to be separately enclosed. 410.142 Lamp Terminals and Lampholders. Parts that (C) Wired Luminaire Sections. Wired luminaire sections must be removed for lamp replacement shall be hinged or are paired, with a ballast(s) supplying a lamp or lamps in held captive. Lamps or lampholders shall be designed so both. For interconnection between paired units, it shall be that there are no exposed live parts when lamps are being permissible to use metric designator 12 (trade size;/s) flex- inserted or removed. ible metal conduit in lengths not exceeding 7.5 m (25 ft),in conformance with Article 348. Luminaire wire operating at 410.143 Transformers. line voltage, supplying only the ballast(s) of one of the (A) Type. Transformers shall be enclosed, identified for paired luminaires shall be permitted in the same raceway as the use, and listed. the lamp supply wires of the paired luminaires. (B) Voltage. The secondary circuit voltage shall not ex- 410.138 A utotrans formers. An autotransformer that is ceed 15,000 volts, nominal, under any load condition. The used to raise the voltage to more than 300 volts, as part of voltage to ground of any output terminals of the second- a ballast for supplying lighting units, shall be supplied only ary circuit shall not exceed 7500 volts under any load by a grounded system. conditions. 70-276 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 410—LUMINAIRES.LAMPHOLDERS,AND LAMPS 410,160 (C) Rating. Transformers shall have a secondary short- (5) In hazardous (classified) locations circuit current rating of not more than 150 mA if the open- (6) Where concealed circuit voltage is over 7500 volts, and not more than 300 mA (7) Where extended through walls or partitions if the open-circuit voltage rating is 7500 volts or less. (8) Less than 1.5 m (5 ft) above the finished floor except (D) Secondary Connections. Secondary circuit outputs where protected from physical damage or track operat- shall not be connected in parallel or in series. ing at less than 30 volts rms open-circuit voltage 410.144 Transformer Locations. (9) Where prohibited by 410.10(D) (A) Accessible. Transformers shall be accessible after in- (D) Support. Fittings identified for use on lighting track stallation. shall be designed specifically for the track on which they are to be installed. They shall be securely fastened to the (B) Secondary Conductors. Transformers shall be in- track, shall maintain polarization and connections to the stalled as near to the lamps as practicable to keep the sec- equipment grounding conductor, and shall be designed to ondary conductors as short as possible. be suspended directly from the track. (C) Adjacent to Combustible Materials. Transformers 410.153 Heavy-Duty Lighting 'Lack. Heavy-duty light- shall be located so that adjacent combustible materials are ing track is lighting track identified for use exceeding 20 not subjected to temperatures in excess of 90°C (194°F). amperes. Each fitting attached to a heavy-duty lighting 410.145 Exposure to Damage. Lamps shall not be located track shall have individual overcurrent protection. where normally exposed to physical damage. 410.154 Fastening. Lighting track shall be securely 410.146 Marking. Each luminaire or each secondary cir- mounted so that each fastening is suitable for supporting cuit of tubing having an open-circuit voltage of over 1000 the maximum weight of luminaires that can be installed. volts shall have a clearly legible marking in letters not less Unless identified for supports at greater intervals, a single than 6 mm (%4 in.) high reading "Caution volts." The section 1.2 m (4 ft) or shorter in length shall have two voltage indicated shall be the rated open-circuit voltage. supports, and, where installed in a continuous row, each individual section of not more than 1.2 m (4 ft) in length 410.147 Switches. Snap switches shall comply with 404.4. shall have one additional support. XV. Lighting Track 410.1:55 Construction Requirements. 410.151 Installation. (A) Construction. The housing for the lighting track sys- (A) Lighting 'Lack. Lighting track shall be permanently tem shall be of substantial construction to maintain rigidity. installed and permanently connected to a branch circuit. The conductors shall be installed within the track housing, Only lighting track fittings shall be installed on lighting Permitting insertion of a luminaire, and designed to prevent track. Lighting track fittings shall not be equipped with tampering and accidental contact with live parts. Compo- general-purpose receptacles. nents of lighting track systems of different voltages shall not be interchangeable. The track conductors shall be a (B) Connected Load. The connected load on lighting minimum 12 AWG or equal and shall be copper. The track track shall not exceed the rating of the track. Lighting track system ends shall be insulated and capped. shall be supplied by a branch circuit having a rating not more than that of the track. (B) Grounding.Lighting track shall be grounded in accor- dance with Article 250, and the track sections shall be se- length The load calculation le in branch circuit,does not limit the curely coupled to maintain continuity of the circuitry, po- length of track on a Single branch circuit, and it does not limit the number of luminaires on a single track. larization, and grounding throughout. (C) Locations Not Permitted. Lighting track shall not be installed in the following locations: XVI. Decorative Lighting and Similar Accessories (l) Where likely to be subjected to physical damage 410.160 Listing of Decorative Lighting.Decorative light- (2) in wet or damp locations ing and similar accessories used for holiday lighting and (3) Where subject to corrosive vapors similar purposes, in accordance with 590.3(B), shall be (4) In storage battery rooms listed. 2008 Edition NATIONAL ELECTRICAL CODE 70-277 411.1 ARTICLE 422—APPLIANCES horizontally from the nearest edge of the water,unless per- ART ICLE 411 mitted,by Article 684. Lighting Systems Operating at 30 Volts or Less 411.5 Secondary Circuits. (A) Grounding. Secondary circuits shall not be grounded. 411.1 Scope.This article covers lighting systems operating at 30 volts or less and their associated components. ($) Isolation. The secondary circuit shall be insulated from the branch circuit by an isolating transformer. 411.2 Definition. (C) Bare Conductors. Exposed bare conductors and Lighting Systems Operating at 30 Volts or Less. A light- current-carrying parts shall be permitted for indoor instal- ing system consisting of an isolating power supply, the low- lations only. Bare conductors shall not be installed less than voltage luminaires,and associated equipment that are all iden- 2.1 m (7 ft) above the finished floor, unless specifically tified for the use.The output circuits of the power supply are listed for a lower installation height. rated for not more than 25 amperes and operate at 30 volts (42.4 volts peak)or less under all load conditions. (D) Insulated Conductors. Exposed insulated secondary 411.3 Listing Required. Lighting systems operating at 30 circuit conductors shall be of the type, and installed as, described in (1), (2), or (3): volts or less shall comply with 411.3(A) or 411.3(B). (1) Class 2 cable supplied by a Class 2 power source and (A) Listed System.Lighting systems operating at 30 volts installed in accordance with Parts I and III of Article or less shall be listed as a complete system.The luminaires, 725. power supply,and luminaire fittings(including the exposed (2) Conductors, cord, or cable of the listed system and bare conductors)of an exposed bare conductor lighting sys- installed not less than 2.1 m (7 ft) above the finished tem shall be listed for the use as part of the same identified floor unless the System is specifically listed for a lower lighting system. installation height. (B) Assembly of Fisted Parts. A lighting system as- (3) Wiring methods described in Chapter 3 sembled from the following listed parts shall be permitted: (1) Low-voltage luminaires 411.6 Branch Circuit. Lighting systems operating at 30 (2) Low-voltage luminaire power supply volts or less shall be supplied from a maximum 20-ampere (3) Class 2 power supply branch circuit. (4) Low-voltage Iuminaire fittings 411.7 Hazardous (Classified) Locations. Where installed (5) Cord (secondary circuit) for which the luminaires and in hazardous (classified) locations, these systems shall con- power supply are listed for use form with Articles 500 through 517 in addition to this article. (6) Cable, conductors in conduit, or other fixed wiring method for the secondary circuit The luminaires, power supply, and luminaire fittings (including the exposed bare conductors)of an exposed bare ARTICLE 422 conductor lighting system shall be listed for use as part of the same identified lighting system. Appliances 411.4 Specific Location Requirements. I. General (A) Walls,Floors,and Ceilings.Conductors concealed or extended through a wall, floor, or ceiling shall be in actor- 422.1 Scope. This article covers electrical appliances used dance with (1) or(2): in any occupancy. (1) Installed using any of the wiring methods specified in 422.3 Other Articles. The requirements of Article 430 Chapter 3 shall apply to the installation of motor-operated appliances, (2) Installed using wiring supplied by a listed Class 2 and the requirements of Article 440 shall apply to the in- power source and installed in accordance with 725.130 stallation of appliances containing a hermetic refrigerant (B) Pools, Spas, Fountains, and Similar Locations. motor-compressor(s),except as specifically amended in this Lighting systems shall be installed not less than 3 m (10 ft) article. 70--278 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 422—APPLIANCES 422.11 422.4 Live Parts. Appliances shall have no live parts nor- (D) Open-Coil or Exposed Sheathed-Coil Types of Sur- mally exposed to contact other than those parts functioning face Heating Elements in Commercial-Type Heating as open-resistance heating elements, such as the heating Appliances. Open-coil or exposed sheathed-coil types of element of a toaster, which are necessarily exposed. surface heating elements in commercial-type heating appli- ances shall be protected by overcurrent protective devices II. Installation rated at not over 50 amperes. 422.10 Branch-Circuit Rating. This section specifies the (E) Single Non—motor-Operated Appliance. If the ratings of branch circuits capable of carrying appliance cur- branch circuit supplies a single non—motor-operated appli- rent without overheating under the conditions specified. ance, the rating of overcurrent protection shalt comply with the following: (A) Individual Circuits. The rating of an individual (1) Not exceed that marked on the appliance. branch circuit shall not be less than the marked rating of the (2) Not exceed 20 amperes if the overcurrent protection appliance or the marked rating of an appliance having com- rating is not marked and the appliance is rated 133 bined loads as provided in 422.62. amperes or less; or The rating of an individual branch circuit for motor- operated appliances not having a marked rating shall be in (3) Not exceed 150 percent of the appliance rated current if the overcurrent protection rating is not marked and the accordance with Part 11 of Article 430. appliance is rated over 13.3 amperes. Where 150 per- The branch-circuit rating for an appliance that is a con- tinuvu5 load, other than amotor-operated appliance, shall cent of the appliance rating does not correspond to a not be less than 125 percent of the marked rating, or not standard overcurrent device ampere rating, the next less than 100 percent of the marked rating if the branch- higher standard rating shall be permitted. circuit device and its assembly are listed for continuous (F) Electric Heating Appliances Employing Resistance- loading at 100 percent of its rating. Type Heating Elements Rated More Than 48 Amperes. Branch circuits and brunch-circuit conductors for household ranges and cooking appliances shall be permit- (1) Electric Heating Appliances. Electric heating appli- ted to be in accordance with Table 220.55 and shall be ances employing resistance-type heating elements rated sized in accordance with 210.19(A)(3). more than 48 amperes, other than household appliances with surface heating elements covered by 422.11(B), and (B) Circuits Supplying Two or More Loads. For branch commercial-type heating appliances covered by 422.11(D), circuits supplying appliance and other loads, the rating shall have the heating elements subdivided. Each subdi- shall be determined in accordance with 210.23. vided load shall not exceed 48 amperes and shall be pro- tected at not more than 60 amperes. 422.11 Overcurrent Protection. Appliances shall be pro- These supplementary overcurrent protective devices tected against overcurrent in accordance with 422.11(A) shall be (1) factory-installed within or on the heater enclo- through (G) and 422.10. sure or provided as a separate assembly by the heater manufacturer; (2) accessible; and (3) suitable for branch- (A) Branch-Circuit Overcurrent Protection. Branch cir- circuit protection. cuits shall be protected in accordance with 240.4. The main conductors supplying these overcurrent pro- If aprotective device rating is marked on an appliance, tective devices shall be considered branch-circuit conduc- the branch-circuit overcurrent device rating shall not ex- tors. ceed the protective device rating marked on the appliance. (2) Commercial Kitchen and Cooking Appliances.Com- (B) Household-Type Appliances with Surface Heating mercial kitchen and cooking appliances using sheathed- Elements. Household-type appliances with surface heating type heating elements not covered in 422.11(D) shall be elements having a maximum demand of more than 60 am- permitted to be subdivided into circuits not exceeding 120 peres calculated in accordance with Table 220.55 shall have amperes and protected at not more than 150 amperes where their power supply subdivided into two or more circuits, one of the following is met: each of which shall be provided with overcurrent protection (1) Elements are integral with and enclosed within a cook- rated at not over 50 amperes. ing surface. (C) Infrared Lamp Commercial and Industrial Heating (2) Elements are completely contained within an enclosure Appliances. Infrared lamp commercial and industrial heat- identified as suitable for this use. ing appliances shall have overcurrent protection not ex- (3) Elements are contained within an ASME-rated and ceeding 50 amperes. stamped vessel. 2008 Edition NATIONAL ELECTRICAL COPE 70-279 422.12 ARTICLE 422—APPLIANCES (3) Water Heaters and Steam Boilers. Water heaters and (C)Accessible nott-current-carrying metal parts Of'the cen- steam boilers employing resistance-type immersion electric tral vacuum outlet assembly shall be connected to an equip- heating elements contained in an ASME-rated and stamped ment grounding conductor. vessel or listed instantaneous water heaters shall be permit- ted to be subdivided into circuits not exceeding 120 am- 422.16 Flexible Cords. peres and protected at not more than 150 amperes. (A) General. Flexible cord shall be permitted (1) for the connection of appliances to facilitate their frequent inter- operated appliances shall be provided with overload protec- (G) Motor-Operated Appliances. Motors of motor- change or to prevent the transmission of noise or vibration or tion in accordance with Part III of Article 430. Hermetic (2)to facilitate the removal or disconnection of appliances that are fastened in place,where the fastening means and mechani- refrigerant motor-compressors in air-conditioning or refrig- cal connections are specifically designed to permit ready re- crating equipment shall be provided with overload protec- moval for maintenance or repair and the appliance is intended tion in accordance with Part VI of Article 440. Where ap- or identified for flexible cord connection. pliance overcurrent protective devices that are separate from the appliance are required, data for selection of these (B) Specific Appliances. devices shall be marked on the appliance. The minimum (1) Electrically Operated Kitchen Waste Disposers. marking shall be that specified in 430.7 and 440.4. Electrically operated kitchen waste disposers shall be per- mitted to be cord-and-plug-connected with a flexible cord 422.12 Central Heating Equipment. Central heating identified as suitable for the purpose in the installation in- equipment other than fixed electric space-heating equip- structions of the appliance manufacturer, where all of the ment shall be supplied by an individual branch circuit. following conditions are met: Exception Nn. 1: Auxiliary equipment, such as a pump, (1) The flexible cord shall be terminated with a grounding- valve, humidifier, or electrostatic air cleaner directly assn- type attachment plug. ciated with the treating equipment, shall be permitted to be connected to the same branch circuit. Exception: A listed kitchen waste disposer distinctly marked to identify it as protected by a system of double Exception No. 2: Permanently connected air-conditioning insulation, or its equivalent, shrill not be required to be equipment shall be permitted to be connected to the .same terminated with a grounding-type attachment plug. branch circuit. (2) The length of the cord shall not be less than 450 mm 422.13 Storage-Type Water Heaters. A fixed storage- (18 in.) and not over 900 mm (36 in.). type water heater that has a capacity of 450 L (120 gal) or (3) Receptacles shall be located to avoid physical damage less shall be considered a continuous load for the purposes to the flexible cord. of sizing branch circuits. (4) The receptacle shall be accessible, FPN: For branch-circuit rating, see 422.10. (2) Built-in Dishwashers and Trash Compactors. Built-in dishwashers and trash compactors shall be permit- 422.14 Infrared Lamp Industrial Heating Appliances. ted to be cord-and-plug-connected with a flexible cord In industrial occupancies, infrared heating appliance lamp- identified as suitable for the purpose in the installation in- holders shall be permitted to be operated in series on cir- structions of the appliance manufacturer where all of the cuits of over 150 volts to ground, provided the voltage following conditions are met: rating of the lampholders is not less than the circuit voltage. (1) The flexible cord shall be terminated with a grounding- Each section, panel, or strip carrying a number of infra- type attachment plug. red lampholders (including the internal wiring of such sec- Exception: A listed dishwasher or trash compactor dis- tion, panel, or strip) shall be considered an appliance. The tinctly marked to identify it as protected by a system of terminal connection block of each such assembly shall be double insulation, or its equivalent, shall not be required to considered an individual outlet. be terminated with a grounding-type attachment plug. 422.15 Central Vacuum Outlet Assemblies. (2) The length of the cord shall be 0.9 m to 1.2 m (3 ft to 4 ft) measured from the face of the attachment plug to (A) Listed central vacuum outlet assemblies shall be per- the plane of the rear of the appliance. mitted to be connected to a branch circuit in accordance (3) Receptacles shall be located to avoid physical damage with 210.23(A). to the flexible cord. (B)The ampacity of the connecting conductors shall not be (4) The receptacle shall be located in the space occupied less than the ampacity of the branch circuit conductors to by the appliance or adjacent thereto. which they are connected. (5) The receptacle shall be accessible. 70-280 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 422—APPLIANCES 422.33 (3) Wall-Mounted Ovens and Counter-Mounted Cook- 422.31 Disconnection of Permanently Connected ing Units.Wall-mounted ovens and counter-mounted cook- Appliances. ing units complete with provisions for mounting and for Horse- making electrical connections shall be permitted to he per- (A) Rated at Not over 300 Volt-Amperes or 'A Horse- manently connected or, only for ease in servicing or for Power. For permanently connected appliances rated at not installation, cord-and-plug-connected. over 300 volt-amperes or '1s hp, the branch-circuit overcur- A separable connector or a plug and receptacle combi- rent device shall be permitted to serve as the disconnecting nation in the supply line to an oven or cooking unit shall be means. approved for the temperature of the space in which it is (g) Appliances Rated over 300 Volt-Amperes or 1/8 located. Horsepower. For permanently connected appliances rated (4) Range Hoods. Range hoods shall be permitted to be over 300 volt-amperes or I/a hp, the branch-circuit switch or cord-and-plug-connected with a flexible cord identified as circuit breaker shall be permitted to serve as the discon- suitable for use on range hoods in the installation instruc- necting means where the switch or circuit breaker is within tions of the appliance manufacturer, where all of the foI- sight from the appliance or is capable of being locked in the lowing conditions are met: open position.The provision for locking or adding a lock to (1) The flexible cord is terminated with a grounding-type the disconnecting means shall be installed on or at the switch or circuit breaker used as the disconnecting means attachment plug. and shall remain in place with or without the lock installed. Exception: A listed range hood distinctly marked to iden- tify it as protected by a system of double insulation, or its FPN: For appliances employing unit switches,see 422.34. equivalent, shall not be required to be terminated with a grounding-type attachment plug. 422.32 Disconnecting Means for Motor-Driven Appli- ance.If a switch or circuit breaker serves as the disconnect- (2) The length of the cord is not less than 450 mm (18 in.) ing means for a permanently connected motor-driven appli- and not over 900 mm (36 in.). ance of more than 1/s hp, it shall be located within sight (3) Receptacles are located to avoid physical damage to the from the motor controller and shall comply with Part IX of flexible cord. Article 430. (4) The receptacle is accessible. Exception: If a motor-driven appliance of more than !/a hp (5) The receptacle is supplied by an individual branch is provided with a unit switch that complies with 422.34(A), circuit. (B), (C), or(D), the switch or circuit breaker serving as the other disconnecting means shall be permitted to be out of 422.17 Protection of Combustible Material. Each elec- sight from the motor controller trically heated appliance that is intended by size, weight, and service to be located in a fixed position shall be placed 422.33 Disconnection of Cord-and-Plug-Connected Ap- so as to provide ample protection between the appliance pliances. and adjacent combustible material. (A) Separable Connector or an Attachment Plug and 422.18 Support of Ceiling-Suspended (Paddle) Fans. Receptacle. For cord-and-plug-connected appliances, an Ceiling-suspended (paddle) fans shall be supported inde- accessible separable connector or an accessible plug and pendently of an outlet box or by listed outlet box or outlet receptacle shall he permitted to serve as the disconnecting box systems identified for the use and installed in accor- means. Where the separable connector or plug and recep- dance with 314.27(D). tacle are not accessible, cord-and-plug-connected appli- ances shall be provided with disconnecting means in accor- 422.20 Other Installation Methods. Appliances employ- dance with 422.31. ing methods of installation other than covered by this article (B) Connection at the Rear Base of a Range. For cord- shall be permitted to be used only by special permission. and-plug-connected household electric ranges, an attach- ment plug and receptacle connection at the rear base of a III. Disconnecting Means range, if it is accessible from the front by removal of a drawer, shall be considered as meeting the intent of 422.30 General. A means shall be provided to disconnect 422.33(A). each appliance from all ungrounded conductors in accor- dance with the following sections of Part III. If an appli- (C) Rating. The rating of a receptacle or of a separable ance is supplied by more than one source,the disconnecting connector shall not be less than the rating of any appliance means shall be grouped and identified. connected thereto. 2008 Edidon NATIONAL ELECTRICAL CODE 74-281 422.34 ARTICLE 422—APPLIANCES Exception: Demand factors authorized elsewhere in this against electrocution when immersed while in the "on" or Code shall be permitted to be applied to the rating of a "of" position. receptacle or of a separable connector. 422.42 Signals for Heated Appliances. In other than 422.34 Unit Switch(es) as Disconnecting Means. A unit dwelling-type occupancies, each electrically heated appli- switch(es) with a marked-off position that is a part of an ante or group of appliances intended to be applied to com- appliance and disconnects all ungrounded conductors shall bustible material shall be provided with a signal or an in- be permitted as the disconnecting means required by this tegral temperature-limiting device. article where other means for disconnection are provided in occupancies specified in 422.34(A) through (D). 422,43 Flexible Cords. (A) Multifamily Dwellings. In multifamily dwellings, the (A) Heater Cords. All cord-and-plug-connected smooth- other disconnecting means shall be within the dwelling ing irons and electrically heated appliances that are rated at unit, or on the same floor as the dwelling unit in which the more than 50 watts and produce temperatures in excess of appliance is installed, and shall be permitted to control 121°C (250°F) on surfaces with which the cord is likely to lamps and other appliances. be in contact shall be provided with one of the types of approved heater cords listed in Table 400.4. (B) 'Iwo-Family Dwellings. In two-family dwellings, the other disconnecting means shall be permitted either inside (B) Other Heating Appliances. All other cord-and-plug- or outside of the dwelling unit in which the appliance is connected electrically heated appliances shall be connected installed. In this case, an individual switch or circuit with one of the approved types of cord listed in Table breaker for the dwelling unit shall be permitted and shall 400.4, selected in accordance with the usage specified in also be permitted to control tamps and other appliances. that table. (C) One-Family Dwellings. In one-family dwellings, the 422.44 Cord-and-Plug-Connected Immersion Heaters. service disconnecting means shall be permitted to be the Electric heaters of the cord-and-plug-connected immersion other disconnecting means. type shall be constructed and installed so that current- carrying parts are effectively insulated from electrical con- (D) Other Occupancies. In other occupancies, the branch- tact with the substance in which they are immersed. circuit switch or circuit breaker, where readily accessible for servicing of the appliance, shall be permitted as the 422.45 Stands for Cord-and-Plug-Connected Appli- other disconnecting means. antes. Each smoothing iron and other cord-and-plug- connected electrically heated appliance intended to be ap- 422.35 Switch and Circuit Breaker to Be Indicating. plied to combustible material shall be equipped with an Switches and circuit breakers used as disconnecting means approved stand, which shall be permitted to be a separate shall be of the indicating type. piece of equipment or a part of the appliance. 422.46 Flatirons.Electrically heated smoothing irons shall IV. Construction be equipped with an identified temperature-limiting means. 422.40 Polarity in Cord-and-Plug-Connected Appli- ances. If the appliance is provided with a manually oper- 422.47 Water Heater Controls. All storage or ated, line-connected, single-pole switch for appliance on— instantaneous-type water heaters shall be equipped with a off operation, an Edison-base lampholder, or a 15- or 20- temperature-limiting means in addition to its control ther- ampere receptacle, the attachment plug shall be of the mostat to disconnect all ungrounded conductors. Such polarized or grounding type. means shall comply with both of the following: A 2-wire, nonpolarized attachment plug shall be permit- (1) Installed to sense maximum water temperature. ted to be used on a listed double-insulated shaver. (2) Be either a trip-free, manually reset type or a type hav- ing a replacement element. Such water heaters shall be 410. For polarity of Edison-base lampholders, see marked to require the installation of a temperature and 410.82(A). pressure relief valve. 422.41 Cord-and-Plug-Connected Appliances Subject Exception No. 1: Storage water heaters that are identified to Immersion. Cord-and-plug-connected portable, free- as being suitable for use with a supply water temperature standing hydromassage units and hand-held hair dryers of 82°C (180Y) or above and a capacity of 60 kW or shall be constructed to provide protection for personnel above. 70-282 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 422--APPLIANCES 422.62 Exception No. 2: Instantaneous-type water heaters that are V. Marking identified as being suitable for such use, with a capacity of 422.60 Nameplate. 4 L(1 gal) or less. (A) Nameplate Marking. Each electrical appliance shall FPN: See ANSI Z21.22-1999/CSA 4.4-M99, Relief Valves be provided with a nameplate giving the identifying name for Not Water Suppl} 5ysrems. and the rating in volts and amperes, or in volts and watts. If 422.48 Infrared Lamp Industrial Heating Appliances. the appliance is to be used on a specific frequency or fre- quencies, it shall be so marked. (A) 300 Watts or Less. Infrared heating lamps rated at 300 Where motor overload protection external to the appli- watts or less shall be permitted with lampholders of the ance is required, the appliance shall be so marked. medium-base, unswitched porcelain type or other types FPN: See 422.11 for overcurrent protection requirements, identified as suitable for use with infrared heating lamps rated 300 watts or less. (B) To Be Visible. Marking shall be located so as to be visible or easily accessible after installation. (B) Over 300 Watts. Screw shell lampholders shall not be used with infrared lamps rated over 300 watts, unless the 422.61 Marking of Heating Elements. All heating ele- lampholders are identified as being suitable for use with ments that are rated over one ampere, replaceable in the infrared heating lamps rated over 300 watts. field, and a part of an appliance shall be legibly marked with the ratings in volts and amperes, or in volts and watts, 422.49 High-Pressure Spray Washers. All single-phase or with the manufacturer's part number. cord-and-plug-connected high-pressure spray washing ma- chines rated at 250 volts or less shall be provided with 422.62 Appliances Consisting of Motors and Other factory-installed ground-fault circuit-interrupter protection Loads. for personnel. The ground-fault circuit interrupter shall be (A) Nameplate Horsepower Markings. Where a motor- an integral part of the attachment plug or shall be located in operated appliance nameplate includes a horsepower rating, the supply cord within 300 mm (12 in.) of the attachment that rating shall not be less than the horsepower rating on the plug• motor nameplate.Where an appliance consists of multiple mo- tors, or one or more motors and other loads, the nameplate 422.50 Cord-and-Plug-Connected Pipe Heating Assem- value shall not be less than the equivalent horsepower of the blies. Cord-and-plug-connected pipe heating assemblies in- combined loads,calculated in accordance with 430.110(C)(1). tended to prevent freezing of piping shall be listed. (B) Additional Nameplate Markings. Appliances, other 422.51 Cord-and-Plug-Connected Vending Machines. than those factory-equipped with cords and attachment Cord-and-plug-connected vending machines manufactured plugs and with nameplates in compliance with 422.60,shall or re-manufactured on or after January 1, 2005, shall in- be marked in accordance with 422.62(B)(1) or (13)(2). clude a ground-fault circuit interrupter as an integral part of (1) Marking. In addition to the marking required in the attachment plug or be located within 300 mm(12 in.)of 422,60, the marking on an appliance consisting of a motor the attachment plug. Older vending machines manufactured with other load(s) or motors with or without other load(s) or remanufactured prior to January 1, 2005, shall be con- shall specify the minimum supply circuit conductor ampac- nected to a GFCI-protected outlet. For the purpose of this ity and the maximum rating of the circuit overcurrent pro- section, the term vending machine means any self-service tective device. This requirement shall not apply to an ap- device that dispenses products or merchandise without the pliance with a nameplate in compliance with 422.60 where necessity of replenishing the device between each vending both the minimum supply circuit conductor ampacity and operation and is designed to require insertion of a coin, maximum rating of the circuit overcurrent protective device paper currency, token, card, key, or receipt of payment by are not more than 15 amperes. other means. (2) Alternate Marking Method. An alternative marking FPN: For further information, see ANSI/UL 541-2005, method shall be permitted to specify the rating of the larg- Standani for Refrigerated Vending Machines, or ANSVUL est motor in volts and amperes, and the additional load(s)in 751-2005,Standard for Vending Machines. volts and amperes, or volts and watts in addition to the marking required in 422.60. The ampere rating of a motor 422.52 Electric Drinking Fountains. Electric drinking 1/g horsepower or less or a nonmotor load 1 ampere or less fountains Shall be protected with ground-fault circuit- shall be permitted to be omitted unless such loads consti- interrupter protection. tute the principal load. 2008 Edition NATIONAL ELECTRICAL CODE 70-283 424.1 ARTICLE 424—FIXED ELECTRIC SPACE-HEATING EQUIPMLNT insulation shall be clearly and permanently marked. This ARTICLE 424 marking shall be plainly visible after installation and shall Fixed Electric Space-Heating Equipment be permitted to be adjacent to the field connection box. 424.12 Locations. I. General (A) Exposed to Physical Damage. Where subject to 424.1 Scope. This article covers fixed electric equipment physical damage, fixed electric space-heating equipment used for space heating. For the purpose of this article, heat- shall be protected in an approved manner. ing equipment shall include heating cable, unit heaters, boilers, central systems, or other approved fixed electric (B) Damp or Wet Locations. Heaters and related equip- space-heating equipment. This article shall not apply to ment installed in damp or wet locations shall be listed for process heating and room air conditioning. such locations and shall be constructed and installed so that water or other liquids cannot enter or accumulate in or on 424.2 Other Articles. Fixed electric space-heating equip- wired sections, electrical components, or ductwork. ment incorporating a hermetic refrigerant motor-compressor FPN No. 1: See 110.11 for equipment exposed to deterio- shall also comply with Article 440. rating agents. 424.3 Branch Circuits. FPN No. 2: See 680.27(C) for pool deck areas. (A) Branch-Circuit Requirements. Individual branch cir- 424.13 Spacing from Combustible Materials. Fixed cuits shall be permitted to supply any size fixed electric electric space-heating equipment shall be installed to pro- space-heating equipment. vide the required spacing between the equipment and adja- Branch circuits supplying two or more outlets for fixed cent combustible material, unless it is listed to be installed electric space-heating equipment shall be rated 15, 20, 25, in direct contact with combustible material. or 30 amperes. In nondweIling occupancies, fixed infrared heating equipment shall be permitted to be supplied from III. Control and Protection of Fixed Electric branch circuits rated not over 50 amperes. Space-Heating Equipment (B) Branch-Circuit Sizing. Fixed electric space-heating 424.19 Disconnecting Means. Means shall be provided to equipment shall be considered continuous load. simultaneously disconnect the heater, motor controller(s), and supplementary overcurrent protective device(s) of all 424.6 Listed Equipment.Electric baseboard heaters, heat- fixed electric space-heating equipment from all ungrounded ing cables, duct heaters, and radiant heating systems shall conductors. Where heating equipment is supplied by more be listed and labeled. than one source, the disconnecting means shall be grouped and marked. The disconnecting means specified in II. Installation 424.19(A)and(B)shall have an ampere rating not less than 125 percept of the total load of the motors and the heaters. 424.9 General. All fixed electric space-heating equipment The provision for locking or adding a lock to the discon- shall be installed in an approved manner, necting means shall be installed on or at the switch or Permanently installed electric baseboard heaters equipped circuit breaker used as the disconnecting means and shall with factory-installed receptacle outlets, or outlets provided as remain in place with or without the lock installed. a separate listed assembly, shall be permitted in lieu of a re- ceptacle outlet(s) that is required by 210.50(B). Such recep- (A) Heating Equipment with Supplementary Overcur- tacle outlets shall not be connected to the heater circuits. rent Protection.The disconnecting means for fixed electric space-heating equipment with supplementary overcurrent FPN: Listed baseboard heaters include instructions that protection shall be within sight from the supplementary may not permit their installation below receptacle outlets. overcurrent protective device(s), on the supply side of these 424.10 Special Permission. Fixed electric space-heating devices, if fuses, and, in addition, shall comply with either 424.19(A)(1) or (A)(2). equipment and systems installed by methods other than covered by this article shall be permitted only by special (1) Heater Containing No Motor Rated over '/4 Horse- permission. power. The above disconnecting means or unit switches complying with 424.19(C)shall be permitted to serve as the 424.11 Supply Conductors. Fixed electric space-heating required disconnecting means for both the motor control- equipment requiring supply conductors with over 60°C ler(s) and heater under either of the following conditions: 70-254 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 424—FIXED ELECTRIC SPACE-HEATING EQUIPMENT 424,22 (1) The disconnecting means provided is also within sight or outside of the dwelling unit in which the fixed heater is from the motor controller(s) and the heater. installed. In this case, an individual switch or circuit (2) The disconnecting means provided is capable of being breaker for the dwelling unit shall be permitted and shall locked in the open position. also be permitted to control lamps and appliances. (2) Heater Containing a Motor(s) Rated over 1/s Horse- (3) One-Family Dwellings. In one-family dwellings, the power. The above disconnecting means shall be permitted service disconnecting means shall be permitted to be the to serve as the required disconnecting means for both the other disconnecting means. motor controller(s) and heater by one of the following (4) Other Occupancies. In other occupancies, the branch- means: circuit switch or circuit breaker, where readily accessible (1) Where the disconnecting means is also in sight from for servicing of the fixed heater, shall be permitted as the the motor controller(s) and the heater. other disconnecting means. (2) Where the disconnecting means is not within sight from the heater, a separate disconnecting means shall 424.20 Thermostatically Controlled Switching Devices. be installed, or the disconnecting means shall be ca- pable of being lacked in the open position, or unit (A) Serving as Both Controllers and Disconnecting switches complying with 424.19(C) shall be permitted. Means. Thermostatically controlled switching devices and combination thermostats and manually controlled switches (3) Where the disconnecting means is not within sight shall be permitted to serve as both controllers and discon- from the motor controller location, a disconnecting necting means, provided they meet all of the following means complying with 430.102 shall be provided. conditions: (4) Where the motor is not in sight from the motor control- (]) Provided with a marked "off' position ler location, 430.102($) shall apply, (2) Directly open all ungrounded conductors when manu- (B) Heating Equipment Without Supplementary ally placed in the "of T' position Overcurrent Protection. (3) Designed so that the circuit cannot be energized auto- matically after the device has been manually placed in (1) Without Motor or with Motor Not over 1/e Horse- the "off" position power. For fixed electric space-heating equipment without a motor rated over '/s hp, the branch-circuit switch or cir- (4) Located as specified in 424.19 cuit breaker shall be permitted to serve as the disconnecting (B) Thermostats That Do Not Directly Interrupt All means where the switch or circuit breaker is within sight Ungrounded Conductors.Thermostats that do not directly from the heater or is capable of being locked in the open interrupt all ungrounded conductors and thermostats that position. operate remote-control circuits shall not be required to meet (2) Over 1/e Horsepower. For motor-driven electric space- the requirements of 424.20(A). These devices shall not be heating equipment with a motor rated over 'Is hp, a discon- permitted as the disconnecting means. necting means shall be located within sight from the motor controller or shall be permitted to comply with the require- 424.21 Switch and Circuit Breaker to Be Indicating. ments in 424.19(A)(2). Switches and circuit breakers used as disconnecting means shall be of the indicating type. (C) Unit Switch(es) as Disconnecting Means. A unit switch(es) with a marked "off' position that is part of a 424.22 Overcurrent Protection. fixed heater and disconnects all ungrounded conductors shall be permitted as the disconnecting means required by (A) Branch-Circuit Devices. Electric space-heating this article where other means For disconnection are pro- equipment, other than such motor-operated equipment as vided in the types of occupancies in 424.19(C)(1) through required by Articles 430 and 440 to have additional over- current protection, shall be permitted to be protected (C)(4). against overcurrent where supplied by one of the branch (1) Multifamily Dwellings. In multifamily dwellings, the circuits in Article 210. other disconnecting means shall be within the dwelling unit, or on the same door as the dwelling unit in which the {B} Resistance Elements. Resistance-type heating ele- fixed heater is installed, and shall also be permitted to con- ments in electric space-heating equipment shall be pro- fixed lamps and appliances, tected at not more than 60 amperes. Equipment rated more than 48 amperes and employing such elements shall have (2) Two-Family Dwellings. In two-family dwellings, the the heating elements subdivided, and each subdivided load other disconnecting means shall be permitted either inside shall not exceed 48 amperes. Where a subdivided load is 2008 Edition NATIONAL ELECTRICAL CODE 70-285 424.28 ARTICLE 424--FIXED ELECTRIC SPACE-HEATING EQIIIPMEN'f less than 48 amperes, the rating of the supplementary over- IV. Marking of Heating Equipment current protective device shall comply with 424.3(B). A boiler employing resistance-type immersion heating ele- 424.28 Nameplate. ments contained in an ASME-rated and stamped vessel (A) Marking Required. Each unit of fixed electric space- shall be permitted to comply with 424.72(A). heating equipment shall be provided with a nameplate giv- (C) Overcurrent Protective Devices. The supplementary ing the identifying name and the normal rating in volts and overcurrent protective devices for the subdivided loads Watts or in volts and amperes. specified in 424.22(B) shall be (1) factory-installed within Electric space-heating equipment intended for use on or on the heater enclosure or supplied for use with the alternating current only or direct current only shall be heater as a separate assembly by the heater manufacturer; marked to so indicate. The marking of equipment consist- (2) accessible, but shall not be required to be readily acces- ing of motors over I/8 hp and other loads shall specify the sible; and (3) suitable for branch-circuit protection. rating of the motor in volts, amperes, and frequency, and FPN: See 240.10. the heating load in volts and watts or in volts and amperes. Where cartridge fuses are used to provide this overcur- (B) Location. This nameplate shall be located so as to be rent protection, a single disconnecting means shall be per- visible or easily accessible after installation. mitted to be used for the several subdivided loads. 424.29 Marking of Heating Elements. All heating eie- FPN No. I: For supplementary overcurrent protection, see ments that are replaceable in the field and are part of an 240.10. electric heater shall be legibly marked with the ratings in FPN No. 2: For disconnecting means for cartridge fuses in volts and watts or in volts and amperes. circuits of any voltage, see 240.40. (D) Branch-Circuit Conductors. The conductors supply- V. Electric Space-Heating Cables ing the supplementary overcurrent protective devices shall be considered branch-circuit conductors. 424.34 Heating Cable Construction. Heating cables shall Where the heaters are rated 50 kW or more, the con- be furnished complete with factory-assembled nonheating ductors supplying the supplementary overcurrent protective leads at least 2.1 m (7 ft) in length. devices specified in 424.22(C) shall be permitted to be sized at not less than 100 percent of the nameplate rating of 424.35 Marking of Heating Cables. Each unit shall be the heater, provided all of the following conditions are met: marked with the identifying name or identification symbol, (1) The heater is marked with a minimum conductor size. catalog number, and ratings in volts and watts or in volts (2) The conductors are not smaller than the marked mini- and amperes. mum size. Each unit length of heating cable shall have a perma- (3) A temperature-actuated device controls the cyclic op- nent legible marking on each nonheating lead located eration of the equipment. within 75 mm (3 in.) of the terminal end. The lead wire shall have the following color identification to indicate the (E) Conductors for Subdivided Loads. Field-wired con- circuit voltage on which it is to be used: ductors between the heater and the supplementary overcur- (1) 120 volt, nominal — yellow rent protective devices shall be sized at not less than (2) 208 volt, nominal — blue 125 percent of the load served.The supplementary overcur- rent protective devices specified in 424.22(C) shall protect (3) 240 volt, nominal —red these conductors in accordance with 240.4. (4) 277 volt, nominal — brown Where the heaters are rated 50 kW or more,the ampac- (5) 480 volt, nominal —orange ity of field-wired conductors between the heater and the supplementary overcurrent protective devices shall be per- 424.36 Clearances of Wiring in Ceilings. Wiring located mitted to be not less than 100 percent of the load of their above heated ceilings shall be spaced not less than 50 mm respective subdivided circuits, provided all of the following (2 in.) above the heated ceiling and shall be considered as conditions are met: operating at an ambient temperature of 50°C (122°F). The (1) The heater is marked with a minimum conductor size. ampacity of conductors shall be calculated on the basis of (2) The conductors are not smaller than the marked mini- the correction factors shown in the 0-2000 volt ampacity mum size. tables of Article 310. If this wiring is located above thermal (3) A temperature-activated device controls the cyclic op- insulation having a minimum thickness of 50 mm (2 in.), eration of the equipment, the wiring shalt not require correction for temperature. 70-286 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 424—FIXED ELECTRIC SPACE-HEATING EQUIPMENT 424.43 424.38 Area Restrictions. (D) Splices. All heating cables, the splice between the (A) Shall Not Extend Beyond the Room or Area. Heat- heating cable and nonheating Ieads, and 75-mm (3-in.) ing cables shall not extend beyond the room or area in minimum of the nonheating lead at the splice shall be em- which they originate. bedded in plaster or dry board in the same manner as the heating cable. (B) Uses Prohibited. Heating cables shall not be installed in the following: (E) Ceiling Surface. The entire ceiling surface shall have a finish of thermally noninsulating sand plaster that has a (1) In closets nominal thickness of 13 mm('/2 in.),or other noninsulating (2) Over walls material identified as suitable for this use and applied ac- (3) Over partitions that extend to the ceiling, unless they cording to specified thickness and directions. are isolated single runs of embedded cable (4) Over cabinets whose clearance from the ceiling is less (F) Secured. Cables shall be secured by means of ap- than the minimum horizontal dimension of the cabinet proved stapling, tape, plaster, nonmetallic spreaders, or to the nearest cabinet edge that is open to the room or other approved means either at intervals not exceeding area 400 mm (16 in.) or at intervals not exceeding 1.8 m (6 ft) for cables identified for such use. Staples or metal fasteners (C) In Closet Ceilings as Low-Temperature Heat that straddle the cable shall not be used with metal lath or Sources to Control Relative Humidity. The provisions of other electrically conductive surfaces. 424.38(B) shall not prevent the use of cable in closet ceil- ings as low-temperature heat sources to control relative hu- (G) Dry Board Installations. In dry board installations, midity, provided they are used only in those portions of the the entire ceiling below the heating cable shall be covered ceiling that are unobstructed to the floor by shelves or other with gypsum board not exceeding 13 mm (t/2 in.) thickness. permanent luminaires. The void between the upper layer of gypsum board, plaster lath, or other fire-resistant material and the surface layer of 424.39 Clearance from Other Objects and Openings. gypsum board shall be completely filled with thermally Heating elements of cables shall be separated at least 200 mm conductive,nonshrinking plaster or other approved material (8 in.) from the edge of outlet boxes and junction boxes that or equivalent thermal conductivity. are to be used for mounting surface luminaires.A clearance of not less than 50 mm (2 in.) shall be provided from recessed (H) Free from Contact with Conductive Surfaces. luminaires and their trims, ventilating openings, and other Cables shall be kept free from contact with metal or other such openings in room surfaces. Sufficient area shall be pro- electrically conductive surfaces. vided to ensure that no heating cable is covered by any (I) Joists. In dry board applications, cable shall be in- surface-mounted units. stalled parallel to the joist, leaving a clear space centered 424.40 Splices. Embedded cables shall be spliced only under the joist of 65 mm (2'/2 in.) (width) between centers where necessary and only by approved means, and in no of adjacent runs of cable. A surface layer of gypsum board case shall the length of the heating cable be altered. shall be mounted so that the nails or other fasteners do not pierce the heating cable. 424.41 Installation of Heating Cables on Dry Board, in Plaster, and on Concrete Ceilings. (J) Crossing Joists. Cables shall cross joists only at the ends of the room unless the cable is required to cross joists (A) In Walls. Cables shall not be installed in walls unless elsewhere in order to satisfy the manufacturer's instructions it is necessary for an isolated single run of cable to be that the installer avoid placing the cable too close to ceiling installed down a vertical surface to reach a dropped ceiling. penetrations and luminaires. (B) Adjacent Runs. Adjacent runs of cable not exceeding 424.42 Finished Ceilings. Finished ceilings shall not be 9 watts/m (23/4 watts/ft) shall not be installed less than covered with decorative panels or beams constructed of 38 mm (1'/2 in.) on centers. p materials that have thermal insulating properties, such as (C) Surfaces to Be Applied. Heating cables shall be ap- wood, fiber, or plastic. Finished ceilings shall be permitted plied only to gypsum board, plaster lath, or other fire- to be covered with paint, wallpaper, or other approved sur- resistant material. With metal lath or other electrically con- face finishes. ductive surfaces, a coat of plaster shall be applied to completely separate the metal lath or conductive surface 424.43 Installation of Nonheating Leads of Cables. from the cable. (A) Free Nonheating Leads. Free nonheating leads of FPN: See also 424.410. cables shall be installed in accordance with approved wiring 2008 Edition NATIONAL ELECTRICAL CODE 70-287 424.44 ARTICLE 424—FIXED ELECTRIC SPACE-HEATING EQUIPMENT methods from the junction box to a location within the ceiling. VI. Duct Heaters Such installations shall be permitted to be single conductors in approved raceways, single or multiconductor Type UF, Type 424.57 General.Part VI shall apply to any heater mounted NMC,Type MI, or other approved conductors. in the airstream of a forced-air system where the air- moving unit is not provided as an integral part of the equip- (B) Leads in Junction Box. Not less than 150 mm (6 in.) ment. of free nonheating lead shall be within the junction box. The marking of the leads shall be visible in the junction 424.58 Identification. Heaters installed in an air duct shall box. be identified as suitable for the installation. (C) Excess Leads. Excess leads of heating cables shall not 424.59 Airflow. Means shall be provided to ensure uni- be cut but shall he secured to the underside of the ceiling form and adequate airflow over the face of the heater in and embedded in plaster or other approved material, leav- accordance with the manufacturer's instructions. ing only a length sufficient to reach the junction box with not less than 150 mm (6 in.) of free lead within the box. FPN: Heaters installed within 1.2 m (4 ft) of the outlet of an air-moving device, heat pump, air conditioner, elbows, baffle plates,or other obstructions in ductwork may require 424.44 Installation of Cables in Concrete or Poured turning vanes, pressure plates, or other devices on the inlet Masonry Floors. side (if the duct heater to ensure an even distribution of air (A) Watts per Linear Meter (Foot). Constant wattage over the face of the heater. heating cables shall not exceed 54 watts/linear meter 424.60 Elevated Inlet Temperature. Duct heaters in- (t61/2 watts/linear foot) of cable. tended for use with elevated inlet air temperature shall be (B) Spacing Between Adjacent Runs. The spacing be- identified as suitable for use at the elevated temperatures. tween adjacent runs of cable shall not be less than 25 mm (1 in.) on centers. 424.61 Installation of Duct Heaters with Heat Pumps and Air Conditioners. Heat pumps and air conditioners (C) Secured in Place. Cables shall be secured in place by having duct heaters closer than 1.2 m (4 ft) to the heat nonmetallic frames or spreaders or other approved means pump or air conditioner shall have both the duct heater and while the concrete or other finish is applied. heat pump or air conditioner identified as suitable for such Cables shall not be installed where they bridge expan- installation and so marked. sion joints unless protected from expansion and contrac- tion. 424.62 Condensation. Duct heaters used with air condi- tioners or other air-cooling equipment that could result in (D) Spacings Between Heating Cable and Metal Em- condensation of moisture shall be identified as suitable for bedded in the Floor.Spacings shall be maintained between use with air conditioners. the heating cable and metal embedded is the floor, unless the cable is a grounded metal-clad cable. 424.63 Fan Circuit Interlock. Means shall be provided to ensure that the fan circuit is energized when any heater circuit (E) Leads Protected. Leads shall be protected where they leave the floor by rigid metal conduit, intermediate meta] is energized. However, time- or temperature-controlled delay conduit, rigid nonmetallic conduit, electrical metallic tub- in energizing the fan motor shall be permitted, ing, or by other approved means. 424.64 Limit Controls. Each duct heater shall be provided (F) Bushings or Approved Fittings. Bushings or ap- with an approved, integral, automatic-reset temperature- proved fittings shall be used where the leads emerge within limiting control or controllers to de-energize the circuit or the floor slab. circuits. In addition, an integral independent supplementary con- (G) Ground-Fault Circuit-Interrupter Protection. trol or controllers shall be provided in each duct heater that Ground-fault circuit-interrupter protection for personnel disconnects a sufficient number of conductors to interrupt shall be provided for cables installed in electrically heated current flow. This device shalt be manually resettable or floors of bathrooms and in hydromassage bathtub locations. replaceable. 424.45 Inspection and Tests. Cable installations shall be 424.65 Location of Disconnecting Means. Duct heater made with due care to prevent damage to the cable assem- controller equipment shall be either accessible with the dis- bly and shall be inspected and approved before cables are connecting means installed at or within sight from the con- covered or concealed. troller or as permitted by 424.19(A). 70-288 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 424—FIXED ELECTRIC SPACE-HEATING EQUIPMENT 424.74 424.66 Installation. Duct heaters shall be installed in ac- (1) Factory-installed within or on the boiler enclosure cordance with the manufacturer's instructions in such a or provided as a separate assembly by the boiler manner that operation does not create a hazard to persons manufacturer or property. Furthermore, duct heaters shall be located with (2) Accessible, but need not be readily accessible respect to building construction and other equipment so as (3) Suitable for branch-circuit protection to permit access to the heater. Sufficient clearance shall be maintained to permit replacement of controls and heating Where cartridge fuses are used to provide this overcur- elements and for adjusting and cleaning of controls and rent protection, a single disconnecting means shall be per- other parts requiring such attention. See 110.26, mitted for the several subdivided circuits. See 240.40. FPN: For additional installation information, see (D) Conductors Supplying Supplementary Overcurrent NFPA 90A-2002, Standard for the Installation of Air- Protective Devices. The conductors supplying these Conditioning and Ventilating Systetns, and NFPA 90B- supplementary overcurrent protective devices shall be con- 2006, Standard for the Installation of Wann Air Healing sidered branch-circuit conductors. and Air-Conditioning S wtents. Where the heaters are rated 50 kW or more, the con- ductors supplying the overcurrent protective device speci- VII. Resistance-Type Boilers fied in 424.72(C) shall be permitted to be sized at not less 424.70 Scope. The provisions in Part VII of this article than 100 percent of the nameplate rating of the heater, shall apply to boilers employing resistance-type heating el- provided all of the following conditions are met: ements. Electrode-type boilers shall not be considered as (1) The heater is marked with a minimum conductor size. employing resistance-type heating elements. See Part VIII (2) The conductors are not smaller than the marked mini- of this article. mum size. (3) A temperature-or pressure-actuated device controls the 424.71 Identification. Resistance-type boilers shall be cyclic operation of the equipment, identified as suitable for the installation. (E) Conductors for Subdivided Loads. Field-wired con- 424.72 Overcurrent Protection. ductors between the heater and the supplementary overcur- rent protective devices shall be sized at not less than (A) Boiler Employing Resistance-Type Immersion ]25 percent of the load served. The supplementary overcur- rent protective devices specified in 424.72(C) shall protect sel. A boiler employing resistance-type immersion heating these conductors in accordance with 240.4. elements contained in an ASME-rated and stamped vessel Where the heaters are rated 50 kW or more, the ampac- shall have the heating elements protected at not more than ity of field-wired conductors between the heater and the 150 amperes. Such a boiler rated more than 120 amperes supplementary overcurrent protective devices shall be per- shall have the heating elements subdivided into loads not mitted to be not less than 100 percent of the load of their exceeding 120 amperes. respective subdivided circuits,provided all of the following Where a subdivided load is less than 120 amperes, the conditions are met: rating of the overcurrent protective device shall comply with 424.3(B). (1) The heater is marked with a minimum conductor size. (2) The conductors are not smaller than the marked mini- (B) Boiler Employing Resistance-Type Heating Ele- mum size. menns Rated More Than 48 Amperes and Not Con- (3) A temperature-activated device controls the cyclic op- tained in an ASME-Rated and Stamped Vessel. A boiler eration of the equipment. employing resistance-type heating elements not contained in an ASME-rated and stamped vessel shall have the heat- 424.73 Overtemperature Limit Control. Each boiler Be- ing elements protected at not more than 60 amperes. Such a signed so that in normal operation there is no change in boiler rated more than 48 amperes shall have the heating state of the heat transfer medium shall be equipped with a elements subdivided into loads not exceeding 48 amperes. temperature-sensitive limiting means. It shall be installed to Where a subdivided load is less than 48 amperes, the limit maximum liquid temperature and shall directly or in- rating of the overcurrent protective device shall comply directly disconnect all ungrounded conductors to the heat- with 424.3(B). ing elements. Such means shall be in addition to a temperature-regulating system and other devices protecting (C) Supplementary Overcurrent Protective Devices. the tank against excessive pressure. The supplementary overcurrent protective devices for the subdivided loads as required by 424.72(A) and (B) shall be 424.74 Overpressure Limit Control, Each boiler de- as follows: signed so that in normal operation there is a change in state 2008 Edition NATIONAL.ELECTRICAL CODE 70-,259 424.80 ARTICLE 424—FIXED ELECTRIC SPACE-HEATING EQUIPMENT of the heat transfer medium from liquid to vapor shall be be installed to limit maximum pressure and shall directly or equipped with a pressure-sensitive limiting means. It shalt indirectly interrupt all current flow through the electrodes. be installed to limit maximum pressure and shall directly or Such means sha11 be in addition to a pressure-regulating indirectly disconnect all ungrounded conductors to the system and other devices protecting the tank against exces- heating elements. Such means shall be in addition to a sive pressure. pressure-regulating system and other devices protecting the tank against excessive pressure. 424.85 Grounding. For those boilers designed such that fault currents do not pass through the pressure vessel, and the pressure vessel is electrically isolated from the elec- VIII. Electrode-Type Boilers trodes, all exposed non—current-carrying metal parts, in- 424.80 Scope. The provisions in Part VIII of this article cluding the pressure vessel, supply, and return connecting shall apply to boilers for operation at 600 volts, nominal,or piping, shall be grounded. less, in which heat is generated by the passage of current For all other designs, the pressure vessel containing the between electrodes through the liquid being heated. electrodes shall be isolated and electrically insulated from ground. FPN: For over 600 volts, see Part V of Article 490. 424.86 Markings. All electrode-type boilers shall be 424.81 Identification.Electrode-type boilers shall be iden- marked to show the following: tified as suitable for the installation. (I) The manufacturer's name 424.82 Branch-Circuit Requirements. The size of (2) The normal rating in volts, amperes, and kilowatts branch-circuit conductors and overcurrent protective de- (3) The electrical supply required specifying frequency, vices shall be calculated on the basis of 125 percent of the number of phases, and number of wires total load(motors not included).A contactor, relay,or other (4) The marking "Electrode-Type Boiler" device, approved for continuous operation at 100 percent of (5) A warning marking, "All Power Supplies Shall Be Dis- its rating, shall be permitted to supply its full-rated load. connected Before Servicing, Including Servicing the See 210.19(A), Exception. The provisions of this section Pressure Vessel" shall not apply to conductors that form an integral part of The nameplate shall be located so as to be visible after an approved boiler. Where an electrode boiler is rated 50 kW or more, the installation. conductors supplying the boiler electrode(s) shall be per- mitted to be sized at not less than 100 percent of the name- IX. Electric Radiant Heating Panels and Heating plate rating of the electrode boiler, provided all the follow- Panel Sets ing conditions are met: (I) The electrode boiler is marked with a minimum con- 424.90 Scope. The provisions of Part IX of this article shall apply to radiant heating panels and heating panel sets. doctor size. (2) The conductors are not smaller than the marked mini- 424.91 Definitions. mum size. (3) A temperature- or pressure-actuated device controls the Heating Panel.A complete assembly provided with a junc- cyclic operation of the equipment. tion box or a length of flexible conduit for connection to a branch circuit. 424.83 Overtemperature Limit Control. Each boiler, de- Heating Panel Set. A rigid or nonrigid assembly provided signed so that in normal operation there is no change in with nonheating leads or a terminal junction assembly iden- state of the heat transfer medium, shall be equipped with a tified as being suitable for connection to a wiring system. temperature-sensitive limiting means. It shall be installed to limit maximum liquid temperature and shall directly or in- 424.92 Markings. directly interrupt all current flow through the electrodes. Such means shall be in addition to the temperature- (A) Location. Markings shall be permanent and in a loca- tion that is visible prior to application of panel finish. regulating system and other devices protecting the tank against excessive pressure. (B) Identified as Suitable. Each unit shall be identified as suitable for the installation. 424.84 Overpressure Limit Control. Each boiler, de- signed so that in normal operation there is a change in state (C) Required Markings. Each unit shall be marked with of the heat transfer medium from Iiquid to vapor, shall be the identifying name or identification symbol,catalog num- equipped with a pressure-sensitive limiting means. It shall ber, and rating in volts and watts or in volts and amperes. 70-290 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 424—FIXED ELECTRIC SPACE,HEATING EQUIPMENT 424.95 (D) Labels Provided by Manufacturer. The manufactur- (2)Parallel to joists or Nailing Strips. Heating panel sets ers of heating panels or heating panel sets shall provide shall be installed parallel to joists or nailing strips. marking labels that indicate that the space-heating installa- tion incorporates heating panels or heating panel sets and (3) Installation of Nails, Staples, or Other Fasteners. instructions that the labels shall be affixed to the panel- Nailing or stapling of heating panel sets shall be done only boards to identify which branch circuits supply the circuits through the unheated portions provided for this purpose. to those space-heating installations. If the heating panels Heating panel sets shall not be cut through or nailed and heating panel set installations are visible and distin- through any point closer than 6 mm (1/4 in.) to the element. guishable after installation, the labels shall not be required Nails, staples, or other fasteners shall not be used where to be provided and affixed to the panelboards. they penetrate current-carrying parts. 424.93 Installation. (4)installed as Complete Unit. Heating panel sets shall be installed as complete units unless identified as suitable for (A) General. field cutting in an approved manner. (1)Manufacturer's Instructions.Heating panels and heat- ing panel sets shall be installed in accordance with the 424.94 Clearances of Wiring in Ceilings. Wiring located manufacturer's instructions. above heated ceilings shall be spaced not less than 50 mm (2) Locations Not Permitted.The heating portion shall not (2 In.) above the heated ceiling and shall be considered as be installed as follows: operating at an ambient of 50°C (1227). The ampacity s (1) In or behind surfaces where subject to physical damae hall be calculated on the basis of the correction factors g given in the 0-2000 volt ampacity tables of Article 310. If (2) Run through or above walls, partitions, cupboards, or this wiring is located above thermal insulations having a similar portions of structures that extend to the ceiling minimum thickness of 50 mm (2 in.), the wiring shall not (3) Run in or through thermal insulation, but shall be per- require correction for temperature. mitted to be in contact with the surface of thermal insulation 424.95 Location of Branch-Circuit and Feeder Wiring (3) Separation from Outlets for Luminaires. Edges of in Walls. panels and panel sets shall be separated by not less than (A) Exterior Walls. Wiring methods shall comply with 200 mm (8 in.) from the edges of any outlet boxes and Article 300 and 310.10. junction boxes that are to be used for mounting surface lumi- naires. A clearance of not less than 50 mm (2 in.) shall be (B) Interior Walls. Any wiring behind heating panels or provided from recessed luminaires and their trims, ventilating heating panel sets located in interior walls or partitions openings, and other such openings in room surfaces, unless shall be considered as operating at an ambient temperature the heating panels and panel sets are listed and marked for of 40°C (104°F), and the ampacity shall be calculated on lesser clearances, in which case they shall be permitted to be the basis of the correction factors given in the 0-2000 volt installed at the marked clearances. Sufficient area shall be pro- ampacity tables of Article 310, vided to ensure that no heating panel or heating panel set is to be covered by any surface-mounted units. 424.96 Connection to Branch-Circuit Conductors. (4) Surfaces Covering Heating Panels. After the heating (A) General. Heating panels or heating panel sets as- panels or heating panel sets are installed and inspected, it sembled together in the field to form a heating installation shall be permitted to install a surface that has been identi- in one room or area shall be connected in accordance with fied by the manufacturer's instructions as being suitable for the manufacturer's instructions. the installation. The surface shall be secured so that the nails or other fastenings do not pierce the heating panels or (B) Heating Panels. Heating panels shall be connected to heating panel sets. branch-circuit wiring by an approved wiring method. (5) Surface Coverings. Surfaces permitted by (C) Heating Panel Sets. 424.93(A)(4) shall be permitted to be covered with paint, wallpaper, or other approved surfaces identified in the (1) Connection to Branch-Circuit Wiring. Heating panel manufacturer's instructions as being suitable, sets shall be connected to branch-circuit wiring by a (B) Heating Panel Sets. method identified as being suitable for the purpose. (1) Mounting Location. Heating panel sets shall be per- (2) Panel Sets with Terminal Junction Assembly. A mitted to be secured to the lower face of joists or mounted heating panel set provided with terminal junction assem- in between joists, headers, or nailing strips, bly shall be permitted to have the nonheating leads 2008 Edition NATIONAL ELECTRICAL CODE 70-,291 424.97 ARTICLE 426—FIXED OUTDOOR ELECTRIC DEICING AND SNOW-MELTING EQUIPMENT attached at the time of installation in accordance with the (1) Expansion Joints. Heating panels or heating panel sets manufacturer's instructions. shall not be installed where they bridge expansion joints unless protected from expansion and contraction. 424.97 Nonheating Leads. Excess nonheating leads of heating panels or heating panel sets shall be permitted to be (2) Connection to Conductors. Heating panels and heat- cut to the required length. They shat] meet the installation mg panel sets shall be connected to branch-circuit and sup- requirements of the wiring method employed in accordance ply wiring by wiring methods recognized in Chapter 3. with 424.96. Nonheating leads shall be an integral part of a (3) Anchoring.Heating panels and heating panel sets shall heating panel and a heating panel set and shall not be sub- be firmly anchored to the floor using an adhesive or anchor- jected to the ampacity requirements of 424.3(B) for branch ing system identified for this use. circuits. (4) Coverings. After heating panels or heating panel sets 424.98 Installation in Concrete or Poured Masonry. are installed and inspected, they shall be permitted to be covered by a floor covering that has been identified by the (A) Maximum Heated Area. Heating panels or heating manufacturer as being suitable for the installation.The cov- panel sets shall not exceed 355 watts/M2 (33 wattslft2) of ering shall be secured to the heating panel or heating panel heated area. sets with release-type adhesives or by means identified for this use. (B) Secured in Place and Identified as Suitable. Heating panels or heating panel sets shall be secured in place by (5) Fault Protection. A device to open all ungrounded means specified in the manufacturer's instructions and conductors supplying the heating panels or heating panel identified as suitable for the installation. sets, provided by the manufacturer, shall function when a low- or high-resistance line-to-line, line-to-grounded con- (C) Expansion Joints. Heating panels or heating panel sets ductor, or line-to-ground fault occurs, such as the result of shall not be installed where they bridge expansion joints un- a penetration of the element or element assembly. less provision is made for expansion and contraction. FPN: An integral grounding shield may be required to pro- vide this protection. (D) Spacings. Spacings shall be maintained between heat- ing panels or heating panel sets and metal embedded in the floor. Grounded metal-clad heating panels shall be permit- ted to be in contact with metal embedded in the floor. ARTICLE 426 (E) Protection of Leads. Leads shall be protected where Fixed Outdoor Electric Deicing they leave the floor by rigid metal conduit, intermediate metal conduit, rigid nonmetallic conduit, or electrical me- tallic tubing, or by other approved means. 1. General (F) Bushings or Fittings Required.Bushings or approved fittings shall be used where the leads emerge within the 426.1 Scope.The requirements of this article shall apply to floor slabs. electrically energized heating systems and the installation of these systems. 424.99 Installation Under Floor Covering. (A) Embedded.Embedded in driveways,walks, steps, and (A) Identification. Heating panels or heating panel sets for other areas. installation under floor covering shall be identified as suit- able for installation under floor covering. (B) Exposed. Exposed on drainage systems, bridge struc- tures, roofs, and other structures. (B) Maximum Heated Area. Heating panels or panel sets installed under floor covering shall not exceed 160 watts/m2 426.2 Definitions. (15 wattslft2) of heated area. Heating System. A complete system consisting of compo- (C) Installation. Listed heating panels or panel sets, if in- nents such as heating elements, fastening devices, nonheat- stailed under floor covering, shall be installed on floor sur- ing circuit wiring, leads, temperature controllers, safety faces that are smooth and flat in accordance with the manu- signs,junction boxes, raceways, and fittings. facturer's instructions and shall also comply with Impedance Heating System. A system in which heat is 424.99(C)(1) through (C)(5). generated in a pipe or rod, or combination of pipes and 70-292 RATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 426—FIXED OUTDOOR ELECTRIC DEICING AND SNOW-MELTING EQUIPMENT 426.22 rods, by causing current to flow through the pipe or rod by tion or installation other than covered by this article shall direct connection to an ac voltage source from a dual- be permitted only by special permission. winding transformer. The pipe or rod shall be permitted to be embedded in the surface to be heated, or constitute the III. Resistance Heating Elements exposed components to be heated. Resistance Heating Element. A specific separate element 426.20 Embedded Deicing and Snow-Melting Equipment. to generate heat that is embedded in or fastened to the (A) Watt Density. Panels or units shall not exceed 1300 surface to be heated, watts/m` (120 watts/ft`) of heated area. FPN: Tubular heaters, strip heaters, heating cable, heating (B) Spacing. The spacing between adjacent cable runs is tape,and heating panels are examples of resistance heaters. dependent upon the rating of the cable and shall be not less Skin-Effect Heating System. A system in which heat is than 25 mm (I in.) on centers. generated on the inner surface of a ferromagnetic envelope (C) Cover. Units, panels, or cables shall be installed as embedded in or fastened to the surface to be heated. follows: FPN: Typically, an electrically insulated conductor is (1) On a substantial asphalt or masonry base at least routed through and connected to the envelope at the other 50 mm(2 in.)thick and have at least 38 mm(11/2 in.)of end. The envelope and the electrically insulated conductor asphalt or masonry applied over the units, panels, or are connected to an ac voltage source from a dual-winding cables; or transformer. (2) They shall be permitted to be installed over other ap- 426.3 Application of Other Articles. Cord-and-plug- proved bases and embedded within 90 mm (3'/z in.) of connected fixed outdoor electric deicing and snow-melting masonry or asphalt but not less than 38 mm (11/2 in.) equipment intended for specific use and identified as suit- from the top surface; or able for this use shall be installed according to Article 422. (3) Equipment that has been specially investigated for other forms of installation shall be installed only in the 426.4 Continuous Load. Fixed outdoor electric deicing manner for which it has been investigated, and snow-melting equipment shall be considered as a con- tinuous load. (D) Secured. Cables, units, and panels shall be secured in place by frames or spreaders or other approved means II. installation while the masonry or asphalt finish is applied. 426.10 General. Equipment for outdoor electric deicing (E) Expansion and Contraction. Cables, units, and pan- and snow melting shall be identified as being suitable For els shall not be installed where they bridge expansion joints the Following: unless provision is made for expansion and contraction. (1) The chemical, thermal, and physical environment 426.21 Exposed Deicing and Snow-Melting Equipment. (2) Installation in accordance with the manufacturer's (A) Secured. Heating element assemblies shall be secured drawings and instructions to the surface being heated by approved means. 426.11 Use. Electric heating equipment shall be installed (B) Overtemperature. Where the heating element is not in such a manner as to be afforded protection from physical in direct contact with the surface being heated, the design damage. of the heater assembly shall be such that its temperature 426.12 Thermal Protection. External surfaces of outdoor limitations shall not be exceeded. electric deicing and snow-melting equipment that operate at (C) Expansion and Contraction. Heating elements and temperatures exceeding 60°C (140°F) shall be physically assemblies shall not be installed where they bridge expansion guarded, isolated, or thermally insulated to protect against joints unless provision is made for expansion and contraction. contact by personnel in the area. (D) Flexural Capability. Where installed on flexible 426.13 Identification.The presence of outdoor electric de- structures, the heating elements and assemblies shall have a icing and snow-melting equipment shall be evident by the flexural capability that is compatible with the structure, posting of appropriate caution signs or markings where 426.22 Installation of Nonheating Leads for Embedded clearly visible. Equipment. 426.14 Special Permission. Fixed outdoor deicing and (A) Grounding Sheath or Braid. Nonheating leads hav- snow-melting equipment employing methods of construc- ing a grounding sheath or braid shall be permitted to be 2008 Edition NATIONAL ELECTRICAL CODE 70-293 426.23 ARTICLE 426—FIXED OUTDOOR ELECTRIC DEICING AND SNOW-MELTING EQUIPMENT embedded in the masonry or asphalt in the same manner as 426.26 Corrosion Protection. Ferrous and nonferrous the heating cable without additional physical protection. metal raceways, cable armor, cable sheaths, boxes, fittings, supports, and support hardware shall be permitted to be (B) Raceways.All but 25 mm to 150 mm(1 in. to 6 in.) of installed in concrete or in direct contact with the earth, or in nonheating leads of Type TW and other approved types not areas subject to severe corrosive influences, where made of having a grounding sheath shall be enclosed in a rigid con- material suitable for the condition, or where provided with duit, electrical metallic tubing, intermediate metal conduit, corrosion protection identified as suitable for the condition. or other raceways within asphalt or masonry; and the dis- tance from the factory splice to raceway shall not be less 426.27 Grounding Braid or Sheath. Grounding means, than 25 mm (1 in.) or more than 150 mm (6 in.). such as copper braid, metal sheath, or other approved (C) Bushings. Insulating bushings shall be used in the as- means,shall be provided as part of the heated section of the phalt or masonry where leads enter conduit or tubing. cable, panel, or unit. (D) Expansion and Contraction. Leads shall be protected 426.28 Equipment Protection. Ground-fault protection of in expansion joints and where they emerge from masonry equipment shall be provided for fixed outdoor electric de- or asphalt by rigid conduit, electrical metallic tubing, inter- icing and snow-melting equipment, except for equipment mediate metal conduit, other raceways, or other approved that employs mineral-insulated, metal-sheathed cable em- means. bedded in a noncombustible medium. (E) Leads in Junction Boxes. Not less than 150 mm 1V. Impedance Heating (6 in.) of free nonheating lead shall be within the junction box. 426.30 Personnel Protection. Exposed elements of im- pedance heating systems shall be physically guarded, iso- 426.23 Installation of Nonheating Leads for Exposed lated, or thermally insulated with a weatherproof jacket to Equipment. protect against contact by personnel in the area. (A) Nonheating Leads. Power supply nonheating leads (cold leads) for resistance elements shall be suitable for the 426.31 Isolation Transformer. A dual-winding trans- temperature encountered. Not less than 150 mm (6 in.) of former with a grounded shield between the primary and nonheating leads shall be provided within the junction box, secondary windings shall be used to isolate the distribution Preassembled factory-supplied and field-assembled non- system from the heating system. heating leads on approved heaters shall be permitted to be shortened if the markings specified in 426.25 are retained. 426.32 Voltage Limitations. Unless protected by ground- fault circuit-interrupter protection for personnel, the see- (B) Protection. Nonheating power supply leads shall be ondary winding of the isolation transformer connected to enclosed in a rigid conduit, intermediate metal conduit, the impedance heating elements shall not have an output electrical metallic tubing, or other approved means. voltage greater than 30 volts ac. Where ground-fault circuit-interrupter protection for 426.24 Electrical Connection. personnel is provided, the voltage shall be permitted to be (A) Heating Element Connections. Electrical connec- greater than 30 but not more than 80 volts. tions, other than factory connections of heating elements to 426.33 Induced Currents. All current-carrying compo- nonheating elements embedded in masonry or asphalt or on nents shall be installed in accordance with 300.20. exposed surfaces, shall be made with insulated connectors identified for the use. 426.34 Grounding. An impedance heating system that is (B) Circuit Connections. Splices and terminations at the operating at a voltage greater than 30 but not more than 80 end of the nonheating leads, other than the heating element shall be grounded at a designated point(s). end, shall be installed in a box or fitting in accordance with 110.14 and 300.15. V. Skin-Effect Heating 426.25 Marking. Each factory-assembled heating unit 426.40 Conductor Ampacity. The current through the shall be legibly marked within 75 mm(3 in.) of each end of electrically insulated conductor inside the ferromagnetic the nonheating leads with the permanent identification sym- envelope shall be permitted to exceed the ampacity values bol, catalog number, and ratings in volts and watts or in shown in Article 310, provided it is identified as suitable volts and amperes. for this use. 70-294 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 427—FIXED ELECTRIC HEATING EQUIPMENT FOR PIPELINES AND VESSELS 427,2 426.41 Pull Boxes. Where pull boxes are used, they shall (B) Temperature Controller Without `°Ofi'" Position. be accessible without excavation by location in suitable Temperature controlled switching devices that do not have vaults or abovegrade. Outdoor pull boxes shall be of water- an "off" position shall not be required to open all un- tight construction. grounded conductors and shall not be permitted to serve as the disconnecting means. 426.42 Single Conductor in Enclosure.The provisions of 300.20 shall not apply to the installation of a single con- (C) Remote Temperature Controller. Remote controlled ductor in a ferromagnetic envelope (metal enclosure). temperature-actuated devices shall not be required to meet the requirements of 426.51(A). These devices shall not be 426.43 Corrosion Protection. Ferromagnetic envelopes, permitted to serve as the disconnecting means. ferrous or nonferrous metal raceways, boxes, fittings, sup- ports, and support hardware shall be permitted to be in- (D) Combined Switching Devices. Switching devices stalled in concrete or in direct contact with the earth, or in consisting of combined temperature-actuated devices and areas subjected to severe corrosive influences, where made manually controlled switches that serve both as the control- of material suitable for the condition, or where provided ler and the disconnecting means shall comply with all of with corrosion protection identified as suitable for the con- the following conditions: dition. Corrosion protection shall maintain the original wall (1) Open all ungrounded conductors when manually placed thickness of the ferromagnetic envelope. in the "off"' position (2) Be so designed that the circuit cannot be energized 426.44 Grounding. The ferromagnetic envelope shall be automatically if the device has been manually placed in connected to an equipment grounding conductor at both the "off' position ends; and, in addition, it shall be permitted to be connected (3) Be capable of being locked in the open position to an equipment grounding conductor at intermediate points as required by its design. 426.54 Card-and-Plug-Connected Deicing and Snow- The provisions of 250.30 shall not apply to the instal- Melting Equipment. Cord-and-plug-connected deicing lation of skin-effect heating systems, and snow-melting equipment shall be listed. FPN: For grounding methods, see Article 250. VI. Control and Protection ARTICLE 427 426.50 Disconnecting Means. Fixed Electric Heating Equipment (A) Disconnection. All fixed outdoor deicing and snow- for Pipelines and Vessels melting equipment shall be provided with a means for si- multaneous disconnection from all ungrounded conductors. Where readily accessible to the user of the equipment, the I. General branch-circuit switch or circuit breaker shall be permitted 427.1 Scope.The requirements of this article shall apply to to serve as the disconnecting means. The disconnecting electrically energized heating systems and the installation means shall be of the indicating type and be provided with of these systems used with pipelines or vessels or both. a positive lockout in the "off' position. FPN: For further information, see ANSWEEE Std. 515- (B) Cord-and-Plug-Connected Equipment. The factory- 2002. Standard.for the Testing, Design. Installation and installed attachment plug of cord-and-plug-connected Maintenance of Electrical Resistance Heat Tracing for ht- equipment rated 20 amperes or less and 150 volts or less to dustrial Applications; ANSMEEE Std. 844-2000, Recoin- tnended Practice for Electrical Impedance, Induction, and ground shall be permitted to be the disconnecting means. Skin Effect Heating of Pipelines and Vessels; and ANSIINECA 202-2001,Recommended Practice for Install- 426.51 Controllers. ing and Maintaining Industrial Heat Tracing Systems. (A) Temperature Controller with "OV Position. Tem- 427.2 Definitions. perature controlled switching devices that indicate an "off' position and that interrupt line current shall open all un- Impedance Heating System. A system in which heat is grounded conductors when the control device is in the "off„ generated in a pipeline or vessel wall by causing current to position. These devices shall not be permitted to serve as flow through the pipeline or vessel wall by direct connec- the disconnecting means unless capable of being locked in tion to an ac voltage source from a dual-winding trans- the open position. farmer. 2008 Edition NATIONAL ELECTRICAL CODE 70-295 427.3 ARTICLE 427--FIXED ELECTRIC HEATING EQUIPMENT FOR PIPELINES AND VESSELS Induction Heating System.A system in which heat is gen- exceeding 60°C (140°F) shall be physically guarded, iso- erated in a pipeline or vessel wall by inducing current and lated, or thermally insulated to protect against contact by hysteresis effect in the pipeline or vessel wall from an ex- personnel in the area. ternal isolated ac field source. Integrated Heating System. A complete system consisting 427.13 Identification. The presence of electrically heated of components such as pipelines, vessels, heating elements, pipelines, vessels, or both, shall be evident by the posting heat transfer medium, thermal insulation, moisture barrier, of appropriate caution signs or markings at intervals not nonheating leads, temperature controllers, safety signs, exceeding 6 m(20 ft)along the pipeline or vessel:and on or junction boxes, raceways, and fittings. adjacent to equipment in the piping system that requires periodic servicing. Pipeline. A length of pipe including pumps,valves,flanges, control devices,strainers, and/or similar equipment for con- III. Resistance Heating Elements veying fluids. Resistance Heating Element. A specific separate element 427.14 Secured. Heating element assemblies shall be Se- to generate heat that is applied to the pipeline or vessel cured to the surface being heated by means other than the externally or internally. thermal insulation. FPN: Tubular heaters, strip heaters, heating cable, heating 427.15 Not in Direct Contact.Where the heating element tape,heating blankets, and immersion heaters are examples of resistance heaters. is not in direct contact with the pipeline or vessel being heated,means shall be provided to prevent overtemperature Skin-Effect Heating System. A system in which heat is of the heating element unless the design of the heater as- generated on the inner surface of a ferromagnetic envelope sembly is such that its temperature limitations will not be attached to a pipeline or vessel, or both, exceeded. FPN: Typically, an electrically insulated conductor is routed through and connected to the envelope at the other 427.16 Expansion and Contraction. Heating elements end.The envelope and the electrically insulated conductor and assemblies shall not be installed where they bridge are connected to an ac voltage source from a dual-winding expansion joints unless provisions are made for expansion transformer. and contraction. Vessel. A container such as a barrel, drum, or tank for holding fluids or other material. 427.17 Flexural Capability. Where installed on flexible pipelines, the heating elements and assemblies shall have a 427.3 Application of Other Articles. Card-connected flexural capability that is compatible with the pipeline. pipe heating assemblies intended for specific use and iden- tified as suitable for this use shall be installed according to 427,18 Power Supply Leads. Article 422. (A) Nonheating Leads. Power supply nonheating leads 427.4 Continuous Load.Fixed electric heating equipment (cold leads) for resistance elements shall be suitable for the for pipelines and vessels shall be considered continuous temperature encountered. Not less than 150 mm (6 in.) of load, nonheating leads shall be provided within the junction box. Preassembled factory-supplied and field-assembled non- I1. Installation heating leads on approved heaters shall be permitted to be shortened if the markings specified in 427.20 are retained. 427.10 General. Equipment for pipeline and vessel elec- tric heating shall be identified as being suitable for (1) the (B) Power Supply Leads Protection. Nonheating power chemical, thermal, and physical environment and(2) instal- supply leads shall be protected where they emerge from lation in accordance with the manufacturer's drawings and electrically heated pipeline or vessel heating units by rigid instructions. metal conduit, intermediate metal conduit, electrical metal- lic tubing, or other raceways identified as suitable for the 427.11 Use. Electric heating equipment shall be installed application. in such a manner as to be afforded protection from physical damage. (C) Interconnecting Leads. Interconnecting nonheating leads connecting portions of the heating system shall be 427.12 Thermal Protection. External surfaces of pipeline permitted to be covered by thermal insulation in the same and vessel heating equipment that operate at temperatures manner as the heaters. 70-296 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 427—FIXED ELECTRIC HEATING EQUIPMENT FOR PIPELINES AND VESSELS 427,37 427.19 Electrical Connections. 427.27 Voltage Limitations. Unless protected by ground- (A) Nonheating Interconnections. Nonheating intercon- fault circuit-interrupter protection for personnel, the sec- ondary winding of the isolation transformer connected to nections, where required under thermal insulation, shall be the pipeline or vessel being heated shall not have an output made with insulated connectors identified as suitable for voltage greater than 30 volts ac. this use. Where ground-fault circuit-interrupter protection for (B) Circuit Connections. Splices and terminations outside personnel is provided, the voltage shall be permitted to be the thermal insulation shall be installed in a box or fitting in greater than 30 but not more than 80 volts, accordance with 1 10.14 and 300.15. Exception: ht industrial establishments, the isolation transformer connected to the pipeline or vessel being 427.20 Marking. Each factory-assembled heating unit heated .shall be permitted to have an output voltage not shall be legibly marked within 75 mm (3 in.) of each end of greater than 132 volts ac to ground where all of the follow- the nonheating leads with the permanent identification sym- ing conditions apple: bol, catalog number, and ratings in volts and watts or in volts and amperes. (1) Conditions of'maintenance and supervision ensure that only qualified persons service the installed systems. 427.22 Equipment Protection. Ground-fault protection of (2) Ground fault protection of equipment is provided. equipment shall be provided for electric heat tracing and (3) The pipeline or vessel being berried is completely en- heating panels. This requirement shall not apply in indus- closed in a grounded metal enclosure. trial establishments where there is alarm indication of (4) The transformer secondary connections to the pipeline ground faults and the following conditions apply: or vessel being heated are completely enclosed in a (1) Conditions of maintenance and supervision ensure that grounded metal mesh or metal enclosure. only qualified persons service the installed systems. (2) Continued circuit operation is necessary for safe opera- 427.28 Induced Currents. All current-carrying cornpo- tion of equipment or processes. nents shall be installed in accordance with 300.20. 427.23 Grounded Conductive Covering. Electric heating 427.29 Grounding. The pipeline, vessel, or bath, that is equipment shall be listed and have a grounded conductive being heated and operating at a voltage greater than 30 but covering in accordance with 427.23(A)or(B).The conduc- not more than 80 shall be grounded at designated points. tive covering shall provide an effective ground path for equipment protection. 427.30 Secondary Conductor Sizing.The ampacity of the (A) Heating Wires or Cables. Heating wires or cables conductors connected to the secondary of the transformer shall have a grounded conductive covering that surrounds shall be at least 100 percent of the total load of the heater. the heating element and bus wires, if any, and their electri- cal insulation. V. Induction Heating (B) Heating Panels. Heating panels shall have a grounded 427.35 Scope. This part covers the installation of line fre- conductive covering over the heating element and its elec- quency induction heating equipment and accessories for trical insulation on the side opposite the side attached to the pipelines and vessels, surface to be heated. FPN: See Article 665 for other applications. IV. Impedance Heating 427.36 Personnel Protection. Induction coils that operate 427.25 Personnel Protection. All accessible external sur- or may operate at a voltage greater than 30 volts ac shall be faces of the pipeline, vessel, or both, being heated shall be enclosed in a nonmetallic or split metallic enclosure, iso- physically guarded, isolated, or thermally insulated (with a lated, or made inaccessible by location to protect personnel weatherproof jacket for outside installations) to protect in the area. against contact by personnel in the area. 427.37 Induced Current. Induction coils shall be pre- 427.26 Isolation Transformer. A dual-winding trans- vented from inducing circulating currents in surrounding former with a grounded shield between the primary and metallic equipment, supports, or structures by shielding, secondary windings shall be used to isolate the distribution isolation, or insulation of the current paths. Stray current system from the heating system. paths shall be bonded to prevent arcing. 2008 Edilion NATIONAL ELECTRICAL CODE 70--297 427.45 ARTICLE 430—MOTORS,MOTOR CIRCUITS,AND CONTROLI-ERS VI. Skin-Effect Heating (B) Temperature Control Without "Off" Position. Tem- perature controlled switching devices that do not have an 427.45 Conductor Ampacity.The ampacity of the electri- "off" position shall not be required to open all ungrounded cally insulated conductor inside the ferromagnetic envelope conductors and shall not be permitted to serve as the dis- shall be permitted to exceed the values given in Article 310, connecting means. provided it is identified as suitable for this use. (C) Remote Temperature Controller. Remote controlled 427.46 Pull Boxes. Pull boxes for pulling the electrically temperature-actuated devices shall not be required to meet insulated conductor in the ferromagnetic envelope shall be the requirements of 427.56(A) and(B). These devices shall permitted to be buried under the thermal insulation, pro- not be permitted to serve as the disconnecting means. vided their locations are indicated by permanent markings on the insulation jacket surface and on drawings. For out- (D) Combined Switching Devices. Switching devices door installations, pull boxes shall be of watertight con- consisting of combined temperature-actuated devices and struction. manually controlled switches that serve both as the control- lers and the disconnecting means shall comply with all the 427.47 Single Conductor in Enclosure.The provisions of following conditions: 300.20 shall not apply to the installation of a single con- (1) Open all ungrounded conductors when manually placed ductor in a ferromagnetic envelope (metal enclosure). in the "off' position 427.48 Grounding. The ferromagnetic envelope shall be (2) Be designed so that the circuit cannot be energized automatically if the device has been manually placed in grounded at both ends, and, in addition, it shall be permit- the "off' position ted to be grounded at intermediate points as required by its design. The ferromagnetic envelope shall be bonded at all (3) Be capable of being locked in the open position joints to ensure electrical continuity. 427.57 Overcurrent Protection. Heating equipment shall The provisions of 250.30 shall not apply to the instal- lation of skin-effect heating systems. be considered as protected against overcurrent where sup- g `y` plied by a branch circuit as specified in 210.3 and 210.23. FPN: See Article 250 for grounding methods. VII. Control and Protection 427.55 Disconnecting Means. ARTICLE 430 Motors, Motor Circuits, and Controllers (A) Switch or Circuit Breaker. Means shall be provided to simultaneously disconnect all fixed electric pipeline or vessel heating equipment from all ungrounded conductors. 1. General The branch-circuit switch or circuit breaker, where readily 430.1 Scope. This article covers motors, motor branch- accessible to the user of the equipment, shall be permitted circuit and feeder conductors and their protection, motor to serve as the disconnecting means. The disconnecting overload protection, motor control circuits, motor control- means shall be of the indicating type and shall be provided lers, and motor control centers. with a positive lockout in the "off' position. FPN No. 1: Installation requirements for motor control (B) Cord-and-Plug-Connected Equipment. The factory- centers are covered in 110.26(F). Air-conditioning and re- installed attachment plug of cord-and-plug-connected frigerating equipment are covered in Article 440. equipment rated 20 amperes or less and 150 volts or less to FPN No. 2: Figure 430.1 is for information only. ground shall be permitted to be the disconnecting means. 430.2 Definitions. 427.56 Controls. Adjustable Speed Drive.A combination of the power con- (A) Temperature Control with "Off" Position. Tem- verter, motor, and motor-mounted auxiliary devices such as perature-controlled switching devices that indicate an "off" encoders, tachometers, thermal switches and detectors, air position and that interrupt line current shall open all un- blowers, heaters, and vibration sensors. grounded conductors when the control device is in this "off"position.These devices shall not be permitted to serve Adjustable-Speed Drive System. An interconnected com- as the disconnecting means unless capable of being locked bination of equipment that provides a means of adjusting in the open position. the speed of a mechanical load coupled to a motor.A drive 70-298 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 43U—MOTORS. MOTOR CIRCUITS,AND CONTROLLERS 430.6 General,430.1 through 430.18 Part I actuator motor and other components Such as controllers, Motor Circuit Conductors,430.21 through 430.29 Part II torque switches, limit switches, and overload protection. Motor and Branch-Circuit Overload Protection,430.31 Part III through 430.44 FPN: VAMs typically have short-time duty and 'hi h Motor Branch-Circuit Short-Circuit and Ground-Fault Part IV �` g " Protection,430.51 through 430.58 torque characteristics. Motor Feeder Short-Circuit and Ground-Fault Protection, Part V 430.61 through 430.63 430.4 Part-Winding Motors. A part-winding start induc- Motor Control Circuits.430.71 through 430.74 Part A Motor Controllers,430.61 through 430.90 Part vu tion or synchronous motor is one that is arranged for start- Motor Control Centers,430.92 through 430.98 Part Vlll ing by first energizing part of its primary (armature) wind- Disconnecting Means,430,101 through 430.113 Part IX Adjustable Speed Drive Systems,430.120 through 430.128 Part X ing and, subsequently, energizing the remainder of this Over 600 Volts,Nominal,430.221 through 430.227 Part XI winding in one or more steps.A standard part-winding start Protection of Live Parts--All Voltages,430.231 Part XII b induction motor is arranged so that one-half of its primary through 430.233 Grounding All Voltages,430.241 through 430.245 Part XIII winding can be energized initially, and, subsequently, the Tables.Tables 430.247 through 430.251(B) Part XIV remaining halt can be energized, both halves then carrying To Supply Part Il equal current. A hermetic refrigerant compressor motor 430.24, shall not be considered a standard part-winding start induc- Motor leader 430.25,430.26 tion motor. Motor feeder Where separate overload devices are used with a stan- short-circuit and dard part-winding start induction motor, each half of the ground-fault protection Par[V motor winding shall be individually protected in accor- dance with 430.32 and 430.37 with a trip current one-half Motor branch-circuit specified. short-circuit and that s p ground-fault protection Part IV Each motor-winding connection shall have branch- Motor circuit conductor Part It circuit short-circuit and ground-fault protection rated at not Motor controller Part VII more than one-half that specified by 430.52. Motor control circuits Part VI Exception: A short-circuit and ground fault protective de- Motor overload protection Par[Ill vice shall be permitted for both windings if the device will Motor Part I allow the motor to start. Where time-delay (dual-element) Thermal protection 0 Par[III fuses are used, then shall be permitted to have a rating not Secondary controller Part 11 exceeding 150 percent of the motor full-load current. Secondary conductors 430.23 Secondary resistor Part II 430.5 Other Articles. Motors and controllers shall also 430.23 and Article 470 comply with the applicable provisions of Table 430.5. Figure 430.1 Article 430 Contents. 430.6 Ampacity and Motor Rating Determination. The system typically consists of an adjustable speed drive and size of conductors supplying equipment covered by Article auxiliary electrical apparatus. 430 shall be selected from the allowable ampacity tables in accordance with 310.15(B) or shall be calculated in accor- Controller. For the purpose of this article, a controller is dance with 310.15(C). Where flexible cord is used, the size any switch or device that is normally used to start and stop of the conductor shall be selected in accordance with 400.5. a motor by making and breaking the motor circuit current. The required ampacity and motor ratings shall be deter- Motor Control Circuit. The circuit of a control apparatus mined as specified in 430.6(A), (B), and (C), or system that carries the electric signals directing the per- formance of the controller but does not carry the main (A) General Motor Applications. For general motor ap- plications, current ratings shall be determined based on power current. (A)(1) and (A)(2). System Isolation Equipment. A redundantly monitored, remotely operated contactor-isolating system, packaged to (1) Table Values. Other than for motors built for low provide the disconnection isolation function, capable of speeds(less than 1200 RPM)or high torques,and for multi- provide operation from multiple remote locations by speed motors, the values given in Table 430.247, Table means of lockout switches, each having the capability of 430.245,Table 430.249, and Table 430.250 shall be used to being padlocked in the "ofd' (open) position. determine the ampacity of conductors or ampere ratings of switches, branch-circuit short-circuit and ground-fault pro- Valve Actuator Motor (VAM) Assemblies. A manufac- tection, instead of the actual current rating marked on the tured assembly, used to operate a valve, consisting of an motor nameplate. Where a motor is marked in amperes, but 2008 Edition NATIONAL ELECTRICAL CODE 70-299 430.7 ARTICLE 430—MOTORS,MOTOR CIRCUITS,AND CONTROLI FRS Table 430.5 Other Articles tection. This marking oil the equipment nameplate shall not he less than the current marked on the fan or blower motor Equipment/Occupancy Article Section nameplate. Air-conditioning and 440 Exception No. 3: For a listed motor-operated appliance refrigerating equipment that is marked with both motor horsepower and full-loud Capacitors 460.8,460.9 current, the motor full-load current marked on the name- Commercial garages; aircraft 511, 513, plate of the appliance shall be used instead of the horse- hangars; motor fuel 514, 515, power rating on the appliance nameplate to determine the dispensing facilities; bulk 516, and storage plants; spray 517 Part IV ampacity or rating of the disconnecting means, the branch- application, dipping, and circuit conductors, the controller, the branch-circuit short- coating processes: and circuit and ground fault protection, and any separate over- inhalation anesthetizing load protection. locations Cranes and hoists 610 (2) Nameplate Values. Separate motor overload protection Electrically driven or 675 shall be based on the motor nameplate current rating. controlled irrigation machines Elevators, dumbwaiters. 620 (B) Torque Motors. For torque motors, the rated current escalators, moving walks, shall be locked-rotor current, and this nameplate current wheelchair lifts, and shall be used to determine the ampacity of the branch- stairway chair lifts circuit conductors covered in 430.22 and 430.24, the am- Fire pumps 695 pere rating of the motor overload protection, and the am- Hazardous (classified) 500-503 pere rating of motor branch-circuit short-circuit and locations and 505 round-fault protection in accordance with 430.52(B). Industrial machinery 670 g p Motion picture projectors 540.11 and FPN: For motor controllers and disconnecting means, see Motion picture and television 530 540.20 430.83(D) and 430.110. studios and similar locations (C) Alternating-Current Adjustable Voltage Motors. Resistors and reactors 470 For motors used in alternating-current, adjustable voltage, Theaters, audience areas of 520.48 variable torque drive systems, the ampacity of conductors, motion picture and or ampere ratings of switches, branch-circuit short-circuit television studios, and and ground-fault protection, and so forth, shalt be based on similar locations the maximum operating current marked on the motor or Transformers and transformer 450 vaults control nameplate, or both. If the maximum operating cur- rent does not appear on the nameplate, the ampacity deter- mination shall be based on 150 percent of the values given not horsepower, the horsepower rating shall be assumed to in Table 430.249 and Table 430.250. be that corresponding to the value given in Table 430.247, Table 430.248, Table 430.249, and Table 430.250, interpo- 430.7 Marking on Motors and Multimotor Equipment. lated if necessary. Motors built for low speeds (less than 1200 RPM) or high torques may have higher full-load cur- (A) Usual Motor Applications. A motor shall be marked rents, and multispeed motors will have full-load current with the following information: varying with speed, in which case the nameplate current (1) Manufacturer's name. ratings shall be used. (2) Rated volts and full-load current. For a multispeed Exception No. 1: Multispeed motors shall be in actor- motor, full-load current for each speed, except shaded-pole and permanent-split capacitor motors dance with 430.22(A) and 430.52. where amperes are required only for maximum speed. Exception No. 2: For equipment that employs a shaded- (3) Rated frequency and number of phases if an ac motor. pole or permanent-split capacitor-type fan or blower motor (4) Rated full-load speed. that is marked with the motor type, the full load current for such motor marked on the nameplate of the equipment in (5) Rated temperature rise or the insulation system class which the fan or blower motor is employed shall be used and raked ambient temperature. instead of the horsepower rating to determine the ampacity (6) Time rating. The time rating shall be 5, 15, 30, or 60 or rating of the disconnecting means, the branch-circuit minutes, or continuous. conductors, the controller, the branch-circuit short-circuit (7) Rated horsepower if '/8 hp or more. For a multispeed and ground fault protection, and the separate overload pro- motor 1/k hp or more,rated horsepower for each speed, 70_30 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 430-MOTORS,MOTOR CIRCUITS,AND CONTROLLERS 430.7 except shaded-pole and permanent-split capacitor mo- Table 430.7(B) Locked-Rotor Indicating Code Letters tors 1/8 hp or more where rated horsepower is required only for maximum speed. Motors of arc welders are Kilovolt-Amperes per Horsepower not required to be marked with the horsepower rating, Code Letter with Locked Rotor (8) Code letter or locked-rotor amperes if an alternating- A 0-3.14 current motor rated 1/2 hp or more. On polyphase B 3.15-3.54 wound-rotor motors, the code letter shall be omitted. C 3.55-3.99 FPN: See 430.7(B). D 4.0--4.49 (9) Design letter for design B, C, or D motors. E 4.5-4.99 F 5.0-5.59 FPN: Motor design letter definitions are found in G 5.6-6.29 ANSI/NEMA MC 1-1993,Motors and Generators, Part 1, H 6.3-7.09 Definitions, and in IEEE 100-1996,Standard Dictionary of Electrical and Electronic- Tenns. 7 7.1--7.99 (10) Secondary volts and full-load current if a wound-rotor K 8.0-8.99 induction motor. L 9.0-9.99 {I 1} Field current and voltage for do excited synchronous M 10.0-11.19 motors. N 11.2-12.49 (12) Winding - straight shunt, stabilized shunt, com- P 12,5-13.99 pound, or series, if a do motor. Fractional horsepower R 14.0-15.99 S 16.0-17.99 do motors 175 mm (7 in.) or less in diameter shall not be required to be marked. T 18.t1-.19,99 (13) A motor provided with a thermal protector complying U 20.0'22.39 with 430.32(A)(2) or (13)(2) shall be marked "Ther- V 22.4 and up mally Protected." Thermally protected motors rated 100 watts or less and complying with 430.32(B)(2) shall be marked with a code letter corresponding to the shall be permitted to use the abbreviated marking locked-rotor kilovolt-ampere (kVA) per horsepower for "T.P," the wye connection. (14) A motor complying with 430.32(B)(4) shall be (3) Dual-Voltage Motors. Dual-voltage motors that have a marked "Impedance Protected." Impedance-protected different locked-rotor kilovolt-ampere (kVA) per horse- motors rated 100 watts or less and complying with power on the two voltages shall be marked with the code 430.32(B)(4) shall be permitted to use the abbreviated letter for the voltage giving the highest locked-rotor marking "Z.P." kilovolt-ampere (kVA) per horsepower. (15) Motors equipped with electrically powered condensa- (4) 50160 Hz Motors. Motors with 50- and 60-Hz ratings tion prevention heaters shall be marked with the rated heater voltage, number of phases, and the rated power shall be marked with a code letter designating the locked- in watts. rotor kilovolt-ampere (kVA) per horsepower on 60 Hz. (B) Locked-Rotor Indicating Code Letters. Code letters (5) Part Winding Motors. Part-winding start motors shall be marked with a code letter designating the locked-rotor marked on motor nameplates to show motor input with kilovolt-ampere (kVA) per horsepower that is based on the locked rotor shall be in accordance with Table 430.7(B}. The code letter indicating motor input with locked rotor lacked-rotor current for the full winding of the motor. shall be in an individual block on the nameplate, properly (C) Torque Motors.Torque motors are rated for operation designated. at standstill and shall be marked in accordance with (1) Multispeed Motors. Multispeed motors shall be 430.7(A), except that locked-rotor torque shall replace marked with the code letter designating the locked-rotor horsepower. kilovolt-ampere (kVA) per horsepower for the highest (D) Multimotor and Combination-Load Equipment. speed at which the motor can be started. Exception: Constant horsepower multispeed motors shall (1) Factory-Wired. Multimotor and combination-load equipment shall be provided with a visible nameplate he marked with th the coda letter giving the Iri{'hest lurked- marked with the manufacturer's name, the rating in volts, rotor kilovolt-aittpere (kVA)per horsepower. marked number of phases, minimum supply circuit con- (2) Single-Speed Motors. Single-speed motors starting ductor ampacity, and the maximum ampere rating of the on wye connection and running on delta connections circuit short-circuit and ground-fault protective device.The 2008 Edition NATIONAL ELECTRICAL CODE 70-301 430.8 ARTICLE 430—MOTORS,MOTOR CIRCUITS,AND CONTROLLERS conductor ampacity shall be calculated in accordance with (B) Conductors. Motor controllers and terminals of con- 430.24 and counting all of the motors and other loads that trol circuit devices shall be connected with copper conduc- will be operated at the same time. The short-circuit and tors unless identified for use with a different conductor. ground-fault protective device rating shall not exceed the value calculated in accordance with 430.53. Multimotor (C) Torque Requirements. Control circuit devices with equipment for use on two or more circuits shall be marked screw-type pressure terminals used with 14 AWG or smaller with the preceding information for each circuit. copper conductors shall be torqued to a minimum of 0.8 N•m (7 lb-in.) unless identified for a different torque value. (2) Not Factory-Wired. Where the equipment is not factory-wired and the individual nameplates of motors and 430.10 Wiring Space in Enclosures. other loads are visible after assembly of the equipment, the individual nameplates shall be permitted to serve as the (A) General.Enclosures for motor controllers and discon- required marking. necting means shall not be used as junction boxes,auxiliary gutters, or raceways for conductors feeding through or tap- 430.8 Marking on Controllers. A controller shall be ping off to the other apparatus unless designs are employed marked with the manufacturer's name or identification, the that provide adequate space for this purpose. voltage, the current or horsepower rating, the short-circuit current rating, and such other necessary data to properly FPN: See 312.8 for switch and overcurrent-device enclosures. indicate the applications for which it is suitable. (B) Wire-Bending Space in Enclosures. Minimum wire- Exception No. 1: The short-circuit current rating is not bending space within the enclosures for motor controllers required for controllers applied in accordance with shall be in accordance with Table 430.10(B) where mea- 430.81(A) or (B). sured in a straight line from the end of the lug or wire Exception No. 2: The short-circuit rating is not required to connector (in the direction the wire leaves the terminal) to be marked on the controller when the short-circuit current the wall or barrier. Where alternate wire termination means rating of the controller is marked elsewhere on the are substituted for that supplied by the manufacturer of the assembly. controller, they shall be of a type identified by the manu- Exception No. 3: The short-circuit rating is not required to facturer for use with the controller and shall not reduce the be marked on the controller when the assembly into which minimum wire-bending space. it is installed has a marked short-circuit current rating. 430.11 Protection Against Liquids. Suitable guards or en- Exception No. 4: Short-circuit ratings are not required for closures shall be provided to protect exposed current-carrying controllers rated less than 2 hp at 300 V or less and listed parts of motors and the insulation of motor leads where in- exclusively for general-purpose branch circuits. A controller that includes motor overload protection Table 430.10(B) Minimum Wire-Bending Space at the suitable for group motor application shall be marked with Terminals of Enclosed Motor Controllers the motor overload protection and the maximum branch- circuit short-circuit and ground-fault protection for such Size of Fires per Terminal" applications. Wire 1 2 Combination controllers that employ adjustable instan- (AWG or taneous trip circuit breakers shall be clearly marked to in- kcmil) mm in. arm in. dicate the ampere settings of the adjustable trip element. 14-10 Not specified — -- Where a controller is built in as an integral part of a 9_6 38 11/2 motor or of a motor-generator set, individual marking of 4-3 50 2 --the controller shall not be required if the necessary data are 2 65 21/2 —on the nameplate. For controllers that are an integral part of 1 75 3 equipment approved as a unit, the above marking shall be 110 125 5 125 5 210 150 6 150 6 permitted on the equipment nameplate. 3/0-4/0 175 7 175 7 FPN: See l 10.10 for information on circuit impedance and 250 200 8 200 8 300 250 10 250 10 other characteristics. 350-500 300 12 300 12 600-700 350 14 400 16 430.9 Terminals. 750-900 450 18 475 19 (A) Markings. Terminals of motors and controllers shall •Where provision for three or more wires per terminal exists, the be suitably marked or colored where necessary to indicate minimum wire-bending space shall be in accordance with the require- the proper connections. ments of Article 312. 70-.302 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 430—MOTORS. MOTOR CIRCUITS,AND CONTROLLERS 430.12 stalled directly under equipment, or in other locations where Table 430.12(B) Continued dripping or spraying oil, water, or other liquid may occur, unless the motor is designed for the existing conditions. Direct-Current Motors 430.12 Motor Terminal Housings. Maximum Full-Load Terminal Box (A) Material. Where motors are provided with terminal Current for Minimum Usable Volume housings, the housings shall be of metal and of substantial Motors with Dimensions Minimum construction, Maximum or 6 Leads Exception: In other than hazardous (classified) locations, (Amperes) mm in, em' in.' substantial, nonmetallic, norrbuming housings shall be per- 68 65 2.5 425 26 mitted, provided an intental grounding means between the 105 84 3,3 900 55 motor frame and the equipment grounding connection is 165 100 4.0 1,640 100 incorporated within the housing. 240 125 5.0 2,950 180 375 150 6.0 5,410 330 (B) Dimensions and Space — Wire-to-Wire Connec- 600 175 7.0 9,840 600 tions. Where these terminal housings enclose wire-to-wire 900 200 8.0 18,040 1,100 connections, they shall have minimum dimensions and us- Note: Auxiliary leads for such items as brakes, thermostats, space able volumes in accordance with Table 430.12(B), heaters, and exciting fields shall be permitted io be neglected if their current-carrying area does not exceed 25 percent of the current- (C) Dimensions and Space -- Fixed Terminal Connec- carrying area of the machine power leads. tions.Where these terminal housings enclose rigidly mounted 'For motors rated I hp and smaller and with the terminal housing par- motor terminals, the terminal housing shall be of sufficient tially or wholly integral with the frame or end shield,the volume of the terminal housing shall not be less than 18.0 em' (1.1 in.') per wire-to- L,to provide minimum terminal spacings and usable vol- wire connection.The minimum cover opening dimension is not specified. umes in accordance with Table 430.12(C)(1) and Table "For motors rated 1'h,2,and 3 hp and with the terminal housing partially 430,12(C)(2). or wholly integral with the frame or end shield,the volume of the termi- nal housing shall not be less than 23,0 cm' (1.4 in.) per win-to-wire Table 430.12(B) Terminal Housings—Wire-to-Wire connection.The minimum cover opening dimension is not specified. Connections Table 430.12(C)(1) Terminal Spacings—Fixed Terminals Motors 275 mm (tl in.) in Diameter or Less Cover Opening Usable Volume Minimum Spacing Minimum Dimension Minimum Between Line Horsepower mm in. cm' in.' Terminals and Between Line Other Uninsulated and smaller-' 41 15/8 170 10.5 Nominal Terminals Metal Parts l'/, 2, and 3'' 45 1'14 275 16.8 Volts mm in, mm in. 5 and 7'/a 50 2 365 22.4 10 and 15 65 21/ 595 36.4 240 or less 6 114 6 '/4 Motors Over 275 mm (11 in.) in Diameter— Over 250-600 10 31a 10 1/8 Alternating-Current Motors Maximum Terminal Table 430.12(0)(2) Usable Volumes—Fixed Terminals Full Load Box Cover Typical Current for Opening Usable Maximum Minimum Usable Volume per 3-Phase Minimum Volume Horsepower Power-Supply Power-Supply Conductor Motors with Dimension Minimum 3-Phase Conductor Size Maximum or (AWG) cm' in.' 12 Leads 230 460 (Amperes) mm in. cm' in.' Volt Volt 14 16 1 12 and 10 20 1114 45 65 2.5 595 36.4 15 30 8 and 6 37 2'/4 70 84 3.3 1,265 77 25 50 110 100 4.0 2,295 140 40 75 (D) Large Wire or Factory Connections. For motors with 160 125 5.0 4,135 252 60 125 larger ratings.greater number of leads,or larger wire sizes,or 250 150 6.0 7,380 450 100 200 g 400 175 7.0 13,775 840 150 300 where motors are installed as a part of factory-wired equip- 600 200 8.0 25,255 1540 250 50O ment, without additional connection being required at 2005 Edition NATIONAL ELECTRICAL CODE 70-303 430.13 ARTICLE 430—MOTORS,MOTOR CIRCUITS.AND CONTROLLERS the motor terminal housing during equipment installation, the 430.17 Highest Rated or Smallest Rated Motor. In de- terminal housing shall be of ample size to make connections, termining compliance with 430.24, 430.53(B), and but the foregoing provisions for the volumes of terminal hous- 430.53(C), the highest rated or smallest rated motor shall ings shall not be considered applicable, be based on the rated full-load current as selected from Table 430.247, Table 430.248, Table 430.249, and Table (E) Equipment Grounding Connections.A means for at- 430.250. tachment of an equipment grounding conductor termination in accordance with 250.8 shall be provided at motor termi- 430.18 Nominal Voltage of Rectifier Systems.The nomi- nal housings for wire-to-wire connections or fixed terminal nal value of the ac voltage being rectified shall be used to connections. The means for such connections shall be per- determine the voltage of a rectifier derived system. mitted to be located either inside or outside the motor ter- minal housing. Exception: The nominal do voltage of the rectifier shall be Exception: Where a motor is installed as a part of factory- used if it exceeds the peak value of the ac voltage being wired equipment that is required to be grounded and with- rectified out additional connection being required at the motor ter- minal housing during equipment installation, a separate II. Motor Circuit Conductors means for motor grounding at the motor terminal housing shall not be required. 430.21 General. Part II specifies ampacities of conductors that are capable of carrying the motor current without over- 430.13 Bushing. Where wires pass through an opening in heating under the conditions specified. an enclosure, conduit box, or barrier, a bushing shall be The provisions of Part II shall not apply to motor cir- used to protect the conductors from the edges of openings cuits rated over 600 volts, nominal. having sharp edges. The bushing shall have smooth, well- The provisions of Articles 250, 300, and 310 shall not rounded surfaces where it may be in contact with the con- apply to conductors that form an integral part of equipment, ductors. If used where oils, greases, or other contaminants such as motors, motor controllers, motor control centers, or may be present, the bushing shall be made of material not other factory-assembled control equipment. deleteriously affected. FPN No. I: See 300.1(B) and 310.1 for similar FPN: For conductors exposed to deteriorating agents, see requirements. 310.9. FPN No. 2: See 110.14(C) and 430.9($) for equipment 430.14 Location of Motors. device terminal requirements. FPN No. 3: For over 600 volts, nominal, see Part XI. (A) Ventilation and Maintenance. Motors shall be lo- cated so that adequate ventilation is provided and so that 430.22 Single Motor. maintenance, such as lubrication of bearings and replacing of brushes, can be readily accomplished. (A) General. Conductors that supply a single motor used Exception: Ventilation shall not be required for submers- to a continuous duty application shall have an ampacity of not less than 125 percent of the motor's full-load current ible types of motors. rating as determined by 430.6(A)(1). (B) Open Motors. Open motors that have commutators or Exception: For do motors operating from a rectified collector rings shall be located or protected so that sparks single-phase power supply, the conductors between the field cannot reach adjacent combustible material. wiring terminals of the rectifier and the motor shall have an Exception: Installation of these motors on wooden floors ampacity of not less than the following percent of the motor or supports shall be permitted full-load current rating: (a) Where a rectifier bridge of the single-phase half- 430.16 Exposure to Dust Accumulations. In locations wave type is used, 190 percent. where dust or flying material collects on or in motors in (b) Where a rectifier bridge of the single-phase full- such quantities as to seriously interfere with the ventilation wave type is used, 150 percent. or cooling of motors and thereby cause dangerous tempera- tures,suitable types of enclosed motors that do not overheat (B) Multispeed Motor. For a multispeed motor, the selec- under the prevailing conditions shall be used, tion of branch-circuit conductors on the line side of the FPN: Especially severe conditions may require the use of en- controller shall be based on the highest of the full-load closed pipe-ventilated motors, or enclosure in separate dust- current ratings shown on the motor nameplate. The selec- tight rooms,properly ventilated from a source of clean air. tion of branch-circuit conductors between the controller 70-304 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 430—MOTORS,MOTOR CIRCUITS,AND CONTROLLERS 430.24 and the motor shall be based on the current rating of the 430.23 Wound-Rotor Secondary. winding(s) that the conductors energize. (A) Continuous Duty. For continuous duty,the conductors (C) Wye-Start, Delta-Run Motor. For a wye-start, delta- connecting the secondary of a wound-rotor ac motor to its run connected motor, the selection of branch-circuit con- controller shall have an ampacity not less than 125 percent ductors on the line side of the controller shall be based on of the full-load secondary current of the motor. the motor full-load current. The selection of conductors (g) Other Than Continuous Duty. For other than con- between the controller and the motor shall be based on tinuous duty, these conductors shall have an ampacity, in 58 percent of the motor full-load current. percent of full-load secondary current, not less than that (D) Part-Winding Motor. For a part-winding connected specified in Table 430.22(E). motor,the selection of branch-circuit conductors on the line (C) Resistor Separate from Controller. Where the sec- side of the controller shall be based on the motor full-load ondary resistor is separate from the controller, the ampacity current. The selection of conductors between the controller of the conductors between controller and resistor shall not and the motor shall be based on 50 percent of the motor be less than that shown in Table 430.23(C). full-load current. Table 430.23(C) Secondary Conductor (E) Other Than Continuous Duty. Conductors for a mo- tor used in a short-time, intermittent, periodic, or varying Ampacity of Conductor in duty application shall have an ampacity of not less than the Percent of Full-Load percentage of the motor nameplate current rating shown in Resistor Duty Classification Secondary Current Table 430.22(E), unless the authority having jurisdiction Light starting duty 35 grants special permission for conductors of lower ampacity. Heavy starting duty 45 Extra-heavy starting duty 55 Table 430.22(E) Duty-Cycle Service Light intermittent duty 65 Medium intermittent duty 75 Nameplate Current Rating Percentages Heavy intermittent duty 85 30- & 60- Contin- Continuous duty 110 5-Minute 15-Minute Minute uous Classification of Rated Rated Rated stated 430.24 Several Motors or a Motor(s) and Other Service Motor Motor Motor Motor Load(s). Conductors supplying several motors, or a mo- Short-time duty 110 120 150 — tor(s) and other load(s), shall have an ampacity not less operating valves, than 125 percent of the full-load current rating of the high- raising or lowering est rated motor plus the sum of the full-load current ratings rolls,etc. p of all the other motors in the group, as determined by Intermittent duty 85 85 90 140 430.6(A), plus the ampacity required for the other loads. freight and passenger elevators, FPN: See Annex D, Example No. D8. tool heads,pumps, drawbridges, Exception No. 1: Where one or more of the motors of the turntables,etc. (for are welders,see group are used for short-time, intermittent, periodic, or 630.11) varying duty, the ampere rating of such motors to be used in the summation shall be determined in accordance with Periodic duty rolls, 85 90 95 140 ore- and 430.22(E). e highest For th hest rated motor, the greater of ei- coal-handling ther the ampere rating from 430.22(E) or the largest con- machines,etc. tinuous duty motor full-loud current multiplied by 1.25 Varying duty 110 120 150 200 shall be used in the summation. Exception No. 2: T1ne ampacity of conductors supplying Note: Any motor application shall he considered as continuous duty motor-operated fixed electric space-heating equipment unless the nature of the apparatus it drives is such that the motor will not operate continuously with load under any condition of use. shall comply with 424.3($), Exception No. 3: Where the circuitry is interlocked so as to (F) Separate Terminal Enclosure. The conductors be- prevent operation of selected motors or other loads at the tween a stationary motor rated I hp or less and the separate same time, the conductor ampacity,shall be permitted to be terminal enclosure permitted in 430.245(B)shall be permitted based on the summation of the currents of the motors and to be smaller than 14 AWG but not smaller than 18 AWG, other loads to be operated at the same time that results in provided they have an ampacity as specified in 430.22(A). the highest total current. 2(H)R Edition NATIONAL ELECTRICAL CODE 70-305 430.25 ARTICLE 430—MOTORS,MOTOR CIRCUITS,AND CONTROLLERS 430.25 Multimotor and Combination-Load Equipment. b. The tap conductors terminate with a single circuit The ampacity of the conductors supplying multimotor and breaker or a single set of fuses complying with(1)Part combination-toad equipment shall not be less than the mini- IV, where the load-side conductors are a branch circuit, mum circuit ampacity marked on the equipment in accor- or (2) Part V, where the load-side conductors are a dance with 430.7(D). Where the equipment is not factory- feeder wired and the individual nameplates are visible in c. The tap conductors are suitably protected from physi- accordance with 430.7(D)(2), the conductor ampacity shall cal damage and are installed in raceways. be determined in accordance with 430.24. d. The tap conductors are continuous from end-to-end 430.26 Feeder Demand Factor.Where reduced heating of and contain no splices. the conductors results from motors operating on duty-cycle, e. The tap conductors shall be 6 AWG copper or 4 AWG intermittently, or from all motors not operating at one time, aluminum or larger the authority having jurisdiction may grant permission for f. The tap conductors shall not penetrate walls,floors, or feeder conductors to have an ampacity less than specified in ceilings. 430.24, provided the conductors have sufficient ampacity g. The tap shall not be made less than 9.0 m (30 ft)from for the maximum load determined in accordance with the the floor sizes and number of motors supplied and the character of their loads and duties. 430.29 Constant Voltage Direct-Current Motors — FPN: Demand factors determined in the design of new fa- Power Resistors. Conductors connecting the motor con- cilities can often be validated against actual historical ex- troller to separately mounted power accelerating and dy- perience from similar installations. Refer to ANSIIIEEE namic braking resistors in the armature circuit shall have an Std. 141, IEEE Recommended Practice for Electric Power ampacity not less than the value calculated from Table Distribution for Industrial Plants, and ANSI/IEEE Std. 241,Recommended Practice for Electric Power Systems in 430.29 using motor full-load current. If an armature shunt Commercial Buildings, for information on the calculation resistor is used, the power accelerating resistor conductor of loads and demand factor. ampacity shall be calculated using the total of motor full- load current and armature shunt resistor current. 430.27 Capacitors with Motors. Where capacitors are in- Armature shunt resistor conductors shall have an am- stalled in motor circuits, conductors shall comply with pacity of not less than that calculated from Table 430.29 460.8 and 460.9. using rated shunt resistor current as full-load current. 430.28 Feeder Taps. Feeder tap conductors shall have an Table 430.29 Conductor Rating Factors for Power Resistors ampacity not less than that required by Part II, shall termi- nate in a branch-circuit protective device, and, in addition, shall meet one of the following requirements: Time in Seconds Conductor of or in (1) Be enclosed either by an enclosed controller or by a Percent of raceway, be not more than 3.0 m (10 ft) in length, and, On Off Full-Load Current for field installation, be protected by an overcurrent 5 75 35 device on the line side of the tap conductor, the rating 10 70 45 or setting of which shall not exceed 1000 percent of the 15 75 55 Lap conductor ampacity 15 45 65 (2) Have an ampacity of at least one-third that of the feeder 15 30 75 conductors, be suitably protected from physical damage 15 15 85 Continuous Duty ]10 or enclosed in a raceway, and be not more than 7.5 m (25 ft) in length (3) Have an ampacity not less than the feeder conductors Ill. Motor and Branch-Circuit Overload Protection Exception: Feeder taps over 7.5 m(25 ft)long. In high-bay 430.31 General. Part Ill specifies overload devices in- manufacturing buildings (over 11 m (35 ft) high at wallsJ, tended to protect motors, motor-control apparatus, and mo- where conditions of maintenance and supervision ensure for branch-circuit conductors against excessive heating due that only qualified persons service the systems, conductors to motor overloads and failure to start. tapped to a feeder shall be permitted to be not over 7.5 m • (25 ft) long horizontally and not over ,30.0 m (100 ft) in FPN: Sea the definition of Overload in Article 100. total length where all of the following conditions are met: These provisions shall not be interpreted as requiring a. The ampacity of the tap conductors is not less than overload protection where it might introduce additional or one-third that of the feeder conductors. increased hazards, as in the case of fire pumps. 70-306 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 430—MOTORS, MOTOR CIRCUITS,AND CONTROLLERS 430.32 FPN: For protection of fire pump supply conductors, see If the motor current-interrupting device is separate from 695.7. the motor and its control circuit is operated by a protective The provisions of Part III shall not apply to motor cir- device integral with the motor, it shall be arranged so that cuits rated over 600 volts, nominal. the opening of the control circuit will result in interruption of current to the motor. FPN No. 1: For over 600 volts, nominal, see Part XI. (3) Integral with Nlotor. A protective device integral with FPN No. 2: See Annex D. Example No. D8. a motor that will protect the motor against damage due to failure to start shall be permitted if the motor is part of an 430.32 Continuous-Duty Motors. approved assembly that does not normally subject the mo- (A) More Than 1 Horsepower. Each motor used in a con- for to overloads. tinuous duty application and rated more than I hp shall be (4) Larger Than 1500 Horsepower. For motors larger protected against overload by one of the means in than 1500 hp, a protective device having embedded tem- 430.32(A)(1) through (A)(4). perature detectors that cause current to the motor to be (1) Separate Overload Device. A separate overload de- interrupted when the motor attains a temperature rise vice that is responsive to motor current. This device shall greater than marked on the nameplate in an ambient tem- be selected to trip or shall be rated at no more than the perature of 40°C. following percent of the motor nameplate full-load current (B) One Horsepower or Less, Automatically Started. rating: Any motor of 1 hp or less that is started automatically shall Motors with a marked service 125% be protected against overload by one of the following factor 1.15 or greater means. Motors with a marked 125% temperature rise 40°C or (1) Separate Overload Device. By a separate overload less device following the requirements of 430.32(A)(1). All other motors 115�h For a multispeed motor, each winding connection shall be considered separately. Modification of this value shall be Modification of this value shall be permitted as provided in permitted as provided in 430.32(0). 430.32(C). For a multispeed motor, each winding connec- tion shall be considered separately. (2) Thermal Protector. A thermal protector integral with the motor, approved for use with the motor that it protects on Where a separate motor overload device is connected so the basis that it will prevent dangerous overheating of the that it does not carry the total current designated on the motor due to overload and failure to start. Where the motor motor nameplate, such as for wye-delta starting, the proper current-interrupting device is separate from the motor and its percentage of nameplate current applying to the selection or control circuit is operated by a protective device integral with setting of the overload device shall be clearly designated on the motor, it shall be arranged so that the opening of the the equipment, or the manufacturer's selection table shall control circuit results in interruption of current to the motor. take this into account. (3) Integral with Motor. A protective device integral with FPN: Where power factor correction capacitors are in- a motor that protects the motor against damage due to fail- stalled on the load side of the motor overload device, see ure to start shall be permitted (1) if the motor is part of an 460.9. approved assembly that does not subject the motor to over- loads,or(2)if the assembly is also equipped with other safety (2) Thermal Protector. A thermal protector integral with controls(such as the safety combustion controls on a domestic the motor, approved for use with the motor it protects on oil burner)that protect the motor against damage due to failure the basis that it will prevent dangerous overheating of the to start. Where the assembly has safety controls that protect motor due to overload and failure to start. The ultimate trip the motor, it shall be so indicated on the nameplate of the current of a thermally protected motor shall not exceed the assembly where it will be visible after installation. following percentage of motor full-load current given in Table 430.248, Table 430.249, and Table 430.250: (4) Impedance-Protected. If the impedance of the motor windings is sufficient to prevent overheating due to failure to start, the motor shall be permitted to be protected as Motor full-load current 9 amperes or less 170% specified in 430.32(D)(2)(a) for manually started motors if Motor full-load current from 9.1 to, and 156CIo the motor is part of an approved assembly in which the including, 20 amperes motor will limit itself so that it will not be dangerously Motor full-load current greater than 20 amperes 140% overheated. 2008 Edition NATIONAL ELECTRICAL CODE 70-307 430.33 ARTICLE 430 MOTORS,MOTOR CIRCUITS,AND CONTROLLERS FPN: Many ac motors of less than 1/2o hp, such as clock 430.22(E), shall be permitted to be protected against over- motors, series motors, and so north. and also some larger load by the branch-circuit short-circuit and ground-fault motors such as torque motors, come within this classi6ca- protective device, provided the protective device rating or tion. It does not include split-phase motors having auto- matic switches that disconnect the starting windings. setting does not exceed that specified in Table 430.52. Any motor application shall be considered to be for (C) Selection of Overload Device. Where the sensing el- continuous duty unless the nature of the apparatus it drives ement or setting or sizing of the overload device selected in is such that the motor cannot operate continuously with accordance with 430.32(A)(1) and 430.32(B)(1) is not suf- load under any condition of use. ficient to start the motor or to carry the load, higher size sensing elements or incremental settings or sizing shall be 430.35 Shunting During Starting Period. permitted to be used, provided the trip current of the over- load device does not exceed the following percentage of (A) Nonautomatically Started. For a nonautomatically motor nameplate full-load current rating: started motor, the overload protection shall be permitted to be shunted or cut out of the circuit during the starting pe- Motnrs with marked service factor 1.15 or 140% riod of the motor if the device by which the overload pro- greater tection is shunted or cut out cannot be left in the starting Motors with a marked temperature rise 40°C or 140% position and if fuses or inverse time circuit breakers rated less or set at not over 400 percent of the full-load current of the All other motors 130% motor are located in the circuit so as to be operative during the starting period of the motor. If not shunted during the starting period of the motor as provided in 430.35, the overload device shall have suff- (B) Automatically Started. The motor overload protec- cient time delay to permit the motor to start and accelerate tion shall not be shunted or cut out during the starting period if the motor is automatically started. its load. FPN: A Class 20 or Class 30 overload relay will provide a Exception: The motor overload protection shall be permit- longer motor acceleration time than a Class 10 or Class 20, ted to be shunted or cut out during the starting period on respectively. Use of a higher class overload relay may pre- an automatically started motor where the following apply: clude the need for selection of a higher trip current. (a) The motor starting period exceeds the time delay of (D) One Horsepower or Less, Nonautomatically available motor overload protective devices, and Started. (b) Listed means are provided to perform the following: (1) Permanently Installed. Overload protection shall be (1) Sense motor rotation and automatically prevent the shunting or cutout in the event that the motor fails to in accordance with 430.32(B)' start, and (2) Not Permanently Installed. (2) Limit the time of overload protection shunting or cutout to less than the locked rotor time rating of the protected (a) Within Sight from Controller. Overload protection motor, and shall be permitted to be furnished by the branch-circuit (3) provide for shutdown and manual restart if motor run- short-circuit and ground-fault protective device; such de- ning condition is not reached vice, however, shall not be larger than that specified in Part IV of Article 430. 430.36 Fuses — In Which Conductor. Where fuses are Exception: Any such motor shall be permitted on a nomi- used for motor overload protection, a fuse shall be inserted nal 120-volt branch circuit protected at not over 20 in each ungrounded conductor and also in the grounded amperes. conductor if the supply system is 3-wire, 3-phase ac with (b) Not Within Sight from Controller. Overload protec- one conductor grounded. tion shall be in accordance with 430.32(8). 430.37 Devices Other Than Fuses—In Which Conduc- (E) Wound-Rotor Secondaries.The secondary circuits of tor. Where devices other than fuses are used for motor wound-rotor ac motors, including conductors, controllers, overload protection, Table 430.37 shall govern the mini- resistors, and so forth, shall be permitted to be protected mum allowable number and location of overload units such against overload by the motor-overload device. as trip coils or relays. 430.33 Intermittent and Similar Duty. A motor used for 430.38 Number of Conductors Opened by Overload a condition of service that is inherently short-time,intermit- Device. Motor overload devices, other than fuses or ther- tent, periodic, or varying duty, as illustrated by Table mal protectors, shall simultaneously open a sufficient 70-308 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 430—MOTORS,MOTOR CIRCUITS,AND CONTROLLERS 430.44 Table 430.37 Overload Units circuit breaker 6v which they must be protected, the over- load devices shall he protected in accordance with this Number and marking. Location of Overload Units, FPN: For instantaneous trip circuit breakers or motor Such as THp short-circuit protectors, see 430.52. Kind of Motor Supply System Coils or Relays 430.42 Motors on General-Purpose Branch Circuits. 1-phase ac or do 2-wire, 1-phase ac l in either Overload protection for motors used on general-purpose or do ungrounded conductor branch circuits as permitted in Article 210 shall be provided I-phase ac or do 2-wire, I-phase ac I in ungrounded as specified in 430.42(A), (B), (C), or (D). or dc, one conductor conductor (A) Not over I Horsepower. One or more motors without grounded individual overload protection shall be permitted to be con- nected to a general-purpose branch circuit only where the or dc. grounded ungrounded 1-phase ac or do 3-wire, ac 1 in either installation complies with the limiting conditions specified neutral conductor conductor in 430.32(B) and 430.32(D) and 430.53(A)(1) and (A)(2). I-phase ac Any 3-phase 1 in ungrounded (B) Over 1 Horsepower. Motors of ratings larger than conductor specified in 430.53(A) shall be permitted to be connected to general-purpose branch circuits only where each motor is 2-phase ac 3-wire, 2-phase ac, 2, one in each protected by overload protection selected to protect the mo- ungrounded phase for as specified in 430.32. Both the controller and the motor 2-phase ac 3-wire, 2-phase ac, 2 in ungrounded overload device shall be approved for group installation one conductor conductors with the short-circuit and ground-fault protective device grounded selected in accordance with 430.53. 2-phase ac 4-wire, 2-phase ac, 2, one per phase in (C) Cord-and-Plug-Connected. Where a motor is con- grounded or ungrounded con- nected to a branch circuit by means of an attachment plug ungrounded ductors and receptacle and individual overload protection is omit- 2-phase ac Grounded neutral 2, one per phase in ted as provided in 430.42(A), the rating of the attachment or 5-wire, 2-phase any ungrounded plug and receptacle shall not exceed 15 amperes at 125 ac. ungrounded phase wire volts or 250 volts. Where individual overload protection is 3-phase ac Any 3-phase 3, one in each required as provided in 430.42(B) for a motor or motor- phase* operated appliance that is attached to the branch circuit through an attachment plug and receptacle, the overload *Exception: An overload unit in early phase shall not be regidred device shall be an integral part of the motor or of the where overload protection is provided by other approved meats. appliance, The rating of the attachment plug and receptacle number of ungrounded conductors to interrupt current shall determine the rating of the circuit to which the motor flow to the motor. may be connected, as provided in Article 210. 430.39 Motor Controller as Overload Protection. A mo- (D) Time Delay. The branch-circuit short-circuit and for controller shall also be permitted to serve as an overload ground-fault protective device protecting a circuit to which device if the number of overload units complies with Table a motor or motor-operated appliance is connected shall 430.37 and if these units are operative in both the starting have sufficient time delay to permit the motor to start and and running position in the case of a do motor, and in the accelerate its load. running position in the case of an ac motor. 430.43 Automatic Restarting. A motor overload device 430.40 Overload Relays. Overload relays and other de- that can restart a motor automatically after overload trip- vices for motor overload protection that are not capable of ping shall not be installed unless approved for use with the opening short circuits or ground faults shall be protected by motor it protects.A motor overload device that can restart a fuses or circuit breakers with ratings or settings in accor- motor automatically after overload tripping shall not be dance with 430.52 or by a motor short-circuit protector in installed if automatic restarting of the motor can result in accordance with 430.52. injury to persons. Exception: Where approved for group installation and 430.44 Orderly Shutdown. If immediate automatic shut- marked to indicate the maximum size of fitse or inverse tone down of a motor by a motor overload protective device(s) 2008 Edition NATIONAL ELECTRICAL CODE 70-309 430.51 ARTICLE 430--MOTORS,MOTOR CIRCUITS,AND CONTROLLERS would introduce additional or increased hazard(s) to a per- Table 430.52 Maximum Rating or Setting of Motor son(s) and continued motor operation is necessary for safe Branch-Circuit Short-Circuit and Ground-Fault Protective shutdown of equipment or process, a motor overload sens- Devices ing device(s) complying with the provisions of Part III of Percentage or Full-Load Current this article shall be permitted to be connected to a super- vised alarm instead of causing immediate interruption of Delay Dual Element Instantaneous Inverse Delay (Time-Delay) Trip Time the motor circuit, so that corrective acti D on or an orderly Type or Motor Fuse' Fuse' Breaker Breakerz shutdown can be initiated. Single-phase 300 175 80(} 250 motors IV. Motor Branch-Circuit Short-Circuit and AC polyphase 300 175 800 250 Ground-Fault Protection motors other than 430.51 General. Part IV specifies devices intended to pro- wound-rotor tect the motor branch-circuit conductors, the motor control Squirrel cage 300 175 800 250 apparatus, and the motors against overcurrent due to short —other than circuits or ground faults. These rules add to or amend the Design B provisions of Article 240. The devices specified in Part IV energy-efficient do not include the types of devices required by 210.8, Design B 300 175 1100 250 230.95, and 590.6. energy-efficient The provisions of Part IV shall not apply to motor cir- synchronous' 300 175 800 250 cuits rated over 600 volts, nominal. Wound rotor 150 150 800 150 FPN No. 1: For over 600 volts, nominal, see Part XI. Direct current 150 150 250 15U FPN No. 2: See Annex D, Example D8. (constant voltage) 430.52 Rating or Setting for Individual Motor Circuit. Note: For certain exceptions to the values specified, see 430.54. (A) General. The motor branch-circuit short-circuit and 'The values in the Nontime Delay Fuse column apply to Time-Delay Class CC Fuses. ground-fault protective device shall comply with 430.52(B) 2The values given in the last column also cover the ratings of nonad- and either 430.52(C) or (D), as applicable. jusiable inverse time types of circuit breakers that may be modified as in 430.52(C)(1),Exception No. 1 and No. 2. (B) All Motors.The motor branch-circuit short-circuit and 'Synchronous motors of the low-torque,low-speed type (usually 450 ground-fault protective device shall be capable of carrying rpm or lower), such as are used to drive reciprocating compressors. pumps,and so Forth,that start unloaded,do not require a fuse rating or the starting current of the motor. circuit-breaker setting in excess of 200 percent of full-load current. (C) Rating or Setting. mitted to be increased but shall in no case exceed 400 (1) In Accordance with Table 430.52. A protective de- percent of the full-load current. vice that has a rating or setting not exceeding the value (b) The rating of a time-delay(dual-element)fuse shall calculated according to the values given in Table 430.52 be permitted to be increased but shall in no case exceed shall be used. 225 percent of the full-load current. (c•) The rating of an inverse time circuit breaker shall Exception No. 1: Where the values for branch-circuit be permitted to be increased but shall in no case exceed short-circuit and ground fault protective devices deter- 400 percent for full-load currents of 100 amperes or less or mined by Table 430.52 do not correspond to the standard 300 percent for full-load currents greater than 100 amperes. sizes or ratings of fuses, nonadjustable circuit breakers, (d) The rating of a fuse of 601-6000 ampere classifi- thermal protective devices, or possible settings of adjust- cation shall be permitted to be increased but shall in no able circuit breakers, a higher size, rating, or possible set- case exceed 300 percent of the full-load current. ting that does not exceed the next higher standard ampere FPN: See Annex D, Example D8, and Figure 430.1. rating shall be permitted. Exception No. 2: Where the rating specified in Table (2) Overload Relay Table. Where maximum branch- circuit short-circuit and ground-fault protective device rat- 430.52, or the rating modified by Exception No. 1, is not ings are shown in the manufacturer's overload relay table sujficienr for the starting current of the motor: for use with a motor controller or are otherwise marked on (a) The rating of a nontime-delay fuse not exceeding the equipment, they shall not be exceeded even if higher 600 amperes or a time-delay Class CC fuse shall be per- values are allowed as shown above. 70-310 NATIONAL ELECTRICAL.CODE 2008 Edition ARTICLE 430—MOTORS,MOTOR CIRCUITS,AND CONTROLLERS 430.53 (3) Instantaneous Trip Circuit Breaker. An instanta- (5) Power Electronic Devices. Suitable fuses shall be per- neous trip circuit breaker shall be used only if adjustable mitted in lieu of devices listed in Table 430.52 for power and if part of a listed combination motor controller having electronic devices in a solid-state motor controller system, coordinated motor overload and short-circuit and ground- provided that the marking for replacement fuses is provided fault protection in each conductor, and the setting is ad- adjacent to the fuses. justed to no more than the value specified in Table 430.52. (6) Self-Protected Combination Controller. A listed self- FPN: For the purpose of this article, instantaneous trip cir- protected combination controller shall be permitted in lieu cuit breakers may include a damping means to accommo- of the devices specified in Table 430.52. Adjustable date a transient motor inrush current without nuisance trip- J ping of the circuit breaker, instantaneous-trip settings shall not exceed 1300 percent of Exception No. 1: Where the setting specified in Table full-load motor current for other than Design B energy- 430.52 is not sufficient for the starting current of the motor, efficient motors and not more than 1700 percent of full-load the setting of an instantaneous trip circuit breaker shall be motor current for Design B energy-efficient motors. permitted to be increased but shall in no case exceed FPN: Proper application of self-protected combination 1300 percent of the motor full-load current for other than controllers on 3-phase systems,other than solidly grounded Design B energy-efficient motors and no more than wye,particularly on corner grounded delta systems,consid- 1700 percent of full-load motor current for Design B ers the self-protected combination controllers' individual pole-interrupting capability. energy-e cient motors. Trip settings above 800 percent for other than Design B energy-efficient motors and above (7) Motor Short-Circuit Protector. A motor short-circuit 1100 percent for Design B energy-efficient motors shall be protector shall be permitted in lieu of devices listed in permitted where the need has been demonstrated by engi- Table 430.52 if the motor short-circuit protector is part of a neering evaluation. In such cases, it shall not be necessary listed combination motor controller having coordinated mo- to first apply an instantaneous-trip circuit breaker at for overload protection and short-circuit and ground-fault 800 percent or 1100 percent. protection in each conductor and it will open the circuit at FPN: For additional information on the requirements for a currents exceeding 1300 percent of motor full-load current motor to be classified "energy efficient," see NEMA Stan- for other than Design B energy-efficient motors and dards Publication No. MGI-1993, Revision, Motors and 1700 percent of motor full-load motor current for Design B Generators, Part. 12.59. energy-efficient motors. Exception No. 2: Where the motor full-load current is 8 amperes or less, the setting of the instantaneous-trip circuit (D) Torque Motors. Torque motor branch circuits shall be breaker with a continuous current rating of 15 amperes or protected at the motor nameplate current rating in accor- less in a listed combination motor controller that provides dance with 240,4(B), coordinated motor branch-circuit overload and short- circuit and ground fault protection shall be permitted to be 430.53 Several Motors or Loads on One Branch Cir- increased to the value marked on the controller. cuit. Two or more motors or one or more motors and other loads shall be permitted to be connected to the same branch (4) Multispeed Motor. For a multispeed motor, a single circuit under conditions specified in 430.53(D) and in short-circuit and ground-fault protective device shall be 430.53(A), (B), or (C). permitted for two or more windings of the motor, provided the rating of the protective device does not exceed the (A) Not Over 1 Horsepower. Several motors, each not above applicable percentage of the nameplate rating of the exceeding l hp in rating, shall he permitted on a nominal smallest winding protected. 120-volt branch circuit protected at not over 20 amperes or Exception: For a multispeed motor, a single short-circuit a branch circuit of 600 volts, nominal,or less,protected at not and ground fault protective device shall be permitted to be over 15 amperes, if all of the following conditions are met: used and sized according to the full-load current of the (1) The full-load rating of each motor does not exceed 6 highest current winding, where all of the following condi- amperes. tions are met: (2) The rating of the branch-circuit short-circuit and (a) Each winding is equipped with individual overload ground-fault protective device marked on any of the protection sized according to its full-load current. controllers is not exceeded. (b) The branch-circuit conductors supplying each (3) Individual overload protection conforms to 430.32, winding are sized according to the full-load current of the highest full-load current winding. (B) If Smallest Rated Motor Protected. If the branch- (c) The controller for each winding has a horsepower circuit short-circuit and ground-fault protective device is rating not less than that required for the winding having the selected not to exceed that allowed by 430.52 for the small- highest horsepower rating, est rated motor, two or more motors or one or more motors 2008 Edition NATIONAL I:UCrR1CAL CODE 70-311 430.54 ARTICLE 430—:MOTORS,MOTOR CIRCUITS,AND CONTROLLERS and other load(s), with each motor having individual over- short-circuit and ground-fault protective device, provided load protection, shall be permitted to be connected to a they comply with one of the following: branch circuit where it can be determined that the branch- (1) No conductor to the motor shall have an ampacity less circuit short-circuit and ground-fault protective device will than that of the branch-circuit conductors. not open under the most severe normal conditions of ser- (2) No conductor to the motor shall have an ampacity less vice that might be encountered. than one-third that of the branch-circuit conductors, (C) Other Group Installations. Two or more motors of with a minimum in accordance with 430.22, the con- any rating or one or more motors and other load(s), with ductors to the motor overload device being not more each motor having individual overload protection, shall be than 7.5 m(25 ft) long and being protected from physi- permitted to be connected to one branch circuit where the cal damage. motor controller(s) and overload device(s) are (1) installed (3) Conductors from the branch-circuit short-circuit and as a listed factory assembly and the motor branch-circuit ground-fault protective device to a listed manual motor short-circuit and ground-fault protective device either is controller additionally marked "Suitable for Tap Con- provided as part of the assembly or is specified by a mark- ductor Protection in Group Installations" shall be per- ing on the assembly, or (2) the motor branch-circuit short- mitted to have an ampacity not less than Vio the rating circuit and ground-fault protective device, the motor con- or setting of the branch-circuit short-circuit and troller(s), and overload device(s) are field-installed as ground-fault protective device. The conductors from separate assemblies listed for such use and provided with the controller to the motor shall have an ampacity in manufacturers' instructions for use with each other, and (3)' accordance with 430.22. The conductors from the all of the following conditions are complied with: branch-circuit short-circuit and ground-fault protective device to the controller shall (1) be suitably protected (1) Each motor overload device is listed for group instal- from physical damage and enclosed either by an en- lation with a specified maximum rating of fuse, inverse closed controller or by a raceway and be not more than time circuit breaker, or both. 3 m (10 ft) long or (2) have an ampacity not less than (2) Each motor controller is listed for group installation that of the branch-circuit conductors. with a specified maximum rating of fuse, circuit breaker, or both. 430.54 Multimotor and Combination-Load Equipment. (3) Each circuit breaker is listed and is of the inverse time The rating of the branch-circuit short-circuit and ground- type. fault protective device for multimotor and combination- (4) The branch circuit shall be protected by fuses or in- load equipment shall not exceed the rating marked on the verse time circuit breakers having a rating not exceed- equipment in accordance with 430.7(D). ing that specified in 430.52 for the highest rated motor 430.55 Combined Overcurrent Protection. Motor branch- connected to the branch circuit plus an amount equal to circuit short-circuit and ground-fault protection and motor the sum of the full-load current ratings of all other overload protection shall be permitted to be combined in a motors and the ratings of other loads connected to the single protective device where the rating or setting of the circuit. Where this calculation results in a rating less device provides the overload protection specified in 430.32. than the ampacity of the supply conductors, it shall be permitted to increase the maximum rating of the fuses 430.56 Branch-Circuit Protective Devices — In Which or circuit breaker to a value not exceeding that permit- Conductor. Branch-circuit protective devices shall comply ted by 240.4(8). with the provisions of 240.15. (5) The branch-circuit fuses or inverse time circuit break- ers are not larger than allowed by 430.40 for the over- 430.57 Size of Fuseholder. Where fuses are used for mo- load relay protecting the smallest rated motor of the for branch-circuit short-circuit and ground-fault protection, group. the fuseholders shall not be of a smaller size than required (6) Overcurrent protection for loads other than motor loads to accommodate the fuses specified by Table 430.52. shall be in accordance with Parts I through Vli of Ar- Exception: Where fuses having time delay appropriate for the ticle 240. starting characteristics of the motor are used, it shall be per- FPN: See 110.10 for circuit impedance and other mitted to use fuseholders sized to fit the fuses that are used characteristic~, 430.58 Rating of Circuit Breaker. A circuit breaker for (D) Single Motor Taps. For group installations described motor branch-circuit short-circuit and ground-fault protec- above, the conductors of any tap supplying a single motor tion shall have a current rating in accordance with 430.52 shall not be required to have an individual branch-circuit and 430.110. 70-312 NATIONAL ELECTRICAL CODE. 2008 Edition ARTICLE 430--MOTORS,MOTOR CIRCUITS,AND CONTROLLERS 430.72 V. Motor Feeder Short-Circuit and Ground-Fault (2) For a single hermetic refrigerant motor-compressor, the Protection rating permitted by 440.22 430.61 General. Part V specifies protective devices in- (3) For two or more motors, the rating permitted by 430.62 tended to protect feeder conductors supplying motors Exception: Where the feeder overcurrent device provides against overcurrents due to short circuits or grounds. the overcurrent protection for a motor control center, the FPN: See Annex D, Example DS. provisions of 430.94 shall apply. 430.62 Rating or Setting— Motor Load. VI. Motor Control Circuits (A) Specific Load.A feeder supplying a specific fixed mo- 430.71 General.Part V1 contains modifications of the gen- for load(s) and consisting of conductor sizes based on eral requirements and applies to the particular conditions of 430.24 shall be provided with a protective device having a motor control circuits. rating or setting not greater than the largest rating or setting FPN: See 430.9(B) for equipment device terminal of the branch-circuit short-circuit and ground-fault protec- requirements. tive device for any motor supplied by the feeder [based on the maximum permitted value for the specific type of a 430.72 Overcurrent Protection. protective device in accordance with 430.52, or 440.22(A) for hermetic refrigerant motor-compressors], plus the sum {A) General. A motor control circuit tapped from the load side of a motor branch-circuit short-circuit and ground-fault of the full-load currents of the other motors of the group. Where the same rating or setting of the branch-circuit Protective device(s) and functioning to control the motor{s} short-circuit and ground-fault protective device is used on connected to that branch circuit shall be protected against two or more of the branch circuits supplied by the feeder, overcurrent in accordance with 430.72. Such a tapped con- one of the protective devices shall be considered the largest tr°I circuit shall not be considered to be a branch circuit for the above calculations. and shall be permitted to be protected by either a supple- mentary or branch-circuit overcurrent protective device(s). Exception No. 1: Where one or more instantaneous trip A motor control circuit other than such a tapped control circuit breakers or motor short-circuit protectors are used circuit shall be protected against overcurrent in accordance for motor branch-circuit short-circuit and ground fault pro- with 725.43 or the notes to Table 11(A) and Table 1 I(B) in tection as permitted in 430.52(C), the procedure provided Chapter 9, as applicable, above for determining the maximum rating of the feeder protective device shall apply with the following provision: (B) Conductor Protection. The overcurrent protection for For the purpose of the calculation, each instantaneous trip conductors shall be provided as specified in 430.72(B)(1) circuit breaker or motor short-circuit protector shall be or (B)(2), assumed to have a rating not exceeding the maximum per- Exception No. 1: Where the opening of the control circuit centage of motor full-load current permitted by Table would create a hazard as,for example, the control circuit of 430.52 for the type of feeder protective device employed. a fire pump motor, and the like, conductors of control cir- Exception No. 2: Where the feeder overcurrent protective cuits shall require only short-circuit and ground fault pro- device also provides overcurrent protection for a motor tection and shall be permitted to be protected by the motor control center, the provisions of 430.94 shall apply. branch-circuit short-circuit and ground fault protective device(s). FPN: See Annex D. Example D8. Exception No. 2: Conductors supplied by the secondary (B) Other Installations. Where feeder conductors have an side of a single-phase transformer having only a two-wire ampacity greater than required by 430.24, the rating or (single-voltage) secondary shall be permitted to be pro- setting of the feeder overcurrent protective device shall tected by overcurrent protection provided on the primary be permitted to be based on the ampacity of the feeder (supply) side of the transformer, provided this protection conductors. does not exceed the value determined by multiplying the appropriate maximum rating of the overcurrent device for 430.63 Rating or Setting—Power and Lighting Loads. the secondary conductor from Table 430.72(8) by the Where a feeder supplies a motor load and, in addition, a secondary-to-primary voltage ratio. Transformer second- lighting or a lighting and appliance load, the feeder protec- ary conductors (other than two-wire) shall not be consid- tive device shall have a rating sufficient to carry the lighting ered to be protected by the primary overcurrent protection. or lighting and appliance load, plus the following: (1) Separate Overcurrent Protection. Where the motor (1) For a single motor, the rating permitted by 430.52 branch-circuit short-circuit and ground-fault protective 2008 Edition NATIONAL ELECTRICAL.CODE 70-313 430.73 ARTICLE 430—MOTORS,MOTOR CIRCUITS,AND CONTROLLERS device does not provide protection in accordance with an integral part of the motor controller and located within 430.72(B)(2), separate overcurrent protection shall be the motor controller enclosure shall be permitted to be pro- provided.The overcurrent protection shall not exceed the tected by primary overcurrent devices, impedance limiting values specified in Column A of Table 430.72(B). means, or other inherent protective means. (2) Branch-Circuit Overcurrent Protective Device.Con- (4) Primary Less Than 2 Amperes. Where the control ductors shall be permitted to be protected by the motor circuit transformer rated primary current is less than 2 am- branch-circuit short-circuit and ground-fault protective de- peres, an overcurrent device rated or set at not more than vice and shall require only short-circuit and ground-fault 500 percent of the rated primary current shall be permitted protection. Where the conductors do not extend beyond the in the primary circuit. motor control equipment enclosure, the rating of the pro- tective device(s) shall not exceed the value specified in ($) Other Means. Protection shall be permitted to be pro- Column B of Table 430.72(B). Where the conductors ex- vided by other approved means. tend beyond the motor control equipment enclosure, the 430.73 Protection of Conductor from Physical Damage. rating of the protective device(s) shall not exceed the value Where damage to a motor control circuit would constitute a specified in Column C of Table 430.72(B). hazard, all conductors of such a remote motor control cir- (C) Control Circuit IYansformer. Where a motor control cuit that are outside the control device itself shall be in- circuit transformer is provided, the transformer shall be stalled in a raceway or be otherwise suitably protected from protected in accordance with 430,72(C)(1), (C)(2), (C)(3), physical damage. (C)(4), or (C)(5). 430.74 Electrical Arrangement of Control Circuits. Exception: Overcurrent protection shall he omitted where Where one side of the motor control circuit is grounded,the the opening of the control circuit would create a hazard as, motor control circuit shall be arranged so that an accidental for example, the control circuit of a fire pump motor and ground in the control circuit remote from the motor con- the like. troller will (1) not start the motor and (2) not bypass manu- (1) Compliance with Article 725. Where the transformer ally operated shutdown devices or automatic safety shut- supplies a Class I power-limited circuit,Class 2, or Class 3 down devices. remote-control circuit complying with the requirements of 430.75 Disconnection. Article 725, protection shall comply with Article 725. (2) Compliance with Article 450. Protection shall be per- (A) General. Motor control circuits shall be arranged so that they will be disconnected from all sources of supply mitted to be provided in accordance with 45D.3. when the disconnecting means is in the open position. The (3) Less Than 50 Volt-Amperes. Control circuit trans- disconnecting means shall be permitted to consist of two or formers rated less than 50 volt-amperes (VA) and that are more separate devices, one of which disconnects the motor Table 430.72(B) Maximum Rating of Overcurrent Protective Device in Amperes Protection Provided by Motor Branch-Circuit Protective Device(s) Column A Column B Column C Separate Conductors Conductors Extend Protection Provided Within Enclosure Beyond Enclosure Control Circuit Aluminum or Aluminum or Aluminum or Conductor Copper-Clad Copper-Clad Copper-Clad Size (AWG) Copper Aluminum Copper Aluminum Copper Aluminum 18 7 — 25 — 7 — 16 10 — 40 10 — 14 (Note 11 — 100 45 — 12 (Note I (Note l) 120 100 60 45 10 (Note 1) (Note 1} 160 140 90 75 Larger than 10 (Note I} (Note I) (Note 2) (Note 2) (Note 3) (Note 3) Notes: 1. Value specified in 310.15 as applicable. 2.400 percent of value specified in Table 3 10.17 for 60°C conductors. 3. 300 percent of value specilied in Table 310.16 for 60'C conductors. 70-314 NATIONAL.HUC RICAL CODE 2008 Edition ARTICLE 430—MOTORS,MOTOR CIRCUITS,AND CONTROLLERS 430.83 and the controller from the source(s) of power supply for shall be capable of interrupting the locked-rotor current of the motor, and the other(s), the motor control circuit(s) the motor, from its power supply. Where separate devices are used, they shall be located immediately adjacent to each other. (B) Autotransformer. An auto transformer starter shall Exception No. 1: Where more than 12 motor control circuit provide an "Off' position, a running position, and at least conductors are required to be disconnected, the disconnect- one starting position. It shall be designed so that it cannot ing means shall be permitted to be located other than im- rest in the starting position or in any position that will rnediately adjacent to each other where all of the following render the overload device in the circuit inoperative. conditions are complied with: (C) Rheostats. Rheostats shall be in compliance with the (a) Access to energized parts is limited to qualified per- following: sons in accordance with Part XI of this article. (b) A warning sign is permanently located on the out- (1) Motor-starting rheostats shall be designed so that the side of each equipment enclosure door or cover permitting contact arm cannot be left on intermediate segments. access to the live purls in the motor control circuit(s), The point or plate on which the arm rests when in the warning that motor control circuit disconnecting means are starting position shall have no electrical connection remotely located and specifying the location and idenrifrcu- With the resistor. lion of each disconnect. Where energized ports are not in (2) Motor-starting rheostats for do motors operated from a an equipment enclosure as permitted by 430.232 and constant voltage supply shall be equipped with auto- 430.2,3,I, an additional warning sigm(s) shall be located matic devices that will interrupt the supply before the where visible to persons who may be working in the area of speed of the motor has fallen to less than one-third its the energized parts. normal rate. Exception No. 2: The motor control circuit disconnecting means shall be permitted to be remote from the motor con- 430.83 Ratings. The controller shall have a rating as troller power supply disconnecting means where the open- specified in 430.83(A), unless otherwise permitted in 430.83( con- ing of one or more motor control circuit disconnecting specified. (C), or as specified in (D), under the s means may result in potentially unsafe conditions for per- sonnel or property and the conditions of items (a) and (b) (A) General. of Exception No. 1 are complied with. (B) Control Transformer in Controller Enclosure. (1) Horsepower Ratings. Controllers, other than inverse Where a transformer or other device is used to obtain a time circuit breakers and molded case switches, shall have reduced voltage for the motor control circuit and is located horsepower ratings at the application voltage not lower than in the controller enclosure,such transformer or other device the horsepower rating of the motor. shall be connected to the load side of the disconnecting (2) Circuit Breaker. A branch-circuit inverse time circuit means for the motor control circuit. breaker rated in amperes shall be permitted as a controller for all motors. Where this circuit breaker is also used for VII. Motor Controllers overload protection, it shall conform to the appropriate pro- 430.81 General. Part V[[ is intended to require suitable visions of this article governing overload protection. controllers for all motors. (3) Molded Case Switch. A molded case switch rated in (A) Stationary Motor of t/e Horsepower or Less. For a amperes shall be permitted as a controller for all motors. stationary motor rated at I/8 hp or less that is normally left running and is constructed so that it cannot be damaged by (B) Small Motors. Devices as specified in 430.81{A) and overload or failure to start, such as clock motors and the {B) shall be permitted as a controller. like, the branch-circuit disconnecting means shall be per- (C) Stationary Motors of 2 Horsepower or Less. For sta- mitted to serve as the controller. tionary motors rated at 2 hp or less and 300 volts or less, the (B) Portable Motor of I/3 Horsepower or Less. For a controller shall be permitted to be either of the following: portable motor rated at 1A hp or less, the controller shall be (1) A general-use switch having an ampere rating not less permitted to be an attachment plug and receptacle. than twice the full-load current rating of the motor 430.82 Controller Design. (2) On ac circuits, a general-use snap switch suitable only for use on ac (not general-use ac-dc snap switches) (A) Starting and Stopping. Each controller shall be ca- where the motor full-load current rating is not more pable of starting and stopping the motor it controls and than 80 percent of the ampere rating of the switch 2008 Edition NATIONAL ELECTRICAL CODE 70-315 430.84 ARTICLE 430—MOTORS,MOTOR CIRCUITS,AND CONTROLt.ERS (D) Torque Motors. For torque motors, the controller equipped and connected so that they cannot be started un- shall have a continuous-duty, full-load current rating not der a weakened field. less than the nameplate current rating of the motor. For a Exception: Starting under a weakened field shall be per- motor controller rated in horsepower but not marked with the foregoing current rating, the equivalent current rating unrtted where the motor is designed for such starting. shall be determined from the horsepower rating by using 430.89 Speed Limitation. Machines of the following Table 430.247, Table 430.248, Table 430.249, or Table types shall be provided with speed-limiting devices or other 430.250, speed-limiting means: (E) Voltage Rating. A controller with a straight voltage (1) Separately excited do motors rating, for example, 240 volts or 480 volts, shall be permit- (2) Series motors ted to be applied in a circuit in which the nominal voltage (3) Motor-generators and converters that can be driven at between any two conductors does not exceed the control- excessive speed from the do end, as by a reversal of ler's voltage rating. A controller with a slash rating, for current or decrease in load example, 1201240 volts or 480Y/277 volts, shall only be ap- plied in a solidly grounded circuit in which the nominal volt- Exception: Separate speed-limiting devices or means shall age to ground from any conductor does not exceed the lower not be required under either of the following conditions: of the two values of the controller's voltage rating and the (1) Where the inherent characteristics of the machines, nominal voltage between any two conductors does not exceed the system, or the load and the mechanical connection the higher value of the controller's voltage rating. thereto are such as to safely limit the speed (2) Where the machine is always under the manual 430.84 Need Not Open All Conductors. The controller control of a qualified operator shall not be required to open all conductors to the motor. 430.90 Combination Fuseholder and Switch as Control- Exception: Where tine controller serves also as a discon- ler.The rating of a combination Fuseholder and switch used nec•ting means, it shall open all ungrounded conductors to as a motor controller shall be such that the fuseholder will the motor as provided in 430.111, accommodate the size of the fuse specified in Part III of this article for motor overload protection. 430.85 In Grounded Conductors. One pole of the con- troller shall be permitted to be placed in a permanently Exception: Where ficses having time delay appropriate for grounded conductor, provided the controller is designed so the starting characteristics of the motor are used,fusehold- that the pole in the grounded conductor cannot be opened ers of smaller size than specified in Part III of this article without simultaneously opening all conductors of the circuit, shall be permitted. 430.87 Number of Motors Served by Each Controller, VIII. Motor Control Centers Each motor shall be provided with an individual controller. 430.92 General. Part VIII covers motor control centers Exception No. 1: For motors rated 600 volts or less, a installed for the control of motors, lighting, and power single controller rated at not less than the equivalent horse- circuits. power, as determined in accordance with 430.110(C)(1), of all the motors in the group shall be permitted to serve the 430.94 Overcurrent Protection. Motor control centers group under and• of the following conditions: shall be provided with overcurrent protection in accordance (a) Where a number of motors drive several pans of a with Parts 1, II, and IX of Article 240.The ampere rating or ,single machine or piece of apparatus, such as metal and setting of the overcurrent protective device shall not exceed woodworking machines, cranes, hoists, and similar apparatus the rating of the common power bus. This protection shall (b) Where a group of motors is under the protection of be provided by (1) an overcurrent protective device located one overcurrent device as permitted in 430.53(A) ahead of the motor control center or(2) a main overcurrent (c) Where a group of motors is located in a single protective device located within the motor control center. roan). Within sight from the controller location 430.95 430.95 Service Equipment. Where used as service equip- Exception No. 2: A branch-Circuit disconnecting means ment, each motor control center shall be provided with a serving as the Controller as allowed in 430.81(A) shall be single main disconnecting means to disconnect all un- permitted to serve more than one motor, grounded service conductors. 430.88 Adjustable-Speed Motors. Adjustable-speed mo- Exception: A second service disconnect shall be permitted tors that are controlled by means of field regulation shall be to supply additional equipment. 70-316 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 430 MOTORS,MOTOR CIRCUITS,AND CONTROLLERS 430.102 Where a grounded conductor is provided, the motor (D) Spacings. Spacings between motor control center bus control center shall be provided with a main bonding jumper, terminals and other bare metal parts shall not be less than sized in accordance with 250.28(!7),within one of the sections specified in Table 430.97. for connecting the grounded conductor, on its supply side, to the motor control center equipment ground bus. (E) Barriers. Barriers shall be placed in all service- entrance motor control centers to isolate service busbars and Exception: High-impedance grounded neutral systems shall be permitted to be connected as provided in 250.36. terminals from the remainder of the motor control center. 430.96 Grounding. Multisection motor control centers 430.98 Marking. shall be connected together with an equipment grounding (A) Motor Control Centers. Motor control centers shall conductor or an equivalent equipment grounding bus sized be marked according to 110.21, and such marking shall be in accordance with Table 250.122. Equipment grounding plainly visible after installation. Marking shall also include conductors shall be connected to this equipment grounding common power bus current rating and motor control center bus or to a grounding termination point provided in a short-circuit rating. single-section motor control center. (B) Motor Control Units. Motor control units in a motor 430.97 Busbars and Conductors. control center shall comply with 430.8. (A) Support and Arrangement. Busbars shall be pro- IX. Disconnecting Means tected from physical damage and be held firmly in place. Other than for required interconnections and control wiring, 430.101 General. Part 1X is intended to require discon- only those conductors that are intended for termination in a necting means capable of disconnecting motors and con- vertical section shall be located in that section. trollers from the circuit. Exception: Conductors shall be permitted to travel hori- FPN No. 1: See Figure 430.1. zontally through vertical sections where such conductors FPN No. 2; See 110.22 for identification of disconnecting are isolated from the busbars by a barrier. means. (B) Phase Arrangement. The phase arrangement on 430.102 Location. 3-phase horizontal common power and vertical buses shall be A,B,C from front to back,top to bottom,or left to right, (A) Controller. An individual disconnecting means shall as viewed from the front of the motor control center.The B be provided for each controller and shall disconnect the phase shall be that phase having the higher voltage to controller. The disconnecting means shall be located in ground on 3-phase, 4-wire, delta-connected systems. Other sight from the controller location. busbar arrangements shall be permitted for additions to ex- Exception No. 1: For motor circuits over 600 volts, nomi- isting installations and shall be marked. nal, a controller disconnecting means capable of being Exception: Rear-mounted units connected to a vertical bus locked in the open position shall be permitted to be out of that is common to front-mounted units shall be permitted to sight of the controller, provided the controller is marked have a C, B, A phase arrangement where properly with a warning label giving the location of the disconnect- identified. ing means. Exception No. 2: A single disconnecting means shall be (C) Minimum Wire-Bending Space.The minimum wire- permitted far a group of coordinated controllers that drive bending space at the motor control center terminals and several parts of a single machine or piece of apparatus. minimum gutter space shall be as required in Article 312. The disconnecting means shall be located in sight from the Table 430.97 Minimum Spacing Between Bare Metal Parts Opposite Polarity Where Opposite Polarity Where Mounted on the Same Surface Held Free in Air Live Parts to Ground Nominal Voltage mm in. mm in. rnrn in. Not over 125 volts, nominal 19.1 !1n 12.7 �/a 12.7 '/2 Not over 250 volts, nominal 31.8 1 fa 19.1 3/4 12,7 '12 Not over 600 volts, nominal 50.9 2 25.4 l 25.4 1 2008 Edition NATIONAL ELECTRICAL CODE 70-317 430.103 ARTICLE 430—MOTORS,MOTOR CIRCUITS,AND CONTROLLERS controllers, and both the disconnecting means and the con- that no pole can be operated independently.The disconnect- trollers shall be located in sight from the machine or ing means shall be permitted in the same enclosure with the apparatus. controller. The disconnecting means shall be designed so Exception No. 3: The disconnecting means shall not be that it cannot be closed automatically. required to be in sight,from valve actuator motor (VAM) FPN: See 430.113 for equipment receiving energy from assemblies containing the controller where such a location more than one source. introduces additional or increased hazards to persons or property and conditions (a) and(b) are met. 430.104 To Be Indicating.The disconnecting means shall (u) The value actuator motor assembly is marked with plainly indicate whether it is in the open (off)or closed(on) position. a warning label giving the location of the disconnecting means. 430.105 Grounded Conductors. One pole of the discon- (b) The provision for locking or adding a lock to the netting means shall be permitted to disconnect a perma- disconnecting means shall be installed on or at the switch nendy grounded conductor, provided the disconnecting or circuit breaker used as the disconnecting means and means is designed so that the pole in the grounded conduc- shall remain in place with or without the lock installed for cannot be opened without simultaneously disconnecting (B) Motor. A disconnecting means shall be provided for a all conductors of the circuit. motor in accordance with (B)(1) or (B)(2). 430.107 Readily Accessible. At least one of the discon- (1) Separate Motor Disconnect. A disconnecting means netting means shall be readily accessible. for the motor shall be located in sight from the motor loca- tion and the driven machinery location. 430.108 Every Disconnecting Means. Every disconnect- ing means in the motor circuit between the point of attach- (2) Controller Disconnect. The controller disconnecting ment to the feeder or branch circuit and the point of con- means required in accordance with 430.IO2(A) shall be nection to the motor shall comply with the requirements of permitted to serve as the disconnecting means for the motor 430.109 and 430.110. if it is in sight from the motor location and the driven machinery location. 430.109 Type. The disconnecting means shall be a type Exception to (1) and(2): The disconnecting means for the specified in 430.109(A), unless otherwise permitted in motor shall not be required wider either condition (a) or 430.109(B) through (G), under the conditions specified. condition (b), provided the controller disconnecting means (A) General. required in accordance with 430.102(A) is individually ca- pable of being locked in the open position. The provision (1) Motor Circuit Switch. A listed motor-circuit switch for locking or adding a lock to the controller disconnecting rated in horsepower. means shall be installed on or at the switch or circuit (2) Molded Case Circuit Breaker. A listed molded case breaker used as the disconnecting means and shall remain circuit breaker. in place with or without the lock installed. (3) Molded Case Switch. A listed molded case switch. (u) Where such a location of the disconnecting means for the motor is impracticable or introduces additional or (4) Instantaneous Trip Circuit Breaker. An instanta- increased hazards to persons or property neous trip circuit breaker that is part of a listed combination (b) In industrial installations, with written safety pro- motor controller. cedures, where conditions of maintenance and supervision (5) Self-Protected Combination Controller. Listed self- ensure that only qualified persons service the equipment protected combination controller. FPN No. I: Some examples of increased or additional haz- (G) Manual Motor Controller. Listed manual motor con- ards include, but are not limited to, motors rated in excess trollers additionally marked "Suitable as Motor Diseon- of 100 hp, multimotor equipment,submersible motors,mo tors associated with adjustable speed drives, and motors nett„ shall be permitted as a disconnecting means where located in hazardous (classified) locations. installed between the final motor branch-circuit short- circuit protective device and the motor. Listed manual mo- see No. 2: For information on or Electrical procedures, for controllers additionally marked "Suitable as Motor Dis- see NFPA 70E-2004, Standard for Electrical Safety in the Workplace. connect” shall be permitted as disconnecting means on the line side of the fuses permitted in 430.52(C)(5). In this 430.103 Operation. The disconnecting means shall open case, the fuses permitted in 430.52(C)(5) shall be consid- all ungrounded supply conductors and shall be designed so ered supplementary fuses,and suitable branch-circuit short- 70-318 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 430--MOTORS,MOTOR CIRCUITS,AND CONTROLLERS 430.110 circuit and ground-fault protective devices shall be installed shall be permitted to serve as the disconnecting means. A on the line side of the manual motor controller additionally horsepower-rated attachment plug and receptacle shall not marked "Suitable as Motor Disconnect." be required for a cord-and-plug-connected appliance in ac- cordance with 422.33, a room air conditioner in accordance (7) System Isolation Equipment. System isolation equip- with 440.63, or a portable motor rated t/3 hp or less. ment shall be listed for disconnection purposes. System isolation equipment shall be installed on the load side of the (G) Torque Motors. For torque motors, the disconnecting overcurrent protection and its disconnecting means. The means shall be permitted to be a general-use switch. disconnecting means shall be one of the types permitted by 430.109(A)(1) through (A)(3), 430.110 Ampere Rating and Interrupting Capacity. (B) Stationary Motors of 'Is Horsepower or Less. For (A) General. The disconnecting means for motor circuits stationary motors of 1A hp or less, the branch-circuit over- rated 600 volts, nominal, or less shall have an ampere rat- current device shall be permitted to serve as the disconnect- ing not less than 115 percent of the full-load current rating ing means. of the motor. (C) Stationary Motors of 2 Horsepower or Less. For Exception: A listed unfused motor-circuit switch having a horsepower rating not less than the motor horsepower shall stationary motors rated at 2 hp or less and 300 volts or less, be permitted to have an ampere rating less than 115 per- devices specified in (1), (2), or (3):the disconnecting means shall be permitted [o be one of the cent of the full-load current rating of the motor, (1) A general-use switch having an ampere rating not less (B) For Torque Motors. Disconnecting means for a than twice the full-load current rating of the motor torque motor shall have an ampere rating of at least (2) On ac circuits, a general-use snap switch suitable only 115 percent of the motor nameplate current. for use on ac (not general-use ac-dc snap switches) (C) For Combination Loads. Where two or more motors where the motor full-load current rating is not more are used together or where one or more motors are used in than 80 percent of the ampere rating of the switch combination with other loads, such as resistance heaters, (3) A listed manual motor controller having a horsepower and where the combined load may be simultaneous on a single rating not less than the rating of the motor and marked disconnecting means, the ampere and horsepower ratings of "Suitable as Motor Disconnect" the combined load shall be determined as follows. (D) Autotransformer-Type Controlled Motors, For mo- (1) Horsepower Rating. The rating of the disconnecting tors of over 2 hp to and including 100 hp, the separate means shall be determined from the sum of all currents, disconnecting means required for a motor with an including resistance loads, at the full-load condition and autotransformer-type controller shall be permitted to be a also at the locked-rotor condition. The combined full-load general-use switch where all of the following provisions are current and the combined locked-rotor current so obtained met: shall be considered as a single motor for the purpose of this (1) The motor drives a generator that is provided with requirement as follows. overload protection. The full-load current equivalent to the horsepower rat- (2) The controller is capable of interrupting the locked- ing of each motor shall be selected from Table 430.247, rotor current of the motors, is provided with a no Table 430.248, Table 430.249, or Table 430.250. These voltage release, and is provided with running over- full-load currents shall be added to the rating in amperes of load protection not exceeding 125 percent of the mo- other loads to obtain an equivalent full-load current for the for full-load current rating. combined load. (3) Separate fuses or an inverse time circuit breaker rated The locked-rotor current equivalent to the horsepower or set at not more than 150 percent of the motor full- rating of each motor shall be selected from Table load current is provided in the motor branch circuit. 430.251(A) or Table 430.25I(B). The locked-rotor currents shall be added to the rating in amperes of other loads to (E) Isolating Switches. For stationary motors rated at obtain an equivalent locked-rotor current for the combined more than 40 hp do or 100 hp ac, the disconnecting means load. Where two or more motors or other loads cannot be shall be permitted to be a general-use or isolating switch started simultaneously, the largest sum of locked-rotor cur- where plainly marked "Do not operate under load." rents of a motor or group of motors that can be started simultaneously and the full-load currents of other concur- (F) Cord-and-Plug-Connected Motors. For a cord-and- rent loads shall be permitted to be used to determine the plug-connected motor, a horsepower-rated attachment plug equivalent locked-rotor current for the simultaneous com- and receptacle having ratings no less than the motor ratings bined loads. In cases where different Current ratings are 2008 Edition NATIONAL ELECTRICAL.CODE 70-319 430.111 ARTICLE 430—MOTORS.MOTOR CIRCUTrS,AND CONTROLLERS obtained when applying these tables, the largest value ob- where under expert supervision. The oil switch shall be tained shall be used. permitted to be both power and manually operable. Exception: Where part of the concurrent load is resistance 430.112 Motors Served by Single Disconnecting Means. load, and where the disconnecting means is a switch rated Each motor shall be provided with an individual discon- in horsepower and amperes, the switch used.shall be per- necting means. tnitted to have a horsepower rating that is not less than the combined load of the motor(s), ij'the ampere rating of the Exception: A single disconnecting means shall be permit- switch is not less than the locked-rotor current of the mo- ted to serve a group of motors tinder any one of the condi- tor(s)plus the resistance load. tions of(a), (b), and (c). The single disconnecting means shall be rated in accordance with 430.110(C). (2) Ampere Rating. The ampere rating of the disconnect- ing means shall not be less than 115 percent of the sum of (a) Where a number of motors drive several parts of a single machine or piece of apparatus, such as metal- and all currents at the full-load condition determined in actor- woodworking with 430.110(01). woodworking machines, cranes, and heists. (b) Where a group of motors is under the protection of Exception: A listed nonfused motor-circuit switch having a one set of branch-circuit protective devices as permitted by horsepower rating equal to or greater than the equivalent 430.53(A). horsepower of the combined loads, determined in ac•c•or- (c) Where a group of motors is in a single room within dance with 430.110(C)(1), shall be permitted to have an sight from the location of the disconnecting means. ampere rating less than 115 percent of the sum of all cur- rents at the fill-load condition. 430.113 Energy from More Than One Source. Motor (3) Small Motors. For small motors not covered by Table and motor-operated equipment receiving electric energy 430.247, Table 430.248, Table 430.249, or Table 430.250, from more than one source shall be provided with discon- the locked-rotor current shall be assumed to be six times necting means from each source of electric energy imme- the full-load current. diately adjacent to the equipment served. Each source shall be permitted to have a separate disconnecting means. 430.111 Switch or Circuit Breaker as Both Controller Where multiple disconnecting means are provided, a per- and Disconnecting Means. A switch or circuit breaker manent warning sign shall be provided on or adjacent to shall be permitted to be used as both the controller and each disconnecting means. disconnecting means if it complies with 430.11](A) and is Exception No. 1: Where a motor receives electric energy one of the types specified in 430.111(B). from more them one source, the disconnecting means for the main power supply to the motor shall not be required to be (A) General. The switch or circuit breaker complies with immediately adjacent to the motor, provided the controller the requirements for controllers specified in 430.83, opens disconnecting means is capable of being locked in the open all ungrounded conductors to the motor, and is protected by position. an overcurrent device in each ungrounded conductor (which shall be permitted to be the branch-circuit fuses). Exception No. 2: A separate disconnecting means shall not The overcurrent device protecting the controller shall be be required for a Class 2 remote-control circuit conforming permitted to be part of the controller assembly or shall be with Article 725, rated not more than 30 volts, and isolated permitted to be separate. An autotransformer-type control- and ungrounded. ler shall be provided with a separate disconnecting means. (B) Type.The device shall be one of the types specified in X. Adjustable-Speed Drive Systems 430.111(B)(1), (B)(2), or (B)(3). 430.120 General. The installation provisions of Pan I (1) Air-Break Switch. An air-break switch, operable di- through Part 1X are applicable unless modified or supple- rectl Y b applying the hand to a lever or handle. mented by Part X. Y FPN: Electrical resonance can result from the interaction (2) Inverse Time Circuit Breaker.An inverse time circuit of the nonsinusoidal currents from this type of load with breaker operable directly by applying the hand to a lever or power factor correction capacitors. handle. The circuit breaker shall be permitted to be both power and manually operable. 430.122 Conductors—Minimum Size and Ampacity. (3) Oil Switch. An oil switch used on a circuit whose (A) Branch/Feeder Circuit Conductors. Circuit conduc- rating does not exceed 600 volts or 100 amperes, or by tors supplying power conversion equipment included as special permission on a circuit exceeding this capacity part of an adjustable-speed drive system shall have an 70-320 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 430—MOTORS.MOTOR CIRCUITS,AND CONTROLLERS 430.224 ampacity not less than 125 percent of the rated input to FPN: The relationship between motor current and motor the power conversion equipment. temperature changes when the motor is operated by an ad- justable speed drive. In certain applications,overheating of (B) Bypass Device. For an adjustable speed drive system motors can occur when operated at reduced speed.even at that utilizes a bypass device, the conductor ampacity shall current levels less than $ motor's rated full-load current. not be less than required by 430.6. The ampacity of circuit The overheating can be the result of reduced motor cooling when its shaft-mounted fan is operating less than rated conductors supplying power conversion equipment in- nameplate RPM. As part of the analysis to determine cluded as part of an adjustable-speed drive system that uti- whether overheating will occur,it is necessary to consider lizes a bypass device shall be the larger of either of the the continuous torque capability curves for the motor given following: he application requirements.This will assist in determining g whether the motor overload protection will be able, on its (1) 125 percent of the rated input to the power conversion own,to provide protection against overheating.These over- equipment heating protection requirements are only intended to apply (2) t25 percent of the motor full-load current rating as to applications where an adjustable speed drive, as defined in 430.2,is used. determined by 430.6 For motors that utilize external forced air or liquid cooling systems, overtemperature can occur if the cooling 430.124 Overload Protection. Overload protection of the system is not operating.Although this issue is not unique to motor shall be provided. adjustable speed applications,externally cooled motors are most often encountered with such applications. In these (A) Included in Power Conversion Equipment. Where instances,overtemperature protection using direct tempera- the power conversion equipment is marked to indicate that ture sensing is recommended [i.e., 430.126(A)(1), (A)(3), motor overload protection is included, additional overload or (A)(4)], or additional means should be provided to en- sure that the cooling system is operating (flow or pressure protection shall not be required. Sensing,interlocking of adjustable speed drive system and (B) Bypass Circuits. For adjustable speed drive systems cooling system,etc.). that utilize a bypass device to allow motor operation at (B) Multiple Motor Applications. For multiple motor ap- rated full-load speed, motor overload protection as de- plieations, individual motor overtemperature protection scribed in Article 430, Part III, shall be provided in the shall be provided as required in 430.126(A). bypass circuit. (C) Automatic Restarting and Orderly Shutdown. The (C) Multiple Motor Applications. For multiple motor ap- provisions of 430.43 and 430.44 shall apply to the motor plication, individual motor overload protection shall be pro- overtemperature protection means. vided in accordance with Article 430, Part III. 430.128 Disconnecting Means. The disconnecting means 430.126 Motor Overtemperature Protection. shall be permitted to be in the incoming line to the conver- (A) General. Adjustable speed drive systems shall protect sion equipment and shall have a rating not less than 115 against motor overtemperature conditions where the motor Percent of the rated input current of the conversion unit. is not rated to operate at the nameplate rated current over the speed range required by the application.This protection XI. Over 600 Volts, Nominal shall be provided in addition to the conductor protection 430.221 General.Part XI recognizes the additional hazard required in 430.32. Protection shall be provided by one of g the following means. due to the use of higher voltages. It adds to or amends the (1) Motor thermal protector in accordance with 430.32 other provisions of this article. (2) Adjustable speed drive system with load and speed- 430.222 Marking on Controllers.In addition to the mark- sensitive overload protection and thermal memory re- ing required by 430.8, a controller shall be marked with the tention upon shutdown or power loss control voltage. Exception to (2): Thermal memory retention upon shut- 430.223 Conductor Enclosures Adjacent to Motors. down or power loss is not required for continuous duty Flexible metal conduit or liquidtight flexible metal conduit loads: (3) Overtemperature protection relay utilizing thermal sen- not exceeding 1.8 m (6 ft) in length shall be permitted to be employed for raceway connection to a motor terminal en- sors embedded in the motor and meeting the require- closure. ments of 430.32(A)(2) or (13)(2) (4) Thermal sensor embedded in the motor whose comnm- 430.224 Size of Conductors. Conductors supplying motors nications are received and acted upon by an adjustable shall have an ampacity not less than the current at which the speed drive system motor overload protective device(s) is selected to trip. 2008 Edition NATIONAL ELECTRICAL CODE 70-321 430.225 ARTICLF 430—MOTORS,MOTOR CIRCUITS.AND CONTROLLERS 430.225 Motor-Circuit Overcurrent Protection. where such automatic reclosing does not create a hazard to (A) General. Each motor circuit shall include coordinated persons. protection to automatically interrupt overload and fault cur- (3) Combination Protection. Overload protection and rents in the motor, the motor-circuit conductors, and the fault-current protection shall be permitted to be provided by motor control apparatus. the same device. Exception: Where a motor is vital to operation of the 430.226 Rating of Motor Control Apparatus. The ulti- plant and the motor should operate to failure if neces- mate trip current of overcurrent (overload) relays or other nary to prevent a greater hazard to persons, the sensing; motor-protective devices used shall not exceed 115 percent device(s) shall be permitted to be connected to a super- of the controller's continuous current rating, Where the mo- vised annunciator or alarm instead of interrupting the for branch-circuit disconnecting means is separate from the motor circuit. controller, the disconnecting means current rating shall not be less than the ultimate trip setting of the overcurrent (B) Overload Protection. relays in the circuit. (1) Type of Overload Device. Each motor shall be pro- 430.227 Disconnecting Means.The controller disconnect- tected against dangerous heating due to motor overloads and failure to start by a thermal protector integral with the ing means shall be capable of being locked in the open motor or external current-sensing devices, or bath. position. The provision for locking or adding a lock to the disconnecting means shall be installed on or at the switch (2) Wound-Rotor AC Motors. The secondary circuits of or circuit breaker used as the disconnecting means and shall wound-rotor ac motors, including conductors, controllers, remain in place with or without the lock installed. and resistors rated for the application, shall be considered as protected against overcurrent by the motor overload pro- XII. Protection of Live Parts—All Voltages tection means. 430.231 General. Part XI1 specifies that live parts shall (3) Operation. Operation of the overload interrupting be protected in a manner judged adequate for the hazard device shall simultaneously disconnect all ungrounded involved. conductors. (4) Automatic Reset. Overload sensing devices shall not 430.232 Where Required. Exposed live parts of motors automatically reset after trip unless resetting of the over- and controllers operating at 50 volts or more between ter- load sensing device does not cause automatic restarting of minals shall be guarded against accidental contact by en- the motor or there is no hazard to persons created by auto- closure or by location as follows: matic restarting of the motor and its connected machinery. (1) By installation in a room or enclosure that is accessible only to qualified persons (C) Fault-Current Protection. (2) By installation on a suitable balcony, gallery, or plat- (1) Type of Protection. Fault-current protection shall be form, elevated and arranged so as to exclude unquali- provided in each motor circuit as specified by either (1)(a) fied persons or (1)(b). (3) By elevation 2.5 m (8 ft) or more above the floor (a) A circuit breaker of suitable type and rating ar- Exception: Live parts of motors operating at more than 50 ranged so that it can be serviced without hazard.The circuit volts between terminals shall not require additional guard- breaker shall simultaneously disconnect all ungrounded ing for stationary motors that have commutators, collec- conductors. The circuit breaker shall be permitted to sense tors, and brush rigging located inside of motor-end brack- the fault current by means of integral or external sensing ets and not conductively connected to supply circuits elements. operating at more than 150 volts to ground. (b) Fuses of a suitable type and rating placed in each ungrounded conductor. Fuses shall be used with suitable 430.233 Guards for Attendants. Where live parts of mo- disconnecting means,or they shall be of a type that can also tors or controllers operating at over 1S0 volts to ground are serve as the disconnecting means. They shall be arranged guarded against accidental contact only by location as so that they cannot be serviced while they are energized. specified in 430.232, and where adjustment or other atten- dance may be necessary during the operation of the appa- (2) Reclosing. Fault-current interrupting devices shall not ratus, suitable insulating mats or platforms shall be pro- automatically reclose the circuit. vided so that the attendant cannot readily touch live parts Exception: Automatic reclosing of a circuit shall be per- unless standing on the mats or platforms. milted where the circuit is exposed to transient faults and FPN: For working space, see 110.26 and 110.34, 70-322 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 430—MOTORS,MOTOR CIRCUITS,AND CONTROLLERS 430.245 X111. Grounding—All Voltages Exception: Enclosures attached to ungrounded portable 430.2411 General. Part X1II specifies the grounding of ex- equipment shall not be required to be grounded. posed non–current-carrying metal parts, likely to become energized, of motor and controller frames to prevent avolt- 430.245 Method of Grounding. Connection to the equip- age aboveground in the event of accidental contact between went grounding conductor shall be done in the manner energized parts and frames. Insulation, isolation, or guard- specified in Part VI of Article 250. ing are suitable alternatives to grounding of motors under (A) Grounding Through Terminal Housings. Where the certain conditions. wiring to fixed motors is metal-enclosed cable or in metal 430.242 Stationary Motors. The frames of stationary raceways,junction boxes to house motor terminals shall be motors shall be grounded under any of the following provided, and the armor of the cable Or the metal raceways conditions: shall be connected to them in the manner specified in Ar- (1) Where supplied by metal-enclosed wiring ticle 250. (2) Where in a wet location and not isolated or guarded FPN: See 430.12(E) for equipment grounding connection (3) If in a hazardous (classified) location means required at motor terminal housings. (4) If the motor operates with any terminal at over 150 volts to ground (B) Separation of Junction Box from Motor. The junc- tion box required by 430.245(A) shall be permitted to be Where the frame of the motor is not grounded, it shall separated from the motor by not more than 1.8 m (6 ft), be permanently and effectively insulated from the ground, provided the leads to the motor are stranded conductors within Type AC cable, interlocked metal tape Type MC 430.243 Portable Motors. The frames of portable motors cable where listed and identified in accordance with that operate over 150 volts to ground shall be guarded or 250.118(10)(a), or armored cord or are stranded leads en- grounded. closed in liquidtight flexible metal conduit, flexible metal FPN No. 1: See 250.114(4) for grounding of portable ap- conduit, intermediate metal conduit, rigid metal conduit, or pliances in other than residential occupancies. electrical metallic tubing not smaller than metric designator FPN No. 2: See 250.119(C) for color of equipment 12 (trade size 3/s), the armor or raceway being connected grounding conductor. both to the motor and to the box. Exception No. 1: Listed motor-operated tools, listed Liquidtight flexible nonmetallic conduit and rigid non- motor-operated appliances, and listed motor-operated metallic conduit shall be permitted to enclose the leads to equipment shall not be required to be grounded where pro- the motor, provided the leads are stranded and the required tected by a system of double insulation or its equivalent. equipment grounding conductor is connected to both the Double-insulated equipment shall be distinctively marked motor and to the box. Exception No. 2: Listed motor-operated tools, listed motor- Where stranded leads are used, protected as specified operated appliances, and listed motor-operated equipment above, each strand within the conductor shall be not larger connected by a cord and attachment plug other than those than 10 AWG and shall comply with other requirements of required to be grounded in accordance with 250.114. this Code for conductors to be used in raceways. 430.244 Controllers. Controller enclosures shall be con- (C) Grounding of Controller-Mounted Devices. Instru- nected to the equipment grounding conductor regardless of ment transformer secondaries and exposed non–current- voltage. Controller enclosures shall have means for attach- carrying metal or other conductive parts or cases of instru- ment of an equipment grounding conductor termination in ment transformers, meters, instruments, and relays shall be accordance with 250.8. grounded as specified in 250.170 through 250.178. 2006 Edition NATIONAL.ELECTRICAL CODE 70-323 TABLE 430.247 ARTICLE 430 MOTORS,MOTOR CIRCUITS.AND CONTROLLERS XIV. Tables Table 430.247 Full-Load Current in Amperes, Direct-Current Motors The following values of full-load currents are for motors running at base speed. Armature Voltage Rating* Horsepower 90 Volts 120 Volts 180 Volts 240 Volts 500 Volts 550 Volts 1/4 4.0 3.1 2.0 1.6 - - 1/7 5.2 4.1 2.6 2.0 -- - Vi 6.8 5.4 3.4 2.7 - - '/a 9.6 7.6 4.8 3.8 - - 1 12.2 9.5 6.1 4.7 - - 11/2 - 13.2 8.3 6.6 - 2 - 17 10.8 8.5 - - 3 25 16 12.2 - - 5 40 27 20 - - 7'/2 - 58 - 29 13.6 12.2 10 - 76 - 38 18 16 15 - - - 55 27 24 20 - - - 72 34 31 25 - - - 89 43 38 30 - - - 106 51 46 40 - - - 140 67 61 50 - - --- 173 83 75 60 - - -- 206 99 90 75 - - 255 123 111 100 - - 341 164 148 125 -ti - - 425 205 185 150 w - - 506 246 222 200 - - - 675 330 294 *These are average do quantities. Table 430.248 Full-Load Currents in Amperes,Single-Phase Alternating-Current Motors The following values of full-load currents are for motors run- ning at usual speeds and motors with normal torque characteris- tics. The voltages listed are rated motor voltages. The currents listed shall be permitted for system voltage ranges of 110 to 120 and 220 to 240 volts. 115 200 208 230 Horsepower Volts Volts Volts Volts ]/r, 4.4 2.5 2.4 2.2 114 5.8 3.3 3.2 2.9 1/1 7.2 4.1 4.0 3.6 '12 9.8 5.6 5.4 4.9 j/4 13.8 7.9 7.6 6.9 1 16 9.2 8.8 8.0 11/2 20 11.5 11.0 10 2 24 13.8 13.2 12 3 34 19.6 18.7 17 5 56 32.2 30.8 28 7'/ 80 46.0 44.0 40 10 100 57.5 55.0 50 70-324 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 430-MOTORS,MOTOR CIRCUITS,AND CONTROLLERS TABLE 430.250 Table 430.249 FuII-Load Current,Two-Phase Table 430.249 Continued Alternating-Current Motors (4-Wire) The following values of full-load current are for motors running at Induction-Type Squirrel Cage and speeds usual for belted motors and motors with normal torque character- Wound Rotor(Amperes) istics.Current in the common conductor of a 2-phase,3-wire system will be 1.41 times the value given.The voltages listed are rated motor volt- ]15 460 575 2300 ages.The currents listed shall be permitted for system voltage ranges of Horsepower Volts 230 Volts Volts Volts Volts 1 10 to 120,220 to 240,440 to 480,and 550 to 600 volts. 10 - 24 12 10 - Induction-Type Squirrel Cage and 15 - 36 l8 14 - Wound Rotor(Amperes) 20 - 47 23 19 - 25 - 59 29 24 - 115 460 575 2300 30 - 69 35 28 - Horsepower Volts 230 Volts Volts Volts Volts 40 - 90 45 36 - 1/2 4.0 2.0 1.0 0.8 - 50 - 113 56 45 - `/4 4.8 2.4 1.2 1.0 - 60 - 133 67 53 14 1 6.4 3.2 1.6 1.3 - 75 - 166 83 66 18 11/2 9.0 4.5 2.3 1.8 - 100 - 218 109 87 23 2 11.8 5.9 3.0 2.4 - 125 - 270 135 108 28 3 - 8.3 4.2 3.3 150 - 312 156 125 32 5 - 13.2 6.6 5.3 -- 200 - 416 208 167 43 7'/2 - 19 9.0 8.0 - Table 430.250 Full-Load Current,Three-Pbase Alternating-Current Motors The following values of full-load currents are typical for motors running at speeds usual for belted motors and motors with normal torque characted sties. The voltages listed are rated motor voltages.The currents listed shall be permitted for system voltage ranges of 110 to 120, 220 to 240.440 to 480, and 550 to 600 volts. Synchronous-Type Unity Power Induction-Type Squirrel Cage and Wound Rotor(Amperes) Factor* (Amperes) 2300 2300 Horsepower 115 Volts 200 Volts 208 Volts 230 Volts 460 Volts 575 Volts Volts 230 Volts 460 Volts 575 Volts Volts '/2 4.4 2.5 2.4 2.2 1.1 0.9 - - - - - %4 6.4 3.7 15 3.2 1.6 1.3 - - - - - 1 8.4 4.8 4.6 4.2 2.1 1.7 - - - - - 1'/z 12.0 6.9 6.6 6.0 3.0 2.4 - - - - - 2 13.6 7.8 7.5 6.8 3.4 2.7 - - - - - 3 - 11.0 10.6 9.6 4.8 3.9 - - - - - 5 - 17.5 16.7 15.2 7.6 6.1 - - - - - 7'/z - 25.3 24.2 22 11 9 - - - - - 10 - 32.2 30.8 28 14 11 - - - 15 - 48.3 46.2 42 21 17 - - 20 - 62.1 59.4 54 27 22 - - - - 25 - 78.2 74.8 68 34 27 - 53 26 21 - 30 - 92 88 80 40 32 - 63 32 26 - 40 - 120 114 104 52 41 - 83 41 33 - 50 - 150 143 130 65 52 - 104 52 42 60 - 177 169 154 77 62 16 123 61 49 12 75 - 221 211 192 96 77 20 155 78 62 15 100 - 285 273 248 124 99 26 202 101 81 20 125 - 359 343 312 156 125 31 253 126 101 25 150 - 414 396 360 180 144 37 302 151 121 30 200 552 528 480 240 192 49 400 201 161 40 250 - - --- - 302 242 60 - - - - 300 - - - - 361 289 72 - - - - 350 - - - - 414 336 83 - - - - 400 - - -- - 477 382 95 - - - - 450 - - - - 515 412 103 - - - - 500 - - - - 590 472 118 - - - - *For 90 and 80 percent power factor, the figures shall be multiplied by 1.1 and 1.25, respectively. 2008 Edition NATIONAL ELECTRICAL CODE 70-325 TABLE 430.251(A) ARTICLE 440—MOTORS.MOTOR CIRCUITS,AND CONTROLLERS Table 430.251(A) Conversion Table of Single-Phase Locked- Rotor Currents for Selection of Disconnecting Means and Controllers as Determined from Horsepower and Voltage Rating For use only with 430.110,440.12,440.41, and 455.8(C). Maximum Locked-Rotor Current in Amperes,Single Phase Rated Horsepower 115 Volts 208 Volts 230 Volts 112 58.8 32.5 29.4 ;/a 82.8 45.8 41.4 l 96 53 48 11/2 120 66 60 2 144 80 72 3 204 113 102 5 336 186 168 71/ 480 265 240 1(l 600 332 300 Table 430.251(B) Conversion Table of Polyphase Design B, C, and D Maximum Locked-Rotor Currents for Selection of Disconnecting Means and Controllers as Determined from Horsepower and Voltage Rating and Design Letter For use only with 430.110.440.12, 440.41 and 455.8(C). Maximum Motor locked-Rotor Current in Amperes,Two- and Three-Phase, Design B, C, and D* 115 Volts 200 Volts 208 Volts 230 Volts 460 Volts 575 Volts Rated Horsepower B, C, D B, C, D B, C, D B, C, D B, C, D B, C, D 1/2 40 23 22.1 20 10 8 1/4 50 28.8 27.6 25 12.5 10 1 60 34.5 33 30 15 12 1112 80 46 44 40 20 16 2 100 57.5 55 50 25 20 3 — 73.6 71 64 32 25.6 5 — 105.8 102 92 46 36.8 71/2 — 146 140 127 63.5 50.8 10 — 186.3 179 162 81 64.8 15 — 267 257 232 116 93 20 — 334 321 290 145 116 25 — 420 404 365 183 146 30 — 500 481 435 218 174 40 — 667 641 580 290 232 50 — 834 802 725 363 290 60 — 1001 962 870 435 348 75 — 1248 1200 1085 543 434 100 1668 1603 1450 725 580 125 — 2087 2007 1815 908 726 150 — 2496 2400 2170 1085 868 200 — 3335 3207 2900 1450 1160 250 — — — — 1825 1460 300 — — — -- 2200 1760 350 — — — m-- 2550 2040 400 — — — — 2900 2320 450 — — — — 3250 2600 500 — — — — 3625 2900 *Design A motors are not limited to a maximwn starting current or locked rotor current. 70-326 NATIONAL FLECTRICAL CODE 2(X)8 Edition ARTICLE 440—AIR-CONDITIONING AND REFRIGERATING EQUIPMENT 440.4 ing evaporator coils installed, fan-coil units, remote forced ARTICLE 440 air-cooled condensers, remote commercial refrigerators, Air-Conditioning and and so forth. Refrigerating Equipment (C) Article 422. Equipment such as room air conditioners, household refrigerators and freezers, drinking water cooi- I. General ers, and beverage dispensers shall be considered appli- 440.1 Scope.The provisions of this article apply to electric ances, and the provisions of Article 422 shall also apply. motor-driven air-conditioning and refrigerating equipment (D) Other Applicable Articles.Hermetic refrigerant motor- and to the branch circuits and controllers for such equip- compressors, circuits, controllers, and equipment shall also ment. It provides for the special considerations necessary comply with the applicable provisions of Table 440.3(D). for circuits supplying hermetic refrigerant motor- compressors and for any air-conditioning or refrigerating Table 440.3(D) Other Articles equipment that is supplied from a branch circuit that sup- plies a hermetic refrigerant motor-compressor. Equipment/Occupancy Article Section Capacitors 460.9 440.2 Definitions. Commercial garages, aircraft 511, 513, Branch-Circuit Selection Current. The value in amperes hangars, motor fuel 514, 515, dispensing facilities, bulk 516, and 517 to be used instead of the rated-load current in determining storage plants, spray Part IV the ratings of motor branch-circuit conductors, disconnect- application, dipping, and ing means, controllers, and branch-circuit short-circuit and coating processes, and ground-fault protective devices wherever the running over- inhalation anesthetizing load protective device permits a sustained current greater locations Hazardous (classified) 500-503 and than the specified percentage of the rated-load current. The locations 505 value of branch-circuit selection current will always he Motion picture and television 530 equal to or greater than the marked rated-load current. studios and similar locations Resistors and reactors 470 Hermetic Refrigerant Motor-Compressor. A combina- tion consisting of a compressor and motor, both of which are enclosed in the same housing, with no external shaft or 4CO.4 Mar on Hermetic Refrigerant Motor- shaft seals, the motor operating in the refrigerant. Compressors s and Equipment. Leakage-Current Detector-Interrupter (LCDI). A de- (A) Hermetic Refrigerant Motor-Compressor Name- vice provided in a power supply cord or cord set that senses leakage current flowing between or from the cord conduc- provided with a nameplate that shall indicate the manufac- tors and interrupts the circuit at a predetermined level of turer's name, trademark, or symbol; identifying designa- tion; phase; voltage; and frequency. The rated-load current leakage current. in amperes of the motor-compressor shall be marked by the Rated-Load Current. The rated-load current for a hermetic equipment manufacturer on either or both the motor- refrigerant motor-compressor is the current resulting when the compressor nameplate and the nameplate of the equipment motor-compressor is operated at the rated load, rated voltage, in which the motor-compressor is used. The locked-rotor and rated frequency of the equipment it serves. current of each single-phase motor-compressor having a rated-load current of more than 9 amperes at 115 volts, or 440.3 Other Articles. more than 4.5 amperes at 230 volts, and each polyphase (A) Article 430. These provisions are in addition to, or motor-compressor shall be marked on the motor- amendatory of, the provisions of Article 430 and other ar- compressor nameplate. Where a thermal protector comply- ticles in this Code, which apply except as modified in this ing with 440.52(A)(2) and (13)(2) is used, the motor- article. compressor nameplate or the equipment nameplate shall be marked with the words "thermally protected."Where a pro- (B) Articles 422, 424, or 430. The rules of Articles 422, tective system complying with 440.52(A)(4) and (B)(4) is 424, or 430, as applicable, shall apply to air-conditioning used and is furnished with the equipment, the equipment and refrigerating equipment that does not incorporate a her- nameplate shall be marked with the words, "thermally pro- metic refrigerant motor-compressor. This equipment in- tected system." Where a protective system complying with cludes devices that employ refrigeration compressors 440.52(A)(4) and (13)(4) is specified, the equipment name- driven by conventional motors, furnaces with air-condition- plate shall be appropriately marked. 2008 Edition NATIONAL FLEUTRICAL CODE 70-,327 440.5 ARTICLE 430—AIR-CONDITIONING AND REFRIGERATING EQUIPMENT (B) Multimotor and Combination-Load Equipment. dance with 310.15 as applicable. The required ampacity of Multimotor and combination-load equipment shall be pro- conductors and rating of equipment shall be determined vided with a visible nameplate marked with the maker's according to 440.6(A) and 440.6(B). name, the rating in volts, frequency and number of phases, minimum supply circuit conductor ampacity, the maximum {A) Hermetic Refrigerant Motor-Compressor. For aher- ra[ing of the branch-circuit short-circuit and ground-fault metic refrigerant motor-compressor, the rated-load current protective device, and the short-circuit current rating of the marked on the nameplate of the equipment in which the motor controllers or industrial control panel. The ampacity motor-compressor is employed shall be used in determining shall be calculated by using Part IV and counting all the the rating or ampacity of the disconnecting means, the motors and other loads that will be operated at the same branch-circuit conductors, the controller, the branch-circuit time. The branch-circuit short-circuit and ground-fault pro- short-circuit and ground-fault protection, and the separate tective device rating shall not exceed the value calculated motor overload protection. Where no rated-load current is by using Part Ill. Multimotor or combination-load equip- shown on the equipment nameplate, the rated-load current ment for use on two or more circuits shall be marked with shown on the compressor nameplate shall be used. the above information for each circuit. Erc•eption No. l: Where so marked, the branch-circuit se- E.viception No. 1: Multimotor and curnbhratiorn-loud equip- lec•tion current shall be used instead of the rated-load c•ur- Inent that is suitable under the provisions of this article for rent to determine the rating or ampacity of the disconnect- c•otunec•tinn to a shr,r,Tle 15- or 20-ampere, 120-volt, or u ing means, the branch-circuit conductors, the controller, 15-ampere. 2013- or 240-volt, single-phase branch circuit and the branch-circuit short-circuit and ground fault shall be permitted to be nnarked as a sitkgle load. protection. Exception No. 2: The mininnttrt supply circuit conductor Exception No. 2: For cord-and-plug-connected equipment, ampacity and the maximuan rating of the branch-circuit the nameplate marking .shall be used in accordance with short-circuit and ground fault protective device shall not be 440.22(B), Exception No. 2. required to be marked on a room air conditioner complying FPN: For disconnecting means and controllers,see 440.12 with 440.62(A). and 440.41. Exception No. 3: Multimotor and combination-load equip- (B) Multimotor Equipment. For multimotor equipment meat used in one- and two family dwellings, cord-acrd- employing a shaded-pole or permanent split-capacitor-type attac•hrrrerrt-plug-connected equipment, or equipment sup- fan or blower motor, the full-loud current for such motor plied from a branch circuit protected at 60 A or less shall marked on the nameplate of the equipment in which the fan not be required to be marked with a short-circuit current or blower motor is employed shall be used instead of the rating. horsepower rating to determine the ampacity or rating of the disconnecting means, the branch-circuit conductors, the (C) Brandt-Circuit Selection Current.A hermetic refrig- controller, the branch-circuit short-circuit and ground-fault Brant motor-compressor, or equipment containing such a protection, and the separate overload protection.This mark- compressor, having a protection system that is approved for ing on the equipment nameplate shall not he less than the use with the motor-compressor that it protects and that per- mits continuous current in excess of the specified percent- current marked on the fan or blower motor nameplate. age of nameplate rated-load current given in 440.52(B)(2) 440.7 Highest Rated (Largest) Motor. In determining or (13)(4) shall also be marked with a branch-circuit selec- compliance with this article and with 430.24, 430.53(B) tion current that complies with 440.52(3)(2)or(13)(4).This and 430.53(C), and 430.62(A), the highest rated (largest) marking shall be provided by the equipment manufacturer motor shall be considered to be the motor that has the and shall be on the nameplate(s) where the rated-load cur- highest rated-load current. Where two or more motors have rent(s) appears. the same highest rated-load current, only one of them shall be considered as the highest rated (largest) motor. For other 440.5 Marking on Controllers. A controller shall be than hermetic refrigerant motor-compressors, and fan or marked with the manufacturer's name, trademark, or sym blower motors as covered in 440.6(B), the full-load current bol; identifying designation; voltage; phase; full-load and used to determine the highest rated motor shall be the locked-rotor current (or horsepower) rating; and such other equivalent value corresponding to the motor horsepower data may be needed to properly indicate the motor- rating selected from Table 430.248,Table 430.249, or Table compressor for which it is suitable. 430.250. 440.6 Ampaeity and Rating. The size of conductors for Exception: Where so marked, the branch-circuit selection equipment covered by this article shall be selected from current shall be used instead of the rated-load current in Table 310.16 through Table 310.19 or calculated in accor- determining the highest rated (largest) motor-compressor. 70-328 NATIONAL ELECTRICAL COOF. 2WH Edition ARTICLE 440—AIR-CONDITIONING AND REFRIGERATING EQUIPMENT 440.12 440.8 Single Machine. An air-conditioning or refrigerat- currents, including resistance loads, at the rated-load con- ing system shall be considered to be a single machine under dition and also at the locked-rotor condition.The combined the provisions of 430.87, Exception, and 430.112, Excep- rated-load current and the combined locked-rotor current so tion. The motors shall be permitted to be located remotely obtained shall be considered as a single motor for the pur- from each other. pose of this requirement as required by (1)(a) and (1)(b). (a) The full-load current equivalent to the horsepower II. Disconnecting Means rating of each motor, other than a hermetic refrigerant motor-compressor, and fan or blower motors as covered in 440.11 General. The provisions of Part II are intended to 440.6(B) shall be selected from Table 430.248, Table require disconnecting means capable of disconnecting air- 430.249,or Table 430.250.These full-load currents shall be conditioning and refrigerating equipment, including motor- added to the motor-compressor rated-load current(s) or compressors and controllers from the circuit conductors. branch-circuit selection current(s), whichever is greater, 440.12 Rating and Interrupting Capacity. and to the rating in amperes of other Ioads to obtain an equivalent full-load current for the combined load. (A) Hermetic Refrigerant Motor-Compressor.A discon- (b) The locked-rotor current equivalent to the horse- necting means serving a hermetic refrigerant motor- power rating of each motor, other than a hermetic refriger- compressor shall be selected on the basis of the nameplate ant motor-compressor, shall be selected from Table rated-load current or branch-circuit selection current, 430.251(A) or Table 430.25](B), and, for fan and blower whichever is greater, and locked-rotor current, respectively, motors of the shaded-pole or permanent split-capacitor type of the motor-compressor as follows. marked with the locked-rotor current, the marked value (1) Ampere Rating. The ampere rating shall be at least shall be used. The locked-rotor currents shall be added to 115 percent of the nameplate rated-load current or branch- the motor-compressor locked-rotor current(s) and to the rat- circuit selection current, whichever is greater. ing in amperes of other loads to obtain an equivalent locked-rotor current for the combined load. Where two or Exception: A listed unfused motor circuit switch, without more motors or other loads such as resistance heaters, or fuseholders, having a horsepower rating not less than the both, cannot be started simultaneously, appropriate combi- equivalent horsepower determined in accordance with nations of locked-rotor and rated-load current or branch- 440.12(A)(2) shall be permitted to have an ampere rating circuit selection current, whichever is greater, shall be an less than 115 percent of the specified current. acceptable means of determining the equivalent locked- (2) Equivalent Horsepower. To determine the equivalent rotor current for the simultaneous combined load. horsepower in complying with the requirements of Exception: Where p part of the concurrent load is a resis- 430.109, the horsepower rating shall be selected from Table tance load and the disconnecting means is a switch rated in 430.248, Table 430.249, or Table 430.250 corresponding to horsepower and amperes, the switch used shall be permit- the rated-load current or branch-circuit selection current, ted to have a horsepower rating not less than the combined whichever is greater, and also the horsepower rating from load to the motor-compressor(s) and other motor(s) at the Table 430.251(A)or Table 430.251(B)corresponding to the locked-rotor condition, if the ampere rating of the switch is locked-rotor current. In case the nameplate rated-load cur- not less than this locked-rotor load plus the resistance load, rent or branch-circuit selection current and locked-rotor current do not correspond to the currents shown in Table (2) Full-Load Current Equivalent. The ampere rating of 430.248, Table 430.249, Table 430.250, Table 430.251(A), the disconnecting means shall be at least 115 percent of the or Table 430.251(B), the horsepower rating corresponding sum of all currents at the rated-load condition determined to the next higher value shall be selected. In case different in accordance with 440.12(B)(1). horsepower ratings are obtained when applying these Exception: A listed unfured motor circuit switch, without tables, a horsepower rating at least equal to the larger of the fuseholders, having a horsepower rating not less than the values obtained shall be selected. equivalent horsepower determined by 440.12(B)(1)shall be (B) Combination Loads.Where the combined load of two permitted to have an ampere rating less than 115 percent of or more hermetic refrigerant motor-compressors or one or the sum of all currents. more hermetic refrigerant motor-compressor with other motors or loads may be simultaneous on a single discon- (C) Small Motor-Compressors. For small motor- compressors not having the locked-rotor current marked on necting means, the rating for the disconnecting means shall the nameplate, or for small motors not covered by Table be determined in accordance with 440.12(B)(1) and (13)(2). 430.247, Table 430.248, Table 430.249, or Table 430.250, (1) Horsepower Rating.The horsepower rating of the dis- the locked-rotor current shall be assumed to be six times connecting means shall be determined from the sum of all the rated-load current. 2008 Edition NATIONAL ELECTRICAL CODE 70-329 440.13 ARTICLE 440—AIR-CONDITIONING AND REFRIGERATING EQUIPMENT (D) Disconnecting Means. Every disconnecting means in apparatus,and motors in circuits supplying hermetic refrig- the refrigerant motor-compressor circuit between the point erant motor-compressors against overcurrent due to short of attachment to the feeder and the point of connection to circuits and ground faults.They are in addition to or amen- the refrigerant motor-compressor shall comply with the re- datory of the provisions of Article 240. quirements of 440.12. (E) Disconnecting Means Rated in Excess of 100 Horse- 440.22 Application and Selection. power. Where the rated-load or locked-rotor current as de- (A) Rating or Setting for Individual Motor-Compressor. termined above would indicate a disconnecting means rated The motor-compressor branch-circuit short-circuit and in excess of 100 hp, the provisions of 430.109(E) shall ground-fault protective device shall be capable of carrying apply. the starting current of the motor.A protective device having a rating or setting not exceeding 175 percent of the motor- 440.13 Cord-Connected Equipment. For cord-connected compressor rated-load current or branch-circuit selection equipment such as room air conditioners, household refrig- current, whichever is greater, shall be permitted, provided erators and freezers, drinking water coolers, and beverage that, where the protection specified is not sufficient for the dispensers, a separable connector or an attachment plug and starting current of the motor, the rating or setting shall be receptacle shall be permitted to serve as the disconnecting permitted to be increased but shall not exceed 225 percent means. of the motor rated-load current or branch-circuit selection FPN: For room air conditioners, see 440.63. current, whichever is greater. Exception: The rating of the branch-circuit short-circuit 440.14 Location. Disconnecting means shall be located and ground-fault protective device shall not be required to within sight from and readily accessible from the air- conditioning or refrigerating equipment.The disconnecting be less than 15 amperes. means shall be permitted to be installed on or within the (E) Rating or Setting for Equipment. The equipment air-conditioning or refrigerating equipment. branch-circuit short-circuit and ground-fault protective device The disconnecting means shall not be located On panels shall be capable of carrying the starting current of the equip- that are designed to allow access to the air-conditioning or ment.Where the hermetic refrigerant motor-compressor is the refrigeration equipment or to obscure the equipment name- only load on the circuit, the protection shall comply with plate(s). 440.22(A). Where the equipment incorporates more than one Exception No. 1: Where the disconnecting means provided hermetic refrigerant motor-compressor or a hermetic refriger- in accordance with 430.102(A) is capable of being locked ant motor-compressor and other motors or other loads, the in the open position, and the refrigerating or air- equipment short-circuit and ground-fault protection shall com- conditioning equipment is essential to an industrial process ply with 430.53 and 440.22(B)(1) and (B)(2). in a facility with written safety procedures, and where the conditions of maintenance crud supervision ensure that only (1 ) Motor-Compressor Largest Load. Where a hermetic qualified persons service the equipment, a disconnecting refrigerant motor-compressor is the largest load connected means within sight frottl the equipment ,hull not be re- to the circuit, the rating or setting of the branch-circuit quired. The provision for locking or adding a lock to the short-circuit and ground-fault protective device shall not disconnecting cleans shall be installed on or at the switch exceed the value specified in 440.22(A) for the largest or circuit breaker and shall remain in place with or without motor-compressor plus the sum of the rated-load current or the lock installed branch-circuit selection current, whichever is greater,of the Exception No. 2: Where an attachment plug and receptacle other motor-compressor(s) and the ratings of the other serve as the disconnecting means in accordance with loads supplied. 440.13, their location shall be accessible but shall not be (2) Motor-Compressor Not Largest Load. Where a her- required to be readily accessible. metic refrigerant motor-compressor is not the largest load FPN: See Parts VII and IX of Article 430 for additional connected to the circuit, the rating or setting of the branch- requirements. circuit short-circuit and ground-fault protective device shall not exceed a value equal to the sum of the rated-load cur- rent or branch-circuit selection current, whichever is III. Branch-Circuit Short-Circuit and Ground-Fault greater,rating(s) for the motor-compressor(s) plus the value Protection specified in 430.53(C)(4) where other motor loads are sup- 440.21 General.The provisions of Part lit specify devices plied, or the value specified in 240.4 where only nonmotor intended to protect the branch-circuit conductors, control loads are supplied in addition to the motor-compressor(s). 70-330 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 440—AIR-CONDPI'IONING AND REFRIGERATING EQUIPMENT 440.41 Exception No. 1: Equipment that starts and operates on a motor-compressor(s) with or without an additional load(s) 15- or 20-ampere 120-volt, or 15-ampere 208- or 240-volt shall have an ampacity not less than the sum of the rated- single-phase branch circuit, shall be permitted to be pro- load or branch-circuit selection current ratings, whichever tected by the 15- or 20-ampere overcurrent device protect- is larger, of all the motor-compressors plus the full-toad ing the branch circuit, but if the maximum branch-circuit currents of the other motors, plus 25 percent of the highest short-circuit and ground fault protective device rating motor or motor-compressor rating in the group. marked on the equipment is less than these values, the circuit protective device shall not exceed the value marked Exception No. 1: Where the circuitry is interlocked so as to the equipment nameplate. prevent the starting and running of a second motor- on or group of motor-compressors, the conductor Exception No. 2: The nameplate marking of cord-and- size shall be determined from the largest motor-compressor plug-connected equipment rated not greater than 250 volts, or group of motor-compressors that is to be operated at a single-phase, such as household refrigerators and freezers, given time. drinking water coolers, and beverage dispensers, shall be used in determining the branch-circuit requirements, and Exception No. 2: The branch-circuit conductors for room each unit shall be considered as a single motor unless the air conditioners shall be in accordance with Part Vll of nameplate is marked otherwise. Article 440. (C) Protective Device Rating Not to Exceed the Manu- 440.34 Combination Load. Conductors supplying a facturer's Values. Where maximum protective device rat- motor-compressor load in addition to a lighting or appli- ings shown on a manufacturer's overload relay table for use ance load as calculated from Article 220 and other appli- with a motor controller are less than the rating or setting cable articles shall have an ampacity sufficient for the light- selected in accordance with 440.22(A) and (B), the protec- ing or appliance load plus the required ampacity for the tive device rating shall not exceed the manufacturer's val- motor-compressor load determined in accordance with ues marked an the equipment. 440.33 or, for a single motor-compressor, in accordance with 440.32. IV. Branch-Circuit Conductors Exception: Where the circuitry is interlocked so as to pre- 440.31 General.The provisions of Part IV and Article 310 vent simultaneous operation of the motor-compressor(s) specify ampacities of conductors required to carry the mo- and all other loads connected, the conductor size shall be for current without overheating under the conditions speci- determined from the largest size required for the motor- fied, except as modified in 440.6(A), Exception No. 1, compressor(s)and other loads to be operated at a given time. The provisions of these articles shall not apply to inte- gral conductors of motors,to motor controllers and the like, 440.35 Multimotor and Combination-Load Equipment. or to conductors that form an integral part of approved The ampacity of the conductors supplying multimotor and equipment. combination-load equipment shall not be less than the mini- mum circuit ampacity marked on the equipment in accor- dance with 440.4(B). 440.32 Single Motor-Compressor.Branch-circuit conduc- tors supplying a single motor-compressor shall have an am- V. Controllers for Motor-Compressors pacity not less than 125 percent of either the motor- compressor rated-load current or the branch-circuit 440.41 Rating. selection current, whichever is greater. For current, whichever connected motor-compressor, (A) Motor-Compressor Controller. A motor-compressor the selection of branch-circuit conductors between the con- controller shall have both acontinuous-duty full-load cur- troller and the motor-compressor shall be permitted to be rent rating and a locked-rotor current rating not less than based on 72 percent of either the motor-compressor rated- the nameplate rated-load current or branch-circuit selection load current or the branch-circuit selection current, which- current, whichever is greater, and locked-rotor current, re- ever is greater. spectively, of the compressor. In case the motor controller is rated in horsepower but is without one or both of the FPN: The individual motor circuit conductors of wye-start, foregoing current ratings, equivalent currents shall be de- delta-run connected motor-compressors carry 58 percent of termined from the ratings as follows. Table 430.248, Table the rated load current. The multiplier of 72 percent is ob- tained by multiplying 58 percent by 1.25. 430.249, and Table 430.250 shall be used to determine the equivalent full-load current rating. Table 430.25](A) and 440.33 Motor-Compressor(s) With or Without Addi- Table 430.251(13) shall be used to determine the equivalent tional Motor Loads. Conductors supplying one or more locked-rotor current ratings. 2008 Edition NATIONAL ELECTRICAL CODE 70-331 440.51 ARTICLE 440 AIR-CONDITIONING AND REFRIGERATING EQUIPMENT (B) Controller Serving More Than One Load.A control- ranged so that the opening of the control circuit will ler serving more than one motor-compressor or a motor- result in interruption of current to the motor- compressor and other loads shall have a continuous-duty compressor. full-load current rating and a locked-rotor current rating not less than the combined load as determined in accordance (B) Protection of Motor-Compressor Control Appara- with 440.12(B). tus and Branch-Circuit Conductors. The motor- compressor controller(s), the disconnecting means, and the branch-circuit conductors shall be protected against over- VI. Motor-Compressor and Branch-Circuit Overload current due to motor overload and failure to start by one of Protection the following means, which shall be permitted to be the 440.51 General.The provisions of Part VI specify devices same device or system protecting the motor-compressor in intended to protect the motor-compressor,the motor-control accordance with 440.52(A): apparatus, and the branch-circuit conductors against exces- Exception: Overload protection of motor-compressors and sive heating due to motor overload and failure to start. equipment on 15-and 20-ampere, single-phase, branch cir- FPN: See 240.4(G) for application of Parts III and VI of suits shall be permitted to be in accordance with 440.54 Article 440. and 440.55. (1) An overload relay selected in accordance with 440.52 Application and Selection. 440.52(A)(1) (A) Protection of Motor-Compressor. Each motor- (2) A thermal protector applied in accordance with compressor shall be protected against overload and failure 440.52(A)(2), that will not permit a continuous current to start by one of the following means: in excess of 156 percent of the marked rated-load cur- 0) A separate overload relay that is responsive to motor- rent or branch-circuit selection current compressor current.This device shall be selected to trip (3) A fuse or inverse time circuit breaker selected in accor- at not more than 140 percent of the motor-compressor dance with 440.52(A)(3) rated-load current. (4) A protective system, in accordance with 440.52(A)(4), (2) A thermal protector integral with the motor-com- that will not permit a continuous current in excess of pressor, approved for use with the motor-compressor 156 percent of the marked rated-load current or branch- that it protects on the basis that it will prevent danger- circuit selection current ous overheating of the motor-compressor due to over- load and failure to start. If the current-interrupting de- 440.53 Overload Relays. Overload relays and other de- vice is separate from the motor-compressor and its vices for motor overload protection that are not capable of control circuit is operated by a protective device inte- opening short circuits shall be protected by fuses or inverse gral with the motor-compressor, it shall be arranged so time circuit breakers with ratings or settings in accordance that the opening of the control circuit will result in with Part III unless identified for group installation or for interruption of current to the motor-compressor. part-winding motors and marked to indicate the maximum (3) A fuse or inverse time circuit breaker responsive to size of fuse or inverse time circuit breaker by which they motor current, which shall also be permitted to serve as shall be protected. the branch-circuit short-circuit and ground-fault protec- Exception. The fi4se or inverse time circuit breaker size tive device. This device shall be rated at not more than marking shall be permitted on the nameplate of the equipment 125 percent of the motor-compressor rated-load cur- in which the overload relay or other overload device is used. rent. It shall have sufficient time delay to permit the motor-compressor to start and accelerate its load. The 440,54 Motor-Compressors and Equipment on 15- or equipment or the motor-compressor shall be marked 20-Ampere Branch Circuits — Not Cord-and- with this maximum branch-circuit fuse or inverse time Attachment-Plug-Connected. Overload protection for circuit breaker rating. motor-compressors and equipment used on 15- or 20- (4) A protective system, furnished or specified and ap- ampere 120-volt, or 15-ampere 208- or 240-volt single- proved for use with the motor-compressor that it pro- phase branch circuits as permitted in Article 210 shall be tests on the basis that it will prevent dangerous over- permitted as indicated in 440.54(A) and 440.54(B). heating of the motor-compressor due to overload and failure to start. If the current-interrupting device is (A) Overload Protection. The motor-compressor shall separate from the motor-compressor and its control cir- be provided with overload protection selected as speci- cuit is operated by a protective device that is not inte- fied in 440.52(A). Both the controller and motor over- gral with the current-interrupting device, it shall be ar- load protective device shalt be identified for installation 70-332 NATIONAL ELECTRICAL CODE 2(x)8 Edition ARTICLE 440—AIR-CONDITIONING AND REFRIGERATING EQUIPMENT 440,65 with the short-circuit and ground-fault protective device for 440.62 Branch-Circuit Requirements. the branch circuit to which the equipment is connected. (A) Room Air Conditioner as a Single Motor Unit. A (B) Time Delay.The short-circuit and ground-fault protec- room air conditioner shall be considered as a single motor tive device protecting the branch circuit shall have suffi- unit in determining its branch-circuit requirements where cient time delay to permit the motor-compressor and other all the following conditions are met; motors to start and accelerate their loads, (1) It is cord-and-attachment-plug-connected. (2) Its rating is not more than 40 amperes and 250 volts, 440.55 Cord-and-Attachment-Plug-Connected Motor- single phase. Compressors and Equipment on IS- or 20-Ampere (3) Total rated-load current is shown on the room air- Branch Circuits. Overload protection for motor- conditioner nameplate rather than individual motor cur- compressors and equipment that are cord-and-attachment- rents, plug-connected and used on 15- or 20-ampere 120-volt, or (4) The rating of the branch-circuit short-circuit and 15-ampere 208-or 240-volt, single-phase branch circuits as ground-fault protective device does not exceed the am- permitted in Article 210 shall be permitted as indicated in pacity of the branch-circuit conductors or the rating of 440.55(A), (B), and (C). the receptacle, whichever is less, (A) Overload Protection. The motor-compressor shall be (g) Where No Other Loads Are Supplied. The total provided with overload protection as specified in marked rating of a cord-and-attachment-plug-connected 440.52(A). Both the controller and the motor overload pro- room air conditioner shall not exceed 80 percent of the tective device shall be identified for installation with the rating of a branch circuit where no other loads are supplied. short-circuit and ground-fault protective device for the branch circuit to which the equipment is connected. (C) Where Lighting Units or Other Appliances Are Also Supplied. The total marked rating of a cord-and- (B) Attachment Plug and Receptacle Rating. The rating attachment-plug-connected room air conditioner shall not of the attachment plug and receptacle shall not exceed 20 exceed 50 percent of the rating of a branch circuit where amperes at 125 volts or 15 amperes at 250 volts. lighting outlets,other appliances,or general-use receptacles (C) Time Delay.The short-circuit and ground-fault protec- are also supplied. Where the circuitry is interlocked to pre- live device protecting the branch circuit shall have suf vent simultaneous operation of the room air conditioner and y- energization of other outlets on the same branch circuit, a cient time delay to permit the motor-compressor and other cord-and-attachment-plug-connected room air conditioner motors to start and accelerate their loads. shall not exceed 80 percent of the branch-circuit rating. VII. Provisions for Room Air Conditioners 440.63 Disconnecting Means.An attachment plug and re- ceptacle shall be permitted to serve as the disconnecting 440.60 General. The provisions of Part VII shall apply to means for asingle-phase room air conditioner rated 250 electrically energized room air conditioners that control volts or less if (1) the manual controls on the room air temperature and humidity. For the purpose of Part VII, a conditioner are readily accessible and located within 1.8 m room air conditioner (with or without provisions for heat- (6 ft) of the floor or (2) an approved manually operable ing)shall be considered as an ac appliance of the air-cooled disconnecting means is installed in a readily accessible lo- window, console, or in-wall type that is installed in the cation within sight from the room air conditioner. conditioned room and that incorporates a hermetic refriger- ant motor-compressor(s). The provisions of Part VII cover 440,f4 Supply Cords. Where a flexible cord is used to equipment rated not over 250 volts, single phase, and such supply a room air conditioner, the length of such cord shall equipment shall be permitted to be cord-and-attachment- not exceed 3.0 m (10 ft) for a nominal, 120-volt rating or plug-connected. I.8 m (6 ft) for a nominal, 208- or 240-volt rating. A room air conditioner that is rated 3-phase or rated over 250 volts shall be directly connected to a wiring 440,65 Leakage-Current Detector-Interrupter (LCDI) method recognized in Chapter 3, and provisions of Part VII and Arc-Fault Circuit Interrupter (AFCI). Single-phase shall not apply. cord-and-plug-connected room air conditioners shall be provided with factory-installed LCD1 or AFCI protection. 440.61 Grounding, The enclosures of room air condition- The LCDI or AFCI protection shall be an integral part of ers shall be connected to the equipment grounding conduc- the attachment plug or be located in the power supply cord for in accordance with 250.110, 250.112, and 250.114. within 300 mm (12 in,) of the attachment plug. 2008 Edition NATIONAL ELECTRICAL CODE 70-333 345.1 ARTICLE 445--GENERATORS interlocked so that no one pole can be opened without si- ARTICLE 445 multaneously disconnecting both leads of the armature Generators from the system. Ktception to (A)through (E): Where deemed by the author- 445.1 Scope. This article covers the installation of gen- ity having jurisdiction that a generator is vital to the op- erators. eration of an electrical system and the generator should operate to failure to prevent a greater hazard to persons, 445.10 location. Generators shall be of a type suitable for the overload sensing device(s)shall be permitted to be con- the locations in which they are installed. They shall also netted to an annunciator or alarm supervised by autho- meet the requirements for motors in 430.14. rized personnel instead of interrupting the generator circuit. 445.11 Marking. Each generator shall be provided with a 445.13 Ampacity of Conductors. The ampacity of the nameplate giving the manufacturer's name, the rated fre- quency, power factor, number of phases if of alternating conductors from the generator terminals to the first distri- bution device(s) containing overcurrent protection shall not current, the sub[ransient and transient impedances, the rat- ing in kilowatts or kilovolt amperes, the normal volts and be less than 115 percent of the nameplate current rating of amperes corresponding to the rating, rated revolutions per the generator. It shall be permitted to size the neutral con- ductors in accordance with 220.61. Conductors that must minute, insulation system class and rated ambient tempera- lure or rated temperature rise, and time rating. carry ground-Fault currents shall not be smaller than re- quired by 250.30(A). Neutral conductors of do generators 445.12 Overcurrent Protection. that must carry ground-fault currents shall not be smaller than the minimum required size of the largest conductor. (A) Constant-Voltage Generators. Constant-voltage gen- Exception: Where the design and operation of the genera- erators, except ac generator exciters, shall be protected tar prevent overloading, the ampacity of the conductors from overloads by inherent design, circuit breakers, Fuses, or other acceptable overcurrent protective means suitable shall not be less than 100 percent of the nameplate current for the conditions of use. rating of the generator. (B) Two-Wire Generators. Two-wire, do generators shall 445.14 Protection of Live Parts. Live parts of generators be permitted to have overcurrent protection in one conduc- operated at more than 50 volts to ground shall not be ex- tor only if the overcurrent device is actuated by the entire posed to accidental contact where accessible to unqualified current generated other than the current in the shunt field. persons. The overcurrent device shall not open the shunt field. 445.15 Guards for Attendants. Where necessary for the (C) 65 Volts or Less. Generators operating at 65 volts or safety of attendants, the requirements of 430.233 shall less and driven by individual motors shall be considered as apply protected by the overcurrent device protecting the motor if these devices will operate when the generators are delivering 445.16 Bushings. Where wires pass through an opening in not more than 150 percent of their full-load rated current. an enclosure, a conduit box, or a barrier, a bushing shall be used to protect the conductors from the edges of an opening (D) Balancer Sets. Two-wire, do generators used in con- having sharp edges. The bushing shall have smooth, well- junction with balancer sets to obtain neutral points for rounded surfaces where it may be in contact with the con- 3-wire systems shall be equipped with overcurrent devices ductors. If used where oils, grease, or other contaminants that disconnect the 3-wire system in case of excessive un- may be present, the bushing shall be made of a material not balancing of voltages or currents. deleteriously affected. (E) Three-Wire, Direct-Current Generators. Three- 445.17 Generator Terminal Housings. Generator termi- wire, do generators, whether compound or shunt wound, nal housings shall comply with 430.12. Where a horse- shall be equipped with overcurrent devices, one in each power rating is required to determine the required mini- armature lead, and connected so as to be actuated by the mum size of the generator terminal housing, the full-load entire current from the armature. Such overcurrent devices current of the generator shall be compared with comparable shall consist either of a double-pole, double-coil circuit motors in Table 430.247 through Table 430.250.The higher breaker or of a 4-pole circuit breaker connected in the main horsepower rating of Table 430.247 and Table 430.250 and equalizer leads and tripped by two overcurrent devices, shall be used whenever the generator selection is between one in each armature lead. Such protective devices shall be two ratings. 70-334 NfATTONAL ELECTRICAL CODE 2008 Edition ARTICLE 450—TRANSFORMERS AND TRANSFORMER VAULTS(INCLUDING SECONDARY TIES) 450.4 445,18 Disconnecting Means Required for Generators. This article also covers the installation of transformers Generators shall be equipped with disconnect(s), lockable in hazardous (classified) locations as modified by Articles in the open position, by means of which the generator and 501 through 504. all protective devices and control apparatus are able to be disconnected entirely from the circuits supplied by the gen- erator except where both of the following conditions apply: I. General Provisions (1) The driving means for the generator can be readily shut 450.2 Definition. For the purpose of this article, the fol- down. lowing definition shall apply. (2) The generator is not arranged to operate in parallel with Transformer. An individual transformer, single- or another generator or other source of voltage, polyphase, identified by a single nameplate, unless other- 445.19 Generators Supplying Multiple Loads. A single wise indicated in this article. generator supplying more than one load, or multiple gen.- 450.3 Overcurrent Protection. Overcurrent protection of eratolrs operating in parallel, shall be permitted to supply transformers shall comply with 450.3(A), (B), or (C). As either of the following: used in this section, the word transformer shall mean a (1) A vertical switchboard with separate sections transformer or polyphase bank of two or more single-phase (2) Individual enclosures with overcurrent protection transformers operating as a unit. tapped from a Single feeder for load separation. and FPN No. 1: See 240.4, 240.21, 240.100, and 240.101 for distribution. ovcrcurrent protection of conductors. FPN No. 2: Nonlinear loads can increase heat in a trans- former without operating its overcurrent protective device. ARTICLE 450 (A) Transformers Over 600 Volts, Nominal. Overcurrent protection shall be provided in accordance with Table Transformers and Transformer Vaults 450.3(A). (Including Secondary Ties) (B) Transformers 600 Volts, Nominal, or Less. Overcur- rent protection shall be provided in accordance with Table 450.1 Scope. This article covers the installation of all 450.3(B). transformers. Exception: Where the transformer is installed as a motor- Exception No. I: Current transformers. control circuit transformer in accordance with 430.72(C)(I) Exception No. 2: Dry-type transformers that constitute a through (C)(5). component part of other apparatus and comply with the requirements for such apparatus. (C) Voltage Transformers. Voltage transformers installed Exception No. 3: Transformers that are an integral part of indoors or enclosed shall be protected with primary fuses. an X-ray, high frequency, or electrostatic-coating FPN: For protection of instrument circuits including volt- apparatus. age transformers, see 408.52. Exception No. 4: Transformers used with Class 2 and 450.4 Autotransformers 600 Volts, Nominal, or Less. Class 3 circuits that comply with Article 725. (A) Overcurrent Protection. Each autotransformer 600 Exception No. 5: Transformers for sign and outline light- volts, nominal, or less shall be protected by an individual ing that comply with Article 60(1. overcurrent device installed in series with each ungrounded Exception No. 6: Transformers for electric-discharge light- input conductor. Such overcurrent device shall be rated or ing that comply with Article 410. set at not more than 125 percent of the rated full-load input Exception No. 7: Transformers used for power-limited fire current of the autotransformer. Where this calculation does alarm circuits that comply with Part III of Article 760. not correspond to a standard rating of a fuse or nonadjust- Exception No. 8: Transformers used for research, develop- able circuit breaker and the rated input current is 9 amperes ment, or testing, where effective arrangements are provided or more, the next higher standard rating described in 240.6 to safeguard persons from contacting energized parts. shall be permitted. An overcurrent device shall not be in- stalled in series with the shunt winding (the winding com- This article covers the installation of transformers dedi- mon to both the input and the output circuits) of the au- cated to supplying power to a fire pump installation as totransformer between Points A and B as shown in Figure modified by Article 695. 450.4. 2008 Edition NATIONAL ELECTRICAL CODE 70-335 450.5 ARTICLE 4S0-TRANSFORMERS AND TRANSFORMER VAULTS(INCLUDING; SECONDARY TIES) Table 450.3(A) Maximum Rating or Setting of Overcurrent Protection for Transformers Over 600 Volts (as a Percentage of Transformer-Rated Current) Secondary Protection (See Note 2.) Primary Protection over 600 - Volts Over 600 Volts 600 Volts or Less Location Transformer Circuit Breaker Circuit Breaker Circuit Breaker Limitations Rated Impedance (See Note 4.) Fuse Rating (See Note 4.) Fuse Rating or Fuse Rating Not more than 6%n 600% 300% 30017o 250% 125% (See Note 1.) (See Note 1.) (See Note 1.) (See Note 1.) (See Note L) Any location More than 617r, and 400%n 300%n 250%n 225%n 125% not more than 10% (See Note 1.) (See Note 1.) (See Note l.) (See Note 1.) (See Note 1.) Supervised Any 300% 250% Not required Not required Not required locations (See Note 1.) (See Note 1.) only (See Note 3.) Not more than 6% 600% 300% 300% 250%n 250% (See Note 5.) (See Note 5.) (See Note 5.) More than 6% 400% 300% 250% 225%n 250% and not more (See Note 5.) (See Note 5.) (See Note 5.) than 10% Notes: 1.Where the required fuse rating or circuit breaker setting does not correspond to a standard rating or setting,a higher rating or setting that does not exceed the next higher standard rating or setting shall be permitted. 2.Where secondary overcurrent protection is required,the secondary overcurrent device shall be permitted to consist of not more than six circuit breakers or six sets of fuses grouped in one location.Where multiple overcurrent devices are utilized, the total of all the device ratings shall not exceed the allowed value of a single overcurrent device.If both circuit breakers and fuses are used as the overcurrent device,the total of the device ratings Shall not exceed that allowed for fuses. 3.A supervised location is a location where conditions of maintenance and supervision ensure that only qualified persons monitor and service the transformer installation. 4. Electronically actuated fuses That may be set to open at a specific current shall be set in accordance with settings for circuit breakers. 5. A transformer equipped with a coordinated thermal overload protection by the manufacturer shall be permitted to have separate secondary protection omitted. 450.5 Grounding Autotransformers. Grounding au- totransformers covered in this section are zigzag or T connected transformers connected to 3-phase, 3-wire un- grounded systems for the purpose of creating a 3-phase, A 4-wire distribution system or providing a neutral point for Shunt winding(s) grounding purposes. Such transformers shall have a con- tinuous per-phase current rating and a continuous neutral current rating. Zig-zag connected transformers shall not be B installed on the load side of any system grounding connec- Figure 450.4 Autotransformer. tion, including those made in accordance with 250.24(B), 250.30(A)(1), or 250.32(B) Exception. Exception; Where the rated input current of the autotrans- FPN: The phase current in a grounding autotransfotmer is former is less than 9 amperes, an overcurrent device rated one-third the neutral current. or set at not more than 167 percent of the input current (A) Three-Phase,4-Wire System.A grounding autotrans- .shall he permitted. former used to create a 3-phase, 4-wire distribution system (B) Transformer Field-Connected as an Autotrans- from a 3-phase,3-wire ungrounded system shall conform to former. A transformer Field-connected as an autotrans- 450.5(A)(1) through (A)(4). former shall be identified for use at elevated voltage. (1) Connections. The transformer shall be directly con- FPN: For information on permitted uses or autotransform- nected to the ungrounded phase conductors and shall not be ers, see 2109 and 215.11. switched or provided with overcurrent protection that is 70-336 NATIONAL ELECTRICAL.CODE 2008 Edition ARTICLE 450 TRANSFORMERS AND TRANSFORMER VAULTS(INCLUDING SECONDARY TIES t 450.5 Table 450.3(B) Maximum Rating or Setting of Overcurrent Protection for Transformers 600 Volts and Less (as a Percentage of Transformer-Rated Current) Primary Protection Secondary Protection (See Note 2.) Protection Currents of 9 Amperes Currents Less Currents Less Currents of 9 Currents Less Method or More Than 9 Amperes Than 2 Amperes Amperes or More Than 9 Amperes Primary only 125% (See Note L) Not required protection 167% 300% Not required Primary and 250% (See Note 3.) 250% (See Note 3.) 25011v (See Note 3.) 125% (See Note 1.) 167% secondary protection Notes: 1.Where 125 percent of this current does not correspond to a standard rating of a fuse or nonadjustable circuit breaker, a higher rating that does not exceed the next higher standard rating shall be permitted. 2.Where secondary overcurrent protection is required,the secondary overcurrent device shall be permitted to consist of not more than six circuit breakers or six sets of fuses grouped in one location.Where multiple overcurrent devices are utilized, the total of all the device ratings shall not exceed the allowed value of a single overcurrent device. 3.A transformer equipped with coordinated thermal overload protection by the manufacturer and arranged to interrupt the primary current shall be permitted to have primary overcurrent protection rated or set at a current value that is not more than six times the rated current of the transformer for transformers having not more than 6 percent impedance and not more than four times the rated current of the transformer for transformers having more than 6 percent but not more than 10 percent impedance. independent of the main switch and common-trip overcur- (1) Rating. The autotransformer shall have a continuous rent protection for the 3-phase, 4-wire system. neutral-current rating sufficient for the specified ground- fault current. (2) Overcurrent Protection. An overcurrent sensing de- vice shall be provided that will cause the main switch or (2) Overcurrent Protection. Overcurrent protection shall common-trip overcurrent protection referred to in comply with (a) and (b). 450.5(A)(1) to open if the load on the autotransformer (a) Operation and Interrupting Rating. An overcurrent reaches or exceeds 125 percent of its continuous current protective device having an interrupting rating in Compli- per-phase or neutral rating. Delayed tripping for temporary ance with 110.9 and that will open simultaneously all un- overcurrents sensed at the autotransformer overcurrent de- grounded conductors when it operates shall be applied in vice shall be permitted for the purpose of allowing proper the grounding autotransformer branch circuit. operation of branch or feeder protective devices on the (b) Ampere Rating. The overcurrent protection shall be rated or set at a current not exceeding 125 percent of the 4-wire system. autotransformer continuous per-phase current rating or (3) Transformer Fault Sensing. A fault-sensing system 42 percent of the continuous-current rating of any series- that causes the opening of a main switch or common-trip connected devices in the autotransformer neutral connec- overcurrent device for the 3-phase, 4-wire system shall be lion. Delayed tripping for temporary overcurrents to permit provided to guard against single-phasing or internal faults. the proper operation of ground-responsive tripping devices on the main system shall be permitted but shall not exceed FPN: This can be accomplished by the use of two sub- values that would be more than the short-time current rat- tractive-connected donut-type current transformers installed ing of the grounding autotransformer or any series con- to sense and signal when an unbalance occurs in the line current to the autotransformer of 50 percent or more of nected devices in the neutral connection thereto. rated current. Exception: For high-impedance grounded systems covered (4) Rating. The autotransformer shall have a continuous to 250.36, where the maximum ground fault current is de- neutral-current rating that is sufficient to handle the maximum signed to be not more than 10 amperes, and where the grounding autotransformer and the grounding impedance possible neutral unbalanced load current of the 4-wire system, are rated for continuous duty an overtrurrent device rated (B) Ground Reference for Fault Protection Devices. A not more than 20 amperes that will simultaneously open all grounding autotransformer used to make available a specified ungrounded conductors shall be permitted to be installed magnitude of ground-fault current for operation of a ground- on the Tine side of the grounding autotransformer responsive protective device on a 3-phase,3-wire ungrounded (C) Ground Reference for Damping Transitory Over. system shall conform to 450.5(B)(1) and (B)(2). voltages. A grounding autotransformer used to limit 2008 Edition NATIONAL ELEC'T'RICAL CODE 70-337 450.6 ARTICLE 450—TRANSFORMERS AND TRANSFORMER VAULTS (INCLUDING SECONDARY TIES) transitory overvoltages shall be of suitable rating and tors of each phase or neutral shall comply with one of the connected in accordance with 450.5(A)(1), following provisions. {a) Interconnected The conductors shall be intercon- 450.6 Secondary Ties. As used in this article, a secondary nected in order to establish a load supply point, and the Lie is a circuit operating at 600 volts, nominal, or less be- protective device specified in 450.6(A)(3) shall be provided tween phases that connects two power sources or power in each ungrounded tie conductor at this point on both sides supply points, such as the secondaries of two transformers. of the interconnection. The means of interconnection shall The tie shall be permitted to consist of one or more con- have an ampacity not less than the load to be served. ductors per phase or neutral. Conductors connecting the (b) Not Interconnected. The loads shall be connected to secondaries of transformers in accordance with 450.7 shall one or more individual conductors of a paralleled conductor not be considered secondary ties. tie without interconnecting the conductors of each phase or As used in this section, the word transformer means a neutral and without the protection specified in 450.6(A)(3) transformer or a bank of transformers operating as a unit. at load connection points. Where this is done, the tie con- (A) Tie Circuits. Tie circuits shall be provided with over- ductors of each phase or neutral shall have a combined current protection at each end as required in Parts I, 1I, and capacity ampacity of not less than 133 percent of the rated VIII of Article 240. secondary current of the highest rated transformer supply- Under the conditions described in 450.6(A)(1) and ing the secondary tie system, the total load of such taps 450.6(A)(2), the overcurrent protection shall be permitted shall not exceed the rated secondary current of the highest to be in accordance with 450.6(A)(3). rated transformer, and the loads shall be equally divided on each phase and on the individual conductors of each phase (1) Loads at Transformer Supply Points Only.Where all as far as practicable. loads are connected at the transformer supply points at each (5) Tie Circuit Control. Where the operating voltage ex- end of the tie and overcurrent protection is not provided in ceeds 150 volts to ground, secondary ties provided with accordance with Parts 1, 11, and Vill of Article 240, the Iimiters shall have a switch at each end that, when open, rated ampacity of the tie shall not be less than 67 percent of de-energizes the associated tie conductors and limiters.The the rated secondary current of the highest rated transformer current rating of the switch shall not be less than the rated supplying the secondary tie system. current ampacity of the conductors connected to the switch. (2) Loads Connected Between Transformer Supply It shall be capable of interrupting its rated current, and it Points. Where load is connected to the tie at any point shall be constructed so that it will not open under the mag- between transformer supply points and overcurrent protec- netic forces resulting from short-circuit current. tion is not provided in accordance with Parts 1, I1, and VIII of Article 240,the rated ampacity of the tie shall not be less (B) overcurrent Protection for Secondary Connections. Where secondary ties are used, an overcurrent device rated than 100 percent of the rated secondary current of the high- est rated transformer supplying the secondary tie system. or set at not more than 250 percent of the rated secondary current of the transformers shall be provided in the second- Exception: Tie circuits comprised of multiple conductors ary connections of each transformer supplying the tie sys- per phase shall be permitted to be sized and protected in tem. In addition, an automatic circuit breaker actuated by a accordance with 450.6(A)(4). reverse-current relay set to open the circuit at not more than (3) Tie Circuit Protection.Under the conditions described the rated secondary current of the transformer shall be pro- in 450.6(A)(1) and (A)(2), both supply ends of each un- vided in the secondary connection of each transformer. grounded tie conductor shall be equipped with a protective (C) Grounding. Where the secondary tie system is device that opens at a predetermined temperature of the tie grounded, each transformer secondary supplying the tie conductor under short-circuit conditions. This protection system shall be grounded in accordance with the require- shall consist of one of the following: (1) a fusible link cable menns of 250.30 for separately derived systems. connector, terminal, or lug, commonly known as a limiter, each being of a size corresponding with that of the conduc- 450.7 Parallel Operation.Transformers shall be permitted for and of construction and characteristics according to the to be operated in parallel and switched as a unit, provided operating voltage and the type of insulation on the tie con- the overcurrent protection for each transformer meets the ductors or (2) automatic circuit breakers actuated by de- requirements of 450.3(A) for primary and secondary pro- vices having comparable time-current characteristics. tective devices over 600 volts, or 450.3(B) for primary and secondary protective devices 600 volts or less. (4) Interconnection of Phase Conductors Between Transformer Supply Points. Where the tie consists of 450.8 Guarding. Transformers shall be guarded as speci- more than one conductor per phase or neutral, the conduc- fled in 450.8(A) through (D). 70-338 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 450—TRANSFORMERS AND TRANSFORMER VAULTS (INCLUDING SECONDARY TIES) 450.21 (A) Mechanical Protection. Appropriate provisions shall 450.12 Terminal Wiring Space. The minimum wire- be made to minimize the possibility of damage to trans- bending space at fixed, 600-volt and below terminals of formers from external causes where the transformers are transformer line and load connections shall be as required exposed to physical damage. in 312.6. Wiring space for pigtail connections shall con- (B) Case or Enclosure. Dry-type transformers shall be form to Table 314.16(B). provided with a noncombustible moisture-resistant case or 450.13 Accessibility. All transformers and transformer enclosure that provides protection against the accidental vaults shall be readily accessible to qualified personnel for insertion of foreign objects. inspection and maintenance or shall meet the requirements (C) Exposed Energized Parts. Switches or other equip- of 450.13(A) or 450.13(B). ment operating at 600 volts, nominal, or less and serving only equipment within a transformer enclosure shall be per- (A) Open Installations. Dry-type transformers 600 volts, mitted to be installed in the transformer enclosure if acces- sible to qualified persons only. All energized parts shall be structures, shall not be required to be readily accessible. guarded in accordance with 110.27 and 110.34. (B) Hollow Space Installations. Dry-type transformers (D) Voltage Warning. The operating voltage of exposed 600 volts, nominal, or less and not exceeding 50 kVA shall live parts of transformer installations shall be indicated by be permitted in hollow spaces of buildings not permanently signs or visible markings on the equipment or structures. closed in by structure, provided they meet the ventilation requirements of 450.9 and separation from combustible ma- 450.9 Ventilation.The ventilation shall be adequate to dis- terials requirements of 450.21(A).Transformers so installed pose of the transformer full-load losses without creating a shall not be required to be readily accessible. temperature rise that is in excess of the transformer rating. FPN No. 1: See ANSIIIEEE C57.12.00-1993,General Re- II. Specific Provisions Applicable to Different Types of quirenrents for Liquid-Immersed Distribution, Power, and Transformers Reguluting Transfonners,and ANSI/IEEE C57.12.01-1989, General Requirements for Dry-Type Distribution and 450.21 Dry-Type Transformers Installed Indoors. Power Transfonners. FPN No. 2: Additional losses may occur in some trans- (A) Not over 112'/2 kVA. Dry-type transformers installed formers where nonsinusoidal currents are present,resulting indoors and rated 1 12'/ kVA or less shall have a separation in increased heat in the transformer above its rating. See of at least 300 mm (12 in.) from combustible material un- ANSt/IEEE C57.110-1993, Recommended Practice for Es-. less separated from the combustible material by a fire- tablishing Transformer Capability When Supplying Nonsi- resistant, heat-insulated barrier. nusoidal Load Currents, where transformers are utilized with nonlinear loads. Exception: This rule shall not apply to transformers rated Transformers with ventilating openings shall be in- for 600 volts, nominal, or less that are completely enclosed, stalled so that the ventilating openings are not blocked by with or without ventilating openings. walls or other obstructions.The required clearances shall be clearly marked on the transformer. (B) Over 112'/2 kVA. Individual dry-type transformers of more than 1121/z kVA rating shall be installed in a trans- 450.10 Grounding. Where grounded, exposed non— former room of fire-resistant construction. Unless specified current-carrying metal parts of transformer installations, in- otherwise in this article, the term fire resistant means a cluding fences, guards, and so forth, shall be grounded and construction having a minimum fire rating of 1 hour. bonded under the conditions and in the manner specified Exception No. 1: Tran.sfonners with Class 155 or higher for electrical equipment and other exposed metal parts in insulation systems and separated from combustible mate- Parts V, VI, and VII of Article 250. rial by a fire-resistant, heat-insulating barrier or by not less 450.11 Marking. Each transformer shall be provided with than 1.53 m (6 ft) horizontally card 3.7 m (12 ft) vertically. a nameplate giving the name of the manufacturer, rated Exception No. 2: Transformers with Class 155 or higher kilovolt-amperes, frequency, primary and secondary volt- insulation systems and completely enclosed except for ven- age, impedance of transformers 25 kVA and larger, required tilating openings. clearances for transformers with ventilating openings, and FPN: See ANSUASTM E119-1995,Method for Fire Tests the amount and kind of insulating liquid where used. In of Building Construction and Materials, and NFPA 251- addition, the nameplate of each dry-type transformer shall 2006, Standard Methods of Tests of Fire Resistance of include the temperature class for the insulation system. Building Construction and Materials. 2008 Edition NATIONAL ELECTRICAL CODE 70-339 450.22 ARTICLE 450—TRANSFORMERS AND TRANSFORMER VAULTS(INCLUDING SECONDARY TIES) (C) Over 35,000 Volts. Dry-type transformers rated over nonflammable shall be permitted to be installed indoors or 35,000 volts shall be installed in a vault complying with outdoors. Such transformers installed indoors and rated Part I❑ of this article. over 35,000 volts shall be installed in a vault. Such trans- formers installed indoors shall be furnished with a liquid 450.22 Dry-Type Transformers Installed Outdoors. confinement area and a pressure-relief vent.The transform- Dry-type transformers installed outdoors shall have a ers shall be furnished with a means for absorbing any gases weatherproof enclosure, generated by arcing inside the tank, or the pressure-relief Transformers exceeding I121/2 kVA shall not be located vent shall be connected to a chimney or flue that will carry within 300 mm (12 in.) of combustible materials of build- such gases to an environmentally safe area. ings unless the transformer has Class 155 insulation sys- tems or higher and is completely enclosed except for ven- FPN: Safety may be increased if fire hazard analyses are performed for such transformer installations. tilating openings. For the purposes of this section, a nonflammable dielec- 450.23 Less-Flammable Liquid-Insulated Transformers. tric fluid is one that does not have a flash point or fire point Transformers insulated with listed less-flammable liquids and is not flammable in air. that have a fire point of not less than 300°C shall be per- mitted to be installed in accordance with 450.23(A) or 450.25 Askarel-Insulated Transformers Installed In- 450.23(B). doors.Askarel-insulated transformers installed indoors and rated over 25 kVA shall be furnished with a pressure-relief (A) Indoor Installations. Indoor installations shall be per- vent. Where installed in a poorly ventilated place, they milted in accordance with one of the following: shall be furnished with a means for absorbing any gases (1) In Type I or Type II buildings, in areas where all of the generated by arcing inside the case, or the pressure-relief following requirements are met: vent shall be connected to a chimney or flue that carries a. The transformer is rated 35,000 volts or less. such gases outside the building. Askarel-insulated trans- b. No combustible materials are stored, formers rated over 35,000 volts shall be installed in a vault. c. A liquid confinement area is provided. d. The installation complies with all restrictions pro- 450.26 Oil-Insulated Transformers Installed Indoors. vided for in the listing of the liquid. Oil-insulated transformers installed indoors shall be in- (2) With an automatic fire extinguishing system and a liq- stalled in a vault constructed as specified in Part III of this uid confinement area, provided the transformer is rated article. 35,000 volts or less Exception No. 1: Where the total capacity does not exceed (3) In accordance with 450.26 112'/a M, the vault specified in Part III of this article shall be permitted to be constructed of reinforced concrete that is (B) Outdoor Installations. Less-flammable liquid-filled not less than 100 mm (4 in.) thick. transformers shall be permitted to be installed outdoors, attached to, adjacent to, or on the roof of buildings, where Exception No. 2: Where the nominal voltage does not installed in accordance with (1) or (2): exceed 600, a vault shall not be required if suitable ar- (1) For Type I and Type II buildings, the installation shall rangements are made to prevent a transformer oil fire from comply with all restrictions provided for in the listing igniting other materials and the total capacity in one loca- tion does not exceed 10 kVA in a section of the building of the liquid. classified as combustible or 75 kVA where the surrounding FPN: Installations adjacent to combustible material, fire structure is classified as fire-resistant Construction. escapes, or door and window openings may require addi- Exception No. 3: Electric furnace transformers that have tional safeguards such as those listed in 450.27. a total rating not exceeding 75 kVA shall be permitted to be (2) In accordance with 450.27. installed without a vault in a building or room of fire- FPN No. 1: As used in this section, Type I and Type 11 resistant construction, provided suitable arrangements are buildings refers to Type I and Type if building construction made to prevent a transformer oil fire from spreading to as defined in NFPA 220-2006,Standard on Types of Build- other combustible material. ing Construction. Combustible materials refers to those materials not classified as noncombustible or limited- Exception No. 4: A transformer that has a total rating not combustible as defined in NFPA 220-2006. exceeding 75 kVA and a supply voltage of 600 volts or less FPN No. 2: See definition of Listed in Article 100. that is an integral part of charged-particle-accelerating equipment shall be permitted to be installed without a vault 450.24 Nonflammable Fluid-Insulated Transformers. in a building or room of noncombustible or fire-resistant Transformers insulated with a dielectric fluid identified as construction, provided suitable arrangements are made to 70-340 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 450—TRANSFORMERS AND TRANSFORMER VAULTS (INCLUDING SECONDARY TIES) 450.45 prevent a transformer nil file from spreading to other com- 450.42 Walls, Roofs, and Floors. The walls and roofs of bustible material. vaults shall be constructed of materials that have adequate ,Exception No. 5: Transformers shall be permitted to be structural strength for the conditions with a minimum fire installed in a detached building that does not comply with resistance of 3 hours. The floors of vaults in contact with Part III of this article if neither the building nor its contents the earth shall be of concrete that is not less than 100 mm present afire hazard to am other building or property, and (4 in.) thick, but where the vault is constructed with a if the building is used only in supplying electric service and vacant space or other stories below it, the floor shall have the interior is accessible only to qualified persons. adequate structural strength for the load imposed thereon Exception No. 6: Oil-insulated transformers shall he per- and a minimum fire resistance of 3 hours. For the purposes milted to be used without a vault in portable and mobile of this section, studs and wallboard construction shall not surface mitring equipment (such as electric excavators) if be acceptable. each of the following conditions is met: Exception: Where transformers are protected with auto- (a) Provision is made for draining leaking fluid to the intuit sprinkler, water spray, carbon dioxide, or halo, con- ground. .struction of 1-hour rating shall be permitted, (b) Safe egress is provided for personnel. (c) A minimum 6-nun (1/a-in.) steel barrier is provided FPN No. 1: For additional information, see ANSUASTM E 119-1995,Method for Fire Tests of Building Construction for personnel protection. and Materials, and NFPA 251-2006, Standard Methods of 450.27 Oil-Insulated Transformers Installed Outdoors. Tests of Fire Resistance of Building Construction and Combustible material, combustible buildings, and parts of Materials. buildings, fire escapes, and door and window openings FPN No.2: A typical 3-hour construction is 150 mm(6 in.) shall be safeguarded from fires originating in oil-insulated thick reinforced concrete, transformers installed on roofs, attached to or adjacent to a 450.43 Doorways. Vault doorways shall be protected in building or combustible material. accordance with 450.43(A), (B), and (C). In cases where the transformer installation presents a fire hazard, one or more of the following safeguards shall (A) T)rpe of Door.Each doorway leading into a vault from be applied according to the degree of hazard involved: the building interior shall be provided with a tight-fitting (1) Space separations door that has a minimum fire rating of 3 hours.The author- (2) Fire-resistant barriers ity having jurisdiction shall be permitted to require such a (3) Automatic fire suppression systems door for an exterior wall opening where conditions warrant. (4) Enclosures that confine the oil of a ruptured trans- Exception: Where transformers are protected with auto- former lank matic sprinkler, water spray, carbon dioxide, or halon, con- Oil enclosures shall be permitted to consist of fire- struction of 1-hour rating shall be permitted. resistant dikes, curbed areas or basins, or trenches filled FPN: For additional information,see NFPA 80-2007,Stan- with coarse,crushed stone. Oil enclosures shall be provided dard far Fire Doors and Other Opening Protectives. with trapped drains where the exposure and the quantity of oil involved are such that removal of oil is important. (B) Sills. A door sill or curb that is of sufficient height to FPN: For additional information on transformers installed confine the oil from the largest transformer within the vault on poles or structures or under ground,see ANSI C2-2007, shall be provided, and in no case shall the height be less National Electrical Safer• Code. than 100 mm (4 in.). 450.28 Modification of Transformers. When modifica- (C) Locks. Doors shall be equipped with locks, and doors tions are made to a transformer in an existing installation shall be kept locked, access being allowed only to qualified that change the type of the transformer with respect to Part persons. Personnel doors shall swing out and be equipped II of this article, such transformer shall be marked to show with panic bars, pressure plates, or other devices that are the type of insulating liquid installed, and the modified normally latched but open under simple pressure. transformer installation shall comply with the applicable requirements for that type of transformer. 450.45 Ventilation Openings. Where required by 450.9, openings for ventilation shall be provided in accordance 1I1. Transformer Vaults with 450.45(A) through (F). 450.41 Location.Vaults shall be located where they can be (A) Location. Ventilation openings shall be located as far ventilated to the outside air without using flues or ducts as possible from doors, windows, fire escapes,and combus- wherever such an arrangement is practicable, tible material. 2()08 Edition NATIONAL ELECTRICAL CODE 70-341 450.46 ARTICLE 455--PHASE CONVERTERS (B) Arrangement. A vault ventilated by natural circula- 455.2 Definitions. tion of air shall be permitted to have roughly half of the total area of openings required for ventilation in one or Manufactured Phase. The manufactured or derived phase more openings near the floor and the remainder in one or originates at the phase converter and is not solidly con- more openings in the roof or in the sidewalls near the roof, netted to either of the single-phase input conductors. or all of the area required for ventilation shall be permitted Phase Converter.An electrical device that converts single- in one or more openings in or near the roof. phase power to 3-phase electric power, (C) Size. For a vault ventilated by natural circulation of air FPN: Phase converters have characteristics that modify the to an outdoor area, the combined net area of all ventilating starting torque and locked-rotor current of motors served, openings, after deducting the area occupied by screens, and consideration is required in selecting a phase converter gratings, or louvers, shall not be less than 1900 mm'" for a specific load. (3 in.) per kVA of transformer capacity in service, and in Rotary-Phase Converter.A device that consists of a rotary no case shall the net area be less than 0.1 m2 (1 ft`)for any transformer and capacitor panel(s) that permits the opera- capacity under 50 kVA. tion of 3-phase loads from a single-phase supply. (D) Covering. Ventilation openings shall be covered with Static-Phase Converter. A device without rotating parts, durable gratings, screens, or Iouvers, according to the treat- sized for a given 3-phase load to permit operation from a ment required in order to avoid unsafe conditions. single-phase supply. (E) Dampers. All ventilation openings to the indoors shall 455.3 Other Articles. Phase converters shall comply with be provided with automatic closing fire dampers that oper- this article and with the applicable provisions of other Gr- ate in response to a vault fire. Such dampers shall possess a titles of this Code. standard fire rating of not less than 1 err hours. FPN: See ANSI/UL 555-1995,Standard for Fire Dampers. 455.4 Marking. Each phase converter shall be provided with a permanent nameplate indicating the following: (F) Ducts. Ventilating ducts shall be constructed of fire- (1) Manufacturer's name resistant material. (2) Rated input and output voltages 450.46 Drainage. Where practicable, vaults containing (3) Frequency more than 100 kVA transformer capacity shall be provided (4) Rated single-phase input full-load amperes with a drain or other means that will carry off any accumu- (5) Rated minimum and maximum single load in kilovolt- lation of oil or water in the vault unless local conditions amperes (kVA) or horsepower make this impracticable. The floor shall be pitched to the (6) Maximum total load in kilovolt-amperes (kVA) or drain where provided. horsepower 450.47 Water Pipes and Accessories. Any pipe or duct (7) For a rotary-phase converter, 3-phase amperes at full system foreign to the electrical installation shall not enter or load pass through a transformer vault. Piping or other facilities 455.5 Equipment Grounding Connection. A means for provided for vault fire protection, or for transformer cooling, attachment of an equipment grounding conductor termina- shall not be considered foreign to the electrical installation. tion in accordance with 250.$ shall be provided. 450.48 Storage in Vaults. Materials shall not be stored in transformer vaults. 455.6 Conductors. (A) Ampacity. The ampacity of the single-phase supply conductors shall be determined by 455.6(A)(1) or (A)(2). FPN: Single-phase conductors sized to prevent a voltage ARTICLE 455 drop not exceeding 3 percent from the source of supply to Phase Converters the phase converter may help ensure proper starting and operation of motor loads. 1. General (1) Variable Loads. Where the loads to be supplied are variable, the conductor ampacity shall not be less than 455.1 Scope. This article covers the installation and use of 125 percent of the phase converter nameplate single-phase phase converters. input full-load amperes. 70-342 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 455—PHASE CONVERTERS 455.23 (2) Fixed Loads. Where the phase converter supplies spe- ampere rating not less than 250 percent of the sum of the cific fixed loads, and the conductor ampacity is less than following: 125 percent of the phase converter nameplate single-phase (l) Full-load, 3-phase current ratings of the motors input full-load amperes, the conductors shall have an am- (2) Other loads served pacity not less than 250 percent of the sum of the full-load, 3-phase current rating of the motors and other loads served (2) Horsepower Rated Disconnect. The disconnecting where the input and output voltages of the phase converter are means shall be a switch with a horsepower rating. The identical. Where the input and output voltages of the phase equivalent locked rotor current of the horsepower rating of converter are different, the current as determined by this sec- the switch shall not be less than 200 percent of the sum of [ion shall be multiplied by the ratio of output to input voltage. the following: (1) Nonmotor loads (B) Manufactured Phase Marking. The manufactured (2) The 3-phase, locked-rotor current of the largest motor phase conductors shall be identified in all accessible loca- as determined from Table 430.251(B) tions with a distinctive marking.The marking shall be con- sistent throughout the system and premises. (3) The full-load current of all other 3-phase motors oper- ating at the same time 455.7 Overcurrent Protection. The single-phase supply (D) Voltage Ratios. The calculations in 455.8(C) shall ap- conductors and phase converter shall be protected from ply directly where the input and output voltages of the overcurrent by 455.7(A) or(B). Where the required fuse or phase converter are identical. Where the input and output nonadjustable circuit breaker rating or settings of adjustable voltages of the phase converter are different, the current shall circuit breakers do not correspond to a standard rating or be multiplied by the ratio of the output to input voltage. setting, a higher rating or setting that does not exceed the next higher standard rating shall be permitted. 455.9 Connection of Single-Phase Loads. Where single- phase loads are connected on the load side of a phase con- (A) Variable Loads. Where the loads to be supplied are verter,they shall not be connected to the manufactured phase. variable, overcurrent protection shall be set at not more than 125 percent of the phase converter nameplate single- 455.10 Terminal Housings. A terminal housing in accor- phase input full-load amperes, dance with the provisions of 430.12 shall be provided on a (B) Fixed Loads. Where the phase converter supplies spe- phase converter. cific fixed loads and the conductors are sized in accordance with 455.6(A)(2), the conductors shall be protected in accor- 11. Specific Provisions Applicable to Different Types of dance with their ampacity. The overcurrent protection deter- Phase Converters mined from this section shall not exceed 125 percent of the 455.20 Disconnecting Means. The single-phase discon- phase converter nameplate single-phase input amperes. necting means for the input of a static phase converter shall be penmitted to serve as the disconnecting means for the 455.8 Disconnecting Means. Means shall be provided to phase converter and a single load if the load is within sight disconnect simultaneously all ungrounded single-phase of the disconnecting means. supply conductors to the phase converter. 455.21 Start-Up. Power to the utilization equipment shall (A) Location. The disconnecting means shall be readily not be supplied anti] the rotary-phase converter has been accessible and located in sight from the phase converter. started. (B) Type.The disconnecting means shall be a switch rated 455.22 Power interruption. Utilization equipment lup- in horsepower, a circuit breaker, or a molded-case switch. plied by a rotary-phase converter shall be controlled in such Where only nonmotor loads are served, an ampere-rated a manner that power to the equipment will be disconnected switch shall be permitted. in the event of a power interruption. (C) Rating.The ampere rating of the disconnecting means FPN: Magnetic motor starters, magnetic contactors, and shall not be less than 115 percent of the rated maximum similar devices,with manual or time delay restarting for the single-phase input full-load amperes or, for specific fixed load, provide restarting after power interruption. loads, shall be permitted to be selected from 455.8(C)(1) or 455.23 Capacitors. Capacitors that are not an integral part of the rotary-phase conversion system but are installed for a (1) Current Rated Disconnect. The disconnecting means motor load shall be connected to the line side of that motor shall be a circuit breaker or molded-case switch with an overload protective device. 2008 Edition NATIONAL ELECTRICAL CODE 70-343 460.1 ARTICLE 460—CAPACITORS the motor circuit conductors and in no case less than ART'TCLI 460 135 percent of the rated current of the capacitor. Capacitors (B) Overcurrent Protection. An overcurrent device shall be provided in each ungrounded conductor for each capaci- tor bank. The rating or setting of the overcurrent device 460.1 Scope. This article covers the installation of capaci- shall be as low as practicable. tors on electrical circuits. Surge capacitors or capacitors included as a component Exception: A separate overcurrent device shall not be re- part of other apparatus and conforming with the requirements quired for a capacitor connected on the load side of a of such apparatus are excluded from these requirements. motor overload protective device. This article also covers the installation of capacitors in (C) Disconnecting Means. A disconnecting means shall hazardous(classified) locations as modified by Articles 501 be provided in each ungrounded conductor for each capaci- through 503. for bank and shall meet the following requirements: 460.2 Enclosing and Guarding. (1) The disconnecting means shall open all ungrounded g g conductors simultaneously. (A) Containing More Than 11 L (3 gal) of Flammable (2) The disconnecting means shall be permitted to discon- Liquid.Capacitors containing more than 11 L(3 gal)of flam- nect the capacitor from the line as a regular operating mable liquid shall be enclosed in vaults or outdoor fenced procedure. enclosures complying with Article 110, Part III. This limit (3) The rating of the disconnecting means shall not be less shall apply to any single unit in an installation of capacitors. than 135 percent of the rated current of the capacitor. Exception: A separate disconnecting means shall not be (B) Accidental Contact. Where capacitors are accessible reyuired where a capacitor is connected on the lead side of to unauthorized and unqualified persons, they shall be en- a motor controller closed, located, or guarded so that persons cannot come into accidental contact or bring conducting materials into 460.9 Rating or Setting of Motor Overload Device. accidental contact with exposed energized parts, terminals, Where a motor installation includes a capacitor connected or buses associated with them. However, no additional on the load side of the motor overload device, the rating or guarding is required for enclosures accessible only to au- setting of the motor overload device shall be based on the thorized and qualified persons. improved power factor of the motor circuit. The effect of the capacitor shall be disregarded in de- termining the motor circuit conductor rating in accordance I. 600 Volts, Nominal, and Under with 430.22. 460.6 Discharge of Stored Energy. Capacitors shall be 460.10 Grounding. Capacitor cases shall be connected to provided with a means of discharging stored energy. the equipment grounding conductor. (A) Time of Discharge. The residual voltage of a capaci- Exception: Capacitor cases shall not be connected to the for shall be reduced to 50 volts, nominal, or less within 1 equipment grounding conductor where the capacitor units minute after the capacitor is disconnected from the source are .supported on a structure designed to operate at other of supply. than ground potential. (B) Means of Discharge. The discharge circuit shall be 460.12 Marking. Each capacitor shall be provided with a either permanently connected to the terminals of the capaci- nameplate giving the name of the manufacturer, rated volt- tor or capacitor bank or provided with automatic means of age, frequency, kitovar or amperes, number of phases, and, connecting it to the terminals of the capacitor bank on re- if filled with a combustible liquid, the volume of liquid. moval of voltage from the line. Manual means of switching Where filled with a nonflammable liquid, the nameplate or connecting the discharge circuit shall not be used. shall so state. The nameplate shall also indicate whether a capacitor has a discharge device inside the case. 460.8 Conductors. II. Over 600 Volts, Nominal (A) Ampacity. The ampacity of capacitor circuit conduc- 460.24 Switching. tors shall not be less than 135 percent of the rated current of the capacitor. The ampacity of conductors that connect a (A) Load Current. Group-operated switches shall be capacitor to the terminals of a motor or to motor circuit used for capacitor switching and shall be capable of the conductors shall not be less than one-third the ampacity of following: 70-344 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 474—RESISTORS AND REACTORS 470.3 (1) Carrying continuously not less than 135 percent of the 460.26 Identification. Each capacitor shall be provided rated current of the capacitor installation with a permanent nameplate giving the manufacturer's (2) Interrupting the maximum continuous load current of name, rated voltage, frequency, kilovar or amperes, number each capacitor, capacitor bank, or capacitor installation of phases,and the volume of liquid identified as flammable, that will be switched as a unit if such is the case, (3) Withstanding the maximum inrush current, including contributions from adjacent capacitor installations 460.27 Grounding. Capacitor cases Shaill be connected to the equipment grounding conductor. If the capacitor neutral (4) Carrying currents due to faults on capacitor side of point is connected to a grounding electrode conductor, the switch connection shall be made in accordance with Part HI of (B) Isolation. Article 250. (1) General. A means shall be installed to isolate from all Exception: Capacitor cases shall not be connected to the sources of voltage each capacitor, capacitor bank, or ca- equipment grounding conductor where the capacitor units pacitor installation that will be removed from service as a are supported on a structure designed to operate at other unit. The isolating means shall provide a visible gap in the than ground potential. electrical circuit adequate for the operating voltage. 460.28 Means for Discharge. (2) Isolating or Disconnecting Switches with No Inter- rupting Rating. Isolating or disconnecting switches (with (A) Means to Reduce the Residual Voltage. A means no interrupting, rating) shall be interlocked with the load- shall be provided to reduce the residual voltage of a capaci- interrupting device or shall be provided with prominently for to 50 volts or less within 5 minutes after the capacitor is displayed caution signs in accordance with 490.22 to pre- disconnected from the source of supply. vent switching load current. (B) Connection to Terminals. A discharge circuit shall be (C) Additional Requirements for Series Capacitors.The either permanently connected to the terminals of the capaci- proper switching sequence shall be ensured by use of one for or provided with automatic means of connecting it to of the following: the terminals of the capacitor bank after disconnection of the capacitor from the source of supply. The windings of (1) Mechanically sequenced isolating and bypass switches motors, transformers, or other equipment directly con- (2) Interlocks nected to capacitors without a switch or overcurrent device (3) Switching procedure prominently displayed at the interposed shall meet the requirements of 460.28(A). switching location 460.25 Overcurrent Protection. (A) Provided to Detect and Interrupt Fault Current. A ARTICLE 470 means shall be provided to detect and interrupt fault current Resistors and Reactors likely to cause dangerous pressure within an individual ca- pacitor. (B) Single Pole or Multipole Devices.Single-pole or mul- 1. 600 Volts, Nominal, and Under tipole devices shall be permitted for this purpose. 470.1 Scope.This article covers the installation of separate resistors and reactors on electrical circuits. (C) Protected Individually or in Groups. Capacitors shall be permitted to be protected individually or in groups. Exception: Resistors and reactors that are component parts of other apparatus. (D) Protective Devices Rated or Adjusted. Protective de- This article also covers the installation of resistors and vices for capacitors or capacitor equipment shall be rated or reactors in hazardous (classified) locations as modified by adjusted to operate within the limits of the safe zone for individual capacitors. If the protective devices are rated or Articles 501 through 504. adjusted to operate within the limits for Zone 1 or Zone 2, 470,2 Location. Resistors and reactors shall not be placed the capacitors shall he enclosed or isolated. where exposed to physical damage. In no event shall the rating or adjustment of the protec- tive devices exceed the maximum limit of Zone 2. 470.3 Space Separation. A thermal barrier shall be re- FPN: For definitions of Safe 2one, Zone 1, and Zane 2, see quired if the space between the resistors and reactors and ANSIAEEE 18-1992, Shunt Power Capacitors. any combustible material is less than 305 mm (12 in.). 2008 Edition NATIONAL EL£CCRICAI.CODE 70-345 470.4 ARTICLE 480--STORAGE BATTERIES 470.4 Conductor Insulation. Insulated conductors used 480.2 Definitions. for connections between resistance elements and controllers shall be suitable for an operating temperature of not less Nominal Battery Voltage. The voltage calculated on the than 90°C (194°F). basis of 2 volts per cell for the lead-acid type and 1.2 volts per cell for the alkali type. Exception: Other conductor insulations shall be permitted far motor starring service. Sealed Cell or Battery. A sealed cell or battery is one that has no provision for the addition of water or electrolyte or for external measurement of electrolyte specific gravity. IL Over 600 Volts, Nominal The individual cells shall be permitted to contain a venting 470.18 General. arrangement as described in 480.10(B). Storage Battery. A battery comprised of one or more re- (A) Protected Against Physical Damage. Resistors and chargeable cells of the lead-acid, nickel-cadmium, or other reactors shall be protected against physical damage. rechargeable electrochemical types. (B) Isolated by Enclosure or Elevation. Resistors and re- 480.3 Wiring and Equipment Supplied from Batteries. actors shall be isolated by enclosure or elevation to protect Wiring and equipment supplied from storage batteries shall personnel from accidental contact with energized parts. be subject to the applicable.provisions of this Code apply- (C) Combustible Materials. Resistors and reactors shall ing to wiring and equipment operating at the same voltage, not be installed in close enough proximity to combustible ma- unless otherwise permitted by 480.4. terials to constitute a fire hazard and shall have a clearance of 480.4 Overcurrent Protection for Prime Movers. Over- not less than 305 mm (12 in.) from combustible materiaLs. current protection shall not be required for conductors from (D) Clearances. Clearances from resistors and reactors to a battery rated less than 50 volts if the battery provides grounded surfaces shall be adequate for the voltage involved. power for starting, ignition, or control of prime movers. Section 300.3 shall not apply to these conductors. FPN: See Article 490. 480.5 Disconnecting Means. A disconnecting means shall (E) Temperature Rise from Induced Circulating Cur- be provided for all ungrounded conductors derived from a rents. Metallic enclosures of reactors and adjacent metal Stationary battery System over 30 volts. A disconnecting parts shall be installed so that the temperature rise from means shall be readily accessible and located within sight induced circulating currents is not hazardous to personnel of the battery system. or does not constitute a fire hazard. 480.6 insulation of Batteries Not Over 250 Volts. This 470.19 Grounding. Resistor and reactor cases or enclosures section shall apply to storage batteries having cells con- shall be connected to the equipment grounding conductor. nected so as to operate at a nominal battery voltage of not Exception: Resistor or reactor cases or enclosures sup- over 250 volts. paned on a structure designed to operate at other than (A) Vented Lead-Acid Batteries.Cells and multicompart- ground potential shall not be connected to the equipment ment batteries with covers sealed to containers of noncon- grounding conductor ductive, heat-resistant material shall not require additional insulating support. 470.20 Oil-Filled Reactors. Installation of oil-filled reac- tors, in addition to the above requirements, shall comply (B) Vented Alkaline-Type Batteries. Cells with covers with applicable requirements of Article 450. seated to jars of nonconductive,heat-resistant material shall require no additional insulation support. Cells in jars of conductive material shall be installed in trays of noncon- ductive material with not more than 20 cells (24 volts, ARTICLE 484 nominal) in the series circuit in any one tray. Storage Batteries (C) Rubber Jars. Cells in rubber or composition contain- ers shall require no additional insulating support where the total nominal voltage of all cells in series does not exceed 480.1 Scope. The provisions of this article shall apply to 150 volts. Where the total voltage exceeds I50 volts, bat- all stationary installations of storage batteries. teries shall be sectionalized into groups of 150 volts or less, 70-346 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 490—EQUIPMENT,OVER 600 VOLTS,NOMINAL 490.21 and each group shall have the individual cells installed in the cell due to ignition of gases within the cell by an exter- trays or on racks. nal spark or flame under normal operating conditions. (D) Sealed Cells or Batteries. Sealed cells and multicom- (B) Sealed Cells. Sealed battery or cells shall be equipped partment sealed batteries constructed of nonconductive, with a pressure-release vent to prevent excessive accumu- heat-resistant material shall not require additional insulat- lation of gas pressure, or the battery or cell shall be Be- ing support. Batteries constructed of a conducting container signed to prevent scatter of cell parts in event of a cell shall have insulating support if a voltage is present between explosion. the container and ground. 480.7 Insulation of Batteries of over 250 Volts. The pro- visions of 480.6 shall apply to storage batteries having the cells connected so as to operate at a nominal voltage ex- ARTICLE 490 ceeding 250 volts, and, in addition, the provisions of this Equipment, Over 600 Volts, Nominal section shall also apply to such batteries. Cells shall be installed in groups having a total nominal voltage of not over 250 volts. Insulation, which can be air, shall be pro- I. General vided between groups and shall have a minimum separation 490.1 Scope. This article covers the general requirements between live battery parts of opposite polarity of 50 mm for equipment operating at more than 600 volts, nominal. (2 in.) for battery voltages not exceeding 600 volts. FPN No. 1: See NFPA 70E-2(X)4, Standard for Electrical 480.8 Racks and Trays. Racks and trays shall comply Safety in the Workplace, for electrical safety requirements with 480.8(A) and (B). for employee workplaces. FPN No. 2: For further information on hazard signs and (A) Racks. Racks, as required in this article, are rigid labels,see ANSI 2535-4, Product Signs and Safer Labels. frames designed to support cells or trays. They shall he substantial and be made of one of the following: 490.2 Definition. (1) Metal, treated so as to be resistant to deteriorating ac- High Voltage. For the purposes of this article, more than tion by the electrolyte and provided with nonconduct- 600 volts, nominal. ing members directly supporting the cells or with con- tinuous insulating material other than paint on 490.3 Oil-Filled Equipment. Installation of electrical conducting members equipment, other than transformers covered in Article 450, (2) Other construction such as fiberglass or other suitable containing more than 38 L (10 gal) of flammable oil per nonconductive materials unit shall meet the requirements of Parts 11 and III of Ar- (B) Trays. Trays are frames, such as crates or shallow ticle 450. boxes usually of wood or other nonconductive material, constructed or treated so as to be resistant to deteriorating Ill. Equipment—Specific Provisions action by the electrolyte. 490.21 Circuit-Interrupting Devices. 480.9 Battery Locations. Battery locations shall conform (A) Circuit Breakers. to 480.9(A), (B), and (C). (A) Ventilation. Provisions shall be made for sufficient (1) Location. diffusion and ventilation of the gases from the battery to (a) Circuit breakers installed indoors shall be mounted prevent the accumulation of an explosive mixture. either in metal-enclosed units or fire-resistant cell-mounted units, or they shall be permitted to be open-mounted in (B) Live Parts. Guarding of live parts shall comply with locations accessible to qualified persons only. 110.27• (b) Circuit breakers used to control oil-filled transform- (C) Working Space. Working space about the battery sys- ers shall either be located outside the transformer vault or tems shall comply with )10.26. Working clearance shall be be capable of operation from outside the vault. measured from the edge of the battery rack. (c) Oil circuit breakers shall be arranged or located so that adjacent readily combustible structures or materials are 480.10 Vents. safeguarded in an approved manner. (A) Vented Cells. Each vented cell shall be equipped with (2) Operating Characteristics.Circuit breakers shall have a flame arrester that is designed to prevent destruction of the following equipment or operating characteristics: 2008 Edition NATIONAL ELECTRICAL CODE 70-347 490.21 ARTICLE 490—EQUIPMENT,OVER 600 VOLTS,NOMINAL (1) An accessible mechanical or other approved means for (3) Voltage Rating.The maximum voltage rating of power manual tripping, independent of control power fuses shall not be less than the maximum circuit voltage. (2) Be release free (trip free) Fuses having a minimum recommended operating voltage (3) If capable of being opened or closed manually while shall not be applied below this voltage. energized, main contacts that operate independently of (4) Identification of Fuse Mountings and Fuse Units. the speed of the manual operation Fuse mountings and fuse units shall have permanent and (4) A mechanical position indicator at the circuit breaker to legible nameplates showing the manufacturer's type or des- show the open or closed position of the main contacts ignation, continuous current rating, interrupting current rat- (5) A means of indicating the open and closed position of ing, and maximum voltage rating. the breaker at the point(s) from which they may be (5) Fuses. Fuses that expel flame in opening the circuit operated shall be designed or arranged so that they function properly (3) Nameplate. A circuit breaker shall have a permanent without hazard to persons or property. and legible nameplate showing manufacturer's name or (6) Fuseholders. Fuseholders shall be designed or in- trademark, manufacturer's type or identification number, stalled so that they are de-energized while a fuse is being continuous current rating, interrupting rating in megavolt- replaced. amperes (MVA) or amperes, and maximum voltage rating. Modification of a circuit breaker affecting its rating(s) shall Exception: Fuses and firsehvlders designed to permit fuse replacement by qualified be accompanied by an appropriate change of nameplate ified persons using equipment designed information. for the purpose without de-energizing the fuseholder shall be permitted. (4) Rating.Circuit breakers shall have the following ratings: (7) High-Voltage Fuses. Metal-enclosed switchgear and (1) The continuous current rating of a circuit breaker shall substations that utilize high-voltage fuses shall be provided not be less than the maximum continuous current with a gang-operated disconnecting switch. Isolation of the through the circuit breaker. fuses from the circuit shall be provided by either connect- (2) The interrupting rating of a circuit breaker shall not be ing a switch between the source and the fuses or providing less than the maximum fault current the circuit breaker roll-out switch and fuse-type construction.The switch shall be will be required to interrupt, including contributions of the load-interrupter type,unless mechanically or electrically from all connected sources of energy. interlocked with a load-interrupting device arranged to reduce (3) The closing rating of a circuit breaker shall not be less the load to the interrupting capability of the switch. than the maximum asymmetrical fault current into Exception: More than one switch shall be permitted as the which the circuit breaker can be closed. disconnecting means for one set of fuses where the switches (4) The momentary rating of a circuit breaker shall not be are installed to provide connection to more than one set of less than the maximum asymmetrical fault current at supply conductors. The switches shall be mechanically or the point of installation. electrically interlocked to permit access to the fuses only (5) The rated maximum voltage of a circuit breaker shall when all switches are open. A conspicuous sign shall be not be less than the maximum circuit voltage. placed at the fuses identifying the presence of more than one source. (B) Power Fuses and Fuseholders. (C) Distribution Cutouts and Fuse Links — Expulsion (1) Use. Where fuses are used to protect conductors and ')'PC. equipment, a fuse shall be placed in each ungrounded con- (1) Installation. Cutouts shall be located so that they may ductor. Two power fuses shall be permitted to be used in be readily and safely operated and re-fused, and so that the parallel to protect the same load if both fuses have identical exhaust of the fuses does not endanger persons. Distribu- ratings and both fuses are installed in an identified common lion cutouts shall not be used indoors, underground, or in mounting with electrical connections that divide the current metal enclosures. equally. Power fuses of the vented type shall not be used indoors, underground, or in metal enclosures unless identi- (2) Operation. Where fused cutouts are not suitable to fied for the use. interrupt the circuit manually while carrying full load, an approved means shall be installed to interrupt the entire (2) Interrupting Rating. The interrupting rating of power load. Unless the fused cutouts are interlocked with the fuses shall not be less than the maximum fault current the switch to prevent opening of the cutouts under load, a con- fuse is required to interrupt, including contributions from spicuous sign shall be placed at such cutouts identifying all connected sources of energy. that they shall not be operated under load. 70-348 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 490—EQUIPMENT.OVER 600 VOLTS,NOMINAL 490.22 (3) Interrupting Rating. The interrupting rating of distri- (E) Load Interrupters. Load-interrupter switches shall be bution cutouts shall not be less than the maximum fault permitted if suitable fuses or circuit breakers are used in current the cutout is required to interrupt, including contri- conjunction with these devices to interrupt fault currents. butions from all connected sources of energy. Where these devices are used in combination, they shall be coordinated electrically so that they will safely withstand (4) Voltage Rating. The maximum voltage rating of cut- the effects of closing, carrying, or interrupting all possible outs shall not be less than the maximum circuit voltage. currents up to the assigned maximum short-circuit rating. (5) Identification. Distribution cutouts shall have an their Where more than one switch is installed with intercon- body, door, or fuse tube a permanent and legible nameplate nected load terminals to provide for alternate connection to or identification showing the manufacturer's type or desig- different supply conductors, each switch shall be provided nation, continuous current rating, maximum voltage rating, with a conspicuous sign identifying this hazard. and interrupting rating. (1) Continuous Current Rating. The continuous current (6) Fuse Links. Fuse links shall have a permanent and rating of interrupter switches shall equal or exceed the legible identification showing continuous current rating and maximum continuous current at the point of installation. type. (2) Voltage Rating. The maximum voltage rating of inter- (7) Structure Mounted Outdoors. The height of cutouts rupter switches shall equal or exceed the maximum circuit mounted outdoors on structures shall provide safe clearance voltage. between lowest energized parts (open or closed position) (3) Identification. Interrupter switches shall have a perma- and standing surfaces, in accordance with 110.34(E), nent and legible nameplate including the following infor- mation: manufacturer's type or designation,continuous cur- (D) Oil-Filled Cutouts. rent rating, interrupting current rating, fault closing rating, (1) Continuous Current Rating. The continuous current maximum voltage rating. rating of oil-filled cutouts shall not be less than the maxi- (4) Switching of Conductors. The switching mechanism mum continuous current through the cutout. shall be arranged to be operated from a location where the (2) Interrupting Rating. The interrupting rating of oil- operator is not exposed to energized parts and shall be filled cutouts shall not be less than the maximum fault arranged to open all ungrounded conductors of the circuit current the ail-filled cutout is required to interrupt, includ- simultaneously with one operation. Switches shall be ar- ing contributions from all connected sources of energy. ranged to be locked in the open position. Metal-enclosed switches shall be operable from outside the enclosure. (3) Voltage Rating. The maximum voltage rating of oil- filled cutouts shall not be less than the maximum circuit (5) Stored Energy for Opening.The stored-energy opera- voltage. for shall be permitted to be left in the uncharged position after the switch has been closed if a single movement of the (4) Fault Closing Rating. Oil-filled cutouts shall have a operating handle charges the operator and opens the switch. fault closing rating not less than the maximum asymmetri- cal fault current that can occur at the cutout location, unless (6) Supply Terminals. The supply terminals of fused in- suitable interlocks or operating procedures preclude the terrupter switches shall be installed at the top of the switch possibility of closing into a fault. enclosure, or, if the terminals are located elsewhere, the equipment shall have barriers installed so as to prevent (5) Identification. Oil-filled cutouts shall have a perma- persons from accidentally contacting energized parts or nent and legible nameplate showing the rated continuous dropping tools or fuses into energized parts. current,rated maximum voltage, and rated interrupting cur- rent. 490.22 Isolating Means. Means shall be provided to com- pletely isolate an item of equipment. The use of isolating (6) Fuse Links. Fuse links shall have a permanent and switches shall not be required where there are other ways of legible identification showing the rated continuous current. de-energizing the equipment for inspection and repairs, (7) Location. Cutouts shall be located so that they are such as draw-out-type metal-enclosed switchgear units and readily and safely accessible for re-fusing, with the top of removable truck panels. the cutout not over 1.5 m (5 ft) above the floor or platform. Isolating switches not interlocked with an approved circuit-interrupting device shall be provided with a sign (8) Enclosure.Suitable barriers or enclosures shall be pro- warning against opening them under load. vided to prevent contact with nonshielded cables or ener- A fuseholder and fuse, designed for the purpose, shall gized parts of oil-filled cutouts. be permitted as an isolating switch. 2008 Edition NATIONAL ELECTRICAL CODE 70.349 490.23 ARTICLE 490—EQUIPMENT,OVER 000 VOLTS,NOMINAL 'fable 490.24 Minimum Clearance of Live Parts Minimum Clearance of Live Parts Phase-to-Phase Phase-to-Ground Nominal Impulse Withstand, Voltage B.I.L(kV) Indoors Outdoors Indoors Outdoors Rating (kV) Indoors Outdoors mm in, mm in. mm in. mm in. 2.4--4.16 60 95 115 4.5 180 7 80 3.0 155 6 7.2 75 95 140 5.5 180 7 105 4.0 155 6 13.8 95 110 195 7.5 305 12 130 5.0 180 7 14.4 110 110 230 9.0 305 12 170 6.5 180 7 23 125 150 270 10.5 385 15 190 7.5 255 10 34.5 150 150 320 12.5 385 15 245 9.5 255 10 200 200 460 18.0 460 18 335 13.0 335 13 46 — 200 — — 460 t8 — — 335 13 — 250 — — 535 21 — — 435 17 69 — 250 — — 535 21 — — 435 17 — 350 — — 790 31 — 635 25 115 550 — — 1350 53 — 1070 42 138 — 550 — — 1350 53 — 1070 42 -- 650 _a — 1605 63 — 1270 50 161 — 650 — — i605 63 — — 1270 50 — 750 — — 1830 72 — -- 1475 58 230 — 750 — — 1830 72 — 1475 58 — 900 — — 2265 89 — 1805 71 — 1050 — — 2670 105 — — 2110 83 Note:The values given are the minimum clearance for rigid part,and bare conductors under favorable service conditions.They shall be increased for conductor movement or under unfavorable service conditions or wherever space limitations permit. The selection of the associated impulse withstand voltage for a particular system voltage is determined by the characteristics of the surge protective equipment. 490.23 Voltage Regulators.Proper switching sequence for cludes metal-enclosed power switchgear assemblies that regulators shall be ensured by use of one of the following: form a part of unit substations, power centers, or similar (1) Mechanically sequenced regulator bypass switch(es) equipment. (2) Mechanical interlocks 490.31 Arrangement of Devices in Assemblies. Arrange- (3) Switching procedure prominently displayed at the ment of devices in assemblies shall be such that individual switching location components can safely perform their intended function without adversely affecting the safe operation of other com- 490.24 Minimum Space Separation. In field-fabricated ponents in the assembly. installations, the minimum air separation between bare live conductors and between such conductors and adjacent 490.32 Guarding of High-Voltage Energized Parts grounded surfaces shall not be less than the values given in Within a Compartment. Where access for other than vi- Table 490.24. These values shall not apply to interior sual inspection is required to a compartment that contains portions or exterior terminals of equipment designed, energized high-voltage parts, barriers shall be provided to manufactured, and tested in accordance with accepted prevent accidental contact by persons, tools, or other equip- national standards. ment with energized parts. Exposed live parts shall only be permitted in compartments accessible to qualified persons. III. Equipment— Metal-Enclosed Power Switchgear Fuses and fuseholders designed to enable future replace- and Industrial Control Assemblies ment without de-energizing the fuseholder shall only be permitted for use by qualified persons. 490.30 General. This part covers assemblies of metal- enclosed power switchgear and industrial control, including 490.33 Guarding of Low-Voltage Energized Parts but not limited to switches, interrupting devices and their Within a Compartment. Energized bare parts mounted control, metering, protection and regulating equipment, on doors shall be guarded where the door must be where an integral part of the assembly, with associated in- opened for maintenance of equipment or removal of terconnections and supporting structures. This part also in- draw-out equipment. 70-350 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 490—EQUIPMENT, OVER 6(X)VOLTS.NOMINAL 490.45 490.34 Clearance for Cable Conductors Entering En- 490.41 Location of Devices, closure. The unobstructed space opposite terminals or op- posite raceways or cables entering a switchgear or control (A) Control and Instrument Transfer Switch Handles assembly shall be adequate for the type of conductor and or Pushbuttons. Control and instrument transfer switch method of termination. handles or pushbuttons other than those covered in 490.41(B) shall be in a readily accessible location at an 490.35 Accessibility of Energized Parts. elevation of not over 2.0 m (78 in.). (A) High-Voltage Equipment, Doors that would provide Exception: Operating handles requiring more than 23 kg unqualified persons access to high-voltage energized parts (50 lb) of force shall be located no higher than I.7 in in.) in either the open or closed position. shall be locked, {B} Infrequently Operated Devices. Operating handles (B} Low-Voltage Control Equipment. Low-voltage con- for infrequently operated devices, such as drawout fuses, tral equipment, relays, motors, and the like shall not be fused potential or control transformers and their primary installed in compartments with exposed high-voltage ener- disconnects,and bus transfer switches,shall be permitted to gized parts or high-voltage wiring unless either of the fol- be located where they are safely operable and serviceable lowing conditions is met: from a portable platform. (1) The access means is interlocked with the high-voltage switch or disconnecting means to prevent the access 490.42 Interlocks — Interrupter Switches. Interrupter means from being opened or removed. switches equipped with stored energy mechanisms shall (2) The high-voltage switch or disconnecting means is in have mechanical interlocks to prevent access to the switch the isolating position. compartment unless the stored energy mechanism is in the discharged or blocked position. (C) High-Voltage Instruments or Control Transformers and Space Heaters. High-voltage instrument or control 490.43 Stored Energy for Opening.The stored energy op- transformers and space heaters shall be permitted to be erator shall be permitted to be left in the uncharged position installed in the high-voltage compartment without access after the switch has been closed if a Single movement of the restrictions beyond those that apply to the high-voltage operating handle charges the operator and opens the switch. compartment generally. 490.44 Fused Interrupter Switches. 490.36 Grounding. Frames of switchgear and control as- (A) Supply Terminals. The supply terminals of fused in- semblies shall be connected to an equipment grounding terrupter switches shall be installed at the top of the switch conductor or, where permitted, the grounded conductor. enclosure or, if the terminals are located elsewhere, the equipment shall have barriers installed so as to prevent 490.37 Grounding of Devices.The metal cases or frames, persons from accidentally contacting energized parts or or both, such as instruments, relays, meters, and instrument dropping tools or fuses into energized parts. and control transformers, located in or on switchgear or control, shall be connected to an equipment grounding con- (B) Backfeed. Where fuses can be energized by backfeed, duetor or, where permitted, the grounded conductor. a sign shall be placed on the enclosure door identifying this hazard. 490.38 Door Stops and Cover Plates. External hinged doors or covers shall be provided with stops to hold them in (C) Switching Mechanism. The switching mechanism the open position. Cover plates intended to be removed for shall be arranged to be operated from a location outside the inspection of energized parts or wiring shall be equipped enclosure where the operator is not exposed to energized with lifting handles and shall not exceed 1.1 m` (12 ft') in parts and shall be arranged to open all ungrounded conduc- area or 27 kg (60 lb) in weight, unless they are hinged and tors of the circuit simultaneously with one operation. bolted or locked. Switches shall be capable of being locked in the open po- sition.The provisions for locking shall remain in place with 490.39 Gas Discharge from Interrupting Devices. Gas or without the lock installed. discharged during operating of interrupting devices shall be 490.45 Circuit Breakers— Interlocks. directed so as not to endanger personnel. (A) Circuit Breakers. Circuit breakers equipped with 490.40 Inspection Windows. Windows intended for in- stored energy mechanisms shall be designed to prevent the spection of disconnecting switches or other devices shall be release of the stored energy unless the mechanism has been of suitable transparent material, fully charged. 2008 Edition NATIONAL ELECTRICAL CODE 70-351 490.46 ARTICLE 490---EQUIPMENT,OVER 600 VOLTS,NOMINAL (B) Mechanical Interlocks. Mechanical interlocks shall locked-rotor protection and shall be permitted to be exter- be provided in the housing to prevent the complete with- nal to the equipment. drawal of the circuit breaker from the housing when the stored energy mechanism is in the fully charged position, 490.53 Enclosures. All energized switching and control unless a suitable device is provided to block the closing parts shall be enclosed in grounded metal cabinets or en- function of the circuit breaker before complete withdrawal. closures. These cabinets or enclosures shall be marked "DANGER—HIGH VOLTAGE—KEEP OUT" and shall 490.46 Circuit Breaker Locking.Circuit breakers shall be be locked so that only authorized and qualified persons can capable of being locked in the open position or,if they are enter. Circuit breakers and protective equipment shall have installed in a drawout mechanism, that mechanism shall be the operating means projecting through the metal cabinet or capable of being Iocked in such a position that the mecha- enclosure so these units can be reset without opening nism cannot be moved into the connected position.In either locked doors. With doors closed, reasonable safe access for case,the provision for locking shall remain in place with or normal operation of these units shall be provided. without the lock. 490.54 Collector Rings. The collector ring assemblies on 490.47 Metal-Enclosed and Metal-Clad Service Equip- revolving-type machines (shovels, draglines, etc.) shall be ment. Metal-enclosed and metal-clad switchgear installed guarded to prevent accidental contact with energized parts as high-voltage service equipment shall include a ground by personnel on or off the machine. bus for the connection of service cable shields and to fa- cilitate the attachment of safety grounds for personnel pro- 490.55 Power Cable Connections to Mobile Machines. tection. This bus shall be extended into the compartment A metallic enclosure shall be provided on the mobile ma- where the service conductors are terminated. chine for enclosing the terminals of the power cable. The enclosure shall include terminal connections to the machine frame for the equipment grounding conductor. Ungrounded IV. Mobile and Portable Equipment conductors shall be attached to insulators or be terminated 490.51 General. in approved high-voltage cable couplers (which include equipment grounding conductor connectors)of proper volt- (A) Covered. The provisions of this part shall apply to age and ampere rating. The method of cable termination installations and use of high-voltage power distribution and used shall prevent any strain or pull on the cable from utilization equipment that is portable, mobile, or both, such stressing the electrical connections. The enclosure shall as substations and switch houses mounted on skids, trailers, have provision for locking so that only authorized and or cars; mobile shovels; draglines; cranes; hoists; drills; qualified persons may open it and shall be marked as fol- dredges; compressors; pumps; conveyors; underground ex- lows: cavators; and the like. DANGER— HIGH VOLTAGE — KEEP OUT. (B) Other Requirements. The requirements of this part shall be additional to, or amendatory of, those prescribed in 490.56 High-Voltage Portable Cable for Main Power Articles 100 through 725 of this Code. Special attention Supply. Flexible high-voltage cable supplying power to shall be paid to Article 250. portable or mobile equipment shall comply with Article 250 and Article 400, Part III. (C) Protection. Adequate enclosures, guarding, or both, shall be provided to protect portable and mobile equipment V. Electrode-Type Boilers from physical damage. 490.70 General. The provisions of this part shall apply to (D) Disconnecting Means. Disconnecting means shall be boilers operating over 600 volts, nominal, in which heat is installed for mobile and portable high-voltage equipment generated by the passage of current between electrodes according to the requirements of Part VIII of Article 230 through the liquid being heated. and shall disconnect all ungrounded conductors. 490.71 Electrical Supply System. Electrode-type boilers 490.52 Overcurrent Protection. Motors driving single or shall be supplied only from a 3-phase, 4-wire solidly multiple do generators supplying a system operating on a grounded wye system, or from isolating transformers ar- cyclic load basis do not require overload protection, pro- ranged to provide such a system. Control circuit voltages vided that the thermal rating of the ac drive motor cannot shall not exceed 150 volts, shall be supplied from a be exceeded under any operating condition. The branch- grounded system, and shall have the controls in the un- circuit protective device(s) shall provide short-circuit and grounded conductor. 70-352 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 490—EQUIPMENT,OVER 500 VOLTS,NOMINAL 490.74 490.72 Branch-Circuit Requirements. (1) Connected to the pressure vessel containing the elec- trodes (A) Rating. Each boiler shall be supplied from an indi- (2) Insulated for not less than 600 volts vidual branch circuit rated not less than 100 percent of the total load. (3) Have not less than the ampacity of the largest un- grounded branch-circuit conductor (B) Common-Trip Fault-Interrupting Device. The cir- (4) Installed with the ungrounded conductors in the same cuit shall be protected by a 3-phase, common-trip fault- raceway, cable, or cable tray, or, where installed as interrupting device, which shall be permitted to automati- open conductors, in close proximity to the ungrounded cally reclose the circuit upon removal of an overload conductors condition but shall not reclose after a fault condition. (5) Not used for any other circuit (C) Phase-Fault Protection. Phase-fault protection shall 490.73 Pressure and Temperature Limit Control. Each be provided in each phase, consisting of a separate phase- boiler shall be equipped with a means to limit the maxi- overcurrent relay connected to a separate current trans- mum temperature, pressure, or both, by directly or indi- former in the phase. rectly interrupting all current flow through the electrodes. Such means shall be in addition to the temperature, pres- (D) Ground Current Detection. Means shall be provided sure, or both, regulating systems and pressure relief or for detection of the sum of the neutral conductor and equip- safety valves. ment grounding conductor currents and shall trip the circuit-interrupting device if the sum of those currents ex- 490.74 Grounding. All exposed non—current-carrying ceeds the greater of 5 amperes or 71/2 percent of the boiler metal parts of the boiler and associated exposed metal full-load current for 10 seconds or exceeds an instantaneous structures or equipment shall be bonded to the pressure value of 25 percent of the boiler full-load current. vessel or to the neutral conductor to which the vessel is connected in accordance with 250.102, except the ampacity (E) Grounded Neutral Conductor. The grounded neutral of the bonding jumper shall not be less than the ampacity of conductor shall be as follows: the neutral conductor. 2008 Edition NATIONAL ELECTRICAL CODE 70--353 CHAPTER 5 ARTICLE 500—HAZARDOUS (CLASSIFIED)LOCATIONS.CLASSES [,II,AND III, DIVISIONS I AND 2 Chapter 5 Special Occupancies FPN: Associated nonincendive field wiring apparatus has ARTICLE 500 designated associated nonincendive field wiring apparatus connections for nonincendive field wiring apparatus and Hazardous (Classified') Locations, may also have connections for other electrical apparatus. Classes T, II, and IZI, Divisions I and 2 Combustible Gas Detection System. A protection technique utilizing stationary gas detectors in industrial establishments. FPN: Rules that are followed by a reference in brackets contain text that has been extracted from NFPA 497-2004, Control Drawing. A drawing or other document provided Recommended Practice for the Classification of Flammable by the manufacturer of the intrinsically safe or associated ap- Liquids, Gases, or Vapors and of Hazardous (Classified) paratus,or of the nonincendive field wiring apparatus or asso- Locations for Electrical Installations in Chemical Process ciated nonincendive field wiring apparatus, that details the al- Areas,and NFPA 499-2004,Recommended Practice for the Classification of Combustible Dusts and of Hazardous lowed interconnections between the intrinsically safe and (Classified) Locations for Electrical Installation in Chemi- associated apparatus or between the nonincendive field wiring ctrl Process Areas. Only editorial changes were made to the apparatus or associated nonincendive field wiring apparatus. extracted text to make it consistent with this Code. Dust-Ignitionproof. Equipment enclosed in a manner that 500.1 Scope — Articles 500 Through 504. Articles 500 excludes dusts and does not permit arcs, sparks, or heat through 504 cover the requirements for electrical and elec- otherwise generated or liberated inside of the enclosure to tronic equipment and wiring for all voltages in Class 1, cause ignition of exterior accumulations or atmospheric Divisions 1 and 2; Class I1, Divisions 1 and 2; and Class suspensions of a specified dust on or in the vicinity of the III, Divisions 1 and 2 locations where fire or explosion enclosure, hazards may exist due to flammable gases, flammable liquid-produced vapors, combustible liquid produced va- FPN: For further information on dust-ignitionproof enclo- pors, combustible dusts, or ignitible fibers/liyings. sures,see Type 9 enclosure in ANSI/NEMA 250-1991,En- closures for Electrical Equipment, and ANSI/UL 1203- FPN No. 1: The unique hazards associated with explo- 1994, Explosionproof and Dust-lgnitionprvof Electrical lives,pyrotechnics,and blasting agents are not addressed in Equipment for Hazardous(Classified) Locations. this article. Dusttight. Enclosures constructed so that dust will not en- FPN No. 2: For the requirements for electrical and elec- ter under specified test conditions, tronic equipment and wiring for all voltages in Class 1, Zone 0,Zone 1,and Zone 2 hazardous(classified)locations FPN: See ANSIASA-12.12.01-2000,Nonincendive Electri- where fire or explosion hazards may exist due to flammable cal Equipment for Use in Class I and 11, Division 2, and gases or vapors or flammable liquids, refer to Article 505. Class III, Divisions I and 2 Hazardous (Classified) FPN No. 3: For the requirements for electrical and elect Locations. tronic equipment and wiring for all voltages in Zone 20, Zone 21, and Zone 22 hazardous (classified) locations Electrical and Electronic Equipment. Materials, fittings, where fire or explosion hazards may exist due to combus- devices, appliances, and the like that are part of, or in tible dusts or ignitible fibers/flyings, refer to Article 50& connection with, an electrical installation. 500.2 Definitions. For purposes of Articles 500 through FPN: Portable or transportable equipment having self- 504 and Articles 510 through 516, the following definitions contained power supplies, such as battery-operated equip- apply ment, could potentially become an ignition source in haz- ardous (classified) locations. See ISA-RP12.12.03-2002, Associated Nonincendive Field Wiring Apparatus. Ap- Portable Electronic Products Suitable for Use in Class 1 paratus in which the circuits are not necessarily nonincen- and 11, Division 2, Class I Zone 2 and Class 111, Division I dive themselves but that affect the energy in nonincendive and 2 Hazardous(Classified) Locations. field wiring circuits and are relied upon to maintain nonin- Explosionproof Apparatus. Apparatus enclosed in a case cendive energy levels. Associated nonincendive field wir- that is capable of withstanding an explosion of a specified ing apparatus may be either of the following: gas or vapor that may occur within it and of preventing the (1) Electrical apparatus that has an alternative type of pro- ignition of a specified gas or vapor surrounding the encto- tection for use in the appropriate hazardous (classified) sure by sparks, flashes, or explosion of the gas or vapor location within, and that operates at such an external temperature (2) Electrical apparatus not so protected that shall not be that a surrounding flammable atmosphere will not be ig- used in a hazardous (classified) location nited thereby. 70-354 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 500-HAZARDOUS (CLASSIFIED)LOCATIONS,CLASSES 1, 11, AND 1II, DIVISIONS I AND 2 500.4 FPN: For further information, see ANSUUL 1203-1994, l and 11, Division 2, and Class III, Divisions I and 2 Hatt Explosion-Proof and Dust-Ignition-Proof Electrical Equip- ardous(Classified) Lxc•ations. meat for Use in Hazardous (Classified) Locations. Oil Immersion. Electrical equipment immersed in a pro- Hermetically Sealed. Equipment sealed against the en- tective liquid in such a way that an explosive atmosphere trance of an external atmosphere where the seal is made by that may be above the liquid or outside the enclosure can- fusion, for example, soldering, brazing, welding, or the fu- not be ignited. sion of glass to metal. FPN: For further information, see ANSIIUL 698-1995,In- FPN: For further information, see ANSUISA-12.12.01- dustrial Control Equipment for Use in Hazardous (Class•i- 2000,Nonincendive Electrical Equipment fur Use in Class .tied)Locations. I and 11, Division 2, and Class 111, Division I and 2 Haz- Purged and Pressurized, The process of(1) purging. su P- aniut (Classified) Lcatirnas. plying an enclosure with a protective gas at a sufficient flow Nonincendive Circuit. A circuit, other than field wiring, in and positive pressure to reduce the concentration of any which any arc or thermal effect produced under intended flammable gas or vapor initially present to an acceptable operating conditions of the equipment is not capable, under level; and (2) pressurization, supplying an enclosure with a specified test conditions, of igniting the flammable gas-air, protective gas with or without continuous flow at sufficient vapor-air, or dust-air mixture. pressure to prevent the entrance of a flammable gas or vapor, a combustible dust, or an ignitible fiber. FPN: Conditions are described in ANSUISA-12.12.01- 2000,Nonincendive Electrical Equipment for Use in Class FPN: For further information, see ANSI/NFPA 496-2003, 1 and 11, Division 2, and Class 111, Divisions I and 2 Ha::- Purges! and Pressurized Enclosures for Electrical ardour(Classified) Locations. Equipment. Nonincendive Component, A component having contacts Unclassified Locations. Locations determined to be neither for making or breaking an incendive circuit and the con- Class 1, Division 1; Class I, Division 2; Class I, Zone 0; tasting mechanism is constructed so that the component is Class I,Zone I; Class I, Zone 2; Class I1, Division l; Class incapable of igniting the specified flammable gas-air or II, Division 2; Class II1, Division 1; Class III, Division 2; vapor-air mixture. The housing of a nonincendive compo- Zone 20; Zone 21; Zone 22; or any combination thereof. nent is not intended to exclude the flammable atmosphere or contain an explosion. 500.3 Other Articles. Except as modified in Articles 500 through 504, all other applicable rules contained in this FPN: For further information, see ANSUISA-12.12.01- Code shall apply to electrical equipment and wiring in- 2000,Nonincendive Electrical Equipment for Use in Class stalled in hazardous (classified) locations. 1 and A Division 2, and Class 111, Divisions 1 and 2 Haz- ardous(Classified) Locations. 500.4 General. Nonincendive Equipment. Equipment having electrical/ (A) Documentation. All areas designated as hazardous electronic circuitry that is incapable, under normal operating (classified) locations shall be properly documented. This conditions, of causing ignition of a specified flammable gas- documentation shall be available to those authorized to de- air, vapor-air, or dust--air mixture due to arcing or thermal sign, install, inspect, maintain, or operate electrical equip- means' ment at the location. FPN: For further information, see ANSUISA-12.12.01- (B) Reference Standards. Important information relat- 2000,Nonincendive Electrical Equipment for Use in Class I and 11, Division 2, and Class 111, Divisions 1 and 2 Haz- ardous (Classified) Luc•ations, publications. Nonincendive Field Wiring. Wiring that enters or leaves FPN No. l: It is important that the authority having juris- diction be familiar with recorded industrial experience as an equipment enclosure and, under normal operating con- well as with the standards of the National Fire Protection As- sociation (NFPA), the American Petroleum Institute (API), thermal effects, of igniting the flammable gas-air, vapor- and the instrumentation, Systems, and Automation Society air, or dust-air mixture. Normal operation includes open- (ISA)that may he of use in the classification of various loca- tions, the determination of adequate ventilation, and the pro- tection shorting, or grounding the field wiring. against static electricity and lightning hazards. p Nonincendive Field Wiring Apparatus. Apparatus in- FPN No. 2: For further information on the classification of tended to be connected to nonincendive field wiring. locations,see NFPA 30-2006,Flammable and Combustible Liquids Code, NFPA 32-2007, Standard for DrYclecnuing FPN: For further information see ANSI/ISA-12.12.01- Plants;NFPA 33-2007,Standard for SprapApplication U.s- 2000,Nonincendive Electrical Equipment for Use in Class ing Flammable or Combustible Materials; NFPA 34-2007, 2008 Edition NATIONAL.ELECTRICAL CODE 70-355 5005 ARTICLE 500—HAZARDOUS(CLASSIFIED)LOCATIONS,CLASSES I,A,AND III,DIVISIONS I AND 2 Standard for Dipping and Coating Processes Using Flam- Rooms and areas containing ammonia refrigeration sys- mable or Combustible Liquids; NFPA 35-2005, Standard tems that are equipped with adequate mechanical ventila- for the Manufacture of Organic Coatings; NFPA 36-2004, tion may be classified as "unclassified" locations. Standard for Solvent Extraction Plants; NFPA 45-2004, Standard on Fire Protection for Laboratories Using Chemi- FPN: For further information regarding classification and cals; NFPA 55-2005, Standard for the Storage, Use, and ventilation of areas involving ammonia, see ANStIASHRAE Handling of Compressed Gases and Cryogenic Fluids in 15-1994, Safety Code for Mechanical Refrigeration, and Portable and Stationary Containers. Cylinders, and Tanks; ANSI/CGA G2.1-1989, Safety Requirements for the Storage NFPA 58-2008, Liquefied Petroleum Gas Code; NFPA 59- and Handling of Anhydrous Ammonia. 2004. Utility LP-Gas Plant Code;NFPA 497-2004,Recom- mended Practice for the Classification of Flammable Liq- uids. Gases, or Vapors and of Hazardous (Classified) (B) Class I Locations. Class I locations are those in which Locations for Electrical Installations in Chemical Process flammable gases, flammable liquid-produced vapors, or Areas, NFPA 499-2004, Recommended Practice for the combustible liquid produced vapors are or may be present Classification of Combustible Dusts and of Hazardous in the air in quantities sufficient to produce explosive or (Classified)Locations for Electrical Installations in Chemi- ignitible mixtures. Class I locations shall include those cal Process Areas;NFPA 820-2008,Standard for Fire Pro- tection in Wastewater Treatment and Collection Facilities; specified in 500.5(B}(l) and (B){2). ANSI/API RP500-1997, Recommended Practice for Clas- sification of Locations of Electrical Installations at Petro- leum Facilities Classified as Class 1, Division I and Divi- location sion 2; iSA-12.10-1988,Area Classificarion in Hazardous (1) In which ignitible concentrations of flammable gases, (Classified) Dust Locations. flammable liquid produced vapors, or combustible FPN No. 3: For further information on protection against liquid–produced vapors can exist under normal operat- static electricity and lightning hazards in hazardous (classi- ing conditions, or fied)locations,see NFPA 77-2007,Recommended Practice on Static Electricity; NFPA 780-2008,Standard for the In- stallation of Lightning Protection Systems; and API RP gases, flammable liquid-produced vapors, or combus- 2003-1998, Protection Against Ignitions Arising Out of tible liquids above their flash points may exist fre- Static Lightning and Stray Currents. quently because of repair or maintenance operations or FPN No. 4: For further information on ventilation, see because of leakage, or NFPA 30-2008, Flammable and Combustible Liquids Code; (3) In which breakdown or faulty operation of equipment and API RP 500-1997,Recommended Practice for Classifiea- or processes might release ignitible concentrations of tion of Locations for Electrical Installations at Petroleum Fa- flammable gases, flammable liquid-produced vapors, cilities Classified as Class I, Division I and Division 2. or combustible liquid-produced vapors and might also FPN No. 5: For further information on electrical systems cause simultaneous failure of electrical equipment in for hazardous(classified)locations on offshore oil-and gas- such a way as to directly cause the electrical equipment producing platforms, see ANSI/API RP 14F-1999, Recom- to become a source of ignition. mended Practice for Design and Installation of Electrical Systems for Fixed and Floating Offshore Petroleum Facili- ties for Unclassified and Class 1, Division 1 and Division 2 FPN No. l: This classification usually includes the foIlow- Locations. ing locations: (1) Where volatile flammable liquids or liquefied flam- 500.5 Classifications of Locations. mable gases are transferred from one container to an- other (A) Classifications of Locations. Locations shall be clas- (2) Interiors of spray booths and areas in the vicinity of spraying and painting operations where volatile flam- sified depending on the properties of the flammable gas, mable solvents are used flammable liquid-produced vapor, combustible-liquid pro- (3) Locations containing open tanks or vats of volatile duced vapors, combustible dusts, or fibers/flyings that may flammable liquids be present,and the likelihood that a flammable or combustible (4) Drying rooms or compartments for the evaporation of concentration or quantity is present. Where pyrophoric mate- flammable solvents (5) Locations containing fat- and oil-extraction equip- rials are the only materials used or handled, these locations ment using volatile flammable solvents shall not be classified. Each room, secfion, or area shall be (6) Portions of cleaning and dyeing plants where flam- considered individually in determining its classification. mable liquids are used (7) Gas generator rooms and other portions of gas manu- FPN: Through the exercise of ingenuity in the layout of facturing plants where flammable gas may escape electrical installations for hazardous (classified) locations, (8) Inadequately ventilated pump rooms for flammable it is frequently possible to locate much of the equipment in gas or for volatile flammable liquids a reduced level of classification or in an unclassified loca- (9) The interiors of refrigerators and freezers in which tion and, thus, to reduce the amount of special equipment volatile flammable materials are stored in open, required. lightly stoppered, or easily ruptured containers 70-356 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 5I)0—HAZARDOUS (CLASSIFIED) LOCATIONS,CLASSES 1, 11,AND 111, DIVISIONS I AND 2 500.5 (10) All other locations where ignitible concentrations of area involved, and the record of the industry or business flammable vapors or gases are likely to occur in the with respect to explosions or fires are all factors that merit course of normal operations consideration in determining the classification and extent of FPN No. 2: In some Division I locations,ignitible concen- each location. trations or flammable gases or vapors may be present con- FPN No. 2: Piping without valves, cheeks, meters, and tinuously or for long periods of time. Examples include the similar devices would not ordinarily introduce a hazardous following: condition even though used for flammable liquids or gases. Depending on factors such as the quantity and size of the (1) The inside of inadequately vented enclosures contain- containers and ventilation, locations used for the storage of ing instruments normally venting flammable gases or flammable liquids or liquefied or compressed gases in vapors to the interior of the enclosure sealed containers may be considered either hazardous(clas- (_) The inside of vented tanks containing volatile flam- sified)or unclassified locations. See NFPA 30-2008, Mam- mable liquids mahle and Combustible Liquids Code, and NFPA 58-2008, (3) The area between the inner and outer roof sections of a Liquefied Petroleum Gas Code. floating rox)f tank containing volatile flammable fluids (4) Inadequately ventilated areas within spraying or coat- ing operations using volatile flammable fluids (C) Class 11 Locations. Class Il locations are those that (5) The interior of an exhaust duct that is used to vent are hazardous because of the presence of combustible dust. ignitible concentrations of gases or vapors Class Ii locations shall include those specified in Experience has demonstrated the prudence of avoiding the 500.5(C)(1) and (C)(2). installation of instrumentation or other electrical equipment in these particular areas altogether or where it cannot be avoided (1) Class II, Division 1. A Class II, Division 1 location is because it is essential to the process and other locations are not a location feasible [see 500.5(A), FPNI using electrical equipment or in- (l) In which combustible dust is in the air under normal strumentation approved for the specific application or consist- operating conditions in quantities sufficient to produce ing of intrinsically safe systems as described in Article 504, explosive or ignitible mixtures, or (2) Class 1, Division 2. A Class 1, Division 2 location is a (2) Where mechanical failure or abnormal operation of location machinery or equipment might cause such explosive or (1) In which volatile flammable gases, flammable liquid– ignitible mixtures to be produced, and might also pro- produced vapors, or combustible liquid–produced va- vide a source of ignition through simultaneous failure pors are handled, processed, or used, but in which the of electrical equipment, through operation of protection liquids, vapors, or gases will normally be confined devices, or from other causes, or within closed containers or closed systems from which (3) In which Group E combustible dusts may be present in they can escape only in case of accidental rupture or quantities sufficient to be hazardous. breakdown of such containers or systems or in case of abnormal operation of equipment, or FPN: Dusts containing magnesium or aluminum are par- ticularly hazardous, and the use of extreme precaution is (2) In which ignitible concentrations of flammable gases, necessary to avoid ignition and explosion. flammable liquid–produced vapors, or combustible liquid–produced vapors are normally prevented by (2) Class 11, Division 2. A Class 11, Division 2 location is positive mechanical ventilation and which might be- a location come hazardous through failure or abnormal operation (1) In which combustible dust due to abnormal operations of the ventilating equipment, or may be present in the air in quantities sufficient to (3) That is adjacent to a Class 1, Division 1 location, and to produce explosive or ignitible mixtures; or which ignitible concentrations of flammable gases, (2) Where combustible dust accumulations are present but flammable liquid-produced vapors, or combustible are normally insufficient to interfere with the normal liquid produced vapors above their flash points might operation of electrical equipment or other apparatus, occasionally be communicated unless such communi- but could as a result of infrequent malfunctioning of cation is prevented by adequate positive-pressure ven- handling or processing equipment become suspended tilation from a source of clean air and effective safe- in the air; or guards against ventilation failure are provided. (3) In which combustible dust accumulations on, in, or in the vicinity of the electrical equipment could be suffi- FPN No. I: This classification usually includes locations or cient to interfere with the safe dissipation of heat from where volatile flammable liquids or flammable gases or P vapors are used but that, in the judgment of the authority electrical equipment, or could be ignitible by abnormal having jurisdiction, would become hazardous only in case operation or failure of electrical equipment. of an accident or of some unusual operating condition.The quantity of flammable material that might escape in case of FPN No. 1: The quantity of combustible dust that may be accident, the adequacy of ventilating equipment, the total present and the adequacy of dust removal systems are factors 2008 Edition NATIONAL ELECTRICAL CODE 70-357 500.6 ARTICLE 500—HAZARDOUS (CLASSIFIED)LOCATIONS,CLASSES 1,II,AND 11I, DIVISIONS 1 AND 2 that merit consideration in determining the classification and FPN No. 3: Certain chemical atmospheres may have char- may result in an unclassified area. acteristics that require safeguards beyond those required for FPN any of the Class I groups. Carbon disulfide is one of these man No. 2: Where products such as seed are handled t a of chemicals because of its low ignition temperature (90°C) manner that produces low quantities of dust, the amount and the small joint clearance permitted to arrest its flame. dust deposited may not warrant classification. (D) Class III Locations. Class III locations are those that (1) Group A. Acetylene. [497:3.3.5.1.1 are hazardous because of the presence of easily ignitible (2) Group B. Flammable gas, flammable liquid-produced fibers or materials producing combustible flyings are vapor, or combustible liquid-produced vapor mixed with handled, manufactured, or used, but in which such air that may burn or explode, having either a maximum fibers/flyings are not likely to be in suspension in the air in experimental safe gap (MESG) value less than or equal to quantities sufficient to produce ignitible mixtures. Class 11I 0.45 mm or a minimum igniting current ratio (MIC ratio) locations shall include those specified in 500.5(D)(1) and less than or equal to 0.40. [497:3.3.5.1.2] (D)(2). FPN: A typical Class 1, Group B material is hydrogen. (1) Class III, Division 1. A Class III, Division I location Exception No. 1: Group D equipment shall be permitted to is a location in which easily ignitible fibeWffyings are be used for atmospheres containing butadiene,provided all handled, manufactured, or used. conduit runs into explosionproof equipment are provided FPN No. 1: Such locations usually include some parts of with explosionproof seals installed within 450 mm (18 in.) rayon, cotton, and other textile mills; combustible of the enclosure. fibers/flyings manufacturing and processing plants; cotton Exception No. 2: Group C equipment shall be permitted to gins and cotton-seed mills; flax-processing plants; clothing manufacturing plants, woodworking plants; and establish- be used for atmospheres containing allyl glycidyl ether, ments and industries involving similar hazardous processes n-butyl glycidyl ether, ethylene oxide, propylene oxide, and or conditions. acrolein, provided all conduit runs into explosionproof FPN No. 2: Easily ignitible fibers/flyings include rayon, equipment are provided with explosionproof seals installed cotton (including cotton linters and cotton waste), sisal or within 450 nrm (18 in.) of the enclosure. henequen, istle,jute, hemp, tow, cocoa fiber, oakum, baled waste kapok, Spanish moss, excelsior, and other materials (3) Group C. Flammable gas, flammable liquid–produced of similar nature. vapor, or combustible liquid--produced vapor mixed with (2) Class III, Division 2. A Class III, Division 2 location air that may burn or explode, having either a maximum is a location in which easily ignitible fibers/flyings are experimental safe gap (MESG) value greater than 0.45 mm stored or handled other than in the process of manufacture, and less than or equal to 0.75 mm, or a minimum igniting current ratio (MIC ratio) greater than 0.40 and less than or 500.6 Material Groups. For purposes of testing, approval, equal to 0.80. [497:3.3.5.1.3] and area classification, various air mixtures (not oxygen- FPN: A typical Class 1, Group C material is ethylene. enriched) shall be grouped in accordance with 500.6(A) and (B). (4) Group D. Flammable gas, flammable liquid–produced vapor, or combustible liquid–produced vapor mixed with Exception: Equipment identified far a specific gas, vapor, air that may burn or explode, having either a maximum or dust. experimental safe gap (MESG)value greater than 0.75 mm FPN: This grouping is based on the characteristics of the or a minimum igniting current ratio (MIC ratio) greater materials. Facilities are available for testing and identifying than 0.80. [497:3.3.5.1.4] equipment for use in the various atmospheric groups. FPN No. 1: Atypical Class I,Group D material is propane. (A) Class I Group Classifications. Class I groups shall be FPN No. 2: For classification of areas involving ammonia atmospheres,see ANSIIASHRAE 15-1994,Safety Cade far according to 500.6(A)(1} through (A)(4), Mechanical Refrigeration, and ANSVCGA G2.1-I989, FPN No. is FPN Nos. 2 and 3 apply to 500.6(A). Safety Requirements for the Storage and Handling of An- hydrous Ammonia. FPN No.2: The explosion characteristics of air mixtures of gases or vapors vary with the specific material involved. (B) Class II Group Classifications. Class II groups shall For Class I locations, Groups A, B, C, and D, the classifi- cation involves determinations of maximum explosion be in accordance with 500.6(B)(1} through (B){3). pressure and maximum safe clearance between parts of a clamped joint in an enclosure.It is necessary,therefore,that (1) Group E. Atmospheres containing combustible metal equipment be identified not only for class but also for the dusts, including aluminum, magnesium, and their commer- specific group of the gas or vapor that will be present. cial alloys, or other combustible dusts whose particle size, 70-358 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 500—HAZARDOUS (CLASSIFIED)LOCATIONS,CLASSES 1, 11,AND III, DIVISIONS 1 AND 2 500.7 abrasiveness, and conductivity present similar hazards in (D) Purged and Pressurized. This protection technique the use of electrical equipment. [499:3.3.4.1] shall be permitted for equipment in any hazardous (classi- FPN: Certain meta[ dusts may have characteristics that re- fied) location for which it is identified. quire safeguards beyond those required for atmospheres containing the dusts of aluminum, magnesium, and their (E) Intrinsic Safety. This protection technique shall be commercial alloys. For example, zirconium, thorium, and permitted for equipment in Class I, Division 1 or 2; or uranium dusts have extremely low ignition temperatures las Class I1, Division 1 or 2; or Class III, Division 1 or 2 low as 20°C (68°F)1 and minimum ignition energies lower locations. The provisions of Articles 501 through 503 and than any material classified in any of the Class I or Class II Articles 510 through 516 shall not be considered applicable groups. to such installations, except as required by Article 504, and (2) Group F.Atmospheres containing combustible carbon- installation of intrinsically safe apparatus and wiring shall aceous dusts that have more than S percent total entrapped be in accordance with the requirements of Article 504. volatiles (see ASTM D 3175-02, Standard Test Method for Volatile Matter in the Atullrsis Sample for Coal and Coke, (F} Nonincendive Circuit. This protection technique shall coal and coke dusts) or that have been sensitized by be permitted for equipment in Class I, Division 2; Class II, other materials so that they present an explosion hazard. Division 2; or Class III, Division 1 or 2 locations. Coal, carbon black, charcoal, and coke dusts are examples (G) Nonincendive Equipment. This protection technique of carbonaceous dusts. [499:3.3.4.2] shall be permitted for equipment in Class I, Division 2; (3) Group G. Atmospheres containing combustible dusts Class 1I, Division 2; or Class III, Division 1 or 2 locations, not included in Group E or F, including flour, grain, wood, plastic, and chemicals. (K) Nonincendive Component. This protection technique shall be permitted for equipment in Class I, Division 2; FPN No. 1: For additional information on group classifea- Class 1I, Division 2; or Class III, Division I or 2 locations. tion of Class II materials, see NFPA 499-2004, Recom- mended Practice for the Classification of Combustible (I) Oil Immersion. This protection technique shall be per- Dusts and of Hazardous (Classified)Locations for Electri- mitted for current-interrupting contacts in Class I, Division cal Installations in Chemical Process Areas. 2 locations as described in 501.115(B)(1)(2). FPN No.2: The explosion characteristics of air mixtures of dust vary with the materials involved. For Class Il loca- (J) Hermetically Sealed. This protection technique shall tions, Groups E. F, and G, the classification involves the be permitted for equipment in Class I, Division 2; Class 1I, tightness of the joints of assembly and shaft openings to prevent the entrance of dust in the dust-ign iti onproof enclo- sure, the blanketing effect of layers of dust on the equip- ment that may cause overheating,and the ignition tempera- (K) Combustible Gas Detection System. A combustible ture of the dust.It is necessary,therefore,that equipment be gas detection system shall be permitted as a means of pro- identified not only for the class but also for the specific tection in industrial establishments with restricted public group of dust that will be present. access and where the conditions of maintenance and super- FPN No. 3: Certain dusts may require additional precau- vision ensure that only qualified persons service the instal- tions due to chemical phenomena that can result in the lation. Where such a system is installed, equipment speci- generation of ignitible gases. See ANSI C2-2007,National fied in 500.7(K)(1), (K)(2), or (K)(3) shall be permitted. Electrical Safenv Code, Section 127A, Coal Handling The type of detection equipment, its listing, installation Areas. location(s), alarm and shutdown criteria, and calibration 500.7 Protection Techniques. Section 500.7(A) through frequency shall be documented when combustible gas de- (L)shall he acceptable protection techniques for electrical and tectors are used as a protection technique. electronic equipment in hazardous (classified) locations. FPN No. l: For further information, see ANSUISA- 12.13.01-2003 (IEC 61779-1 through -5 Mad), Perfor- (A) Explosionproof Apparatus.This protection technique mance Requirements, Combustible Gas Detectors, and shall be permitted for equipment in Class I, Division 1 or 2 ANSIML 2075, Gas and Vapor Detectors and Sensors. locations. FPN No. 2: For further information, see ANSIIAPI RP 500,Recommended Practice for Classification of Locations (B) Dust Ignitionproof. This protection technique shall be for Electrical Installations at Petroleum Facilities Classi- permitted for equipment in Class II, Division 1 or 2 locations. fled as Class 1, Division I or Division 2. (C) Dusttight. This protection technique shall be permit- FPN No. 3: For further information, see ANSUISA-RP 12.13.02-2003 (EEC 61779-6 Mod), Installation, Opera- ted for equipment in Class II, Division 2 or Class III, Di- Lion, and Maintenance of Combustible Gas Detection vision I or 2 locations. Instruments. 2008 Edition NATIONAL ELECTRICAL CODE 70-359 500.8 ARTICLE 500—HAZARDOUS(CLASSIFIED)LOCATIONS,CLASSES 1,11,AND 11I,DIVISIONS 1 AND 2 (1) Inadequate Ventilation. In a Class I, Division 1 loca- FPN: Additional documentation for equipment may ing tion that is so classified due to inadequate ventilation, elec- elude certificates demonstrating compliance with applicable trical equipment suitable for Class 1, Division 2 locations equipment standards, indicating special conditions of use, shall be permitted. Combustible gas detection equipment and other pertinent information, shall be listed for Class 1, Division I, for the appropriate (g) Approval for Class and Properties. material group, and for the detection of the specific gas or vapor to be encountered. (1) Equipment shall be identified not only for the class of location but also for the explosive,combustible, or ignitible (2) Interior of a Building.In a building located in,or with properties of the specific gas, vapor, dust, or fiibers/flyings an opening into, a Class 1, Division 2 location where the that will be present. In addition,Class I equipment shall not interior does not contain a source of flammable gas or va- have any exposed surface that operates at a temperature in por, electrical equipment for unclassified locations shall be excess of the ignition temperature of the specific gas or permitted. Combustible gas detection equipment Shall be vapor. Class II equipment shall not have an external tem- listed for Class I, Division I or Class 1,Division 2,for the perature higher than that specified in 500.8(D)(2). Class III appropriate material group, and for the detection of the equipment shall not exceed the maximum surface tempera- specific gas or vapor to be encountered. tures specified in 503.5. (3) Interior of a Control Panel.In the interior of a control FPN: Luminaires and other heat-producing apparatus, panel containing instrumentation utilizing or measuring switches, circuit breakers, and plugs and receptacles are flammable liquids, gases, or vapors, electrical equipment potential sources of ignition and are investigated for suit- suitable for Class I, Division 2 locations shall be permitted. ability in classified locations. Such types of equipment, as well as cable terminations for entry into explosionproof Combustible gas detection equipment shall be fisted for Class enclosures, are available as listed for Class I, Division 2 I, Divisions 1, for the appropriate material group, and for the locations. Fixed wiring, however, may utilize wiring meth- detection of the specific gas or vapor to be encountered. ods that are not evaluated with respect to classified loca- tions. Wiring products such as cable, raceways,boxes,and (L) Other Protection Techniques. Other protection tech- fittings, therefore, are not marked as being suitable for niques used in equipment identified for use in hazardous Class 1, Division 2 locations.Also see 500.8(C)(6)(a). (classified) locations. (2) Equipment that has been identified for a Division 1 500.8 Equipment.Articles 500 through 504 require equip- location shall be permitted in a Division 2 location of the ment construction and installation that ensure safe perfor- same class, group, and temperature class and shall comply mance under conditions of proper use and maintenance. with (a) or (b) as applicable. FPN No. 1: It is important that inspection authorities and (a) Intrinsically safe apparatus having a control draw- users exercise more than ordinary care with regard to in- ing requiring the installation of associated apparatus for a stallation and maintenance. Division 1 installation shall be permitted to be installed in a FPN No. 2: Since there is no consistent relationship be- Division 2 location if the same associated apparatus is used tween explosion properties and ignition temperature, the for the Division 2 installation. two are independent requirements. (b) Equipment that is required to be explosionproof FPN No. 3: Low ambient conditions require special con- shall incorporate seals per 501.15(A) or (D) when the wir- sideration. Explosionproof or dust-ignitionproof equipment ing methods of 501.10(B) are employed. may not be suitable for use at temperatures lower than (3) Where specifically permitted in Articles 501 through —25°C (-13°F) unless they are identified for low- temperature service, However, at low ambient tempera- 503, general-purpose equipment or equipment in general- tures, flammable concentrations of vapors may not exist in purpose enclosures shall be permitted to be installed in a location classified as Class 1, Division I at normal ambi- Division 2 locations if the equipment does not constitute a ent temperature. source of ignition under normal operating conditions. (A) Suitability.Suitability of identified equipment shall be (4) Equipment that depends on a single compression seal, determined by one of the following: diaphragm, or tube to prevent flammable or combustible (1) Equipment listing or labeling fluids from entering the equipment shall he identified for a (2) Evidence of equipment evaluation from a qualified test- Class I,Division 2 location even if installed in an unclassified ing laboratory or inspection agency concerned with location. Equipment installed in a Class I, Division 1 location product evaluation shall be identified for the Class 1, Division I location. (3) Evidence acceptable to the authority having jurisdiction FPN: Equipment used for flow measurement is an example such as a manufacturer's Self-evaluation or an owner's of equipment having a single compression seal,diaphragm, engineering judgment. or tube. 70-360 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 500—HAZARDOUS (CLASSIFIED)LOCATIONS,CLASSES I, It.AND III, DIVISIONS 1 AND 2 500.8 (5)Unless otherwise specified,normal operating conditions Table 500.8(C) Classification of Maximum Surface for motors shall be assumed to be rated full-load steady Temperature conditions. Maximum Temperature (6) Where flammable gases, flammable liquid-produced Temperature Class vapors, combustible liquid-produced vapors, or combus- °C OF (T Code) tible dusts are or may be present at the same time, the 450 842 TI simultaneous presence of both shall be considered when 300 572 T2 determining the safe operating temperature of the electrical 280 536 T2A equipment. 260 500 T213 230 446 T2C FPN: The characteristics of various atmospheric mixtures 215 419 T2D of gases, vapors, and dusts depend on the specific material 200 392 T3 involved. 180 356 T3A 165 329 T313 (C) Marking. Equipment shall be marked to show the en- 160 320 T3C vironment for which it has been evaluated. Unless other- 135 275 T4 wise specified or allowed in (C)(6), the marking shall in- 120 248 T4A 100 212 T5 clude the information specified in (C)(1) through (C)(5). 85 185 T6 (1) Class. The marking shall specify the class(es) for (5) Ambient Temperature Range. For equipment rated which the equipment is suitable. for a temperature range other than -25°C to +40°C, the (2) Division. The marking shall specify the division if the marking shall specify the special range of ambient tempera- equipment is suitable for Division 2 only. Equipment suitable tures in degrees Celsius. The marking shall include either for Division 1 shall be permitted to omit the division marking. the symbol "Ta" or "Tamb." FPN: As an example, such a marking might be "-30°C :5 FPN: Equipment not marked to indicate a division, or T'a�+40°C." marked"Division I"or"Div. I,"is suitable for both Division I and 2 locations;see 500.8(B)(2). Equipment marked"Divi- (6) Special Allowances, sion 2"or"Div. 2" is suitable for Division 2 locations only, (a) General-Purpose Equipment. Fixed general-purpose (3) Material Classification Group. The marking shall equipment in Class I locations, other than fixed luminaires, specify the applicable material classification group(s) in ac- that is acceptable for use in Class 1, Division 2 locations shall cordance with 500.6. not be required to be marked with the class, division, group, temperature class, or ambient temperature range. Exceptive: Fixed luminaires marked for use only in Class (b) Dusttight Equipment. Fixed dusttight equipment, 1, Divisive 2 or Class 11, Divisive 2 locations shall not be other than fixed luminaires, that is acceptable for use in required to indicate the group. Class II, Division 2 and Class III locations shall not be (4) Equipment Temperature. The marking shall specify required to be marked with the class, division, group, tem- the temperature class or operating temperature at a 40°C perature class, or ambient temperature range. ambient temperature, or at the higher ambient temperature (c) Associated Apparatus. Associated intrinsically safe if the equipment is rated and marked for an ambient tem- apparatus and associated nonincendive field wiring appara- perature of greater than 40°C. The temperature class, if tus that are not protected by an alternative type of protec- provided, shall be indicated using the temperature class (T tion shall not be marked with the class, division, group, or Codes)shown in Table 500.8(C). Equipment for Class I and temperature class. Associated intrinsically safe apparatus Class II shall be marked with the maximum safe operating and associated nonincendive field wiring apparatus shall be temperature,as determined by simultaneous exposure to the marked with the class, division, and group of the apparatus combinations of Class I and Class II conditions. to which it is to be connected. (d) Simple Apparatus. "Simple apparatus"as defined in Exception; Equipment of the non-heat-producing type, Article 504, shall not be required to be marked with Class, such as junction boxes, conduit, and fittings, and equipment division, group, temperature class, or ambient temperature of the heat-producing type having a maximum temperature not more than 100°C shall not be required to have a range. marked operating temperature or temperature class. (D) Temperature. FPN: More than one marked temperature class or operat- (1) Class I Temperature. The temperature marking speci- ing temperature, for gases and vapors, dusts, and different fied in 500.8(C)shall not exceed the ignition temperature of ambient temperatures, may appear. the specific gas or vapor to be encountered. 2008 Edition NATIONAL ELECTRICAL CODE 70-361 500.9 ARTICLE 501—CLASS t LOCATIONS FPN: For information regarding ignition temperatures of FPN: Thread form specifications for NPT threads are lo- gases and vapors, see NFPA 497-2004, Recommended cated in ANSI/ASME B1.20.1-1983, Pipe Threads, Gen- Practice for the Cla.s.sificcuioa of Flantinable Liquids, eral Purpose(finch). Gases, or Vapors, and of Hazardous(Classified)Locations for Electrical Ins•tallatiom in Chemical Process Arens. (2) Equipment Provided with Threaded Entries for (2) Class Il Temperature. The temperature marking Metric Threaded Conduit or Fittings. For equipment specified in 500.8(C) shall be less than the ignition tem- with metric threaded entries,such entries shall be identified pera[ure of the specific dust to be encountered. For organic as being metric, or listed adapters to permit connection to dusts that may dehydrate or carbonize, the temperature conduit or NPT-threaded fittings shall be provided with the marking shall not exceed the lower of either the ignition equipment. Adapters shall be used for connection to con- temperature or 165'C ed ). duit or NPT-threaded fittings. Listed cable fittings that have metric threads shall be permitted to be used. FPN: See NFPA 499-2004, Recommended Practice for the Classification of Combustible Dusts and of Hazardous FPN: Threading specifications for metric threaded entries (Classified)Locations fbr Electrical Irtstallatiom in Chemi- are located in ISO 965/1-1980,Metric Screw Threads, and cal Process Areas, for minimum ignition temperatures of ISO 965/3-1980,Metric Screw Threads% specific dusts. (F) Fiber Optic Cable Assembly. Where a fiber optic The ignition temperature For which equipment was ap- cable assembly contains conductors that are capable of car- proved prior to this requirement shall be assumed to be as tying current, the fiber optic cable assembly shall be in- shown in Table 500.8(D)(2). stalled in accordance with the requirements of Articles 500, Table 500.8(D)(2) Class II Temperatures 501, 502, or 503, as applicable. Equipment(Such as Motors 500.9 Specific Occupancies. Articles 510 through 517 or Power Transformers) cover garages, aircraft hangars, motor fuel dispensing fa- Equipment That May Be Overloaded cilities, bulk storage plants, spray application, dipping and Not Subject coating processes, and health care facilities. to Normal Abnormal Overloading Operation Operation Class II Group °C OF °C OF °C OF E 200 392 200 392 200 392 ARTICLE 501 F 200 392 150 302 200 392 G 165 329 120 248 165 329 Class I Locations (E) Threading. All NPT threaded conduit and fittings re- I. General ferred to herein shall be threaded with a National (Ameri- can)Standard Pipe Taper(NPT)thread that provides a taper 501.1 Scope. Article 501 covers the requirements for elec- of 1 in 16 0/4-in. taper per foot). Conduit and fittings shall trical and electronic equipment and wiring for all voltages be made wrenchtight to prevent sparking when fault current in Class I, Division 1 and 2 locations where fire or explo- flows through the conduit system, and to ensure the explo- sion hazards may exist due to flammable gases or vapors or sionproof integrity of the conduit system where applicable. flammable liquids. Equipment provided with threaded entries for field wiring FPN: For the requirements for electrical and electronic connections shall be installed in accordance with equipment and wiring for all voltages in Class I, Zone 0, 500.8(E)(1)or(E)(2). Threaded entries into explosionproof Zone 1, or Zone 2 hazardous (classified) locations where equipment shall be made up with at least five threads fully fire or explosion hazards may exist due to flammable gases engaged. or vapors or flammable liquids, refer to Article 505. Exception: For listed explo.sionproof equipment, factory threaded NPT entries shall he tirade up with at least 41/a 501.5 Zone Equipment. Equipment listed and marked in thretrds f[rlly engaged. or with 505.9(C)(2) for use in Class I, Zone Q, 1, or 2 locations shall be permitted in Class I, Division 2 (1) Equipment Provided with Threaded Entries for locations for the same gas and with a suitable temperature NPT Threaded Conduit or Fittings. For equipment pro- class. Equipment listed and marked in accordance with vided with threaded entries for NPT threaded conduit or 505.9(C)(2) for use in Class 1, Zone 0 locations shall be fittings, listed conduit, conduit fittings, or cable fittings permitted in Class I, Division 1 or Division 2 locations for shall be used, the same gas and with a suitable temperature class. 70-362 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 501—CLASS I LOCATIONS 501.10 II. Wiring (2) Flexible Connections. Where necessary to employ flexible connections, as at motor terminals, flexible fittings 501.10 Wiring Methods. Wiring methods shalt comply listed for Class I, Division 1 locations or flexible cord in ac- with 501.10(A) or(B). cordance with the provisions of 501.140 shall be permitted. (A) Class I, Division 1. (3) Boxes and Fittings. All boxes and fittings shall be approved for Class I, Division 1. (1) General. In Class 1, Division I locations, the wiring methods in (a) through (d) shalt be permitted. (B) Class I, Division 2. (a) Threaded rigid metal conduit or threaded steel in- (1) General. In Class I, Division 2 locations,the following termediate metal conduit. wiring methods shall be permitted: (1) All wiring methods permitted in 501.10(A). Exception: Type PVC conduit and Type RTRC conduit (2) Threaded rigid metal conduit, threaded steel intermedi- shall be permitted where encased in a concrete envelope a ate metal conduit. minimum of 50 mm (2 in.) thick and provided with not less (3) Enclosed gasketed busways, enclosed gasketed wire- than 600 mm(24 in.) of cover measured from the top of the ways. conduit to grade. The concrete encasement shall be permit ted to he omitted where subject to the provisions of 514.8, (4) Type PLTC cable in accordance with the provisions of Article 725, or in cable tray systems. PLTC shall be Exception No. 2, and 515.8(A). Threaded rigid metal con- installed in a manner to avoid tensile stress at the ter- duit or threaded steel intermediate metal conduit shall be mination fittings. used for the last 600 min(24 in.) of the underground run to (5) Type ITC cable as permitted in 727.4. emergence or to the point of connection to the aboveground raceway. An equipment grounding conductor shall be in- (6) Type MI, MC, MV, or TC cable with termination fit- eluded to provide for electrical continuity of the raceway fit- tings, or in cable tray systems and installed in a manner .systen2 and for grounding of non—current-carrying metal to avoid tensile stress at the termination fittings. parts. (7) In industrial establishments with restricted public ac- cess where the conditions of maintenance and supervi- (b) Type MI cable with termination fittings listed for sion ensure, that only qualified persons service the in- the location. Type MI cable shall be installed and sup- stallation and where metallic conduit does not provide ported in a manner to avoid tensile stress at the termina- sufficient corrosion resistance,reinforced thermosetting tion fittings. resin conduit (RTRC), factory elbows, and associated (c) In industrial establishments with restricted public fittings, all Toarked with the suffix -YW, and Schedule 80 PVC conduit,factory elbows, and associated fittings access, where the conditions of maintenance and supervi- shall be permitted. sion ensure that only qualified persons service the installa- Where seals are required for boundary conditions as tion, Type MC-HL cable, listed for use in Class I, Zone 1, defined in 501.15(A)(4), the Division I wiring method or Division t locations, with a gas/vaportight continuous shall extend into the Division 2 area to time seal, which corrugated metallic sheath, an overall jacket of suitable shall be located on the Division 2 side of the Division polymeric material, a separate equipment grounding con- I—Division 2 boundary. ductor(s) in accordance with 250.122, and provided with (2) Flexible Connections. Where provision must be made termination fittings listed for the application. for limited flexibility, one or more of the following shall FPN: See 330.12 for restrictions on use of Type MC cable. also be permitted: (1) Flexible metal fittings. (d) In industrial establishments with restricted public (2) Flexible metal conduit with listed fittings. access, where the conditions of maintenance and supervi- (3) Liquidtight flexible metal conduit with listed fittings. sion ensure that only qualified persons service the installa- (4) Lttings.ght flexible nonmetallic conduit with listed tion, Type ITC-HL cable, listed for use in Class I, Zone 1, fittings. or Division 1 locations, with a gas/vaportight continuous corrugated metallic sheath, an overall jacket of suitable (5) Flexible cord listed for extra-hard usage and provided with listed bushed fittings. A conductor for use as an polymeric material and provided with termination fittings equipment grounding conductor shall be included in listed for the application. the flexible cord. FPN: See 727.4 and 727.5 for restrictions on use o€Type rX FPN: See 501.30(B) for grounding requirements where cable. flexible conduit is used. 2009 Edition NATIONAL EUCCRICAL CODE 70-363 501.15 ARTICLE 501—CLASS 1 LOCATIONS (3) Nonincendive Field Wiring. Nonincendive field wir- (1) The enclosure contains apparatus, such as switches,cir- ing shall be permitted using any of the wiring methods cuit breakers, fuses, relays, or resistors, that may pro- permitted for unclassified locations. Nonincendive field duce arcs, sparks, or high temperatures that are consid- wiring systems shall be installed in accordance with the ered to be an ignition source in normal operation. control drawing(s). Simple apparatus, not shown on the (2) The entry is metric designator 53 (trade size 2) or control drawing, shall be permitted in a nonincendive field larger and the enclosure contains terminals, splices, or wiring circuit, provided the simple apparatus does not in- taps. terconnect the nonincendive field wiring circuit to any other circuit. For the purposes of this section, high temperatures shall be considered to be any temperatures exceeding 80 percent FPN: Simple apparatus is defined in 504.2. of the autoignition temperature in degrees Celsius of the Separate nonincendive field wiring circuits shall be in- gas or vapor involved. stalled in accordance with one of the following: Exception to 501.15(A)(1)(1): Seals shall not be required (1) In separate cables for conduit entering an enclosure where such switches, cir- (2) In multiconductor cables where the,cot ductors of each cult breakers,fuses, relays, or resistors comply with one of circuit are within a grounded metal shield the following: (3) In multiconductor cables, where the conductors of each (1) Are enclosed within a chamber hermetically sealed circuit have insulation with a minimum thickness of against the entrance of gases or vapors 0.25 mm (0.01 in.) (2) Are inunersed in oil in accordance with 501,115(8)(1)(2) (4) Boxes and Fittings. Boxes and fittings shall not be (3) Are enclosed within a factorv-sealed explosionproof required to be explosionproof except as required by chamber located within the enclosure, identified for the 501.105(B)(1), 501.115(B)(1), and 501.150(B)(1). location, and marked "factory sealed" or equivalent, 501.15 Sealing and Drainage. Seals in conduit and cable unless the enclosure entry is metric designator 5.3(trade size 2) or!urger systems shall comply with 501.15(A) through (F). Sealing compound shall be used in Type Ml cable termination fit- (4) Are in nonincendive circuits tings to exclude moisture and other fluids from the cable Factory-sealed enclosures shall not be considered to insulation. serve as a seal for another adjacent explosionproof enclo- FPN No. 1: Seals are provided in conduit and cable sys- sure that is required to have a conduit seal. tems to minimize the passage of gases and vapors and pre- Conduit seals shall be installed within 450 mm (18 in.) vent the passage of flames from one portion of the electrical from the enclosure. Only explosionproof unions, couplings, installation to another through the conduit.Such communi- reducers, elbows, capped elbows, and conduit bodies simi- cation through Type MI cable is inherently prevented by lar to L,T, and Cross types that are not larger than the trade construction of the cable. Unless specifically designed and tested for the purpose, conduit and cable seals are not in- size of the conduit shall be permitted between the sealing tended to prevent the passage of liquids,gases,or vapors at fitting and the explosionproof enclosure. a continuous pressure differential across the seal. Even at differences in pressure across the seal equivalent to a few (2) Pressurized Enclosures. In each conduit entry into a inches of water, there may he a slow passage of gas or pressurized enclosure where the conduit is not pressurized vapor through a seal and through conductors passing as part of the protection system. Conduit seals shall be through the seal. See 501.15(E)(2). Temperature extremes installed within 450 mm (18 in.) from the pressurized en- and highly corrosive liquids and vapors can affect the abil- closure. ity of seals to perform their intended function. See 501.15(C)(2). FPN No. I: Installing the seal as close as possible to the FPN No. 2: Gas or vapor leakage and propagation of enclosure will reduce problems with purging the dead air- flames may occur through the interstices between the space in the pressurized conduit. strands of standard stranded conductors larger than 2 AWG. FPN No. 2: For further information, see NFPA 496-2003, Special conductor constructions, for example, compacted Standard for Purged and Pressurized Enclosures for Elec•- strands or sealing of the individual strands, are means of trical Equipment. reducing leakage and preventing the propagation or flames. (A) Conduit Seals, Class I, Division 1. In Class 1, Divi- (3) Two or More Explosionproof Enclosures.Where two or more explosionproof enclosures for which conduit seals lion 1 locations, conduit seals shall be located in actor- are required under 501.15(A)(I) are connected by nipples dance with SOLlS(A){1} through (A)(4}. or by runs of conduit not more than 900 mm (36 in.) long, (1) Entering Enclosures. In each conduit entry into an a single conduit seal in each such nipple connection or run explosionproof enclosure where either of the following of conduit shall be considered sufficient if located not more apply: than 450 mm (18 in.) from either enclosure. 70-364 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 501—CLASS I LOCATIONS 501.15 (4) Class I, Division 1 Boundary. In each conduit run Exception No. 1: Metal conduit that contains no unions, leaving a Class I, Division 1 location. The sealing fitting couplings, boxes, or fittings, and passes completely through shall be permitted on either side of the boundary of such a Class 1, Division 2 location with no fittings less than location within 3.05 m 00 ft) of the boundary and shall be 300 mm (12 in.) beyond each boundary, shall not be re- designed and installed so as to minimize the amount of gas quired to be sealed if the termination points of the unbroken or vapor within the Division 1 portion of the conduit from conduit are in unclassified locations. being communicated to the conduit beyond the seal. Except Exception No. 2: Conduit systems terminating at an un- for listed explosionproof reducers at the conduit seal, there classified location where a wiring method transition is shall be no union, coupling, box, or fitting between the made to cable tray, cablebus, ventilated busway, Type MI conduit seal and the point at which the conduit leaves the cable, or cable not installed in any cable tray or raceway Division 1 location. system shall not be required to be sealed where passing Exception No. 1: Metal conduit that contains no unions, from the Class 1, Division 2 location into the unclassified couplings, boxes, or fittings, and passes completely through location. The unclassified location shall be outdoors or if a Class I, Division I location with no fittings less than the conduit system is all in one room, it shall be permitted 300 mm (12 in.) beyond each boundary, shall nor require a to be indoors. The conduits shall not terminate at art enclo- conduit seal if the termination points of the unbroken con- sure containing an ignition source in normal operation. duit are in unclassified locations. Exception No. 3: Conduit systems passing from an enclo- Exception No. 2: For underground conduit installed in ac- sure or room that is unclassified as a result of pressuriza- cordance with 300.5 where the boundary is below grade, tion into a Class 1, Division 2 location shall not require a the sealing fitting shall be permitted to be installed after the seal at the boundary. conduit emerges from below grade, but there shall be no union, coupling, box, or fitting, other than listed explosion- FPN: For further information, refer to NFPA 496-2003, standard for Purged and Pressurized Enclosures for Elec- proof reducers at the sealing fitting, in the conduit between trical Equipment. the sealing fitting and tire point at which tire conduit Exception No. 4:Segments of aboveground conduit systems emerges from below grade. shall not be required to be sealed where passing from a (B) Conduit Seals, Class I, Division 2. In Class I, Divi- Class 1, Division 2 location into an unclassified location if sion 2 locations, conduit seals shall be located in actor- all of the following conditions are met: dance with 501.15(B)(1) and (13)(2). (1) No part of the conduit system segment passes through a (1) Entering Enclosures. For connections to enclosures Class 1, Division I location where the conduit contains that are required to be explosionproof, a conduit seal shall unions, couplings, boxes, or fittings within 300 mm be provided in accordance with 501.15(A)(1)(1) and (12 in.) of the Class 1, Division 1 location. (A)(3). All portions of the conduit run or nipple between (2) The conduit system segment is located entirely in out- the seal and such enclosure shall comply with 501.10(A). door locations. (2) Class 1, Division 2 Boundary. In each conduit run (3) The conduit system segment is not directly connected to passing from a Class 1, Division 2 location into an unclas- canned pumps, process or service connections for flow, sified location. The sealing fitting shall be permitted on Pressure, or analysis measurement, and so forth, that either side of the boundary of such location within 3.05 m depend on a single compression seal, diaphragm, or (10 ft) of the boundary. Rigid metal conduit or threaded tube to prevent flammable or combustible fluids from steel intermediate metal conduit shall be used between the entering the conduit system. sealing fitting and the point at which the conduit leaves the (4) The conduit system segment contains only threaded Division 2 location, and a threaded connection shall be metal conduit, unions, couplings, conduit bodies, and used at the sealing fitting. Except for listed reducers at the finings in the unclassified location. conduit seal, there shall be no union, coupling, box, or (5) The conduit system segment is sealed at its entry to fitting between the conduit seal and the point at which the each enclosure or fitting housing terminals, splices, or conduit leaves the Division 2 location. Conduits shall be taps in Class 1, Division 2 locations. sealed to minimize the amount of gas or vapor within the Division 2 portion of the conduit from being communicated (C) Class 1, Divisions 1 and 2. Seals installed in Class I, Division I and Division 2 locations shall comply with to the conduit beyond the seal. Such seals shall not be 501.15(C)(1) through (C)(6). required to be explosionproof but shall be identified for the purpose of minimizing passage of gases under normal op- Exception: Seals not required to be explosionproof by erating conditions and shall be accessible. 501.15(B)(2) or 504.70. 2008 Edition NATIONAL ELECTRICAL CODE 70-365 501.15 ARTICLE 501—CLASS I LOCATIONS (1) Fittings.Enclosures for connections or equipment shall (2) Cables Capable of Transmitting Gases or Vapors. be provided with an integral means for sealing, or sealing Cables in conduit with a gas/vaportight continuous sheath fittings listed for the location shall be used. Sealing fittings capable of transmitting gases or vapors through the cable shall be listed for use with one or more specific compounds core shall be sealed in the Division I location after remov- and shall be accessible. ing the jacket and any other coverings so that the sealing (2) Compound.The compound shall provide a seal against compound will surround each individual insulated conduc- assa a of as or vapors through the sea] fitting, shall not for and the outer jacket. p•.,� g g • P g f;, be affected by the surrounding atmosphere or liquids, and Exception: Multiconductor cables with a gas/vaportight shall not have a melting point of less than 93°C (200°F). continuous sheath capable of transmitting gases or vapors through the cable core shall be permitted to be considered (3) Thickness of Compounds.Except for listed cable seal- as a single conductor by sealing the cable in the conduit ing fittings, the thickness of the sealing compound in a com- within 450 mm (IS in.) of the enclosure and the cable end pleted seal shall not be less than the metric designator(trade within the enclosure by an approved means to minimize the size) of the sealing fitting expressed in the units of measure- entrance of gases or vapors and prevent the propagation of ment employed, and in no case less than 16 mm (5/s in.). flame into the cable core, or by other approved methods. (4) Splices and Taps.Splices and taps shall not be made in For shielded cables and twisted pair cables, it shall not be fittings intended only for sealing with compound, nor shall required to remove the shielding material or separate the other fittings in which splices or taps are made be filled twisted pair with compound. (3) Cables Incapable of Transmitting Gases or Vapors. (5) Assemblies. In an assembly where equipment that may Each multiconductor cable in conduit shall be considered as produce arcs, sparks, or high temperatures is located in a a single conductor if the cable is incapable of transmitting compartment separate from the compartment containing gases or vapors through the cable core. These cables shall splices or taps, and an integral seal is provided where con- be sealed in accordance with 501.15(A). ductors pass from one compartment to the other, the entire (E) Cable Seals,Class I,Division 2.In Class I,Division 2 assembly shall be identified for the location. Seals in con- locations, cable seals shall be located in accordance with duit connections to the compartment containing splices or 501.15(E)(1) through (E)(4). taps shall be provided in Class 1, Division I locations where required by 501.15(A)(I)(2). (1) Terminations. Cables entering enclosures that are re- (6) Conductor Fill. The cross-sectional area of the con- quired to be explosionproof shall be sealed at the point of ductors permitted in a seal shall not exceed 25 percent of entrance. The sealing fitting shall comply with 501.15(B)(1). Multiconductor cables with a gas/vaportight the crass-sectional area of a rigid metal conduit of the same continuous sheath capable of transmitting gases or vapors trade size unless it is specifically identified for a higher through the cable core shall be sealed in a listed fitting in percentage of fill, the Division 2 location after removing the jacket and any (D) Cable Seals,Class 1,Division 1.In Class 1, Division I other coverings so that the sealing compound surrounds locations, cable seals shall be located according to each individual insulated conductor in such a manner as to 501.15(D)(1) through (D)(3). minimize the passage of gases and vapors. Multiconductor cables in conduit shall be seated as described in 501.15(D). (1) At Terminations. Cable shall be sealed at all termina- tions.The sealing fitting shall comply with 501.15(C).Mul- Exception No. 1: Cables passing from an enclosure or ticonductor Type MC-HL cables with a gas/vaportight con- room that is unclassified as a result of Type Z pressurizu- tinuous corrugated metallic sheath and an overall jacket of tion into a Class I, Division 2 location shall not require a suitable polymeric material shall be sealed with a listed seal at the boundary. fitting after removing the jacket and any other covering so Exception No. 2: Shielded cables and twisted pair cables that the sealing compound surrounds each individual insu- shall not require the removal of the shielding material or sepa- lated conductor in such a manner as to minimize the pas- ration of the twisted pairs, provided the tenninution is by an sage of gases and vapors. approved means to minimize the entrance of gases or vapors and prevent propagation of flanne into the cable care. Exception: Shielded cables and heisted pair cables shall not require the removal of the shielding material or sepa- (2) Cables That Do Not Transmit Gases or Vapors. ration of the twisted pairs, provided the termination is by Cables that have a gas/vaportight continuous sheath and do an approved means to minimize the entrance of gases or not transmit gases or vapors through the cable core in excess vapors and prevent propagation of flame into the cable of the quantity permitted for seal fittings shall not be required core. to be sealed except as required in 501.15(E)(t).The minimum 70-366 NATIONAL EUCI'RICAL CODE 2008 Edition ARTICLE 501—CLASS I LOCATIONS 501.30 length of such cable run shall not be less than that length that temperature and pressure conditions to which they will be limits gas or vapor flow through the cable core to the rate subjected upon failure of the primary seal, unless other permitted for seal fittings [200 cm3/hr(0.007 ft3/hr)of air at a approved means are provided to accomplish this purpose. pressure of 1500 pascals (6 in. of water)l. Drains, vents, or other devices shall be provided so that FPN: The cable core does not include the interstices of the primary seal leakage will be obvious. conductor strands. FPN: See also the fine print notes to 501.15. (3) Cables Capable of Transmitting Gases or Vapors. Process-connected equipment that is listed and marked Cables with a gas/vaportight continuous sheath capable of "Dual Seal" shall not require additional process sealing transmitting gases or vapors through the cable core shall when used within the manufacturer's ratings. not be required to be sealed except as required in 501.15(E)(1), unless the cable is attached to process equip- 501.20 Conductor Insulation, Class I,Divisions 1 and 2. ment or devices that may cause a pressure in excess of 1500 Where condensed vapors or liquids may collect on,or come pascals (6 in. of water) to be exerted at a cable end, in which in contact with, the insulation on conductors, such insula- case a seal,barrier,or other means shall be provided to prevent tion shall be of a type identified for use under such condi- migration of flammables into an unclassified location. tions; or the insulation shall be protected by a sheath of Exception: Cables with an unbroken gas/vaportight con- lead or by other approved means. tinuous sheath shall be permitted to pass through a Class 1, Division 2 location without seals. 501.25 Uninsulated Exposed Parts, Class I, Divisions 1 and 2.There shall be no uninsulated exposed parts, such as (4) Cables Without Gas/Vaportight Sheath. Cables that electrical conductors, buses, terminals, or components, that do not have gas/vaportight continuous sheath shall be operate at more than 30 volts (15 volts in wet locations). sealed at the boundary of the Division 2 and unclassified These parts shall additionally be protected by a protection location in such a manner as to minimize the passage of technique according to 500.7(E), (F), or(G) that is suitable gases or vapors into an unclassified location. for the location. (F) Drainage. 501.30 Grounding and Bonding, Class I, Divisions l (1) Control Equipment. Where there is a probability that and 2. Wiring and equipment in Class 1, Division I and 2 liquid or other condensed vapor may be trapped within locations shall be grounded as specified in Article 250 and enclosures for control equipment or at any point in the in accordance with the requirements of 501.30(A) and (B). raceway system, approved means shall be provided to pre- (A) Bonding. The locknut-bushing and double-Iocknut vent accumulation or to permit periodic draining of such types of contacts shall not be depended on for bonding liquid or condensed vapor. purposes, but bonding jumpers with proper fittings or other (2) Motors and Generators. Where the authority having approved means of bonding shall be used. Such means of jurisdiction judges that there is a probability that liquid or bonding shall apply to all intervening raceways, fittings, condensed vapor may accumulate within motors or genera- boxes, enclosures, and so forth between Class I locations tors,joints and conduit systems shall be arranged to mini- and the point of grounding for service equipment or point mize the entrance of liquid. If means to prevent accumula- of grounding of a separately derived system. tion or to permit periodic draining are judged necessary, Exception: The specific bonding means shall be required such means shall be provided at the time of manufacture only to the nearest point where the grounded circuit con- and shall be considered an integral part of the machine. ductor and the grounding electrode are connected together (3) Canned Pumps, Process, or Service Connections, on the line side of the building or structure disconnecting etc. For canned pumps, process, or service connections for means as specified in 250.32(B), provided the branch- flow, pressure, or analysis measurement, and so forth, that circuit overcurrent protection is located on the load side of depend on a single compression seal, diaphragm, or tube to the disconnecting means. prevent flammable or combustible fluids from entering the FPN: See 250.100 for additional bonding requirements in electrical raceway or cable system capable of transmitting hazardous (classified) locations, fluids, an additional approved seal, barrier, or other means shall be provided to prevent the flammable or combustible (B) Types of Equipment Grounding Conductors. Flex- fluid from entering the raceway or cable system capable of ible metal conduit and liquidtight flexible metal conduit transmitting fluids beyond the additional devices or means, shall not be used as the sole ground-fault current path. if the primary seal fails. The additional approved seal or Where equipment bonding jumpers am installed, they shall barrier and the interconnecting enclosure shall meet the comply with 250.102. 2008 Edition NATIONAL ELECTRICAL CODE 70-367 501.35 ARTICLE 501—CLASS I LOCATIONS Exception: ht Class 1, Division 2 locations, the bonding (2) Not Containing Liquid That Will Burn, Transform- jumper shall be permitted to be deleted where all of the ers and capacitors that do not contain a liquid that will burn following conditions are met: shall be installed in vaults complying with 501.100(A)(1) (1) Listed liquidtight flexible metal conduit 1.8 m (6 ft) or or be identified for Class I locations. less in length, with fittings listed for grounding, is users. (B) Class I, Division 2. In Class 1, Division 2 locations, (2) Overc•urrent protection in the circuit is limited to 10 transformers and capacitors shall comply with 450.21 amperes or less, through 450.27. (3) The load is not a power utilization load. 501.105 Meters, Instruments, and Relays. 501.35 Surge Protection. (A) Class I, Division 1. In Class 1, Division I locations, (A) Class 1, Division 1. Surge arresters, surge-protective meters, instruments, and relays, including kilowatt-hour devices, and capacitors shall be installed in enclosures meters, instrument transformers, resistors, rectifiers, and identified for Class 1, Division 1 Iocations. Surge-protective thermionic tubes, shall be provided with enclosures identi- capacitors shall be of a type designed for specific duty. fied for Class 1, Division 1 locations. Enclosures for Class 1, Division 1 locations include explosionproof enclosures (B) Class I, Division 2. Surge arresters and surge- and purged and pressurized enclosures. protective devices shall be nonarcing, such as metal-oxide varistor(MOV)sealed type, and surge-protective capacitors FPN: See close 49h-2003,Sical E cl for Prer�c=d and Ares stari;ed Enclosures for Electrical Equipment. shall be of a type designed for specific duty. Enclosures shall be permitted to be of the general-purpose type. Surge (B) Class I, Division 2. In Class I, Division 2 locations, protection of types other than described in this paragraph meters, instruments, and relays shall comply with shall be installed in enclosures identified for Class I, Divi- 501.105(B)(1) through (13)(6). sion 1 locations. (1) Contacts. Switches, circuit breakers, and make-and- 501.40 Multiwire Branch Circuits. In a Class 1, Division I break contacts of pushbuttons, relays, alarm bells, and location, a multiwire branch circuit shall not be permitted, horns shall have enclosures identified for Class I, Division 1 locations in accordance with 501.105(A). Exception: Where the disconnect device(s)for the circuit opens all ungrounded conductors of the mnrltiwire circuit Exception: General-purpose enclosures .shall be perntit- simultaneousls, ted if current-interrupting contacts comply with one of the following: III. Equipment (1) Are immersed in oil (2) Are enclosed within a chamber that is hermetically 501.100 Transformers and Capacitors. sealed against the entrance n g f gases or vapors (A) Class 1, Division 1. In Class I, Division 1 locations, (3) Are in nonincendive circuits transformers and capacitors shall comply with 501.100(A)(1) (4) Are listed for Division 2 and (A)(2). (2) Resistors and Similar Equipment. Resistors, resis- (1) Containing Liquid That Will Burn.Transformers and tance devices, thermionic tubes, rectifiers, and similar capacitors containing a liquid that will burn shall be in- equipment that are used in or in connection with meters, stalled only in vaults that comply with 450.41 through instruments, and relays shall comply with 501.105(A). 450.48 and with (1) through (4) as follows: Exception: General-purpose-type enclosures shall be per- (1) There shall be no door or other communicating opening mitted if such equipment is without make-and-break or slid- between the vault and the Division 1 location. ing contacts(other than as provided in 501.105(B)(1)J and (2) Ample ventilation shall be provided for the continuous if the fnaxintum operating temperature of anyy exposed sur- removal of flammable gases or vapors. face will not exceed 80 percent of the ignition temperature (3) Vent openings or ducts shall lead to a safe location in degrees Celsius of the gas or vapor involved or has been outside of buildings. tested and found incapable of igniting the gas or vapor. (4) Vent ducts and openings shall be of sufficient area to This exception shall not apph• to thermionic tubes. relieve explosion pressures within the vault, and all (3) Without Make-or-Break Contacts. Transformer portions of vent ducts within the buildings shall be of windings, impedance coils, solenoids, and other windings reinforced concrete construction, that do not incorporate sliding or make-or-break contacts 70-365 NATIONAL ELECTRICAL CODE 2(W Edition ARTICLE 501—CLASS I LOCATIONS 502.120 shall be provided with enclosures. General-purpose-type performance of the function for which they are installed enclosures shall be permitted, shall be provided with enclosures identified for Class I, (4) General-Purpose Assemblies. Where an assembly is Division 1 locations in accordance with 501.105(A),unless made up of components for which general-purpose enclo- general-purpose enclosures are provided and any of the fol- sures are acceptable as provided in 501.105(B)(1), (13)(2), lowing apply: and (13)(3), a single general-purpose enclosure shall be ac- (1) The interruption of current occurs within a chamber ceptable for the assembly. Where such an assembly in- hermetically sealed against the entrance of gases and cludes any of the equipment described in 501.105(B)(2), vapors. the maximum obtainable surface temperature of any com- (2) The current make-and-break contacts are oil-immersed ponent of the assembly shall be clearly and permanently and of the general-purpose type having a 50-mm(2-in.) indicated on the outside of the enclosure. Alternatively, minimum immersion for power contacts and a 25-mm equipment shall be permitted to be marked to indicate the (1-in.) minimum immersion for control contacts. temperature class for which it is suitable, using the tem- perature class {T Code) of Table 500.8(C). (3) The interruption of current occurs within afactory- sealed explosionproof chamber. (5) Fuses.Where general-purpose enclosures are permitted (4) The device is a solid state, switching control without in 501.105(B)(1) through (8)(4), fuses for overcurrent pro- contacts, where the surface temperature does not ex- tection of instrument circuits not subject to overloading in ceed 80 percent of the ignition temperature in degrees normal use shall be permitted to be mounted in general- purpose enclosures if each such fuse is preceded by a Celsius of the gas or vapor involved. switch complying with 501.105(B)(1). (2) Isolating Switches. Fused or unfused disconnect and (6) Connections. To facilitate replacements, process con- isolating switches for transformers or capacitor banks that trol instruments shall be permitted to be connected through are not intended to interrupt current in the normal perfor- flexible cord, attachment plug, and receptacle, provided all mance of the function for which they are installed shall be of the following conditions apply: permitted to be installed in general-purpose enclosures. (1) A switch complying with 501.105(B)(1) is provided so (3) Fuses. For the protection of motors, appliances, and that the attachment plug is not depended on to interrupt lamps, other than as provided in 501.115(B)(4), standard current. plug or cartridge fuses shall be permitted,provided they are (2) The current does not exceed 3 amperes at 120 volts, placed within enclosures identified for the location;or fuses nominal. shall be permitted if they are within general-purpose enclo- (3) The power-supply cord does not exceed 900 mm (3 ft), sures, and if they are of a type in which the operating is of a type listed for extra-hard usage or for hard usage element is immersed in oil or other approved liquid, or the if protected by location, and is supplied through an operating element is enclosed within a chamber hermeti- attachment plug and receptacle of the locking and cally sealed against the entrance of gases and vapors, or the grounding type. fuse is a nonindicating, filled, current-limiting type. (4) Only necessary receptacles are provided. (5) The receptacle carries a label warning against unplug- (4) Fuses Internal to Luminaires. Listed cartridge fuses shall be permitted as supplementary protection within ging under load. luminaires. 501.115 Switches, Circuit Breakers, Motor Controllers, and Fuses. 501.120 Control Transformers and Resistors. Trans- formers, impedance coils, and resistors used as, or in con- (A) Class 1, Division 1. In Class I, Division i locations, junction with, control equipment for motors, generators, switches, circuit breakers, motor controllers, and fuses, in- and appliances shall comply with 501.120(A) and (B). cluding pushbuttons, relays, and similar devices, shall be provided with enclosures, and the enclosure in each case, (A) Class I, Division 1. In Class 1, Division 1 locations, together with the enclosed apparatus,shall be identified as a transformers, impedance coils, and resistors, together with complete assembly for use in Class I locations. any switching mechanism associated with them, shall be (B) Class I, Division 2. Switches, circuit breakers, motor provided with enclosures identified for Class I, Division l controllers, and fuses in Class I, Division 2 locations shall locations in accordance with 501.105(A). comply with 501.115(B)(1) through (13)(4). (B) Class 1, Division 2. In Class I, Division 2 locations, (1) Type Required. Circuit breakers, motor controllers, control transformers and resistors shall comply with and switches intended to interrupt current in the normal 501.120(B)(1) through (13)(3). 2008 Edition NATIONAL ELECTRICAL CODE 70-369 S01.125 ARTICLE 501 —CLASS 1 LOCATIONS (1) Switching Mechanisms. Switching mechanisms used (B) Class I, Division 2. In Class I, Division 2 locations, in conjunction with transformers, impedance coils, and re- motors, generators, and other rotating electrical machinery sistors shall comply with 501.115{B}, in which are employed sliding contacts, centrifugal or other (2) Coils and Windings.Enclosures for windings of trans- types of switching mechanism (including motor overcur- rent, overloading, and overtemperature devices), or integral formers,solenoids, or impedance coils shall be permitted to resistance devices, either while starting or while running, be of the general-purpose type. shall be identified for Class I, Division 1 locations, unless (3) Resistors. Resistors shall be provided with enclosures; such sliding contacts, switching mechanisms, and resis- and the assembly shall be identified for Class I locations, tance devices are provided with enclosures identified for unless resistance is nonvariable and maximum operating tem- Class I, Division 2 locations in accordance with perature, in degrees Celsius, will not exceed 80 percent of the 501.105(B). The exposed surface of space beaters used to ignition temperature of the gas or vapor involved or has been prevent condensation of moisture during shutdown periods tested and found incapable of igniting the gas or vapor. shall not exceed 80 percent of the ignition temperature in degrees Celsius of the gas or vapor involved when operated 501.125 Motors and Generators. at rated voltage, and the maximum surface temperature [based on a 40°C (104°F) ambientl shall be permanently (A) Class I, Division 1. In Class I, Division 1 locations, marked on a visible nameplate mounted on the motor. Oth- motors, generators, and other rotating electrical machinery erwise, space heaters shall be identified for Class 1, Divi- shall be one of the following: Sion 2 locations. In Class I, Division 2 locations, the instal- ([) identified for Class I, Division 1 locations lation of open or nonexplosionproof enclosed motors, such (2) Of the totally enclosed type supplied with positive- as squirrel-cage induction motors without brushes, switch- pressure ventilation from a source of clean air with ing mechanisms, or similar arc-producing devices that are discharge to a safe area, so arranged to prevent ener- not identified for use in a Class I, Division 2 location, shall gizing of the machine until ventilation has been estab- be permitted. lished and the enclosure has been purged with at least FPN No. l: It is important to consider the temperature of 10 volumes of air, and also arranged to automatically internal and external surfaces that may be exposed to the de-energize the equipment when the air supply fails flammable atmosphere. (3) Of the totally enclosed inert gas-filled type supplied FPN No. 2: It is important to consider the risk of ignition due to currents arcing across discontinuities and overheat- with a suitable reliable source of inert gas for pressur- ing of parts in multisection enclosures of large motors and izing the enclosure, with devices provided to ensure a generators. Such motors and generators may need equipo- positive pressure in the enclosure and arranged to au- tential bonding jumpers across joints in the enclosure and tomatically de-energize the equipment when the gas from enclosure to ground. Where the presence of ignitible supply fails gases or vapors is suspected, clean-air purging may be needed immediately prior to and during start-up periods. (4) Of a type designed to be submerged in a liquid that is FPN No. 3: For further information on the application of flammable only when vaporized and mixed with air, or electric motors in Class 1, Division 2 hazardous (classified) in a gas or vapor at a pressure greater than atmospheric locations, see IEEE Std. 1349-2001, IEEE Guide for the and that is flammable only when mixed with air; and Application of Electric Motors in Class 1, Division 2 Ham the machine is so arranged to prevent energizing it until ardous (Classified) Locations. it has been purged with the liquid or gas to exclude air, and also arranged to automatically de-energize the 501.130 Luminaires. Luminaires shall comply with 501.130(A) or (B). equipment when the supply of liquid or gas or vapor fails or the pressure is reduced to atmospheric (A) Class I, Division 1. In Class I, Division i locations, Totally enclosed motors of the types specified in luminaires shall comply with 501.130(A)(1) through 501.125(A)(2)or(A)(3) shall have no external surface with (A)(4). an operating temperature in degrees Celsius in excess of (1) Luminaires. Each luminaire shall he identified as a 80 percent of the ignition temperature of the gas or vapor complete assembly for the Class I, Division I location and involved. Appropriate devices shall be provided to detect shall be clearly marked to indicate the maximum wattage of and automatically de-energize the motor or provide an ad- lamps for which it is identified. Luminaires intended for equate alarm if there is any increase in temperature of the portable use shall be specifically listed as a complete as- motor beyond designed limits.Auxiliary equipment shall be sembly for that use. of a type identified for the location in which it is installed. (2) Physical Damage. Each luminaire shall be y g protected FPN: See D 2155-69,ASTM Test Procedure, against physical damage by a suitable guard or by location. 70-370 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 501—CLASS I LOCATIONS 501.140 (3) Pendant Luminaires.Pendant luminaires shall be sus- (6) Starting Equipment. Starting and control equipment pended by and supplied through threaded rigid metal con- for electric-discharge lamps shall comply with 501.120(B). duit stems or threaded steel intermediate conduit stems,and Exception: A thermal protector potted into a thermally threaded joints shall be provided with set-screws or other protected fluorescent lamp ballast if the luminaire is iden- effective means to prevent loosening. For stems longer than tified for the location. 300 mm (12 in.), permanent and effective bracing against lateral displacement shall be provided at a level not more 501.135 Utilization Equipment. than 300 mm (12 in.) above the lower end of the stem, or flexibility in the form of a fitting or flexible connector iden- (A) Class I,Division 1. In Class I, Division 1 locations,all tified for the Class 1, Division 1 location shall be provided utilization equipment shall be identified for Class I, Divi- not more than 300 mm (12 in.)from the point of attachment sion 1 locations. to the supporting box or fitting. (B) Class I,Division 2. In Class I, Division 2 locations, all (4) Supports. Boxes, box assemblies, or fittings used for utilization equipment shall comply with 501.135(8)(1) the support of luminaires shall be identified for Class I through (13)(3). locations. (1) Heaters. Electrically heated utilization equipment shall (B) Class 1, Division 2. In Class 1, Division 2 locations, conform with either item (1) or item (2): luminaires shall comply with 501.130(B)(1)through(B)(6). (1) The heater shall not exceed 80 percent of the ignition temperature in degrees Celsius of the gas or vapor in- (1) Luminaires. Where lamps are of a size or type that volved on any surface that is exposed to the gas or may, under normal operating conditions, reach surface tem- vapor when continuously energized at the maximum peratures exceeding 80 percent of the ignition temperature rated ambient temperature. If a temperature controller in degrees Celsius of the gas or vapor involved, luminaires is not provided, these conditions shall apply when the shall comply with 501.130(A)(1) or shall be of a type that heater is operated at 120 percent of rated voltage. has been tested in order to determine the marked operating temperature or temperature class {T Code). Exception No. 1: For motor-mounted anticondensation space heaters, see 501.125. (2) Physical Damage. Luminaires shall be protected from Exception No. 2: Where a current-limiting device is ap- physicaI damage by suitable guards or by location. Where plied to the circuit serving the heater to limit the current in there is danger that falling sparks or hot metal from lamps the heater to a value less than that required to raise the or luminaires might ignite localized concentrations of flam- heater surface temperature to 80 percent of the ignition mable vapors or gases, suitable enclosures or other effec- temperature. tive protective means shall be provided. (2) The heater shall be identified for Class I, Division 1 (3) Pendant Luminaires. Pendant luminaires shall be sus- locations. pended by threaded rigid metal conduit stems, threaded Exception to (2): Electrical resistance heat tracing identi- steel intermediate metal conduit stems, or other approved fled far Class I, Division 2 locations. means. For rigid stems longer than 300 mm (12 in.), per- manent and effective bracing against lateral displacement h Motors. Motors of motor-driven utilization equipment s shall be provided at a level not more than 300 nun (12 in.) shall comply with 501.125(B). above the lower end of the stem, or flexibility in the form (3) Switches, Circuit Breakers,and Fuses. Switches, cir- of an identified fitting or flexible connector shall be pro- cuit breakers, and fuses shall comply with 501.115(B). vided not more than 300 mm (12 in.) from the point of attachment to the supporting box or fitting. 501.140 Flexible Cords, Class 1, Divisions I and 2. (4) Portable Lighting Equipment. Portable lighting (A) Permitted Uses. Flexible cord shall be permitted: equipment shall comply with 501.130(A)(1). (1) For connection between portable lighting equipment or Exception: Where portable lighting equipment is mounted other portable utilization equipment and the fixed por- on movable stands and is connected by flexible cords, as tion of their supply circuit. covered in 501.140, it shall be permitted, where mounted in (2) For that portion of the circuit where the fixed wiring any position, if it conforms to 501.130(B)(2). methods of 501.10(A) cannot provide the necessary de- gree of movement for fixed and mobile electrical u6liza- (5) Switches. Switches that are a part of an assembled tion equipment,and the flexible cord is protected by loca- fixture or of an individual lampholder shall comply with tion or by a suitable guard from damage and only in an 501.115(B)(1). industrial establishment where conditions of maintenance 2008 Edition NATIONAL ELECTR1CAI,CODE 70-371 501.145 ARTICLE 502—CLASS II LOCATIONS and engineering supervision ensure that only qualified horns shall have enclosures identified for Class I, Division persons install and service the installation. 1 locations in accordance with 501.105(A), (3) For electric submersible pumps with means for re- Exception: General-purpose enclosures shall be permitted moval without entering the wet-pit. The extension of if current-interrupting contacts are one of the following: the flexible cord within a suitable raceway between the wet-pit and the power source shall be permitted. (1) Immersed in oil (4) For electric mixers intended for travel into and out of (2) Enclosed within a chamber hermeticall-v sealed against open-type mixing tanks or vats. the entrance of gases or vapors (3) ht nonincendive circuits (B) Installation. Where flexible cords are used, the cords (4) Fart of a listed nonincendive component shall comply with all of the following: (1) Be of a type listed for extra-hard usage (2) Resistors and Similar Equipment. Resistors, resis- (2) Contain, in addition to the conductors of the circuit, an tance devices, thermionic tubes, rectifiers, and similar equipment grounding conductor complying with equipment shall comply with 501.105(B)(2). 400.23 (3) Protectors. Enclosures shall be provided for Iightning (3) Be connected to terminals or to supply conductors in an protective devices and for fuses. Such enclosures shall be approved manner permitted to be of the general-purpose type. (4) Be supported by clamps or by other suitable means in such a manner that there is no tension on the terminal {4) Wiring and Sealing. All wiring shall comply with 501.10(B), 501.15(B), and 501.15(C). connections (5) Be provided with suitable seals where the flexible cord enters boxes, fittings, or enclosures of the explosion- proof type Exception to (5): Seals shall not be required as provided in ARTICLE 502 501.10(B) and 501.105(B)(6). Class II Locations (6) Be of continuous length. 1. General FPN: See 501.20 for flexible cords exposed to liquids hav- ing a deleterious effect on the conductor insulation. 502.1 Scope. Article 502 covers the requirements for elec- trical and electronic equipment and wiring for ali voltages 501.145 Receptacles and Attachment Plugs, Class I, Di- in Class II, Division 1 and 2 locations where fire or explo- visions 1 and 2. Receptacles and attachment plugs shall be sion hazards may exist due to combustible dust. of the type providing for connection to the equipment • grounding conductor of a flexible cord and shall be identi- 502.5 Explosionproof Equipment. Explosionproof equip- fied for the location. ment and wiring shall not be required and shall not be acceptable in Class It locations unless identified for such Exception: As provided in 501.105(B)(6). locations. 501.150 Signaling, Alarm, Remote-Control, and Com- munications Systems. II. Wiring (A) Class 1,Division 1. In Class I,Division 1 locations, all 502.10 Wiring Methods. Wiring methods shall comply apparatus and equipment of signaling, alarm, remote- with 502.10(A) or (B). control, and communications systems, regardless of volt- age,shall be identified for Class I,Division I locations,and (A) Class II, Division 1. all wiring shall comply with 501.10(A), 501.15(A), and (1) General. In Class II, Division 1 locations, the wiring 501.15(C). methods in (1) through (4) shall be permitted: (B) Class I, Division 2. In Class 1, Division 2 locations, (1) Threaded rigid metal conduit, or threaded steel inter- signaling, alarm, remote-control, and communications sys- mediate metal conduit. tems shall comply with 501.150(B)(1) through (B)(4). (2) Type MI cable with termination fittings listed for the location. Type MI cable shall be installed and sup- (1) Contacts. Switches, circuit breakers, and make-and- ported in a manner to avoid tensile stress at the termi- break contacts of pushbuttons, relays, alarm bells, and nation fittings. 70-372 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 502—CLASS II LOCATIONS 502,25 (3) In industrial establishments with limited public access, (2) Flexible Connections. Where provision must be made where the conditions of maintenance and supervision for flexibility, 502.10(A)(2) shall apply. ensure that only qualified persons service the installa- tion, Type MC-HL cable, listed for use in Class 1I, (3) Nonincendive Field Wiring. Nonincendive field wir- Division 1 locations, with a gaslvaportight continuous ing shall be permitted using any of the wiring methods corrugated metallic sheath, an overall jacket of suitable permitted for unclassified locations. Nonincendive field polymeric material, a separate equipment grounding wiring systems shall be installed in accordance with the conductor(s) in accordance with 250.122, and provided control drawing(s). Simple apparatus, not shown on the with termination fittings listed for the application, shall control drawing, shall be permitted in a nonincendive field be permitted. wiring circuit, provided the simple apparatus does not in- (4) Fittings and boxes shall be provided with threaded terconnect the nonincendive field wiring circuit to any other bosses for connection to conduit or cable terminations circuit. and shall be dusttight. Fittings and boxes in which taps, FPN: Simple apparatus is defined in 504.2. joints, or terminal connections are made, or that are used in Group E locations, shall be identified for Class Separate nonincendive field wiring circuits shall be in- II locations. stalled in accordance with one of the following: (1) In separate cables (2) Flexible Connections. Where necessary to employ (2) In multiconductor cables where the conductors of each flexible connections, one or more of the following shall circuit are within a grounded metal shield also be permitted: (3) In multiconductor cables where the conductors of each (1) Dusttight flexible connectors circuit have insulation with a minimum thickness of (2) Liquidtight flexible metal conduit with listed fittings 0.25 mm (0.01 in.) (3) Liquidtight flexible nonmetallic conduit with listed fittings (4) Boxes and Fittings. All boxes and fittings shall be (4) Interlocked armor Type MC cable having an overall dusttight, jacket of suitable polymeric material and provided with termination fittings listed for Class II, Division 502.15 Sealing, Class II,Divisions 1 and 2. Where a race- 1 locations. way provides communication between an enclosure that is (5) Flexible cord listed for extra-hard usage and provided required to be dust-ignitionproof and one that is not, suit- with bushed fittings. Where flexible cords are used, able means shall be provided to prevent the entrance of dust they shall comply with 502.140. into the dust-ignitionproof enclosure through the raceway. One of the following means shall be permitted: FPN: See 502.30(B) for grounding requirements where (1) A permanent and effective seal flexible conduit is used. (2) A horizontal raceway not less than 3.05 m (10 ft) long (B) Class 1I, Division 2. (3) A vertical raceway not less than 1.5 m (5 ft) long and extending downward from the dust-ignitionproof en- (1) General. In Class 11, Division 2 locations, the follow- closure ing wiring methods shall be permitted: (4) A raceway installed in a manner equivalent to(2)or(3) (1) All wiring methods permitted in 502.10(A). that extends only horizontally and downward from the (2) Rigid metal conduit, intermediate metal conduit, elec- dust-ignition proof enclosures trical metallic tubing, dusttight wireways. (3) Type MC or MI cable with listed termination fittings. Where a raceway provides communication between an en- closure that is required to be dust-ignitionproof and an enclo- (4) Type PLTC in cable trays. sure in an unclassified location,seals shall not be required. (5) Type ITC in cable trays. Sealing fittings shall be accessible, (6) Type MC, MI, or TC cable installed in ladder, venti- Seals shall not be required to be explosionproof. lated trough, or ventilated channel cable trays in a FPN: Electrical sealing putty is a method of sealing. single layer, with a space not less than the larger cable diameter between the two adjacent cables, shall be the wiring method employed. 502.25 Uninsulated Exposed Parts, Class H,Divisions 1 and 2.There shall be no uninsulated exposed parts,such as Exception to (6): Type MC cable listed for use in Class 11, electrical conductors, buses, terminals, or components, that Division 1 locations shall be permitted to be installed with- operate at more than 30 volts (15 volts in wet locations). out the spacings required by (6). These parts shall additionally be protected by a protection 2008 Edition NATIONAL ELECTRICAL CODE 70-373 502.30 ARTICLE 502—CLASS II LOCATIONS technique according to 500.7(E), (F), or(G) that is suitable III. Equipment for the location. 502,100 Transformers and Capacitors. 502.30 Grounding and Bonding, Class II, Divisions 1 (A) Class II, Division 1. In Class 11, Division I locations, and 2. Wiring and equipment in Class II, Division I and 2 transformers and capacitors shall comply with locations shall be grounded as specified in Article 250 and 502.100(A)(1) through (A)(3). in accordance with the requirements of 502.30(A) and (B). (1) Containing Liquid That Will Burn.Transformers and (A) Bonding, The locknut-bushing and double-locknut capacitors containing a liquid that will burn shall be in- types of contact shall not be depended on for bonding pur- stalled only in vaults complying with 450.41 through poses, but bonding jumpers with proper fittings or other 450.48, and, in addition, (1), (2), and (3) shall apply. approved means of bonding shall be used. Such means of (1) Doors or other openings communicating with the Divi- bonding shall apply to all intervening raceways, fittings, Sion I location shall have self-closing fire doors on boxes, enclosures, and so forth, between Class II locations both sides of the wall, and the doors shall be carefully and the point of grounding for service equipment or point fitted and provided with suitable seals (such as weather of grounding of a separately derived system. stripping) to minimize the entrance of dust into the vault. Exception: The s1mcifrc bonding means shall onh be re- quired to the nearest point where the grounded circuit can- (2) Vent openings and ducts shall communicate only with the outside air. duc•tor and the grounding electrode conductor are con- nected together on the line side of the building or structure (3) the outs pressure-relief openings communicating with disconnecting means cis specified in 250.32(B) if the the outside air shall be provided. branch-circuit overrurrent protection is located on the load (2) Not Containing Liquid That Will Burn. Transform- side of the disconnecting means. ers and capacitors that do not contain a liquid that will burn shall be installed in vaults complying with 450.41 through hazeSee 250.100 for addions. bonding requirements in 450.48 or be identified as a complete assembly, including hazardous {classilied) locations. terminal connections for Class lI locations, (B) Types of Equipment Grounding Conductors. Liq- (3) Metal Dusts. No transformer or capacitor shall be in- uidtight flexible metal conduit shall not be used as the sole stalled in a location where dust from magnesium, alumi- ground-fault current path.Where equipment bonding jump- num, aluminum bronze powders, or other metals of simi- ers are installed, they shall comply with 250.102. larly hazardous characteristics may be present. E.rception: In Class 11, Division 2 locations, the bonding juniper shall he permitted to be deleted inhere all of the (B) Class II, Division 2. In Class II, Division 2 locations, transformers and capacitors shall comply with following conditions are met: 502.100(B)(1) through (13)(3). (1) Listed liquidtight flevible metal conduit 1.8 to (6 ft) or less in length, with fittings listed for grorouliri��, is used. capacitors Containing Liquid That Will Burn.Transformers and (2) Overc•urreitt protection in the circuit is limited to 10 capacitors containing a liquid that will burn shall be in- stalled in vaults that comply with 450.41 through 450.48, amperes or less. (3) The load is not a power utilization load. (2) Containing Askarel. Transformers containing askarel and rated in excess of 25 kVA shall be as follows: 502.35 Surge Protection — Class II, Divisions 1 and 2. (1) Provided with pressure-relief vents Surge arresters and surge-protective devices installed in a (2) Provided with a means for absorbing any gases gener- Class I1, Division 1 location shall be in suitable enclosures. ated by arcing inside the case, or the pressure-relief Surge-protective capacitors shall be of a type designed for vents shall be connected to a chimney or blue that will specific duty. carry such gases outside the building (3) Have an airspace of not less than 150 mm (6 in.) be- 502.40 Muldwire Branch Circuits.In a Class 11, Division I tween the transformer cases and any adjacent combus- location, a multiwire branch circuit shall not he permitted, tible material Exception: Where the disconnect device(s)for the circuit (3) Dry-Type Transformers. Dry-type transformers shall opens all ungrounded conductors of the multiwire circuit be installed in vaults or shall have their windings and ter- simultaneously. urinal connections enclosed in tight metal housings without 70-374 NATIONAL 6LF.CI•RICAL COM 2tHi8 Edition ARTICLE 502—CLASS II LOCATIONS 502.128 ventilating or other openings and shall operate at not over Exception: Where the maximum normal operating tem- 600 volts, nominal. perature of the resistor will not exceed 120°C (248°F), nonadjustable resistors or resistors that are part of an au- 502.115 Switches, Circuit Breakers, Motor Controllers, tomatically timed starting sequence shall be permitted to and Fuses. have enclosures complying with 502.120(B)(2). (A) Class II, Division 1. In Class II, Division 1 locations, 502.125 Motors and Generators. switches,circuit breakers, motor controllers, and fuses shall comply with 502.115(A)(1) and (A)(2). (A) Class 11, Division 1. In Class 1I, Division 1 locations, motors, generators, and other rotating electrical machinery (1) Type Required. Switches, circuit breakers, motor con- shall be in conformance with either of the following: trollers, and fuses, including pushbuttons, relays, and simi- lar devices, shall be provided with identified dust- (I) Identified for Class Il, Division 1 locations ignitionproof enclosures. (2) Totally enclosed pipe-ventilated, meeting temperature limitations in 502.5 (2) Metal Dusts.In locations where dust from magnesium, aluminum, aluminum bronze powders, or other metals of (B) Class I1, Division 2. In Class 11, Division 2 locations, similarly hazardous characteristics may be present, fuses, motors, generators, and other rotating electrical equipment switches, motor controllers, and circuit breakers shall have shall be totally enclosed nonventilated, totally enclosed enclosures identified for such locations. pipe-ventilated, totally enclosed water-air-cooled, totally enclosed fan-cooled or dust-ignitionproof for which maxi- (B) Class II, Division 2. In Class 1I, Division 2 locations, mum full-load external temperature shall be in accordance enclosures for fuses, switches, circuit breakers, and motor with 500.8(D)(2) for normal operation when operating in controllers, including pushbuttons, relays, and similar de- free air (not dust blanketed) and shall have no external vices, shall be dusttight. openings. 502.120 Control 'Transformers and Resistors. Exception: If the authority having jurisdiction believes ac- cumulations of nonconductive, nonabrasive dust will be (A) Class II, Division 1. In Class II, Division 1 locations, moderate and if machines can be easily reached for routine control transformers, solenoids, impedance coils, resistors, cleaning and maintenance, the following shall be permitted and any overcurrent devices or switching mechanisms as- to be installed: sociated with them shall have dust-ignitionproof enclosures (1) Standard open-type machines without sliding contacts, identified for Class II locations. No control transformer, centrifugal or other types of switching mechanism (in- impedance coil, or resistor shall be installed in a location cluding motor overcurrent, overloading, and overtenr- where dust from magnesium, aluminum, aluminum bronze perature devices), or integral resistance devices powders, or other metals of similarly hazardous character- (2) Standard open-type machines with such contacts, istics may be present unless provided with an enclosure switching mechanisms, or resistance devices enclosed identified for the specific location. within dusttight housings without ventilating or other (B) Class 11, Division 2. In Class 11, Division 2 locations, openings transformers and resistors shall comply with 502.120(B)(1) (3) Self-cleaning textile motors of the squirrel-cage type through (13)(3). 502.128 Ventilating Piping. Ventilating pipes for motors, (1) Switching Mechanisms. Switching mechanisms (in- generators, or other rotating electrical machinery, or for cluding overcurrent devices) associated with control trans- enclosures for electrical equipment, shall be of metal not formers, solenoids, impedance coils, and resistors shall be less than 0.53 mm (0.021 in.) in thickness or of equally provided with dusttight enclosures. substantial noncombustible material and shall comply with (2) Coils and Windings. Where not located in the same all of the following: enclosure with switching mechanisms, control transform- (1) Lead directly to a source of clean air outside of build- ers, solenoids, and impedance coils shall be provided with ings tight metal housings without ventilating openings or shall (2) Be screened at the outer ends to prevent the entrance of be installed in dusttight enclosures. Effective January 1, small animals or birds 2011, only dusttight enclosures shall be permitted. (3) Be protected against physical damage and against rust- (3) Resistors. Resistors and resistance devices shall ing or other corrosive influences have dust-ignitionproof enclosures identified for Class II Ventilating pipes shall also comply with 502.128(A) locations. and (B). 2008 Edition NATIONAL ELECTRICAL CODE 70-375 502.130 ARTICLE 502—CLASS lI LOCATIONS (A) Class 11, Division 1. In Class Il, Division 1 locations, be provided where the cord enters the luminaire and the ventilating pipes, including their connections to motors or outlet box or fitting. Flexible cord shall not serve as the to the dust-ignitionproof enclosures for other equipment, supporting means for a fixture. shall be dusttight throughout [heir length. For metal pipes, (q) Supports. Boxes, box assemblies, or fittings used for seams and joints shall comply with one of the following: the support of luminaires shall be identified for Class II (1) Be riveted and soldered locations. (2) Be bolted and soldered (3) Be welded (B) Class II, Division 2. In Class II, Division 2 locations, luminaires shall comply with 502.13{1(6)(1)through(B)(5). (4} Be rendered dusttight by some other equally effective means (1) Portable Lighting Equipment. Portable lighting equipment shall be identified for Class II locations. They (B) Class II, Division 2. In Class II, Division 2 locations, shall be clearly marked to indicate the maximum wattage of ventilating pipes and their connections shall be sufficiently lamps for which they are designed. tight to prevent the entrance of appreciable quantities of (2) Fixed Lighting. Luminaires for fixed lighting, where dust into the ventilated equipment or enclosure and to pre- not of a type identified for Class II locations, shall be pro- vent the escape of sparks, flame, or burning material that vided with dusttight enclosures. Each fixture shall be might ignite dust accumulations or combustible material in clearly marked to indicate the maximum wattage of the the vicinity. For metal pipes, lock seams and riveted or lamp that shall be permitted without exceeding an exposed welded joints shall be permitted; and tight-fitting slip joints surface temperature in accordance with 500.8(D)(2) under shall be permitted where some flexibility is necessary, as at normal conditions of use. connections to motors. (3) Physical Damage. Luminaires for fixed lighting shall 502.130 Luminaires. Luminaires shall comply with be protected from physical damage by suitable guards or by 502.130(A) and (B). location. (A) Class II, Division 1. In Class II, Division I locations, (4) Pendant Luminaires.Pendant luminaires shall be sus- luminaires for fixed and portable lighting shall comply with pended by threaded rigid metal conduit stems, by threaded 502.130(A)(1) through (A)(4). steel intermediate metal conduit stems, by chains with ap- proved fittings, or by other approved means. For rigid (1) Fixtures. Each luminaire shall be identified for Class 1I stems longer than 300 mm (12 in.),permanent and effective locations and shall be clearly marked to indicate the maxi- bracing against lateral displacement shall be provided at a mum wattage of the lamp for which it is designed. In loca- level not more than 300 mm(12 in.) above the lower end of tions where dust from magnesium, aluminum, aluminum the stem, or flexibility in the form of an identified fitting or bronze powders, or other metals of similarly hazardous a flexible connector shall be provided not more than characteristics may be present, luminaires for fixed or por- 300 mm (12 in.) from the point of attachment to the sup- table lighting and all auxiliary equipment shall be identified porting box or fitting. Where wiring between an outlet box for the specific location. or fitting and a pendant luminaire is not enclosed in con- (2) Physical Damage. Each luminaire shall be protected duit, flexible cord listed for hard usage shall be used. Flex- against physical damage by a suitable guard or by location. ible cord shall not serve as the supporting means for a fixture. (3) Pendant Luminaires. Pendant luminaires shall be sus- (5) Electric-Discharge Lamps. Starting and control pended by threaded rigid metal conduit stems, by threaded equipment for electric-discharge lamps shall comply with steel intermediate metal conduit stems, by chains with ap- the requirements of 502.120(B). proved fittings, or by other approved means. For rigid stems longer than 300 mm (12 in.),permanent and effective 502.135 Utilization Equipment. bracing against lateral displacement shall be provided at a (A) Class II, Division 1. In Class 11, Division I locations, level not more than 300 mm (12 in.)above the lower end of all utilization equipment shall be identified for Class 11 the stem, or flexibility in the form of a fitting or a flexible locations. Where dust from magnesium, aluminum, alumi- connector listed for the location shall be provided not more num bronze powders, or other metals of similarly hazard- than 300 mm (12 in.) from the point of attachment to the ous characteristics may be present,such equipment shall be supporting box or fitting. Threaded joints shall be provided identified for the specific location. with set screws or other effective means to prevent loosen- ing. Where wiring between an outlet box or fitting and a (B) Class 11, Division 2. In Class I1, Division 2 locations, pendant luminaire is not enclosed in conduit, flexible cord all utilization equipment shall comply with 502.135(B)(1) listed for hard usage shall be used, and suitable seals shall through (13)(4). 70-376 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 502—CLASS II LOCATIONS 502.150 (1) Heaters.Electrically heated utilization equipment shall (A) Class 1I, Division 1. In Class II, Division 1 locations, be identified for Class II locations. signaling, alarm, remote-control, and communications sys- E.rceptinn: Metal-enclosed radiant heating panel equip- tems; and meters,instruments, and relays shall comply with 502.150(A)(1) through (A)(5). ment shall be dusttight and marked in accordance with 500.8(C). (1) Contacts.Switches, circuit breakers,relays,contactors, fuses and current-breaking contacts for bells, horns, howl- (2) Motors. Motors of motor-driven utilization equipment ers, sirens, and other devices in which sparks or arcs may shall comply with 502.125(B). be produced shall be provided with enclosures identified for (3) Switches, Circuit Breakers, and Fuses. Enclosures a Class II location. for switches, circuit breakers, and fuses shall be dusttight. Exception: Where current-breaking contacts are immersed (4) Transformers, Solenoids, Impedance Coils, and Re- in oil or where the interruption of current occurs within a sistors. Transformers, solenoids, impedance coils, and re- chamber sealed against the entrance of dust, enclosures sistors shall comply with 502.120(B). shall be permitted to be of the general-purpose type. (2) Resistors and Similar Equipment. Resistors, trans- 502.140 Flexible Cords — Class II, Divisions 1 and 2. formers, choke coils, rectifiers, thermionic tubes, and other Flexible cords used in Class II locations shall comply with heat-generating equipment shall be provided with enclo- all of the following: sures identified for Class 11 locations. (1) Be of a type listed for extra-hard usage Exception: Where resistors or similar equipment are im- Exception: Flexible cord listed for hard usage as permitted mersed in oil or enclosed in a chamber sealed against the by 502.130(A)(3) and (B)(d), entrance of dust, enclosures shall be permitted to be of the (2) Contain, in addition to the conductors of the circuit, an general-purpose type. equipment grounding conductor complying with 400.23 (3) Rotating Machinery.Motors,generators, and other ro- (3) Be connected to terminals or to supply conductors in an tating electrical machinery shall comply with 502.125(A). approved manner (4) Combustible, Electrically Conductive Dusts. Where (4) Be supported by clamps or by other suitable means in dusts are of a combustible, electrically conductive nature, such a manner that there will be no tension on the all wiring and equipment shall be identified for Class II terminal connections locations. (5) Be provided with suitable seals to prevent the entrance (5) Metal Dusts.Where dust from magnesium, aluminum, of dust where the flexible cord enters boxes or fittings aluminum bronze powders, or other metals of similarly that are required to be dust-ignitionproof hazardous characteristics may be present, all apparatus and 502.145 Receptacles and Attachment Plugs. equipment shall be identified for the specific conditions. (A) Class II, Division 1. In Class II, Division 1 locations, (B) Class 11, Division 2. In Class II, Division 2 locations, signaling, alarm, remote-control, and communications sys- receptacles and attachment plugs shall be of the type pro' and meters, instruments, and relays shall comply with viding for connection to the equipment grounding conduc- tams; and me) through (B)(4). for of the flexible cord and shall be identified for Class II locations. (1) Contacts. Contacts shall comply with 502.150(A)(1), or contacts shall have tight metal enclosures designed to (B) Class II, Division 2. In Class II, Division 2 locations, minimize the entrance of dust and shall have telescoping or receptacles and attachment plugs shall be of the type that fight-fitting covers and no openings through which, after provides for connection to the equipment grounding con- installation, sparks or burning material might escape or ductor of the flexible cord and shall be designed so that shall be installed in dusttight enclosures. Effective January connection to the supply circuit cannot be made or broken 1, 2011, only dusttight enclosures shall be permitted. while live parts are exposed. Exception: In nonincendive circuits, enclosures shall be 502.150 Signaling,Alarm, Remote-Control,and Commu- permitted to be of the general-purpose type. nications Systems; and Meters, Instruments,and Relays. (2) Transformers and Similar Equipment.The windings FPN: See Article 800 for rules governing the installation of and terminal connections of transformers, choke coils, and communications circuits. similar equipment shall comply with 502.120(B)(2). 2008 Edition NATIONAL ELECTRICAL CODE 70-377 503.1 ARTICLE 503—CLASS III LOCATIONS (3) Resistors and Similar Equipment. Resistors, resis- FPN: See 503.30(B) for grounding requirements where tance devices, thermionic tubes, rectifiers, and similar flexible conduit is used. equipment shall comply with 502.120(B)(3). (3) Nonincendive Field Wiring. Nonincendive field wir- • (4) Rotating Machinery.Motors,generators, and other ro- ing shall be permitted using any of the wiring methods tating electrical machinery shall comply with 502.125(B). permitted for unclassified locations.Nonincendive field wiring systems shall be installed in accordance with the control draw- . ing(s). Simple apparatus, not shown on the control drawing, shall be permitted in a nonincendive field wiring circuit, pro- vided the simple apparatus does not interconnect the nonin- ARTICLE 503 cendive field wiring circuit to any other circuit. Class III Locations FPN: Simple apparatus is defined in 504.2. Separate nonincendive field wiring circuits shall be in- I. General stalled in accordance with one of the following: 503,1 Scope. Article 503 covers the requirements for elec- (1) In separate cables trical and electronic equipment and wiring for all voltages (2) In multiconductor cables where the conductors of each in Class III, Division 1 and 2 locations where fire or explo- circuit are within a grounded metal shield sion hazards may exist due to ignitible fibers/flyings. (3) In multiconductor cables where the conductors of each circuit have insulation with a minimum thickness of 503.5 General. Equipment installed in Class III locations 0.25 mm (0.01 in.) shall be able to function at full rating without developing sur- face temperatures high enough to cause excessive dehydration (B) Class III, Division 2. In Class 111, Division 2 loca- or gradual carbonization of accumulated fibers/flyings. Or- tions, the wiring method shall comply with 503,10(A). ganic material that is carbonized or excessively dry is highly Exception: In sections, compartments, or areas used solely susceptible to spontaneous ignition. The maximum surface for storage and containing no machinery, open ►viring on temperatures under operating conditions shall not exceed insulators shall be pennilted where installed in accordance 165°C (329°F) for equipment that is not subject to overload- with Article 398, but only on condition that protection as ing, and 120°C (248°F} for equipment (such as motors or required by 398.15(C) he provided where conductors are power transformers) that may be overloaded. not root in roof spaces and are well out of reach of sources FPN: For electric trucks, see NFPA 505-2006, Fire Safety, of physical damage. Standard for Powered Industrial Trucks Including 7:ype Designations, Areas of Use, Conversions, Maintenance, 503.25 Uninsulated Exposed Parts, Class I11, Divisions and Operation. 1 and 2.There shall be no uninsulated exposed parts, such as electrical conductors, buses, terminals, or components, that operate at more than 30 volts (15 volts in wet loca- tions). These parts shall additionally be protected by a pro- 503.10 Wiring Methods. Wiring methods shall comply tection technique according to 500.7(E), (F), or (G) that is with 503.10(A) or (B). suitable for the location. (A) Class III, Division 1. In Class III, Division I loca- Exception: As provided in 503.155. tions, the wiring method shall be rigid metal conduit, rigid nonmetallic conduit, intermediate metal conduit, electrical 503.30 Grounding and Bonding — Class III, Divisions metallic tubing, dusttight wireways, or Type MC or MI 1 and 2. Wiring and equipment in Class III, Division I and cable with listed termination fittings. 2 locations shall be grounded as specified in Article 250 and with the fallowing additional requirements in (1) Boxes and Fittings. All boxes and fittings shall be 503.30(A) and (B). dusttight. (A) Bonding. The locknut-bushing and double-locknut (2) Flexible Connections. Where necessary to employ types of contacts shall not be depended on for bonding flexible connections, dusttight flexible connectors, liq- purposes, but bonding jumpers with proper fittings or other uidtight flexible metal conduit with listed fittings, liq- approved means of bonding shall be used. Such means of uidtight flexible nonmetallic conduit with listed fittings, or bonding shall apply to all intervening raceways, fittings, flexible cord in compliance with 503.140 shall be used. boxes, enclosures, and so forth, between Class III locations 70-378 NATIONAL EUCTRICAL CODE 2008 Edition ARTICLE 503—CLASS III LOCATIONS 503.130 and the point of grounding for service equipment or point a rotating electrical machine and where such machine is of grounding of a separately derived system. readily accessible for routine cleaning and maintenance, Exception: The specific bonding means shall only be re- one of the following shall be permitted: quired to the nearest point where the grounded circuit con- (1) Self-cleaning textile motors of the squirrel-cage type ductor and the grounding electrode conductor are con- (2) Standard open-type machines without sliding contacts, nected together on the line side of the building or structure centrifugal or other types of switching mechanisms, in- disconnecting means as specified in 250.32(B) if the cluding motor overload devices branch-circuit overcurrent protection is located on the load (3) Standard open-type machines having such contacts, side of the disconnecting means. switching mechanisms, or resistance devices enclosed FPN: See 250.100 for additional bonding requirements in within tight housings without ventilating or other hazardous (classified) locations. openings (B) Types of Equipment Grounding Conductors. Liq- 503.128 Ventilating Piping—Class III,Divisions 1 and uidtight flexible metal conduit shall not be used as the sole 2. Ventilating pipes for motors,generators,or other rotating ground-fault current path.Where equipment bonding jump- electrical machinery, or for enclosures for electric equip- ers are installed, they shall comply with 250.102. ment, shall be of metal not less than 0.53 mm(0.021 in.) in thickness, or of equally substantial noncombustible mate- Exception: In Class 111, Division 1 and 2 locations, the rial, and shall comply with the following: bonding juniper shall be permitted to be deleted where all of the following conditions are met: (1) Lead directly to a source of clean air outside of buildings (2) Be screened at the outer ends to prevent the entrance of (1) Listed liyuidtight flexible metal 1.8 m (6 ft) or less in small animals or birds length, with fittings listed for grounding, is used. (3) Be protected against physical damage and against rust- (2) Overcurrent protection in the circuit is limited to 10 ing or other corrosive influences amperes or less. (3) The load is not a power utilization load. Ventilating pipes shall be sufficiently tight, including their connections, to prevent the entrance of appreciable quantities of fiberslilyings into the ventilated equipment or III. Equipment enclosure and to prevent the escape of sparks,flame,or burn- 503.100 Transformers and Capacitors — Class III, Di- ing material that might ignite accumulations of fibers/flyings visions I and 2. Transformers and capacitors shall comply or combustible material in the vicinity. For metal pipes, lock with 502.100(B). seams and riveted or welded joints shall be permitted; and tight-fitting slip joints shall be permitted where some flexibil- 503.115 Switches, Circuit Breakers, Motor Controllers, ity is necessary, as at connections to motors. and Fuses— Class ill, Divisions 1 and 2. Switches, cir- cuit breakers, motor controllers, and fuses, including push- 503.130 Luminaires — Class III, Divisions 1 and 2. buttons, relays, and similar devices, shall be provided with (A) Fixed Lighting. Luminaires for fixed lighting shall dusttight enclosures, provide enclosures for lamps and lampholders that are de- signed to minimize entrance of fibers/#lyings and to prevent 503.120 Control Transformers and Resistors — Class the escape of sparks, burning material, or hot metal. Each III, Divisions 1 and 2. Transformers, impedance coils, and luminaire shall be clearly marked to show the maximum resistors used as, or in conjunction with, control equipment wattage of the lamps that shall be permitted without ex- for motors, generators, and appliances shall be provided ceeding an exposed surface temperature of 165°C (329°F) with dusttight enclosures complying with the temperature under normal conditions of use, limitations in 503.5. (B) Physical Damage. A luminaire that may be exposed to 503.125 Motors and Generators — Class Ill, Divisions physical damage shall be protected by a suitable guard. 1 and 2. In Class III, Divisions 1 and 2 locations, motors, generators, and other rotating machinery shall be totally (C) Pendant Luminaires. Pendant luminaires shall be suspended by stems of threaded rigid metal conduit, enclosed nonventilated, totally enclosed pipe ventilated, or totally enclosed fan cooled. threaded intermediate metal conduit, threaded metal tubing of equivalent thickness, or by chains with approved fittings. Exception: In locations where, in the judgment of the au- For stems longer than 300 mm (12 in.), permanent and thority having jurisdiction, only moderate accumulations of effective bracing against lateral displacement shall be pro- lint or flyings are likely to collect on, in, or in the vicinity of vided at a level not more than 300 mm 02 in.) above the 2008 Edition NATIONAL ELECCRICAL CODE 70-379 503.135 ARTICLE 504—INTRINSICALLY SAFE SYSTEMS lower end of the stem, or flexibility in the form Of an 503.150 Signaling, Alarm, Remote-Control, and Local identified fitting or a flexible connector shall be provided Loudspeaker Intercommunications Systems — Class not more than 300 mm(12 in.)from the point of attachment III, Divisions 1 and 2. Signaling, alarm, remote-control, to the supporting box or fitting. and local loudspeaker intercommunications systems shall comply with the requirements of Article 503 regarding wir- (D) Portable Lighting Equipment. Portable lighting ing methods, switches, transformers, resistors, motors, lu- equipment shall be equipped with handles and protected minaires, and related components. with substantial guards. Lampholders shall be of the un- switched type with no provision for receiving attachment 503.155 Electric Cranes, Hoists, and Similar Equip- plugs. There shall be no exposed current-carrying metal ment— Class III, Divisions 1 and 2. Where installed for parts, and all exposed non-current-carrying metal parts operation over combustible fibers or accumulations of fly- shall be grounded. In all other respects, portable lighting ings, traveling cranes and hoists for material handling,trav- equipment shall comply with 503.130(A). eling cleaners for textile machinery, and similar equipment shall comply with 503.155(A) through (D). 503.135 Utilization Equipment—Class III, Divisions 1 and 2. (A) Power Supply. The power supply to contact conduc- tors shall be electrically isolated from all other systems, (A) Heaters. Electrically heated utilization equipment ungrounded,and shall be equipped with an acceptable ground shall be identified for Class III locations. detector that gives an alarm and automatically de-energizes the contact conductors in case of a fault to ground or gives a (B) Motors. Motors of motor-driven utilization equipment visual and audible alarm as long as power is supplied to the shall comply with 503.125. contact conductors and the ground fault remains. (C) Switches, Circuit Breakers, Motor Controllers, and (B) Contact Conductors. Contact conductors shall be lo- Fuses. Switches, circuit breakers, motor controllers, and cated or guarded so as to be inaccessible to other than fuses shall comply with 503.115. authorized persons and shall be protected against accidental contact with foreign objects. 503.140 Flexible Cords — Class III, Divisions 1 and 2. (C) Current Collectors. Current collectors shall be ar- Flexible cords shall comply with the following: ranged or guarded so as to confine normal sparking and (1) Be of a type listed for extra-hard usage prevent escape of sparks or hot particles. To reduce spark- (2) Contain, in addition to the conductors of the circuit, an ing, two or more separate surfaces of contact shall be pro- equipment grounding conductor complying with 400.23 vided for each contact conductor. Reliable means shall be (3) Be connected to terminals or to supply conductors in an provided to keep contact conductors and current collectors approved manner free of accumulations of lint or flyings. (4) Be supported by clamps or other suitable means in such a manner that there will be no tension on the terminal wit Control Equipment. Control equipment shall comply with 503.115 and 503.120. connections (5) Be provided with suitable means to prevent the en- 503.160 Storage Battery Charging Equipment— Class trance of fiberstflyings where the cord enters boxes or III, Divisions 1 and 2. Storage battery charging equipment fittings shall be located in separate rooms built or lined with sub- stantial noncombustible materials. The rooms shall be con- 503.145 Receptacles and Attachment Plugs—Class III, strutted to prevent the entrance of ignitible amounts of Divisions 1 and 2. Receptacles and attachment plugs shall flyings or lint and shall be well ventilated. be of the grounding type, shall be designed so as to mini- mize the accumulation or the entry of fibers/flyings, and shall prevent the escape of sparks or molten particles. Exception: In locations where, in the judgment of the au- ARTICLE 504 thority having jurisdiction, only moderate accumulations of Intrinsically Safe Systems lint or flyings are likely to collect in the vicinity of a recep- tacle, and where such receptacle is readily accessible for routine cleaning, general-purpose grounding-type recep- 504.1 Scope. This article covers the installation of intrin- tacles mounted so as to minimize the entry of ftbers/flyings sically safe(I.S.) apparatus,wiring,and systems for Class 1, shall be permitted. II, and III locations. 70-380 NATIONAL ELECTRICAL CODE 2(x)8 Edition ARTICLE 504—INTRINSICALLY SAFE SYSTEMS 504.10 FPN: For further information, see ANSlASA=RP 12.06.01 and is compatible with the intrinsic safety of the circuit in 2003, Wiring Methods for Hazardous(Classified)Locations which it is used. Instrumentation —Part 1: Intrinsic Safety: FPN: The following apparatus are examples of simple ap- 504.2 Definitions. paratus: (a) Passive components, for example, switches,june- Associated Apparatus.Apparatus in which the circuits are tion boxes, resistance temperature devices, and simple not necessarily intrinsically safe themselves but that affect semiconductor devices such as LEDs the energy in the intrinsically safe circuits and are relied on (b) Sources of stored energy consisting of single com- to maintain intrinsic safety. Associated apparatus may be pottents in simple circuits with well-defined parameters,for example,capacitors or inductors,whose values arc consid- ered when determining the overall safety of the system (1) Electrical apparatus that has an alternative-type protec- (c) Sources of generated energy, for example,thermo- tion for use in the appropriate hazardous (classified) couples and photocells, which do not generate more than location 1.5 V, 100 mA, and 25 mW (2) Electrical apparatus not so protected that shall not be 504.3 Application of Other Articles. Except as modified used within a hazardous (classified) location by this article, all applicable articles of this Code shall apply. FPN No. 1: Associated apparatus has identified intrinsi- cally safe connections for intrinsically safe apparatus and 504.4 Equipment. All intrinsically safe apparatus and as- also may have connections for nonintrinsically safe sociated apparatus shall be listed. apparatus. FPN No. 2: An example of associated apparatus is an in- Exception: Simple apparatus, as described on the control trinsic safety barrier, which is a network designed to limit drawing, shall not be required to be listed. the energy (voltage and current) available to the protected circuit in the hazardous (classified) location, under speci- 504.10 Equipment Installation. fied fault conditions. Control Drawing. See the definition in 500.2. (A) Control Drawing. Intrinsically safe apparatus, associ- ated apparatus, and other equipment shall be installed in Different Intrinsically Safe Circuits. Intrinsically safe cir- accordance with the control drawing(s). cuits in which the possible interconnections have not been evaluated and identified as intrinsically safe, Exception: A simple apparatus that does not interconnect intrinsically safe circuits. Intrinsically Safe Apparatus. Apparatus in which all the circuits are intrinsically safe. FPN No. 1: The control drawing identification is marked on the apparatus. Intrinsically Safe Circuit, A circuit in which any spark or FPN No. 2: Associated apparatus with a marked Um of thermal effect is incapable of causing ignition of a mixture less than 250 V may require additional overvoltage protec- of flammable or combustible material in air under pre- tion at the inputs to limit any possible fault voltages to less scribed test conditions. than the Um marked on the prWuet. FPN: Test conditions are described in ANSIIUL 913-1997, (B) Location. Intrinsically safe apparatus shall be permit- Standard fir Safety, Intrinsically Safe Apparatus and Asso- ted to be installed in any hazardous (classified) location for ciated Apparatus for Use in Class 1, 11, and III, Division 1, which it has been identified. General-purpose enclosures Hazardous(Classified) Locations. shall be permitted for intrinsically safe apparatus. Intrinsically Safe System. An assembly of interconnected Associated apparatus shall be permitted to be installed intrinsically safe apparatus, associated apparatus, and inter- in any hazardous (classified) location for which it has been connecting cables, in that those parts of the system that identified or, if protected by other means, permitted by Ar- may be used in hazardous (classified) locations are intrin- ticles 501 through 503 and Article 505. sically safe circuits. Simple apparatus shall be permitted to be installed in any hazardous (classified) location in which the maximum one An intrinsically safe system may include more than surface temperature of the simple apparatus does not ex- ceed the ignition temperature of the flammable gases or Simple Apparatus. An electrical component or combina- vapors, flammable liquids, combustible dusts, or ignitible tion of components of simple construction with well- fibers/flyings present. defined electrical parameters that does not generate more For simple apparatus, the maximum surface tempera- than l.5 volts, 100 milliamps, and 25 milliwatts, or a pas- ture can be determined from the values of the output power sive component that does not dissipate more than 1.3 watts from the associated apparatus or apparatus to which it is 2009 Edition NATIONAL ELECTRICAL CODE 70-3$1 504.20 ARTICLE 504—INTRINSICALLY SAFE SYSTEMS connected to obtain the temperature class. The temperature secured, or by a grounded metal partition or an approved class can be determined by: insulating partition. (I) Reference to Table 504.10(B) FPN: No. 20 gauge sheet metal partitions 0.91 mm (2} Calculation using the formula: (0.0359 in.)or thicker are generally considered acceptable. T= P„Ri1, f T,a,nd, Exception No. 2: Where either (1) all of the intrinsically where: safe circuit conductors or(2)all of the nonintrinsicall}'safe T is the surface temperature circuit conductors are in grounded metal-sheathed or P„ is the output power marked on the associated appa- metal-clad cables where the sheathing or cladding is ca- ratus or intrinsically safe apparatus f carrvin,able o I g fault current to ground. R& is the thermal resistance of the simple apparatus T,,,,,I, is the ambient temperature (normally 40°C) and FPN: Cables meeting the requirements of Articles 330 and reference Table 500.8(0) 332 are typical of those considered acceptable. In addition, components with a surface area smaller Exception No. 3: Intrinsically safe circuits in a Division 2 than 10 cm`(excluding lead wires) may be classified as T5 or Zone 2 location shall be permitted to be installed in a if their surface temperature does not exceed 150°C. raceway, cable tray, or cable along with nonincendive field Table 504,10(B) Assessment for T4 Classification According wiring Circuits when installed in accordance with to Component Size and Temperature 504.30(B)' Exception No. 4: Intrinsically safe circuits passing through Requirement for T4 a Division 2 or Zone 2 location to supply apparatus that is Total Surface Area Classification (Based on 40°C located in a Division 1, Zone 0 or Zone I location shall be Excluding Lead Wires Ambient Temperature) permitted to be installed in a raceway, cable tray, or cable <20 mmz Surface temperature 15275°C along with nonincendive field wiring circuits when installed ?20 mm` <10 cm` Surface temperature 5200°C in accordance with 504.30($). ?20 mm` Power not exceeding 1.3 W* FPN: Nonincendive field wiring circuits are described in "Reduce to 1.2 W with an ambient of 60'C or 1.0 W with 80°C 501,10(B)(3),502.10(B)(3),503.10(B)(3),505.15(C)(1)(g), ambient temperature, and 506.15(C)(7). FPN: The following apparatus are examples of simple up- (2) Within Enclosures. Conductors of intrinsically safe paratus: circuits shall be separated from conductors of nonintrinsi- (1) Passive components, for example, switches, junction tally safe circuits by one of the following means: boxes, resistance temperature devices, and simple (1) Separation by at least 50 mm(2 in.) from conductors of semiconductor devices such as LEDs (2) Sources of generated energy, for example, thermo- any nonintrinsically safe circuits. couples and photocells, which do not generate more (2) Separation from conductors of nonintrinsically safe cir- than 1.5 V, 100 mA, and 25 mW cuits by use of a grounded metal partition 0.91 mm (0.0359 in.) or thicker. 504.20 Wiring Methods. Any of the wiring methods suit- able (3) Separation from conductors of nonintrinsically safe cir- for unclassified locations, including those covered by cuits by use of an approved insulating.partition. Chapter 7 and Chapter 8, shall be permitted for installing intrinsically safe apparatus. Sealing shall be as provided in (4) Where either(1)all of the intrinsically safe circuit con- 504.70, and separation shall be as provided in 504.30. ductors or (2) all of the nonintrinsically safe circuit conductors are in grounded metal-sheathed or metal- 504.30 Separation of Intrinsically Safe Conductors. clad cables where the sheathing or cladding is capable of carrying fault current to ground. (A) From Nonintrinsically Safe Circuit Conductors. FPN: Cables meeting the requirements of Articles 330 and (1) In Raceways, Cable Trays, and Cables. Conductors 332 are typical of these considered acceptable. of intrinsically safe circuits shall not be placed in any race- (5) All conductors shall be secured so that any conductor way, cable tray, or cable with conductors of any nonintrin- that might come loose from a terminal cannot come in sically safe circuit. contact with another terminal. Exception No. 1: Where conductors of intrinsically safe FPN No. 1: The use of separate wiring compartments for circuits are separated from conductors of nonintrinsically the intrinsically safe and nonintrinsically safe terminals is a safe circuits by a distance of at least 50 mm (2 in.) and typical method of complying with this requirement. 70-382 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 504—INTRINSICALLY SAFE SYSTEMS 544.80 FPN No. 2: Physical barriers such as grounded metal par- electrode shall be as specified in 250.52(A)(1), (A)(2), titions or approved insulating partitions or approved re- (A)(3), and (A)(4) and shall comply with 250.30(A)(7). stricted access wiring ducts separated from other such ducts Sections 250.52(A)(5), (A)(7), and (A)(8) shall not be used by at least 19 nim (;/a in.) can be used to help ensure the required separation of the wiring. if any of the electrodes specified in 250.52(A)(1), (A)(2), (3) Other (Not in Raceway or Cable IYay Systems). • (A)(3), or (A)(4) are present. Conductors and cables of intrinsically safe circuits run in 504.60 Bonding. other than raceway or cable tray systems shall be separated by at least 50 mm (2 in,) and secured from conductors and (A) Hazardous Locations. In hazardous (classified) loca- cables of any nonintrinsically safe circuits. Lions, intrinsically safe apparatus shall be bonded in the hazardous (classified) location in accordance with 250.100. Exception: Where either (I) all of the intrinsically safe circuit conductors are in Type MI or MC cables or(2)all of (B) Unclassified. In unclassified locations, where metal the nonintrinsically safe circuit conductors are in raceways raceways are used for intrinsically safe system wiring in or Type M1 or MC cables where the sheathing or cladding hazardous (classified) locations, associated apparatus shall is capable of carrying fault current to ground. be bonded in accordance with 501.30(A), 502.30(A), (B) From Different Intrinsically Safe Circuit Conduc- 503.30(A), 505.25, or 506.25 as applicable. tors. Different intrinsically safe circuits shall be in separate 504,70 Sealing.Conduits and cables that are required to be cables or shall be separated from each other by one of the seated by 501.15, 502.15, 505.16, and 506.16 shall be following means: sealed to minimize the passage of gases, vapors, or dusts. (1) The conductors of each circuit are within a grounded Such seals shall not be required to be explosionproof or metal shield. flameproof but shall be identified for the purpose of mini- (2) The conductors of each circuit have insulation with a mixing passage of gases, vapors, or dusts under normal minimum thickness of 0.25 mm (0.01 in.). operating conditions and shall'be accessible. Exception: Unless otherwise identified. Exception: Seals shall not be required for enclosures that (3) The clearance between two terminals for connection of contain only intrinsically safe apparatus, except as re- field wiring of different intrinsically safe circuits shall quired by 501.15(F)(3). be at least 6 mm (0.25 in.) unless this clearance is 504.80 Identification. Labels required by this section shall permitted to be reduced by the control drawing. be suitable for the environment where they are installed 504.50 Grounding. with consideration given to exposure to chemicals and sunlight. (A) Intrinsically Safe Apparatus,Enclosures, and Race- ways. Intrinsically safe apparatus, enclosures, and race- (A) Terminals.Intrinsically safe circuits shall be identified ways, if of metal, shall be connected to the equipment at terminal and junction locations in a manner that will grounding conductor. prevent unintentional interference with the circuits during FPN: In addition to an equipment grounding conductor testing and servicing. connection, a connection to a grounding electrode may be (B) Wiring.Raceways,cable trays, and other wiring meth- needed for some associated apparatus, for example, zener ods for intrinsically safe system wiring shall be identified diode barriers, if specified in the control drawing. See ANSI/ISA-RP 12.06.01-2003, Wiring Methods for Hazard- with permanently affixed labels with the wording "Intrinsic ous (Classified) Locations Instrumentation — Part 1: In- Safety Wiring" or equivalent.The labels shall be located so trinsic Safety. as to be visible after installation and placed so that they may be readily traced through the entire length of the in- (B) Associated Apparatus and Cable Shields.Associated stallation. Intrinsic safety circuit labels shall appear in ev- apparatus and cable shields shall be grounded in accor- a section t the wiring dance with the required control drawing. Seta 504.10(A). rY g system that is separated by enclo- sures, walls, partitions, or floors. Spacing between labels FPN: Supplementary connection(s) to the grounding elec- shall not be more than 7.5 m (25 ft). trode may be needed for some associated apparatus, for example, zener diode harriers, if specified in the control Exception: Circuits run underground shall be permitted to drawing. See ANSIIISA RP 12.06.01-2003, Wiring Meth- be identified where they become accessible after emergence ads for Hazardous (Classified) Locations Instrumentation from the ground. —Part 1:Intrinsic Safety. FPN No. 1: Wiring methods permitted in unclassified loca- (C) Connection to Grounding Electrodes. Where con- lions may be used for intrinsically safe systems in hazard- nection to a grounding electrode is required, the grounding ous (classified) locations. Without labels to identify the 2008 Edition NATIONAL ELECTRICAL CODE 70-383 505.1 ARTICLE 505—CLASS I.ZONE 0, 1,AND 2 LOCATIONS application of the wiring, enforcement authorities cannot ment, could potentially become an ignition source in haz- determine that an installation is in compliance with this ardous (classified) locations. Code. e Encapsulation "m." Type of protection where electrical FPN No. In unclassified locations, identification is parts that could ignite an explosive atmosphere by either essary to ensure that nonintrinsically safe wire will not t be be inadvertently added to existing raceways at a later date. sparking or heating are enclosed in a compound in such a way that this explosive atmosphere cannot be ignited. (C) Color Coding. Color coding shall be permitted to FPN No. 1: See ANSI/ISA-60079-18 (12.23.01)-2005, identify intrinsically safe conductors where they are col- Electrical Apparatus for Use in Class 1, Zone I Hazardous ored light blue and where no other conductors colored light (Classified)Locations, Type of Protection—Encapsulation blue are used. Likewise, color coding shall be permitted to "inn"; IJEC 60079-18-1992, Electrical apparatus for explo- identify raceways, cable trays, and junction boxes where save gas atmospheres—Part 18: Encapsulation "rn"; and ANSUU,L, 60079-18, Electrical Apparatus for Explosive they are colored light blue and contain only intrinsically Gas Atmospheres—Part 18.Encapsulation "m". safe wiring. FPN No,2: Encapsulation is designated type of protection "ma" for use in Zone 0 locations. Encapsulation is desig- nated type of protection "trt" or"mb" for use in Zone I locations. ARTICLE 505 Flameproof "d." Type of protection where the enclosure Class 1, Zone 0, 1, and 2 Locations will withstand an internal explosion of a flammable mixture that has penetrated into the interior, without suffering dam- age and without causing ignition, through any joints or FPN: Rules that are followed by a reference in brackets structural openings in the enclosure, of an external explo- contain text that has been extracted from NFPA 497-2004, sive gas atmosphere consisting of one or more of the gases Recommended Practice for the Classification of Flammable or vapors for which it is designed. Liquids, Gases, or Vapors and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process FPN: See ANSIASA-60079-1 (12.22.01)-2005, Electrical Areas. Only editorial changes were made to the extracted Apparatus for Use in Class I, pone 1 and 2 Hazardous(Clas- text to make it consistent with this Code. sified)Lcneations, Type of Protection—Flameproof"d";and ANSIIUL 60079-1, Electrical Apparatus for Explosive Gas 505.1 Scope. This article covers the requirements for the Atmospheres—Part 1: Flamepmof Enclosures °d." zone classification system as an alternative to the division Increased Safety "e." Type of protection applied to elec- classification system covered in Article 500 for electrical trical equipment that does not produce arcs or sparks in and electronic equipment and wiring for all voltages in normal service and under specified abnormal conditions, in Class 1. Zone 0, Zone 1, and Zone 2 hazardous (classified) which additional measures are applied so as to give in- locations where fire or explosion hazards may exist due to creased security against the possibility of excessive tem- flammable gases, vapors, or liquids. peratures and of the occurrence of arcs and sparks. FPN: For the requirements for electrical and electronic FPN: See ANSI/ISA-60079-7 (12.16.01)-2002, Electrical equipment and wiring for all voltages in Class I, Division l Apparatus for Use in Class 1, Zone 1 Hazardous (Classi- or Division 2; Class II, Division 1 or Division 2; and Class fled)Locations, Tape of Protection—Increased Safety "e"; 111, Division 1 or Division 2 hazardous (classified) loca- and ANSIIUL 60079-7, Electrical Apparatus for Explosive tions where fire or explosion hazards may exist due to flam- Gas Atmospheres---Part 7: Increased Safety "e." mable gases or vapors, flammable liquids, or combustible Intrinsic Safety"i."Type of protection where any spark or dusts or fibers, refer to Articles 500 through 504. thermal effect is incapable of causing ignition of a mixture 505.2 Definitions. For purposes of this article, the follow- of flammable or combustible material in air under pre- ing definitions apply. scribed test conditions. FPN No. 1: See ANSULIL 913-1997,Intrinsically Safe Ap- Combustible Gas Detection System. A protection tech- paratus and Associated Apparatus for Use in Class 1, 11, nique utilizing stationary gas detectors in industrial estab- and 171, Hazardous Locations; ANSUISA-60079-11 lishments. (12.02.01)-2002, Electrical Apparatus for Use in Class 1, Zones 0, l and 2 Hazardous (Classified) Locations— In- Electrical and Electronic Equipment. Materials, fittings, trinsic Safety "t"'; and ANSWUL 60079-11, Electrical Ap- devices, appliances, and the like that are part of, or in paratus for Explosive Gas Atmospheres—Part 11.Intrinsic connection with, an electrical installation. Safely "i." FPN No.2: Intrinsic safety is designated type of protection FPN: Portable or transportable equipment having self- "ia" for use in Zone 0 locations. Intrinsic safety is desig- contained power supplies, such as battery-operated equip- nated type of protection "ib" for use in Zone I locations. 70-384 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 505-CLASS 1,ZONE 0, 1,AND 2 LOCATIONS 565.4 FPN No. 3: Intrinsically safe associated apparatus, desig- Exception: As modified by Article 504 and this article. nated by [ia] or [ib], is connected to intrinsically safe ap- paratus("ia"or"ib,"respectively)but is located outside the hazardous (classified) location unless also protected by an- 505.4 General. other type of protection (such as flameproof). (A) Documentation for Industrial Occupancies. All ar- Oil Immersion "o." Type of protection where electrical eas in industrial occupancies designated as hazardous(clas- equipment is immersed in a protective liquid in such a way sified) locations shall be properly documented. This docu- that an explosive atmosphere that may be above the liquid mentation shall be available to those authorized to design, or outside the enclosure cannot be ignited, install, inspect, maintain, or operate electrical equipment at FPN: See ANST/ISA-60079-6 (12.26.01)-1998, Electrical the location. Apparatus far Use in Class 1, Zone 1 Hazardous (Classi- fied) Locations, Tape of Protection - Oi!-Immersion "n"; FPN: For examples of area classification drawings, see and ANSI/UL 60079-6, Electrical Apparatus for•lion ".is,c, ANSI/API RP 505-1997, Recommended Practice for Clas- Gas Atmospheres-Part 6: rival mnersinrn "o." sif cation of Locations for Electrical Installations at Petro- leum Facilities Classified as Class 1, Zone 0, Zone 1, or Powder Filling "q." Type of protection where electrical Zone 2, ANSI/ISA-TR (12.24.01)-1998 (IEC 60079-10 Mod),Recommended Practice for Classification of Loc•atiorts parts capable of igniting an explosive atmosphere are fixed for Electrical Installations Classified as Class I,,Zone 0,Ztme in position and completely surrounded by filling material 1, or Zone 2, IEC 60079-10-1995, Electrical Apparatus for (glass or quartz powder) to prevent the ignition of an ex- Explosive Gas Atmospheres, Classification of Hazardous Ar- terna] explosive atmosphere. eas,and Model Code of Safe Practice in the Petroleum hndus- tr, Part 15:Area Classification Cmle for Petroleum Insialla- FPN: See ANSUISA-60079-5 (12.25.01)-1998, Electrical tuns, IP 15,The Institute of Petroleum.London. Apparatus for Use in Class 1, Zane I Hazardous (Classi- fied) Locations Tv7,e of Protection - Powder Filling °q',: (B) Reference Standards. Important information relat- and ANSIIUL 60079-5, Electrical Apparatus,for Explosive ing to topics covered in Chapter 5 may be found in other Gas Atmospheres-Part 5: Powder Filling °q." publications. Pressurization"p."Type of protection for electrical equip- FPN No. 1: It is important that the authority having luris ment that uses the technique of guarding against the ingress diction be familiar with recorded industrial experience as of the external atmosphere, which may be explosive, into well as with standards of the National Fire Protection As- an enclosure by maintaining a protective gas therein at a soc:iation (NFPA), the American Petroleum Institute (API), pressure above that of the external atmosphere, the Instrumentation, Systems, and Automation Society 0SA), and the International Electrotechnical Commission FPN: See ANSVISA-60079-2 (12.04.01)-2004, Electrical (IEC) that may be of use in the classification of various Apparatus for Explosive Gas Atm ospheres- Part 2:Pres- locations,the determination or adequate ventilation,and the surized Enclosures "p", and IEC 60079-13-1982, Elec•tri- protection against static electricity and lightning hazards. ctrl apparatus for explosive gas atmospheres - Part 13: FPN No. 2: For further information on the classification of Construction and use of roonis or buildings protected by locations, see ANSUAPI RP 505-1997, Recommended pressurization. Practice for Classification of Locations for Electrical In- Type of Protection "n." Type of protection where electri- stallations at Petroleum Facilities Classified as Class I. cal equipment, in normal operation, is not capable of ignit- Zone 0, Zone 1, or Zone 2;ANSI/ISA-TR(12.24.01)-1998 (IEC 60079-10 Mod), Recommended Practice for Classifi. ing a surrounding explosive gas atmosphere and a fault cation of Locations for Electrical Installations Classified as capable of causing ignition is not likely to occur. Class 1, Zane 0, Zane 1, or Zane 2, IEC 60079-10-1995, Electrical Apparatus for Explosive Gas Atmospheres, Clas- FPN: See ANSUUL 60079-15-2002, Electrical Apparatus sfication of Hn ardous Areas; and Model Code of Safe for Explosive Gas Atmospheres-Part 15: 7i'pe of Protec•- Practice in the Petroleum Industry, Part 15:Area Classifi- tion "it"-, and ANSUISA 60079-15 (12.12.02)-2003, Elec- cation Code for Petroleum Installations, IP 15, The Insti- tric•al Apparatus for Use in Class 1, Zane 2 Hazardous tute of Petroleum. London. (Classified)Locations: Type of Protection "n." FPN No. 3: For further information on protection against Unclassified Locations.Locations determined to be neither static electricity and lightning hazards in hazardous (classi- Class I, Division 1, Class 1, Division 2; Class I, Zone 0; fled) locations,see NFPA 77-2007,Recommended Practice Class 1, Zone 1; Class 1, Zone 2; Class 1I, Division 1; Class on Static Electricity; NFPA 780-2004,Standard for the In- stallation of Lightning Protection Systems; and APT RP II,Division 2;Class III,Division 1;Class III, Division 2;or 2003-1998, Protection Against Ignitions Arising Out of any combination thereof. Static Lightning and Stray Currents. 505.3 Other Articles. All other applicable rules contained FPN No. 4: For further information on ventilation, see NFPA 30-2007,Flammable and Combustible Liquids Code, in this Code shall apply to electrical equipment and wiring and ANSI/API RP 505-1997, Recommender) Practice./or installed in hazardous (classified) locations. Classification of Locations for Electrical Installations at 2008 Edition NATIONAL ELECTRICAL CODE 70-385 505,5 ARTICLE 505--CLASS 1,ZONE 0, 1,AND 2 LOCATIONS Petroleum Facilities Classified as Class 1, Zone 0, Zane 1, cient to produce explosive or ignitible mixtures. Class I, or Zone 2, Zone 0, 1, and 2 locations shall include those specified in FPN No. 5: For further information on electrical systems 505(B)(1), (B)(2), and (13)(3). for hazardous (classified) locations on offshore oil and gas producing platforms, see ANSUAPI RP 14FZ-2000, Ree- (1) Class I, Zone 0. A Class 1, .Zone 0 location is a loca- ommended Practice for Design and Installation of Elec'tri- tion in which cal Systems for Fixed and Floating Offshore Petroleum Fa- (1) Ignitible concentrations of flammable gases or vapors cilities for Unclassified and Class 1, Zone 0, Zone 1, and Zone 2 Locations. are present continuously, or FPN No. 6: For further information on the installation of (2) Ignitible concentrations of flammable gases or vapors electrical equipment in hazardous (classified) locations in are present for long periods of time. general, see IEC 60079-14-1996, Electrical apparatus for explosive gas atmospheres-Part 14: Electrical installs- FPN No. 1: As a guide in determining when flammable tions in explosive gas atmospheres(other than mines),and gases or vapors are present continuously or for long periods IEC 60079-16-1990,Electrical apparatus for explosive gas of time, refer to ANSUAPI RP 505-1997, Recommended atmospheres - Part 16:Artificial ventilation for the pro- Practice for Classification of Locations for Electrical In- tection of analyzer(s)houses. stallations of Petroleum Facilities Classified as Class I, Zone 0, Zone I or Zone 2; ANSUISA-VISA 12.2[4.01-1998 FPN No.7: For further information on application of elec- trical equipment in hazardous (classified) locations in gen- (IBC fi0079-Ip lvltxl), Recommended Practice for Clussifi- eral, see ANSIIZSA 600dous (12.00.00-2005,lass ed Electrical cation of Locations for Electrical Installations Classified as Class 1, Zone 0, Zone 1, or Zane 2; IEC 60079-10-1995, Apparatus for Use in Class 1, Zones 0 and 1, Hazardous Electrical apparatus for explosive gas atmospheres, classi- (Classified) Locations: General Requirements; ANSUISA- fications of hazardous areas; and Area Classification Code 12.01.01-1999, Definitions and Information Pertaining to Electrical Apparatus in Hazardous (Classified) Locations; for Petroleum Installations, Model Code, Part IS, Institute and ANSI/UL 60079-0, Electrical Apparatus for Explosive of Petroleum. Gas Atmospheres- Part 0: General Requirements. FPN No. 2: This classification includes locations inside vented tanks or vessels that contain volatile flammable liq- 505.5 Classifications of Locations. uids; inside inadequately vented spraying or coating enclo- sures,where volatile flammable solvents are used;between (A) Classification of Locations. Locations shall be classi- the inner and outer roof sections of a floating roof tank fied depending on the properties of the flammable vapors, containing volatile flammable liquids; inside open vessels, liquids, or gases that may be present and the likelihood that tanks and pits containing volatile flammable liquids; the a flammable or combustible concentration or quantity is interior of an exhaust duct that is used to vent ignitible concentrations of gases or vapors; and inside inadequately present. Where pyrophoric materials are the only materials ventilated enclosures that contain normally venting instru- used or handled, these locations shall not be classified. ments utilizing or analyzing flammable fluids and venting Each room, section, or area shall be considered individually to the inside of the enclosures. in determining its classification. FPN No. 3: It is not good practice to install electrical FPN No. 1: See 505.7 for restrictions on area equipment in Zone 0 locations except when the equipment classification, is essential to the process or when other locations are not feasible. [See 505.5(A) FPN No. 2.1 If it is necessary to FPN No.2: Through the exercise of ingenuity in the layout install electrical systems in a Zone 0 location, it is good of electrical installations for hazardous (classified) loca- practice to install intrinsically safe systems as described by tions, it is frequently possible to locate much of the equip- Article 504. ment in reduced level of classification or in an unclassified location and, thus, to reduce the amount of special equip- (2) Class I, Zone 1. A Class I,Zone 1 location is a location ment required. (1) In which ignitible concentrations of flammable gases or Rooms and areas containing ammonia refrigeration sys- vapors are likely to exist under normal operating con- tems that are equipped with adequate mechanical ventila- ditions; or tion may be classified as "unclassified" locations. (2) In which ignitible concentrations of flammable gases or FPN: For further information regarding classification and vapors may exist frequently because of repair or main- ventilation of areas involving ammonia, see ANSI/ tenance operations or because of leakage; or ASHRAE 15-1994,Safety Code for Mechanical Refrigera- (3) In which equipment is operated or processes are carried lion; and ANSI/CGA G2.1-1989 (14-39), Safety Require- on, of such a nature that equipment breakdown or ments for the Storage and Handling of Anhydrous faulty operations could result in the release of ignitible Ammonia. concentrations of flammable gases or vapors and also (B) Class 1, Zone 0, 1, and 2 Locations. Class I, Zone 0, cause simultaneous failure of electrical equipment in a 1, and 2 locations are those in which flammable gases or mode to cause the electrical equipment to become a vapors are or may be present in the air in quantities suffi- source of ignition; or 70-396 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 505—CLASS 1.ZONE 0, 1,AND 2 LOCATIONS 505.6 (4) That is adjacent to a Class I, Zone 0 location from FPN: The Zone 2 classification usually includes locations which ignitible concentrations of vapors could be com- where volatile flammable liquids or flammable gases or municated, unless communication is prevented by ad- vapors are used but which would hecome hazardous only in equate positive pressure ventilation from a source of case of an accident or of some unusual operating condition. clean air and effective safeguards against ventilation 505,6 Material Groups. For purposes of testing, approval, failure are provided. and area classification, various air mixtures (not oxygen en- FPN No. 1: Normal operation is considered the situation riched)shall be grouped as required in 505.6(A),(B),and(C). when plant equipment is operating within its design param- eters. Minor releases of flammable material may be part of FPN: Group 1 is intended for use in describing atmo- normal operations. Minor releases include the releases from spheres that contain firedamp (a mixture of gases, com- mechanical packings on pumps. Failures that involve repair posed mostly of methane, found underground, usually in or shutdown (such as the breakdown of pump seals and mines). This Code does not apply to installations under- flange gaskets, and spillage caused by accidents) are not ground in mines. See 90.2(8). considered normal operation. Group II shall be subdivided into IIC, IIB, and IIA, as FPN No. 2: This classification usually includes locations noted in 505.6(A), (B), and (C), according o the nature of where volatile flammable liquids or liquefied flammable g gases are transferred from one container to another.In areas the gas or vapor, for protection techniques "d," "ia," "ib," in the vicinity of spraying and painting operations where "[ia]," and "[ib]," and, where applicable, "n" and "o." flammable solvents are used; adequately ventilated drying rooms or compartments for evaporation of flammable sol- FPN No. l: The gas and vapor subdivision as described vents:adequately ventilated locations containing fat and oil above is based on the maximum experimental safe gap extraction equipment using volatile flammable solvents; (MESG), minimum igniting current (MIC), or both. Test portions of cleaning and dyeing plants where volatile flam- equipment for determining the MESG is described in IEC mable liquids are used; adequately ventilated gas generator 60079-IA-1975, Amendment No. 1 (1993), Construction rooms and other portions of gas manufacturing plants and verification tests of flameproof enclosures of electrical where flammable gas may escape; inadequately ventilated apparatus,. and UL Technical Report No. 58 (1993). The pump rooms for flammable gas or for volatile flammable test equipment for determining MIC is described in IEC liquids; the interiors of refrigerators and freezers in which 6(X)79-11-1999, Electrical apparatus for explosive gas at- volatile flammable materials are stored in the open, lightly ntospheres — Part 11: Intrinsic safety "i." The classifica- stoppered, or in easily ruptured containers: and other loca- tion of gases or vapors according to their maximum experi- tions where ignitible concentrations of flammable vapors or mental safe gaps and minimum igniting currents is IEC 600 n 79-1 2-1 97 8, Classi f ication o f mixtures gases are likely to occur in the course of norms[ operation described but not classified Zone 0. of gases or vapours with air according to their maxitman experimental.safe gaps and minimtan igniting currents. (3) Class I, Zone Z. A Class I, Zone 2 location is a location FPN No. 2: Verification of electrical equipment utilizing (I) In which ignitible concentrations of flammable gases or protection techniques "e," "m,""p,"and"q,"due to design vapors are not likely to occur in normal operation and, technique, does not require tests involving MESG or MIC, if they do occur, will exist only for a short period; or Therefore, Group II is not required to be subdivided for (2) In which volatile flammable liquids, flammable gases, these protection techniques. or flammable vapors are handled, processed, or used FPN No. 3: It is necessary that the meanings of the differ- ent equipment markings and Group II classifications be but in which the liquids, gases, or vapors normally are carefully observed to avoid confusion with Class I, Divi- confined within closed containers of closed systems sions 1 and 2, Groups A, B, C, and D. from which they can escape, only as a result of acci- dental rupture or breakdown of the containers or sys- Class I, Zone 0, 1, and 2, groups shall be as follows: tem, or as a result of the abnormal operation of the equipment with which the liquids or gases are handled, (A) Group TIC. Atmospheres containing acetylene, hydro- equipment or flammable gas, flammable liquid–produced vapor, processed, or used; or or combustible liquid–produced vapor mixed with air that (3) In which ignitible concentrations of flammable gases or may burn or explode,having either a maximum experimen- vapors normally are prevented by positive mechanical tal safe gap (MESG)value less than or equal to 0.50 mm or ventilation but which may become hazardous as a re- minimum igniting current ratio (MIC ratio) less than or sult of failure or abnormal operation of the ventilation equal to 0.45. [497:3.3.5.2.1] equipment; or FPN: Group IIC is equivalent to a combination of Class 1, (4) That is adjacent to a Class [, Zone I location, from Group A,and Class I,Group B,as described in 500.6{A)(I) which ignitible concentrations of flammable gases or and (A)(2). vapors could be communicated, unless such communi- cation is prevented by adequate positive-pressure ven- (B) Group IIB. Atmospheres containing acetaldehyde, tilation from a source of clean air and effective safe- ethylene, or flammable gas, flammable liquid–produced va- guards against ventilation failure are provided. por, or combustible liquid–produced vapor mixed with air 2008 Edition NATIONAL ELECTRICAL CODE 70_387 S05.7 ARTICLE 505--CLASS I.ZONE 0, I,AND 2 LOCATIONS that may burn or explode, having either maximum experi- any solid obstacle that is not a part of the equipment(such mental safe gap (MESG) values greater than 0.50 mm and as steelworks, walls, weather guards, mounting brackets, less than or equal to 0.90 mm or minimum igniting current pipes, or other electrical equipment) unless the equipment ratio(MIC ratio) greater than 0.45 and less than or equal to is listed for a smaller distance of separation. 0.80. [497:3.3.5.2.21 Table 505.7(D) Minimum Distance of Obstructions from FPN: Group IIB is equivalent to Class 1, Group C, as de- Flameproof"d" Flange Openings scribed in 500.6(A)(3). (C) Group IIA. Atmospheres containing acetone, ammo- Minimum Distance nia, ethyl alcohol, gasoline, methane, propane, or flam- mable gas, flammable liquid-produced vapor, or combus- tible liquid-produced vapor mixed with air that may burn IIC 40 .17/(A or or explode, having either a maximum experimental safe 1113 30 Y1 t' gap (MESG) value greater than 0.90 mm or minimum ig- IIA 10 25/' niting current ratio (MIC ratio) greater than 0.80. [497:3.3.5.2.3] 505.8 Protection Techniques. Acceptable protection tech- FPN: Group 11A is equivalent to Class 1, Group D as de- niques for electrical and electronic equipment in hazardous scribed in 500.6(A)(4). (classified) locations shall be as described in 505.8(A) through (K). 505.7 Special Precaution. Article 505 requires equipment FPN: For additional information, see ANSMA-60079-0 construction and installation that ensures safe performance {12.00.01)-2005, Electrical Apparatus for Use in Class 1, under conditions of proper use and maintenance, Zones 0 and I Hazardous (Classified) Locations, General Requirements; ANSUISA-12.01.01-1999, Definitions and FPN No. 1: It is important that inspection authorities and Information Pertaining to Electrical Apparatus in Hazard- users exercise more than ordinary care with regard to the ous(Classified)Locations;and ANSVUL 60079-0,Electri- installation and maintenance of electrical equipment in haz- cal Apparatus for Explosive Gas Atmospheres — Part 0: ardous (classified) locations. General Requirements. FPN No. 2: Low ambient conditions require special con- "d". sideration. Electrical equipment depending on the protec- tion techniques described by 505.8(A) may not be suitable mitted for equipment in Class I, Zone 1 or Zone 2 locations. for use at temperatures lower than --20°C (--4°F) unless they are identified for use at lower temperatures. However, (B) Purged and Pressurized. This protection technique at low ambient temperatures, flammable concentrations of shall be permitted for equipment in those Class I,Zone I or vapors may not exist in a location classified Class I,Zones Zone 2 locations for which it is identified. 0, I, or 2 at normal ambient temperature. (A) Implementation of Zone Classification System. (C) Intrinsic Safety. This protection technique shall be p permitted for apparatus and associated apparatus in Class I, Classification of areas,engineering and design, selection of Zone 0, Zone 1, or Zone 2 locations for which it is listed. equipment and wiring methods,installation,and inspection shall be performed by qualified persons. (D) Type of Protection "n". This protection technique shall be permitted for equipment in Class I, Zone 2 loca- (B) Dual Classification. In instances of areas within the tions.Type of protection "n" is further subdivided into nA, same facility classified separately, Class 1, Zone 2 locations nC, and nR. shall be permitted to abut,but not overlap, Class I,Division 2 locations. Class I, Zone 0 or Zone 1 locations shall not FPN: See Table 505.9(C)(2)(4)of protection for the descriptions of sub- divisions for type of protection "n". abut Class I, Division 1 or Division 2 locations. (C) Reclassification Permitted. A Class I, Division 1 or (E) Oil Immersion "o". This protection technique shall Division 2 location shall be permitted to be reclassified as a be permitted for equipment in Class 1, Zone I or Zone 2 locations. Class I, Zone 0, Zone 1, or Zone 2 location,provided all of the space that is classified because of a single flammable (F) Increased Safety "e". This protection technique shall gas or vapor source is reclassified under the requirements be permitted for equipment in Class I, Zone 1 or Zone 2 of this article. locations. (D) Solid Obstacles. Flameproof equipment with flanged (G) Encapsulation "m". This protection technique shall joints shall not be installed such that the flange openings be permitted for equipment in Class 1, Zone I or Zone 2 are closer than the distances shown in Table 505.7(D) to locations. 70-388 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 505—CLASS 1,ZONE 0, 1,AND 2 LOCATIONS 505.9 (H) Encapsulation "ma". This protection technique shall 505.9 Equipment, be permitted for equipment in Class I, Zone 0, Zone 1, or Zone 2 locations. (A) Suitability.Suitability of identified equipment shall be determined by one of the following: (I) Encapsulation "mb". This protection technique shall (1) Equipment listing or labeling be permitted for equipment in Class I, Zone I or Zone 2 (2) Evidence of equipment evaluation from a qualified test- locations. ing laboratory or inspection agency concerned with product evaluation (J) Powder Filling "q". This protection technique shall {3} Evidence acceptable to the authority having jurisdiction locations.permitted for equipment in Class 1, Zone 1 or Zone 2 such as a manufacturer's self-evaluation or an owner's lo engineering judgment (K) Combustible Gas Detection System. A combustible FPN: Additional documentation for equipment may in- gas detection system shall be permitted as a means of pro- elude certificates demonstrating compliance with applicable tection in industrial establishments with restricted public equipment standards, indicating special conditions of use, access and where the conditions of maintenance and super- and other pertinent information. vision ensure that only qualified persons service the instal- (B) Listing. lation, Where such a system is installed, equipment speci- (1) Equipment that is listed for a Zone 0 location shall be fied in 505.8(K)(1), K(2). or K(3) shall be permitted. The permitted in a Zone l or Zone 2 location of the same type of detection equipment, its listing, installation loci- gas or vapor, provided that it is installed in accordance tion(s), alarm and shutdown criteria, and calibration fre- with the requirements for the marked type of protec- quency shall be documented when combustible gas detec- tion.Equipment that is listed for a Zone I location shall tors are used as a protection technique. be permitted in a Zone 2 location of the same gas or FPN No. l: For further information, see ANSUAPI RP vapor, provided that it is installed in accordance with 505,Recommended Practice for Classifirurinn of Iw)c,taions the requirements for the marked type of protection. for Electrical Installations tit Petroleum Facilities Clussi- (2) Equipment shall be permitted to be listed for a specific fied as Class 1, Zone 0, Zone 1, and 'Zone 2. gas or vapor, specific mixtures of gases or vapors, or FPN No. 2: For Further information, see ISA-RP12.13.02- any specific combination of gases or vapors, 2003 (1EC 61779-6 Mod), Installation, Operation, and FPN: One common example is equipment marked for 1113, Maintenance of Combustible Gus Detection Instruments. + H2." (1) Inadequate Ventilation. In a Class I, Zone 1 location (C) Marking. Equipment shall be marked in accordance that is so classitied due to inadequate ventilation, electrical with 505.9(C)(1) or (C)(2), equipment suitable for Class 1, Zone 2 locations shall be permitted. Combustible gas detection equipment shall be (1) Division Equipment. Equipment identified for Class 1, listed for Class I, Zone 1, for the appropriate material Division 1 or Class 1, Division 2 shall, in addition to being group, and for the detection of the specific gas or vapor to marked in accordance with 500.8(C), be permitted to be be encountered. marked with all of the following: (2) Interior of a Building. In a building located in,or with (1) Class 1, Zone 1 or Class I, Zone 2 (as applicable) an opening into, a Class I, Zone 2 location where the inte- (2) Applicable gas classification group(s) in accordance rior does not contain a source of flammable gas or vapor, With Table 505.9(0)(1)(2) electrical equipment for unclassified locations shall be per- (3) Temperature classification in accordance with mitted. Cornbustible gas detection equipment shall be listed 505.9(D)(1) for Class I,Zone I or Class I, Zone 2, for the appropriate Table 505.9(C)(1)(2) Gas Classification Groups material group, and for the detection of the speci=fic gas or vapor to be encountered. Gas Group Comment (3) Interior of a Control Panel. In the interior of a control I1C See 505.6(A) panel containing instrumentation utilizing or measuring IIB See 505.6(10 flammable liquids, gases, or vapors, electrical equipment IIA See 505.6(C) suitable for Class 1, Zone 2 locations shall he permitted. Combustible gas detection equipment shall be listed for (2) Zone Equipment. Equipment meeting one or more of Class I,Zone 1,for the appropriate material group, and for the protection techniques described in 505.8 shall be the detection of the specific gas or vapor to be encountered. marked with all of the following in the order shown: 2 00g Edition NATIONAL ELECTRICAL CODE 70-389 505.9 ARTICLE 505—CLASS I,ZONE 0, 1,AND 2 LOCATIONS (1) Class Example: Class I Zone 0 AEx la IIC T6 (2) Zone Area classification (3) Symbol "AEx" Symbol(4) Protection technique(s) in accordance with Table standards r equipment built to American 505.9(C)(2)(4) Type(s)of protection designation (5) Applicable gas classification group(s) in accordance with Table 505.9(C)(1)(2) Gas classification group(not required for protection techniques indicated in 505.6, FPN No.2) (6) Temperature classification in accordance with Temperature classification Exception No. 1: Associated apparatus NOT suitable for FPN Figure 505.9(C)(2) Zone Equipment Marking. installation in a hazardous (classified) location shall be required to be marked only with(3), (4), and(5), but BOTH Table 505.9(C)(2)(4) Types of Protection Designation the sYnbol AEx (3) and the symbol for the type of protec- tion (4) shall be enclosed within the same square brackets, Designation Technique Zone* for example, [AEx ia] IIC. d Flameproof enclosure Exception No. 2: Simple apparatus as defined in 504.2 a Increased safety shall not be required to have a marked operating tempera- is Intrinsic safety 0 ib Intrinsic safety 1 tore or temperature class. [ia] Associated apparatus Unclassified** Electrical equipment of types of protection "e," "m," [ib] Associated apparatus Unclassified** "ma," "mb," "px," "p ma .Ey," "pz," or "q" shall be marked m Encapsulation ncapsulation Q Group 11. Electrical equipment of types of protection "d," mb Encapsulation 1 "ia," "ib," "[ia]," or"[ib]" shall be marked Group IIA, IIB, nA Nonsparking 2 or IIC, or for a specific gas or vapor. Electrical equipment equipment oft es of protection "n" shall be marked Group 11 unless nC Sparking equipment in 2 YP P P which the contacts are it contains enclosed-break devices, nonincendive compo- suitably protected nents, or energy-limited equipment or circuits, in which other than by restricted case it shall be marked Group IIA, IIB, or IIC, or a specific breathing enclosure gas or vapor. Electrical equipment of other types of protec- nR Restricted breathing 2 enclosure tion shall be marked Group Ii unless the type of protection o Oil immersion 1 utilized by the equipment requires that it be marked Group px Pressurization 1 IIA, IIB, or IIC, or a specific gas or vapor. pY Pressurization l pz Pressurization 2 FPN No. 1: An example of the required marking for intrin- q Powder filled 1 sically safe apparatus for installafion in Class 1, Zone 0 is "Class I,Zone 0,AEx is TIC T6."An explanation of the mark- *Does not address use where a combination of techniques is used. ing that is required is shown in FPN Figure 505.9(C)(2). **Associated apparatus is permitted to be installed in a hazardous (classified)location if suitably protected using another type ofprotec- FPN No.2: An example of the required marking for intrin- tion. sically safe associated apparatus mounted in a Flameproof enclosure for installation in Class 1, Zone l is "Class I, Gas Atmospheres,Data for Flammable Gases and Vapours, Zone 1 AEx d[ia] IIC T4." Relating to the Use of Electrical Apparatus. FPN No.3: An example of the required marking for intrin- (1) Temperature Classifications. Equipment shall be sically safe associated apparatus NOT for installation in a marked to show the operating temperature or temperature hazardous (classified) location is "[AEx ia] IIC." class referenced to a 40°C (104°F) ambient. The tempera- (D) Class I Temperature.The temperature marking speci- ture class, if provided, shall be indicated using the tempera- fied below shall not exceed the ignition temperature of the ture class (T Code) shown in Table 505.9(D)(1). specific gas or vapor to be encountered. Electrical equipment designed for use on the ambient temperature range between --20 C and +40'C shall require FPN: For information regarding ignition temperatures of no additional ambient temperature marking. gases and vapors, see NFPA 497-2004, Recommended Electrical equipment that is designed for use in a range Practice for the Classification of Flammable Liquids, Gases, or Vapors and of Hazardous(Classified) Locations of ambient temperatures other than—20°C to+40°C is con- for Electrical Installations in Chemical Process Areas,and sidered to be special; and the ambient temperature range IEC 60079-20-1996, Electrical Apparatus for Explosive shall then be marked on the equipment, including either the 70--390 NATIONAL ELECTRICAL CODs; 2009 Edition ART]CLE 505—CLASS I,ZONE 0, 1.AND 2 LOCATIONS 505.15 Table 505.9(D)(1) Classification of Maximum Surface (2) Equipment Provided with Threaded Entries for Temperature for Group II Electrical Equipment Metric Threaded Conduit or Fittings. For equipment with metric threaded entries, such entries shall be identified Temperature Class Maximum Surface as being metric, or listed adapters to permit connection to {T Code) Temperature ('C) conduit or NPT-threaded fittings shall be provided with the T1 5450 equipment. Adapters shall be used for connection to con- T2 :000 duit or NPT-threaded fittings. Listed cable fittings that have T3 5200 metric threads shall be permitted to be used. T4 5135 T5 :-100 FPN: Threading specifications for metric threaded entries T6 585 are located in ISO 965/1-1980.Metric Screw Threads;and ISO 965/3-1980, Metric Screw Threads. symbol "Ta" or "Tamb" together with the special range of (F) Fiber Optic Cable Assembly.Where a fiber optic cable ambient temperatures, in degrees Celsius. assembly contains conductors that are capable of carrying cur- Electrical equipment suitable for ambient temperatures rent,the fiber optic cable assembly shall be installed in accor- exceeding 40°C (104°F) shall be marked with both the dance with 505.15 and 505.16, as applicable. maximum ambient temperature and the operating tempera- ture or temperature class at that ambient temperature. 505.15 Wiring Methods. Wiring methods shall maintain FPN: As an example, such a marking might be"--30°C to the integrity of protection techniques and shall comply with +400C." 505.15(A) through (C). Exception No. 1: Equipment of the non-heat-producing (A) Class I, Zone 0. In Class I, Zone 0 locations, only type, such as conduit fittings, and equipment of the heat- intrinsically safe wiring methods in accordance with Article producing type having a maxittuon temperature of not more 504 shall be permitted. than 100°C(2127)shall not be required to have a marked FPN: Article 504 only includes protection technique "ia." operating temperature or temperature class. Exception No. 2: Equipment identified for Class 1, Division (B) Class 1, Zone 1. I or Division 2 locations as permitted br 505.20(B) and (D) shall he permitted to be marked in accordance with (1) General. In Crass I, Zone 1 Iocations, the wiring meth- 500.8(C) and Table 500.8(C). ods in (13)(1)(a) through (B)(1)(f) shall be permitted. (a) All wiring methods permitted by 505.15(A). (E) Threading. All NPT threaded conduit and fittings re- (b) In industrial establishments with restricted public ferred to herein shall be threaded with a National (Ameri- access, where the conditions of maintenance and supervi- can)Standard Pipe Taper(NPT) thread that provides a taper Sion ensure that only qualified persons service the installa- of 1 in 16 (.1/4-in, taper per foot). Conduit and fittings shall tion, and where the cable is not subject to physical damage, be made wrenchtighl to prevent sparking when fault current Type MC-HL cable listed for use in Class I, Zone 1 or flows through the conduit system, and to ensure the explo- Division 1 locations, with a gas/vaportight continuous cor- sionproof or flameproof integrity of the conduit system rugated metallic sheath, an overall jacket of suitable poly- where applicable, Equipment provided with threaded en- meric material, a separate equipment grounding conduc- tries for field wiring connections shall be installed in accor- tor(s) in accordance with 250.122, and provided with dance with 505.9(E)(1) or (E)(2). Threaded entries into ex- termination fittings listed for the application. plosionproof or flameproof equipment shall be made up with at least five threads fully engaged. FPN: See 330.12 for restrictions on use of Type MC cable. Exception: For listed explosionproof or flameproof equip- (c) In industrial establishments with restricted public meat,fac•tory threaded NPT entries shall be made up with access, where the conditions of maintenance and supervi- at least 4th threads f tlh' engaged. sion ensure that only qualified persons service the installa- tion, and where the cable is not subject to physical damage, (1) Equipment Provided with Threaded Entries for Type ITC-HL cable, listed for use in Class 1, Zone 1 or NPT Threaded Conduit or Fittings. For equipment pro- Division 1 locations, with a gas/vaportight continuous cor- vided with threaded entries for NPT threaded conduit or rugated metallic sheath, an overall jacket of suitable poly- fittings, listed conduit fittings or cable fittings shall be used. meric material and provided with termination fittings listed FPN: Thread form specifications for NPT threads are lo- for the application. cated in ANSI/ASME 131.20.1-1983, Pipe Threads, Gen- FPN: See 727.4 and 727.5 for restrictions on use of Type eral Purpose(Inch). ITC Cable. 20[)8 Edition NATIONAL ELECTRICAL CODE 70-391 505.16 ARTICLE 505—CLASS I,ZONE 0, 1,AND 2 LOCATIONS (d) Type MI cable with termination fittings listed for tions. Nonincendive field wiring systems shall be installed Class I, Zone 1 or Division 1 locations.Type MI cable shall in accordance with the control drawing(s). Simple appara- be installed and supported in a manner to avoid tensile tus, not shown on the control drawing, shall be permitted in stress at the termination fittings. a nonincendive field wiring circuit, provided the simple (e) Threaded rigid metal conduit, or threaded steel in- apparatus does not interconnect the nonincendive field wir- termediate metal conduit. ing circuit to any other circuit. (f) Type PVC conduit and 7Iype,RTRC Conduit shall be permitted where encased in a concrete envelope a minimum FPN: Simple apparatus is defined in 5(]4.2. of 50 mm (2 in.) thick and provided with not less than Separate nonincendive field wiring circuits shall be in- 600 mm, (24 in.) of cover measured from the top of the stalled in accordance with one of the following: conduit to grade. Threaded rigid metal conduit or threaded (1) In separate cables steel intermediate metal conduit shall be used for the last 600 mm (24 in.) of the underground run to emergence or to (2) In multiconductor cables where the conductors of each the point of connection to the aboveground raceway. An circuit are within a grounded metal shield equipment grounding conductor shall be included to pro- (3) In multiconductor cables where the conductors of each vide for electrical continuity of the raceway system and for circuit have insulation with a minimum thickness of grounding of non--current-carrying metal parts. 0.25 mm (0.01 in.) (2) Flexible Connections. Where necessary to employ (2) Flexible Connections. Where provision must be made flexible connections, flexible Fittings listed for Class I,Zone for limited flexibility, flexible metal fittings, flexible metal 1 or Division 1 locations or flexible cord in accordance conduit with listed fittings, liquidtight flexible metal con- with the provisions of 505.17 shall be permitted. duit with listed fittings, liquidtight flexible nonmetallic con- duit with listed fittings, or flexible cord in accordance with (C} Class I, Zone 2. the provisions of 505.17 shall be permitted. (1) General. In Class 1,Zone 2 locations,the wiring meth- ods in (C)(1)(a) through (C)(1)(h) shall be permitted. FPN: See 505.25(B) for grounding requirements where flexible conduit is used. (a) All wiring methods permitted by 505.15(B). (b) Types Ml, MC, MV, or TC cable with termination 505.16 Sealing and Drainage. Seals in conduit and cable fittings, or in cable tray systems and installed in a manner systems shall comply with 505.16(A) through (E). Sealing to avoid tensile stress at the termination fittings. Single conductor Type MV cables shall be shielded or metallic- compound shall be used in Type MI cable termination fit- tings to exclude moisture and other fluids from the cable armored. insulation. (c) Type ITC cable as permitted in 727.4. (d) Type PLTC cable in accordance with the provisions FPN No. 1: Seals are provided in conduit and cable sys- of Article 725, or in cable tray systems. PLTC shall be tems to minimize the passage of gases and vapors and pre- installed in a manner to avoid tensile stress at the termina- vent the passage of flames from one portion of the electrical installation to another through the conduit. Such communi- cation through Type MI cable is inherently prevented by (e) Enclosed gasketed busways, enclosed gasketed construction of the cable. Unless specifically designed and wireways. tested for the purpose, conduit and cable seals are not in- (t) Threaded rigid metal conduit, threaded steel inter- tended to prevent the passage of liquids,gases,or vapors at mediate metal conduit. a continuous pressure differential across the seal. Even at differences in pressure across the seal equivalent to a few (g) in industrial establishments with restricted public inches of water, there may be a slow passage of gas or access where the conditions of maintenance and supervi- vapor through a seal and through conductors passing sion ensure that only qualified persons service the installa- through the seal. See 505.16(C)(2)(b). Temperature ex- tion and where metallic conduit does not provide sufficient tremes and highly corrosive liquids and vapors can affect corrosion resistance, reinforced thermosetting resin conduit the ability of seals to perform their intended function. See (RTRC),factory elbows,and associated fittings, all marked 505.16{D){2). with the suffix-XW,and Schedule 80 PVC conduit,factory FPN No. 2: Gas or vapor leakage and propagation of elbows, and associated fittings shall be permitted. Where flames may occur through the interstices between the Seals are required for boundary conditions as defined in strands of standard stranded conductors larger than 2 AWG. Special conductor constructions, for example, compacted 505.16(C)(1)(b), the Zone 1 Wiring method shall extend strands or sealing of the individual strands, are means of into the Zone 2 area to the seal, which shall be located on reducing leakage and preventing the propagation of flames. the Zone 2 side of the Zone 1—Zone 2 boundary. (h) Nonincendive field wiring shall be permitted using (A) Zone 0. In Class 1, Zone 0 Iocations, seals shall be any of the wiring methods permitted for unclassified loca- located according to 505.16(A)(1), (A)(2), and (A)(3). 70-392 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 505—CLASS 1,ZONE 0, 1.AND:.LOCATIONS 505.16 (1) Conduit Seals. Seals shall be provided within 3.05 m the autoignition temperature in degrees Celsius of the gas (10 ft) of where a conduit leaves a Zone 0 location. There or vapor involved. shall be no unions, couplings, boxes, or Fittings, except Exception: Conduit entering an enclosure where such listed reducers at the seal, in the conduit run between the switches, circuit breakeru,,fases, relaYs, or resistors c•otnphy seal and the point at which the conduit leaves the location. with one of the following: Exception: A rigid unbroken conduit that passes can- (1) Are enclosed within a chamber herinetic•ally sealed pletely through the Zone 0 location with no fittings less against the entrance of gases or vapors. than 300 nun (12 in.) bevond each boundary shall not be (2) Are immersed in oil. required to be sealed if the termination points of the unbro- ken conduit care in unclassified locations. (3) Are enclosed within a factory-sealed explosionproof chamber located within the enclosure, identified for the (2) Cable Seals. Seals shall be provided on cables at the location, and marked `factory sealed" or equivalent, first point of termination after entry into the Zone 0 unless the entr' is metric designator 53 (trade size 2) location. or larger: Fac•tor"v-sealed enclosures shall not be con- sidered to serve as a seal for another adjacent explo- (3) Not Required to Be Explosionproof or Flameproof. sionproof enclosure that is required to have a conduit Seals shall not be required to be explosionproof or flame- seal. proof. (b) Conduit seals shall be installed within 450 mm (B) Zone 1. In Class I, Zone I locations, seals shall be (18 in.) from the enclosure. Only explosionproof unions, located in accordance with 505.16(B)(1) through (B)(8). couplings, reducers, elbows, capped elbows, and conduit bodies similar to L, T, and cross types that are not larger (1) Type of Protection "d" or "e" Enclosures. Conduit than the trade size of the conduit shall be permitted be- seals shall be provided within 50 mm (2 in.) for each tween the sealing fitting and the explosionproof enclosure. conduit entering enclosures having type of protection (c) Where two or more explosionproof enclosures for "d" or •`e." which conduit seals are required under 505.16(B)(2) are Exception No. l: Where the enclosure having type of pro- connected by nipples or by runs of conduit not more than tec•tion ••d••is marked to indicate that a seal is not required. 900 mm (36 in.) long, a single conduit seal in each such nipple connection or run of conduit shall be considered Exception No. 2: For type of protection "e," conduit and sufficient if located not more than 450 mm (18 in.) from fittings entploying only NPT to NPT raceway joints or fit- either enclosure. tings listed for type of protection "e" shall be permitted between the enclosure and the seal, and the seal shall not (3) Pressurized Enclosures. Conduit seals shall be pro- be required to be within 50 inut (2 in.) of the entry. vided in each conduit entry into a pressurized enclosure where the conduit is not pressurized as part of the protec- FPN: Examples of fittings employing other than NPT tion system. Conduit seals shall be installed within 450 mm threads include conduit couplings, capped elbows, unions, (18 in.) from the pressurized enclosure. and breather drains. Exception No. 3: For conduit installed between type of• FPN No. 1: Installing the seal as close as possible to the protection ••e" enclosures employing only NPT to NPT enclosure reduces problems with purging the dead airspace in the pressurized conduit. raceway joints or conduit fittings listed for type of protec- tion "e," a seal shall not be required. FPN No. 2: For further information, see NFPA 496-2003, Standard for Purged and Pressurized Enclosures for Dec- (2) Explosionproof Equipment. Conduit seals shall be trical Equipment. provided for each conduit entering explosionproof equip- (4) Class I, Zone I Boundary.Conduit seals shall be pro- ment according to (13)(2)(a), (13)(2)(b), and (13)(2)(e). vided in each conduit run leaving a Class I, Zone 1 loca- (a) In each conduit entry into an explosionproof enclo- tion. The sealing fitting shall be permitted on either side of sure where either(1) the enclosure contains apparatus, such the boundary of such location within 3.05 m (10 ft) of the as switches, circuit breakers, fuses, relays, or resistors, that boundary and shall be designed and installed so as to mini- may produce arcs, sparks, or high temperatures that are mize the amount of gas or vapor within the Zone 1 portion considered to be an ignition source in normal operation, or of the conduit from being communicated to the conduit (2) the entry is metric designator 53 (trade size 2) or larger beyond the seal, Except for listed explosionproof reducers and the enclosure contains terminals, splices, or taps. For at the conduit seal, there shall be no union, coupling, box, the purposes of this section, high temperatures shall be or fitting between the conduit seal and the point at which considered to be any temperatures exceeding 80 percent of the conduit leaves the Zone I location. 2008 Edition NATIONAL ELECTRICAL CODE 70-,393 505.16 ARTICLE 505----CLASS I,ZONE 0, 1.AND 2 LOCATIONS Exception: Metal conduit containing no unions, couplings, being communicated to the conduit beyond the seal. Rigid boxes, or fittings and passing completely through a Class I, metal conduit or threaded steel intermediate metal conduit Zone I location with no fittings less than 300 mm (12 in.) shall be used between the sealing fitting and the point at beyond each boundary shall not require a conduit seal if which the conduit leaves the Zone 2 location, and a the termination points of the unbroken conduit are in un- threaded connection shall be used at the sealing fitting. classified locations. Except for listed explosionproof reducers at the conduit seal, there shall be no union, coupling, box, or fitting be- (5) Cables Capable of Transmitting Gases or Vapors. tween the conduit seal and the point at which the conduit Conduits containing cables with a gaslvaportight continu- leaves the Zone 2 location. ous sheath capable of transmitting gases or vapors through the cable core shall be sealed in the Zone I location after Exception No. 1: Metal conduit containing no unions, cou- removing the jacket and any other coverings so that the plings, boxes, or fittings and passing completely through a sealing compound surrounds each individual insulated con- Class I. Zone 2 location with no fittings less than 300 nun ductor and the outer jacket. (12 in.) beyond each boundary shall not be required to be Exception: Multiconductor cables with a gas/vaportighi sealed if the termination points of the unbroken conduit are continuous sheath capable of transmitting gases or vapors in unclassified locations. through the cable core shall he pennitted to be considered Exception No. 2: Conduit systems tenninating at an un- as a single conductor by sealing the cable in the conduit classified location where a wiring method transition is within 450 mm (IS in.) of the enclosure and the cable end made to cable tray, cablebus, ventilated busway, Type MI within the enclosure by an approved means to minimize the cable, or cable that is not installed in a raceway or cable entrance of gases or vapors and prevent the propagation of tray system shall not be required to be sealed where pass- flame into the cable core, or by other approved methods. ing from the Class I, Zone 2 location into the unclassified For shielded cables and twisted pair cables, it shall not be location. The unclassified location shall be outdoors or if required to remove the shielding material or separate the the conduit system is all in one room, it shall be permitted twisted pair to be indoors. The conduits shall riot terminate at an enclo- (6) Cables Incapable of Transmitting Gases or Vapors. sure containing an ignition source in normal operation. Each multiconductor cable in conduit shall be considered as Exception No. 3: Conduit systems passing from an enclo- a single conductor if the cable is incapable of transmitting sure or room that is unclassified as a result of pressuriza- gases or vapors through the cable core. These cables shall tion into a Class 1, Zone 2 location shall not require a seal be sealed in accordance with 505.16(D). at the boundary. (7) Cables Entering Enclosures.Cable seals shall be pro- FPN: For further information, refer to NFPA 496-2003, vided for each cable entering flameproof or explosionproof Standard for Purged and Pressurized Enclosures for Elec- enclosures. The seal shall comply with 505.16(D). trical Equipment. (8) Class I, Zone I Boundary. Cables shall be sealed at Exception No. 4: Segments of aboveground conduit systems the point at which they leave the Zone 1 location. shall not be required to be sealed where passing from a Class 1, Zane 2 location into an unclassified location if all Exception: Where cable is sealed at the termination point. the following conditions are Piet: (C) Zone 2. In Class 1, Zone 2 locations, seals shall be (1) No part of the conduit system segment passes located in accordance with 505.16(C)(1) and (C)(2). through a Class 1, Zone 0 or Class 1, Zone 1 location where the conduit contains unions, couplings, boxes, or fittings (1) Conduit Seals. Conduit seals shall be located in accor- within 300 mm (12 in.) of the Class 1, Zone 0 or Class 1, dance with (C)(1)(a) and (C)(1)(b). Zone 1 location. (a) For connections to enclosures that are required to (2) The conduit system segment is located entirely in be flameproof or explosionproof, a conduit seal shall be outdoor locations. provided in accordance with 505.16(B)(1) and (13)(2). All (3) The conduit system segment is not directly con- portions of the conduit run or nipple between the seal and nected to canned pumps,process or service connections for such enclosure shall comply with 505.16(B). flow, pressure, or analysis measurement, and so forth, that (b) In each conduit run passing from a Class I, Zone 2 depend on a single compression seal, diaphragm, or tube to location into an unclassified location. The sealing fitting prevent flammable or combustible fluids from entering the shall be permitted on either side of the boundary of such conduit system. location within 3.05 m (10 ft) of the boundary and shall be (4) The conduit system segment contains only threaded designed and installed so as to minimize the amount of gas metal conduit, unions, couplings, conduit bodies, and fit- or vapor within the Zone 2 portion of the conduit from tings in the unclassified location. 70-394 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 505—CLASS 1,'LONE 0, 1,AND 2 LOCATIONS 505.16 (5) The conduit systettt segment is sealed at its entry to Exception: Cables with an unbroken gas/vaportight con- each enclosure or fitting housing terminals, splices, or taps tinuous sheath shall be permitted to pass through u Class I, in Class 1, Zone 2 locations. Zane 2 location without seals. (2) Cable Seals. Cable seals shall be located in accordance (d) Cables Without Gas/Vaportight Continuous Sheath. with (C)(2)(a), (C)(2)(b), and (C)(2)(c). Cables that do not have gas/vaportight continuous sheath shall be sealed at the boundary of the Zone 2 and unclassi- (a) Explosionproof'and Flcttneproof Enclosures. Cables fied location in such a manner as to minimize the passage entering enclosures required to be flameproof or explosion- of gases or vapors into an unclassified location. proof shall be sealed at the point of entrance. The seal shall FPN: The cable sheath may be either metal or a nonmetal- comply with 505.16(D). Multiconductor cables with a lic material. gas/vaportight continuous sheath capable of transmitting gases or vapors through the cable core shall be sealed in the (D) Class I, Zones 0, 1, and 2. Where required, seals in Zone 2 location after removing the jacket and any other cov- Class 1, Zones 0, 1, and 2 locations shall comply with erings so that the sealing compound surrounds each individual 505.16(D)(1) through (D)(5). insulated conductor in such a manner as to minimize the pas- (1) Fittings. Enclosures for connections or equipment shall sage of gases and vapors. Multiconductor cables in conduit be provided with an integral means for sealing, or sealing shall be sealed as described in 505.16(B)(4). fittings listed for the location shall be used. Sealing fittings Exception No. 1: Cables passing from an enclosure or shall be listed for use with one or more specific compounds room that is unclassified as a result of Type Z pressuriza- and shall be accessible. tion into a Class 1, Zone 2 location shall not require it seal at the bnutldarti: (2) Compound.The compound shall provide a seal against passage of gas or vapors through the seal fitting, shall not Exception No. 2: Shielded cables and twisted pair cables be affected by the surrounding atmosphere or liquids, and shall not require the Ictnoval of the shielding material or sepa- shall not have a melting point less than 93°C (200 0F). ration of'the tts•isted pairs, provided the termination is by an approved means to minimize the entrance cf gases or vapors (3) Thickness of Compounds. In a completed seal, the and prevent propagation (fflcttne into the Cable core. minimum thickness of the sealing compound shall not be less than the trade size of the sealing fitting and, in no case, (b) Cables That Will Not Transmit Gases or Vapors. less than 16 mm 0/8 in.). Cables with a gas/vaportight continuous sheath and that will not transmit gases or vapors through the cable core in Exception: Listed cable sealing fittings shall not be re- excess of the quantity permitted for seal fittings shall not be quired to have a minitrucm thickness equal to the trade size required to be sealed except as required in 505.16(C)(2)(a). of the fitting. The minimum length of such cable run shall not be less (4) Splices and Taps. Splices and taps shall not be made in than the length that limits gas or vapor flow through;the fittings intended only for sealing with compound, nor shall cable core to the rate permitted for seal fittings [200 cm'/hr (0.007 ft3/hr) of air at a pressure of 1500 pascals (6 in. of other fittings in which splices or taps are made be filled water)]. with compound. {5) Conductor Fill. The cross-sectional area of the con- FPN No, 1; For further information on c4nstruetion, test- ductors permitted in a seal shall not exceed 25 percent of con- ing, and marking requirements for conduit sealing fittings, the cross-sectional area of a rigid metal conduit of the same see ANS1/UL 1203, Explosionproof and Dust-Ignition g Proof Electrical Equipment for Use in Hazardous(Classi- trade size unless it is specifically listed for a higher percent- fied)Locations. age of fill. FPN No.2: The cable core does not include the interstices (E) Drainage. of the conductor strands. (c) Cables Capable of Transmitting Gases or Vapors. (1) Control Equipment. Where there is a probability that Cables with a gaslvaporti liquid or other condensed vapor may be trapped within ght continuous sheath capable of enclosures for control equipment or at any point in the transmitting gases or vapors through the cable core shall raceway system, approved means shall be provided to pre- not be required to be sealed except as required in vent accumulation or to permit periodic draining of such 505.16(C)(2)(a), unless the cable is attached to process equip- liquid or condensed vapor. ment or devices that may cause a pressure in excess of 1500 pascals (6 in. of water) to be exerted at a cable end, in which (2) Motors and Generators. Where the authority having case a seal,barrier,or other means shall be provided to prevent jurisdiction judges that there is a probability that liquid or migration of flammables into an unclassified area. condensed vapor may accumulate within motors or genera- 2008 Edition NATIONAL F.I.E(rRICALCODE 70-395 505.17 ARTICLE 505—CLASS I,ZONE 0. 1,AND 2 LOCATIONS tors,joints and conduit systems shall be arranged to mini- (4) Be supported by clamps or by other suitable means in mize entrance of liquid. If means to prevent accumulation such a manner that there will be no tension on the or to permit periodic draining are judged necessary, such terminal connections means shall be provided at the time of manufacture and (5) Be provided with listed seals where the flexible cord shall be considered an integral part of the machine. enters boxes, fittings, or enclosures that are required to (3) Canned Pumps, Process, or Service Connections, be explosionproof or flameproof and So Forth. For canned pumps, process, or service con- Exception to (5): As provided in 505.16. nections for flow, pressure, or analysis measurement, and (6) Cord entering an increased safety "e" enclosure shall so forth, that depend on a single compression seal, dia- be terminated with a listed increased safety "e" cord phragm, or tube to prevent flammable or combustible fluids from entering the electrical conduit system, an additional connector. approved seal, barrier, or other means shall be provided to FPN: See 400.7 for permitted uses of flexible cords, prevent the flammable or combustible fluid from entering the conduit system beyond the additional devices or means Electric submersible pumps with means for removal if the primary seal fails. without entering the wet-pit shall be considered portable The additional approved seal or barrier and the inter- utilization equipment. The extension of the flexible cord connecting enclosure shall meet the temperature and pres- within a suitable raceway between the wet-pit and the sure conditions to which they will be subjected upon power source shall be permitted. failure of the primary seal, unless other approved means Electric mixers intended for travel into and out of open- are provided to accomplish the purpose in the preceding type mixing tanks or vats shall be considered portable uti- paragraph. lization equipment. Drains, vents, or other devices shall be provided so that FPN: See 505.18 for flexible cords exposed to liquids hav- primary seal leakage is obvious. ing a deleterious effect on the conductor insulation. FPN: See also the fine print notes to 505.16. 505.18 Conductors and Conductor Insulation. Process-connected equipment that is listed and marked "Dual Seal" shall not require additional process sealing (A) Conductors. For type of protection "e," field wiring when used within the manufacturer's ratings. conductors shall be copper. Every conductor (including spares) that enters Type "e" equipment shall be terminated FPN: For construction and testing requirements for dual seal process, connected equipment, refer to ANSI/ISA at a Type "e" terminal. 12.27.01-2003, Requirements for Process Sealing Between Electrical S'vstems and Potentiall_l Flammable or Cottbus- (B) Conductor Insulation. Where condensed vapors or tible Process Fluids. liquids may collect on, or come in contact with, the insula- tion on conductors, such insulation shall be of a type iden- 505.17 Flexible Cords, Class I,Zones 1 and 2.A flexible tified for use under such conditions, or the insulation shall cord shall be permitted for connection between portable be protected by a sheath of lead or by other approved lighting equipment or other portable utilization equipment means. and the fixed portion of their supply circuit. Flexible cord shall also be permitted for that portion of the circuit where 505.19 Uninsulated Exposed Parts.There shall be no un- the fixed wiring methods of 505.15(B) cannot provide the insulated exposed parts, such as electrical conductors, necessary degree of movement for fixed and mobile elec- buses, terminals, or components that operate at more than trical utilization equipment, in an industrial establishment 30 volts (15 volts in wet locations). These parts shall addi- where conditions of maintenance and engineering supervi- tionally be protected by type of protection ia, ib, or nA that sion ensure that only qualified persons install and service is suitable for the location. the installation, and the flexible cord is protected by loca- tion or by a suitable guard from damage. The length of the 505.20 Equipment Requirements. flexible cord shall be continuous. Where flexible cords are used, the cords shall comply with the following: (A) Zone 0. In Class 1, Zone 0 locations, only equipment (1) Be of a type listed for extra-hard usage specifically listed and marked as suitable for the location (2) Contain, in addition to the conductors of the circuit, an shall be permitted. equipment grounding conductor complying with Exception: Intrinsically safe apparatus listed for use in 400.23 Class I, Division I locations for the same gas, or as per- (3) Be connected to terminals or to supply conductors in an mitted by 505.9(B)(2), and with a suitable temperature approved manner class shall be permitted. 70-396 NATIONAL ELECTRICAL.CODE 2008 Edition ARTICLE 505—CLASS I,ZONE 0, 1.AND 2 LOCATIONS 505.25 (B) Zone 1. In Class I, Zone I locations, only equipment and generators of all voltage ratings shall be listed for specifically listed and marked as suitable for the location Class I, Zone 1 locations, and shall comply with all of shall be permitted. the following: Exception Nn. 1: Equipment identified for use in Class 1, (1) Motors shall be marked with the current ratio, I,IIN, Division I or listed f6r use in Class 1, Zone 0 locations fnr and time, tE. the same gas, or as permitted b*v 505.9(B)(2), and with a (2) Motors shall have controllers marked with the model or suitable temperature class shall be permitted. identification number, output rating (horsepower or Exception No. 2: Equipment identified for Class 1, Zane 1, kilowatt), full-load amperes, starting current ratio or Zone 2 type of protection "p" shall be pernitted, (1;11N), and time Up,.) of the motors that they are in- tended to protect; the controller marking shall also in- (C) Zone 2. In Class I, Zone 2 locations, only equipment elude the specific overload protection type (and setting, specifically listed and marked as suitable for the location if applicable) that is listed with the motor or generator. shall be permitted. (3) Connections shall be made with the specific terminals Exception Nu. 1: Equipment listed far use in Class 1, Zone listed with the motor or generator. 0 or Zone 1 locations for the scone gas, or as permitted b' (4) Terminal housings shall be permitted to be of substan- 505.9(B)(2), and with a suitable temperature class, shall be tial, nonmetallic, nonburning material, provided an in- pernutted, ternal grounding means between the motor frame and Exception No. 2: Equipment identified for Class 1, Zone I the equipment grounding connection is incorporated ,or Zane 2 type of protection ­p" shall be permitted. within the housing. Exception No. 3: Equipment identified for use in Class 1, (5) The provisions of Part III of Article 430 shall apply Division 1 or Division 2 locations.for the scene gas, or as regardless of the voltage rating of the motor, permitted by 505.9(B)(2), and with a suitable temperature (6) The motors shall be protected against overload by a class shall be permitted. separate overload device that is responsive to motor Exception No. 4: In Class 1, Zone 2 locations, the installa- current. This device shall be selected to trip or shall be tion of open or nonexplosionproof or nonflanteproof en- rated in accordance with the listing of the motor and its overload protection. closed ntntnrs, such as squirrel-cage induction motors without brushes, switching mechanisms, or similar arc- (7) Sections 430,32(C) and 430.44 shall not apply to such producing devices that are not identified for use in a Class motors. 1, Zone 2 location shall be permitted. (8) The motor overload protection shall not be shunted or FPN No. 1: It is important to consider the temperature of cut out during the starting period. internal and external surfaces that may be exposed to the flammable atmosphere. 505.25 Grounding and Bonding. Grounding and bonding FPN No. 2: It is important to consider the risk of ignition shall comply with Article 250 and the requirements in due to currents arcing across discontinuities and overheat- 505.25(A) and (B). ing or parts in multisection enclosures of large motors and generators. Such motors and generators may need equipo- (A) Bonding. The locknul-bushing and double-locknut tential bonding jumpers across joints in the enclosure and types of contacts shall not be depended on for bonding from enclosure to ground. Where the presence of ignitible purposes, but bonding jumpers with proper fittings or other gases or vapors is suspected, clean air purging may be approved means of bonding shall be used. Such means of needed immediately prior to and during start-up periods. bonding shall apply to all intervening raceways, fittings, (D) Manufacturer's Instructions. Electrical equipment boxes, enclosures, and so forth, between Class I locations installed in hazardous (classified) locations shall be in- and the point of grounding for service equipment or point stalled in accordance with the instructions (if any)provided of grounding of a separately derived system. by the manufacturer. Exception: The specific bonding means shall be required 505.21 Multiwire Branch Circuits. In a Class I, Zone I only to the nearest point where the grounded circuit con- location, a multiwire branch circuit shall not be permitted. ductor and the grounding electrode are connected together- on the line side of the building= or structure disconnecting Exception: Where the disconnect device(s)for the circuit means as specified in 250.32(B), provided the branch- opens all ungrounded conductors of the multiwire circuit circuit overcurrent protection is located on the load side of sintultaneousl. the disconnecting means. 505.22 Increased Safety "e" Motors and Generators. In FPN: See 250.100 for additional bonding requirements in Class I, Zone 1 locations, Increased Safety "e" motors hazardous (classified) locations. 2008 Edition NATIONAL.ELECTRICAL CODE 70-397 506.1 ARTICLE 506—ZONE 20,21,AND 22 LOCATIONS FOR COMBUSTIBLE DUSTS OR IGNITIBLE FIBERS/FL.YINUS (B) Types of Equipment Grounding Conductors. Fleas- dive themselves but that affect the energy in nonincendive ible metal conduit and liquidtight flexible metal conduit field wiring circuits and are relied upon to maintain nonin- shall not be used as the Sole ground-fault current path. cendive energy levels. Associated nonincendive field wir- Where equipment bonding jumpers are installed,they shall ing apparatus may be either of the following: comply with 250.102. (1) Electrical apparatus that has an alternative type of pro- Exception: In Class 1, Zane 2 locations, the bonding tection for use in the appropriate hazardous (classified) jumper shall be permitted to be deleted where all of the location fallowing conditions are met: (2) Electrical apparatus not so protected that shall not be (a) Listed liquidtight flexible metal conduit 1.8 m Oft) used in a hazardous (classified) location or less in length, with fittings listed for grounding, is used. FPN: Associated nonincendive field wiring apparatus has (b) Overcurrent protection in the circuit is limited to designated associated nonincendive field wiring apparatus 10 amperes or less. connections for nonincendive field wiring apparatus and (c) The load is not a power utilization load. may also have connections for other electrical apparatus. Dust-ignitionproof. Equipment enclosed in a manner that excludes dusts and does not permit arcs, sparks, or heat otherwise generated or liberated inside of the enclosure to cause ignition of exterior accumulations or atmospheric ARTICLE 506 suspensions of a specified dust on or in the vicinity of the Zone 20, 21, and 22 Locations enclosure. for Combustible Dusts FPN: For further information on dust-ignitionproof enclo- or Ignitible Fi i'bers/Flyings surer,see Type 9 enclosure in ANSI/NEMA 250-1991,En- closures for Electrical Equipment, and ANSIIUL 1203- 1994, Explo.sionproq f and Dust-Ignitionproof Electrical 506.1 Scope. This article covers the requirements for the Equipment for Hazardous(Classified) Locations. zone classification system as an alternative to the division Dusttight. Enclosures constructed so that dust will not en- classification system covered in Article 500, Article 502, ter under specified test conditions. and Article 503 for electrical and electronic equipment and wiring for all voltages in Zone 20, Zone 21, and Zone 22 Nonincendive Circuit. A circuit,other than field wiring, in hazardous (classified) locations where fire and explosion which any arc or thermal effect produced under intended hazards may exist due to combustible dusts or ignitible operating conditions of the equipment is not capable, under fiberslflyings. Combustible metallic dusts are not covered specified test conditions, of igniting the flammable gas–air, by the requirements of this article. vapor--air, or dust–air mixture. FPN No. 1: For the requirements for electrical and elec- FPN: Conditions are described in ANSUISA-12.12.01- tronic equipment and wiring for all voltages in Class 1, 2000,Nonincendive Electrical Equipment for Use in Class Division I or Division 2;Class II,Division I or Division 2; 1 and 11, Division 2, and Class 111, Divisions I and 2 Ha;- Class Ill, Division I or Division 2; and Class 1, Zone 0 or ardous(Classified)Locations. Zone I or Zone 2 hazardous (classified) locations where Nonincendive Equipment. Equipment having electrical/ fire or explosion hazards may exist due to flammable gases or vapors, flammable liquids, or combustible dusts or fi- electronic circuitry that is incapable, under normal operat- bers, refer to Articles 500 through 505. ing conditions, of causing ignition of a specified flammable FPN No. 2: Zone 20, Zone 21, and Zone 22 area classifi- gas–air,vapor–air,or dust--air mixture due to arcing or ther- cations are based on the modified IEC area classification mal means. system as defined in ANSMSA-61241-10(12.10.05)-2004, FPN: Conditions are described in ANSIASA-1112.01- Electrical Apparatus for Use in Zone 20, Zone 21, and 2000,Nonincendive Electrical Equipment for Use in Class Zane 22 Hazardous(Classified)Locations—Classification 1 and 11, Division 2, and Class 111, Divisions 1 and 2 Ha4 of Zane 20, Zone 21, and Zane 22 Hazardous (Classified) ardous(Classified)Locations. Locations(IEC61241-10 Mod). FPN No. 3• The unique hazards associated with explo- Nonincendive Field Wiring. Wiring that enters or leaves sives,pyrotechnics,and blasting agents are not addressed in an equipment enclosure and, under normal operating con- this article. ditions of the equipment, is not capable, due to arcing or thermal effects, of igniting the flammable gas–air, vapor-- 506.2 Definitions. For purposes of this article, the follow- air, or dust–air mixture. Normal operation includes open- ing definitions apply. ing, shorting, or grounding the field wiring. Associated Nonincendive Field Wiring Apparatus. Ap- Nonincendive Field Wiring Apparatus. Apparatus in- paratus in which the circuits are not necessarily nonincen- tended to be connected to nonincendive field wiring. 70--.39$ NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 506—ZONE 20,21,AND 22 LOCATIONS FOR COMBUSTIBLE DUSTS OR IGNITIBLE FIBERSIFLYINGS 506.5 FPN: Conditions are described in ANSI/ISA-12.12.01- Zone 20 Hazardous (Classified) Location. An area where 2000, Nonincendiv,Electrical Equipment for Use in Class combustible dust or ignitible fibers/flyings are present con- I and 11, Division _, and Class 111, Divisions I and 2 Haz- tinuously or for long periods of time in quantities sufficient ardous (Classified) Locations, q to be hazardous, as classified by 506.5(B)(1). Pressurized.The process of supplying an enclosure with a protective gas with or without continuous flow at sufficient Zone 21 Hazardous (Classified) Location. An area where pressure to prevent the entrance of combustible dust or combustible dust or ignitible fibers/flyings are likely to ex- ignitible fibers/flyings. ist occasionally under normal operation in quantities suffi- FPN: For further information, see ANSI/NFPA 496-2003, cient to be hazardous, as classified by 506.5(B)(2). Purged and Pressurized Enclosures for Electrical Zone 22 Hazardous (Classified) Location. An area where Equipment. combustible dust or ignitible fiberslflyings are not likely to Protection by Encapsulation "mD." Type of protection occur under normal operation in quantities sufficient to be where electrical parts that could cause ignition of a mixture hazardous, as classified by 506.5(B)(3). of combustible dust or fiberslflyings in air are protected by enclosing them in a compound in such a way that the ex- 506.4 General. plosive atmosphere cannot be ignited. (A) Documentation for Industrial Occupancies. Areas FPN No. 1: For additional information, see ISA-61241-19 designated as hazardous (classified) locations shall be prop- (I2.10.07)-2006,Electrical Apparatus for Use in Zone 20, erly documented. This documentation shall be available to Zone 21 and Zone 22 Hazardous(Classified)Locations— those authorized to design, install, inspect, maintain, or op- Protection by Encapsulation "mD". erate cectrical equipment. FPN No.2: Encapsulation is designated level of protection "maD" for use in Zone 20 locations. Encapsulation is des- (B) Reference Standards. Important information relat- ignated level of protection "mbD" for use in Zone 21 ing to topics covered in Chapter 5 are found in other locations. publications. Protection by Enclosure "tD2' Type of protection for ex- FPN: It is important that the authority having jurisdiction plosive dust atmospheres where electrical apparatus is pro- be Familiar with the recorded industrial experience as well vided with an enclosure providing dust ingress protection as with standards of the National Fire Protection Associa- and a means to limit surface temperatures. tion (NFPA), the ISA, International Society for Measure- ment and Control, and the International Electrotechnical FPN: For additional information, see ISA 61241-0 Commission (IEC) that may be of use in the classification (12.10.02),Electrical Apparatus for Use in Zone 20, Zone of various locations, the determination of adequate ventila- 21 and Zane 22 Hazardous(Classified)Locations—Gen- tion, and the protection against static electricity and light- eral Requirements (IEC 61241-0 Mod), and ISA 61241-1 ning hazards. (12.10.03), Electrical Apparatus for Use in Zone 21 and Zone 22 Hazardous(Classified)Locations—Protection by 506.5 Classification of Locations. Enclosure°'0"(IEC.'61241-1 Mod). Protection by Intrinsic Safety '4D2' 'hype of protection (A) Classifications of Locations. Locations shall be clas- where any spark or thermal effect is incapable of causing sified on the basis of the properties of the combustible dust ignition of a mixture of combustible dust,fibers, or flyings or ignitible fiberslflyings that may be present, and the like- in air under prescribed test conditions. lihood that a combustible or combustible concentration or quantity is present. Each room, section, or area shall be FPN: For additional information, see ISA 61241-11 considered individually in determining its classification. (12.10.06); Electrical Apparatusfor Use in Zone 20, Zane Where pyrophoric materials are the only materials used or 21 and Zone 22 Haza,rluns (Classified)Locations—Pro- handled,these locations are outside of the scope of this article. tection by Intrinsic Safety'ID." Protection by Pressurization "pD." Type of protection (B) Zone 20, Zone 21, and Zone 22 Locations. Zane 20, that guards against the ingress of a mixture of combustible Zone 21, and Zone 22 locations are those in which com- dust or fiberslflyings in air into an enclosure containing bustible dust or ignitible fiberslflyings are or may be electrical equipment by providing and maintaining a pro- present in the air or in layers, in quantities sufficient to tective gas atmosphere inside the enclosure at a pressure produce explosive or ignitible mixtures. Zone 20, Zone 21, above that of the external atmosphere. and Zone 22 locations shall include those specified in FPN: For additional information, see ISA 61241-2 506.5(B)(1), (B)(2), and (13)(3). (12.10.04). Electrical Apparatus far Use in Zone 21 and FPN: Through the exercise of ingenuity in the layout of Zane 22 Hazardous(Classified)Locations—Protection by electrical installations for hazardous (classified) locations, Pressurization 'pD." it is frequently possible to locate much of the equipment in 2008 Edition NATIONAL ELECTRICAL CODE 70-399 506.6 ARTICLE 506—ZONE 20,2l,AND 22 LOCATIONS FOR COMBUSTIBLE DUSTS OR IGNITIALE F.t$FRSIFLYINGS a reduced level of classification and, thus, to reduce the dust containment where explosive dust clouds are likely to amount of special equipment required. occur(but neither continuously,nor for long periods,nor f e- quendy) as, for example, silos (if Filled and/or emptied only (1) Zone 20. A Zone 20 location is a location in which occasionally)and the dirty side of filters if large self-cleaning (a) Ignitible concentrations of combustible dust or ig- intervals are occurring. nitible fibers/flyings are present continuously. (3) Zone 22. A Zone 22 location is a location (b) Ignitible concentrations of combustible dust or ig- nitible fibers/SyingS are present for long periods of time. {a} In which ignitible concentrations of combustible dust or ignitible fiberS/flyings are not likely to occur in FPN No. 1: As a guide to classification of Zone 20 loca- normal operation and, if they do occur, will only persist for tions, refer to AN-SMSA-61241-10 (12.10.05)-2004, Elec- a short period; or trical Apparatus for Use in Zone 20, Zone 21, and Zone 22 Hazardous(Classified)Locations— Classification of Zane (b) In which combustible dust or fiberslflyiAgS are handled, processed, or used but in which the dust or 20,Zone 21,and Zone 22 Hazardous(Classified)Locations (IEC61241-10 Mod). fiberslflyings are normally confined within closed containers FPN No. 2: Zone 20 classification includes locations inside of closed systems from which they can escape only as a result dust containment Systems;hoppers,silos,etc.,cyclones and of the abnormal operation of the equipment with which the filters,dust transport systems,except some parts of belt and dust or fibers/flyiagS are handled, processed, or used; or chain conveyors, etc.; blenders, mills, dryers, bagging (c) That is adjacent to a Zone 21 location, from which equipment, etc. ignitible concentrations of dust or fiberslflyings could be (2) Zone 21. A zone 21 location is a location communicated, unless such communication is prevented by adequate positive pressure ventilation from a source Of (a) In which ignitible concentrations of combustible clean air and effective safeguards against ventilation failure dust or ignitible fiberslflyings are likely to exist occasion- are provided. ally under normal operating conditions; or (b) In which ignitible concentrations of combustible FPN No. 1: As a guide to classification of Zone 22 loca- dust or ignitible fiberslflyings may exist frequently because of tions, refer to ANSLIISA-61241-10 (12.10.05)-2004, Elec- trical Apparatus for Use in Zane 20, Zane 21, and Zone 22 repair or maintenance operations or because of leakage; or Hazardous(Classified) Locations— Classification of Zone (c) In which equipment is operated or processes are car- 20,Zone 21,and Zone 22 Hazardous(Classified)Locations ried on, of such a nature that equipment breakdown or faulty (IEC61241-10 Mod). operations could result in the release of ignitible concentra- FPN No.2: Zone 22 locations usually include outlets from tions of combustible dust or ignitible fiberslflyings and also bag filter vents,because in the event of a malfunction there cause simultaneous failure of electrical equipment in a mode can be emission of combustible mixtures; locations near to cause the electrical equipment to become a source of igni- equipment that has to be opened at infrequent intervals or equipment that from experience can easily form leaks tion; or where, due to pressure above atmospheric, dust will blow (d) That is adjacent to a Zone 20 location from which out;pneumatic equipment,flexible connections that can be- ignitible concentrations of dust or ignitible fibers/flyings come damaged, etc.; storage locations for bags containing could be communicated, unless communication is pre- dusty product, since failure of bags can occur during han- vented by adequate positive pressure ventilation from a dling, causing dust leakage; and locations where control- source of clean air and effective safeguards against ventila- lable dust layers are formed that are likely to be raised into explosive dust-air mixtures. Only if the layer is removed Lion failure are provided, by cleaning before hazardous dust-air mixtures can be FPN No. 1: As a guide to classification of Zone 21 loca- formed is the area designated non-hazardous. tions, refer to ANSIIISA 61241-10 (12.10.05)-2004, Elec- FPN No. 3: Locations that normally are classified as Zone trical Apparatus for Use In Zone 20,Zone 21, and Zone 22 21 can fall into Zone 22 when measures are employed to Hazardous(Classified) Locations—Classification of Zane prevent the formation of explosive dust-air mixtures.Such 20,Zane 21,and Zone 22 Hazardous(Classified)Locations measures include exhaust ventilation.The measures should (IEC61241-10 Mod). be used in the vicinity of(bag) filling and emptying points, FPN No.2: This classification usually includes locations out- feed belts,sampling points,truck dump stations,belt dump side dust containment and in the immediate vicinity of access over points, etc. doors subject to frequent removal or opening for operation purposes when internal combustible mixtures are present; lo- 506.6 Special Precaution. Article 506 requires equipment cations outside dust containment in the proximity of filling construction and installation that ensures safe performance and emptying points,feed belts,sampling points,truck dump under conditions of proper use and maintenance. stations, belt dump over points, etc. where no measures are employed to prevent the formation of combustible mixtures; FPN: It is important that inspection authorities and users locations outside dust containment where dust accumulates exercise more than ordinary care with regard to the instal- and where due to process operations the dust layer is likely to lation and maintenance of electrical equipment in hazard- be disturbed and form combustible mixtures; locations inside ous (classified) locations. 70-400 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE.506—ZONE 2),21,AND 22 LOCATIONS FOR COMBUSTIBLE DUSTS OR IGNITIBLE FIBERS/FLYINGS 506.9 (A) Implementation of Zone Classification System. (G) Nonincendive Circuit.This protection technique shall Classification of areas, engineering and design, selection of be permitted for equipment in Zone 22 locations for which equipment and wiring methods, installation, and inspection it is identified, shall be performed by qualified persons. (H) Nonincendive Equipment. This protection technique (B) Dual Classification. In instances of areas within the shall be permitted for equipment in Zone 22 locations for same facility classified separately, Zone 22 locations shall which it is identified. be permitted to abut, but not overlap, Class II or Class III, Division 2 locations, Zone 20 or Zone 21 locations shall (I) Protection by Enclosure "tD". This protection tech- not abut Class II or Class III, Division 1 or Division 2 nique shall be permitted for equipment in Zone 21 and locations. Zone 22 locations for which it is identified. (C) Reclassification Permitted. A Class 1I or Class III, (J) protection by Pressurization "pD". This protection Division I or Division 2 location shall be permitted to be ue techni shall be u reclassified as a Zane 20, Zone 21, or Zone 22 location, q perm far equipment in Zone 2l and provided that all of the space that is classified because of a Zone 22 locations for which it is identified. single combustible dust or ignitible fiber/flying source is (K) Protection by Intrinsic Safety "W". This protection reclassified under the requirements of this article. technique shall be permitted for equipment in Zone 20, (D) Simultaneous Presence of Flammable Gases and Zone 21, and Zone 22 locations for which it is listed. Combustible Dusts or Fibers/Flyings. Where flammable gases, combustible dusts, or fiberslflyings are or may be 506.9 Equipment Requirements. present at the same time, the simultaneous presence shall be considered during the selection and installation of the elec- (A) Suitability. Suitability of identified equipment shall be trical equipment and the wiring methods, including the de- determined by one of the following: termination of the safe operating temperature of the electri- (1) Equipment listing or labeling cal equipment. (2) Evidence of equipment evaluation from a qualified test- ing laboratory or inspection agency concerned with 506.8 Protection Techniques. Acceptable protection tech- product evaluation niques for electrical and electronic equipment in hazardous (3) Evidence acceptable to the authority having jurisdiction (classified) locations shall be as described in 506.8(A) such as a manufacturer's self-evaluation or an owner's through (K). engineering judgment (A) Dust Ignitionproof.This protection technique shall be FPIV: Additional documentation for equipment may in- permitted for equipment in Zone 20, Zone 21, and Zone 22 elude certificates demonstrating compliance with applicable locations for which it is identified. equipment standards, indicating special conditions of uSe, (B) Pressurized. This protection technique shall be per- and other pertinent information, mitted for equipment in Zone 21 and Zone 22 locations for (B) Listing. which it is identified. (I) Equipment that is listed for Zone 20 shall be permitted (C) Intrinsic Safety. This protection technique shall be in a Zone 21 or Zone 22 location of the same dust or permitted for equipment in Zone 20, Zone 21, and Zone 22 ignitible fiber/flying, Equipment that is listed for Zone locations for which it is identified. Installation of intrinsi- 21 may be used in a Zone 22 location of the same dust cally safe apparatus and wiring shall be in accordance with fiber/flying. the requirements of Article 504. (2) Equipment shall be permitted to be listed for a specific (D) Dusttight. This protection technique shall be permit- dust or ignitible fiber/flying or any specific combina- tion of dusts fibers/11 ings. ted for equipment in Zone 22 locations for which it is identified. (C) Marking. (E) Encapsulation "maD". This protection technique (l) Division Equipment. Equipment identified for Class shall be permitted for equipment in Zone 20,Zone 21, and 11, Division I or Class Il, Division 2 shall, in addition to Zone 22 locations for which it is identified. being marked in accordance with 500.8(C), be permitted to (F) Encapsulation "rnbD". This protection technique be marked with both of the following: shall be permitted for equipment in Zone 21 and Zone 22 (1) Zone 20, 21, or 22 (as applicable) locations for which it is identified. (2) Temperature classification in accordance with 5069(D) 2008 Edition NATIONAL ELECTRICAL CODE 70-401 506.15 ARTICLE 506—ZONE 20,21,AND 22 LOCATIONS FOR COMBUSTIBLE DUSTS OR IGNMBI,.E FIHERSIFLYIIs1GS (2) Zone Equipment. Equipment meeting one or more of 506.20(B) and (C) shall be permitted to be marked in ac- the protection techniques described in 506.8 shall be cordance with 500.8(0) and Table 500.8(C). marked with the following in the order Shown: {1) Symbol "AEx" (E) Threading.All NPT threads referred to herein shall be threaded with a National (American) Standard Pipe Taper (2) Protection technique(s) in accordance with Table (NPT) thread that provides a taper of 1 in 16 ('la-in. taper 506.9(C)(2)(2) per foot). Conduit and fittings shall be made wrenchtight to (3) Zone prevent sparking when the fault current flows through the (4) Te m- perature classification, marked as a temperature conduit system and to ensure the integrity of the conduit value, in degrees C, preceded by T system. Equipment provided with threaded entries for field wiring connections shall be installed in accordance with (5} Ambient temperature marking in accordance with 506.9(E)(I) or (E)(2). 506.9(D) Table 506.9(C)(2)(2) Types of Protection Designation (1) Equipment Provided with Threaded Entries for NPT Threaded Conduit or Fittings. For equipment pro- vided with threaded entries for NPT threaded conduit or fit- tings, fisted conduit fittings, or cable fittings shall be used. iaD Protection by intrinsic safety 20 (2) Equipment Provided with Threaded Entries for ibD Protection by intrinsic safety 21 Metric Threaded Conduit or Fittings. For equipment with metric threaded entries, such entries shall be identified IiaDJ Associated apparatus Unclassified" as being metric, or listed adapters to permit connection to [ibD] Associated apparatus Unclassified** conduit or NPT-threaded fittings shall be provided with the equipment. Adapters shall be used for connection to con- maD Protection by encapsulation 20 duit or NPT-threaded fittings. Listed cable fittings that have mbD Protection by encapsulation 21 metric threads shall be permitted to be used. pD Protection by pressurization 21 (F) Fiber Optic Cable Assembly.Where a fiber optic cable assembly contains conductors that are capable of carrying cur tD Protection by enclosures 21 rent,the fiber optic cable assembly shall be installed in aceor- dancce with 506.15 and 506.16, as applicable, *Does not address use where a combination of techniques is used. **Associated apparatus is permitted to be installed in a hazardous(clan- 506.15 Wiring Methods. Wiring methods shall maintain sited)location if suitably protected using another type of protection. the integrity of the protection techniques and shall comply (D) Temperature Classifications. Equipment shall be with 506.15(A), (B), or (C). marked to show the operating temperature referenced to a 40°C (104'F) ambient. Electrical equipment designed for (A) Zone 20. In Zone 20 locations, the wiring methods in use in the ambient temperature range between —20°C and (1) through (5) shall be permitted. +40°C shall require no additional ambient temperature (1) Threaded rigid metal conduit or threaded steel interme- marking. Electrical equipment that is designed for use in a diate metal conduit. range of ambient temperatures other than—20°C and+40°C (2) Type MI cable with termination fittings listed for the is considered to be special;and the ambient temperature range location. Type MI cable shall be installed and sup- shall then he marked on the equipment, including either the ported in a manner to avoid tensile stress at the termi- symbol 'Ta" or "lamb" together with the special range of nation fittings, ambient temperatures. As an example, such a marking might Exception: MI cable and fittings fisted for Class II, Divi- be "-30°C <— Ta < +40°C." Electrical equipment suitable for sion 1 locations are permitted to be used. ambient temperatures exceeding 40°C (104°F) shall be (3) In industrial establishments with limited public access, marked with both the maximum ambient temperature and the where the conditions of maintenance and supervision operating temperature at that ambient temperature. ensure that only qualified persons service the installation, Exception No. 1: Equipment of the non—heat-producing Type MC-HL cable, listed for use in Zone 20 locations, type, such as conduit fittings, shall not be required to have with a gastvaportight continuous corrugated metallic a marked operating temperature. sheath and overall jacket of suitable polymeric material,a separate equipment grounding conductors)in accordance Exception No. 2: Equipment identified for Class Il, Divi- with 250.122,and provided with termination fittings listed sion I or Class 11, Division 2 locations as permitted by for the application, shall be permitted. 70-402 NATIONAL ELECTRICAL.CODE 2008 Edition ARTICLE 506—ZONE 20. 21,AND 22 LOCATIONS FOR COMBUSTIBLE DUSTS OR IGNITIBLE FIBERS/FLYINGS 506.20 Exception: Type MC-HL cable and fittings listed for Class cuit, provided the simple apparatus does not intercon- 11, Division I locations are permitted to be used. nect the nonincendive field wiring circuit to any other FPN: See 330.12 for restrictions on use of Type MC cable. circuit. (4) Fittings and boxes shall be identified for use in Zone 20 FPN: Simple apparatus is defined in 504.2. locations. Separation of nonincendive field wiring circuits shall Exception: Boxes and fittings listed for Class 11, Division 1 be in accordance with one of the following: locations are permitted to be used. a. Be in separate cables (5) Where necessary to employ flexible connections, liq- b. Be in multiconductor cables where the conductors uidtight flexible metal conduit with listed fittings, liq- of each circuit are within a grounded metal shield uidtight flexible nonmetallic conduit with listed fittings, c. Be in multiconductor cables where the conductors or flexible cord listed for extra-hard usage and provided have insulation with a minimum thickness of with listed fittings shall be used. Where flexible cords 0.25 mm (0.01 in.) are used, they shall also comply with 506.17. Where (8) Boxes and fittings shall be dusttight. flexible connections are subject to oil or other corrosive conditions, the insulation of the conductors shall be of 506,16 Sealing. Where necessary to protect the ingress of a type listed for the condition or shall be protected by combustible dust or ignitible fibers/flyings, or to maintain means of a suitable sheath. the type of protection, seals shall be provided. The seal Exception: Flexible conduit and flexible conduit and cord shall be identified as capable of preventing the ingress of fittings listed for Class A Division I locations are permit- combustible dust or ignitible fibers/flyings and maintaining ted to be used. the type of protection but need not be explosionproof or FPN: See 506.25 for grounding requirements where flex- flameproof. ible conduit is used. 506.17 Flexible Cords. Flexible cords used in Zone 20, (B) Zone Zl. In Zone 21 locations, the wiring methods in Zone 21,and Zone 22 locations shall comply with all of the (13)(1) and {B)(2) shall be permitted. following: (1) All wiring methods permitted in 506.15(A). (1) Be of a type listed for extra-hard usage (2) Fittings and boxes that are dusttight, provided with (2) Contain, in addition to the conductors of the circuit, an threaded bosses for connection to conduit, in which equipment grounding conductor to com ] with taps,joints, or terminal connections are not made, and complying g 400.23 are not used in locations where metal dust is present, may be used. (3) Be connected to terminals or to supply conductors in an approved manner (C) Zone 22, In Zone 22 locations, the wiring methods in (4) Be supported by clamps or by other suitable means in (1) through (8) shall be permitted. such a manner to minimize tension on the terminal (1) All wiring methods permitted in 506.15(B), connections (2) Rigid metal conduit, intermediate metal conduit, elec- (5) Be provided with suitable seals to prevent the entrance trical metallic tubing, dusttight wireways. of combustible dust or ignitible fibers/flyings where the (3) Type MC or MI cable with listed termination fittings. flexible cord enters boxes or fittings (4) Type PLTC in cable trays. 506.20 Equipment installation. (5) Type ITC in cable trays. (6) Type MC, M1, MV, or TC cable installed in ladder, (A) Zone 20. In Zone 20 locations, only equipment listed ventilated trough, or ventilated channel cable trays in a and marked as suitable for the location shall be permitted. single layer, with a space not less than the larger cable diameter between two adjacent cables, shall be the wir- Exception: Intrinsically safe apparatus listed fir use in ing method employed. Single-conductor Type MV Class 11, Division 1 locations with a suitable temperature cables shall be shielded or metallic armored. class shall be permitted. (7) Nonincendive field wiring shall be permitted using any (B) Zone 21. In Zone 21 locations, only equipment listed of the wiring methods permitted for unclassified loca- and marked as suitable for the location shall be permitted. tions. Nonincendive field wiring systems shall be in- stalled in accordance with the control drawing(s). Exception No. 1: Apparatus listed for Ilse in Class 11, Di- Simple apparatus, not shown on the control drawing, vision 1 locations tivith a suitable temperature class shall be shall be permitted in a nonincendive field wiring cir- permitted. 2008 Edition NATIONAL ELECTRICAL CODE 70-403 506.21 ARTICLE 511—COMMERCIAL GARAGES,REPAIR AND STORAGE Exception No. 2: Pressurized equipment identified for disconnecting means as specified in 250.32(B) if the branch Class II, Division I shall be permitted side overcurrent protection is located on the load side of (C) Zone 22. In Zone 22 locations, only equipment listed the disconnecting means. and marked as suitable For the location shall be permitted. FPN: See 250.100 for additional bonding requirements in Exception No. 1: Apparatus listed for use in Class II, Di- hazardous (classified) locations. vision 1 or Class II, Division 2 locations with a suitable (B) Types of Equipment Grounding Conductors. Liq- temperature class shall be permitted. uidtight flexible metal conduit shalt not be used as the sole Exception No. 2: Pressurized equipment identified for ground-fault current path.Where equipment bonding jump- Class II, Division 1 or Division 2 shall be permitted. ers are installed, they shall comply with 250.102. (D) Manufacturer's Instructions. Electrical equipment Exception: In Zane 22 locations, the bonding jumper shall installed in hazardous (classified) locations shall be in- be permitted to be deleted where all of the following con- stalled in accordance with the instructions (if any) provided ditions are met: by the manufacturer. (1) Listed liquidtight flexible metal conduit 1.8 tit (6 ft) or (E) Temperature. The temperature marking specified in less in length, with fittings listed far grounding, is used. 506.9(C)(2)(5) shall comply with (E)(1) or (E)(2): (2) Overcurrent protection in the circuit is limited to 10 am- (1) For combustible dusts, less than the lower of either the Peres or less. layer or cloud ignition temperature of the specific com- (3) The load is not a power utilization load bustible dust. For organic dusts that may dehydrate or carbonize, the temperature marking shall not exceed the lower of either the ignition temperature or 165°C(329°F). (2) For ignitible fiberslflyings, less than 165°C (329°F) for ARTICLE 510 equipment that is not subject to overloading, or 120°C Hazardous (Classified) Locations — (248°F) for equipment (such as motors or power trans- formers) that may be overloaded. Specific FPN: See NFPA 499-2004,Recommended Practice for the Classification of Combustible Dusts and of Hazardous 510.1 Scope. Articles 511 through 517 cover occupancies (Classified)Locations for Electrical Installations in Chemi- or parts of occupancies that are or may be hazardous be- cal Processing Areas, for minimum ignition temperatures cause of atmospheric concentrations of flammable liquids, of specific dusts. gases,or vapors,or because of deposits or accumulations of 506.21 Multiwire Branch Circuits. In Zone 20 and Zone materials that may be readily ignitible. 21 locations, a multiwire branch circuit shall not be permitted. 510.2 General. The general rules of this Code and the Exception: Where the disconnect device(s)for the circuit provisions of Articles 500 through 504 shall apply to elec- opens all ungrounded conductors of the nultiwire circuit trical wiring and equipment in occupancies within the simultaneously. scope of Articles 511 through 517, except as such rules are modified in Articles 511 through 517. Where unusual con- 506.25 Grounding and Bonding. Grounding and bonding ditions exist in a specific occupancy, the authority having shall comply with Article 250 and the requirements in jurisdiction shall judge with respect to the application of 506.25(A) and (B). specific rules. (A) Bonding.The locknut-bushing and double-locknut types of contacts shall not be depended on for bonding purposes,but bonding jumpers with proper fittings or other approved means of bonding shall be used. Such means of bonding shall apply ARTICLE 511 to all intervening raceways, fittings,boxes,enclosures, and so Commercial Garages, Repair forth, between Zone 20, Zone 21, and Zone 22 locations and and Storage the point of grounding for service equipment or point of grounding of a separately derived system. Exception: The .specific bonding means shall be required FPN: Rules that are followed by a reference in brackets contain text that has been extracted from NFPA 30A-2006, only to the nearest point where the grounded circuit con- Code for Motor Fuel Dispensing Facilities and Repair Ga- ductor and the grounding electrode conductor are con- rages. Only editorial changes were made to the extracted nected together on the line side of the building or structure text to make it consistent with this Code. 7(-404 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 511 —COMMERCIAL.GARAGES, REPAIR AND STORAGE 511.3 511.1 Scope. These occupancies shall include locations will not be dispensed, but repair activities that involve the used for service and repair operations in connection with transfer of such fluids or gases are performed, the classifi- self-propelled vehicles (including, but not limited to, pas- cation rules in (1), (2), and (3) shall apply. senger automobiles, buses, trucks, and tractors) in which volatile flammable liquids or flammable gases are used for (1) Floor Areas. fuel or power. (a) Ventilation Provided.The floor area shal'I be unclas- sified where there is mechanical ventilation providing a 511.2 Definitions. minimum of four air changes per hour or one cubic foot per Major Repair Garage. A building or portions of a build- minute of exchanged air for each square foot of floor area. ing where major repairs, such as engine overhauls, paint- Ventilation shall provide for air exchange across the entire ing,body and fender work,and repairs that require draining floor area, and exhaust air shall be taken at a point within of the motor vehicle fuel tank are performed on motor 0.3 m (12 in.) of the floor. vehicles, including associated floor space used for offices, (b) Ventilation Not Provided.The entire Moor area up to parking, or showrooms. [30A:3.3.12.11 a level of 450 mm (18 in.) above the floor shall be classi- fied as Class 1,Division 2 if the ventilation does not comply Minor Repair Garage. A building or portions of a build- with 511.3(C)(1)(a). ing used for lubrication, inspection, and minor automotive maintenance work,such as engine tune-ups,replacement of (2) Ceiling Areas. Where lighter-than-air gaseous fueled parts, fluid changes (e.g., oil, antifreeze, transmission fluid, vehicles, such as vehicles fueled by natural gas or hydro- brake fluid, air-conditioning refrigerants), brake system re- gen, are repaired or stored, the area within 450 mm(18 in.) pairs, tire rotation, and similar routine maintenance work, of the ceiling shall be considered for classification in accor- including associated floor space used for offices,parking,or dance with (a) and(b). showrooms. [30A:3.3.12.2] (a) Ventilation Provided. The ceiling area shall be un- 511.3 Area Classification, General.Where Class I liquids classified where ventilation is provided, from a point not or gaseous fuels are stored,handled, or transferred, electri- less than 450 mm (18 in.) from the highest point in the cal wiring and electrical utilization equipment shall be de- ceiling, to exhaust the ceiling area at a rate of not less than signed in accordance with the requirements for Class I, Q•3 m3/mtnlrn2 (1 cfm/ft`) of cei+ling area at all times that Division 1 or 2 hazardous (classified) locations as classified the building is occupied or when vehicles using lighter- in accordance with 500.5 and 500.6, and this article. A than-air gaseous fuels are parked below this area. Class I location shall not extend beyond an unpierced wall, (b) Ventilation Not Provided. Ceiling areas that are not roof, or other solid partition that has no openings. ventilated in accordance with 511.3(C)(2)(a) shall be clas- [30A:8.3.5, 8.3.21 sified as Class 1, Division. 2. (A) Parking Garages.Parking garages used for parking or (3) Pit Areas in Lubrication or Service Room. Any pit, storage shall be permitted to be unclassified. belowgrade work area, or subfloor work area shall be clas- sified as provided in (a) or (b). FPN: For further information, see NFPA 88A-2007, Stan- dard for Parking Structures,and NFPA 30A-2008,Code for (a) Ventilation Provided.The pit area shall be a Class I, Motor Fuel Dispensing Facilities and Repair Garages. Division 2 location where there is mechanical ventilation providing a minimurn of six air changes per hour. (B) Repair Garages, With Dispensing. Major and minor (b) Ventilation Not Provided. Where ventilation is not repair garages that dispense motor fuels into the fuel tanks provided in accordance with 511.3(C)(3)(a), any pit or de- of vehicles, including flammable liquids having a flash pression below floor level shall be a Class I, Division 1 point below 38°C (100°F) such as gasoline, or gaseous location that extends up to the floor level. fuels such as natural gas, hydrogen, or LPG,shall have the dispensing functions and components classified in accor- (D) Minor Repair Garages. Where flammable liquids dance with Table 514.3(5)(1) in addition to any classifica- having a flash point below 38°C (100°F) such as gasoline, tion required by this section. Where Class I liquids, other or gaseous fuels such as natural gas or hydrogen, will not than fuels, are dispensed, the area within 900 mm(3 ft) of be dispensed or transferred, the classification rules in any fill or dispensing point, extending in all directions, (D)(1), (D)(2),and(D)(3)shall apply to the Iubrication and shall be a Class I, Division 2 location. service rooms. (C) Major Repair Garages. Where flammable liquids (1) Floor Areas.Floor areas in minor repair garages without having a flash point below 38°C (100M such as gasoline, pits, belowgMde work areas, or subfloor work areas shall be or gaseous fuels such as natural gas, hydrogen, or LPG, unclassified.Where floor areas include pits,belowgrade work 2008 Edition NATIONAL ELECTRICAL CODE 70-405 511.4 ARTICLE 511—COMMERCIAL GARAGES.REPAIR AND ST012AGE areas,or subfloor work areas in Iubrication or service rooms, (B) Equipment Located in Class I Locations. Within the classification rules in(a)or(b) shall apply. Class I locations as defined in 511.3, equipment shall con- (a) Ventilation Provided. The entire floor area shall be form to applicable provisions of Article 501. unclassified where there is mechanical,ventilation provid- (1) Fuel-Dispensing Units. Where fuel-dispensing units ing a minimum of four air changes per hour or one cubic (other than liquid petroleum gas, which is prohibited) are foot per minute of exchanged air for each square foot of located within buildings, the requirements of Article 514 floor area.Ventilation shall provide for air exchange across shall govern. the entire floor area, and exhaust air shall be taken at a Where mechanical ventilation is provided in the dis- point within 0.3 m (12 in.) of the floor. pensing area, the control shall be interlocked so that the (b) Ventilation Not Provided The floor area up to a dispenser cannot operate without ventilation, as prescribed level of 450 mm(1$in.)above any unventilated pit,below- in 500.5(B)(2). grade work area, or subfloor work area and extending a distance of 900 mm(3 ft)horizontally from the edge of any (2) Portable Lighting Equipment. Portable lighting such pit,belowgrade work area,or subfloor work area,shall equipment shall be equipped with handle, lampholder, be classified as Class I, Division 2. hook, and substantial guard attached to the lampholder or handle. All exterior surfaces that might come in contact (2) Ceiling Areas. Where ligbter-than-air gaseous fuels with battery terminals, wiring terminals, or other objects (such as natural gas or hydrogen) will not be transferred, shall be of nonconducting material or shall be effectively such locations shall be unclassified. protected with insulation. Lampholders shall be of an un- (3) Pit Areas in Lubrication or Service Room. Any pit, switched type and shall not provide means for plug-in of belowgrade work area, or subtioor work area shall be clas- attachment plugs. The outer shell shall be of molded com- sified as provided in (a) or (b). position or other suitable material. Unless the lamp and its cord are supported or arranged in such a manner that they (a} Ventilation Provided Where ventilation is provided cannot be used in the locations classified in 511.3, they shall to exhaust the pit area at a rate of not less than 0.3 be of a type identified for Class I, Division 1 locations. m 3/rnin/m� (l cfm/fe) of floor area at all times that the building is occupied,or when vehicles ace parked in or over 511,7 Wiring and Equipment Installed Above Class I this area and where exhaust air is taken from a point within Locations. 300 mm (12 in.) of the floor of the pit, belowgrade work area, or subfloor work area, the pit shall be unclassified. (A) Wiring in Spaces Above Class I Locations. [30A:7.4.5.4. Table 8.3.11 (1) Fixed Wiring Above Class I Locations. All fixed wir- (b) Ventilation Not Provided. Where ventilation is not ing above Class I locations shall be in metal raceways,rigid provided in accordance with 5113(D)(3)(a), any pit or de- nonmetallic conduit, electrical nonmetallic tubing, flexible pression below floor level shall be a Class 1, Division 2 metal conduit, liquidtight flexible metal conduit, or liq- location that extends up to the floor level. uidtight flexible nonmetallic conduit, or shall be Type MC, (E) Modifications to Classification. AC, MI, manufactured wiring systems, or PLTC cable in accordance with Article 725,or Type TC cable or Type ITC (x) Specific Arens Adjacent to Classified Locations. Ar- cable in accordance with Article 727. Cellular metal floor eaS adjacent to classified Iocations in which flammable va- raceways or cellular concrete floor raceways shall be per- pors are not Iikely to be released, such as stock rooms, mitted to be used only for supplying ceiling outlets or ex- switchboard rooms, and other similar locations, shall be tensions to the area below the floor,but such raceways shall unclassified where mechanically ventilated at a rate of four have no connections leading into or through any Class I or more air changes per hour, or designed with positive air location above the floor, pressure, or where effectively cut off by walls or partitions. (2) Alcohol-Based Windshield Washer Fluid. The area (2) Pendant. For pendants, flexible cord suitable for the used for Storage, handling, or dispensing into motor ve- type of service and listed for hard usage shall be used. hicles of alcohol-based windshield washer fluid in repair (B) Electrical Equipment Installed Above Class I garages shall be unclassified unless otherwise classified by Locations. a provision of 5I1.3. [30.4:83.5,Exception) • (1) Fixed Electrical Equipment.Electrical equipment in a 511.4 Wiring and Equipment in Class I Locations. fixed position shall be located above the level of any de- (A) Wiring Located in Class I Locations. Within Class I fined Class I location or shall be identified for the location. locations as classified in 511.3, wiring shall conform to (a) Arcing Equipment.Equipment that is less than 3.7 m applicable provisions of Article 501. (12 ft) above the floor level and that may produce arcs, 70-406 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 513—AIRCRAFT HANGARS 513.2 sparks, or particles of hot metal, such as cutouts, switches, (B) Supplying Circuits with Grounded and Grounding charging panels, generators, motors, or other equipment Conductors in Class I Locations. Grounding in Class I (excluding receptacles, lamps, and lampholders) having locations shall comply with 501,30. make-and-break or sliding contacts, shall be of the totally Pen- enclosed type or constructed so as to prevent the escape of (1} Circuits Supplying Portable Equipment or Pen- sparks or hot metal particles. dants. Where a circuit supplies portables or pendants and (b) Fitot Lighting.pa Lamps and [ampholders for fixed includes a grounded conductor as provided in Article 200, lighting that is located over lanes through which vehicles receptacles, attachment plugs, connectors, and similar de- are commonly driven or that may otherwise be exposed to vices shall be of the grounding type, and the grounded physical damage shall be located not less than 3.7 m (12 ft) conductor of the flexible cord shall be connected to the above flour level, unless of the tata[ly enclosed type or screw shell of any lampholder or to the grounded terminal constructed so as to prevent escape of sparks or hot metal of any utilization equipment supplied. particles. (2) Approved Means. Approved means shall be provided for maintaining continuity of the equipment grounding con- 511.9 Sealing. Seals complying with the requirements of ductor between the fixed wiring system and the non-- 501.15 and 501.15(B)(2) shall be provided and shall apply current-carrying metal portions of pendant luminaires, Por- to horizontal as well as vertical boundaries of the defined table luminaires, and portable utilization equipment. Class I locations. 511.10 Special Equipment. (A) Battery Charging Equipment. Battery chargers and ARTICLE 513 their control equipment, and batteries being charged, shall Aircraft Hangars not be located within locations classified in 511.3. (B) Electric Vehicle Charging Equipment. 513.1 Scope.This article shall apply to buildings or struc- tures in any part of which aircraft containing Class I (flam- {1) General. All electrical equipment and wiring shall be mable) liquids or Class II (combustible) liquids whose tem- installed in accordance with Article 6_5, except as noted in peratures are above their flash points are housed or stored 511.10{B}12) and IB}{3). Flexible cords shall be of a type and in which aircraft might undergo service, repairs, or identified for extra-hard usage. alterations. It shall not apply to locations used exclusively (2) Connector Location. No connector shall be located for aircraft that have never contained fuel or unfueled air- within a Class I location as defined in 511.3. craft, (3) Plug Connections to Vehicles. Where the cord is sus- FPN No. 1: For definitions of aircraft hangar and unfueled pended from overhead, it shall be arranged so that the low- aircraft, see NFPA 409-2004, Standard nn Aircraft Hangars. est point of sag is at least 150 mm (6 in.) above the floor. Where an automatic arrangement is provided to pull both FPN No. 2: For further information on fuel classification see NFPA 30-2008, Flammable and Combustible Liquids cord and plug beyond the range of physical damage, no Code. additional connector shall be required in the cable or at the outlet. 513.2 Definitions. For the purpose of this article, the fol- Iowing definitions shall apply. 51I.12 Ground-Fault Circuit-Interrupter Protection for Personnel. All 125-volt, single-phase, 15- and 20-ampere Aircraft Painting Hangar. An aircraft hangar constructed receptacles installed in areas where electrical diagnostic for the express purpose of spray/coating/dipping appliea- equipment,electrical hand tools, or portable lighting equip- tions and provided with dedicated ventilation supply and ment are to be used shall have ground-fault circuit- exhaust. interrupter protection for personnel. Mobile Equipment.Equipment with electrical components suitable to be moved only with mechanical aids or is pro- 511.16 Grounding and Bonding Requirements. vided with wheels for movement by person(s) or powered (A) General Grounding Requirements. All metal race- devices. ways, the metal armor or metallic sheath on cables, and all Portable Equipment. Equipment with electrical compo- non—current-carrying metal parts of fixed or portable elec- nents suitable to be moved by a single person without me- trical equipment, regardless of voltage, shall be grounded. chanical aids. 2008 Edition NATIONAL ELECTRICAL CODE 70-407 513.3 ARTICLE 513 AIRCRAFT HANGARS 513.3 Classification of Locations. comply with the applicable provisions of Article 501 or Article (A) Below Floor Level. Any pit or depression below the 505 for the division or zone in which they are used. level of the hangar floor shall be classified as a Class I, 513.7 Wiring and Equipment Not Installed in Class I Division I or Zone I location that shall extend up to said Locations. floor level. (A) Fixed Wiring. All fixed wiring in a hangar but not (B) Areas Not Cut Off or Ventilated. The entire area of installed in a Class I location as classified in 513.3 shall be the hangar, including any adjacent and communicating ar- installed in metal raceways or shall be Type Ml,TC,or MC eas not suitably cut off from the hangar, shall be classified cable. as a Class I, Division 2 or Zone 2 location up to a level 450 mm {18 in.) above the floor. Exception: Wiring in unclassified locations, as described in 513.3(D), shall be permitted to be any suitable type (C) Vicinity of Aircraft. wiring method recognized in Chapter 3. (1) Aircraft Maintenance and Storage Hangars. The (B) Pendants. For pendants, flexible cord suitable for the area within 1.5 m (5 ft) horizontally from aircraft power type of service and identified for hard usage or extra-hard plants or aircraft fuel tanks shall be classified as a Class 1, usage shall be used. Each such cord shall include a separate Division 2 or Zone 2 location that shall extend upward equipment grounding conductor. from the floor to a level 1.5 m (5 ft) above the upper surface of wings and of engine enclosures, (C) Arcing Equipment. In locations above those de- scribed in 513.3, equipment that is less than 3.0 m (10 ft) (2) Aircraft Painting Hangars. The area within 3 m above wings and engine enclosures of aircraft and that may (10 ft)horizontally from aircraft Surfaces from the floor to produce arcs, sparks, or particles of hot metal, such as 3 in(10 ft) above the aircraft shall be classified as Class I, lamps and lampholders for fixed lighting, cutouts, switches, Division 1 or C1aSS I, Zone 1. The area horizontally from receptacles, charging panels, generators, motors, or other aircraft surfaces between 3.0 m (10 ft) and 9.0 m (30 ft) equipment having make-and-break or sliding contacts, shall from the floor to 9.0 m (30 ft) above the aircraft surface be of the totally enclosed type or constructed so as to pre- shall be classified as Class 1,Division 2 or Class 1,Zone 2. vent the escape of sparks or hot metal particles. FPN: See NFPA 33-2007, Standard for Spray Application Exception: Equipment in areas described in 513.3(D)shall Using Flammable or Combustible Materials, for informa- be permitted to be of the general-purpose type. tion on ventilation and grounding for static protection in spray painting areas. (D) Lampholders. Lampholders of metal-shell, fiber-lined (D) Areas Suitably Cut Off and Ventilated. Adjacent ar- types shall not be used for fixed incandescent lighting. eas in which flammable liquids or vapors are not likely to (E) Stanchions, Rostrums, or Docks. Where stanchions, be released, such as stock rooms, electrical control rooms, rostrums, or docks are not located or likely to be located in and other similar locations, shall be unclassified where ad- a Class I location,as defined in 513.3(C),wiring and equip- equately ventilated and where effectively cut off from the ment shall comply with 513.7, except that such wiring and hangar itself by walls or partitions. equipment not more than 457 mm (18 in.) above the floor in any position shall comply with 513.4(B). Receptacles 513.4 Wiring and Equipment in Class I Locations. and attachment plugs shall be of a locking type that will not (A) General. All wiring and equipment that is or may be readily disconnect. installed or operated within any of the Class I locations (F) Mobile Stanchions. Mobile stanchions with electrical defined in 513.3 shall comply with the applicable provi- equipment complying with 513.7(E) shall carry at least one sions of Article 501 or Article 505 for the division or zone permanently affixed warning sign with the following words in which they are used. or equivalent: Attachment plugs and receptacles in Class I locations shall be identified for Class I locations or shall be designed WARNING such that they cannot be energized while the connections KEEP 5 FT CLEAR OF AIRCRAFT ENGINES are being made or broken. AND FUEL TANK AREAS (B) Stanchions, Rostrums, and Docks. Electrical wiring, or outlets, and equipment (including lamps) on or attached to WARNING stanchions, rostrums, or docks that are located or likely to be KEEP 1.5 METERS CLEAR OF AIRCRAFT ENGINES located in a Class I location, as defined in 513.3(C), shall AND FUEL TANK AREAS 70-408 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 513—AIRCRAFT HANGARS 513.10 513.8 Underground Wiring. (18 in.) above floor level and shall not be operated in a (A) Wiring and Equipment Embedded, Under Slab, or Class I location as defined in 513.3(C). Underground. All wiring installed in or under the hangar (2) Marling for Mobile Units. Mobile energizers shall floor shall comply with the requirements for Class I, Divi- carry at least one permanently affixed warning sign with the sion 1 locations. Where such wiring is located in vaults, following words or equivalent: pits, or ducts, adequate drainage shall be provided. WARNING (B) Uninterrupted Raceways, Embedded, Under Slab, KEEP 5 FT CLEAR OF AIRCRAFT ENGINES or Underground. Uninterrupted raceways that are embed- AND FUEL TANK AREAS ded in a hangar floor or buried beneath the hangar floor or shall be considered to be within the Class I location above the floor, regardless of the point at which the raceway de- WARNING scends below or rises above the floor. KEEP 1.5 METERS CLEAR OF AIRCRAFT ENGINES AND FUEL TANK AREAS 513.9 Sealing. Seals shall be provided in accordance with (3) Cords. Flexible cords for aircraft energizers and 501.15 or 505.16, as applicable. Sealing requirements ground support equipment shall be identified for the type of specified shall apply to horizontal as well as to vertical service and extra-hard usage and shall include an equip- boundaries of the defined Class I locations. ment grounding conductor. 513.10 Special Equipment. (D) Mobile Servicing Equipment with Electrical (A) Aircraft Electrical Systems. Components. (1) General.Mobile servicing equipment(such as vacuum (1) De-energizing Aircraft Electrical Systems. Aircraft cleaners, air compressors, air movers)having electrical wir- electrical systems shall be de-energized when the aircraft is ing and equipment not suitable for Class 1, Division 2 or stored in a hangar and, whenever possible, while the air- Zone 2 locations shall be so designed and mounted that all craft is undergoing maintenance. such fixed wiring and equipment will be at least 450 mm (2) Aircraft Batteries. Aircraft batteries shall not be (18 in.)above the floor. Such mobile equipment shall not be charged where installed in an aircraft located inside or par- operated within the Class 1 location defined in 513.3(C)and shall carry at least one permanently affixed warning sign Bally inside a hangar. with the following words or equivalent: (B) Aircraft Battery Charging and Equipment. Battery WARNING chargers and their control equipment shall not be located or KEEP 5 FT CLEAR OF AIRCRAFT ENGINES operated within any of the Class l locations defined in AND FUEL TANK AREAS 513.3 and shall preferably be located in a separate building or in an area such as defined in 513.3(D). Mobile chargers or shall carry at least one permanently affixed warning sign WARNING with the following words or equivalent: KEEP 1.5 METERS CLEAR OF AIRCRAFT ENGINES WARNING AND FUEL TANK AREAS KEEP 5 FT CLEAR OF AIRCRAFT ENGINES (2) Cords and Connectors, Flexible cords for mobile AND FUEL TANK AREAS equipment shall be suitable for the type of service and or identified for extra-hard usage and shall include an equip- ment grounding conductor. Attachment plugs and recep- WARNING tacles shall be identified for the location in which they are KEEP 1.5 METERS CLEAR OF AIRCRAFT ENGINES installed and shall provide for connection of the equipment AND FUEL TANK AREAS grounding conductor. Tables, racks, trays, and wiring shall not be located (3) Restricted Use. Equipment that is not identified as within a Class I location and, in addition,shall comply with suitable for Class I, Division 2 locations shall not be oper- Article 480. ated in locations where maintenance operations likely to (C) External Power Sources for Energizing Aircraft. release flammable liquids or vapors are in progress. (1) Not Less Than 450 mm(18 in.)Above Floor.Aircraft (E) Portable Equipment. energizers shall be designed and mounted such that all elec- (1) Portable Lighting Equipment. Portable lighting trical equipment and fixed wiring will be at least 450 mm equipment that is used within a hangar shall be identified 2008 Edition NATIONAL ELECTRICAL CODE 70-409 513.12 ARTICLE 514—MOTOR FUEL DISPENSING FACILITIES for the location in which they are used. For portable lumi- rages. Only editorial changes were made to the extracted naires, flexible cord suitable for the type of service and text to make it consistent with this Code. identified for extra-hard usage shall be used. Each such cord shall include a separate equipment grounding conductor. 514.1 Scope.This article shall apply to motor fuel dispens- ing facilities, marine/motor fuel dispensing facilities, motor (2) Portable Utilization Equipment. Portable utilization fuel dispensing facilities located inside buildings, and fleet equipment that is or may be used within a hangar shall be vehicle motor fuel dispensing facilities. of a type suitable for use in Class I, Division 2 or Zone 2 locations. For portable utilization equipment, flexible cord FPN: For further information regarding safeguards for mo- suitable for the type of service and approved for extra-hard for fuel dispensing facilities,see NFPA 30A-2008,Cade for usage shall be used. Each such cord shall include a separate Motor Fuel Dispensing Facilities and Repair Garages. equipment grounding conductor. 514.2 Definition. 513.12 Ground-Fault Circuit-interrupter Protection for Motor Fuel Dispensing Facility. That portion of a prop- Personnel. All 125-volt, 50/60-Hz, single-phase, 15– and erty where motor fuels are stored and dispensed from fixed 20-ampere receptacles installed in areas where electrical equipment into the fuel tanks of motor vehicles or marine diagnostic equipment, electrical hand tools, or portable craft or into approved containers, including all equipment lighting equipment are to be used shall have ground-fault used in connection therewith. [30A•3.3.111 circuit-interrupter protection for personnel. FPN: Refer to Articles 510 and 51 I with respect to electri- 513.16 Grounding and Bonding Requirements. cal wiring and equipment for other areas used as lubritori- ums,service rooms,repair rooms,offices,salesrooms,com- (A) General Grounding Requirements, All metal race- pressor rooms, and similar locations. ways, the metal armor or metallic sheath on cables, and all non–current-carrying metal parts of fixed or portable elec- 514.3 Classification of Locations, trical equipment, regardless of voltage, shall be grounded. Grounding in Class I locations shall comply with 501.30 (A) Unclassified Locations. Where the authority having for Class I, Division 1 and 2 locations and 505.25 for Class jurisdiction can satisfactorily determine that flammable liq- I, Zone 0, I, and 2 locations. uids having a flash point below 38°C(100 0F), such as gaso- line, will not be handled, such location shall not be required (B) Supplying Circuits with Grounded and Grounding to be classified. Conductors in Class I Locations. (B) Classified Locations. (1) Circuits Supplying Portable Equipment or Pen- dants. Where a circuit supplies portables or pendants and (1) Class I Locations. Table 514.3(B)(1) shall be applied includes a grounded conductor as provided in Article 200, where Class I liquids are stored, handled, or dispensed and receptacles, attachment plugs, connectors, and similar de- shall be used to delineate and classify motor fuel dispens- vices shall be of the grounding type, and the grounded ing facilitics and commercial garages as defined in Article conductor of the flexible cord shall be connected to the 511. Table 515.3 shall be used for the purpose of delineat- screw shell of any lampholder or to the grounded terminal ing and classifying aboveground tanks. A Class I location of any utilization equipment supplied. shall not extend beyond an unpierced wall, roof, or other (2) Approved Means. Approved means shall be provided solid partition. [30A:8A, 8.31 for maintaining continuity of the grounding conductor be- (2) Compressed Natural Gas, Liquefied Natural Gas, tween the fixed wiring system and the non–current-carrying and Liquefied Petroleum Gas Areas. Table 514.3(B)(2) metal portions of pendant luminaires, portable luminaires, shall be used to delineate and classify areas where corn- and portable utilization equipment. pressed natural gas (CNG), liquefied natural gas (LNG), or liquefied petroleum gas (LPG) is stored, handled, or dis- pensed. Where CNG or LNG dispensers are installed be- neath a canopy or enclosure, either the canopy or the en- ARTICLE 514 closure shall be designed to prevent accumulation or entrapment of ignitible vapors, or all electrical equipment Motor Fuel Dispensing Facilities installed beneath the canopy or enclosure shall be suitable for Class 1,Division 2 hazardous(classified) locations. Dis- FPN: Rules that are followed by a reference in brackets pensing devices for liquefied petroleum gas shall be located contain text that has been extracted from NFPA 30A-2008, not less than 1.5 m (5 ft) from any dispensing device for Code for Motor Fuel Dispensing Facilities and Repair Ga- Class I liquids. [30A:12.1, 12.4, 12.51 70-410 NATIONAL.ELECTRICAL CODE 2WH Edition ARTICLE 514—MOTOR FUEL DISPENSING FACILITIES 514.3 FPN No. 1: For information on area classification where see NFPA 58-200$, Liquefied Petroleum Gas Code, and liquefied petroleum gases are dispensed, see NFPA 58- NFPA 59-2004, Utility LP-Gas Plant Code. 2008,Liquefied Petroleum Gas Code. FPN No. 3: See 555.21 for motor fuel dispensing stations FPN No. 2: For information on classified areas pertaining in marinas and boatyards. to LP-Gas systems other than residential or commercial, Table 514.3(B)(1) Class I Locations—Motor Fuel Dispensing Facilities Class 1, Group D Location Division Extent of Classified Location' Underground Tank Fill opening I Any pit or box below grade level, any part of which is within the Division 1 or Division 2, Zone I or Zone 2 classified location 2 Up to 450 mm (18 in.) above grade level within a horizontal radius of 3.0 m (10 ft) from a loose fill connection and within a horizontal radius of 1.5 m (5 ft) from a tight fill connection Vent—discharging upward I Within 900 mm (3 ft) of open end of vent, extending in all directions 2 Space between 900 mm (3 ft) and 1.5 m (5 ft) of open end of vent, extending in all directions Dispensing Device`•-" (except overhead type)' PITS 1 Any pit or box below grade level, any part of which is within the Division I or Division 2, Zone 1 or Zone 2 classified location Dispenser FPN: Space classification inside the dispenser enclosure is covered in ANSI/UL 87-1995, Power Operated Dispensing Devices for Petroleum Products. 2 Within 450 mm (18 in.) horizontally in all directions extending to grade from the dispenser enclosure or that portion of the dispenser enclosure containing liquid-handling components FPN: Space classification inside the dispenser enclosure is covered in ANSI/UL 87-1995,Power Operated Dispensing Devices for Petroleum Products. Outdoor 2 Up to 450 mm (18 in.) above grade level within 6.0 m (20 ft) horizontally of any edge of enclosure. Indoor 2 Up to 450 mm (18 in.) above grade or floor level within 6.0 m with mechanical ventilation (20 ft) horizontally of any edge of enclosure with gravity ventilation 2 Up to 450 mm (18 in.) above grade or floor level within 7.5 m (25 ft) horizontally of any edge of enclosure Dispensing Device-" Overhead type 3 I The space within the dispenser enclosure, and all electrical equipment integral with the dispensing hose or nozzle 2 A space extending 450 mm (18 in.) horizontally in all directions beyond the enclosure and extending to grade 2 Up to 450 mm (18 in.) above grade level within 6.0 m (20 ft) horizontally measured from a point vertically below the edge of any dispenser enclosure Remote Pump—Outdoor 1 Any pit or box below grade level if any part is within a horizontal distance of 3.0 in (10 ft) from any edge of pump 2 Within 900 mm (3 ft) of any edge of pump, extending in all directions.Also up to 450 mm (18 in.) above grade level within 3.0 m (10 ft) horizontally from any edge of pump Remote Pump—Indoor 1 Entire space within any pit 2 Within 1.5 m (5 ft)of any edge of pump, extending in all directions.Also tip to 900 mm (3 ft) above grade level within 7.5 m (25 ft) horizontally from any edge of pump (Continues) 2008 Edition NATIONAL ELFMRICAL CODE 70411 514.3 ARTICLE 514—MOTOR FUEL DISPENSING FACILITIES Table 514.3(B)(1) Continued Class I, Group D Location Division Extent of Classified Location' Lubrication or Service Room— Without 2 Entire area within any pit used for lubrication or similar services Dispensing where Class 1 liquids may be released 2 Area up to 450 mm (18 in.) above any such pit and extending a distance of 900 mm (3 ft) horizontally from any edge of the pit 2 Entire unventilated area within any pit, belowgrade area, or subfloor area 2 Area up to 450 mm (18 in.) above any such unventilated pit, belowgrade work area, or subfloor work area and extending a distance of 900 mm (3 ft) horizontally from the edge of any such pit, belowgrade work area, or subfloor work area Unclassified Any pit, belowgrade work area, or subfloor work area that is provided with exhaust ventilation at a rate of not less than 0.3 m'/minlm' (1 cfWft`) of floor area at all times that the building is occupied or when vehicles are parked in or over this area and where exhaust air is taken from a point within 300 mm (12 in.) of the floor of the pit, belowgrade work area, or subfloor work area Special Enclosure Inside Buildings 1 Entire enclosure Sales,Storage, and Rest Rooms Unclassified if there is any opening to these rooms within the extent of a Division 1 location, the entire room shall be classified as Division Vapor Processing Systems Pits 1 Any pit or box below grade level, any part of which is within a Division 1 or Division 2 classified location or that houses any equipment used to transport or process vapors Vapor Processing Equipment Located 2 Within any protective enclosure housing vapor processing Within Protective Enclosures equipment FPN: See 10.1.7 of NFPA 30A-2008. Code for Mater Fuel Dispensing Facilities and Repair Garages. Vapor Processing Equipment Not Within 2 The space within 450 mm (18 in.) in all directions of equipment Protective Enclosures (excluding piping containing flammable vapor or liquid extending to grade and combustion devices) level. Up to 450 mm (18 in.) above grade level within 3.0 m (10 ft) horizontally of the vapor processing equipment Equipment Enclosures l Any space within the enclosure where vapor or liquid is present under normal operating conditions Vacuum-Assist Blowers 2 The space within 450 mm (18 in.) in all directions extending to grade level. Up to 450 mot (18 in.) above grade level within 3.0 m (10 ft) horizontally 'For marine application,grade level means the surface of a pier extending down to water level. ''Refer to Figure 514.3 for an illustration of classified location around dispensing devices. 'Ceiling mounted hose reel. ;FPN: See 4.3.9 of NFPA 30A-2008, Code for Motor Fuel Dispensing Facilities and Repair Garages. 'FPN:Area classification inside the dispenser enclosure is covered in ANSI/UL 87-1995, Power-Operated Dispensing Devices for Petroleum Products. [30A:Table 8.3.11 70-412 NATIONAL ELECPRICAL CODE 2008 Edition ARTICLE 514—MOTOR FUEL DISPENSING FACILITIES 5143 Table 514.3(B)(2) Electrical Equipment Classified Areas for Dispensing Devices Extent of Classified Area Dispensing Device Class 1, Division 1 Class 1, Division 2 Compressed natural gas Entire space within the dispenser enclosure 1.5 m (5 ft) in all directions from dispenser enclosure Liquefied natural gas Entire space within the dispenser enclosure and From 1.5 m to 3.0 m (5 ft to 10 ft) in all 1.5 m (5 ft) in all directions from the directions from the dispenser enclosure dispenser enclosure Liquefied petroleum gas Entire space within the dispenser enclosure; Up to 450 mm (18 in.) aboveground and within 450 mm (18 in.) from the exterior surface of 6.0 m (20 ft) horizontally from any edge of the dispenser enclosure to an elevation of the dispenser enclosure, including pits or 1.2 m (4 ft) above the base of the dispenser; trenches within this area when provided the entire pit or open space beneath the with adequate mechanical ventilation dispenser and within 6.0 m (20 ft) horizontally from any edge of the dispenser when the pit or trench is not mechanically ventilated. [30A:Table 12.6.2] Class 1,Div.t 514.8 Underground Wiring. Underground wiring shall be D class 1,Div.2 installed in threaded rigid metal conduit or threaded steel Dispensing area 6.0 m(20 It) intermediate metal conduit.Any portion of electrical wiring 450 mm that is below the surface of a Class I, Division 1,or a Class � 450 mm 1, Division 2, location [as classified in Table 514.3(B)(1) � {18 in.} 450 mm and Table 514.30)(2)] shall be sealed within 3.05 m (10 ft) (18 in.) of the point of emergence above grade. Except for listed explosionproof reducers at the conduit seal, there shall be no union,coupling, box, or fitting between the conduit seal and the point of emergence above grade. Refer to Table 300.5. 6.0 in(20 ft) ;6.0 m;(20 ft) Exception No. l: Type M1 cable shall be permitted where it is installed in accordance with Article 332. Exception No. 2: Rigid nonmetallic conduit shall be per- Dispensers mitted where buried raider not less than 600 mm (2 ft) of cover. Where rigid nonmetallic conduit is used, threaded rigid metal conduit or threaded steel intermediate metal 6.0 m 6.0 m conduit shall be used or the last 600 mm 2 t o the (2a It) {2o It) .f ( f) f underground run to emergence or to the point of connection IV to the aboveground raceway, and an equipment grounding conductor shall be included to provide electrical continuity Figure 514.3 Classified Areas Adjacent to Dispensers as De- of the raceway system and for grounding of non—current- tailed in Table 514.3(B)(1). [30A:Figure 8.3.11 carrying metal parts. 514.4 Wiring and Equipment Installed in Class I Loca- 514.9 Sealing. tions.All electrical equipment and wiring installed in Class 1 locations as classified in 514.3 shall comply with the (A) At Dispenser. A listed seal shall be provided in each applicable provisions of Article 501. conduit run entering or leaving a dispenser or any cavities or enclosures in direct communication therewith. The seal- ing fitting shall be the first fitting after the conduit emerges FPN: For special requirements for conductor insulation, from the earth or concrete. see 501.20. (B) At Boundary. Additional seals shall be provided in 514.7 Wiring and Equipment Above Class I Locations. accordance with 501.15. Sections 501.15(A)(4) and (B)(2) Wiring and equipment above the Class I locations as clas- shall apply to horizontal as well as to vertical boundaries of sifted in 514.3 shall comply with 511.7. the defined Class I locations. 2008 Edition NATIONAL ELECTRICAL CODE 70 413 514.11 ARTICLE 515—BULK STORAGE PLANTS 514.11 Circuit Disconnects. bonded. Grounding and bonding in Class I locations shall (A) General.Each circuit leading to or through dispensing comply with 501.30. equipment, including equipment for remote pumping sys- tems, shall be provided with a clearly identified and readily accessible switch or other acceptable means, located remote ARTICLE 515 from the dispensing devices, to disconnect simultaneously from the source of supply, all conductors of the circuits, Bulk Storage Plants including the grounded conductor, if any. Single-pole breakers utilizing handle ties shall not be FPN: Rules that are followed by a reference in brackets permitted. contain text that has been extracted from NFPA 30-2008. Flammable and Combustible Liquids Code. Only editorial (B) Attended Self-Service Motor Fuel Dispensing Fa- changes were made to the extracted text to make it consis- cilities. Emergency controls as specified in 514.11(A) shall tent with this Code. be installed at a location acceptable to the authority having 515,1 Scope. This article covers a property or portion of a jurisdiction, but controls shall not be more than 30 m (100 ft) property where flammable liquids are received by tank ves- from dispensers. [30A:6.7.11 sel, pipelines, tank car, or tank vehicle and are stored or (C) Unattended Self-Service Motor Fuel Dispensing Fa- blended in bulk for the purpose of distributing such liquids cilities. Emergency controls as specified in 514.11(A) shall by tank vessel, pipeline, tank car, tank vehicle, portable be installed at a location acceptable to the authority having tank, or container. jurisdiction, but the control shall be more than 6 m (20 ft) 515.2 Definition. but less than 30 m (100 ft) from the dispensers. Additional emergency controls shall be installed on each group of dis- Bulk Plant or Terminal. That portion of a property where pensers or the outdoor equipment used to control the dis- liquids are received by tank vessel, pipelines, tank car, or pensers. Emergency controls shall shut off all power to all tank vehicle and are stored or blended in bulk for the pur- dispensing equipment at the station. Controls shalt be pose of distributing such liquids by tank vessel, pipeline, manually reset only in a manner approved by the authority tank car, tank vehicle, portable tank, or container. having jurisdiction. [30A:6.7.21 [30:3.3.32.1] FPN: For additional information, see 6.7.1 and 6.7.2 of FPN: For further information, see NFPA 30-2008, Flam- NFPA 30A-2008, Code for Motor Fuel Dispensing Facili- ratable and Combustible Liquids Code. ties and Repair Garages. 515.3 Class I Locations. Table 515.3 shall be applied where Class I liquids are stored, handled, or dispensed and 514.13 Provisions for Maintenance and Service of Dis- penning Equipment. Each dispensing device shall be pro- shall be used to delineate and classify bulk storage plants.vided with a means to remove all external voltage sources, The class location shall not extend beyond a floor, wall, includin roof, or other solid partition that has no communicating g feedback, during periods of maintenance and ser- openings. 130:8.1, 8.2.21 vice of the dispensing equipment. The location of this means shall be permitted to be other than inside or adjacent FPN No. 1: The area classifications listed in 'fable 515.3 to the dispensing device. The means shall be capable of are based on the premise that the installation meets the being locked in the open position. applicable requirements of NFPA 30-2008, Flammable and Combustible Liquids Code, Chapter 5, in all respects. Should this not be the case, the authority having jurisdic- 514,16 Grounding and Bonding. All metal raceways, the tion has the authority to classify the extent of the classified metal armor or metallic sheath on cables, and all non– space. current-carrying metal parts of fixed portable electrical FPN No. 2: See 555.21 for gasoline dispensing stations in equipment, regardless of voltage, shall be grounded and marinas and boatyards. 70-414 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 515--HULK STORAGE PLANTS 515.3 Table 5I5.3 Electrical Area Classifications NEC Class I Location Division Zone Extent of Classified Area Indoor equipment installed in accordance with 1 0 The entire area associated with such equipment Section 5.3 of NFPA 30 where flammable where flammable gases or vapors are vapor—air mixtures can exist under normal present continuously or for long periods of operation time I Area within 1.5 m (5 ft) of any edge of such equipment, extending in all directions 2 2 Area between 1.5 m and 2.5 m (5 ft and 8 ft) of any edge of such equipment,extending in all directions; also, space up to 900 mm (3 ft)above floor or grade level within 1.5 m to 7.5 m (5 ft to 25 ft) horizontally from any edge of such equipment' Outdoor equipment of the type covered in 1 0 The entire area associated with such equipment Section 5.3 of[NFPA 30 where flammable where flammable gases or vapors are present vapor—air mixtures may exist under normal continuously or for long periods of time operation 1 1 Area within 900 mm(3 ft) of any edge of such equipment,extending in all directions 2 2 Area between 900 mm (3 ft) and 2.5 m(8 ft)of any edge of such equipment,extending in all directions; also,space up to 900 mm(3 ft) above floor or grade level within 900 mm to 3.0 m (3 ft to 10 ft)horizontally from any edge of such equipment Tank storage installations inside buildings I I All equipment located below grade level 2 2 Any equipment located at or above grade level Tank--aboveground 1 0 Inside fixed roof tank 1 Area inside dike where dike height is greater than the distance from the tank to the dike for more than 50 percent of the tank circumference Shell,ends,or roof and dike area 2 2 Within 3.0 m (10 ft)from shell,ends,or roof of tank;also,area inside dike to level of top of tank Vent 1 0 Area inside of vent piping or opening 1 l Within 1.5 m (5 ft)of open end of vent, extending in all directions 2 2 Area between 1.5 m and 3.0 in(5 ft and 10 ft) from open end of vent,extending in all directions Floating roof with fixed outer roof 1 0 Area between the floating and fixed roof sections and within the shell Floating roof with no fixed outer roof l I Area above the floating roof and within the shell Underground tank fill opening 1 I Any pit,or space below grade level, if any part is within a Division 1 or 2,or Zone I or 2, classified location 2 2 Up to 450 mm(18 in.)above grade level within a horizontal radius of 3.0 m(10 ft) from a loose fill connection,and within a horizontal radius of 1.5 m(5 ft)from a tight fill connection Vent—discharging upward 1 0 Area inside of vent piping or opening I 1 Within 900 mm (3 lt)of open end of vent, extending in all directions r Continues) 2008 Edition NATIONAL ELECTRICAL CODE 70-415 515.3 ARTICLE 515—BULK STORAGE PLANTS Table 515.3 Continued NEC Class I Location Division Zone Extent of Classified Area Vent—discharging upward (cortt'd.) 2 2 Area between 900 mm and 1.5 m (3 ft and 5 ft) of open end of vent, extending in all directions Drum and container tilling —outdoors or indoors l t} Area inside the drum or container I I Within 900 mm (3 f) of vent and fill openings, extending in all directions 2 2 Area between 900 mm and 1.5 In (3 ft and 5 ft) from vent or fill opening. extending in all directions; also, up to 450 mm (18 in.) above floor or grade level within a horizontal radius of 3.0 m (10 ft) from vent or fill opening Pumps, bleeders, withdrawal fittings Indoors 2 2 Within 1.5 m (5 ft) of any edge of such devices, extending in all directions; also, up to 900 mm (3 ft) above floor or grade level within 7,5 m (25 ft) horizontally from any edge of such devices Outdoors 2 2 Within 900 mm (3 ft) of any edge of such devices, extending in all directions.Also, up to 450 mm (18 in.) above grade level within 3.0 m (10 ft) horizontally from any edge of such devices Pits and sumps Without mechanical ventilation 1 1 Entire area within a pit or sump if any pan is within a Division 1 or 2, or Zone 1 or 2, classified location With adequate mechanical ventilation 2 2 Entire area within a pit or sump if any part is within a Division 1 or 2, or Zone 1 or 2, classified location Containing valves, fittings, or piping. and not 2 2 Entire pit or sump within a Division 1 or 2, or Zone 1 or 2, classified location Drainage ditches, separators, impounding basins Outdoors 2 2 Area up to 450 mm (18 in.) above ditch, separator. or basin; also, area up to 450 mm (18 in.) above grade within 4.5 m (15 ft) horizontally from any edge Indoors Same classified area as pits Tank vehicle and tank car` loading through open I (} Area inside of the tank dome I I Within 900 mm (3 ft) of edge of dome, extending in all directions 2 2 Area between 900 mm and 4.5 m (3 ft and 15 ft) from edge of dome, extending in all directions Loading through bottom connections with l 0 Area inside of the tank atmospheric venting I I Within 900 mm (3 ft) of point of venting to atmosphere, extending in all directions 2 2 Area between 900 mm and 4.5 m (3 ft and 15 ft) from point of venting to atmosphere, extending in all directions; also, up to 450 mm (18 in.) above grade within a horizontal radius of 3.0 m (10 ft) from point of loading connection 7"16 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 515—SULK STORAGE PLANTS 515.3 Table 515.3 Continued NEC Class I Location Division Zone Extent of Classified Area Office and rest rooms Unclassified If there is any opening to these rooms within the extent of an indoor classified location, the room shall be classified the same as if the wall, curb, or partition did not exist. Loading through closed dome with atmospheric I I Within 900 mm (3 ft) of open end of vent, venting extending in all directions 2 2 Area between 900 mm and 4.5 m (3 ft and 15 ft) from open end of vent, extending in all directions, also, within 900 mm Q ft) of edge of dome, extending in all directions Loading through closed dome with vapor control 2 2 Within 900 mm (3 ft) of point of connection of both fill and vapor lines extending in all directions Bottom loading with vapor control or any bottom 2 2 Within 900 mm (3 ft) of point of connections, unloading extending in all directions also up to 450 mm (18 in.) above grade within a horizontal radius of 3.0 m (10 ft) from point of connections Storage and repair garage for tank vehicles I I All pits or spaces below floor level 2 2 Area up to 450 mm (18 in.) above floor or grade level for entire storage or repair garage Garages for other than tank vehicles Unclassified if there is any opening to these rooms within the extent of an outdoor classified location, the entire room shall be classified the same as the area classification at the paint of the opening. Outdoor drum storage Unclassified Inside rooms or storage lockers used for the 2 2 Entire room storage of Class I liquids Indoor warehousing where there is no flammable Unclassified If there is any opening to these rooms within liquid transfer the extent of an indoor classified location, the room shall be classified the same as if the wall, curb, or partition did not exist. Piers and wharves See Figure 515.3. 'The release of Class I liquids may generate vapors to the extent that the entire building,and possibly an area surrounding it,should be considered a Class 1, Division 2 or Zone 2 location. 2When classifying extent of area,consideration shall be given to fact that tank cars or tank vehicles may be spotted at varying points. Therefore, the extremities of the loading or unloading positions shall be used. [30:Table 8.2.2] 2008 Edition NATIONAL ELECTRICAL CODE 70-417 515.4 ARTICLE 515—BULK STORAGE PLANTS 4—15 in(50 ft) 1 15 m(50 ft) 7.5 m 7.5 m I Deck (25 ft) 4(25 ft) 75m t (25 fl) Open sump to deck for Operating envelope draining lines and hoses and slated position of loading arms or Ir hoses I -K---15m(50fl) 600 mm (2 R) 7 5 m 5 It i Moroach pier Share Waler level ®Division 1 ®Division 2 =Unclassified Notes: (1)The'source of vapor'shall be the operating envelope and stored position of the outboard flange connection of the loading arm(or hose). (2)The berth area adjacent to tanker and barge cargo tanks is la be Division 2 to the following extent: a.7.6 m(25 11)horizontally in all directions on the pier side from that portion of the hull containing cargo tanks b From the water level to 7.6 m(25 R)above the cargo lanks at their highest position (3)Additional locations may have to be classified as required by the presence of other sources of flammable liquids on the berth,by Coast Guard,or other regulations. Figure 515.3 Marine Terminal Handling Flammable Liquids. [30:Figure 7.7.161 515.4 Wiring and Equipment Located in Class I Loca- (C) Portable Luminaires or Other Utilization Equip- tions. All electrical wiring and equipment within the Class ment. Portable luminaires or other utilization equipment I locations defined in 515.3 shall comply with the appli- and their flexible cords shall comply with the provisions of cable provisions of Article 501 or Article 505 for the divi- Article 501 or Article 505 for the class of location above sion or zone in which they are used. which they are connected or used. Exception: As permitted in 515.8. 515.8 Underground Wiring. 515.7 Wiring and Equipment Above Class I Locations. (A) Wiring Method. Underground wiring shall be in- (A) Fixed Wiring. All fixed wiring above Class I locations stalled in threaded rigid metal conduit or threaded steel shall be in metal raceways, Schedule SO PVC conduit,Type intermediate metal conduit or, where buried under not less RTRC marked with the suffix-XW, or Type MI,TC,or MC than 600 mm (2 ft) of cover, shall be permitted in rigid cable. nonmetallic conduit or a listed cable. Where rigid nonme- tallic conduit is used, threaded rigid metal conduit or (B) Fixed Equipment. Fixed equipment that may produce threaded steel intermediate metal conduit Shall be used for arcs, sparks, or particles of hot metal, such as lamps and the last 600 mm(2 ft) of the conduit run to emergence or to lampholders for fixed lighting, cutouts, switches, recep- the point of connection to the aboveground raceway.Where tacles, motors, or other equipment having make-and-break cable is used, it shall be enclosed in threaded rigid metal or sliding contacts, shall be of the totally enclosed type or conduit or threaded steel intermediate metal conduit from be constructed so as to prevent the escape of sparks or hot the point of lowest buried cable level to the point of con- metal particles. nection to the aboveground raceway. 70-418 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 516—SPRAY APPLICATION.DIPPING,AND COATING PROCESSES 516.3 (B) Insulation. Conductor insulation shall comply with signs, and maintenance, see NFPA 33-2007, Standard for 501.20. Spray Application Using Flammable and Combustible Ma- terials, and NFPA 34-2007, Standard for Dipping and (C) Nonmetallic Wiring.Where rigid nonmetallic conduit Coating Processes Using Flammable or Combustible Liq- or cable with a nonmetallic sheath is used, an equipment uids. For additional information regarding ventilation, see grounding conductor shall be included to provide for elec- NFPA 91-2004,Standard for Exhaust Systems for Air Con- yeying of{vapors, Gases, Mists, and Noncombustible Par- ticulate continuity of the raceway system and for grounding Solids. of non–current-carrying metal parts. 515.9 Sealing. Sealing requirements shall apply to hori- 516.2 Definitions. For the purpose of this article, the fol- zontal as well as to vertical boundaries of the defined Class lowing definitions shall apply, I locations. Buried raceways and cables under defined Class Spray Area.Normally,locations outside of buildings or local- I locations shall be considered to be within a Class I, Divi- ized operations within a larger room or space. Such are nor- sion 1 or Zone 1 location. mally provided with some local vapor extraction/ventilation system. In automated operations, the area limits shall he the 515.10 Special Equipment — Gasoline Dispensers. maximum area in the direct path of spray operations. In Where gasoline or other volatile flammable liquids or liq- manual operations,the area limits shall be the maximum area uefied flammable gases are dispensed at bulk stations, the of spray when aimed at 180 degrees to the application surface. applicable provisions of Article 514 shall apply. Spray Booth. An enclosure or insert within a larger room 515.16 Grounding and Bonding. All metal raceways, the used for spray/coating/dipping applications. A spray booth metal armor or metallic sheath on cables, and all non– may be fully enclosed or have open front or face and may current-carrying metal parts of fixed or portable electrical include separate conveyor entrance and exit. The spray equipment, regardless of voltage, shall be grounded and booth is provided with a dedicated ventilation exhaust but bonded as provided in Article 250. may draw supply air from the larger room or have a dedi- Grounding and bonding in Class i locations shall com- cated air supply. ply with 501.30 for Class I, Division I and 2 locations and 505.25 for Class I, Zone 0, 1, and 2 locations. Spray Room. A purposefully enclosed room built for spray/coating/dipping applications provided with dedicated see 4.5.3.4 and 4.5.3.5 of NFPA 30-2008, Flammable and Far information on grounding For static protection, ventilation supply and exhaust. Normally the room is con- see Combustible Liquids Code. figured to house the item to be painted, providing reason- able access around the item/process. Depending on the size of the item being painted, such rooms may actually be the entire building or the major portion thereof. ARTICLE 516 516.3 Classification of Locations. Classification is based Spray Application, Dipping, on dangerous quantities of flammable vapors, combustible and Coating Processes mists, residues, dusts, or deposits. (A) Class 1,Division 1 or Class I,Zone 0 Locations.The FPN: Rules that are followed by a reference in brackets following spaces shall be considered Class 1, Division 1, or contain text that has been extracted from NFPA 33-2007, Class 1, Zone 0, as applicable: Standard for Spray Application Using Flammable and Combustible Materials, or NFPA 34-2007, Standard for (1) The interior of any open or closed container of a flam- Dipping and Coating Processes Using Flammable or Com- mable liquid bustible Liquids. Only editorial changes were made to the (2) The interior of any dip tank or coating tank extracted text to make it consistent with this Code. FPN: For additional guidance and explanatory diagrams, 516.1 Scope. This article covers the regular or frequent see 4.3.5 of NFPA 33-2007,Standard for Spray Application application of flammable liquids, combustible liquids, and Using Flammable or Combustible Materials, and Sections combustible powders by spray operations and the applica- 4.2, 4.3, and 4.4 of NFPA 34-2007, Standard for Dipping tion of flammable liquids, or combustible liquids at tem- and Coating Processes Using Flammable or Combustible peratures above their flashpoint, by dipping, coating, or Liquids. other means. (B) Class 1 or Class 11,Division I Locations.The follow- FPN: For further information regarding safeguards for ing spaces shall be considered Class I, Division 1, or Class these processes,such as fire protection, posting of warning 1, Zone 1, or Class 11, Division 1 locations, as applicable: 2008 Edition NATIONAL ELECTRICAL.CODE 70--419 516.3 ARTICLE 516—SPRAY APPLICATION.DIPPING,AND COATING PROCESSES (1) The interior of spray booths and rooms except as spe- cifically provided in 516.3(D). (2) The interior of exhaust ducts. Spray area (3) Any area in the direct path of spray operations. (4) For open dipping and coating operations, all space 6720 mm (22 ft) within a 1.5-m (5-ft) radial distance from the vapor sources extending from these surfaces to the floor. The vapor source shall be the liquid exposed in the process and the drainboard, and any dipped or coated object from which it is possible to measure vapor concentra- Top(plan) tions exceeding 25 percent of the lower flammable limit at a distance of 300 mm (I ft), in any direction, from the object. Roof (5) Sumps, pits, or belowgrade channels within 7.5 m (25 ft) horizontally of a vapor source. If the sump, pit, 3050 m Spray area or channel extends beyond 7.5 m (25 ft) from the vapor (io ft) source, it shall be provided with a vapor stop or it shall be classified as Class I, Division I for its entire length. (6) All space in all directions outside of but within 900 mm (3 ft) of open containers, supply containers, spray gun ' Front(elevation) cleaners, and solvent distillation units containing flam- mable liquids. Class I, Division i;Class I,Zone i; (C) Class I or Class ll,Division 2 Locations.The follow- or Class If,Division 1 ing spaces shall be considered Class I, Division 2, or Class ® Class I, Division 2;Class I,Zone 2; I, Zone 2, or Class II, Division 2 as applicable. or Class n,Division 2 Figure 516.3(0)(1) Electrical Area Classification for Open (1} Open Spraying. For open spraying, all space outside Spray Areas. (33:1~igure 6.5.1] of but within 6 m (20 ft) horizontally and 3 m (10 ft) vertically of the Class 1, Division I or Class I, Zone 1 For the purposes of this subsection, interlocked shall location as defined in 516.3(A), and not separated from it mean that the spray application equipment cannot be oper- by partitions. See Figure 516.3(C)(1), [33:6.5.11 ated unless the exhaust ventilation system is operating and (2) Closed-Top, Open-Face, and Open-Front Spraying. functioning properly and spray application is automatically If spray application operations are conducted within a stopped if the exhaust ventilation system fails. [33:6.5.2.2] closed-top, open-face, or open-front booth or room, any (3) Open-Top S For spraying operations con- electrical wiring or utilization equipment located outside of p p p ra m y g' p ra i y g p ducted within an open top spray booth, the space 900 mm the booth or room but within the boundaries designated as Division 2 or Zone 2 in Figure 516.3(0)(2)shall be suitable (3 ft) vertically above the booth and within 900 mm (3 ft) for Class 1, Division 2, Class I, Zane 2, or Class II, Divi- of other booth openings shall be considered Class 1, Divi- Sion 2; Class I, Zone 2; or Class II, Division 2. [33:6.5.31 sion 2 locations, whichever is applicable. The Class 1, Di- vision 2, Class I, Zone 2, or Class I1, Division 2 locations (4) Enclosed Booths and Rooms.For spraying operations shown in Figure 516.3(C)(2) shall extend from the edges of confined to an enclosed spray booth or room, the space the open face or open front of the booth or room in accor- within 900 mm (3 ft) in all directions from any openings dance with the following: shall be considered Class 1, Division 2; or Class 1, Zone 2; (a) If the exhaust ventilation system is interlocked with or Class 11, Division 2 as shown in Figure 516.3(C)(4). the spray application equipment, the Division 2 or Zone 2 [33:6.5.41 location shall extend 1.5 m (5 ft) horizontally and 900 mm (5) Dip Tanks and Drain Boards—Surrounding Space. (3 ft) vertically from the open face or open front of the For dip tanks and drain boards, the 914-mm (3-ft) space booth or room, as shown in Figure 516.3(C)(2), top. surrounding the Class I, Division 1 or Class I, Zone 1 (b) If the exhaust ventilation system is not interlocked location as defined in 516.3(A)(4) and as shown in Figure with the spray application equipment, the Division 2 or 516.3(C)(5). [34.6.4.4] Zone 2 location shall extend 3 m (10 ft) horizontally and 900 mm(3 ft) vertically from the open face or open front of (6) Dip Tanks and Drain Boards—Space Above Floor. the booth or room,as shown in Figure 516.3(C)(2),bottom. For dip tanks and drain boards, the space 900 mm (3 ft) 70-420 NATIONAL ELECTRICAL CODE. 2008 Edition ARTICLE 516—SPRAY APPLICATION, DIPPING.AND COATING PROCESSES 516.3 1525 mm(5 ft)radius 915 mm(3 ft)radius Extent of Class I or 900 mm R Class II,Division 2 area -, 915 mm{3 ft)radius 915 mm(3 ft)radius (3 ft) :-� r 900 mm R (3 ft) 915 mm (3 ft)radius ; Enclosed spray 915 mm(3 ft)radius ; I-__ booth or room `915 mm(3 ft)radius Conveyor (Class[.Division 1 or opening Class II,Division 1 within) / Open face -------- ---- 1525 mm (5 ft)radius 900 mm R (3 ft} Plan view 900 mm R 3050 m(10 ft)radius (3 ft) 915 mm(3 ft)radius l 915 mm 3 ft radius 900 mm R(3 ft) 900 mm R(3 ft) ( ) 915 mm(3 ft)radius 900mmR 915 mm (3 ft)radius 'y 915 915 mm(3 ft)radius -"FConveyor Elevation ,915 mm{3 ft}radius,`, ­­,!opening Figure 516.3(C)(4) Class 1, Division 2, Class 1, Zone 2, or \ Class Il, Division 2 Locations Adjacent to an Enclosed Spray Booth or Spray Doom. [33:Figure 6.5.4] Open ------------3050 m face (1Ott)radius -------)Iid Figure 516.3(C)(2) Class I, Division 2, Class 1, Zone 2, or Class II,Division 2 Locations Adjacent to a Closed Top,Open Face, or Open Front Spray Booth or Room. [33:Figures 6.5.2(a) and 6.5.2(b)] 1525 Point beyond which object 1525 mm {5 ft}) is no longer a vapor source 915 mm (5 ft) as defined in 516.3(13)(4) Conveyor rail (3 ft) 915 mm (3 ft) _ _'J 1525 mm 915 mm (5 ft) 915 mm (3 ft) La (3 ft) Diptank a < •. ., .� .,. ��.."" ���� . . ., Floor � Pit p,, _ 915 mm Drainboard �►I 915 mm(3 ft) (3 ft) 1525 mm 1525 mm 61 DO mm(20 ft) 1525 mm (5 ft) {5 ft) 61 DD mm(20 ft) (5 ft) ® Class I,Division 1 or Zone 0 0 Class I,Division 1 or Zone 1 ® Class[.Division 2 or Zone 2 Figure 516.3(C)(5) Electrical Area Classification for Open Processes Without Vapor Containment or Ventilation. [34:Figure 6.4(a)] 2008 Edition NATIONAL ELECTRICAL CODE 70-421 516.4 ARTICLE 516—SPRAY APPLICATION, DIPPING.AND COATING PROCESSES above the floor and extending 6 m (20 ft) horizontally in all (B) Wiring and Equipment — Vapors and Residues. directions from the Class I, Division 1 or Class 1, Zone 1 Unless specifically listed for locations containing deposits location. of dangerous quantities of flammable or combustible va- pors, mists, residues, dusts, or deposits (as applicable), E.rreptivtt: This space shall not be required to be corrsid there shall be no electrical equipment in any spray area as eyed a hazardous (classified) location where the vapor source area is 0.46 m" (S.ft`)or less and where the contents herein defined whereon deposits of combustible residue of the open tank trough or container do not exceed 19 L may readily accumulate, except wiring in rigid metal con- (5 gal). In addition, the vapor concentration during opera- duit, intermediate metal conduit,Type MI cable, or in metal tion and shutdown periods shall not exceed 25 percent of boxes or fittings containing no taps, splices, or terminal the lower flaninurble lintit outside the Class I location connections. [33:6.4.2] specified in 516.3(B)(4). [34:6.4.4 Exception] (C) Illumination. Illumination of readily ignitible areas (7) Open Containers. All space in all directions within through panels of glass or other transparent or translucent 600 mm (2 ft) of the Division I or Zone 1 area surrounding material shall be permitted only if it complies with the open containers, supply containers, spray gun cleaners, and following: solvent distillation units containing flammable liquids, as (1) Fixed lighting units are used as the source of illumina- well as the area extending 1.5 m (5 ft) beyond the Division [ion. 1 or Zone 1 area up to a height of 460 mm (18 in.) above (2) The panel effectively isolates the Class I location from the floor or grade level. [33:6.6.2] the area in which the lighting unit is located. (D) Enclosed Coating and Dipping Operations. The (3) The lighting unit is identified for its specific location. space adjacent to an enclosed dipping or coating process or (4) The panel is of a material or is protected so that break- apparatus shall be considered unclassified. [34:6.5.3] age is unlikely. (5) The arrangement is such that normal accumulations of Exception: The space within 900 mm (3 ft) in all directions hazardous residue on the surface of the pane[ will not from aril• opening in the enclosures shall be c•fassified as be raised to a dangerous temperature by radiation or Class 1, Division 2 or Class !, "Lune 2, as applicable. [34:6.5.21 conduction from the source of illumination. (D) Portable Equipment. Portable electric luminaires or (E) Adjacent Locations. Adjacent locations that are cut other utilization equipment shall not be used in a spray area oil from the defined Class I or Class II locations by tight during spray operations. partitions without communicating openings, and within which flammable vapors or combustible powders are not Exception No. 1: Where portable electric luminaires are likely to be released, shall be unclassified. required for operations in spaces not readily illuminated by fixed lighting within the spraying area, they.shall be of the (F) Unclassified Locations. Locations using drying, cur- type identified for Class 1, Division I or Class 1, Zone 1 ing, or fusion apparatus and provided with positive me- locations where readily ignitible residues nary be present. chanical ventilation adequate to prevent accumulation of [33:6.9 Exception] flammable concentrations of vapors, and provided with ef- fective interlocks to de-energize all electrical equipment Exception No. 2: Where portable electric drying apparatus (other than equipment identified for Class I locations) in is used in automobile refinishing spry} booths curd the fvl case the ventilating equipment is inoperative, shall be per- lowing requirements are met: mitted to be unclassified where the authority having juris- (a) The apparatus and its electrical connections are not diction so judges. located within the spray enclosure during sera}•operations. FPN: For further information regarding safeguards, see (b) Electrical equipment within 450 mm (18 in.) of the NFPA 86-2007.Standard for Ovens and Furnaces. floor is identified for Class I, Division 2 or Class I, Zone 2 locations. 516.4 Wiring and Equipment in Class I Locations. (c) All metallic parts of the drying apparatus are elec- trically bonded curd grounded. (A) Wiring and Equipment—Vapors. All electrical wir- (d) Interlocks core provided to prevent the operation of ing and equipment within the Class I location (containing spray equipment while drvit><s;apparatus is within the spray vapor only — not residues) defined in 516.3 shall comply enclosure, to allow for a 3-minute purge of the enclosure with the applicable provisions of Article 501 or Article 505, before energizing the drying apparatus and to shut off drT as applicable. ing apparatus on failure of ventilation system. 70422 NATIONAL ELECTRICAL CODE, 2008 Edition ARTICLE 516--SPRAY APPLICATION,DIPPING,AND COATING PROCESSES 516.10 (E) Electrostatic Equipment. Electrostatic spraying or (2) Electrostatic Equipment. Electrodes and electrostatic detearing equipment shall be installed and used only as atomizing heads shall be adequately supported in perma- provided in 516.10. nent locations and shall be effectively insulated from FPN: For further information, see NFPA 33-2007, Stan- ground. Electrodes and electrostatic atomizing heads that are dard for Spray Application Using Flaininable or Con:bus- permanently attached to their bases,supports,reciprocators,or tible Materials. robots shall be deemed to comply with this section. (3) High-Voltage Leads. High-voltage leads shall be prop- 516.7 Wiring and Equipment Not Within Class I and II erly insulated and protected from mechanical damage or Locations. exposure to destructive chemicals. Any exposed element at (A) Wiring. All fixed wiring above the Class I and II lo- high voltage shall be effectively and permanently supported cations shall be in metal raceways, rigid nonmetallic con- on suitable insulators and shall be effectively guarded duit, or electrical nonmetallic tubing, or shall be Type MI, against accidental contact or grounding. TC, or MC cable. Cellular metal floor raceways shall be (4) Support of Goods. Goods being coated using this pro- permitted only for supplying ceiling outlets or extensions to cess shall be supported on conveyors or hangers. The con- the area below the floor of a Class I or 11 location, but such veyors or hangers shall be arranged (1) to ensure that the raceways shall have no connections leading into or through parts being coated are electrically connected to ground with the Class I or II location above the floor unless suitable a resistance of I megohm or less and (2) to prevent parts seals are provided. from swinging. (B) Equipment.Equipment that may produce arcs, sparks, (5) Automatic Controls. Electrostatic apparatus shall be or particles of hot metal,such as lamps and lampholders for equipped with automatic means that will rapidly de- fixed lighting, cutouts, switches, receptacles, motors, or energize the high-voltage elements under any of the follow- other equipment having make-and-break or sliding con- ing conditions: tacts,where installed above a Class I or 1I location or above (1) Stoppage of ventilating fans or failure of ventilating a location where freshly finished goods are handled, shall equipment from any cause be of the totally enclosed type or be constructed so as to (2) Stoppage of the conveyor carrying goods through the prevent the escape of sparks or hot metal particles. high-voltage field unless stoppage is required by the 516.10 Special Equipment. spray process (3) Occurrence of excessive current leakage at any point in (A) Fixed Electrostatic Equipment.This section shall ap- the high-voltage system ply to any equipment using electrostatically charged ele- (4) De-energizing the primary voltage input to the power ments for the atomization, charging, and/or precipitation of supply hazardous materials for coatings on articles or for other similar purposes in which the charging or atomizing device (6) Grounding, All electrically conductive objects in the is attached to a mechanical support or manipulator. This spray area, except those objects required by the process to shall include robotic devices.This section shall not apply to be at high voltage, shall be adequately grounded. This re- devices that are held or manipulated by hand. Where robot re- quirement shall apply to paint containers, wash cans, or programming procedures involve manual manipulation guards, hose connectors, brackets, and any other electri- cally conductive objects or devices in the area, of the robot arm while spraying with the high voltage on, the provisions of 516.10(B) shall apply. The installation of FPN: For more information on grounding; and bonding for electrostatic spraying equipment shall comply with Static eleciricity purposes,see NFPA 33-2007,,Standard for 516.10(A)(1) through (A)(10). Spray equipment shall be Spray Application Using Flammable or Combustible Mate. listed. All automatic electrostatic equipment systems shall rials; NFPA 34-2007, Standard far Dipping and Coating Processes ❑sthg ,Flammable or Combustible Liquids, and comply with 516.4(A}(1) through (A}(9). NFPA 77-2007, Recommended Practice on Static (1) Power and Control Equipment. Transformers, high- Electricity. voltage supplies, control apparatus, and all other electrical (7) Isolation.Safeguards such as adequate booths, fencing, portions of the equipment shall be installed outside of the railings, interlocks, or other means shall be placed about Class I location as defined in 516.3 or be of a type identi- the equipment or incorporated therein so that they,either by fied for the location. their location, character, or both, ensure that a safe separa- Exception: High-voltage grids, electrodes, electrostatic at- tion of the process is maintained. omizing heads, and their connections shall be permitted (8) Signs. Signs shall be conspicuously posted to convey within the Class I location. the following: 2006 Edition NATIONAL ELECTRICAL CODE 70-423 516.10 ARTICLE 516—SPRAY APPLICATION, DIPPING,AND COATING PROCESSES (1) Designate the process zone as dangerous with regard to other persons entering the spray area shall be conspicuously fire and accident posted. (2) Identify the grounding requirements for all electrically (4) Electrostatic Equipment. All electrically conductive conductive objects in the spray area objects in the spraying area shall be adequately grounded. (3) Restrict access to qualified personnel only This requirement shall apply to paint containers,wash cans, (9) Insulators. All insulators shall be kept clean and dry, and any other electrical conductive objects or devices in the area. The equipment shall carry a prominent, permanently (I0) Other Than Nonincendive Equipment.Spray equip- installed warning regarding the necessity for this grounding ment that cannot be classified as nonincendive shall comply feature. with (A)(10)(a) and (A)(10)(b). FPN: For more information on grounding and bonding for (a) Conveyors or hangers shall be arranged so as to static electricity purposes,see NFPA 33-2007,Standard.jor Spray Application Using Flammable or Combustible Mate. maintain a safe distance of at least twice the sparking dis- rials; NFPA 34-2007, Standard for Dipping and Coating tance between goods being painted and electrodes, electro- Processes Using Flammable or Combustible Liquids; and static atomizing heads, or charged conductors. Warnings NFPA 77-2007, Recommended Practice on Static defining this safe distance shall be posted. [33:11.4.11 Electricity. (b) The equipment shall provide an automatic means (5) Support of Objects. Objects being painted shall be of rapidly de-energizing the high-voltage elements in the maintained in metallic contact with the conveyor or other event the distance between the goods being painted and the grounded support. Hooks shall be regularly cleaned to en- electrodes or electrostatic atomizing heads falls below that sure adequate grounding of I megohm or less. Areas of specified in (a). [33:11.3.81 contact shall be sharp points or knife edges where possible. Points of support of the object shall be concealed from (B) Electrostatic Hand-Spraying Equipment. This sec- random spray where feasible; and, where the objects being tion shall apply to any equipment using electrostatically sprayed are supported from a conveyor,the point of attach- charged elements for the atomization, charging, and/or pre- ment to the conveyor shall be located so as to not collect cipitation of materials for coatings on articles, or for other spray material during normal operation. 133• Chapter 12] similar purposes in which the atomizing device is hand- held or manipulated during the spraying operation. Electro- (C) Powder Coating.This section shall apply to processes static hand-spraying equipment and devices used in con- in which combustible dry powders are applied.The hazards nection with paint-spraying operations shall be of listed associated with combustible dusts are present in such a types and shall comply with 516.10(B)(1) through (13)(5)• process to a degree, depending on the chemical composi- (I) General.The high-voltage circuits shall be designed so tion of the material, particle size, shape, and distribution. as not to produce a spark of sufficient intensity to ignite the (1) Electrical Equipment and Sources of Ignition. Elec- most readily ignitible of those vapor–air mixtures likely to trical equipment and other sources of ignition shall comply be encountered, or result in appreciable shock hazard upon with the requirements of Article 502. Portable electric lu- coming in contact with a grounded object under all normal munaires and other utilization equipment shall not be used operating conditions. The electrostatically charged exposed within a Class II location during operation of the finishing elements of the handgun shall be capable of being ener- processes. Where such luminaires or utilization equipment gized only by an actuator that also controls the coating are used during cleaning or repairing operations, they shall material supply. be of a type identified for Class 11, Division 1 locations,and pp Y all exposed metal parts shall be connected to an equipment (2) Power Equipment. Transformers, power packs, con- grounding conductor. trol apparatus, and all other electrical portions of the equip- Exception: Where portable electric luminaires are required ment shall be located outside of the Class I location or be or operations in spaces not readily illuminated b identified for the location. f I p 1' y fixed lighting within the spraying area, they shall be of the type Exception: The handgun itself card its connections to the listed for Class 11, Division I locations where readily ig- power supply shall be permitted within the Class I location. nitible residues may be present. (3) Handle. The handle of the spraying gun shall be elec- (2) Fixed Electrostatic Spraying Equipment. The provi- trically connected to ground by a metallic connection and sions of 516.10(A) and 516.10(C)(1) shall apply to fixed be constructed so that the operator in normal operating electrostatic spraying equipment. position is in intimate electrical contact with the grounded (3) Electrostatic Hand-Spraying Equipment. The provi- handle to prevent buildup of a static charge on the opera- sions of 516.10(B) and 516.10(C)(1) shall apply to electro- tor's body. Signs indicating the necessity for grounding static hand-spraying equipment. 70-424 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 517—HEALTH CARE FACILITIES 517,2 (4) Electrostatic Fluidized Beds. Electrostatic fluidized I. General beds and associated equipment shall be of identified types. The high-voltage circuits shall be designed such that any dis- 517.1 Scope. The provisions of this article shall apply to charge produced when the charging electrodes of the bed are electrical construction and installation criteria in health care approached or contacted by a grounded object shall not be of facilities that provide services to human beings. sufficient intensity to ignite any powder-air mixture likely to The requirements in Parts II and III not only apply to be encountered or to result in an appreciable shock hazard. single-function buildings but are also intended to be indi- (a) Transformers, power packs, control apparatus, and vidually applied to their respective forms of occupancy all other electrical portions of the equipment shall be lo- within a multifunction building (e.g., a doctor's examining cated outside the powder-coating area or shall otherwise room located within a limited care facility would be re- comply with the requirements of 516.10(C)(1). quired to meet the provisions of 517.10). Exception: The charging electrodes and their connections FPN: For information concerning performance, mainte- to the power supply shall be permitted within the powder- nance, and testing criteria, refer to the appropriate health coating area. care facilities documents. (b) All electrically conductive objects within the 517.2 Definitions. powder-coating area shall be adequately grounded. The powder-coating equipment shall carry a prominent, perma- Alternate Power Source. One or more generator sets, or nently installed warning regarding the necessity for ground- battery systems where permitted,intended to provide power ing these objects. during the interruption of the normal electrical services or the public utility electrical service intended to provide FPN: For more information on grounding and bonding for power during interruption of service normally provided by static electricity purposes, See NFPA 33-2007, Standard for Spiny Application Using Flammable or Combustible Materi- the generating facilities on the premises. als; NFPA 34-2007,Standard for Dipping and Coating Pm- Ambulatory Health Care Occupancy. A building or por- cesses Using Flammable or Combustible Liquids, and NFPA 77-2007,Recommended Practice on Static Electricity. tion thereof used to provide services or treatment simulta- neously to four or more patients that provides, on an out- (c) Objects being coated shall be maintained in electri- patient basis, one or more of the following: cal contact (less than 1 megohm) with the conveyor or (1) Treatment for patients that renders the patients inca- other support in order to ensure proper grounding. Hangers pable of taking action for self-preservation under emer- shall be regularly cleaned to ensure effective electrical con- tact. Areas of electrical contact shall be sharp points or gency conditions without assistance of others. knife edges where possible. (2) Anesthesia that renders the patients incapable of taking (d) The electrical equipment and compressed air sup- action for self-preservation under emergency condi- tions shall be interlocked with a ventilation system so that without the assistance of others. the equipment cannot be operated unless the ventilating (3) Emergency or urgent care for patients who, due to the fans are in operation. [33:Chapter 151 nature of their injury or illness, are incapable of taking action for self-preservation under emergency condi- 516.16 Grounding. All metal raceways, the metal armors tions without the assistance of others. [101:3.3.168.1] or metallic sheath on cables, and all non-current-carrying Anesthetizing Location. Any area of a facility that has metal parts of fixed or portable electrical equipment, re- been designated to be used for the administration of any gardless of voltage,shall be grounded and bonded.Ground- flammable or nonflammable inhalation anesthetic agent in ing and bonding shall comply with 501.30, 502.30, or the course of examination or treatment, including the use of 505.25, as applicable. such agents for relative analgesia. Critical Branch. A subsystem of the emergency system consisting of feeders and branch circuits supplying energy ARTICLE 517 to task illumination, special power circuits, and selected receptacles serving areas and functions related to patient Health Care Facilities care and that are connected to alternate power sources by one or more transfer switches during interruption of normal FPN: Rules that are followed by a reference in brackets power source. [99:3.3.26] contain text that has been extracted from NFPA 99-2005, Electrical Life-Support Equipment. Electrically powered Standard for Health Cure Facilities, and NFPA 101-2006, Life Saferiv Code. Only editorial changes were made to the equipment whose continuous operation is necessary to extracted text to make it consistent with this Code. maintain a patient's life. [99:3.3.37] 2009 Edition NATIONAL ELECTRICAL CODE 70-425 517.2 ARTICLE 517—HEALTH CARE FACILITIES Emergency System. A system of circuits and equipment Hospital. A building or portion thereof used on a 24-hour intended to supply alternate power to a limited number of basis for the medical, psychiatric, obstetrical, or surgical prescribed functions vital to the protection of life and care of four or more inpatients. [101:3.3.124] safety. [99:3.3.41] Isolated Power System. A system comprising an isolating Equipment System. A system of circuits and equipment transformer or its equivalent, a line isolation monitor, and arranged for delayed, automatic, or manual connection to its ungrounded circuit conductors. the alternate power source and that serves primarily Isolation Transformer. A transformer of the multiple- 3-phase power equipment. winding type, with the primary and secondary windings Essential Electrical System. A system comprised of alter- physically separated, which inductively couples its second- nate sources of power and all connected distribution sys- ary winding to the grounded feeder systems that energize terns and ancillary equipment, designed to ensure continu- its primary winding. ity of electrical power to designated areas and functions of Life Safety Branch.A subsystem of the emergency system a health care facility during disruption of normal power consisting of feeders and branch circuits, meeting the re- sources, and also 9: minimize disruption within the internal quirements of Article 700 and intended to provide adequate wiring system. [99:3.3.44] power needs to ensure safety to patients and personnel, and Exposed Conductive Surfaces.Those surfaces that are ca- that are automatically connected to alternate power sources pable of carrying electric current and that are unprotected, during interruption of the normal power source. [99:3.3.96] unenclased, or unguarded, permitting personal contact. Limited Care Facility. A building or portion thereof used Paint, anodizing, and similar coatings are not considered on a 24-hour basis for the housing of four or more persons suitable insulation, unless they are listed for such use. who are incapable of self-preservation because of age; Fault Hazard Current. See Harcu-d Current. physical limitation due to accident or illness; or limitations such as mental retardation/developmental disability, mental Flammable Anesthetics. Gases or vapors, such as flurox- illness, or chemical dependency. [99:3.3.97] ene,cyclopropane, divinyl ether,ethyl chloride, ethyl ether, Line Isolation Monitor.A test instrument designed to con- and ethylene, which may form flammable or explosive mix- tinually check the balanced and unbalanced impedance tures with air, oxygen, or reducing gases such as nitrous from each line of an isolated circuit to ground and equipped oxide. with a built-in test circuit to exercise the alarm without Flammable Anesthetizing Location. Any area of the fa- adding to the leakage current hazard. cility that has been designated to be used for the adminis- Monitor Hazard Current. See Hazard Current. tration of any flammable inhalation anesthetic agents in the normal course of examination or treatment. Nurses' Stations. Areas intended to provide a center of nursing activity for a group of nurses serving bed patients, Hazard Current. For a given set of connections in an where the patient calls are received, nurses are dispatched, isolated power system, the total current that would flow nurses' notes written, inpatient charts prepared, and medi- through a low impedance if it were connected between cations prepared for distribution to patients. Where such either isolated conductor and ground. activities are carried on in more than one location within a Fault Hazard Current. The hazard current of a given iso- nursing unit, all such separate areas are considered a part of lated system with all devices connected except the line the nurses' station. isolation monitor. Nursing Home.A building or portion of a building used on Monitor Hazard Current. The hazard current of the line a 24-hour basis for the housing and nursing care of four or isolation monitor alone. more persons who, because of mental or physical incapac- Total Hazard Current. The hazard current of a given iso- ity, might be unable to provide for their own needs and lated system with all devices, including the line isolation safety without the assistance of another person. monitor, connected. [99:3.3.129] Health Care Facilities. Buildings or portions of buildings Patient Bed Location. The location of a patient sleeping in which medical, dental, psychiatric, nursing, obstetrical, bed, or the bed or procedure table of a critical care area. or surgical care are provided. Health care facilities include, [99:3.3.137] but are not limited to, hospitals, nursing homes, limited Patient Care Area. Any portion of a health care facility care facilities, clinics, medical and dental offices, and am- wherein patients are intended to be examined or treated.Areas bulatory care centers, whether permanent or movable, of a health care facility in which patient care is administered 70-426 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 517—HEALTH CARE FACILITIES 517.11 are classified as general care areas or critical care areas. The Selected Receptacles. A minimum number of electrical governing body of the facility designates these areas in accor- receptacles to accommodate appliances ordinarily re- dance with the type of patient care anticipated and with the quired for local tasks or likely to be used in patient care following definitions of the area classification, emergencies. FPN: Business offices,corridors, lounges,day rooms, din- Task Illumination. Provision for the minimum lighting re- ing rooms, or similar areas typically are not classified as quired to carry out necessary tasks in the described areas, patient care areas. including safe access to supplies and equipment, and access General Care Areas. Patient bedrooms, examining rooms, to exits. treatment rooms, clinics, and similar areas in which it is Therapeutic High-Frequency Diathermy Equipment. intended that the patient will come in contact with ordinary Therapeutic high-frequency diathermy equipment is thera- appliances such as a nurse call system, electric beds, exam- peutic induction and dielectric heating equipment, ining lamps, telephones, and entertainment devices. (99, 2005] Total Hazard Current. See Hazard Current. Critical Care Areas. Those special care units, intensive X-Ray Installations, Long-Time Rating. A rating based care units, coronary care units, angiography laboratories, on an operating interval of 5 minutes or longer, cardiac catheterization laboratories, delivery rooms, operat- X-Ray Installations, Mobile. X-ray equipment mounted ing rooms, and similar areas in which patients are intended on a permanent base with wheels, casters, or a combination to be subjected to invasive procedures and connected to of both to facilitate moving the equipment while com- line-operated, electromedical devices. pletely assembled. Wet Procedure Locations. Those spaces within patient care areas where a procedure is performed and that are X-Ray Installations, Momentary Rating. A rating based normally subject to wet conditions while patients are on an operating interval that does not exceed 5 seconds. present. These include standing fluids on the floor or X-Ray Installations, Portable. X-ray equipment designed drenching of the work area, either of which condition is to be hand carried. intimate to the patient or staff. Routine housekeeping pro- cedures and incidental spillage of liquids do not define a X-Ray Installations, Transportable. X-ray equipment to wet location. be installed in a vehicle or that may be readily disas- sembled for transport in a vehicle. Patient Care Vicinity. In an area in which patients are normally cared for, the patient care vicinity is the space with surfaces likely to be contacted by the patient or an atten- dant who can touch the patient. Typically in a patient room, 517.10 Applicability. this encloses a space within the room not less than 1.8 m(6 ft) beyond the perimeter of the bed in its nominal location, and (A) Applicability. Part 11 shall apply to patient care areas extending vertically not less than 2.3 m (7%2 ft) above the of all health care facilities. floor. [99:3.3.1401 (B) Not Covered. Part If shall not apply to the following: Patient Equipment Grounding Point. A jack or terminal (1) Business offices, corridors, waiting rooms, and the like that serves as the collection point for redundant grounding in clinics, medical and dental offices, and outpatient of electrical appliances serving a patient care vicinity or for facilities grounding other items in order to eliminate electromagnetic (2) Areas of nursing homes and limited care facilities interference problems. (99:3.3.141] wired in accordance with Chapters 1 through 4 of this Psychiatric Hospital. A building used exclusively for the Code where these areas are used exclusively as patient psychiatric care, on a 24-hour basis, of four or more sleeping rooms inpatients. FPN: See NFPA 101`-2006,Life Safety Cade®. Reference Grounding Point, The ground bus of the pan- 517.11 General Installation — Construction Criteria. elboard or isolated power system panel supplying the pa- The purpose of this article is to specify the installation tient care area. criteria and wiring methods that minimize electrical haz- Relative Analgesia.A state of sedation and partial block of ards by the maintenance of adequately low potential differ- pain perception produced in a patient by the inhalation of ences only between exposed conductive surfaces that are concentrations of nitrous oxide insufficient to produce loss likely to become energized and could be contacted by a of consciousness (conscious sedation). patient. 2008 Edition NATIONAL ELECTRICAL CODE 70-427 517.12 ARTICLE 517—HEALTH CARE FACILITIES FPN: In a health care facility, it is difficult to prevent the Care vicinity shall be permitted to be connected to an occurrence of a conductive or capacitive path from the pa- equipment grounding return path complying with tient's body to some grounded object, because that path S17.13(A). may be established accidentally or through instrumentation directly connected to the patient. Other electrically conduc- tive surfaces that may make an additional contact with the 517.14 Panelboard Bonding. The equipment grounding patient,or instruments that may be connected to the patient, terminal buses of the normal and essential branch-circuit then become possible sources of electric currents that can panelboards serving the same individual patient Care vicin- traverse the patient's body.The hazard is increased as more ity shall be connected together with an insulated continuous apparatus is associated with the patient, and, therefore, capper conductor not smaller than 10 AWG. Where two or more intensive precautions are needed. Control of electric shock hazard requires the limitation of electric current that more panelboards serving the same individual patient care might How in an electrical circuit involving the patient's vicinity are served from separate transfer switches on the body by raising the resistance of the conductive circuit that emergency system, the equipment grounding terminal includes the patient, or by insulating exposed surfaces that buses of those panelboards shall be connected together with might become energized, in addition to reducing the poten- an insulated continuous copper conductor not smaller than tial difference that can appear between exposed conductive surfaces in the patient care vicinity, or by combinations of 10 AWG.This conductor shall be permitted to be broken in these methods. A special problem is presented by the pa- order to terminate on the equipment grounding terminal bus tient with an externalized direct conductive path to the in each panelboard. heart muscle. The patient may he electrocuted at current levels so low that additional protection in the design of 517.16 Receptacles with Insulated Grounding Termi- appliances, insulation of the catheter, and control of medi- cal practice is required. oats. Receptacles with insulated grounding terminals, as permitted in 250.146(D), shall be identified, such identifi- 517.12 Wiring Methods. Except as modified in this ar- cation shall be visible after installation. ticle, wiring methods shall comply with the applicable re- FPN: Caution is important in specifying such a system quirements of Chapters I through 4 of this Code. with receptacles having insulated grounding terminals, since the grounding impedance is controlled only by the 517.13 Grounding of Receptacles and Fixed Electrical equipment grounding conductors and does not benefit func- ionally from any parallel grounding paths. This type or t Equipment in Patient Care Areas. Wiring in patient care installation is typically used where a reduction of electrical areas shall comply with 517,13(A) and (B). noise(electromagnetic in(erference) is necessary and paral- (A) Wiring Methods. All branch circuits serving patient lel grounding paths are to be avoided. care areas shall be provided with an effective ground-fault 517.17 Ground-Fault Protection. current path by installation in a metal raceway system, or a cable having a metallic armor or sheath assembly. The (A) Applicability. The requirements of 5I7.17 shall apply metal raceway system, or metallic cable armor, or sheath to hospitals and other buildings (including multiple- occupancy buildings) with critical care areas or utilising conductor in accordance with 250.118. electrical life support equipment, and buildings that provide the required essential utilities or services for the operation (B) Insulated Equipment Grounding Conductor. The of critical care areas or electrical life support equipment. grounding terminals of all receptacles and all non–current- carrying conductive surfaces of fixed electrical equipment (B) Feeders. Where ground-fault protection is provided likely to become energized that are subject to personal con- for operation of the service disconnecting means or feeder tact, operating at over 100 volts, shall be connected t0 an disconnecting means as specified by 230.45 or 215.1Q, an insulated copper equipment grounding conductor. The additional step of ground-fault protection shall be provided in all next level feeder disconnecting means downstream equipment grounding conductor shall be sized in accor- dance with Table 250.122 and installed in metal raceways toward the load. Such protection shall consist of overcur- or as a part of listed cables having a metallic armor or rent devices and current transformers or other equivalent sheath assembly with the branch-circuit conductors supply- protective equipment that shall cause the feeder disconnect- ing means to open. ing these receptacles or fixed equipment. The additional levels of ground-fault protection shall Exception No. 1: Metal faceplates shall be permuted to be not be installed as follows: connected to the equipment grounding conductor by means (l) On the load side of an essential electrical system trans- of a metal mounting screiv(s) securing the faceplate to a fer switch grounded outlet box or grounded wiring device. (2) Between the on-site generating unit(s) described in Exception No. 2: Luminaires more that 2.3 in (7'fz ft) 517.35(B) and the essential electrical system transfer above the poor and snitches located outside of the patient switch(es) 70-428 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 517—HEALTH CARE FACILITIES 517.19 (3) On electrical systems that are not solidly grounded wye Exception No. 2: Psychiatric security rooms shall not be systems with greater than 150 volts to ground but not required to have receptacle outlets installed in the room. exceeding 600 volts phase-to-phase FPN: Ik is not intended that there be a total, immediate replacement of existing non--hospital grade receptacles.It is (C) Selectivity. Ground-fault protection for operation of intended, however, that non-hospital grade receptacles be the service and feeder disconnecting means shall be fully replaced with hospital grade receptacles upon modification selective such that the feeder device, but not the service of use, renovation, or as existing receptacles need device, shall open on ground faults on the load side of the replacement. feeder device.A six-cycle minimum separation between the service and feeder ground-fault tripping bands shall be pro- (C) Pediatric Locations. Receptacles located within the vided. Operating time of the disconnecting devices shall be rooms, bathrooms, playrooms, activity rooms, and patient considered in selecting the time spread between these two care areas of pediatric wards shall be listed tamper resistant or shall employ a listed tamper resistant cover. bands to achieve 100 percent selectivity. FPN: See 230.95, fine print note, for transfer of alternate 517.19 Critical Care Areas. source where ground-fault protection is applied. (A) Patient Bed Location Branch Circuits. Each patient (D) Testing. When equipment ground-fault protection is bed location shall be supplied by at least two branch cir- first installed, each level shall be performance tested to cuits, one or more from the emergency system and one or ensure compliance with 517.17(0). more circuits from the normal system. At least one branch circuit from the emergency system shall supply an outlet(s) 517.18 General Care Areas. only at that bed location. All branch circuits from the nor- mal system shall be from a single panelboard. Emergency (A) Patient Bed Location. Each patient bed location shall system receptacles shall be identified and shall also indicate be supplied by at least two branch circuits, one from the the panelboard and circuit number supplying them. emergency system and one from the normal system. All branch circuits from the normal system shall originate in Exception No. 1: Branch circuits serving only special- the same panelboard. purpose receptacles or equipment in critical care areas shall be permitted to be served by other panelboards. Exception No, 1: Branch circuits serving only special- Exception No. 2: Critical care locations served from two purpose outlets or receptacles, such as portable X-ray out- separate transfer switches on the emergence system shall lets, shall not be required to be served from the same dis- not be required to have circuits from the normal system. tribution panel or panels. Exception No. 2: Requirements of 517.18(A) shall not ap- (B) Patient Bed Location Receptacles. ply to patient bed locations in clinics, medical and dental (1) Minimtun Number and Supply. Each patient bed to- offices, and outpatient facilities; psychiatric, substance cation shall be provided with a minimum of six receptacles, abuse, and rehabilitation hospitals; sleeping rooms of nurs- at least one of which shall be connected to either of the ing homes and limited cure facilities meeting the require- following: meats of 517.10(B)(2). (1) The normal system branch circuit required in Exception No. 3: A general care patient bed location 517.19(A) served front two separate transfer switches on the emer- (2) An emergency system branch circuit supplied by a dif- gency system shall not be required to have circuits from the ferent transfer switch than the other receptacles at the normal system. same location (B) Patient Bed Location Receptacles. Each patient bed (2) Receptacle Requirements.The receptacles required in location shall be provided with a minimum of four recep- 517.19(B)(1) shall be permitted to be of the single or du- tacles.They shall be permitted to be of the single or duplex plex types or a combination of both. All receptacles, types or a combination of both. All receptacles, whether whether six or more, shall be listed "hospital grade" and so four or more, shall be listed "hospital grade" and so iden- identified. The grounding terminal of each receptacle shall tified. The grounding terminal of each receptacle shall be be connected to the reference grounding point by means of connected to an insulated copper equipment grounding con- an insulated copper equipment grounding conductor. ductor sized in accordance with Table 250.122. {C} Patient Care Vicinity Grounding and Bonding Exception No. 1: The requirements of 517.18(B) shall not (Optional).A patient care vicinity shall be permitted to have apply to psychiatric, substance abuse, and rehabilitation a patient equipment grounding point. The patient equipment hospitals meeting the requirements of 517 10(B)(2). grounding point,where supplied, shall be permitted to contain 2008 Edition NATIONAL ELECTRICAL CODE 70-429 517.20 ARTICLE 517—HEALTH CARE FACILITIES one or more listed grounding and bonding jacks. An equip- tacles. Where such a circuit is served from an isolated un- ment bonding jumper not smaller than 10 AWG shall be used grounded system, the grounding conductor shall not be to connect the grounding terminal of all grounding-type recep- required to be run with the power conductors; however, the tacles to the patient equipment grounding point. The bonding equipment grounding terminal of the special-purpose recep- conductor shall be permitted to be arranged centrically or tacle shall be connected to the reference grounding point. looped as convenient. 517.20 Wet Procedure Locations. FPN: Where there is no patient equipment grounding point,it is important that the distance between the reference (A) Receptacles and Fixed Equipment. All receptacles grounding point and the patient care vicinity be as short as and fixed equipment within the area of the wet procedure possible to minimize any potential differences. location shall have ground-fault circuit-interrupter protec- (D) Panelboard Grounding and Bonding. Where a tion for personnel if interruption of power under fault con- grounded electrical distribution system is used and metal ditions can be tolerated, or be served by an isolated power feeder raceway or Type MC or MI cable that qualifies as an system if such interruption cannot be tolerated. equipment grounding conductor in accordance with Exception: Branch circuits supplying only listed, feed. 250.11$ is installed, grounding of a panelboard or switch- therapeutic and diagnostic equipment shall he permitted to board shall be ensured by one of the following bonding be supplied front a grounded sender, single- or 3-phase means at each termination or junction point of the metal sYstem, provided that raceway or Type MC or MI cable: (a) Wiring for grounded and isolated circuits does not (1) A grounding bushing and a continuous copper bonding occupy the same raceway, and jumper, sized in accordance with 250.122, with the (b) All conductive surfaces of the equipment are con- bonding jumper connected to the junction enclosure or nected to an equipment grounding conductor the ground bus of the panel (2) Connection of feeder raceways or Type MC or MI (B) Isolated Power Systems. Where an isolated power cable to threaded hubs or bosses on terminating enclo- system is utilized, the isolated power equipment shall be listed as isolated power equipment, and the isolated power cures system shall be designed and installed in accordance with {3) Other approved devices such as bonding-type locknuts 517.160. or bushings FPN: For requirements for installation of therapeutic pools (E) Additional Protective Techniques in Critical Care and tubs, see Part VI of Article 680. Areas (Optional). Isolated power systems shall be permit- ted to be used for critical care areas, and, if used, the iso- 517.21 Ground-Fault Circuit-Interrupter Protection for lated power system equipment shall be listed as isolated Personnel. Ground-fault circuit-interrupter protection for power equipment. The isolated power system shall be de- personnel shall not be required for receptacles installed in signed and installed in accordance with 517.160. those critical care areas where the toilet and basin are in- stalled within the patient room. Exception: The audible and visual indicators of the line isolation monitor .shall be permitted to be located at the nursing station for the area tieing served. III. Essential Electrical System 517.25 Scope. The essential electrical system for these fa- (F) Isolated Power System Grounding. Where an iso- cilities shall comprise a system capable of supplying a lim- fault current to a low magnitude, the grounding conductor lated ungrounded power source is used and limits the first- ited amount of lighting and power service, which is consid- associated with the secondary circuit shall be permitted to ered essential For life safety and orderly cessation of be run outside of the enclosure of the power conductors in procedures during the time normal electrical service is in- terrupted for any reason. This includes clinics, medical and the same circuit. dental offices, outpatient facilities, nursing homes, limited FPN: Although it is permitted to run the grounding con- care facilities, hospitals, and other health care facilities ductor outside of the conduit, it is safer to run it with the power conductors to provide better protection in case of a serving patients. second ground fault. FPN: For information on the need for an essential electri- cal system, see NFPA 99-2005, Standard for Health Care(G) Special-Purpose Receptacle Grounding. The equip- Facilities. ment grounding conductor for special-purpose receptacles, such as the operation of mobile X-ray equipment, shall be 517.26 Application of Other Articles, The essential elec- extended to the reference grounding points of branch cir- trical system shall meet the requirements of Article 700, cuits for all locations likely to be served from such recep- except as amended by Article 517. 701430 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 517--HEALTH CARE FACILITIES 517.30 517.30 Essential Electrical Systems for Hospitals. Normal Alternate power source source (A) Applicability. The requirements of Part III, 517.30 through 517.35, shall apply to hospitals where an essential Normal electrical system is required. system FPN No. l: For performance, maintenance, and testing T requirements of essential electrical systems in hospitals,see NFPA 99-2005, Standard for Health Care Facilities. For Nonessential ° installation of centrifugal fire pumps, see NFPA 20-2007, loads Standard for the Installation of Stationary Fire Pumps for Automatic Fire Protection. `1` switching equipment Equipment Life safety Critical FPN No. 2: For additional information, see NFPA 99- sste branch branch 2005, Standard for Health Care Facilities. Delayed t automatic Emergency system (B) General. switching equipment (1) Separate Systems.Essential electrical systems for hos- Essential electrical system pitals shall be comprised of two separate systems capable FPN Figure 517.30,No. I Hospital—Minimum Requirement of supplying a limited amount of lighting and power ser- for Transfer Switeb Arrangement. vice that is considered essential for life safety and effective hospital operation during the time the normal electrical ser- Normal power vice is interrupted for an reason. These two stems shall source Alternate power P Y Y source be the emergency system and the equipment system. (2) Emergency Systems. The emergency system shall be Normal supply limited to circuits essential to life safety and critical patient care. These are designated the life safety branch and the critical branch. [99:4.4.2.2.1.1] Nonessential o loads (3) Equipment System. The equipment system shall sup- ply major electrical equipment necessary for patient care Automalic and basic hospital operation. switching equipment (4) Transfer Switches.The number of transfer switches to be used shall be based on reliability, design, and load con- Equipment Life safety siderations. Each branch of the emergency system and each system branch Critical equipment system shall have one or more transfer switches. branch One transfer switch shall be permitted to serve one or more Essential electrical system branches or systems in a facility with a maximum demand on the essential electrical system of 150 kVA. FPN Figure 517.30,No.2 Hospital—Minimum Requirement (150 kVA or less) for Transfer Switch Arrangement. FPN No. 1: See NFPA 99-2005,Standard for Health Care Facilities: 4.4.3.2, Transfer Switch Operation Type I; (6) Contiguous Facilities. Hospital power sources and al- 4.4.2.1.4, Automatic Transfer Switch Features; and ternate power sources shall be permitted to serve the essen- 4.4.2.1.6. Nonautomatic Transfer Device Features. tial electrical systems of contiguous or same site facilities. FPN No. 2: See FPN Figure 517.30, No. 1. [99:13.3.4.3] FPN No. 3: See FPN Figure 517.30, No. 2. (C) Wiring Requirements. (1) Separation from Other Circuits. The life safety (5) Optional Loads. Loads served by the generating branch and critical branch of the emergency system shall be equipment not specifically named in Article 517 shall be kept entirely independent of all other wiring and equipment served by their own transfer switches such that the follow- and shall not enter the same raceways, boxes, or cabinets ing conditions apply: with each other or other wiring. (1) These loads shall not be transferred if the transfer will Wiring of the life safety branch and the critical branch overload the generating equipment. shall be permitted to occupy the same raceways, boxes, or (2) These loads shall be automatically shed upon generat- cabinets of other circuits not part of the branch where such ing equipment overloading. wiring complies with one of the following: 2008 Edition NATIONAL ELECTRICAL CODE 70-431 517.31 ARTICLE 517—HEALTH CARE FACILITIES (1) Is in transfer equipment enclosures and proper rating to meet the demand produced by the load (2) Is in exit or emergency luminaires supplied from two of the essential electrical system(s) at any given time. sources Demand calculations for sizing of the generator set(s) (3) Is in a common junction box attached to exit or emer- shall be based on any of the following: gency luminaires supplied from two sources (1) Prudent demand factors and historical data (4) Is for two or more emergency circuits supplied from (2) Connected load the same branch (3) Feeder calculation procedures described in Article 220 The wiring of the equipment system shall be permitted (4) Any combination of the above to occupy the same raceways, boxes, or cabinets of other The sizing requirements in 700.5 and 701.6 shall not circuits that are not part of the emergency system, apply to hospital generator set(s). (2) Isolated Power Systems. Where isolated power sys- (E) Receptacle Identification. The cover plates for the tems are installed in any of the areas in 517.33(A)(1) and electrical receptacles or the electrical receptacles them- (A)(2), each system shall be supplied by an individual cir- selves supplied from the emergency system shall have a cuit serving no other load. distinctive color or marking so as to be readily identifiable. (3) Mechanical Protection of the Emergency System. [99:4.4.2.2.4.2(B)] The wiring of the emergency system in hospitals shall be mechanically protected. Where installed as branch circuits $17.31 Emergency System. Those functions of patient in patient care areas, the installation shall comply with the care depending on lighting or appliances that are connected requirements of 517.13(A) and (B). The following wiring to the emergency system shall be divided into two manda- methods shall be permitted: tory branches: the life safety branch and the critical branch, described in 517.32 and 517.33. ([) Nonflexible metal raceways, Type MI cable, or 5ched- The branches of the emergency system shall be m- ule SO PVC conduit. Nonmetallic raceways shall not be stalled and connected to the alternate power source so that used for branch circuits that supply patient care areas. all functions specified herein for the emergency system shall (2) Where encased in not less than 50 mm (2 in.) of con- be automatically restored to operation within 10 seconds after crete, Schedule 40 PVC conduit, flexible nonmetallic interruption of the normal source. [99:4.4.2.2.2.1,4.4.3.11 or jacketed metallic raceways, or jacketed metallic cable assemblies listed for installation in concrete. 517.32 Life Safety Branch. No function other than those Nonmetallic raceways shall not be used for branch cir- listed in 517.32(A) through (H) shall be connected to the cuits that supply patient care areas. life safety branch, The life safety branch of the emergency (3) Listed flexible metal raceways and listed metal system shall supply power for the following lighting,recep- sheathed cable assemblies in any of the following: tacles, and equipment. a. Where used in listed prefabricated medical head- (A) Illumination of Means of Egress. Illumination of walls means of egress, such as lighting required for corridors, b. In listed office furnishings passageways, stairways, and landings at exit doors, and all c. Where fished into existing walls or ceilings, not other- necessary ways of approach to exits. Switching arrange- wise accessible and not subject to physical damage menns to transfer patient corridor lighting in hospitals from d. Where necessary for flexible connection to general illumination circuits to night illumination circuits equipment shall be permitted, provided only one of two circuits can be (4) Flexible power cords of appliances or other utilization selected and both circuits cannot be extinguished at the equipment connected to the emergency system. same time. (5) Secondary circuits of Class 2 or Class 3 communica- FPN: See NFPA 101-2006, Life Safety Cade, Sections 7.8 tion or signaling systems with or without raceways. and 7.9. FPN: See 517.13 for additional grounding requirements in patient care areas. (B) Exit Signs. Exit signs and exit directional signs. FPN: See NFPA 101-2006,Life Safety Code,Section 7.10. (D) Capacity of Systems. The essential electrical system shall have adequate capacity to meet the demand for the (C) Alarm and Alerting Systems. Alarm and alerting sys- operation of all functions and equipment to be served by tems including the following: each system and branch. (]} Fire alarms Feeders shall be sized in accordance with Articles 215 FPN: See NFPA 101-2006, Life Safem Code, Section 9.6 and 220. The generator set(s) shall have sufficient capacity and 18.3.4. 70--432 NATIONAL ELECTRICAL CODE 2009 Edition ARTICLE 517—HEALTH CARE FACILITIES 517.34 (2) Alarms required for systems used for the piping of a. General care beds (at least one duplex receptacle nonflammable medical gases per patient bedroom) FPN: See NFPA 99-2005,Standard fin-Health Cara Facili_ b. Angiographic labs ties, 4.4.2.2.2 20). c. Cardiac catheterization labs (3) Mechanical, control, and other accessories required for d. Coronary care units effective life safety systems operation shall be permit- e. Hemodialysis rooms or areas ted to be connected to the Iife safety branch. f. Emergency room treatment areas (selected) g. Human physiology labs (D) Communications Systems. Hospital communications h. Intensive care units systems, where used for issuing instructions during emer- i. Postoperative recovery rooms (selected) gency conditions. (9) Additional task illumination, receptacles, and selected power circuits needed for effective hospital operation. (E) Generator Set and Transfer Switch Locations. Task Single-phase fractional horsepower motors shall be illumination battery charger for battery-powered lighting permitted to be connected to the critical branch. unit(s) and selected receptacles at the generator set and [99.4.4.2.2.2.3(9)] essential transfer switch locations. [99:4.4.2.2.2.2(5)] (B) Subdivision of the Critical Branch. It shall be per- (F) Generator Set Accessories. Generator set accessories mitted to subdivide the critical branch into two or more as required for generator performance. branches. (G) Elevators. Elevator cab lighting, control, communica- FPN: It is important to analyze the consequences of sup- tions, and signal systems. plying an area with only critical care branch power when failure occurs between the area and the transfer switch. (H) Automatic Doors. Automatically operated doors used Some proportion of normal and critical power or critical for building egress. [99:4.4.2.2.2.2(7)] power from separate transfer switches may be appropriate. 517.33 Critical Branch. 517.34 Equipment System Connection to Alternate Power Source. The equipment system shall be installed (A) Task Illumination and Selected Receptacles. The and connected to the alternate power source such that the critical branch of the emergency system shall supply power equipment described in 517.34(A) is automatically restored for task illumination, fixed equipment, selected receptacles, to operation at appropriate time-iag intervals following the and special power circuits serving the following areas and energizing of the emergency system. Its arrangement shall functions related to patient care: also provide for the subsequent connection of equipment (1) Critical care areas that utilize anesthetizing gases — described in 517.34(B). [99:4.4.2.2.3.2] task illumination, selected receptacles, and fixed equip- E.rceptintt: For essential electrical srstetrrs under 150 kUA, ment deletion of the time-lair intervals ftature for Bela}•ed auto- (2) The isolated power systems in special environments auto- matic connection to the equipment system shall be (3) Patient care areas — task illumination and selected re- permitted. ceptacles in the following: a. Infant nurseries (A) Equipment for Delayed Automatic Connection.The b. Medication preparation areas following equipment shall be permitted to be arranged for c. Pharmacy dispensing areas delayed automatic connection to the alternate power d. Selected acute nursing areas source: e. Psychiatric bed areas (omit receptacles) (1) Central suction systems serving medical and surgical f. Ward treatment rooms functions, including controls. Such suction systems g. Nurses' stations (unless adequately lighted by corri- shall be permitted on the critical branch. dor luminaires) (4) Additional specialized patient care task illumination {2) Sump pumps and other equipment required to operate for the safety of major apparatus, including associated and receptacles, where needed control systems and alarms. (5) Nurse call systems (3) Compressed air systems serving medical and surgical (6) Blood, bone, and tissue banks functions, including controls. Such air systems shall be (7) Telephone equipment rooms and closets permitted on the critical branch. (8) Task illumination, selected receptacles, and selected (4) Smoke control and stair pressurization systems, or power circuits for the following: both. 2008 Edition NATIONAL ELECTRICAL CODE 70-433 517.35 ARTICLE 517—HEALTH CARE FACILITIES (5) Kitchen hood supply or exhaust systems, or both, if (3) Hyperbaric facilities. required to operate during a fire in or under the hood. (4) Hypobaric facilities. (6) Supply, return, and exhaust ventilating systems for air- (5) Automatically operated doors borne infectious/isolation rooms, protective environment rooms, exhaust fans for laboratory fume hoods, nuclear (6) Minimal electrically heated autoclaving equipment shall be permitted to be arranged for either automatic medicine areas where radioactive material is used, ethyl- or manual connection to the alternate source, ene oxide evacuation, and anesthesia evacuation. Where (7) Controls for equipment listed in 517.34. delayed automatic connection is not appropriate, such ventilation systems shall be permitted to be placed on the (g) Other selected equipment shall be permitted to be critical branch. [994.4.2.2.3.4(1)through (6)] served by the equipment system. [99:4.4.2.2.3.5(9)] (7) Supply,return, and exhaust ventilating systems for op- (C) AC Equipment for Nondelayed Automatic Connec- erating and delivery rooms. tion. Generator accessories, including but not limited to, Exception: Sequential delayed automatic connection to the the transfer fuel pump, electrically operated louvers, and alternate power source to prevent overloading the genera- other generator accessories essential for generator opera- tor shall be permitted where engineering studies indicate it Lion, shall be arranged for automatic connection to the al- is necessary. ternate power source. [99:4.4.2.2.3.31 (B) Equipment for Delayed Automatic or Manual Con- 517.35 Sources of Power. nection. The following equipment shall be permitted to be (A) Two Independent Sources of Power. Essential elec- arranged for either delayed automatic or manual connection trical systems shall have a minimum of two independent to the alternate power source: sources of power: a normal source generally supplying the (1) Heating equipment to provide heating for operating, entire electrical system and one or more alternate sources for delivery, labor, recovery, intensive care, coronary care, use when the normal source is interrupted. [99.4.4.1.1.41 nurseries, infection/isolation rooms, emergency treat- ment spaces, and general patient rooms and pressure (B) Alternate Source of Power. The alternate source of maintenance (jockey or make-up) pump(s) for water- power shall be one of the following: based fire protection systems. (1) Generator(s) driven by some form of prime mover(s) and located on the premises Exception; Heating of general patient roams and (2) Another generating unit(s) where the normal source infection/isolation rooms during disruption of the normal consists of a generating unit(s) located on the premises source shall not be required under any of the following conditions: (3) An external utility service when the normal source con- sists of a generating unit(s) located on the premises (I) The outside design temperature is higher than (4) A battery system located on the premises [99:4.4.1.21 (2) The outside design temperature is lower than (C) Location of Essential Electrical System Compo- -6.7°C (20°F), and where a selected room(s) is provided nents. Careful consideration shall be given to the Iocation for the needs of all confined patients, only such room(s) of the spaces housing the components of the essential elec- need be heated. trical system to minimize interruptions caused by natural (3) The facility is served by a dual source of normal forces common to the area (e.g., storms, floods, earth- power quakes, or hazards created by adjoining structures or activi- ties). Consideration shall also be given to the possible in- FPN No, l: The design temperature is based on the 97112 terruption of normal electrical services resulting from percent design value as shown in Chapter 24 of the similar causes as well as possible disruption of normal elec- ASHRAE Handbook of Fundamentals(1997). trical service due to internal wiring and equipment failures. FPN No. 2: For a description of a dual source of normal power, see 517.35(C), FPN. FPN: Facilities in which the normal source of power is supplied by two or more separate central station-fed ser- (2) An elevator(5) selected Co provide service to patient, vices experience greater than normal electrical service reli- surgical, obstetrical, and ground floors during interrup- ability than those with only a single feed. Such a dual tion of normal power. In instances where interruption source of normal power consists of two or more electrical of normal power would result in other elevators stop- services fed from separate generator sets or a utility distri- ping between floors, throw-over facilities shall be pro- bution network that has multiple power input sources and is arranged to provide mechanical and electrical separation so vided to allow the temporary operation of any elevator that a fault between the facility and the generating sources for the release of patients or other persons who may be is not likely to cause an interruption of more than one of the confined between floors. facility service feeders. 70--434 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 517—HEALTH CARE FACILITIES 517.41 517.40 Essential Electrical Systems for Nursing Homes (B) Transfer Switches.The number of transfer switches to and Limited Care Facilities. be used shall be based on reliability, design, and load con- siderations. Each branch of the essential electrical system (A) Applicability. The requirements of Part III, 517.40(C) shall be served by one or more transfer switches.One trans- through 517.44, shall apply to nursing homes and limited fer switch shall be permitted to serve one or more branches care facilities. or systems in a facility with a maximum demand on the Exception: The requirements of Part III. 517.40(C) essential electrical system of 150 kVA. [99:4.5.2.2.1] through 51744, shall riot apply to freestanding buildings FPN No. 1: See NFPA 99-2005,Standard far Health Care used as nursing homes and limited care facilities, provided Facilities, 4.5.3.2. Transfer Switch Operation Type 11; that the following apply: 4.4 2.1.4, Automatic Transfer Switch Features: and (a) Admitting and discharge policies are maintained 4.4.2.1.6, Nonautomatic Transfer Device Features, that preclude the provision of care for any patient or resi- FPN No. 2: See FPN Figure 517.4 1, No. I. miry dent who y need to be sustainer( by electrical life- FPN No. 3: See FPN Figure 517.41, No, 2. support equipment. (b) No surgical meatment requiring general anesthesia Normal power Alternate power is offered. source source (c) An autornatic• battery-operated systeni(s) or equip- ment is provided that shrill be effective for at least I1/: Normal hours and is otherwise in accordance with 700.12 and that system shrill be capable of.supph•ing lighting for exit lights, exit corridors, stairivays, nursing .stations, medical preparation areas, boiler roosts, and communications areas. This sys- Nonessential ° • loads tern shall also supply power to operate all alarm systems. 199:17.3.4.2.2(3), 18.3.4.2.2(3)1 Automatic 1 switching equipment Lile salely FPN: See NFPA 101-2006, Life Safety Code. branch Delayed Critical n atient Hospital Care Facilities. For those nursing automatic branch (B} I p p g switching homes and limited care facilities that admit patients who equipment Essential electrical system need to be sustained by electrical life support equipment, the essential electrical system from the source to the portion of the FPN Figure 517.41,No. 1 Nursing Home and Limited Health facility where such patients are treated shall comply with the Care Facilities—Minimum Requirement for Transfer Switch requirements of Part III, 517.30 through 517.35. Arrangement. (C) Facilities Contiguous or Located on the Same Site Normal power Alternate power with Hospitals. Nursing homes and limited care facilities source source that are contiguous or located on the same site with a hos- pital shall be permitted to have their essential electrical Normal systems supplied by that of the hospital. system ' FPN: For performance, maintenance, and testing require- ments of essential electrical systems in nursing homes and ° limited care facilities, see NFPA 99-2005, Standard for Nonessential Health Care Facilities. loads 517.41 Essential Electrical Systems. .,. Automatic ❑ switching (A) General. Essential electrical systems for nursing homes equipment and limited care facilities shall be comprised of two separate Critical branch branches capable of supplying a limited amount of lighting Life safety and power service, which is considered essential for the pro- branch tection of life safety and effective operation of the institution Essential electrical system during the time normal electrical service is interrupted for any FPN Figure 517.41,No. 2 Nursing Home and Limited Health reason. These two separate branches shall be the life safety Care Facilities — Minimum Requirement (150 kVA or less) branch and the critical branch. [99: A.4.5.2.2.t] for Transfer Switch Arrangement. 2008 Edition NATIONAL ELECTRICAL,CODE 70-435 517.42 ARTICLE 517---HEALTH CARE FACILITIES (C) Capacity of System. The essential electrical system FPN: See NFPA 101-2006, Life Safety Code, Sections 9.6 shall have adequate capacity to meet the demand for the and 18.3.4. operation of all functions and equipment to be served by (2) Alarms required for systems used for the piping of each branch at one time. nonflammable medical gases FPN: See NFPA 99-2005,Standard for Health Care Facili- (D) Separation from Other Circuits. The life safety ties,4.4.2.2.2.2(3). branch shall be kept entirely independent of all other wiring and equipment and shall not enter the same raceways, (D) Communications Systems. Communications systems, boxes, or cabinets with other wiring except as follows: where used for issuing instructions during emergency con- (1) In transfer switches ditions. (2) In exit or emergency luminaires supplied from two (E) Dining and Recreation Areas. Sufficient lighting in sources (3) In a common junction box attached to exit or emer- dining and recreation areas to provide illumination to exit gency luminaires supplied from two sources ways. The wiring of the critical branch shall be permitted to (E) Generator Set Location. Task illumination and re- occupy the same raceways, boxes, or cabinets of other cir- lected receptacles in the generator set location. cuits that are not part of the life safety branch. (G) Elevators. Elevator cab lighting, control, communica- (E) Receptacle Identification. The cover plates for the tions, and signal systems. [99:4.4.2.2.2.2(6), 4.5.2.2.2(7)] electrical receptacles or the electrical receptacles them- selves supplied from the emergency system shall have a 517.43 Connection to Critical Branch.The critical branch distinctive color or marking so as to be readily identifiable. shall be installed and connected to the alternate power source [99:4.5.2.2.4.2] so that the equipment listed in 517.43(A) shall be automati- cally restored to operation at appropriate time-lag intervals 517.42 Automatic Connection to Life Safety Branch. following the restoration of the life safety branch to operation. The life safety branch shall be installed and connected to Its arrangement shall also provide for the additional connec- the alternate source of power so that all functions specified tion of equipment listed in 517.43(B) by either delayed auto- herein shall be automatically restored to operation within matic or manual operation. [99:4,5.2.13.1] 10 seconds after the interruption of the normal source. No Exception: For essential electrical systems under 150 kVA, functions other than those listed in 517.42(A) through (G) deletion of the time-lag intervals feature for delayed auto shall be connected to the life safety branch. The life safety matic connection to the equipment system shall be branch shall supply power for the following lighting, recep- permitted tacles, and equipment. FPN: The life safety branch is called the emergency sys- (A) Delayed Automatic Connection. The following tem in NFPA 99-2005,Standard for Health Care Facilities. equipment shall be perm,itted to be connected to the critical branch and shall be arranged for delayed automatic connec- (A) Illumination of Means of Egress. Illumination of lion to the alternate power source: means of egress as is necessary for corridors, passageways, stairways, landings, and exit doors and all ways of ap- (1) Patient care areas— task illumination and selected re- proach to exits. Switching arrangement to transfer patient ceptacles in the following: corridor lighting from general illumination circuits shall be a. Medication preparation areas permitted, providing only one of two circuits can be se- b. Pharmacy dispensing areas lected and both circuits cannot be extinguished at the same c. Nurses'stations (unless adequately lighted by corri- time. dor luminaires) FPN: See NFPA 101-2006, Life Safety Code, Sections 7.8 (2) Sump pumps and other equipment required to operate and 7.9. for the safety of major apparatus and associated control systems and alarms (B) Exit Signs. Exit signs and exit directional signs. (3) Smoke control and stair pressurization systems FPN: See NFPA 101-2006,Life Safety Code, Section 7.10. (4) Kitchen hood supply and/or exhaust systems, if re- quired to operate during a tire in or under the hood (C) Alarm and Alerting Systems. Alarm and alerting sys- (5) Supply, return, and exhaust ventilating systems for air- tems, including the following: borne infectious isolation rooms [99:4.5.2,2.3.3(1) (1) Fire alarms through (5)] 70-436 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 517—HEALTH CARE FACILITIES 5I7.60 (B) Delayed Automatic or Manual Connection. The fol- of the spaces housing the components of the essential elec- lowing equipment shall be permitted to be connected to the trical system to minimize interruptions caused by natural critical branch and shall be arranged for either delayed au- forces common to the area (e.g., storms, floods, earth- tomatic or manual connection to the alternate power source: quakes, or hazards created by adjoining structures or activi- (I) Heating equipment to provide heating for patient ties). Consideration shall also be given to the possible in- roams. terruption of normal electrical services resulting from similar causes as well as possible disruption of normal elec- Exc•eption: Heating of general patient rooms during dis- trical service due to internal wiring and equipment failures. ruptiom of'the normal source shall not be required under ant'of the following conditions: FPN: Facilities in which the normal source of power is supplied by two or more separate central station-fed ser- (1) The outside design temperature is higher than vices experience greater than normal electrical service reli- -6.7°C (20 0F). ability than those with only a single teed. Such a dual (2) The outside design temperature is lower than source of normal power consists of two or more electrical –6.7°C(207)and where a selected room(s) is provided for services fed from separate generator sets or a utility distri- the needs of all con fi zed patients, only such roona(s) need bution network that has multiple power input sources and is arranged to provide mechanical and electrical separation so be heated. that a fault between the facility and the generating sources (3) The facility is served by a dual source of normal will not likely cause an interruption of more than one of the power as described in 517.44(C), FPN. facility service feeders. FPN: The outside design temperature is based on the 97t/: 517.45 Essential Electrical Systems for Other Health percent design values as shown in Chapter 24 of the Care Facilities. ASHRAE Handbook of Frrndanientals (1997). (2) Elevator service — in instances where disruption of (A) Essential Electrical Distribution. The essential elec- power would result in elevators stopping between trical distribution system shall be a battery or generator floors, throw-over facilities shall be provided to allow system. the temporary operation of any elevator for the release FPN: See NFPA 99-2005, Standard for Health Care of passengers. For elevator cab lighting, control, and Facilities. signal system requirements, see 517.42(G). (3) Additional illumination, receptacles, and equipment shall (B) Electrical Life Support Equipment. Where electrical be permitted to be connected only to the critical branch. life support equipment is required, the essential electrical distribution system shall be as described in 517.30 through [99:4.5.2.2.3.4(A), (B), and (C)] 517.35. [99:14.3.4.2,1] 517.44 Sources of Power. (C) Critical Care Areas. Where critical care areas are present, the essential electrical distribution system shall be (A) Two Independent Sources of Power. Essential electri- as described in 517.30 through 517.35. f99:14.3.4.2.2] cal systems shall have a minimum of two independent sources of power: a normal source generally supplying the entire elec- (D) Power Systems. Battery systems shall be installed in trical system and one or more alternate sources for use when accordance with the requirements of Article 700, and gen- the normal source is interrupted. [99:4.4.1.1.4] erator systems shall be as described in 517.30 through 517.35. (B) Alternate Source of Power. The alternate source of power shall be a generators) driven by some form of prime IV- Inhalation Anesthetizing Locations mover(s) and located on the premises. FPN: For further information regarding safeguards for Exception No. 1: Where the normal source consists of gen- anesthetizing locations, see NFPA 99-2005, Standard for erating units on the premises, the alternate source shall be Health Care Facilities. either another generator set or an external utility service. Exception No. 2: Nursing homes or limited care facilities 517.60 Anesthetizing Location Classification. meeting the requirement of 517.40(A)and father health dare FPN: If either of the anesthetizing locations in 517.60(A) facilities meeting the requirement of 517.45 shall be per- or 517.60(B) is designated a wet procedure location, refer mitted to use a battery system or self-contained battery to 517.20. integral with the equipment. (A) Hazardous (Classified) Location. (C) Location of Essential Electrical System Compo- (1) Use Location.In a location where flammable anesthet- nents. Careful consideration shall be given to the location ics are employed,the entire area shall be considered to be a 2WS Edition NATIONAL ELECTRICAL CODE 70--437 517.61 ARTICLE 517--HEALTH CARE FACILITIES Class 1, Division I location that extends upward to a level hard usage in accordance with Table 400.4 and shall in- 1.52 m (5 ft) above the floor. The remaining volume up to clude an additional conductor for grounding. the structural ceiling is considered to be above a hazardous (classified) location. 199: Annex E, E.I, and E.2] (7) Flexible Cord Storage. A storage device for the flex- ible cord shall be provided and shall not subject the cord to (2) Storage Location. Any room or location in which bending at a radius of less than 75 mm (3 in.), flammable anesthetics or volatile flammable disinfecting agents are stored shall be considered to be a Class 1, Divi- (B) Above Hazardous (Classified}Anesthetizing sion 1 location from floor to ceiling. Locations. (B) Other-Than-Hazardous (Classified) Location. Any (1) Wiring Methods. Wiring above a hazardous (classi- fied) location referred to in 517.60 shall be installed in rigid inhalation anesthetizing location designated for the exclu- metal conduit,electrical metallic tubing, intermediate metal live use of nonflammable anesthetizing agents shall be con- conduit, Type MI cable, or Type MC cable that employs a sidered to be an other-than-Hazardous (classified) location, continuous, gaslvaportight metal sheath. 517.61 Wiring and Equipment. (2) Equipment Enclosure. Installed equipment that may produce arcs, sparks, or particles of hot metal, such as (A) Within Hazardous (Classified)Anesthetizing lamps and lampholders for fixed lighting,cutouts,switches, Locations. generators, motors, or other equipment having make-and- (1) Isolation. Except as permitted in 517.160, each power break or sliding contacts, shall be of the totally enclosed circuit within, or partially within, a flammable anesthetiz- type or be constructed so as to prevent escape of sparks or ing location as referred to in 517.60 shall be isolated from hot metal particles. any distribution system by the use of an isolated power Exception: Wall-mounted receptacles installed above the system. [99:Annex E, E.6.6.2] hazardous (classified) location in flammable anesthetizing (2) Design and Installation. Where an isolated power sys- locations shall not be required to be totally enclosed or tem is utilized, the isolated power equipment shall be listed have openings guarded or screened to prevent dispersion of as isolated power equipment, and the isolated power system particles. shall be designed and installed in accordance with 517.160. (3) Luminaires. Surgical and other luminaires shall con- (3) Equipment Operating at More Than 10 Volts. In form to 501.130(B). hazardous (classified) locations referred to in 517.60, all Exception No. 1: The surface temperature limitations set fixed wiring and equipment and all portable equipment, forth in 501.130(B)(1) shall not apply. including lamps and other utilization equipment, operating Exception No. 2: Integral or pendant switches that are lo- at more than 10 volts between conductors shall comply cated above and cannot be lowered into the hazardous with the requirements of 501.1 through 501.25, and (classified) location(,) shall not be required to be 501.100 through 501.150, and 501.30(A)and 501.30(B) for explosionproof. Class I, Division t locations. All such equipment shall be specifically approved for the hazardous atmospheres in- (4) Seals. Listed seals shall be provided in conformance volved. [99:Annex E, E.2.1, E.4.5, E.4.6, and E.4.71 with 501.15, and 501.15(A)(4) shall apply to horizontal as well as to vertical boundaries of the defined hazardous (4) Extent of Location. Where a box, fitting, or enclosure (classified) locations. is partially, but not entirely, within a hazardous (classified) location(s), the hazardous (classified) location(s) shall be (5) Receptacles and Attachment Plugs. Receptacles and considered to be extended to include the entire box, fitting, attachment plugs located above hazardous (classified) anes- or enclosure. thetizing locations shall be listed for hospital use for ser- vices of prescribed voltage, frequency, rating, and number (5) Receptacles and Attachment Plugs. Receptacles and of conductors with provision for the connection of the ground- attachment plugs in a hazardous (classified) location(s) ing conductor. This requirement shall apply to attachment shall be listed for use in Class 1, Group C hazardous (clas- plugs and receptacles of the 2-pole,3-wire grounding type for sified)locations and shall have provision for the connection single-phase, 120-volt, nominal, ac service. of a grounding conductor. (6) 250-Volt Receptacles and Attachment Plugs Rated (6) Flexible Cord Type. Flexible cords used in hazardous 50 and 60 Amperes. Receptacles and attachment plugs (classified) locations for connection to portable utilization rated 250 volts, for connection of 50-ampere and 60- equipment, including lamps operating at more than 8 volts ampere ac medical equipment for use above hazardous between conductors, shall be of a type approved for extra- (classified) locations, shall be arranged so that the 60- 70-438 NATIONAL ELECTRICAL CODE 2009 Edition ARTICLE 517—HEALTH CARE FACILITIES 517.63 ampere receptacle will accept either the 50-ampere or 517.63 Grounded Power Systems in Anesthetizing the 60-ampere plug. Fifty-ampere receptacles shall be Locations. designed so as not to accept the 60-ampere attachment plug. The attachment plugs shall be of the 2-pole, 3-wire (A) Battery-Powered )emergency Lighting Units.One or design with a third contact connecting to the insulated more battery-powered emergency lighting units shall be (green or green with yellow stripe) equipment grounding provided in accordance with 700.12{F). conductor of the electrical system. (B) Branch-Circuit Wiring. Branch circuits supplying only listed, fixed, therapeutic and diagnostic equipment, Locations.Other-Than-Hazardous (Classified) Anesthetizing permanently installed above the hazardous(classified)loca- tion and in other-than-hazardous (classified)locations,shall (1) Wiring Methods. Wiring serving other-than-hazardous be permitted to be supplied from a normal grounded ser- (classified) locations, as defined in 517.60, shall be in- vice, single- or three-phase system, provided the following stalled in a metal raceway system or cable assembly. The apply: metal raceway system or cable armor or sheath assembly (1) Wiring for grounded and isolated circuits does not oc- shall qualify as an equipment grounding conductor in accor- cupy the same raceway or cable. dance with 250.118.Type MC and Type MI cable shall have (2) All conductive surfaces of the equipment are connected an outer metal armor,sheath, or sheath assembly that is iden- to an equipment grounding conductor. tified as an acceptable equipment grounding conductor. (3) Equipment (except enclosed X-ray tubes and the leads Exception: Pendant receptacle constructions that employ. to the tubes) is located at least 2.5 m (8 ft) above the at least Tine SJO or equivalent flexible cords suspended floor or outside the anesthetizing location. not less than 1.8 in (6 ft)from the floor shall not be required (4) Switches for the grounded branch circuit are located to be installed in a metal raceway or cable assembl}: outside the hazardous (classified) location. (2) Receptacles and Attachment Plugs. Receptacles and Exception: Sections 517.63(B)(3) and (B)(4) shall not ap- attachment plugs installed and used in other-than-hazardous ply in other-than-hazardous (classified) locations. (classified) locations shall be listed "hospital grade" for services of prescribed voltage, frequency, rating, and nun- (C} Fixed Lighting Branch Circuits. Branch circuits bee of conductors with provision for connection of the supplying only fixed lighting shall be permitted to be grounding conductor. This requirement shall apply to supplied by a normal grounded service, provided the fol- 2-pole, 3-wire grounding type for single-phase, 120-, 208-, lowing apply: or 240-volt, nominal, ac service. (1) Such luminaires are located at least 2.5 m (8 ft) above the floor. (3) 250-Volt Receptacles and Attachment Plugs Rated (2) All conductive surfaces of luminaires are connected to 50 Amperes and 60 Amperes. Receptacles and attachment an equipment grounding conductor. plugs rated 250 volts, for connection of 50-ampere and {3} Wiring For circuits supplying power to luminaires does 60-ampere ac medical equipment for use in other-than- hazardous (classified) locations, shall be arranged so that not occupy the same raceway or cable for circuits sup- the 60-ampere receptacle will accept either the 50-ampere plying isolated power. or the 60-ampere plug. Fifty-ampere receptacles shall be (4) Switches are wall-mounted and located above hazard- designed so as not to accept the 60-ampere attachment ous (classified) locations. plug. The attachment plugs shall be of the 2-pole, 3-wire Exception: Sections 517.63(C)(1) and(C)(4) shall not ap- design with a third contact connecting to the insulated ply in other-titan-hazardous (classified) locations. (green or green with yellow stripe) equipment grounding conductor of the electrical system. (D) Remote-Control Stations. Wall-mounted remote- control stations for remote-control switches operating at 24 517.62 Grounding. In any anesthetizing area, all metal volts or less shall be permitted to be installed in any anes- raceways and metal-sheathed cables and all normally non— thetizing location. current-carrying conductive portions of fixed electrical equipment shall be connected to an equipment grounding (L} Location of Isolated Power Systems. Where an iso- eonductor. Grounding and bonding in Class I locations laced power system is utilized, the isolated power equip- ment shall be listed as isolated power equipment. Isolated shall comply with 501.30. power equipment and its grounded primary feeder shall be Exception: Equipment operating at not more than 10 volts permitted to be located in an anesthetizing location, pro- between conductors .shall not be required to be connected vided it is installed above a hazardous (classified) location to an equipment grounding conductor or in an other-than-hazardous (classified) location. 2008 Edition NATIONAL ELECTRICAL CODE 70-439 517.64 ARTICLE 517 HEALTH CARE FACILYCIES (F) Circuits in Anesthetizing Locations. Except as per- V. X-Ray Installations mitted above,each power circuit within, or partially within, a flammable anesthetizing location as referred to in 517.60 Nothing in this part shall be construed as specifying safe- s guards against the useful beam or stray X-ray radiation. hall be isolated from any distribution system supplying other-than-anesthetizing locations. FPN No. 1: Radiation safety and performance require- ments of several classes of X-ray equipment are regulated under Public Law 90-602 and are enforced by the Depart- 517.64 Low-Voltage Equipment and Instruments. ment of Health and Human Services. (A) Equipment Requirements, Low-voltage equipment FPN No. 2: In addition, information on radiation protec- that is frequently in contact with the bodies of persons or tion by the National Council on Radiation Protection and has exposed current-carrying elements shall comply with Measurements is published as Reports of the National Council on Radiation Protection and Measurement. These one of the following: reports are obtainable from NCRP Publications, P.O. Box (1) Operate on an electrical potential of 10 volts or less 30175,Washington, DC 20014. (2) Be approved as intrinsically safe or double-insulated 517.71 Connection to Supply Circuit. equipment (3) Be moisture resistant (A) Fixed and Stationary Equipment. Fixed and station- ary X-ray equipment shall he connected to the power sup- (B) Power Supplies. Power shall be supplied to low- ply by means of a wiring method complying with appli- voltage equipment from one of the following: cable requirements of Chapters 1 through 4 of this Code,as (1) An individual portable isolating transformer(autotrans- modified by this article. formers shall not be used) connected to an isolated Exception: Equipment properly supplied by a branch cir- power circuit receptacle by means of an appropriate cuit rated at not over 30 amperes shall be permitted to be cord and attachment plug supplied through a suitable attachment plug and hard- (2) A common low-voltage isolating transformer installed service cable or cord. in an other-than-hazardous (classified) location (3) Individual dry-cell batteries (B) Portable, Mobile, and Transportable Equipment. Individual branch circuits shall not be required for portable, (4) Common batteries made up of storage cells located in mobile, and transportable medical X-ray equipment requir- ing a capacity of not over 60 amperes. (C) Isolated Circuits. Isolating-type transformers for sup- (C) Over 600-Volt Supply. Circuits and equipment oper- plying low-voltage circuits shall have both of the following: ated on a supply circuit of over 600 volts shall comply with (1) Approved means for insulating the secondary circuit Article 490. from the primary circuit (2) The core and case connected to an equipment ground- 517.72 Disconnecting Means. ing conductor (A) Capacity.A disconnecting means of adequate capacity (D) Controls. Resistance or impedance devices shall be for at least 50 percent of the input required for the momen- permitted to control low-voltage equipment but shall not be tary rating or 100 percent of the input required for the used to limit the maximum available voltage to the equip- long-time rating of the X-ray equipment, whichever is ment. greater, shall be provided in the supply circuit. (E) Battery-Powered Appliances. Battery-powered appli- (B) Location. The disconnecting means shall be operable from a location readily accessible from the X-ray control. ances shall not be capable of being charged while in opera- tion unless their charging circuitry incorporates an integral (C) Portable Equipment. For equipment connected to a isolating-type transformer. 120-volt branch circuit of 30 amperes or less, a grounding- type attachment plug and receptacle of proper rating shall (F) Receptacles or Attachment Plugs. Any receptacle or be permitted to serve as a disconnecting means. attachment plug used on low-voltage circuits shall be of a type that does not permit interchangeable connection with 517.73 Rating of Supply Conductors and Overcurrent circuits of higher voltage. Protection. FPN: Any interruption of the circuit, even circuits as low (A) Diagnostic Equipment. as 10 volts, either by any switch or loose or defective con- nections anywhere in the circuit, may produce a spark that (1) Branch Circuits. The ampacity of supply branch- is sufficient to ignite flammable anesthetic agents. circuit conductors and the current rating of overcurrent pro- 70-440 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 517—HEALTH CARE FACILITIES 517.82 tective devices shall not be less than 50 percent of the trays or cable troughs along with X-ray equipment control momentary rating or 100 percent of the long-time rating, and power supply conductors without the need for barriers whichever is greater. to separate the wiring. (2) Feeders. The ampacity of supply feeders and the cur- 517.78 Guarding and Grounding, rent rating of overcurrent protective devices supplying two or more branch circuits supplying X-ray units shall not be (A) High-Voltage Parts. All high-voltage parts, including less than 50 percent of the momentary demand rating of the X-ray tubes, shall be mounted within grounded enclosures. largest unit plus 25 percent of the momentary demand rat- Air, oil,gas,or other suitable insulating media shall be used ing of the next largest unit plus 10 percent of the momen- to insulate the high-voltage from the grounded enclosure. tary demand rating of each additional unit. Where simulta- The connection from the high-voltage equipment to X-ray neous biplane examinations are undertaken with the X-ray tubes and other high-voltage components shall be made units, the supply conductors and overcurrent protective de- with high-voltage shielded cables. vices shall be 100 percent of the momentary demand rating of each X-ray unit. (B) Low-Voltage Cables. Low-voltage cables connecting FPN: The minimum conductor size for branch and feeder to oil-filled units that are not completely sealed, such as high-voltage i]d coolers, and hi formers, condensers, o circuits is also governed by voltage regulation require- trans g g ments. For a specific installation, the manufacturer usually switches, shall have insulation of the oil-resistant type. specifies minimum distribution transformer and conductor sizes, rating of disconnecting means, and overcurrent (C) Non—Current-Carrying Metal Parts. Non—current- protection. carrying metal parts of X-ray and associated equipment (B) Therapeutic Equipment.The ampacity of conductors (controls, tables, X-ray tube supports, transformer tanks, shielded cables, X-ray tube heads, etc.) shall be connected and rating of overcurrent protective devices shall not be to an equipment grounding conductor in the manner speci- less than 100 percent of the current rating or medical X-ray fled in Article 250, as modified by 517.13(A) and (B). therapy equipment. FPN: The ampacity of the branch-circuit conductors and the ratings or disconnecting means and overcurrent protec- Vi. Communications, Signaling Systems, Data tion for X-ray equipment are usually designated by the Systems, Fire Alarm Systems, and Systems Less manufacturer for the specific installation. Than 120 Volts, Nominal 517.74 Control Circuit Conductors. 517.80 Patient Care Areas. Equivalent insulation and iso- (A) Number of Conductors in Raceway. The number of lation to that required for the electrical distribution systems control circuit conductors installed in a raceway shall be in patient care areas shall be provided for communications, signaling systems, data system circuits, fire alarm systems, determined in accordance with 300.17. and systems less than 120 volts, nominal. (B) Minimum Size of Conductors. Size 18 AWG or 16 Secondary circuits of transformer-powered communica- AWG fixture wires as specified in 725.49 and flexible cords tions or signaling systems shall not be required to be en- shall be permitted for the control and operating circuits of closed in raceways unless otherwise specified by Chapter 7 X-ray and auxiliary equipment where protected by not or 8. 199.$•4.2.2.4.61 larger than 20-ampere overcurrent devices. FPN: An acceptable alternate means of providing isolation for patient/nurse call systems is by the use of nonelectrified 517.75 Equipment Installations. All equipment for new signaling, communications, or control devices held by the X-ray installations and all used or reconditioned X-ray patient or within reach of the patient. equipment moved to and reinstalled at a new location shall be of an approved type. 517.81 Other-Than-Patient-Care Areas. In other-than- patient-care areas, installations shall be in accordance with 517.76 Transformers and Capacitors. Transformers and the appropriate provisions of Articles 640, 725, 760, and capacitors that are part of X-ray equipment shall not be 800, required to comply with Articles 450 and 460. Capacitors shall be mounted within enclosures of insu- 517.82 Signal Transmission Between Appliances. lating material or grounded metal. (A) General. Permanently installed signal cabling from an 517.77 Installation of High-Tension X-Ray Cables. appliance in a patient location to remote appliances shall Cables with grounded shields connecting X-ray tubes and employ a signal transmission system that prevents hazard- image intensifiers shall be permitted to be installed in cable ous grounding interconnection of the appliances. 2008 Edition NATIONAL ELECTRICAL CODE 70--441 517.160 ARTICLE 517--HEALTH CARE FACILITIES FPN: See 517.13(A)for additional grounding requirements (b) Higher Voltages. Isolation transformers shall be in patient care areas. permitted to serve single receptacles in several patient areas where the following apply: (B) Common Signal Grounding Wire. Common signal {l} The receptacles are reserved for supplying power to grounding wires (i.e., the chassis ground for single-ended transmission) shall be permitted to be used between appli- equipment requiring 150 volts or higher, such as por- ances all located within the patient care vicinity, provided table X-ray units. the appliances are served from the same reference ground- (2) The receptacles and mating plugs are not interchange- able with the receptacles on the local isolated power ing point. system. [99:13.4.1.2.6.6] VII. Isolated Power Systems (5) Conductor Identification.The isolated circuit conduc- 517.160 Isolated Power Systems. tors shall be identified as follows: (A) Installations. (1) Isolated Conductor No. 1 -- Orange with a distinctive colored stripe other than white, green, or gray (1) Isolated Power Circuits. Each isolated power circuit (2) Isolated Conductor No. 2 — Brown with a distinctive shall be controlled by a switch that has a disconnecting pole colored stripe other than white, green, or gray in each isolated circuit conductor to simultaneously discon- For 3-phase systems, the third conductor shall be iden- nect all power. Such isolation shall be accomplished by tified as yellow with a distinctive colored stripe other than means of one or more isolation transformers, by means of white, green, or gray. Where isolated circuit conductors generator sets, or by means of electrically isolated batteries. supply 125-volt, single-phase, 15- and 20-ampere recep- (2) Circuit Characteristics. Circuits supplying primaries tacles,the striped orange conductor(s) shall be connected to of isolating transformers shall operate at not more than 600 the terminaI(s) on the receptacles that are identified in ac- volts between conductors and shall be provided with proper cordance with 200.10(B) for connection to the grounded overcurrent protection. The secondary voltage of such circuit conductor. transformers shall not exceed 600 volts between conductors (6) Wire-Pulling Compounds. Wire-pulling compounds of each circuit. All circuits supplied from such secondaries that increase the dielectric constant shall not be used on the shall be ungrounded and shall have an approved overcur- secondary conductors of the isolated power supply. rent device of proper ratings in each conductor. Circuits FPN No. 1: It is desirable to limit the size of the isolation supplied directly from batteries or from motor generator transformer to 10 kVA or less and to use conductor insula- sets shall be ungrounded and shall be protected against tion with low leakage to meet impedance requirements. overcurrent in the same manner as transformer-fed second- circuits. If an electrostatic shield is resent, it shall be FPN No. 2: Minimizing the length of branch-circuit con- ' p ductors and using conductor insulations with a dielectric connected to the reference grounding point. [99:4.3.2.6.1] constant less than 3.5 and insulation resistance constant greater than 6100 megohm-meters(20,000 megohm-Feet)at (3) Equipment Location. The isolating transformers, mo- 16°C (60°F)reduces leakage from line to ground,reducing for generator sets, batteries and battery chargers, and asso- the hazard current. ciated primary or secondary overcurrent devices shall not be installed in hazardous (classified) locations. The isolated (B) Line Isolation Monitor. secondary circuit wiring extending into a hazardous anes- (1) Characteristics. In addition to the usual control and thetizing location shall be installed in accordance with overcurrent protective devices, each isolated power system 501.10. shall be provided with a continually operating line isolation monitor that indicates total hazard current. The monitor shall (4) isolation Transformers.An isolation transformer shall be designed such that a green signal lamp,conspicuously vis- not serve more than one operating room except as covered ible to persons in each area served by the isolated power in (A)(4){a} and (A)(4)(b). system, remains lighted when the system is adequately iso- For purposes of this section, anesthetic induction rooms lated from ground.An adjacent red signal lamp and an audible are considered part of the operating room or rooms served warning signal(remote if desired)shall be energized when the by the induction rooms. total hazard current (consisting of possible resistive and ca- (a) Induction Roams. Where an induction room serves pacitive leakage currents) from either isolated conductor to more than one operating room, the isolated circuits of the ground reaches a threshold value of 5 mA under nominal line induction room shall be permitted to be supplied from the voltage conditions.The line monitor shall not alarm for a fault isolation transformer of any one of the operating rooms hazard of less than 3.7 mA or for a total hazard current of less served by that induction room. than 5 mA. 70-442 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 518 ASSEMBLY OCCUPANCIES 518.3 Exception: A .system .shrill be perntitted to be designed to Armories Exhibition halls operate at a lower threshold value of total hazard current. Assembly halls Gymnasiums A line isolation monitor for such a system shall be permit- Auditoriums Mortuary chapels red to be approved, with the provision that the fault hazard Bowling lanes Multipurpose rooms Club rooms Museums current shall be permitter)to be reduced but not to less than Conference roams Places of awaiting transportation 35 percent of the corresponding threshold value of the total Courtrooms Places of religious worship hazard current, and the monitor hazard current is to be Dance halls Pool rooms correspondingh'reduced to not more than 50 percent of the Dining and drinking Restaurants alarm threshold value of the total hazard current. facilities Skating rinks (2) Impedance. The line isolation monitor shall be de- signed to have sufficient internal impedance such that, (B) Multiple Occupancies.Where an assembly occupancy when properly connected to the isolated system, the maxi- forms a portion of a building containing other occupancies, mum internal current that can flow through the line isola- Article 518 applies only to that portion of the building tion monitor, when any point of the isolated system is considered an assembly occupancy. Occupancy of any grounded, shall be I mA. room or space for assembly purposes by less than 100 per- Exception: The line isolation tnonitor shall be permitted to sons in a building of other occupancy, and incidental to be of the low-impedance t pe such that the current through such other occupancy, shall be classified as part of the other the line isolation monitor, when any point of the isolated occupancy and subject to the provisions applicable thereto. .systenz is grounded, will not exceed twice the alarm thresh- old value for a period not exceeding 5 milliseconds. (C) Theatrical Areas. Where any such building structure, or portion thereof,contains a projection booth or stage plat- FPN: Reduction of the monitor hazard current, provided form or area for the presentation of theatrical or musical this reduction results in an increased"not alarm"threshold productions, either fixed or portable, the wiring for that value for the fault hazard current, will increase circuit capacity. area, including associated audience seating areas, and all (3) Ammeter. An ammeter calibrated in the total hazard equipment that is used in the referenced area, and portable current of the system (contribution of the fault hazard cur- equipment and wiring for use in the production that will not rent plus monitor hazard current) shall be mounted in a be connected to permanently installed wiring, shall comply plainly visible place on the line isolation monitor with the with Article 520. "alarm on" zone at approximately the center of the scale. FPN: For methods of determining population capacity, see Exception: The line isolation monitor shall be permitted to local building code or, in its absence, NFPA 101-2006,Life Code. be a composite unit, with a sensing .section cabled to u Safety separate displativ panel section on which the alann or test 518,3 Other Articles. fiozctions are located. (A) Hazardous (Classified)Areas. Electrical installations FPN: It is desirable to locate the ammeter so that it is in hazardous (classified) areas located in assembly occu- conspicuously visible to persons in the anesthetizing location. panties shall comply with Article 500. (B) Temporary Wiring. In exhibition halls used for dis- play booths, as in trade shows, the temporary wiring shall ARTICLE 518 be permitted to be installed in accordance with Article 590. Flexible cables and cords approved for hard or extra-hard Assembly Occupancies usage shall be permitted to be laid on floors where pro- tected from contact by the general public. The ground-fault 518.1 Scope. Except for the assembly occupancies explic- circuit-interrupter requirements of 590.6 shall not apply. itly covered by 520.1, this article covers all buildings or Exception: Where conditions of supervision and mainte- portions of buildings or structures designed or intended for nance ensure that only qualified persons will service the the gathering together of 100 or more persons for such in purposes corns or cables identified in Table purposes as deliberation, worship, entertainment, eating, 400.4 for hard usage or extra-hard usage shall be pennit- drinking, amusement, awaiting transportation, or similar ted in cable tra'vs used onl}•for temporary,wiring.All coals purposes. or cables shall be installed in a single layer. A permanent 518.2 General Classification. sign shall be attached to the cable tray at intervals not to (A) Examples. Assembly occupancies shall include, but exceed 7.5 nt 125 ft). The sign shall read not be limited to, the following: CABLE TRAY FOR TEMPORARY WIRING ONLY 2008 Edition NATIONAL ELECTRICAL CODE 70-443 518.4 ARTICLE 520—THEATERS,MOTION PICTURE AND TELEVISION STUDIOS,AND SIMILAR LOCATIONS (C) Emergency Systems. Control of emergency systems on the plane of the wood nearest the tire.A finish rating is shall comply with Article 700. not intended to represent a rating for a membrane ceiling. 518.4 Wiring Methods. 5185 Supply. Portable switchboards and portable power (A) General. The fixed wiring methods shall be metal distribution equipment shall be supplied only from listed raceways, flexible metal raceways, nonmetallic raceways power outlets of sufficient voltage and ampere rating. Such encased in not less than 50 mm (2 in.) of concrete, Type power outlets shall be protected by overcurrent devices. MI, MC, or AC cable. The wiring method Shall itself Such overcurrent devices and power outlets shall not be qualify as an equipment grounding conductor according to accessible to the general public. Provisions for connection 250.118 or shall contain an insulated equipment grounding of an equipment grounding conductor shall be provided. conductor sized in accordance with Table 250.122. The neutral conductor of feeders supplying solid-state phase control, 3-phase, 4-wire dimmer systems shall be Exception: Fixed wiring methods shall be as provided in considered a current-carrying conductor for purposes of de- (a) Audio signal processing, amplification, and repro- rating. The neutral conductor of feeders supplying solid- duction equipment--Article 640 state sine wave,3-phase,4-wire dimming systems shall not (b) Communications circuits—Article 800 be considered a current-carrying conductor for purposes of (c) Class 2 and Class 3 remote-control and signaling derating. circuits —Article 725 Exception: The neutral conductor of feeders supplying Sys- (d) Fire alarm circuits—Article 760 temS that use or may use both phase-control and.sine-wave (B) Nonrated Construction. In addition to the wiring dimmers Shall be considered as current-carrying for pur- methods of 518.4(A), nonmetallic-sheathed cable,Type AC poses of derating. cable, electrical nonmetallic tubing, and rigid nonmetallic FPN: For definitions of Solid-state dimmer types, See conduit shall be permitted to be installed in those buildings 520.2. or portions thereof that are not required to be of fire-rated construction by the applicable building code. FPN: Fire-rated construction is the fire-resistive classifica- tion used in building cosies. ARTICLE 520 (C) Spaces with Finish Rating. Electrical nonmetallic Theaters,Audience Areas of Motion tubing and rigid nonmetallic conduit shall be permitted to Picture and Television Studios, be installed in club rooms, conference and meeting rooms in hotels or motels, courtrooms, dining facilities, restau- rants, mortuary chapels, museums, libraries, and places of and.Similar Locations religious worship where the following apply: (1) The electrical nonmetallic tubing or rigid nonmetallic I. General conduit is installed concealed within walls, floors, and ceilings where the wails, floors, and ceilings 520.1 Scope. This article covers all buildings or that part provide a thermal barrier of material that has at least of a building or structure, indoor or outdoor, designed or a 15-minute finish rating as identified in listings of used for presentation, dramatic, musical, motion picture fire-rated assemblies, projection, or similar purposes and to specific audience (2) The electrical nonmetallic tubing or rigid nonmetallic seating areas within motion picture or television studios. conduit is installed above suspended ceilings where the suspended ceilings provide a thermal barrier of mate- 520.2 Definitions. rial that has at least a 15-minute finish rating as iden- Border Light.A permanently installed overhead strip light, tified in listings of fire-rated assemblies. Electrical nonmetallic tubing and rigid nonmetallic con- Breakout Assembly. An adapter used to connect a multi- duit are not recognized for use in other space used for pole connector containing two or more branch circuits to environmental air in accordance with 300.22(C). multiple individual branch-circuit connectors. FPN: A finish rating is established for assemblies contain- Bundled. Cables or conductors that are tied, wrapped, ing combustible (wood) supports. The finish rating is de- taped, or otherwise periodically bound together. tined as the time at which the wood stud or wood joist reaches an average temperature rise of 121°C(250°F)or an Connector Strip. A metal wireway containing pendant or individual temperature rise of 163°C (325°F) as measured flush receptacles. 70-144 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 520--THEATERS,MOTION PICTURE AND"TELEVISION STUDIOS,AND SIMILAR LOCATIONS 520.10 Drop Box. A box containing pendant- or flush-mounted containing an insulated equipment grounding conductor receptacles attached to a multiconductor cable via strain sized in accordance with Table 250.122. relief or a multipole connecter. Exception: Fixed wiring methods .shall be as provided in Footlight. A border light installed on or in the stage. Article 640 for audio si, nal processing, amplification, and Grouped. Cables or conductors positioned adjacent to one reproduction equipment, in Article 800 for communication another in Article 725 for Class 2 and Class 3 remote- control and signeding circuits, and in Article 760 for fire Performance Area. The stage and audience seating area alarm circuits. associated with a temporary stage structure, whether in- doors or outdoors,constructed of scaffolding, truss, platforms, (B) Portable Equipment. The wiring for portable switch- or similar devices,that is used for the presentation of theatrical boards,stage set lighting, stage effects, and other wiring not or musical productions or for public presentations. fixed as to location shall be permitted with approved flex- ible cords and cables as provided elsewhere in Article 520. Portable Equipment. Equipment fed with portable cords Fastening such cables and cords by uninsulated staples or or cables intended to be moved from one place to another. nailing shall not be permitted. Portable Power Distribution Unit. A power distribution box containing receptacles and overcurrent devices. (C) Nonrated Construction. Nonmetallic-sheathed cable, Type AC cable, electrical nonmetallic tubing, and rigid non- Proseenium. The wall and arch that separates the stage metallic conduit shall be permitted to be installed in those from the auditorium (house). buildings or portions thereof that are not required to be of Solid-State Phase-Control Dimmer. A solid-state dimmer fire-rated construction by the applicable building code. where the wave shape of the steady-state current does not 520.6 Number of Conductors in Raceway. The number follow the wave shape of the applied voltage, such that the of conductors permitted in any metal conduit, rigid nonme- wave Shape is nonlinear. tallic conduit as permitted in this article, or electrical me- Solid-State Sine Wave Dimmer. A solid-state dimmer tallic tubing for border or stage pocket circuits or for where the wave shape of the steady-state current follows remote-control conductors shall not exceed the percentage the wave Shape of the applied voltage such that the wave fill shown in Table t of Chapter 9. Where contained within shape is linear. an auxiliary gutter or a wireway, the sum of the cross- sectional areas of all contained conductors at any cross Stand Lamp (Work Light). A portable stand that contains section shall not exceed 20 percent of the interior cross- a general-purpose luminaire or lampholder with guard for sectional area of the auxiliary gutter or wireway. The 30- the purpose of providing general illumination on the stage conductor limitation of 366.22 and 376.22 shall not apply. or in the auditorium. Strip Light.A luminaire with multiple lamps arranged in 520.7 Enclosing and Guarding Live Parts. Live parts a row. shall be enclosed or guarded to prevent accidental contact by persons and objects. All switches shall be of the exter- Two-Fer. An adapter cable containing one male plug and nally operable type. Dimmers, including rheostats, shall be two female cord connectors used to connect two loads to placed in cases or cabinets that enclose all live parts. one branch circuit. 520.8 Emergency Systems.Control of emergency systems 520.3 Motion Picture Projectors. Motion picture equip- shall comply with Article 700. ment and its installation and use shall comply with Article 540. 520.9 Branch Circuits. A branch circuit of any size sup- 520.4 Audio Signal Processing, Amplification, and Re- plying one or more receptacles shall be permitted to supply production Equipment. Audio signal processing, amplifi- stage set lighting.The voltage rating of the receptacles shall cation,and reproduction equipment and its installation shall be not less than the circuit voltage. Receptacle ampere rat- ings and branch-circuit conductor ampacity shall be not less comply with Article 640. than the branch-circuit overcurrent device ampere rating. 520.5 Wiring Methods. Table 210.2](13)(2) shall not apply. (A) General.The fixed wiring method shall be metal race- 520.10 Portable Equipment. Portable stage and studio ways, nonmetallic raceways encased in at least 50 mm lighting equipment and portable power distribution equipment (2 in.) of concrete, Type MI cable, MC cable, or AC cable shall be permitted for temporary use outdoors, provided the 2008 Edition NATIONAL ELECTRICAL CODE 70-445 520.21 ARTICLE 520—THEATERS,MOTION PICTURE AND TELEVISION STUDIOS,AND SIMILAR LOCATIONS equipment is supervised by qualified personnel while ener- volts between conductors.The grounded conductor shall be gized and barriered from the general public. common to the input and output circuits. FPN: See 210.9 for circuits derived from autotransformers. II. Fixed Stage Switchboards (D) Solid-State-'lope Dimmers. The circuit supplying a 520.21 Dead Front. Stage switchboards shall be of the solid-state dimmer shall not exceed 150 volts between con- dead-front type and shall comply with Part IV of Article ductors unless the dimmer is listed specifically for higher 408 unless approved based on suitability as a stage switch- voltage operation. Where a grounded conductor supplies a board as determined by a qualified testing laboratory and dimmer,it shall be common to the input and output circuits. recognized test standards and principles. Dimmer chassis shall be connected to the equipment 520.22 Guarding Back of Switchboard. Stage switch- grounding conductor. boards having exposed live parts on the back of such 520.26 Type of Switchboard. A stage switchboard shall boards shall be enclosed by the building walls, wire mesh be either one or a combination of the types specified in grilles, or by other approved methods. The entrance to this 520.26(A), (B), and (C). enclosure shall be by means of a self-closing door. (A) Manual. Dimmers and switches are operated by 520.23 Control and Overcurrent Protection of Recep- handles mechanically linked to the control devices. tacle Circuits. Means shall be provided at a stage-lighting switchboard to which load circuits are connected for over- (B) Remotely Controlled. Devices are operated electri- current protection of stage-lighting branch circuits, includ- cally from a pilot-type control console or panel. Pilot con- ing branch circuits supplying stage and auditorium recep- trol panels either shall be part of the switchboard or shall be tacles used for cord-and-plug-connected stage equipment, permitted to be at another location. Where the stage switchboard contains dimmers to control nonstage lighting, the locating of the overcurrent protective (C} intermediate. A stage switchboard with circuit inter- devices for these branch circuits at the stage switchboard connections is a secondary switchboard (patch panel} or shall be permitted. panelboard remote to the primary stage switchboard. It shall contain overcurrent protection. Where the required 520.24 Metal Hood. A stage switchboard that is not com- branch-circuit overcurrent protection is provided in the pletely enclosed dead-front and dead-rear or recessed into a dimmer panel, it shall be permitted to be omitted from the wall shall be provided with a metal hood extending the full intermediate switchboard. length of the board to protect all equipment on the board 520.27 Stage Switchboard Feeders. from falling objects. (A) Type of Feeder.Feeders supplying stage switchboards 520.25 Dimmers. Dimmers shall comply with 520.25(A) shall be one of the types in 520.27(A)(1) through (A)(3). through {D}. (1) Single Feeder.A single feeder disconnected by a single (A) Disconnection and Overcurrent Protection. Where disconnect device. dimmers are installed in ungrounded conductors, each dim- mer shall have overcurrent protection not greater than (2) Multiple Feeders to Intermediate Stage Switch- 125 percent of the dimmer rating and shall be disconnected board (Patch Panel). Multiple feeders of unlimited quan- from all ungrounded conductors when the master or indi- tity shall be permitted,provided that all multiple feeders are vidual switch or circuit breaker supplying such dimmer is part of a single system. Where combined, neutral conduc- in the open position. tors in a given raceway shall be of sufficient ampacity to carry the maximum unbalanced current supplied by mul- (B) Resistance- or Reactor-Type Dimmers. Resistance- tiple feeder conductors in the same raceway, but they need or series reactor-type dimmers shall be permitted to be not be greater than the ampacity of the neutral conductor placed in either the grounded or the ungrounded conductor supplying the primary stage switchboard. Parallel neutral of the circuit. Where designed to open either the supply conductors shall comply with 310.4, circuit to the dimmer or the circuit controlled by it, the Switch- dimmer shall then comply with 404.2(B). Resistance- or {3) Separate Feeders to Single Primary Stage Switch- reactor-type dimmers placed in the grounded neutral con- board (Dimmer Bank). Installations with separate feeders ductor of the circuit shall not open the circuit. to a single primary stage switchboard shall have a disconnect- ing means for each feeder. The primary stage switchboard (C) Autotransformer-Type Dimmers.The circuit supply- shall have a permanent and obvious label stating the number ing an autotransformer-type dimmer shall not exceed 150 and location of disconnecting means. If the disconnecting 70-446 NATIONAL E1,ECPRICAL CODE 2008 Edition ARTICLE 520—THEATERS,MOTION PICTURE AND TELEVISION STUDIOS, AND SIMILAR LOCATIONS 520.45 means are located in more than one distribution switchboard, 520.43 Footlights. the primary stage switchboard shall be provided with barriers to correspond with these multiple locations. (A) Metal Trough Construction. Where metal trough construction is employed for footlights, the trough contain- (B) Neutral Conductor. For the purpose of derating, the ing the circuit conductors shall be made of sheet metal not following shall apply: lighter than 0.81 mm (0.032 in.) and treated to prevent (1) The neutral conductor of feeders supplying solid-state, oxidation. Lampholder terminals shall be kept at least phase-control 3-phase, 4-wire dimming systems shall 13 mm (1/2 in.) from the metal of the trough. The circuit be considered a current-carrying conductor. conductors shall be soldered to the lampholder terminals. (2) The neutral conductor of feeders supplying solid-state, sine wave 3-pbase, 4-wire dimming systems shall not (B) Other-Than-Metal Trough Construction. Where the be considered a current-carrying conductor. metal trough construction specified in 520.43(A) is not used, footlights shall consist of individual outlets with ]am- (3) The neutral conductor of feeders Supplying Systems phoiders wired with rigid metal conduit, intermediate metal that use or may use both phase-control and sine wave conduit, or flexible metal conduit, Type MC cable, or dimmers shall be considered a5 current-carrying. mineral-insulated, metal-sheathed cable. The circuit con- (C) Supply Capacity. For the purposes of calculating sup- ductors shall be soldered to the lampholder terminals. ply capacity to switchboards, it shall be permissible to con- sider the maximum load that the switchboard is intended to (C) Disappearing Footlights. Disappearing footlights control in a given installation, provided that the following shall be arranged so that the current supply is automatically apply: disconnected when the footlights are replaced in the storage (I) All feeders supplying the switchboard shall be pro- recesses designed for them. tected by an overcurrent device with a rating not greater than the ampacity of the feeder. 520.44 Borders and Proscenium Sidelights. (2) The opening of the overcurrent device shall not affect (A) General. Borders and proscenium sidelights shall be the proper operation of the egress or emergency light- as follows: ing systems. (1) Constructed as specified in 520.43 FPN: For calculation of stage switchboard feeder loads, (2) Suitably stayed and supported see 220.40. (3) Designed so that the flanges of the reflectors or other adequate guards protect the lamps from mechanical 11II. Fixed Stage Equipment Other Than Switchboards damage and from accidental contact with scenery or 520.41 Circuit Loads. other combustible material (A) Circuits Rated 20 Amperes or Less. Footlights, bor- (B) Cords and Cables for Border Lights. der lights, and proscenium sidelights shall be arranged so that no branch circuit supplying such equipment carries a (1) General. Cords and cables for supply to border lights load exceeding 20 amperes. shall be listed for extra-hard usage. The cords and cables shall be suitably supported. Such cords and cables shall be (B) Circuits Rated Greater Than 20 Amperes. Where employed only where flexible conductors are necessary. only heavy-duty lampholders are used, such circuits shall Ampacity of the conductors shall be as provided in 400.5. be permitted to comply with Article 210 for circuits sup- plying heavy-duty lampholders. (2) Cords and Cables Not in Contact with Heat- Producing Equipment. Listed multiconductor extra-hard- 520.42 Conductor Insulation. Foot, border, proscenium, usage-type cords and cables not in direct contact with or portable strip lights and connector strips shall be wired equipment containing heat-producing elements shall be per- with conductors that have insulation suitable for the tem- mitted to have their ampacity determined by Table 520.44. perature at which the conductors are operated, but not less Maximum load current in any conductor with an ampacity than 125°C (257 17). The ampacity of the 125°C (257°F) determined by Table 520.44 shall not exceed the values in conductors shall be that of 60°C (1407) conductors. All Table 520.44. drops from connector strips shall be 90°C (194°F) wire sized to the ampacity of 60°C (140°F) cords and cables with no 520.45 Receptacles. Receptacles for electrical equipment more than 150 mm (6 in.) of conductor extending into the on stages shall be rated in amperes. Conductors supply- connector strip. Section 310.15(B)(2)(a) shall not apply. ing receptacles shall be in accordance with Articles 310 FPN: See Table 310.13(A) for conductor types. and 400. 2(X)8 Edition NATIONAL ELECTRICAL CODE 70-447 520,46 ARTICLE 520—THEATERS,MOTION PICTURE AND TELEVISION STUDIOS,AND SIMILAR LOCATIONS Table 520.44 Ampacity of Listed Extra-Hard-Usage Cords and Exception: Decorative lamps installed in scenery shall not Cables with Temperature Ratings of 75°C (167°F)and 90°C be considered to be backstage lam f or the purpose of this (194°F)* (Based on Ambient Temperature of 30°C(86 0F)] section. Temperature Rating of 520.48 Curtain Machines. Curtain machines shall be Cords and Cables Maximum Rating of listed, Size 75°C 90°C Overcurrent (AWG) (167°F) (194°F) Device 520.49 Smoke Ventilator Control. Where stage smoke ventilators are released by an electrical device, the circuit 14 24 28 15 operating the device shall be normally closed and shall be 12 32 35 20 controlled by at least two externally operable switches, one 10 41 47 25 8 57 65 35 switch being placed at a readily accessible location on stage 6 77 87 45 and the other where designated by the authority having 4 101 114 60 jurisdiction. The device shall be designed for the full volt- 2 133 152 80 age of the circuit to which it is connected, no resistance * Ampacity shown is the ampacity for multiconductor cords and being inserted.The device shall be located in the loft above cables where only three copper conductors are current-carrying as the scenery and shall be enclosed in a suitable metal box described in 400.5. If the number of current-carrying conductors in a having a tight, self-closing door. cord or cable exceeds three and the load diversity factor is a minimum of 50 percent, the ampacity of each conductor shall be reduced as shown in the following table: IV. Portable Switchboards on Stage Number of Conductors Percent of Ampacity 520.50 Road Show Connection Panel (A Type of Patch 4--6 80 Panel). A panel designed to allow for road show connec- 7-24 70 tion of portable stage switchboards to fixed lighting outlets 25-42 60 by means of permanently installed supplementary circuits. 43 and above 50 The panel, supplementary circuits, and outlets shall comply Note: Ultimate insulation temperature. In no case shall conductors be with 520.50(A) through (D). associated together in such a way with respect to the kind of circuit, the wiring method used, or the number of conductors such that the {A) Load Circuits. Circuits shall terminate in grounding- temperature limit of the conductors is exceeded. type polarized inlets of current and voltage rating that A neutral conductor that carries only the unbalanced current from match the fixed-load receptacle. other conductors of the same circuit need not be considered as a current-carrying conductor. (B) Circuit Transfer. Circuits that are transferred between In a 3-wire circuit consisting of two phase COndaetOrS and the fixed and portable switchboards shall have all circuit con- neutral conductor of a 4-wire, 3-phase, wye-connected system, the ductors transferred simultaneously. neutral conductor carries approximately the same current as the line- to-neutral currents of the other conductors and shall be considered to be a current-carrying conductor. (C) Overcurrent Protection. The supply devices of these On a 4-wire. 3-phase, wye circuit where the major portion of the supplementary circuits shall be protected by branch-circuit load consists of nonlinear loads such as electric-discharge lighting, overeurrent protective devices. The individual supplemen- electronic computer/data processing, or similar equipment, there are tary circuit, within the road show connection panel and harmonic currents present in the neutral conductor, and the neutral conductor shall be considered to be acurrent-carrying conductor. theater, shall be protected by branch-circuit overcurrent protective devices of suitable ampacity installed within the 520.46 Connector Strips, Drop Boxes, Floor Pockets, road show connection panel. and Other Outlet Enclosures.Receptacles for the connec- tion of portable stage-lighting equipment shall be pendant with Enclosure. Panel construction shall be in accordance with Article 408. or mounted in suitable pockets or enclosures and Shall com- ply with 520.45. Supply cables for connector strips and 520.51 Supply. Portable switchboards shall be supplied drop boxes shall be as specified in 520.44(B). only from power outlets of sufficient voltage and ampere rating. Such power outlets shall include only externally op- 520.47 Backstage Lamps (Bare Bulbs). Lamps (bare erable,enclosed fused switches or circuit breakers mounted bulbs) installed in backstage and ancillary areas where they on stage or at the permanent switchboard in locations can come in contact with scenery shall be located and readily accessible from the stage floor. Provisions for con- guarded so as to be free from physical damage and shall nection of an equipment grounding conductor shall be pro- provide an air space of not less than 50 mm(2 in.)between vided. For the purposes of conductor derating, the require- such lamps and any combustible material. ments of 520.27(B) shall apply. 70-448 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 520—THEATERS.MOTION PICTURE AND TELEVISION STUDIOS,AND SIMILAR LOCATIONS 520.53 520.52 Overcurrent Protection. Circuits from portable that it supplies.Circuit interrupting and bus bracing shall be switchboards directly supplying equipment containing in- in accordance with 110.9 and 110.10.The short-circuit cur- candescent lamps of not over 300 watts shall be protected rent rating shall be marked on the switchboard. by overcurrent protective devices having a rating or setting Conductors shall be enclosed in metal wireways or shall of not over 20 amperes. Circuits for lampholders over 300 be securely fastened in position and shall be bushed where watts shall be permitted where overcurrent protection cam- they pass through metal. plies with Article 210. (G) Pilot Light. A pilot light shall be provided within the enclosure and shall be connected to the circuit supplying 520.53 Construction and Feeders. Portable switchboards the board so that the opening of the master switch does not and feeders for use on stages shall comply with 520.53(A) cut off the supply to the lamp. This lamp shall be on an through M. individual branch circuit having overcurrent protection (A) Enclosure. Portable switchboards shall be placed rated or set at not over 15 amperes. within an enclosure of substantial construction, which shall (H) Supply Conductors. be permitted to be arranged so that the enclosure is open during operation. Enclosures of wood shall be completely (1) General.The supply to a portable switchboard shall be lined with sheet metal of not less than 0.51 mm (0.020 in.) by means of listed extra-hard usage cords or cables. The and shall be well galvanized, enameled, or otherwise prop- supply cords or cable shall terminate within the switch- erly coated to prevent corrosion or be of a corrosion- board enclosure, in an externally operable fused master switch or circuit breaker or in a connector assembly iden- resistant material. tified for the purpose. The supply cords or cable (and con- (B) Energized Parts. There shall not be exposed ener- nectar assembly) shall have sufficient ampacity to carry the total load connected to the switchboard and shall be pro- tected by overcurrent devices. (C) Switches and Circuit Breakers. All switches and (2) Single-Conductor Cables. Single-conductor portable circuit breakers shall be of the externally operable, en- supply cable sets shall be not smaller than 2 AWG conduc- closed type. tors. The equipment grounding conductor shall not be smaller than 6 AWG conductor. Single-conductor grounded (D) Circuit Protection. Overcurrent devices shall be pro- neutral cables for a supply shall be sized in accordance with vided in each ungrounded conductor of every circuit sup- 520.53(0)(2). Where single conductors are paralleled for plied through the switchboard.Enclosures shall be provided increased ampacity, the paralleled conductors shall be of for all overcurrent devices in addition to the switchboard the same length and size. Single-conductor supply cables enclosure. shall be grouped together but not bundled. The equipment grounding conductor shall be permitted to be of a different (E) Dimmers. The terminals of dimmers shall be provided type, provided it meets the other requirements of this sec- with enclosures, and dimmer faceplates shall be arranged tion, and it shall be permitted to be reduced in size as such that accidental contact cannot be readily made with permitted by 250.122. Grounded (neutral) and equipment the faceplate contacts. grounding conductors shall be identified in accordance with 200.6, 250.119, and 310.12. Grounded conductors shall be (F) Interior Conductors. permitted to be identified by marking at least the first 150 mm (6 in.) from both ends of each length of conductor (]} Type. All conductors other than busbars within the with white or gray. Equipment grounding conductors shall switchboard enclosure shall be stranded. Conductors shall be permitted to be identified by marking at least the first be approved for an operating temperature at least equal to the 150 mm (6 in.) from bath ends of each length of conductor approved operating temperature of the dimming devices used with green or green with yellow stripes. Where more than in the switchboard and in no case less than the following: one nominal voltage exists within the same premises, each (1) Resistance-type dimmers — 200°C (392°F); or ungrounded conductor shall be identified by system. (2) Reactor-type, autotransformer, and solid-state dimmers (3) Supply Conductors Not Over 3.0 m (10 ft) Long. -- 125°C (257°F) Where supply conductors do not exceed 3.0 m (10 ft) in All control wiring shall comply with Article 725. length between supply and switchboard or supply and a subsequent overcurrent device, the supply conductors shall (2) Protection. Each conductor shall have an ampacity not be permitted to be reduced in size where all of the follow- less than the rating of the circuit breaker, switch, or fuse ing conditions are met: 2008 Editi[m NATIONAL ELECTRICAL CODE 70-449 520.53 ARTICLE 520—THEATERS,MOTION PICTURE AND TELEVISION STUDIOS,AND SIMILAR LOCATIONS (1) The ampacity of the supply conductors shall be at least (I) Cable Arrangement. Cables shall be protected by one-quarter of the ampacity of the supply overcurrent bushings where they pass through enclosures and shall be protection device. arranged so that tension on the cable is not transmitted to (2) The supply conductors shall terminate in a single over- the connections. Where power conductors pass through current protection device that will limit the load to the metal, the requirements of 300.20 shall apply. ampacity of the supply conductors.This single overcur- rent device shall be permitted to supply additional (,)) Number of Supply Interconnections. Where connec- overcurrent devices on its load side. tors are used in a supply conductor, there shall be a maxi- mum number of three interconnections (mated connector (3) The supply conductors shall not penetrate walls, floors, pairs) where the total length from supply to switchboard or ceilings or be run through doors or traffic areas. The does not exceed 30 m (100 ft). In cases where the total supply conductors shall be adequately protected from length from supply to switchboard exceeds 30 m (100 ft), physical damage, one additional interconnection shall be permitted for each (4) The supply conductors shall be suitably terminated in additional 30 m (100 ft) of supply conductor. an approved manner. (5) Conductors shall be continuous without splices or (K) Single-Pole Separable Connectors. Where single- connectors. pole portable cable connectors are used, they shall be listed (6) Conductors shall not be bundled. and of the locking type. Sections 400.10, 406.6, and 406.7 (7) Conductors shall be supported above the floor in an shall not apply to listed single-pole separable connectors and single-conductor cable assemblies utilizing listed approved manner. single-pole separable connectors. Where paralleled sets of (4) Supply Conductors Not Over 6.0 m (20 ft) Long. current-carrying, single-pole separable connectors are pro- Where supply conductors do not exceed 6.0 m (20 ft) in vided as input devices, they shall be prominently labeled length between supply and switchboard or supply and a with a warning indicating the presence of internal parallel subsequent overcurrent protection device, the supply con- connections. The use of single-pole separable connectors ductors shall be permitted to be reduced in size where all of shall comply with at least one of the following conditions: the following conditions are met: (1) Connection and disconnection of connectors are pos- (1) The ampacity of the supply conductors shall be at least sible only where the supply connectors are interlocked one-half of the ampacity of the supply overcurrent pro- to the source and it is not possible to connect or dis- tection device. connect connectors when the supply is energized. (2) The supply conductors shall terminate in a single over- (2) Line connectors are of the listed sequential-interlocking current protection device that limits the load to the type so that Ioad connectors shall be connected in the ampacity of the supply conductors.This single overcur- following sequence: rent device shall be permitted to supply additional a. Equipment grounding conductor connection overcurrent devices on its load side. b. Grounded circuit conductor connection, if provided (3) The supply conductors shall not penetrate walls, floors, c. Ungrounded conductor connection, and that discon- or ceilings or be run through doors or traffic areas. The nection shall be in the reverse order supply conductors shall be adequately protected from physical damage. (3) A caution notice shall be provided adjacent to the line connectors indicating that plug connection shall be in (4) The supply conductors shall be suitably terminated in the following order: an approved manner. a. Equipment grounding conductor connectors (5) The supply conductors shall be supported in an ap- b. Grounded circuit conductor connectors, if provided proved manner at least 2.1 m (7 ft) above the floor c. Ungrounded conductor connectors, and that discon- except at terminations. nection shall be in the reverse order (6) The supply conductors shall not be bundled. (7) Tap conductors shall be in unbroken lengths. (L) Protection of Supply Conductors and Connectors. All supply conductors and connectors shall be protected (5) Supply Conductors Not Reduced in Size. Supply against physical damage by an approved means. This pro- conductors not reduced in size under provisions of tection shall not be required to be raceways. 520.53(H)(3) or (H)(4) shall be permitted to pass through holes in walls specifically designed for the purpose. If pen- (M) Flanged Surface Inlets. Flanged surface inlets (re- etration is through the fire-resistant--rated wall,it shall be in cessed plugs) that are used to accept the power shall be accordance with 300.21. rated in amperes. 70-450 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 520—THEATERS. MOTION PICTURE AND TELEVISION STUDIOS. AND SIMILAR LOCATIONS 520.63 (N) Terminals. Terminals to which stage cables are con- (a) Employ listed ntultipole connectors suitable for the nected shall be located so as to permit convenient access to purpose far even•supply interconnection the terminals. (b) Prevent access to all supply connections by the general public (0) Neutral Conductor. (c) Employ listed extra-hard usage multiconductor cords or cables with an ampacity suitable for the type of (1) Neutral Terminal. [n portable switchboard equipment load card not less than the ampere rating of the connectors.designed for use with 3-phase, 4-wire with ground supply, the supply neutral terminal, its associated bulbar, or equivalent wiring, or both, shall have an ampacity equal to V. Portable Stage Equipment Other Than at least twice the ampacity of the largest ungrounded sup- Switchboards ply terminal. 520.61 Are Lamps. Arc lamps, including enclosed arc Exception: Where portable switchboard equipment is spe- lamps and associated ballasts, shall be listed. Interconnect- cifically constructed and identified to be internally con- ing cord sets and interconnecting cords and cables shall be verted in the field, in an approved manner;from use with a extra-hard usage type and listed. balanced 3-phase, 4-wire with ground supply to a balanced single-phase, 3-wire with ground supph: the supply neutral 520.62 Portable Power Distribution Units. Portable terminal and its associated busbar, equivalent wiring, or power distribution units shall comply with 520.62(A) both, shall have an ampacity equal to at least that of the through (E). largest ungrounded single-phase supply terminal. (A) Enclosure. The construction shall be such that no (2) Supply Neutral Conductor. The power supply con- current-carrying part will be exposed. ductors for portable switchboards utilizing solid-state (B) Receptacles and Overcurrent Protection. Recep- phase-control dimmers shall be sized considering the neu- tacles shall comply with 520.45 and shall have branch- tral conductor as a current-carrying conductor for derating circuit overcurrent protection in the box. Fuses and circuit purposes. The power supply conductors for portable breakers shall be protected against physical damage. Cords switchboards utilizing only solid-state sine wave dimmers or cables supplying pendant receptacles shall be listed for shall be sized considering the neutral conductor as a non- extra-hard usage. current-carrying conductor for derating purposes. Where single-conductor feeder cables, not installed in raceways, (C) Busbars and Terminals. Busbars shall have an am- are used on multiphase circuits feeding portable switch- parity equal to the sum of the ampere ratings of all the boards containing solid-state phase-control dimmers, the circuits connected to the busbar. Lugs shall be provided for neutral conductor shall have an ampacity of at least the connection of the master cable. 130 percent of the ungrounded circuit conductors feeding the portable switchboard.Where such feeders are supplying (D) Flanged Surface Inlets. Flanged surface inlets (re- only solid-state sine wave dimmers, the neutral conductor cessed plugs) that are used to accept the power shall be shall have an ampacity of at least 100 percent of the un- rated in amperes. grounded circuit conductors feeding the portable switch- (E) Cable Arrangement.Cables shall be adequately pro- board. tected where they pass through enclosures and be ar- (P) Qualified Personnel. The routing of portable supply ranged so that tension on the cable is not transmitted to conductors, the making and breaking of supply connectors the terminations. and other supply connections, and the energization and de- 520.63 Bracket Fixture Wiring. energization of supply services shall be performed by quali- fied personnel, and portable switchboards shall be so (A) Bracket Wiring. Brackets for use on scenery shall be marked, indicating this requirement in a permanent and wired internally, and the fixture stem shall be carried conspicuous manner. through to the back of the scenery where a bushing shall be placed on the end of the stem. Externally wired brackets or Exception: A portable switchboard shall be permitted to be other fixtures shall be permitted where wired with cords connected to a permanently installed supply receptacle by designed for hard usage that extend through scenery and other than qualified personnel, provided that the ,supply without joint or splice in canopy of fixture back and termi- rec•eptacle is protected for its rated ampacity by an over- nate in an approved-type stage connector located, where current device of riot greater than 150 amperes, and where practical, within 450 mm (18 in.) of the fixture. the receptacle, interconnection, and switchboard comply with all of the following: (B) Mounting.Fixtures shall be securely fastened in place. 2008 Edi[iun NATIONAL ELECTRICAL COoE 70-451 520.64 ARTICLE 520—THEATERS,MOTION PICTURE AND TELEVISION STUDIOS,AND SIMILAR LOCATIONS 520.64 Portable Strips. Portable strips shall be con- employ alternate, suitable conductors as determined by a structed in accordance with the requirements for border qualified testing laboratory and recognized test standards. lights and proscenium sidelights in 520,44(A). The supply cable shall be protected by bushings where it passes (4) Breakouts. Listed, hard usage (junior hard service) through metal and shall be arranged so that tension on the cords shall be permitted in breakout assemblies where all of cable will not be transmitted to the connections. the following conditions are met: (1) The cords are utilized to connect between a single mul- FPN No. 1: See 520.42 for wiring of portable strips. tipole connector containing two or more branch circuits FPN No. 2: See 520.68(A)(3) for insulation types required and multiple 2-pole, 3-wire connectors. on single conductors. (2) The longest cord in the breakout assembly does not exceed 6.0 m (20 ft). 520.65 Festoons. Joints in festoon wiring shall be stag- (3) The breakout assembly is protected from physical dam- gered. Lamps enclosed in lanterns or similar devices of age by attachment over its entire length to a pipe,truss, combustible material shall be equipped with guards. tower, scaffold, or other substantial support structure. 520.66 Special Effects. Electrical devices used for simu- (4) All branch circuits feeding the breakout assembly are lating lightning, waterfalls, and the like shall be constructed protected by overcurrent devices rated at not over 20 and located so that flames, sparks, or hot particles cannot amperes. come in contact with combustible material. (B) Conductor Ampaeity. The ampacity of conductors shall be as given in 400.5, except multiconductor, listed, 520.67 Multipole Branch-Circuit Cable Connectors. extra-hard usage portable cords that are not in direct con- Multipole branch-circuit cable connectors, male and fe- tact with equipment containing heat-producing elements male, for flexible conductors shall be constructed so that shall be permitted to have their ampacity determined by tension on the cord or cable is not transmitted to the con- Table 520.44.Maximum load current in any conductor with nections. The female half shall be attached to the load end an ampacity determined by Table 520.44 shall not exceed of the power supply card or cable. The connector shat] be the values in Table 520.44. rated in amperes and designed so that differently rated de- vices cannot be connected together; however, a 20-ampere Excepdon: Where alternate conductors are allowed in T slot receptacle shall be permitted to accept a 15-ampere 520.68(A)(3), their ampacity shall be as given in the appro- attachment plug of the same voltage rating. Alternating- priate table in this Cade for the types of conductors current multipole connectors shall be polarized and comply employed. with 406.6 and 4069. 520.69 Adapters. Adapters, two-fers, and other single- FPN: See 400.10 for pull at terminals. and multiple-circuit outlet devices shall comply with 520.68 Conductors for Portables. 520.69{A}, (B), and (C). (A) No Reduction in Current Rating. Each receptacle (A} Conductor Type. and its corresponding cable shall have the same current and (1) General. Flexible conductors, including cable exten- voltage rating as the plug supplying it. It shall not be uti- sions, used to supply portable stage equipment shall be lized in a stage circuit with a greater current rating. listed extra-hard usage cords or cables. (B) Connectors. All connectors shall be wired in accor- (2) Stand Lamps. Listed, hard usage cord shall be permit- dance with 520.67. ted to supply stand lamps where the cord is not subject to physical damage and is protected by an overcurrent device (C) Conductor Type. Conductors for adapters and two- rated at not over 20 amperes. fern shall be listed, extra-hard usage or listed, hard usage (junior hard service) cord. Hard usage (junior hard service) (3) High-Temperature Applications. A special assembly cord shall be restricted in overall length to 1.0 m (3.3 ft). of conductors in sleeving not longer than 1.0 m (3.3 ft) shall be permitted to be employed in lieu of flexible cord if the individual wires are stranded and rated not less than VI. Dressing Rooms 125°C (257°F) and the outer sleeve is glass fiber with a 520.71 Pendant Lampholders.Pendant lampholders shall wall thickness of at least 0.635 mm (0.025 in.). not be installed in dressing rooms. Portable stage equipment requiring flexible supply con- ductors with a higher temperature rating where one end is 520.72 Lamp Guards. All exposed incandescent lamps in permanently attached to the equipment shall be permitted to dressing rooms, where less than 2.5 m (8 ft) from the floor, 70-152 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 522—CONTROI.SYSTEMS FOR PERMANENT AMUSEMENT ATTRACTIONS 522.10 shall be equipped with open-end guards riveted to the outlet Ride Device. A device or combination of devices that box cover or otherwise sealed or locked in place. carry, convey, or direct a person(s) over or through a fixed or restricted course within a defined area for the primary 520.73 Switches Required. All lights and any receptacles purpose of amusement or entertainment. adjacent to the mirror(s) and above the dressing table counter(s)installed in dressing rooms shall be controlled by 522.3 Other Articles. Wherever the requirements of other wall switches installed in the dressing room(s). Each switch articles of this Carle and Article 522 differ,the requirements controlling receptacles adjacent to the mirror(s) and above of Article 522 shall apply. the dressing table counter(s) shall be provided with a pilot light located outside the dressing room,adjacent to the door 5225 Voltage Limitations. Control voltage shall be a to indicate when the receptacles are energized. Other out- maximum of 150 volts, nominal, ac to ground or 300 volts lets installed in the dressing room shall not be required to do to ground. be switched. 522.7 Maintenance. The conditions of maintenance and supervision shall ensure that only qualified persons service VII. Grounding the permanent amusement attraction. 520.81 Grounding. All metal raceways and metal- sheathed cables shall be connected to an equipment ground- I1. Control Circuits. ing conductor. The metal frames and enclosures of all 522,10 Power Sources for Control Circuits. equipment, including border lights and portable luminaires, shall be connected to an equipment grounding conductor. (A) Power-Limited Control Circuits. Power-limited con- trol circuits shall be supplied from a source that has a rated output of not more than 30 volts and 1000 volt-amperes. (1) Control Transformers. Transformers used to supply ARTICLE 522 power-limited control circuits shall comply with the appli- Controa Systems for Permanent cable sections within Parts I and II of Article 450. Amusement Attractions (2) Other Power-Limited Control Power Sources. Power-limited control power sources, other than transform- ers, shall be protected by overcurrent devices rated at not 1. General. more than 167 percent of the volt-ampere rating of the 522.1 Scope. This article covers the installation of control Source divided by the rated voltage.The fusible overcurrent circuit power sources and control circuit conductors for devices shall not be interchangeable with fusible overcur- electrical equipment, including associated control wiring in rent devices of higher ratings. The overcurrent device shall or on all structures, that are an integral part of a permanent be permitted to be an integral part of the power source. To comply with the 1000 volt-ampere limitation of amusement attraction. To the maximum output of power sources, other than transformers, shall be limited to 2500 volt-amperes, 522.2 Definitions. and the product of the maximum current and maximum Control Circuit. For the purposes of this article, the circuit voltage shall not exceed 10,000 volt-amperes.These ratings of a control system that carries the electrical signals direct- shall be determined with any overcurrent-protective device ing the performance of the controller but does not carry the bypassed. main power current. (B) Non—Power-Limited Control Circuits. Non--power- Entertainment Device.A mechanical or electromechanical limited control circuits shall not exceed 300 volts. The device that provides an entertainment experience. power output of the source shall not be required to be limited. FPN: These devices may include animated props. show action equipment, animated figures, and special effec,s,co- (1) Control Transformers. Transformers used to supply ordinated with audio and lighting to provide an entertain- non—power-limited control circuits shall comply with the ment experience. applicable sections within Parts I and II of Article 450. Permanent Amusement Attraction. Ride devices, enter- (2) Other Non—Power-Limited Control Power Sources. tainment devices, or combination thereof, that are installed Non--power-limited control power sources,other than trans- so that portability or relocation is impracticable. formers, shall be protected by overcurrent devices rated at 2008 Edition NATIONAL ELECTRICAL CODE 70--453 522.20 ARTICLE 522—CONTROL SYSTEMS FOR PERMANENT AMUSEMENT ATTRACTIONS not more than 125 percent of the volt-ampere rating of the Table 522,22 Conductor Ampacity Based on Copper source divided by the rated voltage.The fusible overcurrent Conductors with 60°C and 75°C Insulation in an Ambient devices shall not be interchangeable with fusible overcur Temperature of 30°C rent devices of higher ratings. The overcurrent device shall be permitted to be an integral part of the power source. Ampacity Conductor Size III. Control Circuit Wiring Methods. (AWG) 60°C 75°C 522.20 Conductors, Busbars, and Slip Rings. Insulated 30 - 0.5 control circuit conductors shall be copper and shall be per- 28 _ 0.8 mitted to be stranded or solid. Listed multiconductor cable assemblies shall be permitted. 26 - 1 Exception No. 1: Busbars and slip rings shall be permitted 24 2 2 to be materials other than copper. Exception No. 2: Conductors used as specific-purpose de- 22 3 3 vices, such as thermocouples and resistive thermal devices, 20 5 5 shall be permitted to be materials other than copper. 18 7 7 522.21 Conductor Sizing. 16 10 10 (A) Conductors Within a Listed Component or Assem- Notes: bly. Conductors of size 30 AWG or larger shall be permit- 1. For ambient temperatures other than 30°C, use Table 310.16 tem- ted within a listed component or as part of the wiring of a perature correction factors. listed assembly. 2.Ampacity adjustment for conductors with 90°C or greater insulation shall be based on ampacities in the 75°C column. (B) Conductors Within an Enclosure or Operator Sta- tion.Conductors of size 30 AWG or larger shall be permit- cuits shall be permitted to be installed with other circuits as ted in a listed and jacketed multiconductor cable within an specified in 522.24(A) and (B). enclosure or operator station. Conductors in a non-jacketed multiconductor cable, such as ribbon cable, shall not be (A) Two or More Control Circuits. Control circuits shall smaller than 26 AWG. Single conductors shall not be be permitted to occupy the same cable, cable tray, enclo- smaller than 24 AWG. sure, or raceway without regard to whether the individual circuits are alternating current or direct current,provided all Exception: Single conductors 30 AWG or larger shall be conductors are insulated for the maximum voltage of any con- permitted for jumpers and special wiring applications. ductor in the cable, cable tray, enclosure, or raceway. (C) Conductors Outside of an Enclosure or Operator (B) Control Circuits with Power Circuits. Control cir- Station. The size of conductors in a listed and jacketed, cuits shall be permitted to be installed with power conduc- multiconductor cable shall not be smaller than 26 AWG. tors as specified in 522.24($)(1) through (13)(3). Single conductors shall not be smaller than 18 AWG and shall be installed only where part of a recognized wiring (1) In a Cable, Enclosure, or Raceway. Control circuits method of Chapter 3. and power circuits shall be permitted to occupy the same cable, enclosure, or raceway only where the equipment 522.22 Conductor Ampacity. Conductors sized 16 AWG powered is functionally associated. and smaller shall not exceed the continuous current values provided in Table 522.22. (2) In Factory- or Field-Assembled Control Centers. Control circuits and power circuits shall be permitted to be 522.23 Overeurrent Protection for Conductors.Conduc- installed in factory- or field-assembled control centers. tors 30 AWG through 16 AWG shall have overcurrent pro- tection in accordance with the appropriate conductor am- (3) In a Manhole.Control circuits and power circuits shall pacity in Table 522.22. Conductors larger than 16 AWG be permitted to be installed as underground conductors in a shall have overcurrent protection in accordance with the manhole in accordance with one of the following: appropriate conductor ampacity in Table 310.16. (1) The power or control circuit conductors are in a metal- enclosed cable or Type OF cable. 522.24 Conductors of Different Circuits in the Same (2) The conductors are permanently separated from the Cable, Cable 1)ray, Enclosure, or Raceway. Control cir- power conductors by a continuous firmly fixed noncon- 70-454 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 525 CARNIVALS,CIRCUSES,FAIRS.AND SIMILAR EVENTS 525,11 ductor, such as flexible tubing, in addition to the insu- (B) Permanent Structures. Articles 518 and 520 shall ap- lation on the wire. ply to wiring in permanent structures. (3) The conductors are permanently and effectively sepa- rated from the power conductors and securely fastened (C) Audio Signal Processing,Amplification, and Repro- to racks, insulators, or other approved supports. duction Equipment. Article 640 shall apply to the wiring (4) In cable trays, where the control circuit conductors and and installation of audio signal processing, amplification, and reproduction equipment. power conductors not functionally associated with them are separated by a solid fixed barrier of a material (D) Attractions Utilizing Pools, Fountains, and Similar compatible with the cable tray, or where the power or Installations with Contained Volumes of Water. This control circuit conductors are in a metal-enclosed equipment shall be installed to comply with the applicable cable. requirements of Article 680. 522.25 Ungrounded Control Circuits. Separately derived 525,5 Overhead Conductor Clearances. ac and 2-wire do circuits and systems 50 volts or greater (A) Vertical Clearances. Conductors shall have a vertical shall be permitted to be ungrounded, provided that all the clearance to ground in accordance with 22 g 5.18. These following conditions are met: clearances shall apply only to wiring installed outside of (1) Continuity of control power is required for orderly tents and concessions. shutdown. (2) Ground detectors are installed on the control system. (B) Clearance to Portable Structures. (1) Under 600 Volts. Portable structures shall be maintained 522.28 Control Circuits in Wet Locations. Where wet not less than 4.5 m (15 ft) in any direction from overhead contact is likely to occur, ungrounded 2-wire direct-current conductors operating at 600 volts or less, except for the con- control circuits shall be limited to 30 volts maximum for ductors supplying the portable structure. Portable structures continuous do or 12.4 volts peak for direct current that is included in 525.3(D) shall comply with Table 680.8. interrupted at a rate of 10 to 200 Hz. (2) Over 600 Volts. Portable structures shall not be located under or within 4.5 m (15 ft) horizontally of conductors operating in excess of 600 volts. ARTICLE 525 525.6 Protection of Electrical Equipment. Electrical equipment and wiring methods in or on portable structures Carnivals, Circuses, Fairs, shall be provided with mechanical protection where such and Similar Events equipment or wiring methods are subject to physical damage. I. General Requirements 11. Power Sources 525.1 Scope.This article covers the installation of portable 525.10 Services. Services shall comply with 525.10(A) wiring and equipment for carnivals, circuses, fairs, and and (B). similar functions, including wiring in or on all structures. (A) Guarding. Service equipment shall not be installed in a location that is accessible to unqualified persons, unless 525.2 Definitions. the equipment is lockable. Operator.The individual responsible for starting,stopping, (B) Mounting and Location. Service equipment shall be and controlling an amusement ride or supervising a conces- mounted on solid backing and be installed so as to he pro- ston. tected from the weather, unless of weatherproof construction. Portable Structures. Units designed to be moved includ- ing, but not limited to, amusement rides, attractions, con- 525.11 Multiple Sources of Supply. Where multiple ser- vices or separately derived systems, or both, supply por- cessions, tents, trailers,trucks, and similar units. table structures, the equipment grounding conductors of all 525,3 Other Articles. the sources of supply that serve such structures separated by less than 3.7 in (12 ft) shall be bonded together at the (A) Portable Wiring and Equipment. Wherever the re- portable structures.The bonding conductor shall be copper quirements of other articles of this Code and Article 525 and Sized in accordance with Table 250.122 based on the differ, the requirements of Article 525 shall apply to the largest overcurrent device supplying the portable structures, portable wiring and equipment. but not smaller than 6 AWG. 2008 Edition NATIONAL ELECTRICAL CODE 70455 525.20 ARTICLE 525--CARNIVALS,CIRCUSES,FAIRS,AND SIMILAR EVENTS III. Wiring Methods (B) Portable Wiring Inside Tents and Concessions. Electrical wiring for lighting, where installed inside of tents 525.20 Wiring Methods. and concessions,shall be securely installed and,where sub- (A) Type. Where flexible cords or cables are used, they ject to physical damage, shall be provided with mechanical shall be listed for extra-hard usage.Where flexible cords or protection. All lamps for general illumination shall be pro- cables are used and are not subject to physical damage, tected from accidental breakage by a suitable luminaire or they shall be permitted to be listed for hard usage. Where lampholder with a guard. used outdoors, flexible cords and cables shall also be listed for wet locations and shall be sunlight resistant. Extra-hard 525.22 Portable Distribution or Termination Boxes. usage flexible cords or cables shall be permitted for use as Portable distribution or termination boxes shall comply permanent wiring on portable amusement rides and attrac- with 525.22(A) through (D). tions where not subject to physical damage. (A) Construction. Boxes shall be designed so that no live (B) Single-Conductor. Single-conductor cable shall be parts are exposed to accidental contact. Where installed permitted only in sizes 2 AWG or larger. outdoors,the box shall be of weatherproof construction and mounted so that the bottom of the enclosure is not less than (C) Open Conductors. Open conductors are prohibited 150 mm (6 in.) above the ground. except as part of a listed assembly or festoon lighting in- stalled in accordance with Article 225. (B) Busbars and Terminals. Busbars shall have an am- ( Pere rating not less than the overcurrent device supplying D) Splices. Flexible cords or cables shall be continuous the feeder supplying the box. Where conductors terminate without splice or tap between boxes or fittings. directly on busbars, bulbar connectors shall be provided. (E) Cord Connectors. Cord connectors shall not be laid (C) Receptacles and Overcurrent Protection. Recep- on the ground unless listed for wet locations. Connectors tacles shall have overcurrent protection installed within the and cable connections shall not be placed in audience traffic box. The overcurrent protection shall not exceed the am- paths or within areas accessible to the public unless pere rating of the receptacle, except as permitted in Article guarded. 430 for motor loads. (F) Support. Wiring for an amusement fide, attraction, tent, (D) Single-Pole Connectors. Where single-pole connec- or similar structure shall not be supported by any other ride or tors are used, they shall comply with 530.22. structure unless specifically designed for the purpose. (G) Protection. Flexible cords or cables accessible to the 525.23 Ground-Fault Circuit-Interrupter (GFCI) public shall be arranged to minimize the tripping hazard Protection. and shall be permitted to be covered with nonconductive (A) Where GFCI Protection Is Required, The ground- matting, provided that the matting does not constitute a fault circuit interrupter shall be permitted to be an integral greater tripping hazard than the uncovered cables. It shall part of the attachment plug or located in the power-supply be permitted to bury cables. The requirements of 300.5 cord, within 300 mm(12 in.)of the attachment plug. Listed shall not apply. cord sets incorporating ground-fault circuit interrupter for (H) Boxes and Fittings. A box or fitting shall be installed personnel shall be permitted. at each connection point, outlet, switchpoint, or junction (1) 125-volt, single-phase, 15- and 20-ampere non- point. locking-type receptacles used for disassembly and re- assembly or readily accessible to the general public 525.21 Rides, Tents, and Concessions. (2) Equipment that is readily accessible to the general pub- lic and supplied from a 125-volt, single-phase, 15- or (A) Disconnecting Means. Each portable structure shall 20-ampere branch circuit be provided with a disconnect switch located within sight of and within 1.8 m (6 ft) of the operator's station. The (B) Where GFCI Protection Is Not Required. Recep- disconnecting means shall be readily accessible to the op- tacles that only facilitate quick disconnecting and recon- erator, including when the fide is in operation. Where ac- necking of electrical equipment shall not be required to be cessible to unqualified persons, the enclosure for the switch provided with GFCI protection. These receptacles shall be or circuit breaker shall be of the lockable type.A shunt trip of the locking type. device that opens the fused disconnect or circuit breaker when a switch located in the ride operator's console is (C) Where GFCI Protection Is Not Permitted. Egress closed shall be a permissible method of opening the circuit. lighting shall not be protected by a GFCI. 70-456 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 530—MOTION PICTURE AND TELEVISION STUDIOS AND SIMILAR LOCATIONS 530.2 IV. Grounding and Bonding 530.2 Definitions. 525.30 Equipment Bonding. The following equipment Alternating-Current Power Distribution Box (Alter- connected to the same source shall be bonded: nating-Current Plugging Box,Scatter Box). An ac distri- (1) Metal raceways and metal-sheathed cable bution center or box that contains one or more grounding- (2) Metal enclosures of electrical equipment type polarized receptacles that may contain overcurrent (3) Metal frames and metal parts of portable structures, protective devices. trailers, trucks, or other equipment that contain or sup- Bull Switch. An externally operated wall-mounted safety port electrical equipment switch that may or may not contain overcurrent protection and The equipment grounding conductor of the circuit Sup- is designed for the connection of portable cables and cords. plying the equipment in items(1),(2)or(3)that is likely to Location (Shooting Location). A place outside a motion energize the metal frame or part Shall be permitted to serve picture studio where a production or part of it is filmed or as the bonding means. recorded. Location Board (Deuce Board). Portable equipment con- grounded shall be connected to an equipment grounding 525.31 Equipment Grounding. All equipment to be taining a lighting contactor or contactors and overcurrent conductor of a type recognized by 250.118 and installed in Protection designed for remote control of stage lighting. accordance with Parts VI and V11 of Article 250. The Motion Picture Studio (Lot). A building or group of equipment grounding conductor shall be Connected to the buildings and other structures designed, constructed,or per- system grounded conductor at the service disconnecting manently altered for use by the entertainment industry for means or, in the case of a separately derived system such as the purpose of motion picture or television production. a generator, at the generator or first disconnecting means supplied by the generator. The grounded circuit conductor Plugging Box. A do device consisting of one or more shall not be connected to the equipment grounding conduc- 2-Pole, 2-wire, nonpolarized, nongrounding-type recep- tor on the load side of the service disconnecting means or tacles intended to be used on do circuits only. on the load side of a separately derived system disconnect- Portable Equipment. Equipment intended to be moved ing means. from one place to another. 525.32 Grounding Conductor Continuity Assurance. Single-Pole Separable Connector. A device that is in- The continuity of the grounding conductor system used to stalled at the ends of portable, flexible, single-conductor reduce electrical shock hazards as required by 250.114, cable that is used to establish connection or disconnection 250.138,406.3(C), and 590.4(D)shall be verified each time between two cables or one cable and a single-pole, panel- that portable electrical equipment is connected, mounted separable connector. Spider(Cable Splicing Block).A device that contains bus- bars that are insulated from each other for the purpose of splicing or distributing power to portable cables and cords ARTICLE 530 that are terminated with single-pole bulbar connectors. Motion Picture and Television Studios Stage Effect (Special Effect), An electrical or electrome- and Similar Locations chanical piece of equipment used to simulate a distinctive visual or audible effect such as wind machines, lightning 1. General simulators, sunset projectors, and the like. Stage Property. An article or object used as a visual ele- 530.1 Scope.The requirements of this article shall apply to ment in a motion picture or television production, except television studios and motion picture studios using either painted backgrounds (scenery) and costumes. film or electronic cameras,except as provided in 520.1, and exchanges,factories, laboratories,stages,or a portion of the Stage Set. A specific area set up with temporary scenery building in which film or tape more than 22 mm (7/s in.) in and properties designed and arranged for a particular scene width is exposed, developed, printed, cut, edited, rewound, in a motion picture or television production. repaired, or stared. Stand Lamp (Work Light). A portable stand that contains FPN: For methods of protecting against cellulose nitrate a general-purpose luminaire or larnpholder with guard for film hazards, see NFPA 40-2007, Standard far the Storage the Purpose of providing general illumination in the studio and Handling of Cellulose Nitrate Film. or stage. 2008 Edition NATIONAL ELECTRICAL CODE 70-457 530.6 ARTICLE 530--MOTION PICTURE AND TELEVISION STUDIOS AND SIMILAR LOCATIONS Television Studio or Motion Picture Stage (Sound addition to remote-control switches.A single externally op- Stage).A building or portion of a building usually insulated erable switch shall be permitted to simultaneously discon- from the outside noise and natural light for use by the nett all the contactors on any one location board, where entertainment industry for the purpose of motion picture, located at a distance of not more than 1.8 m (6 ft) from the television, or commercial production. location board. 530.6 Portable Equipment. Portable stage and studio 530.14 Plugging Boxes. Each receptacle of do plugging lighting equipment and portable power distribution equip- boxes shall be rated at not less than 30 amperes. ment shall be permitted for temporary use outdoors if the equipment is supervised by qualified personnel while ener- 530.15 Enclosing and Guarding Live Parts. gized and barriered from the general public. (A) Live Parts. Live parts shall be enclosed or guarded to prevent accidental contact by persons and objects. II. Stage or Set (B) Switches. All switches shall be of the externally oper- 530.11 Permanent Wiring.The permanent wiring shall be able type. Type MC cable, Type AC cable containing an insulated equipment grounding conductor sized in accordance with (C) Rheostats.Rheostats shall be placed in approved cases Table 250.122, Type MI cable, or in approved raceways. or cabinets that enclose all live parts, having only the op- Exception: Communications circuits;audio signal process erating handles exposed. ing, amplification, and reproduction circuits; Class 1, Class (D) Current-Carrying Parts. Current-carrying parts of 2, and Class 3 remote-control or signaling circuits and bull switches, location boards, spiders, and plugging boxes power-limited fire alarm circuits shall be permitted to be shall be enclosed, guarded, or located so that persons can- wired in accordance with Articles 640, 725, 760, and 800. not accidentally come into contact with them or bring con- ductive material into contact with them. 530.12 Portable Wiring. (A) Stage Set Wiring. The wiring for stage set lighting 530.16 Portable Luminaires.Portable luminaires and work and other supply wiring not fixed as to location shall be lights shall be equipped with flexible cords, composition or done with listed hard usage flexible cords and cables. metal-sheathed porcelain sockets, and substantial guards. Where subject to physical damage, such wiring shall be Exception: Portable luminaires used as properties in a mo- ]isted extra-hard usage flexible cards and cables. Splices or tion picture set or television stage set, on a studio stage or taps in cables shall be permitted if the total connected load lot, or on location shall not be considered to be portable does not exceed the maximum ampacity of the cable, luminaires for the purpose of this section. (B) Stage Effects and Electrical Equipment Used as 530.17 Portable Are Lamps. Stage Properties. The wiring for stage effects and electri- cal equipment used as stage properties shall be permitted to (A) Portable Carbon Arc Lamps. Portable carbon arc be wired with single-or multiconductor listed flexible cords lamps shall be substantially constructed. The arc shall be or cables if the conductors are protected from physical provided with an enclosure designed to retain sparks and damage and secured to the scenery by approved cable ties carbons and to prevent persons or materials from coming or by insulated staples. Splices or taps shall be permitted into contact with the arc or bare live parts. The enclosures where such are made with listed devices and the circuit is shall be ventilated. All switches shall be of the externally protected at not more than 20 amperes. operable type. (C) Other Electrical Equipment. Cords and cables other (B) Portable Noncarbon Are Electric-Discharge Lamps. than extra-hard usage, where supplied as a part of a listed Portable noncarbon arc lamps, including enclosed are assembly, shall be permitted. lamps, and associated ballasts shall be listed. Interconnect- ing cord sets and interconnecting cords and cables shall be 530.13 Stage Lighting and Effects Control. Switches extra-hard usage type and listed. used for studio stage set lighting and effects (on the stages and lots and on location) shall be of the externally operable 530.18 Overcurrent Protection — General. Automatic type.Where contactors are used as the disconnecting means overcurrent protective devices (circuit breakers or fuses) for fuses, an individual externally operable switch,Suitably for motion picture studio stage set lighting and the stage rated, for the control of each contactor shall be located at a cables for such stage set lighting shall be as given in distance of not more than 1.8 m(6 ft)from the contactor, in 530.18(A) through (G). The maximum ampacity allowed 70-458 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 530—MOTION PICTURE AND TELEVISION STUDIOS AND SIMILAR LOCATIONS 530.21 on a given conductor, cable, or cord size shall be as given boxes shall be by means Of plugs containing two cartridge in the applicable tables of Articles 310 and 400. fuses not larger than 20 amperes, or they shall be permitted to be connected to special outlets on circuits protected by (A) Stage Cables. Stage cables for stage set lighting shall fuses or circuit breakers rated at not over 20 amperes. Plug be protected by means of overcurrent devices set at not fuses shall not be used unless they are on the load side of more than 400 percent of the ampacity given in the appli- the fuse or circuit breakers on the location boards. cable tables of Articles 310 and 400. (B) Feeders. In buildings used primarily for motion pic- 530.19 Sizing of Feeder Conductors for Television Stu- ture production, the feeders from the substations to the dio Sets. stages shall be protected by means of overcurrent devices (generally located in the substation) having a suitable am- {A) General. It shall be permissible to apply the demand factors listed in Table 530.19(A) to that portion of the pere rating. The overcurrent devices shall be permitted to maximum possible connected load for studio or stage set be multipole or single-pole gang operated. No pole shall be lighting for all permanently installed feeders between sub- required in the neutral conductor. The overcurrent device stations and stages and to all permanently installed feeders setting for each feeder shall not exceed 400 percent of the between the main stage switchboard and stage distribution ampacity of the feeder, as given in the applicable tables of centers or location boards. Article 310. (C) Cable Protection. Cables shall be protected by bush- (B) Portable Feeders. A demand factor of 50 percent of ings where they pass through enclosures and shall be ar- maximum possible connected load shall be permitted for all ranged so that tension on the cable is not transmitted to the Portable feeders. connections. Where power conductors pass through metal, Table 530.19(A) Demand Factors for Stage Set Lighting the requirements of 300.20 shall apply. Portable feeder cables shall be permitted to temporarily Portion of Stage Set Lighting Load Feeder Demand penetrate fire-rated walls, floors, or ceilings provided that to Which Demand Factor Applied Factor all of the following apply: (volt-amperes) M (1) The opening is of noncombustible material. First 50,000 or less at 100 (2) When in use,the penetration is sealed with a temporary From 50,001 to 100,000 at 75 seal of a listed firestop material. From 100,001 to 200,000 at 60 (3) When not in use, the opening shall be capped with a Remaining over 200,000 at 50 material of equivalent fire rating. (D) Location Boards.Overcurrent protection(fuses or cir- 530.20 Grounding. Type MC cable,Type Ml cable, metal cuit breakers) shall be provided at the location boards. raceways, and all non—current-carrying metal parts of ap- pliances,in the location boards shall have an ampere rating of pliances, devices, and equipment shall be connected to an not over 400 percent of the ampacity of the cables between equipment grounding conductor. This shall not apply to pendant and portable lamps, to stage lighting and stage the location boards and the plugging boxes. sound equipment, or to other portable and special stage (E) Plugging Boxes. Cables and cords supplied through equipment operating at not over 150 volts do to ground. plugging boxes shall be of copper. Cables and cords smaller than 8 AWG shall be attached to the plugging box by means 530.21 Plugs and Receptacles. of a plug containing two cartridge fuses or a 2-pole circuit breaker. The rating of the fuses or the setting of the circuit (A) Rating. Plugs and receptacles shall be rated in am- breaker. shall not be over 400 percent of the rated ampacity peres. The voltage rating of the plugs and receptacles shall of the cables or cords as given in the applicable tables of be not less than the circuit voltage. Plug and receptacle Articles 3 10 and 400.Plugging boxes shall not be permitted ampere ratings For ac circuits shall not be less than the feeder or branch-circuit overcurrent device ampere rating. on ac systems. Table 210.21(B)(2) shall not apply. (F) Alternating-Current Power Distribution Boxes. Alternating-current power distribution boxes used on sound (B) Interchangeability. Plugs and receptacles used in por- stages and shooting locations shall contain connection re- table professional motion picture and television equipment ceptacles of a polarized, grounding type. shall be permitted to be interchangeable for ac or do use on the same premises, provided they are listed for ac/dc use (G) Lighting. Work lights, stand lamps, and luminaires and marked in a suitable manner to identify the system to rated 1000 watts or less and connected to do plugging which they are connected. 2008 Fdition NATIONAL ELECTRICAL CODE 701159 530.22 ARTICLE 530—MOTION PICTURE AND TELEVISION STUDIOS AND SIMILAR LOCATIONS 530.22 Single-Pole Separable Connectors. suitable means to guard lamps from physical damage and (A) General. Where ac single-pole portable cable connec- from film and film scrap shall be used at patching, viewing, tors are used, they shall be listed and of the locking type. and cutting tables. Sections 400.10, 406.6, and 406.7 shall not apply to listed single-pole separable connections and single-conductor V. Cellulose Nitrate Film Storage Vaults cable assemblies utilizing listed single-pole separable con- nectors. Where paralleled sets of current-carrying single- 530.51 Lamps in Cellulose Nitrate Film Storage Vaults, pole separable connectors are provided as input devices, Lamps in cellulose nitrate film storage vaults shall be in- they shall be prominently labeled with a warning indicating stalled in rigid fixtures of the glass-enclosed and gasketed the presence of internal parallel connections. The use of type. Lamps shall be controlled by a switch having a pole single-pole separable connectors shall comply with at least in each ungrounded conductor. This switch shall be located one of the following conditions: outside of the vault and provided with a pilot light to indi- (1) Connection and disconnection of connectors are only cate whether the switch is on or off. This switch shall dis- possible where the supply connectors are interlocked to connect from all sources of supply all ungrounded conduc- the source and it is not possible to connect or discon- tors terminating in any outlet in the vault. nect connectors when the supply is energized. (2) Line connectors are of the listed sequential-interlocking 530.52 Electrical Equipment in Cellulose Nitrate Film type so that load connectors shall be connected in the Storage Vaults. Except as permitted in 530.51, no recep- following sequence: tables, outlets, heaters, portable lights, or other portable a. Equipment grounding conductor connection electrical equipment shall be located in cellulose nitrate b. Grounded circuit conductor connection, if provided film storage vaults. Electric motors shall be permitted, pro- c. Ungrounded conductor connection, and that discon- vided they are listed for the application and comply with nection shall be in the reverse order Article 500, Class I, Division 2. (3) A caution notice shall be provided adjacent to the line connectors, indicating that plug connection shall be in VI. Substations the following order: a. Equipment grounding conductor connectors 530.61 Substations. Wiring and equipment of over 600 b. Grounded circuit-conductor connectors, if provided volts, nominal, shall comply with Article 490. c. Ungrounded conductor connectors, and that discon- nection shall be in the reverse order 530.62 Portable Substations. Wiring and equipment in portable substations shall conform to the sections applying (B) Interchangeability. Single-pole separable connectors to installations in permanently fixed substations, but,due to used in portable professional motion picture and television the limited space available, the working spaces shall be equipment shall be permitted to be interchangeable for ac permitted to be reduced, provided that the equipment shall or do use or for different current ratings on the same pre- be arranged so that the operator can work safely and so that mises, provided they are listed for ac/dc use and marked in a suitable manner to identify the system to which they are other persons in the vicinity cannot accidentally come into connected. contact with current-carrying parts or bring conducting ob- jects into contact with them while they are energized. 530.23 Branch Circuits. A branch circuit of any size sup- plying one or more receptacles shall be permitted to supply 530.63 Overcurrent Protection of Direct-Current Gen- stage set lighting loads. erators. 'three-wire generators shall have overcurrent pro- tection in accordance with 445.12(E). III. Dressing Rooms 530.64 Direct-Current Switchboards. 530.31 Dressing Rooms. Fixed wiring in dressing rooms shall be installed in accordance with the wiring methods (A) General. Switchboards of not over 250 volts do be- covered in Chapter 3. Wiring for portable dressing rooms tween conductors, where located in substations or switch- shall be approved. board rooms accessible to qualified persons only, shall not be required to be dead-front. IV. Viewing, Cutting, and Patching Tables (B) Circuit Breaker Frames. Frames of do circuit break- 530.41 Lamps at Tables. Only composition or metal- ers installed on switchboards shall not be required to be sheathed, porcelain, keyless lampholders equipped with connected to an equipment grounding conductor. 70-460 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 540—MOTION PICTURE PROJECTION ROOMS 540,12 of motor generator sets shall comply with one of the con- ARTICLE 540 ditions in 540.11(A)(1) through (A)(6). Motion Picture Projection Rooms (1) Types. Be of the totally enclosed, enclosed fan-cooled, or enclosed pipe-ventilated type. I. General (2) Separate Rooms or Housings. Be enclosed in separate rooms or housings built of noncombustible material con- structed so as 540.1 Scope.The provisions of this article apply to motion to exclude flyings or lint, and properly ven- picture projection rooms, motion picture projectors, and as- struct from s source of clean air. sociated equipment of the professional and nonprofessional types using incandescent, carbon arc, xenon, or other light (3) Solid Metal Covers. Have the brush or sliding-contact source equipment that develops hazardous gases, dust, or end of motor-generator enclosed by solid metal covers. radiation. (4) Tight Metal Housings. Have brushes or sliding con- FPN: For further information, see NFPA 40-2007, Stan- tact-, enclosed in substantial, tight metal housings. dard for the Storage and Handling of Cellulose Nitrate Film. ($) Upper and Lower Half Enclosures. Have the upper half of the brush or sliding-contact end of the motor- 540.2 Definitions. generator enclosed by a wire screen or perforated metal and the lower half enclosed by solid metal covers. Nonprofessional Projector.Nonprofessional projectors are those types other than as described in 540.2. (6) Wire Screens or Perforated Metal.Have wire screens or perforated metal placed at the commutator of brush ends. Professional Projector. A type of projector using 35- or No dimension of any opening in the wire screen or perfo- 70-mm film that has a minimum width of 35 mm (1'/s in.) rated metal shall exceed 1.27 mm (0.05 in.), regardless of and has on each edge 212 perforations per meter (5.4 per- the shape of the opening and of the material used. forations per inch), or a type using carbon arc, xenon, or Equip- other light source equipment that develops hazardous gases, (B} ,Switches, Overcurrent Devices, or Other Equip- ment. Switches, overcurrent devices, or other equipment dust, or radiation. not normally required or used for projectors, sound repro- duction, flood or other special effect lamps, or other equip- II. Equipment and Projectors of the Professional Type ment shall not be installed in projection rooms. 540.10 Motion Picture Projection Room Required. Ev- Exception No. 1: In projection rooms approved for use ery professional-type projector shall be located within a only with cellulose acetate (safety)film, the installation of projection room, Every projection roam shall be of perma- appurtenant electrical equipment used in conjunction with nent construction, approved for the type of building in the operation of the projection equipment and the control of which the projection room is located. All projection ports, lights, curtains, and audio equipment, and so forth, shall be spotlight ports, viewing ports, and similar openings shall be permitted. In such projection rooms, a sign reading "Safety provided with glass or other approved material so as to Film Only Permitted in This Room" shall be posted on the completely close the opening. Such rooms shall not be con- outside of each projection room door and within the pro- sidered as hazardous (classified) locations as defined in Ar- jection room itself in a conspicuous location. ticle 500. Exception No. 2: Remote-control switches for the control FPN: For further information on protecting openings of auditorium lights or switches for the control of motors re operating curtains and masking of the motion picture projection roams handling cellulose nitrate motion picture film, see NFPA 101-2006, Life Safety Code. screen shall be permitted to be installed in projection rooms. 540.11 Location of Associated Electrical Equipment. (C) Emergency Systems. Control of emergency systems (A) Motor Generator Sets, Transformers, Rectifiers, shall comply with Article 700. Rheostats, and Similar Equipment. Motor-generator sets, transformers,rectifiers,rheostats, and similar equipment for 540.12 Work Space. Each motion picture projector, flood- light, spotlight, or similar equipment shall have clear work- the supply or control of current to projection or spotlight equipment shall, where nitrate film is used, be located in a ing space not less than 750 mm (30 in.) wide on each side and at the rear thereof. separate room. Where placed in the projection room, they shall be located or guarded so that arcs or sparks cannot Exception: One such space shall be permitted between ad- come in contact with film, and the commutator end or ends jacent pieces of equipment. 2009 Edition NATIONAL ELECTRICAL CODE 70-461 540.13 ARTICLE 545—MANUFACTURED BUILDINGS 540.13 Conductor Size. Conductors supplying outlets for Building Component. Any subsystem, subassembly, or arc and xenon projectors of the professional type shall not other system designed for use in or integral with or as part be smaller than 8 AWG and shall have an ampaeity not less of a structure, which can include structural, electrical, ure- than the projector current rating. Conductors for chanical, plumbing, and fire protection systems, and other incandescent-type projectors shall conform to normal wir- systems affecting health and safety, ing standards as provided in 210.24. Building System, Plans, specifications, and documentation 540.14 Conductors on Lamps and Hot Equipment. In- for a system of manufactured building or for a type or a sulated conductors having a rated operating temperature of system of building components, which can include struc- not less than 200°C (392°F) shall be used on all lamps or tural, electrical, mechanical, plumbing, and fire protection other equipment where the ambient temperature at the con- systems, and other systems affecting health and safety, and ductors as installed will exceed 50°C (122°F) including such variations thereof as are specifically permit- ted by regulation, and which variations are submitted as 540.15 Flexible Cords. Cords approved for hard usage, as part of the building system or amendment thereto. provided in Table 400.4,shall be used on portable equipment. Closed Construction. Any building, building component, assembly,or system manufactured in such a manner that all 540.20 Listing Requirements. Projectors and enclosures concealed parts of processes of manufacture cannot be in- for arc, xenon, and incandescent lamps and rectifiers, trans- spected before installation at the building site without dis- formers, rheostats, and similar equipment shall be listed. assembly, damage, or destruction. 540.21 Marking. Projectors and other equipment shall be Manufactured Building. Any building that is of closed marked with the manufacturer's name or trademark and construction and is made or assembled in manufacturing with the voltage and current for which they are designed in facilities on or off the building site for installation, or for accordance with 110.21. assembly and installation on the building site, other than manufactured homes, mobile homes, park trailers, or recre- ational vehicles. III. Nonprofessional Projectors 540.31 Motion Picture Projection Room Not Required. 545.4 Wiring Methods. Projectors of the nonprofessional or miniature type, where (A) Methods Permitted. All raceway and cable wiring employing cellulose acetate(safety) film,shall be permitted methods included in this Code and such other wiring to be operated without a projection room. systems specifically intended and listed for use in manu- factured buildings shall be permitted with listed fittings 540.32 Listing Requirements. Projection equipment shall and with fittings listed and identified for manufactured be listed. buildings. IV. Audio Signal Processing, Amplification, and (B) Securing Cables. In closed construction, cables shall Reproduction Equipment be permitted to be secured only at cabinets, boxes, or fit- tings where 10 AWG or smaller conductors are used and 540.50 Audio Signal Processing,Amplification, and Re- protection against physical damage is provided. production Equipment. Audio signal processing, amplifi- cation, and reproduction equipment shall be installed as 545.5 Supply Conductors. Provisions shall be made to provided in Article 640. route the service-entrance, service-lateral, feeder, or branch-circuit supply to the service or building disconnect- ing means conductors. 545.6 Installation of Service-Entrance Conductors. ARTICLE 545 Service-entrance conductors shall be installed after erection Manufactured Buildings at the building site. Exception: Where point of attachment is known prior to 545.1 Scope.This article covers requirements for a manufac- manufacture. tured building and building components as herein defined. 545.7 Service Equipment. Service equipment shall be in- 545.2 Definitions. stalled in accordance with 230.70. 70-462 NATIONAL,ELECTRICAL CODE 2009 Edition ARTICLE 547—AGRICULTURAL BUILDINGS S47.5 545.8 Protection of Conductors and Equipment. Protec- (A) Excessive Dust and Dust with Water. Agricultural tion shall be provided for exposed conductors and equip- buildings where excessive dust and dust with water may ment during processes of manufacturing, packaging, in accumulate, including all areas of poultry, livestock, and transit, and erection at the building site, fish confinement systems, where litter dust or feed dust, including mineral feed particles, may accumulate. 545.9 Boxes. (B) Corrosive Atmosphere. Agricultural buildings where (A) Other Dimensions. Boxes of dimensions other than a corrosive atmosphere exists. Such buildings include areas those required in Table 314.16(A) shall be permitted to be where the following conditions exist: installed where tested, identified, and listed to applicable (1) Poultry and animal excrement may cause corrosive va- standards. pars. (B) Not Over 1650 em3 (100 in.3). Any box not over (2) Corrosive particles may combine with water. 1650 Cm; (100 in.3) in size, intended for mounting in (3) The area is damp and wet by reason of periodic wash- closed construction, shall be affixed with anchors or clamps ing for cleaning and sanitizing with water and cleans- so as to provide a rigid and secure installation. ing agents. (4) Similar conditions exist. 54510 Receptacle or Switch with Integral Enclosure. A receptacle or switch with integral enclosure and mounting 547.2 Definitions. means, where tested, identified, and listed to applicable Distribution Point. An electrical supply point from which standards, shall be permitted to be installed. service drops, service conductors, feeders, or branch cir- cuits to buildings or structures utilized under single man- 545.11 Bonding and Grounding. Prewired panels and agement are supplied. building components shall provide for the bonding, or bonding and grounding, of all exposed metals likely to be- FPN No. l: Distribution points are also known as the cen- come energized, in accordance with Article 250, Parts V, ter yard pole, meterpole, or the common distribution point. VI, and VII. FPN No. 2: The service point as defined in Article 100 is typically at the distribution point. 545.12 Grounding Electrode Conductor.Provisions shall Equipotential Plane. An area where wire mesh or other be made to route a grounding electrode conductor from the conductive elements are embedded in or placed under con- service, feeder, or branch-circuit supply to the point of at- crete, bonded to all metal structures and fixed nonelectrical tachment to the grounding electrode, equipment that may become energized, and connected to the electrical grounding system to prevent a difference in 545.13 Component interconnections. Fittings and con- voltage from developing within the plane. nectors that are intended to be concealed at the time of Site-Isolating Device. A disconnecting means installed at on-site assembly, where tested, identified, and listed to ap- plicable standards, shall be permitted for on-site intercon- the distribution point for the purposes of isolation, system nection of modules or other building components. Such maintenance, emergency disconnection, or connection of fittings and connectors shall be equal to the wiring method optional standby systems. employed in insulation, temperature rise, and fault-current 547.3 Other Articles. For buildings and structures not withstand and shall be capable of enduring the vibration having conditions as specified in 547.1,the electrical instal- and minor relative motions occurring in the components of lations shall be made in accordance with the applicable manufactured buildings. articles in this Code. 547.4 Surface Temperatures. Electrical equipment or de- vices installed in accordance with the provisions of this ARTICLE 547 article shall be installed in a manner such that they will function at full rating without developing surface tempera- tures in excess of the specified normal safe operating range of the equipment or device. 547.1 Scope. The provisions of this article shall apply to 547.5 Wiring Methods. the following agricultural buildings or that part of a build- ing or adjacent areas of similar or like nature as specified in (A) Wiring Systems. Types UF, NMC, copper SE cables, 547.1(A) and (B). jacketed Type MC cable,rigid nonmetallic conduit, liquidtight 2008 Edition NATIONAL ELECTRICAL CODE 70-463 547.6 ARTICLE 547—AGRICULTURAL BUILDINGS flexible nonmetallic conduit,or other cables or raceways suit- cation falling under the scope of Article 547, it shall be a able for the location, with approved termination fittings,shall copper conductor.Where an equipment grounding conduc- be the wiring methods employed.The wiring methods of Ar- for is installed underground,it shall be insulated or covered ticle 502, Part II, shall be permitted for areas described in copper. 547.1(A). (G) Receptacles. All 125-volt, single-phase, 15- and 20- FPN: See 300.7, 352.44, and 355.44 for installation of ampere general-purpose receptacles installed in the loca- raceway systems exposed to widely different temperatures. tions listed in (1) through (4) shall have ground-fault (B) Mounting. All cables shall be secured within 200 mm circuit-interrupter protection: (8 in,) of each cabinet, box, or fitting, Nonmetallic boxes, (1) Areas having an equipotential plane fittings, conduit, and cables shall be permitted to be (2) Outdoors mounted directly to any building surface covered by this (3) Damp or wet locations article without maintaining the 6 mm (tft in.) airspace in (4) Dirt confinement areas for livestock accordance with 300.6(D). GFCI protection shall not be required for an accessible (C) Equipment Enclosures, Boxes, Conduit Bodies, and receptacle supplying a dedicated load where a GFCI pro- Fittings. tected receptacle is located within 900 mm (3 ft) of the (1) Excessive Dust. Equipment enclosures, boxes, conduit non-GFCI-protected receptacle. bodies, and fittings installed in areas of buildings where Control- excessive dust may be present shall be designed to mini- $47.6 Switches, Receptacles, Circuit Breakers, Control- mize the entrance of dust and shall have no openings (such lets, and Fuses. Switches, including pushbuttons, relays, as holes for attachment screws) through which dust could and similar devices, receptacles, circuit breakers, control- enter the enclosure. lers, and fuses, shall be provided with enclosures as speci- fied in 547.5(C). (2) Damp or Wet Locations. In damp or wet locations, equipment enclosures, boxes, conduit bodies, and fittings 547.7 Motors. Motors and other rotating electrical ma- shall be placed or equipped so as to prevent moisture from chinery shall be totally enclosed or designed so as to mini- entering or accumulating within the enclosure, box, conduit mize the entrance of dust, moisture, or corrosive particles. body, or fitting. In wet locations, including normally dry or damp locations where surfaces are periodically washed or 547.8 Luminaires. Luminaires shall comply with 547.8(A) sprayed with water, boxes,conduit bodies,and fittings shall through (C). be listed for use in wet locations and equipment enclosures (A) Minimize the Entrance of Dust. Luminaires shall be shall be weatherproof. installed to minimize the entrance of dust, foreign matter, (3) Corrosive Atmosphere. Where wet dust, excessive moisture, and corrosive material. moisture, corrosive gases or vapors, or other corrosive con- ditions may be present, equipment enclosures, boxes, con- (B) Exposed to Physical Damage. Luminaires exposed to duit bodies, and fittings shall have corrosion resistance physical damage shall be protected by a suitable guard. properties suitable for the conditions. (C) Exposed to Water. Luminaires exposed to water from FPN No. l: See Table 110.20 For appropriate enclosure condensation, building cleansing water, or solution shall be type designations. watertight. FPN No.2: Aluminum and magnetic Ferrous materials may corrode in agricultural environments. 547.9 Electrical Supply to Building(s) or Structure(s) from a Distribution Point. A distribution point shall be (D) Flexible Connections. Where necessary to employ permitted to supply any building or structure located on the flexible connections, dusttight flexible connectors, liq- same premises. The overhead electrical supply shall comply uidtight flexible metal conduit, liquidtaight flexible nonme- with 547.9(A) and (B), or with 547.9(C). The underground tallic conduit, or flexible cord listed and identified for hard electrical supply shall comply with 547.9(C) and (D). usage shall be used. All connectors and fittings used shall be listed and identified for the purpose. (A) Site-isolating Device. Site-isolating devices shall comply with 547.9(A)(1) through (A)(10). (E) Physical Protection. All electrical wiring and equip- ment subject to physical damage shall be protected. (1) Where Required. Asite-isolating device shall be in- stalled at the distribution point where two or more agricul- (F) Separate Equipment Grounding Conductor. Where turai buildings or structures are supplied from the distribu- an equipment grounding conductor is installed within a lo- tion point. 70-464 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 547—AGRICULTURAL BUILDINGS 547.14 (2) Location. The site-isolating device shall be pole- is adjusted in size in accordance with the equivalent mounted and shall meet the clearance requirements of size columns of Table 250.122 if of different materials. 230.24. (2) The equipment grounding conductor is connected to (3) Operation. The site-isolating device shall simulta- the grounded circuit conductor and the site-isolating neously disconnect all ungrounded service conductors from device at the distribution point. the premises wiring. (C) Service Disconnecting Means and Overcurrent Pro- (4) Bonding Provisions. The site-isolating device enclo- tection at the Distribution Point. Where the service dis- sure shall be connected to the grounded circuit conductor connecting means and overcurrent protection for each set of and the grounding electrode system. feeder conductors are located at the distribution point,feed- ers to building(s)or structure(s)shall meet the requirements (5) Grounding. At the site-isolating device, the system of 250.32 and Article 225, Parts I and 11. grounded conductor shall be connected to a grounding elec- trode system via a grounding electrode conductor. FPN: Methods to reduce neutral-to-earth voltages in live- stock Facilities include supplying buildings or structures (6) Rating. The site-isolating device shall be rated for the with 4-wire single-phase services, sizing 3-wire single- phase service and feeder conductors to limit voltage drop to calculated load as determined by Part V of Article 220. 2 percent, and connecting loads line-to-line. (7) Overcurrent Protection. The site-isolating device shall not be required to provide overcurrent protection. (D) Direct-Buried Equipment Grounding Conductors. Where livestock is housed, any portion of a direct-buried (8) Accessibility. Where the site-isolating device is not equipment grounding conductor run to the building or readily accessible, it shall be capable of being remotely structure shall be insulated or covered copper. operated by an operating handle installed at a readily ac- cessible location. The operating handle of the site-isolating {E) ldentiification. Where a site is supplied by more than device, when in its highest position, shall not be more than one service with any two services located a distance Of 2.Q m (6 ft 7 in.) abovegrade or a working platform. 150 m (500 ft) Or less apart, as measured in a straight line, a permanent plaque or directory shall be installed at each of (9) Series Devices. An additional site-isolating device for these distribution points denoting the location of each of the premises wiring system shall not be required where a the other distribution points and the buildings or structures site-isolating device meeting all applicable requirements of served by each. this section is provided by the serving utility as part of their service requirements. 547.10 Equipotential Planes and Bonding of Equipoten- tial Planes. The installation and bonding of equipotential (10) Marking.A site-isolating device shall be permanently planes shall comply with 547.10(A) and (B). For the pur- marked to identify it as a site-isolating device. This mark poses of this section, the term livestock shall not include ing shall be located on the operating handle or immediately poultry. adjacent thereto. (A) Where Required. Equipotential planes shall be in- (B) Service Disconnecting Means and Overcurrent Pro- stalled where required in (A)(1) and(A)(2). tection at the Building(s) or Structure(s). Where the ser- vice disconnecting means and overcurrent protection are (1) Indoors.Equipotential planes shall be installed in con- located at the building(s) or structure(s), the requirements finement areas with concrete floors where metallic equip- of 547.9(B)(1) through (13)(3) shall apply, ment is located that may become energized and is acces- sible to livestock. (1) Conductor Sizing. The supply conductors shall be sized in accordance with Part V of Article 220. (2) Outdoors. Equipotential Blanes shall be installed in concrete Slabs where metallic equipment is located that (2) Conductor Installation. The supply conductors shall may become energized and'is accessible to livestock. be installed in accordance with the requirements of Part II The equipotential plane shall encompass the area where of Article 225. the livestock stands while accessing metallic equipment (3) Grounding and Bonding. For each building or struc- that may become energized. ture, grounding and bonding of the supply conductors shall (B) Bonding. Equipotential planes shall be connected to be in accordance with the requirements of 250.32, and the the electrical grounding system. The bonding conductor following conditions shall be met: shall be copper, insulated, covered or bare, and not smaller (1) The equipment grounding conductor is the same size as than 8 AWG. The means of bonding to wire mesh or con- the largest supply conductor if of the same material, or ductive elements shall be by pressure connectors or clamps 2009 Edition NATIONAL ELECTRICAL CODE 70-465 550.1 ARTICLE 5511—MOBILE HOMES,MANUFACTURED HOMES,AND MOBILE HOME PARKS of brass, copper, copper alloy, or an equally substantial Distribution Panelboard. See definition of panelboard in approved means. Slatted floors that are supported by struc- Article 100. tures that are a part of an equipotential plane shall not Feeder Assembly. The overhead or under-chassis feeder require bonding. conductors, including the grounding conductor, together FPN No. 1: Methods to establish equipotential planes are with the necessary fittings and equipment or a power- described in American Society or Agricultural and Biologi- supply cord listed for mobile home use, designed for the cal Engineers (ASABE) EP473.2-2001, Equipotential purpose of delivering energy from the source of electrical Planes in Animal Containment Areas. supply to the distribution panelboard within the mobile FPN No. 2: Methods for safe installation of livestock wa- home. terers are described in American Society of Agricultural and Biological Engineers (ASABE) EP342.2-1995, Safety Laundry Area.An area containing or designed to contain a far Electrically Heated Livestock Waterers. laundry tray, clothes washer, or a clothes dryer. FPN No. 3: Low grounding electrode system resistances Manufactured Home. A structure, transportable in one or may reduce potential ditlerences in livestock facilities, more sections,that,in the traveling mode, is 2.4 m(8 body- ft) or more in width or 12.2 m (40 body-ft) or more in length, or, when erected on site, is 29.7 m` (320 ft`) or more and that is built on a permanent chassis and designed ARTICLE 550 to be used as a dwelling, with or without a permanent foundation, when connected therein. The term ma ucfac- Mobile Homes, Manufactured Homes, Lured home includes any structure that meets all the provi- and Mobile Home Parks sions of this paragraph except the size requirements and with respect to which the manufacturer voluntarily files a certification required by the regulatory agency, and except I, General that such term does not include any self-propelled recre- 550.1 Scope. The provisions of this article cover the elec- ational vehicle. Calculations used to determine the number trical conductors and equipment installed within or on mo- of square meters (square feet) in a structure are based on bile and manufactured homes, the conductors that connect the structure's exterior dimensions, measured at the largest mobile and manufactured homes to a supply of electricity, horizontal projections when erected on site. These dimen- and the installation of electrical wiring, luminaires, equip- sions include all expandable rooms,cabinets,and other pro- ment, and appurtenances related to electrical installations jections containing interior space but do not include bay within a mobile home park up to the mobile home service- windows. entrance conductors or, if none, the mobile home service For the purpose of this Code and unless otherwise in- equipment. dicated, the term mobile home includes manufactured homes. FPN: For additional information on manufactured housing see NFPA 501-2005, Standard on Manty'rtctured Housing, FPN No. 1: See the applicable building code for definition and Part 3280, Manufactured Home Construction and of the term permanent foundation. Safety Standards, of the Federal Department of Housing FPN No.2: See Part 3280,Manufactured Home Construc- and Urban Development. tion and Safety Standards, of the Federal Department of Housing and Urban Development, for additional informa- 550.2 Definitions. tion on the definition. Appliance, Fixed. An appliance that is fastened or other- Mobile Home. A factory-assembled structure or structures wise secured at a specific location. transportable in one or more sections that are built on a permanent chassis and designed to be used as a dwelling Appliance, Portable. An appliance that is actually without a permanent foundation where connected to the moved or can easily be moved from one place to another required utilities and that include the plumbing, heating, in normal use. air-conditioning, and electrical systems contained therein. For the purpose of this Cade and unless otherwise in- FPN: For the purpose of this article, the following major dicated, the term mobile home includes manufactured appliances, other than built-in, are considered portable if cord connected: refrigerators, range equipment, clothes homes. washers, dishwashers without booster heaters, or other similar appliances. Mobile Home Accessory Building or Structure. Any aw- ning, cabana, ramada, storage cabinet,carport, fence, wind- Appliance, Stationary. An appliance that is not easily break, or porch established for the use of the occupant of moved from one place to another in normal use. the mobile home on a mobile home lot. 70-466 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 550—MOBILE HOMES,MANUFACTURED HOMES,AND MOBILE HOME PARKS 550.10 Mobile Home Lot. A designated portion of a mobile home grally molded or securely attached plug cap or a perma- park designed for the accommodation of one mobile home nently installed feeder. and its accessory buildings or structures for the exclusive Exception No. 1: A mobile home that is factori equipped use of its occupants. with gas or oil fired central heating equipment and cooking Mobile Home Park. A contiguous parcel of land that is appliances shall be permitted to be provided with a listed used for the accommodation of occupied mobile homes. mobile home power-supply cord rated 40 amperes. Exception No. 2: A feeder assembly shall not be required Mobile Home Service Equipment, The equipment con- taining manufactured the disconnecting means, overcurrent protective de- 550.32(B).u vices, and receptacles or other means for connecting a mo- bile home feeder assembly. (B) Power-Supply Cord. If the mobile home has a power- supply cord, it shall be permanently attached to the distri- Park Electrical Wiring Systems. All of the electrical wir- bution panelboard or to a junction box permanently con- ing, luminaires, equipment, and appurtenances related to nected to the distribution panelboard, with the free end electrical installations within a mobile home park, includ- terminating in an attachment plug cap. ing the mobile home service equipment. Cords with adapters and pigtail ends, extension cords, and similar items shall not be attached to, or shipped with, 550.4 General Requirements. a mobile home. A suitable clamp or the equivalent shall be provided at (A} Mobile Home Not Intended as a Dwelling Unit. A mobile home not intended as a dwelling unit — for ex- the distribution panelboard knockout to afford strain relief ample, those equipped for sleeping purposes only, contrac- for the cord to prevent strain from being transmitted to the tor's on-site offices, construction job dormitories, mobile terminals when the power-supply cord is handled in its studio dressing rooms, banks, clinics, mobile stores, or in- intended manner. tended for the display or demonstration of merchandise or The cord shall be a listed type with four conductors, machinery — shalI not be required to meet the provisions one of which shall be identified by a continuous green color of this article pertaining to the number or capacity of cir- or a continuous green color with one or more yellow stripes cuits required. It shall, however, meet all other applicable for use as the grounding conductor. requirements of this article if provided with an electrical (C) Attachment Plug Cap. The attachment plug cap shall installation intended to be energized from a 120-volt or be a 3-pole, 4-wire, grounding type, rated 50 amperes, 1201240-volt ac power supply system.Where different volt- 1251250 volts with a configuration as shown in Figure age is required by either design or available power supply 550.10(C) and intended for use with the 50-ampere, 1251250- system, adjustment shall be made in accordance with other volt receptacle configuration shown in Figure 550.10(0). It articles and sections for the voltage used. shall be listed, by itself or as part of a power-supply cord assembly, for the purpose and shall be molded to or installed (B) In Other Than Mobile Home Parks. Mobile homes on the flexible cord so that it is secured tightly to the cord at installed in other than mobile home parks shall comply the point where the cord enters the attachment plug cap. If a with the provisions of this article. right-angle cap is used, the configuration shall be oriented so (C) Connection to Wiring System. The provisions of this that the grounding member is farthest from the cord, article shall apply to mobile homes intended for connection FPN: Complete details of the 50-ampere plug and recep- to a wiring system rated 120/240 volts, nominal, 3-wire ac, tacle configuration can be found in the National Electrical with a grounded neutral conductor, Manufacturers Association Standard for Dimensions of At- tachment Plugs and Receptacles, ANSI/NEMA WD (D) Listed or Labeled. All electrical materials, devices, 6-1989, Figure 14-50. appliances, fittings, and other equipment shall be listed or labeled by a qualified testing agency and shall be connected Receptacle Cap in an approved manner when installed. UG VG YO oX X' 'Y I1. Mobile and Manufactured Homes 0 w l w 550.10 Power Supply, 1251250-V,50-A,3-pole,4-wire,grounding type (A) Feeder.The power supply to the mobile home shall be Figure 550.10(C) 50-Ampere,1251250-Volt Receptacle and At- a feeder assembly consisting of not more than one listed tachment Plug Cap Configurations, 3-Pole, 44Vire, Grounding-Types, Used for Mobile Home Supply Cords and 50-ampere mobile home power-supply cord with an inte- Mobile Home Parks. 2008 Edition NATIONAL ELECTRICAL CODE 70-467 550.11 ARTICLE 550—MOBILE HOMES,MANUFACTURED HOMES,AND MOBILE HOME PARKS (D) Overall Length of a Power-Supply Cord. The over- be designated as a distribution panelboard, If a fused dis- all length of a power-supply cord, measured from the end tribution panelboard is used,the maximum fuse size for the of the cord, including bared leads, to the face of the attach- mains shall be plainly marked with lettering at least 6 mm ment plug cap shall not be less than 6.4 m (21 ft) and shall (1/a in.) high and visible when fuses are changed. not exceed 11 rn (36'/ ft). The length of the cord from the Where plug fuses and fuseholders are used, they shall face of the attachment plug cap to the point where the cord be tamper-resistant Type S, enclosed in dead-front fuse enters the mobile home shall not be less than 6.0 m (20 ft). panelboards. Electrical distribution panelboards containing (E) Marking. The power-supply cord shall bear the fol- circuit breakers shall also be dead-front type. lowing marking: FPN: See Itp.22 concerning identification of each discon- necting means and each service,feeder,or branch circuit at FOR USE WITH MOBILE HOMES —40 AMPERES the point where it originated and the type marking needed. or (A) Disconnecting Means. A single disconnecting means FOR USE WITH MOBILE HOMES — 50 AMPERES shall be provided in each mobile home consisting of a cir- cuit breaker, or a switch and fuses and its accessories in- (F) Point of Entrance.The point of entrance of the feeder stalled in a readily accessible location near the point of assembly to the mobile home shall be in the exterior wall, entrance of the supply cord or conductors into the mobile floor, or roof. home. The main circuit breakers or fuses shall be plainly marked "Main." This equipment shall contain a solderless (G) Protected. Where the cord passes through walls or type of grounding connector or bar for the purposes of floors, it shall be protected by means of conduits and bush- grounding, with sufficient terminals for all grounding con- stalled or equivalent. The cord shall be permitted to be in- doctors. The terminations of the grounded circuit conduc- stalled within the mobile home walls, provided a continu- tors shall be insulated in accordance with 550.16(A}. The ous raceway having a maximum size of 32 mm (I'/a in.) is disconnecting equipment shall have a rating not less than installed from the branch-circuit panelboard to the under- the calculated load. The distribution equipment, either cir- side of the mobile home floor. cuit breaker or fused type, shall be located a minimum of (H) Protection Against Corrosion and Mechanical 600 mm (24 in.) from the bottom of such equipment to the Damage. Permanent provisions shall be made for the pro- floor level of the mobile home. tection of the attachment plug cap of the power-supply cord FPN: See 550.20(13) for information on disconnecting and any connector cord assembly or receptacle against cor- means for branch circuits designed to energize heating or rosion and mechanical damage if such devices are in an air-conditioning equipment, or both, located outside the exterior location while the mobile home is in transit. mobile home, other than room air conditioners. A distribution panelboard shall be rated not less than 50 (1) Mast Weatherhead or Raceway.Where the calculated amperes and employ a 2-pole circuit breaker rated 40 am- load exceeds 50 amperes or where a permanent feeder is used, Peres fora 40-ampere supply cord, or 50 amperes for a the supply shall be by means of either of the following: 50-ampere supply cord. A distribution panelboard employ- (]} One mast weatherhead installation, installed in accor- ing a disconnect switch and fuses shall be rated 60 amperes dance with Article 230, containing four continuous, in- and shall employ a single 2-pale, 60-ampere fuseholder sulated, color-coded feeder conductors, one of which with 40- or 50-ampere main fuses for 40- or 50-ampere shall be an equipment grounding conductor supply cords, respectively. The outside of the distribution (2) A metal raceway or rigid nonmetallic conduit from the panelboard shall be plainly marked with the fuse size. disconnecting means in the mobile home to the under- The distribution panelboard shall be located in an ac- side of the mobile home, with provisions for the attach- cessible location but shall not be located in a bathroom or a ment to a suitable junction box or fitting to the raceway clothes closet. A clear working space at least 750 min on the underside of the mobile home [with or without (30 in.) wide and 750 mm (30 in.) in front of the distribu- conductors as in 550.10(I)(1)]. The manufacturer shall tion panelboard shall be provided. This space shall extend provide written installation instructions stating the from the floor to the top of the distribution panelboard. proper feeder conductor sizes for the raceway and the size of the junction box to be used. (B) Branch-Circuit Protective Equipment. Branch- circuit distribution equipment shall be installed in each mo- 550.11 Disconnecting Means and Branch-Circuit Pro- bile home and shall include overcurrent protection for each tective Equipment. The branch-circuit equipment shall be branch circuit consisting of either circuit breakers or fuses. permitted to be combined with the disconnecting means as The branch-circuit overcurrent devices shall be rated as a single assembly. Such a combination shall be permitted to follows: 70-468 NATIONAL ELECTRICAL CODE. 2008 Edition ARTICLE 550—MOBILE HOMES,MANUFACTURED HOMES,AND MOBILE HOME PARKS 554.13 (1) Not more than the circuit conductors; and Exception No. 2: Receptacle outlets installed to provide (2) Not more than 150 percent of the rating of a single power for supplemental equipment and lighting on gas- appliance rated 13.3 amperes or more that is supplied fired ranges, ovens, or counter-mounted cooking units shall by an individual branch circuit; but be permitted. (3) Not more than the overcurrent protection size and of Exception No. 5: A single receptacle for refrigeration the type marked on the air conditioner or other motor- equipment shall be permitted to be supplied from an indi- operated appliance. vidual branch circuit rated 15 amperes or greater. (C) Two-Pole Circuit Breakers. Where circuit breakers Countertop receptacle outlets installed in the kitchen are provided for branch-circuit protection, 240-volt circuits shall be supplied by not less than two small-appliance cir- shall be protected by a 2-pole common or companion trip, cuit branch circuits, either or both of which shall be per- or by circuit breakers with identified handle ties. mitted to supply receptacle outlets in the kitchen and other locations specified in 550.I2(B). (D) Electrical Nameplates.A metal nameplate on the out- side adjacent to the feeder assembly entrance shall read as (C) Laundry Area. Where a laundry area is provided, a follows: 20-ampere branch circuit shall be provided to supply the laundry receptacle outlet(s).This circuit shall have no other THIS CONNECTION FOR 1201240-VOLT, outlets. 3-POLE, 4-WIRE, 60-HERTZ, AMPERE SUPPLY (D) General Appliances. (Including furnace, water heater, The correct ampere rating shall be marked in the blank range, and central or room air conditioner,etc.).There shall space. be one or more circuits of adequate rating in accordance p with the following: Exception: For manufactured homes, the manufacturer shall provide in its written installation instructions or in the FPN: For central air conditioning, see Article 440. data plate the minimum ampere rating of the feeder assem- (1) The ampere rating of fixed appliances shall be not over bly or where provided, the service-entrance conductors in- 50 percent of the circuit rating if lighting outlets (re- tended for connection to the manufactured home. The rat- ceptacles, other than kitchen, dining area, and laundry, ing provided shall not be less than the minimum load considered as lighting outlets) are on the same circuit. calculated in accordance with 550.18. (2) For fixed appliances on a circuit without lighting out- lets, the sum of rated amperes shall not exceed the 550.12 Branch Circuits. The number of branch circuits branch-circuit rating. Motor loads or continuous loads required shall be determined in accordance with 550.12(A) shall not exceed 80 percent of the branch-circuit rating. through (E). (3) The rating of a single cord-and-plug-connected appli- (A) Lighting. The number of branch circuits shall be ance on a circuit having no other outlets shall not ex- based on 33 volt-amperes/m2 (3 VA/ft) times outside di- ceed 80 percent of the circuit rating. mensions of the mobile home (coupler excluded) divided (4) The rating of a range branch circuit shall be based on by 120 volts to determine the number of 15- or 20-ampere the range demand as specified for ranges in lighting area circuits, for example, 550.18(B)(5). 3 x length x width (E) Bathrooms. Bathroom receptacle outlets shall be sup- 120 x 15 (or 20) plied by at least one 20-ampere branch circuit. Such circuits shall have no outlets other than as provided for in No.of 15— (or`?0—) ampere circuits 550.13(E)(2). (B) Small Appliances. In kitchens,pantries, dining rooms, 550.13 Receptacle Outlets. and breakfast rooms, two or more 20-ampere small- appliance circuits, in addition to the number of circuits (A) Grounding-Type Receptacle Outlets. All receptacle required elsewhere in this section, shall be provided for all outlets shall comply with the following: receptacle outlets required by 550.13(D) in these rooms. (1) Be of grounding type Such circuits shall have no other outlets. (2) Be installed according to 406.3 Exception No. 1: Receptacle outlets installed solely for the (3) Except where supplying specific appliances, be 15- or electrical supply and support of an electric clock in any the 20-ampere, 125-volt,either single or multiple type,and rooms specified in 550.12(B) shall be permitted. accept parallel-blade attachment plugs 2008 Edition NATIONAL ELECTRICAL CODE 70-469 550.14 ARTICLE 550—MOBILE HOMES.MANUFACTURED HOMES,AND MOBILE HOME PARKS (B) Ground-Fault Circuit Interrupters (GFCI).All 125- (E) Pipe Heating Cable(s) Outlet. For the connection of volt, single-phase. 15- and 20-ampere receptacle outlets in- pipe heating cable(s), a receptacle outlet shall be located on stalled outdoors, in compartments accessible from outside the underside of the unit as follows: the unit, or in bathrooms, including receptacles in lumi- (1) Within 600 mm (2 ft) of the cold water inlet. naires, shall have GFCI protection. GFCI protection shall (2) Connected to an interior branch circuit, other than a be provided for receptacle outlets serving countertops in small-appliance branch circuit. It shall be permitted to kitchens, and receptacle outlets located within 1.8 m (6 ft) use a bathroom receptacle circuit for this purpose. of a wet bar sink. (3) On a circuit where all of the outlets are on the load side Exception: Receptacles h alled Jbr appliances in dedi- of the ground-fault circuit-interrupter. sated spaces, such as for dish+vashers, disposals, refrigera_ (4) This outlet shall not be considered as the receptacle tors,freezers, and laundry equipment. required by 550.13(D)(8). Feeders supplying branch circuits shall be permitted to (F) Receptacle Outlets Not Permitted. Receptacle outlets be protected by a ground-fault circuit-interrupter in lieu of shall not be permitted in the following locations: the provision for such interrupters specified herein. (1) Receptacle outlets shall not be installed within a bath- (C) Cord-Connected Fixed Appliance. A grounding-type tub or shower space. receptacle outlet shall be provided for each cord-connected (2) A receptacle shall not be installed in a face-up position fixed appliance installed. in any countertop. (3) Receptacle outlets shall not be installed above electric (D) Receptacle Outlets Required. Except in the bath, baseboard heaters, unless provided for in the listing or closet, and hall areas, receptacle outlets shall be installed at manufacturer's instructions. wall spaces 600 mm (2 ft) wide or more so that no point along the fluor line is more than 1.8 m (6 ft) measured hori- (G) Receptacle Outlets Not Required. Receptacle outlets zonta]!y from an outlet in that space. In addition, a receptacle shall not be required in the following locations: outlet shall be installed in the following locations: (I) in the wall space occupied by built-in kitchen or ward- robe cabinets (1) Over or adjacent to countertops in the kitchen [at least one on each side of the sink if countertops are on each (2) In the wall space behind doors that can be opened fully side and are 300 mm (12 in.) or over in width]. against a wall surface (2) Adjacent to the refrigerator and freestanding gas-range (3) In room dividers of the lattice type that are less than space. A multiple-type receptacle shall be permitted to 2.5 m (8 ft) long, not solid, and within 150 mm (6 in.) serve as the outlet for a countertop and a refrigerator. of the floor (3) At countertop spaces for built-in vanities. (4) In the wall space afforded by bar-type counters (4) At countertop spaces under wall-mounted cabinets. 550.14 Luminaires and Appliances. (5) In the wall at the nearest point to where a bar-type (A) Fasten Appliances in Transit. Means shall be pro- counter attaches to the wall. vided to securely fasten appliances when the mobile home (6) In the wall at the nearest point to where a fixed room is in transit. (See 550.16 for provisions on grounding.) divider attaches to the wall. (7) In laundry areas within 1.8 m (6 ft) of the intended (B) Accessibility. Every appliance shall be accessible for location of the laundry appliance(s). inspection, service, repair, or replacement without removal (8) At least one receptacle outlet located outdoors and ac- of permanent construction. cessible at grade level and not more than 2.0 in (61/2 ft) (C) Pendants. Listed pendant-type luminaires or pendant above grade. A receptacle outlet located in a compart- cords shall be permitted. ment accessible from the outside of the unit shall be considered an outdoor receptacle. (D) Bathtub and Shower Luminaires. Where a luminaire is installed over a bathtub or in a shower stall, it shall be of (9) At least one receptacle outlet shall be installed in bath- the enclosed and gasketed type listed for wet locations, rooms within 900 mm (36 in.) of the outside edge of each basin.The receptacle outlet shall be located above 550.15 Wiring Methods and Materials. Except as spe- or adjacent to the basin location. This receptacle shall cifically limited in this section, the wiring methods and be in addition to any receptacle that is a part of a materials included in this Code shall be used in mobile luminaire or appliance. The receptacle shall not be en- homes. Aluminum conductors, aluminum alloy conduc- closed within a bathroom cabinet or vanity. tors, and aluminum core conductors such as copper-clad 70470 NATIONAL ELECTRICAL CODF 2008 Edition ARTICLE 550—MOBILE HOMES.MANUFACTURED HOMES,AND MOBILE HOME PARKS 550.16 aluminum shall not be acceptable for use as branch- nominal, or higher) wiring is exposed to moisture or physi- circuit wiring. cal damage, it shall be protected by rigid metal conduit or intermediate metal conduit. The conductors shall be suit- (A) Nonmetallic Boxes. Nonmetallic boxes shall be permit- able for wet locations. ted only with nonmetallic cable or nonmetallic raceways. Exception: Tyne MI cable, electrical metallic tubing, or (B) Nonmetallic Cable Protection. Nonmetallic cable lo- rigid nonmetallic conduit shall be permitted where closely cated 380 mm (15 in.) or less above the floor, if exposed, routed against frames and equipment enclosures. shall be protected from physical damage by covering boards, guard strips, or raceways. Cable likely to be dam- (I) Boxes, Fittings, and Cabinets. Boxes, fittings, and aged by stowage shall be so protected in all cases, cabinets shall be securely fastened in place and shall be supported from a structural member of the home, either (C) Metal-Covered and Nonmetallic Cable Protection. directly or by using a substantial brace. Metal-covered and nonmetallic cables shall be permitted to pass through the centers of the wide side of 2 by 4 studs. Exception: Snap-in-type boxes. Boxes provided with spe- However, they shall be protected where they pass through 2 cial wall or ceiling brackets and wiring devices with inte- by 2 studs or at other studs or frames where the cable or gral enclosures that securely fasten to walls or ceilings and armor would be less than 32 mm 0I/a in.) from the inside are identified for the use shall be permitted without support or outside surface of the studs where the wall covering from a structural member or brace. The testing and ap- materials are in contact with the studs. Steel plates on each proval shall include the wall and ceiling construction sys- side of the cable, or a tube, with not less than 1.35 mm tems for which the boxes and devices are intended to be (0.053 in.) wall thickness shall be required to protect the used. cable. These plates or tubes shall be securely held in place. (J) Appliance Terminal Connections. Appliances having (D) Metal Faceplates. Where metal faceplates are used, branch-circuit terminal connections that operate at tempera- they shall be grounded. tures higher than 60°C (140°F) shall have circuit conduc- tors as described in the following: (E) Installation Requirements. Where a range, clothes (1) Branch-circuit conductors having an insulation suitable dryer, or other appliance is connected by metal-covered for the temperature encountered shall be permitted to cable or flexible metal conduit, a length of not less than be run directly to the appliance. 900 mm (3 ft) of unsupported cable or conduit shall be (2) Conductors having an insulation suitable for the tem- provided to Service the appliance. The cable or flexible perature encountered shall be run from the appliance metal conduit shall be secured to the wall. Type NM or terminal connection to a readily accessible outlet box Type SE cable shall not be used to connect a range or dryer. placed at least 300 mm (1 ft) from the appliance.These This shall not prohibit the use of Type NM or Type SE conductors shall be in a suitable raceway or Type AC cable between the branch-circuit overcurrent protective de- or MC cable of at least 450 mm (18 in.) but not more vice and a junction box or range or dryer receptacle. than 1.8 m (6 ft) in length. (F) Raceways. Where rigid metal conduit or intermediate (K) Component Interconnections. Fittings and connec- metal conduit is terminated at an enclosure with a locknut tors that are intended to be concealed at the time of assem- and bushing connection, two Iocknuts shall be provided, bly shall be listed and identified for the interconnection of one inside and one outside of the enclosure. Rigid nonme- building components. Such fittings and connectors shall be tallic conduit,electrical nonmetallic tubing,or surface race- equal to the wiring method employed in insulation, tem- way shall be permitted. All cut ends of conduit and tubing perature rise, and fault-current withstanding and shall be shall be reamed or otherwise finished to remove rough capable of enduring the vibration and shock occurring in edges. mobile home transportation. (G) Switches. Switches shall be rated as follows: FPN: See 550.19 for interconnection of multiple section (1) For lighting circuits, switches shall be rated not less units. than 10 amperes, 120 to 125 volts, and in no case less than the connected load. 550.16 Grounding. Grounding of both electrical and non- (2) Switches for motor or other loads shall comply with the electrical metal parts in a mobile home shall be through provisions of 404.14. connection to a grounding bus in the mobile home distri- bution panelboard. The grounding bus shall be connected (H) Under-Chassis Wiring (Exposed to Weather). through the green-colored insulated conductor in the supply Where outdoor or under-chassis line-voltage (120 volts, cord or the feeder wiring to the service ground in the 2008 Edition NATIONAL ELECTRICAL CODE 70-471 550.17 ARTICLE 550—MOBILE HOMES,MANUFACTURED HOMES,AND MOBILE HOME PARKS service-entrance equipment located adjacent to the mobile be solid or stranded, insulated or bare, and shall be 8 AWG home location. Neither the frame of the mobile home nor copper minimum, or equivalent. The bonding conductor shall the frame of any appliance shall be connected to the be routed so as not to be exposed to physical damage. grounded circuit conductor in the mobile home. Where the (3) Metallic Piping and Ducts. Metallic gas, water, and distribution panelboard is the service equipment as permit- waste pipes and metallic air-circulating ducts shall be con- ted by 550.32(B), the neutral conductors and the equipment sidered bonded if they are connected to the terminal on the grounding bus shall be connected. chassis [see 550.16(C)(1)] by clamps, solderless connec- (A) Grounded Conductor. tors, or by suitable grounding-type straps. (1) insulated. The grounded circuit conductor shall be in- (4) Metallic Roof and Exterior Coverings. Any metallic sulated from the grounding conductors and frorn equipment roof and exterior covering shall be considered bonded if the enclosures and other grounded parts. The grounded circuit following conditions are met: conductor terminals in the distribution panelboard and in (1) The metal panels overlap one another and are securely ranges, clothes dryers, counter-mounted cooking units, and attached to the wood or metal frame parts by metallic wall-mounted ovens shall be insulated from the equipment fasteners. enclosure. Bonding screws, straps, or buses in the distribu- (2) The lower panel of the metallic exterior covering is tion panelboard or in appliances shall be removed and dis- secured by metallic fasteners at a cross member of the carded. Where the distribution panelboard is the service chassis by two metal straps per mobile home unit or equipment as permitted by 550.32(B), the neutral conduc- section at opposite ends. tors and the equipment grounding bus shall be connected. The bonding strap material shall be a minimum of (2) Connections of Ranges and Clothes Dryers.Connec- 100 mm (4 in.) in width of material equivalent to the skin tions of ranges and clothes dryers with 1201240-volt,3-wire or a material of equal or better electrical conductivity. The ratings shall be made with 4-conductor cord and 3-pole, straps shall be fastened with paint-penetrating fittings such 4-wire, grounding-type plugs or by Type AC cable, Type as screws and starwashers or equivalent. MC cable,or conductors enclosed in flexible metal conduit. 550.17 Testing. (B) Equipment Grounding Means. (A) Dielectric Strength Test. The wiring of each mobile (1) Supply Cord or Permanent Feeder. The green- home shall be subjected to a 1-minute, 900-volt, dielectric colored insulated grounding wire in the supply cord or per- strength test (with all switches closed) between live parts manent feeder wiring shall be connected to the grounding (including neutral conductor) and the mobile home ground. bus in the distribution panelboard or disconnecting means. Alternatively, the test shall be permitted to be performed at 1080 volts for I second. This test shall be performed after (2) Electrical System. In the electrical system, all exposed branch circuits are complete and after luminaires or appli- metal parts, enclosures, frames, luminaire canopies, and so ances are installed. forth shall be effectively bonded to the grounding terminal or enclosure of the distribution panelboard. Exception: Listed luminaires or appliances shall not be re- quired to withstand the dielectric strength rest. (3) Cord-Connected Appliances. Cord-connected appli- (B) Continuity and Operational Tests and Polarity ances, such as washing machines, clothes dryers, and re- frigerators, and the electrical system of gas ranges and so Checks. Each mobile home shall be subjected to all of the forth,shall be grounded by means of a cord with an equipment fallowing: grounding conductor and grounding-type attachment plug. (1) An electrical continuity test to ensure that all exposed electrically conductive parts are properly bonded (C) Bonding of Non–Current-Carrying Metal Parts. (2) An electrical operational test to demonstrate that all (1) Exposed Non–Current-Carrying Metal Parts. All equipment, except water heaters and electric furnaces, exposed non--current-carrying metal parts that may become is connected and in working order energized shall be effectively bonded to the grounding ter- (3) Electrical polarity checks of permanently wired equip- minal or enclosure of the distribution panelboard. A bond- ment and receptacle outlets to determine that connec- ing conductor shall be connected between the distribution tions have been properly made panelboard and accessible terminal on the chassis. 550.18 Calculations. The following method shall be em- (2) Grounding Terminals. Grounding terminals shall be of ployed in calculating the supply-cord and distribution- the solderless type and listed as pressure-terminal connectors panelboard load for each feeder assembly for each mobile recognized for the wire size used.The bonding conductor shall home in lieu of the procedure shown in Article 220 and 70-472 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 550—MOBILE HOMES,MANUFACTURED HOMES,AND MOBILE HOME PARKS 550,20 shall be based on a 3-wire, 1201240-volt supply with 120- (6) If outlets or circuits are provided for other than factory- volt loads balanced between the two ungrounded eondua- installed appliances, include the anticipated load. tors of the 3-wire system. FPN: Refer to Annex D. Example DH, for an illustration (A) Lighting, Small-Appliance, and Laundry Load. of the application of this calculation. (1) Lighting Volt-Amperes.Length times width of mobile (C) Optional Method of Calculation for Lighting and Ap- home floor (outside dimensions) times 33 volt-ampereslm2 pliance Load. The optional method for calculating lighting (3 VAM2), for example, length x width x 3 = lighting and appliance load shown in 220.82 shall be permitted. volt-amperes. 550,19 interconnection of Multiple-Section Mobile or (2) Small-Appliance Volt-Amperes. Number of circuits Manufactured Home Units. times 1500 volt-amperes for each 20-ampere appliance re- ceptacle circuit (see definition of Appliance, Portable, with (A) Wiring Methods. Approved and listed fixed-type wir- a fine print note in 550.2), for example, number of circuits ing methods shall be used to join portions of a circuit that x 1500 = small-appliance volt-amperes. must be electrically joined and are located in adjacent sec- tions after the home is installed on its support foundation. (3) Laundry Area Circuit Volt-Amperes. 1500 volt- The circuit's junction shall be accessible for disassembly amperes. when the home is prepared for relocation. (4) Total Volt-Amperes. Lighting volt-amperes plus FPN: See 550.15(x) for component interconnections, small-appliance volt-amperes plus laundry area volt- amperes equals total volt-amperes. (B) Disconnecting Means. Expandable or multiunit manu- factured homes, not having permanently installed feeders, (5) Net Volt-Amperes. First 3000 total volt-amperes at that are to be moved from one location to another shall be 100 percent plus remainder at 35 percent equals volt-amperes permitted to have disconnecting means with branch-circuit to be divided by 240 volts to obtain current(amperes)per leg. protective equipment in each unit when so located that after assembly or joining together of units, the requirements of (B) Total Load for Determining Power Supply.Total load 550.10 will be met. for determining power supply is the sum of the following: (1) Lighting and small-appliance load as calculated in 550.20 Outdoor Outlets, Luminaires, Air-Cooling 550.1 8(A)(5). Equipment, and So Forth. (2) Nameplate amperes for motors and heater loads (ex- (A) Listed for Outdoor Use. Outdoor luminaires and haust fans, air conditioners, electric, gas, or oil heat- equipment shall be listed for wet locations or outdoor use. ing). Omit smaller of the heating and cooling loads, Outdoor receptacles shall comply vxith 406.8. Where located except include blower motor if used as air-conditioner on the underside of the home or located under roof extensions evaporator motor. Where an air conditioner is not in- or similarly protected locations,outdoor luminaires and equip- stalled and a 40-ampere power-supply cord is provided, rent shall be listed for use in damp locations. allow 15 amperes per leg for air conditioning. (3) Twenty-five percent of current of largest motor in (2). (B) Outside Heating Equipment,Air-Conditioning Equip- (4) Total of nameplate amperes for waste disposer, dish- ment,or Both.A mobile home provided with a branch circuit washer,water heater,clothes dryer,wall-mounted oven, designed to energize outside heating equipment, air- cooking units. Where the number of these appliances conditioning equipment, or both, located outside the mobile exceeds three, use 75 percent of total. home, other than room air conditioners, shall have such (5) Derive amperes for freestanding range (as distin- branch-circuit conductors terminate in a listed outlet box, or guished from separate ovens and cooking units) by di- disconnecting means, located on the outside of the mobile viding the following values by 240 volts: home. A label shall be permanently affixed adjacent to the outlet box and shall contain the following information: Nameplate Rating Use THIS CONNECTION IS FOR HEATING (watts) (volt-amperes) AND/OR AIR-CONDITIONING EQUIPMENT. 0- 10,000 80 percent of rating THE BRANCH CIRCUIT 1S RATED AT NOT Over 10,000- 12,500 8,000 MORE THAN AMPERES, Over 12,500- 13,500 8.400 AT VOLTS, 60 HERTZ, Over 13,500- 14,500 8,800 CONDUCTOR AMPACITY. Over 14,500- 15,500 9,200 Over 15,500- 16,500 9,600 A DISCONNECTING MEANS SHALL BE LOCATED Over 16,500- 17,500 10,000 WITHIN SIGHT OF THE EQUIPMENT. 2008 Edition NATIONAL ELECTRICAL CODE 70-473 550.25 ARTICLE 550 MOBILE HOMES,MANUFACTURED HOMES.AND MOBILE HOME PARKS The correct voltage and ampere rating shall be given. Table 550.31 Demand Factors for Services and Feeders The tag shall be not less than 0.51 mm (0.020 in.) thick etched brass, stainless steel, anodized or alclad aluminum, Number of Demand or equivalent. The tag shall not be less than 75 mm by Mobile Homes Factor(%) 45 mm (3 in, by la/a in.) minimum size. 1 100 2 55 550.25 Arc-Fault Circuit-Interrupter Protection. 3 44 4 39 (A) Definition. Arc-fault circuit interrupters are defined in 5 -i3 Article 210.12(A). 6 29 7-9 28 10-12 27 (B) Bedrooms of Mobile Homes and Manufactured 13-15 26 Homes. All 120-volt branch circuits that supply 15- and 16-21 25 20-ampere outlets installed in bedrooms of mobile homes 22-40 24 and manufactured homes shall comply with 210.12(B). 41-60 23 61 and over 22 III. Services and Feeders be installed in or on a manufactured home, provided that all 550.30 Distribution System. The mobile home park sec- of the following conditions are met: ondary electrical distribution system to mobile home lots (1) The manufacturer shall include in its written installa- shall be single-phase, 120/240 volts, nominal. For the pur- tion instructions information indicating that the home pose of Part III, where the park service exceeds 240 volts, shall be secured in place by an anchoring system or nominal, transformers and secondary distribution panel- installed on and secured to a permanent foundation. boards shall be treated as services. (2) The installation of the service shall comply with Part I through Part VII of Article 230. 550.31 Allowable Demand Factors. Park electrical wiring (3) Means shall be provided for the connection of a systems shall be calculated (at 120/240 volts) on the larger grounding electrode conductor to the service equipment of the following: and routing it outside the structure. (1) 16,000 volt-amperes for each mobile home lot (4) Bonding and grounding of the service shall be in ac- (2) The load calculated in accordance with 550.18 for the cordance with Part I through fart V of Article 250. largest typical mobile home that each lot will accept (5) The manufacturer shall include in its written installa- tion instructions one method of grounding the service It shall be permissible to calculate the feeder or ser- equipment at the installation site.The instructions shall vice load in accordance with Table 550.31. No demand clearly state that other methods of grounding are found factor shall be allowed for any other load, except as in Article 250. provided in this Code. (6) The minimum size grounding electrode conductor shall 550.32 Service Equipment. be specified in the instructions. (7) A red warning label shall be mounted on or adjacent to (A) Mobile Home Service Equipment. The mobile home the service equipment.The label shall state the following: service equipment shall be located adjacent to the mobile home and not mounted in or on the mobile home. The WARNING service equipment shall be located in sight from and not DO NOT PROVIDE ELECTRICAL POWER more than 9.0 m (30 ft) from the exterior wall of the mobile UNTIL THE GROUNDING ELECTRODE(S) home it serves.The service equipment shall be permitted to IS INSTALLED AND CONNECTED be located elsewhere on the premises, provided that a dis- (SEE INSTALLATION INSTRUCTIONS). connecting means suitable for use as service equipment is Where the service equipment is not installed in or on located within sight from and not more than 9.0 m (30 ft) the unit, the installation shall comply with the other provi- from the exterior wall of the mobile home it serves and is sions of this section. rated not less than that required for service equipment per 550.32(C). Grounding at the disconnecting means shall be (C) Rating.Mobile home service equipment shall be rated in accordance with 250.32. at not less than 100 amperes at 120/240 volts, and provi- sions shall be made for connecting a mobile home feeder (B) Manufactured Home Service Equipment. The assembly by a permanent wiring method. Power outlets manufactured home service equipment shall be permitted to used as mobile home service equipment shall also be 70-474 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 551 —RECREATIONAL VEHICLES AND RECREATIONAL VEHICLE PARKS 551.2 permitted to contain receptacles rated up to 50 amperes Exception: For an existing feeder that is installed between with appropriate overcurrent protection. Fifty-ampere re- the service equipment and a disconnecting means as cov- ceptacles shall conform to the configuration shown in ered in 550.32(A), it shall be permitted to omit the equip- Figure 550.10(C). ment grounding conductor where the grounded circuit con- FPN: Complete details of the 50-ampere plug and recep- ductor is grounded at the disconnecting means in tacle configuration can be found in ANSUNEMA WD accordance with 250.32(B) Exception. 6-1989, National Electrical Manufacturers Association, Standard for Wiring Devices—Dimensional Requirements, (B) Feeder Capacity. Mobile home and manufactured Figure 14-50. home lot feeder circuit conductors shall have a capacity not less than the loads supplied, shall be rated at not less than (D) Additional Outside Electrical Equipment.Means for 100 amperes, and shall be permitted to be sized in accor- connecting a mobile home accessory building or structure dance with 310.15(B)(6). or additional electrical equipment located outside a mobile home by a fixed wiring method shall be provided in either the mobile home service equipment or the local external disconnecting means permitted in 550.32(A). ARTICLE 551 (E) Additional Receptacles. Additional receptacles shall Recreational Vehicles and Recreational be permitted for connection of electrical equipment located Vehicle Parks outside the mobile home, and all such 125-volt, single- phase, 15- and 20-ampere receptacles shall be protected by a listed ground-fault circuit interrupter. 1. General (F) Mounting Height. Outdoor mobile home disconnect- 551.1 Scope. The provisions of this article cover the elec- ing means shall be installed so the bottom of the enclosure trical conductors and equipment other than low-voltage and containing the disconnecting means is not less than automotive vehicle circuits or extensions thereof, installed 600 mm (2 ft) above finished grade or working platform. within or on recreational vehicles, the conductors that con- The disconnecting means shall be installed so that the cen- nect recreational vehicles to a supply of electricity, and the ter of the grip of the operating handle, when in the highest installation of equipment and devices related to electrical position, is not more than 2.0 m (6 ft 7 in.) above the installations within a recreational vehicle park. finished grade or working platform. FPN: For information on low-voltage systems, refer to NFPA 1192-2005, Standard on Recreational Vehicles, and (G) Marking. Where a 1251250-volt receptacle is used in ANSI/RV1A 12V-2005, Standard for L )w Voltage Systems mobile home service equipment, the service equipment in Conversion and Recreational Vehicles. shall be marked as follows: TURN DISCONNECTING SWITCH OR 551.2 Definitions. (See Article 100 for additional defini- CIRCUIT BREAKER OFF BEFORE INSERTING lions.) OR REMOVING PLUG. PLUG MUST BE Air-Conditioning or Comfort-Cooling Equipment.All of FULLY INSERTED OR REMOVED. that equipment intended or installed for the purpose of pro- cessing the treatment of air so as to control simultaneously The marking shall be located on the service equipment its temperature, humidity, cleanliness, and distribution to adjacent to the receptacle outlet. meet the requirements of the conditioned space. 550.33 Feeder, Appliance, Fixed. An appliance that is fastened or other- (A) Feeder Conductors. Feeder conductors shall comply Vise secured at a specific location. with the following: Appliance, Portable. An appliance that is actually (1) Feeder conductors shall consist of either a listed cord, moved or can easily be moved from one place to another factory installed in accordance with 550.10(B), or a in normal use. permanently installed feeder consisting of four insu- FPN: For the purpose of this article, the following major lated,color-coded conductors that shall be identified by appliances, other than built-in, are considered portable if the factory or field marking of the conductors in com- cord connected: refrigerators, range equipment, clothes pliance with 310.12. Equipment grounding conductors washers, dishwashers without booster heaters, or other shall not be identified by stripping the insulation. similar appliances. (2) Feeder conductors Shall be installed in compliance with Appliance, Stationary. An appliance that is not easily 250.32(B). moved from one place to another in normal use. 2008 Edition NATIONAL ELECTRICAL CODE 70-475 551.4 ARTICLE 551 RECREATIONAL VEHICLES AND RECREATIONAL VEHICLE PARKS Camping Trailer. A vehicular portable unit mounted on or maintained for occupancy by recreational vehicles of the wheels and constructed with collapsible partial side wally general public as temporary living quarters for recreation or that fold for towing by another vehicle and unfold at the vacation purposes. campsite to provide temporary living quarters for recre- ational, camping, or travel use. (See Recreational Vehicle.) Recreational Vehicle Site. A plot of ground within a rec- reational vehicle park set aside for the accommodation of a Converter. A device that changes electrical energy from recreational vehicle on a temporary basis. It can be used as one form to another, as from alternating current to direct either a recreational vehicle site or as a camping unit site. current. Recreational Vehicle Site Feeder Circuit Conductors. Dead Front (as applied to switches, circuit breakers, The conductors from the park service equipment to the switchboards, and distribution panelboards). Designed, recreational vehicle site supply equipment, constructed, and installed so that no current-carrying parts are normally exposed on the front. Recreational Vehicle Site Supply Equipment.The neces- sary equipment, usually a power outlet, consisting of a cir- Disconnecting Means. The necessary equipment usually suit breaker or switch and fuse and their accessories, lo- consisting of a circuit breaker or switch and fuses,and their cated near the paint of entrance of supply conductors to a accessories, located near the paint of entrance of supply conductors in a recreational vehicle and intended to consti- recreational vehicle site and intended to constitute the dis- tute the means of cutoff for the supply to that recreational connecting means for the supply to that site. vehicle. Recreational Vehicle Stand. That area of a recreational Distribution Panelboard.A single panel or group of panel vehicle site intended for the placement of a recreational units designed for assembly in the form of a single panel, vehicle. including buses, and with or without switches and/or auto- Transformer. A device that, when used, raises or lowers static overcurrent protective devices for the control of light, the voltage of alternating current of the original source. heat, or power circuits of small individual as well as aggre- gate capacity, designed to be placed in a cabinet or cutout Travel Trailer. A vehicular unit, mounted on wheels, de- box placed in or against a wall or partition and accessible signed to provide temporary living quarters for recreational, only from the front, camping, or travel use, of such size or weight as not to require special highway movement permits when towed by Frame. Chassis rail and any welded addition thereto of a motorized vehicle, and of gross trailer area less than metal thickness of 1.35 mm (0.053 in.) or greater. 30 m' (320 ft`). (See Recreational Vehicle.) Low Voltage. An electromotive force rated 24 volts, Truck Camper. A portable unit constructed to provide nominal, or less, supplied from a transformer, converter, temporary living quarters for recreational, travel, or camp- or battery. ing use,consisting of a roof, floor, and sides, designed to be Motor Home.A vehicular unit designed to provide tempo- loaded onto and unloaded from the bed of a pickup truck. racy living quarters for recreational, camping, or travel use (See Recreational Vehicle.) built on or permanently attached to a self-propelled motor vehicle chassis or on a chassis cab or van that is an integral 551.4 General Requirements. part of the completed vehicle. (See Recreational Vehicle.) (A) Not Covered. A recreational vehicle not used for the Power-Supply Assembly. The conductors, including un- purposes as defined in 551.2 shall not be required to meet grounded, grounded, and equipment grounding conductors, the provisions of Part I pertaining to the number or capacity the connectors, attachment plug caps, and all other fittings, of circuits required. It shall, however, meet all other appli- grommets,or devices installed for the purpose of delivering cable requirements of this article if the recreational vehicle energy from the source of electrical supply to the distribu- is provided with an electrical installation intended to be tion panel within the recreational vehicle. energized from a 120-volt,208Y/120-volt, or 120/240-volt, Recreational Vehicle. A vehicular-type unit primarily de- nominal, ac power-supply system. signed as temporary living quarters for recreational, camp- (B) Systems. This article covers combination electrical ing, or travel use,which either has its own motive power or systems, generator installations, and 120-volt, 208Y/120- is mounted on or drawn by another vehicle. The basic en- volt, or 1201240-volt, nominal, systems. tities are travel trailer, camping trailer, truck camper, and motor home. FPN: For information on low-voltage systems, refer to NFPA 1192-2005. Standard on Recreational Vehicles, and Recreational Vehicle Park.A plot of land upon which two ANSURVIA 12V-2005, Standard for Low Voltage Stistem.s or more recreational vehicle sites are located, established, in Conversion and Recreational Vehicles. 70-476 NATIONAL ELECTRICAL CODE 2005 Edition ARTICLE 551—RECREATIONAL VEHICLES AND RECREATIONAL VEHICLE PARKS 551.30 II. Combination Electrical Systems voltage system has an external connection for low-voltage power, the connector shall have a configuration that will 551.20 Combination Electrical Systems. not accept ac power. (A) General. Vehicle wiring suitable for connection to a battery or do supply source shall be permitted to be con- 1II. Other Power Sources nected to a 120-volt source, provided the entire wiring sys- tem and equipment are rated and installed in full confor- 551.30 Generator Installations. mity with Parts I, II, 111, IV, and V requirements of this article covering 120-volt electrical systems. Circuits fed (A) Mounting. Generators shall be mounted in such a manner as to be effectively bonded to the recreational ve- from ac transformers shall not supply do appliances. hicle chassis. (B) Voltage Converters (120-Volt Alternating Current to Low-Voltage Direct Current). The 120-volt ac side of (B) Generator Protection. Equipment shall be installed to the voltage converter shall be wired in full conformity with ensure that the current-carrying conductors from the engine Parts I, 1I, III, 1V, and V requirements of this article for generator and from an outside source are not connected to a vehicle circuit at the same time. 120-volt electrical systems. Receptacles used as disconnecting means shall be ac- Exception: Converters supplied as an integral part of a cessible (as applied to wiring methods) and capable of in- listed appliance shall not be subject to 551.20(B). terrupting their rated current without hazard to the operator. All converters and transformers shall be listed for use in (C) Installation of Storage Batteries and Generators. recreational vehicles and designed or equipped to provide Storage batteries and internal-combustion-driven generator overtemperature protection.To determine the converter rat- units (subject to the provisions of this Code) shall be Be- ing, the following formula shall be applied to the total cured in place to avoid displacement from vibration and connected load, including average battery charging rate, of road shock. all 12-volt equipment: The first 20 amperes of load at 100 percent, plus (D) Ventilation of Generator Compartments. Compart- The second 20 amperes of load at 50 percent, plus ments accommodating internal-combustion-driven genera- All load above 40 amperes at 25 percent for units shall be provided with ventilation in accordance Exception: A low-voltage appliance that is controlled by a with instructions provided by the manufacturer of the gen- Momentary switch (normally open) that has no means for erator unit. holding in the closed position or refrigerators with a 120- FPN: For generator compartment construction require- volt Junction shall not be considered as a connected load ments, see NFPA 1192-2005, Standard on Recreational when determining the required converter rating. Momen- Vehicles. tarily energized appliances shall be limited to those used to prepare the vehicle for occupancy or travel. (E) Supply Conductors. The supply conductors from the engine generator to the first termination on the vehicle shall (C) Bonding Voltage Converter Enclosures. The non— he of the stranded type and be installed in listed flexible current-carrying metal enclosure of the voltage converter conduit or listed liquidtight flexible conduit. The point of shall be connected to the frame of the vehicle with a mini- first termination shalt be in one of the following: mum 8 AWG copper conductor.The voltage converter shall (1) Panelboard be provided with a separate chassis bonding conductor that (2) ]unction box with a blank cover shall not be used as a current-carrying conductor. (3) Junction box with a receptacle (D) Dual-Voltage Fixtures,Including Luminaires orAp- (4) Enclosed transfer switch pliances. Fixtures, including luminaires, or appliances hav- (5) Receptacle assembly listed in conjunction with the ing both 120-volt and low-voltage connections shall be generator listed for dual voltage. The panelboard or junction box with a receptacle shall (E) Autotransformers. Autotransformers shall not be used. be installed within the vehicle's interior and within 450 mm (18 in.) of the compartment wall but not inside the com- (F) Receptacles and Plug Caps. Where a recreational ve- partment. If the generator is below the floor level and not in hicle is equipped with an ac system, a low-voltage system, a compartment, the panelboard or junction box with recep- or both, receptacles and plug caps of the low-voltage sys- tacle shall be installed within the vehicle interior within tem shall differ in configuration from those of the ac sys- 450 mm (18 in.) of the point of entry into the vehicle. A tem. Where a vehicle equipped with a battery or other low- junction box with a blank cover shall be mounted on the 2008 Edition NATIONAL ELECTRICAL CODE 70477 551.31 ARTICLE 551—RECREATIONAL VEHICLES AND RECREATIONAL VEHICLE PARKS compartment wall and shall be permitted inside or outside IV. Nominal 120-Volt or 1201240-Volt Systems the compartment. A receptacle assembly listed in conjunc- tion with the generator shall be mounted in accordance with 551.40 120-Volt or 120/240-Volt, Nominal, Systems. its listing. If the generator is below floor level and not in a (A) General Requirements. The electrical equipment and compartment, the junction box with blank cover shall be material of recreational vehicles indicated for connection to mounted either to any part of the generator supporting a wiring system rated 120 volts, nominal, 2-wire with structure (but not to the generator) or to the vehicle floor equipment grounding conductor, or a wiring system rated within 450 mm (18 in.) of any point directly above the 1201240 volts, nominal, 3-wire with equipment grounding generator on either the inside or outside of the floor surface, conductor, shall be listed and installed in accordance with Overcurrent protection in accordance with 240.4 shall be the requirements of Parts I, I1, III, 1V, and V of this article. provided for supply conductors as an integral part of a Electrical equipment connected line-to-line shall have a listed generator or shall be located within 450 min (18 in.) voltage rating of 208-230 volts. of their point of entry into the vehicle. (B) Materials and Equipment. Electrical materials, de- 551.31 Multiple Supply Source. vices, appliances, fittings, and other equipment installed in, intended for use in, or attached to the recreational vehicle (A) Multiple Supply Sources. Where a multiple supply shall be listed. All products shall be used only in the man- system consisting of an alternate power source and a ner in which they have been tested and found suitable for power-supply cord is installed,the feeder from the alternate the intended use. power source shall be protected by an overcurrent protec- tive device. Installation shall be in accordance with (C) Ground-Fault Circuit-Interrupter Protection. The 551.30(A), 551.30(B), and 551.40. internal wiring of a recreational vehicle having only one 15- or 20-ampere branch circuit as permitted in 551.42(A) (B) Multiple Supply Sources Capacity.The multiple sup- and (B) shall have ground-fault circui[-interrupter protec- ply sources shall not be required to be of the same capacity. tion for personnel.The ground-fault circuit interrupter shall be installed at the point where the power supply assembly (C) Alternate Power Sources Exceeding 30 Amperes. If terminates within the recreational vehicle. Where a sepa- an alternate power source exceeds 30 amperes, 120 volts, rable cord set is not employed, the ground-fault circuit in- nominal, it shall be permissible to wire it as a 120-volt, terrupter shall be permitted to be an integral part of the nominal, system, a 208Y1120-volt, nominal, system, or a attachment plug of the power supply assembly.The ground- ]201240-volt, nominal, system, provided an overcurrent fault circuit interrupter shall provide protection also under protective device of the proper rating is installed in the the conditions of an open grounded circuit conductor, inter- feeder. changed circuit conductors, or both. (D) Power-Supply Assembly Not Less Than 30 Am- 551.41 Receptacle Outlets Required. peres. The external power-supply assembly shall be per- mitted to be less than the calculated load but not less than (A) Spacing. Receptacle outlets shall be installed at wall spaces 600 mm (2 ft) wide or more so that no point along 30 amperes and shall have overcurrent protection not the floor line is more than 1.8 m (6 ft), measured horizon- tally, from an outlet in that space. sembly. Exception No. 1: Bath and hall areas. 551.32 Other Sources. Other sources of ac power, such as Exception No. 2: Wall spaces occupied by kitchen cabinets, inverters, motor generators, or engine generators, shall be wardrobe cabinets, built-in furniture, behind doors that listed for use in recreational vehicles and shall be installed may open fully against a wall surface, or similar facilities. in accordance with the terms of the listing. Other sources of ac power shall be wired in full conformity with the require- (B) Location. Receptacle outlets shall be installed as ments in Parts I, II, III, IV, and V of this article covering follows: 120-volt electrical systems. (1) Adjacent to countertops in the kitchen [at least one on each side of the sink if countertops are on each side and 551.33 Alternate Source Restriction. Transfer equip- are 300 mm (12 in.) or over in width] ment, if not integral with the listed power source, shall be (2) Adjacent to the refrigerator and gas range space, except installed to ensure that the current-carrying conductors where a gas-fired refrigerator or cooking appliance, from other sources of ac power and from an outside source requiring no external electrical connection, is factory are not connected to the vehicle circuit at the same time. installed 70-478 NATIONAL ELECTRICAL CODE 2008 Edilion ARTICLE 551—RECREATIONAL VEHICLES AND RECREATIONAL VEHICLE PARKS 551.44 (3) Adjacent to countertop spaces of 300 mm (12 in.) or outlets, and fixed appliances shall be permitted. Such rec- more in width that cannot be reached from a receptacle reational vehicles shall be permitted to be equipped with required in 551.41(B)(1) by a cord of 1.8 m (6 ft) distribution panelboards rated 120 volts maximum or without crossing a traffic area, cooking appliance, or 1201240 volts maxim Um. and listed.for 30-ampere appIica- sink tion supplied by the appropriate power-supply assemblies. Not more than two 120-volt thermostatically controlled ap- pliances (e.g., air conditioner and water heater) shall be provided, each 125-volt, single-phase, 15- or 20-ampere installed in such systems unless appliance isolation switch- receptacle outlet shall have ground-fault circuit-interrupter ing, energy management systems, or similar methods are protection for personnel in the following locations: used. (1) Adjacent to a bathroom lavatory (2) Where the receptacles are installed t0 serve the coun- Exception: Additional IS- or 20-ampere circuits shall be tertop surfaces and are within 1.8 m (6 ft) of any lava- Permitted where a listed energy management system rated at 30-ampere maximum is employed within the system. tory or sink Exception No. 1: Receptacles installed for appliances FPN: See 210.23(A) for permissible loads. See 551.45(C) for main disconnect and overcurrent protection in dedicated spaces, such as for dishwashers, dispos- requirements. als, refrigerators,freezers, and laundry equipment. Exception No. 2: Single receptacles for interior con- (D) More Than Five Circuits Without a Listed Energy nections of expandable room sections. Management System. A 50-ampere, 1201208-240-volt Exception No. 3: De-energized receptacles that are power-supply assembly and a minimum 50-ampere-rated distribution panelboard shall be used where six or more within 1.8 m (6 ft] of any sink or lavatory due to the circuits are employed. The load distribution shall ensure a retraction of the expandable room section. reasonable current balance between phases. (3) In the area occupied by a toilet, shower, tub, or any combination thereof 551.43 Branch-Circuit Protection. (4) On the exterior of the vehicle (A) Rating. The branch-circuit overcurrent devices shall Exception: Receptacles that are located inside of an be rated as follows: access panel that is installed on the exterior of the vehicle to supply power for an installed appliance shall (1) Not more than the circuit conductors, and not be required to have ground fault circuit-interrupter (2) Not more than 150 percent of the rating of a single protection. an rated 13.3 amperes or more and supplied by an individual branch circuit, but The receptacle outlet shall be permitted in a listed lu- (3) Not more than the overcurrent protection size marked minaire.A receptacle outlet shall not be installed in a tub or on an air conditioner or other motor-operated combination tub—shower compartment. appliances (D) Face-Up Position. A receptacle shall not be installed (B) Protection for Smaller Conductors. A 20-ampere in a face-up position in any countertop or similar horizontal fuse or circuit breaker shall be permitted for protection for surfaces within the living area. fixtures, including luminaires, leads, cords, or small appli- 551.42 Branch Circuits Required. Each recreational ve- ances, and 14 AWG tap conductors, not over 1.8 m (6 ft) hicle containing an ac electrical system shall contain one of long for recessed luminaires. the circuit arrangements in 551.42(A) through (D). (C) Fifteen-Ampere Receptacle Considered Protected (A) One 15-Ampere Circuit. One 15-ampere circuit to by 20 Amperes.if more than one receptacle or load is on a supply lights, receptacle outlets, and fixed appliances. Such branch circuit, a 15-ampere receptacle shall be permitted to recreational vehicles shall be equipped with one 15-ampere be protected by a 20-ampere fuse or circuit breaker. switch and fuse or one 15-ampere circuit breaker. 551.44 Power-Supply Assembly. Each recreational ve- (B) One 20-Ampere Circuit. One 20-ampere circuit to hicle shall have only one of the main power-supply assem- supply lights, receptacle outlets, and fixed appliances. Such blies covered in 551.44(A) through (D). recreational vehicles shall be equipped with one 20-ampere switch and fuse or one 20-ampere circuit breaker. (A) Fifteen-Ampere Main Power-Supply Assembly. Recreational vehicles wired in accordance with 551.42(A) (C) Two to Five 15- or 20-Ampere Circuits.A maximum shall use a listed 15-ampere or larger main power-supply of five 15-or 20-ampere circuits to supply lights,receptacle assembly. 2008 Edition NATIONAL ELECTRICAL CODE 70-479 551.45 ARTICLE 551 —RECREATIONAL VEHICLES AND RECREATIONAL VEHICLE PARKS (B) Twenty-Ampere Main Power-Supply Assembly. (1) Separable. Where a separable power-supply assembly Recreational vehicles wired in accordance with 551.42(B) consisting of a cord with a female connector and molded shall use a listed 20-ampere or larger main power-supply attachment plug cap is provided, the vehicle shall be assembly. equipped with a permanently mounted, flanged surface inlet (male, recessed-type motor-base attachment plug) wired di- (C) Thirty-Ampere Main Power-Supply Assembly. Rec- rectly to the distribution panelboard by an approved wiring reational vehicles wired in accordance with 55 t.42(C) method. The attachment plug cap shall be of a listed type. shall use a listed 30-ampere or larger main power-supply assembly. (2) Permanently Connected. Each power-supply assem- bly shall be connected directly to the terminals of the dis- (D) Fifty-Ampere Power-Supply Assembly. Recreational tribution panelboard or conductors within a junction box vehicles wired in accordance with 551.42(D) shall use a and provided with means to prevent strain from being listed 50-ampere, 1201208--240-volt main power-supply transmitted to the terminals. The ampacity of the conduc- assembly. tors between each junction box and the terminals of each distribution panelboard shall be at least equal to the ampac- 551.45 Distribution Panelboard. ity of the power-supply cord.The supply end of the assem- bly shall be equipped with an attachment plug of the type (A) Listed and Appropriately Rated. A listed and appro- described in 551.46(C). Where the cord passes through the priately rated distribution panelboard or other equipment walls or floors, it shall be protected by means of conduit specifically listed for this purpose shall be used. The and bushings or equivalent. The cord assembly shall have grounded conductor termination bar shall be insulated from permanent provisions for protection against corrosion and the enclosure as provided in 551.54(C), An equipment mechanical damage while the vehicle is in transit. grounding terminal bar shall be attached inside the enclo- sure of the panelboard. (B) Cord. The cord exposed usable length shall be mea- sured from the point of entrance to the recreational vehicle (B) Location. The distribution panelboard shall be in- or the face of the flanged surface inlet(motor-base attachment stalled in a readily accessible location with the RV in the plug) to the face of the attachment plug at the supply end. setup mode. Working clearance for the panelboard with the The cord exposed usable length, measured to the point RV in the setup mode shall be not less than 600 mm(24 in.) of entry on the vehicle exterior, shall be a minimum of wide and 750 mm (30 in.) deep. 7.5 m (25 ft) where the point of entrance is at the side of the vehicle or shall be a minimum 9.0 m (30 ft) where the Exception No. 1: Where the panelboard cover is exposed point of entrance is at the rear of the vehicle. to tine inside aisle space, one of the working clearance Where the cord entrance into the vehicle is more than dimensions shalt be permitted to be reduced to a minimum 900 mm (3 ft)above the ground,the minimum cord lengths of 550 nun (22 in.). A panelboard is considered exposed above shall be increased by the vertical distance of the cord where the panelboard cover is within 50 norm (2 in.) of the entrance heights above 900 mm (3 ft). aisle's finished surface. Exception No. 2: Compartment doors used for access to a FPN: See 551.46(E). generator shall be pennitted to be equipped with a locking (C) Attachment Plugs. s>.•stem. (1) Units with One 15-Ampere Branch Circuit. Recre- (C) Dead-Front Type. The distribution panelboard shall ational vehicles having only one 15-ampere branch circuit be of the dead-front type and shall consist of one or more as permitted by 551.42(A) shall have an attachment plug circuit breakers or Type S fuseholders. A main disconnect- that shall be 2-pole, 3-wire grounding type, rated 15 am- ing means shall be provided where fuses are used or where peres, 125 volts, conforming to the configuration shown in more than two circuit breakers are employed. A main over- Figure 551.46(C) . current protective device not exceeding the power-supply assembly rating shall be provided where more than two FPN: Complete details of this configuration can be found in ANSi/NEMA WD 6-2002, National Electrical Manufac- turers Association's Standard far Dimensions ofituachment Plugs and Receptacle, Figure 5.15. 551.46 Means for Connecting to Power Supply. (2) Units with One 20-Ampere Branch Circuit. Recre- (A) Assembly. The power-supply assembly or assemblies ational vehicles having only one 20-ampere branch circuit as shall be factory supplied or factory installed and be of one permitted in 551.42(B) shall have an attachment plug that of the types specified herein. shall be 2-pole, 3-wire grounding type, rated 20 amperes, 74-480 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 551 —RECREATIONAL VEHICLES AND RECREATIONAL VEHICLE PARKS 551,47 Receptacles Caps made of etched, metal-stamped, or embossed brass, stain- less steel, or anodized or alclad aluminum not less than VG 1254,20-A,2-pole,3-wire, 0,51 mm (0.020 in.) thick, or other suitable material ]e.g., UG W 1 grounding type 0.13 mm (0.005 in.) thick plastic laminate] that reads, as � p W tG 125-V 15-A,2-pole,3-wire, appropriate, either 20-A,125-V WI grounding type THIS CONNECTION IS FOR 110-125-VOLT AC, 2-pole,3-wire, 60 HZ, AMPERE SUPPLY. grounding type or aG G THIS CONNECTION IS FOR 208Y/120-VOLT w or 1201240-VOLT AC, 3-POLE, 4-WIRE, 60 HZ, AMPERE SUPPLY. 30-A, 1254,2-pole,3-wire,grounding type The correct ampere rating shall be marked in the blank DG rG space. YD DX xl IY OW Iw (E) Location. The point of entrance of a power-supply as- sembly shall he located within 4.5 m(15 ft)of the rear,on the 50-A,125/250-V,3-pole,4-wire,grounding type left(road) side or at the rear, left of the longitudinal center of Figure 551.46(C) Configurations for Grounding-Type Recep- the vehicle, within 450 mm (18 in.) of the outside wall. tacles and Attachment Plug Caps Used For Recreational Ve- Exception No. 1: A recreational vehicle equipped with only hicle Supply Cords and Recreational Vehicle Lots. a listed flexible drain s.ystetn or a side-vent drain systenn shall be permitted to have the electrical paint of entrance 125 volts, conforming to the configuration shown in Fig- located on either side, provided the drain(s)for the plumb- ure 551.46(C). ing systenr is (are) located on the same side. FPN: Complete details or this configuration can be found Exception No. 2: A recreational vehicle shall be permitted in ANSUNEMA WD 6-2002,National Electrical Manufac- to have the electrical point of entrance located more than turers Association's Standard fnr Du»ension.r nfAttachnre'rt 4.5 to (15 ft),from the rear: Where this occurs, the distance Plugs and Receptacles, Figure 5.20. beyond the 4.5-in (15 ft) distension shall he added to the (3) Units with Two to Five 15- or 20-Ampere Branch cord's minimum length as specified in 551.46(B). Circuits. Recreational vehicles wired in accordance with Exception No. 3: Recreational vehicles desi{med for trans- 551.42(C) shall have an attachment plug that shall be porting livestock shall be permitted to have the electrical 2-pole, 3-wire grounding type, rated 30 amperes, 125 volts, point cif entrance located on either side or the front. conforming to the configuration shown in Figure 551.46(C), 551.47 Wiring Methods. intended for use with units rated at 30 amperes, 125 volts. (A) Wiring Systems. Cables in and raceways installed in ac- in A NSI/Complete details of this configuration can be found NF.MA WD 6-2(}02,National Electrical Manufac- cordance with Articles 320, 322, 330 through 340, 342 turers Association's Standard for Dimensions of Attachment through 362, 386, and 388 shall be permitted in accordance Plugs and Receptacles, Figure TT. with their applicable article, except as otherwise specified (4) Units with 50-Ampere Power-Supply Assembly. Rec- in this article.An equipment grounding means shall be pro- reational vehicles having a power-supply assembly rated 50 vided in accordance with 250.118. amperes as permitted by 551.42(D) shall have a 3-pole, (B) Conduit and `lbbing. Where rigid metal conduit or 4-wire grounding-type attachment plug rated 50 amperes, intermediate metal conduit is terminated at an enclosure 1251250 volts, conforming to the configuration shown in with a locknut and bushing connection, two locknuts shall Figure 551.46(C). be provided, one inside and one outside of the enclosure. All cut ends of conduit and tubing shall be reamed or oth- FPN: Complete details of this configuration can be found erwise finished to remove rough edges. in ANSI/NEMA WD 6-2002, National Electrical Manufac- turers Association's Standarcl fnr Dimensions ofAttachnnent (C) Nonmetallic Boxes. Nonmetallic boxes shall be ac- Plugs and Receptacles, Figure 14.50. ceptable only with nonmetallic-sheathed cable or nonmetal- (D) Labeling at Electrical Entrance. Each recreational lic raceways. vehicle shall have permanently affixed to the exterior skin, (D) Boxes. In walls and ceilings constructed of wood or at or near the point of entrance of the power-supply cord(s), other combustible material, boxes and fittings shall be flush a label 75 mm x 45 mm (3 in. x 1.114 in.) minimum size, with the finished surface or project therefrom. 2008 Edition NATIONAL ELECTRICAL CODE 70-481 551.47 ARTICLE 551—RECREATIONAL VEHICLES AND RECREATIONAL VEHICLE PARKS (E) Mounting.Wall and ceiling boxes shall be mounted in (M) Metal Faeeplates Grounded.Where metal faceplates accordance with Article 314, are used, they shall be grounded. Exception No. 1: Snap-in-type boxes or boxes provided (N) Moisture or Physical Damage. Where outdoor or with special wall or ceiling brackets that securely fasten under-chassis wiring is 120 volts, nominal, or over and is boxes in walls or ceilings shall be permitted. exposed to moisture or physical damage,the wiring shall be Exception No. 2: A wooden plate providing a 38-mm protected by rigid metal conduit, by intermediate metal (1112- in.) minimum width backing around the box and of conduit, or by electrical metallic tubing, rigid nonmetallic a thickness of 13 min (f/a in.) or greater(actual) attached conduit, or Type M1 cable, that is closely routed against directly to the wall panel shall be considered as ap- frames and equipment enclosures or other raceway or cable proved means for mounting outlet boxes. identified for the application. (F) Raceway and Cable Continuity.Raceways and cable (0) Component Interconnections. Fittings and connec- sheaths shall be continuous between boxes and other tors that are intended to be concealed at the time of assem- enclosures. bly shall be listed and identified for the interconnection of building components. Such fittings and connectors shall be (G) Protected. Metal-clad, Type AC, or nonmetallic- equal to the wiring method employed in insulation, tem- sheathed cables and electrical nonmetallic tubing shall be perature rise, and fault-current withstanding and shall be permitted to pass through the centers of the wide side of 2 capable of enduring the vibration and shock occurring in by 4 wood studs. However, they shall be protected where recreational vehicles. they pass through 2 by 2 wood studs or at other wood studs or frames where the cable or tubing would be less than (P) Method of Connecting Expandable Units. The 32 mm (1'/a in.) from the inside or outside surface. Steel method of connecting expandable units to the main body of plates on each side of the cable or tubing or a steel tube, the vehicle shall comply with 551.47(P)(1) or (P)(2): with not less than 1.35 mm (0.053 in.) wall thickness, shall (1) Cord-and-Plug-Connected. Cord-and-plug connec- be installed to protect the cable or tubing. These plates or tions shall comply with (a) through (d). tubes shall be securely held in place. Where nonmetallic- sheathed cables pass through punched, cut, or drilled slots (a) That portion of a branch circuit that is installed in or holes in metal members, the cable shall be protected by an expandable unit shall be permitted to be connected to the bushings or grommets securely fastened in the opening portion of the branch circuit in the main body of the vehicle prior to installation of the cable. by means of an attachment plug and cord listed for hard usage. The cord and its connections shall comply with all (H) Bends. No bend shall have a radius of less than five provisions of Article 400 and shall be considered as a per- times the cable diameter. milted use under 400.7. Where the attachment plug and cord are located within the vehicle's interior, use of plastic (I) Cable Supports. Where connected with cable connec- thermoset or elastomer parallel card Type SPT 3, SP-3, or tors or clamps, cables shall be supported within 300 mm (12 in.) of outlet boxes, distribution panelboards, and splice SPE shall be permitted. (b) Where the receptacle provided for connection of boxes on appliances. Supports shall be provided every 1.4 m the cord to the main circuit is located on the outside of the (4th ft) at other places. vehicle, it shall be protected with a ground-fault circuit (J) Nonmetallic Box Without Cable Clamps. Non- interrupter for personnel and be listed for wet locations. A metallic-sheathed cables shall be supported within 200 mm cord located on the outside of a vehicle shall be identified (8 in.) of a nonmetallic outlet box without cable clamps. for outdoor use. Where wiring devices with integral enclosures are em- (c) Unless removable or stored within the vehicle in- ployed with a loop of extra cable to permit future replace- terior, the cord assembly shall have permanent provisions ment of the device, the cable loop shall be considered as an for protection against corrosion and mechanical damage integral portion of the device. while the vehicle is in transit. (d) The attachment plug and cord shall be installed so (K) Physical Damage. Where subject to physical damage, as not to permit exposed live attachment plug pins. exposed nonmetallic cable shall be protected by covering boards, guard strips, raceways, or other means. (2) Direct Wired. That portion of a branch circuit that is installed in an expandable unit shall be permitted to be (L) Metal Faceplates. Metal faceplates shall be of ferrous connected to the portion of the branch circuit in the main metal not less than 0.76 mm (0.030 in.) in thickness or of body of the vehicle by means of flexible cord installed in nonferrous metal not less than 1.0 mm (0.040 in.) in thick- accordance with 551.47(P)(2)(a) through (P)(2)(e) or other ness. Nonmetallic faceplates shall be listed. approved wiring method. 70-482 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 551 —RFCRFATIONAL VEHICLES AND RECREATIONAL VEHICLE PARKS 551.47 (a) The flexible cord shall be listed for hard usage and (1) Circuit conductors shall be appropriately sized in rela- for use in wet locations, tion to the anticipated load and shall be protected by an (b) The flexible cord shall be permitted to be exposed overcurrent device in accordance with their ampacities. on the underside of the vehicle. Where the generator provides overcurrent protection (c) The flexible cord shall be permitted to pass through for the conductors, additional overcurrent protection is the interior of a wall or floor assembly or both a maximum not required. concealed length of 600 mm (24 in.) before terminating at (2) Where junction boxes are utilized at either of the cir- an outlet or junction box. cuit originating or terminus points, free ends of the (d) Where concealed, the flexible cord shall be in- conductors shall be adequately capped or taped. stalled in nonllexible conduit or tubing that is continuous (3) Where devices such as receptacle outlet, transfer from the outlet or junction box inside the recreational ve- switch, and so forth, are installed, the installation shall hide to a weatherproof outlet box, junction box, or strain be complete, including circuit conductor connections. relief fitting listed for use in wet locations that is located on All devices shall be listed and appropriately rated. the underside of the recreational vehicle. The outer jacket (4) A label conforming to 551.46(D) shall be placed on the of the flexible cord shall be continuous into the outlet or cover of each junction box containing incomplete cir- junction box. (e) Where the flexible cord passes through the floor to cuitry and shall read, as appropriate, either an exposed area inside of the recreational vehicle, it shall ONLY INSTALL A GENERATOR be protected by means of conduit and bushings or LISTED SPECIFICALLY FOR RV USE equivalent. GENERATOR CIRCUIT. THIS CONNECTION Where subject to physical damage, the flexible cord IS FOR GENERATORS RATED 110-125-VOLT AC, GO HZ, AMPERES MAXIMUM. shall be protected with RMC, IMC, Schedule 80 PVC, or other approved means and shall extend at least 150 mm or (6 in.) above the floor.A means shall be provided to secure ONLY INSTALL A GENERATOR LISTED the flexible cord where it enters the recreational vehicle. SPECIFICALLY FOR RV USE (Q) Prewiring for Air-Conditioning Installation. Prewir- GENERATOR CIRCUIT. THIS CONNECTION IS FOR GENERATORS RATED 120/240-VOLT AC, ing installed for the purpose of facilitating future air- 60 HZ, AMPERES MAXIMUM. conditioning installation shall comply with the applicable portions of this article and the following: The correct ampere rating shall be legibly marked in the (1) An overcurrent protective device with a rating compat- blank space. ible with the circuit conductors shall be installed in the (S) Prewiring for Other Circuits. Prewiring installed for distribution panelboard and wiring connections com- the purpose of installing other appliances or devices shall pleted. comply with the applicable portions of this article and the (2) The load end of the circuit shall terminate in a junction following: box with a blank cover or other listed enclosure. Where (l) An overcurrent protection device with a rating compatible a junction box with a blank cover is used, the free ends with the circuit conductors Shall be installed in the distd- of the conductors shall be adequately capped or taped. bution panelboard with wiring connections completed. (3) A label conforming to 551.46(D) shall be placed on or (2) The load end of the circuit shall terminate in a junction adjacent to the junction box and shall read as follows: box with a blank cover or a device listed for the pur- AIR-CONDITIONING CIRCUIT. pose. Where a junction box with blank cover is used, T141S CONNECTION IS FOR AIR CONDITIONERS the free ends of the conductors shall be adequately RATED 110-125-VOLT AC, 60 HZ, capped or taped. AMPERES MAXIMUM. (3) A label conforming to 551.46(D) shall be placed on or DO NOT EXCEED CIRCUIT RATING. adjacent to the junction box or device listed for the An ampere rating, not to exceed 80 percent of the purpose and shall read as follows: circuit rating, shall be legibly marked in the blank space. THIS CONNECTION IS FOR _ RATED (4) The circuit shall serve no other purpose. VOLT AC, 60 H4. AMPERES MAXIMUM. DO NOT EXCEED CIRCUIT RATING. (R) Prewiring for Generator Installation. Prewiring in- AN AMPERE RATING NOT TO EXCEED stalled for the purpose of facilitating future generator instal- 80 PERCENT OF THE CIRCUIT RATING lation shall comply with the other applicable portions of SHALL BE LEGIBLY MARKED this article and the following: IN THE BLANK SPACE. 2008 Edition NATIONAL ELECTRICAL CODE 70-483 551.48 ARTICLE 551—RECREATIONAL VEHICLES AND RECREATIONAL VEH tCLE PARKS 551.48 Conductors and Boxes. The maximum number of (C) Insulated Grounded Conductor. The grounded cir- conductors permitted in boxes shall be in accordance with cuit conductor shall be insulated from the equipment 314.16. grounding conductors and from equipment enclosures and other grounded parts. The grounded circuit conductor ter- 551.49 Grounded Conductors. The identification of minals in the distribution panelboard and in ranges, clothes grounded conductors shall be in accordance with 200.6. dryers, counter-mounted cooking units, and wall-mounted ovens shall be insulated from the equipment enclosure. 551.50 Connection of Terminals and Splices. Conductor Bonding screws, straps, or buses in the distribution panel- splices and connections at terminals shall be in accordance board or in appliances shall be removed and discarded. with 110.14. Connection of electric ranges and electric clothes dryers utilizing a grounded conductor, if cord-connected, shall be 551.51 Switches. made with 4-conductor cord and 3-pole, 4-wire grounding- (A) Rating. Switches shall be rated in accordance with type plug caps and receptacles. 551.51(A)(1) and (A)(2). 551.55 Interior Equipment Grounding. (1) Lighting Circuits. For lighting circuits, switches shall be rated not less than 10 amperes, 120-125 volts and in no (A) Exposed Metal Parts. In the electrical system, all ex- case less than the connected load. posed metal parts, enclosures, frames, luminaire canopies, and so forth, shall be effectively bonded to the grounding (2) Motors or Other Loads. Switches for motor or other terminals or enclosure of the distribution panelboard. loads shall comply with the provisions of 404.14. (B) Location. Switches shall not be installed within wet (B) Equipment Grounding and Bonding Conductors. Bare wires, insulated wire with an outer finish that is green locations in tub or shower spaces unless installed as part of or green with one or more yellow stripes, shall be used for a listed tub or shower assembly. equipment grounding or bonding conductors only. 551.52 Receptacles. All receptacle outlets shall be of the (C) Grounding of Electrical. Equipment. Grounding of grounding type and installed in accordance with 406.3 and electrical equipment shall be accomplished by one or more 210.21. of the following methods: 55153 Luminaires. (1) Connection of metal raceway, the sheath of Type MC and Type MI cable where the sheath is identified for (A) General. Any combustible wall or ceiling finish ex- grounding, or the armor of Type AC cable to metal posed between the edge of a luminaire canopy, or pan and enclosures. the outlet box, shall be covered with noncombustible mate- (2) A connection between the one or more equipment rial or a material identified for the purpose. grounding conductors and a metal enclosure by means of a grounding screw, which shall be used for no other (B) Shower Luminaires. If a Iuminaire is provided over a purpose, or a listed grounding device. bathtub or in a shower stall, it shall be of the enclosed and gasketed type and listed for the type of installation, and it (3) The equipment grounding conductor in nonmetallic- shall be ground-fault circuit-interrupter protected. sheathed cable shall be permitted to be secured under a screw threaded into the luminaire canopy other than a (C) Outdoor Outlets, Luminaires, Air-Cooling Equip- mounting screw or cover screw, or attached to a listed ment,and So On. Outdoor luminaires and other equipment grounding means (plate)in a nonmetallic outlet box for shall be listed for outdoor use, luminaire mounting. [Grounding means shall also be permitted for luminaire attachment screws.] 551.54 Grounding. (See also 551.56 on bonding of non- current-carrying metal parts.) (D) Grounding Connection in Nonmetallic Box. A con- nection between the one or more grounding conductors (A) Power-Supply Grounding. The grounding conductor brought into a nonmetallic outlet box shall be so arranged in the supply cord or feeder shall be connected to the that a connection can be made to any fitting or device in grounding bus or other approved grounding means in the that box that requires grounding. distribution panelboard. (E) Grounding Continuity. Where more than one equip- (B) Distribution Panelboard.The distribution panelboard ment grounding or bonding conductor of a branch circuit shall have a grounding bus with sufficient terminals for all enters a box, all such conductors shall be in good electrical grounding conductors or other approved grounding means. contact with each other, and the arrangement shall be such 70-484 NATIONAL ELECTRICAL CODE 2WH Edition ARTICLE 551 —RECREATIONAL VEHICLES AND RECREATIONAL.VEHICLE PARKS 551.71 that the disconnection or removal of a receptacle, lumi- tion. Means shall be provided to securely fasten appliances naire, or other device fed from the box will not interfere in place when the recreational vehicle is in transit. with or interrupt the grounding continuity. (F) Cord-Connected Appliances. Cord-connected appli- V. Factory Tests ances, such as washing machines, clothes dryers, refrigera- 551.60 Factory Tests (Electrical). Each recreational ve- tors, and the electrical system of gas ranges, and so forth, hicle designed with a 120-volt or a 120/240-volt electrical shall be grounded by means of an approved cord with system shall withstand the applied potential without electri- equipment grounding conductor and grounding-type attach- cal breakdown of a 1-minute, 900-volt ac or 1280-volt de attach- ment plug. dielectric strength test, or a 1-second, 1080-volt ac or 1530- 551.56 Bonding of Non—Current-Carrying Metal Parts. volt do dielectric strength test, with all switches closed, between ungrounded and grounded conductors and the rec- (A) Required Bonding. All exposed non—current-carrying reational vehicle ground. During the test, all switches and metal parts that may become energized shall be effectively other controls shall be in the "on" position. Fixtures, in- bonded to the grounding terminal or enclosure of the dis- eluding luminaires and permanently installed appliances, tribution panelboard. shall not be required to withstand this test. The test shall be performed after branch circuits are complete prior to ener- {B} Bonding Chassis. A bonding conductor shall be con- gi7ing the system and again after all outer coverings and nected between any distribution panelboard and an accessible cabinetry have been secured. terminal an the chassis. Aluminum or copper-clad aluminum Each recreational vehicle shall be subjected to all of the conductors shall not be used for banding if such conductors or following: their terminals are exposed to corrosive elements. (1) A continuity test to ensure that all metal parts are prop- Exception: Anv recreational vehicle that employs a unit- erly bonded ized metal chassis frame construction to which the distri- (2) Operational tests to demonstrate that all equipment is bution panelboard is securel-v itstened with a bolt(s) and properly connected and in working order nut(s) or hti• welding or riveting shall be considered to be handed. (3) Polarity checks to determine that connections have been properly made (C) Bonding Conductor Requirements. Grounding ter- (4) GFCI test to demonstrate that the ground fault protec- minals shall be of the solderless type and listed as pressure tion device(s) installed on the recreational vehicle are terminal connectors recognized for the wire size used. The operating properly. bonding conductor shall be solid or stranded, insulated or bare, and shall be 8 AWG copper minimum, or equal. VI. Recreational Vehicle Parks (D) Metallic Roof and Exterior Bonding.The metal roof 551.71 Type Receptacles Provided. Every recreational and exterior covering shall be considered bonded where vehicle site with electrical supply shall be equipped with at both of the following conditions apply: least one 20-ampere, 125-volt receptacle. A minimum of (1) The metal panels overlap one another and are securely 20 percent of all recreational vehicle sites, with electrical attached to the wood or metal frame parts by metal supply, shall each be equipped with a 50-ampere, 125/250- fasteners. volt receptacle conforming to the configuration as identified (2) The lower panel of the metal exterior covering is se- in Figure 551.46(C) .These electrical supplies shall be per- cured by metal fasteners at each cross member of the mitted to include additional receptacles that have configu- chassis, or the lower panel is connected to the chassis rations in accordance with 551.81. A minimum of 70 per- by a metal strap. cent of all recreational vehicle sites with electrical supply shall each be equipped with a 30-ampere, 125-volt recep- (E) Gas, Water, and Waste Pipe Bonding. The gas, wa- tacfe conforming to Figure 551.46(C) .This supply shall be ter, and waste pipes shall be considered grounded if they permitted to include additional receptacle configurations are bonded to the chassis. conforming to 551.81. The remainder of all recreational (F) Furnace and Metal Air Duct Bonding. Furnace and vehicle sites with electrical supply shall be equipped with metal circulating air ducts shall be bonded. one or more of the receptacle configurations conforming to 551.81. Dedicated tent sites with a 15- or 20-ampere elec- 551.57 Appliance Accessibility and Fastening. Every ap- trical supply shall be permitted to be excluded when deter- pliance shall be accessible for inspection, service, repair, mining the percentage of recreational vehicle sites with 30- and replacement without removal of permanent construe- or 50-ampere receptacles. 2008 Edition NATIONAL ELECTRICAL CODE 70-485 551.72 ARTICLE 551—RECREATIONAL VEHICLES AND RECREATIONAL VEHICLE PARKS Additional receptacles shall be permitted for the con- Table 551.73 Demand Factors for Site Feeders and nection of electrical equipment outside the recreational ve- Service-Entrance Conductors for Park Sites hicle within the recreational vehicle park. All 125-volt, single-phase, 15- and 20-ampere recep- Number of Recreational Demand Factor tacles shall have listed ground-fault circuit-interrupter pro- Vehicle Sites (%) tection for personnel. 1 100 FPN: The percentage of 50 ampere sites required by 2 90 3 8U 551.71 may he inadequate for seasonal recreational vehicle 4 75 sites serving a higher percentage of recreational vehicles 65 with 50 ampere electrical systems. In that type of recre- 5 5 60 ational vehicle park, the percentage of 50 ampere sites 7-9 55 could approach 100 percent. 10-12 50 System. Receptacles rated at 50 am- 13-15 48 551.72 Distribution S Y p 16-18 47 peres shall be supplied from a branch circuit of the voltage 19--21 45 class and rating of the receptacle. Other recreational vehicle 22--24 43 sites with 125-volt, 20- and 30-ampere receptacles shall be 25-35 42 permitted to be derived from any grounded distribution sys- 36 plus 41 tem that supplies 120-volt single-phase power. The neutral conductors shall not be reduced in size below the size of sults in a permissible demand of 1620 volt-amperes per site the ungrounded conductors for the site distribution. The or a total of 32,400 volt-amperes for 20 sites. neutral conductors shall be permitted to be reduced in size below the minimum required size of the ungrounded con- FPN: These demand factors may be inadequate in areas of extreme hat or cold temperature with loaded circuits for ductors for 240-volt, line-to-line, permanently connected heating or air conditioning, loads only. (D) Feeder-Circuit Capacity. Recreational vehicle site 551.73 Calculated Load. feeder-circuit conductors shall have an ampacity not less (A) Basis of Calculations. Electrical services and feeders than the Ioads supplied and shall be rated not less than 30 shall be calculated on the basis of not less than 9600 volt- amperes.The neutral conductors shall have an ampacity not amperes per site equipped with 50-ampere, 208Y/120 or less than the ungrounded conductor's. 1201240-volt supply facilities; 3600 volt-amperes per site FPN: Due to the long circuit lengths typical in most recre- equipped with both 20-ampere and 30-ampere supply fa- ational vehicle parks, feeder conductor sizes found in the ampacity tables of Article 310 may be inadequate to main- cilities; 2400 volt-amperes per site equipped with only 20- tain the voltage regulation suggested in the line print note ampere supply facilities; and 600 volt-amperes per site to 210.19.Total circuit voltage drop is a sum of the voltage equipped with only 20-ampere supply facilities that are drops of each serial circuit segment, where the load for dedicated to tent sites. The demand factors set forth in each segment is calculated using the load that segment sees Table 551.73 shall be the minimum allowable demand fac- and the demand factors of 551.73(A). tors that shall be permitted in calculating load for service Loads for other amenities such as, but not limited to, and feeders. Where the electrical supply for a recreational service buildings, recreational buildings, and swimming vehicle site has more than one receptacle, the calculated pools shall be calculated separately and then be added to load shall be calculated only for the highest rated recep- the value calculated for the recreational vehicle sites where tacle. they are all supplied by a common service. Where the electrical supply is in a location that serves two recreational vehicles, the equipment for both sites sball 551.74 Overcurrent Protection. Overcurrent protection comply with 551.77 and the calculated load shall only be shall be provided in accordance with Article 240. computed for the two receptacles with the highest rating. 551.75 Grounding. All electrical equipment and installa- (B) Transformers and Secondary Distribution Panel- tions in recreational vehicle arks shall be boards. For the purpose of this Code, where the ark ser- p grounded as p � p required by Article 250. vice exceeds 240 volts, transformers and secondary distri- bution panelboards shall be treated as services. 551.76 Grounding — Recreational Vehicle Site Supply (C) Demand Factors.The demand factor for a given num- Equipment. ber of sites shall apply to all sites indicated. For example, (A) Exposed Non-Current-Carrying Metal Parts. Ex- 20 sites calculated at 45 percent of 3600 volt-amperes re- posed non-current-carrying metal parts of fixed equipment, 70-486 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 551 —RECREATIONAL VEHICLES AND RECREATIONAL VEHICLE PARKS 551.80 metal boxes, cabinets, and fittings that are not electrically (E) Working Space. Sufficient space shall be provided and connected to grounded equipment shall be grounded by an maintained about all electrical equipment to permit ready equipment grounding conductor run with the circuit con- and safe operation, in accordance with 110.26. ductors from the service equipment or from the transformer of a secondary distribution system. Equipment grounding (F) Marking. Where the site supply equipment contains a conductors shall be sized in accordance with 250.122 and 1251250-volt receptacle, the equipment shall be marked as shall be permitted to be spliced by listed means. follows: "Turn disconnecting switch or circuit breaker off The arrangement of equipment grounding connections before inserting or removing plug. Plug must be fully in- shall be such that the disconnection or removal of a recep- serted or removed," The marking shall be located on the tacle or other device will not interfere with, or interrupt, the equipment adjacent to the receptacle outlet. grounding continuity. 551.78 Protection of Outdoor Equipment. (B) Secondary Distribution System. Each secondary dis- tribution system shall be grounded at the transformer. (A) Wet Locations, All switches, circuit breakers, recep- tacles, control equipment, and metering devices located in (C) Grounded Conductor Not to Be Used as an Equip- wet locations shall be weatherproof. ment Ground. The grounded conductor shall not be used as an equipment grounding conductor for recreational ve- (B) Meters. If secondary meters are installed, meter sock- hicles or equipment within the recreational vehicle park, ets without meters installed shall be blanked off' with an approved blanking plate. (D) No Connection on the Load Side. No connection to a grounding electrode shall be made to the grounded conduc- 551.79 CIearance for Overhead Conductors. Open con- tor on the load side of the service disconnecting means ductors of not over 600 volts, nominal, shall have a vertical except as covered in 250.30(A) for separately derived sys- clearance of not less than 5.5 m (18 ft) and a horizontal tems, and 250.32(B) Exception for separate buildings. clearance of not less than 900 mm (3 ft) in all areas subject to recreational vehicle movement. In all other areas, clear- 551.77 Recreational Vehicle Site Supply Equipment. ances shall conform to 225.18 and 225.19. (A) Location. Where provided on back-in sites, the recre- FPN: For clearances of conductors over 600 volts, nomi- ational vehicle site electrical supply equipment shall be lo- nal, see 225.60 and 225.61. cated on the left(road) side of the parked vehicle, on a line that is 1.5 m to 2.1 m (5 ft to 7 ft) from the left edge 551,80 Underground Service, Feeder, Branch-Circuit, (driver's side of the parked RV) of the stand and shall be and Recreational Vehicle Site Feeder-Circuit Conductors. located at any point on this line from the rear of the stand to 4.5 m (15 ft) forward of the rear of the stand. (A) General. All direct-burial conductors, including the For pull-through sites, the electrical supply equipment equipment grounding conductor if of aluminum, shall be shall be permitted to be located at any point along the line insulated and identified for the use, All conductors shall be that is 1.5 m to 2.1 m (5 ft to 7 ft) from the left edge continuous from equipment to equipment. All splices and (driver's side of the parked RV)from 4.9 in(16 ft) forward of taps shall be made in approved junction boxes or by use of the rear of the stand to the center point between the two roads material listed and identified for the purpose. that gives access to and egress from the pull-through sites. The left edge (driver's side of the parked RV) of the (B) Protection Against Physical Damage. Direct-buried stand shall be marked, conductors and cables entering or leaving a trench shall be protected by rigid metal conduit, intermediate metal con- (B) Disconnecting Means.A disconnecting switch or cir- duit, electrical metallic tubing with supplementary corro- cuit breaker shall be provided in the site supply equip- sion protection, rigid nonmetallic conduit, liquidtight flex- ment for disconnecting the power supply to the recre- ible nonmetallic conduit, liquidtight flexible metal conduit, ational vehicle. or other approved raceways or enclosures.Where subject to physical damage, the conductors or cables shall be pro- (C) Access. All site supply equipment shall be accessible tected by rigid metal conduit, intermediate metal conduit, by an unobstructed entrance or passageway not less than or Schedule 80 PVC conduit, All such protection shall ex- 600 mm (2 ft) wide and 2.0 m (6 ft 6 in.) high. tend at least 450 mm (18 in.) into the trench from finished (D) Mounting Height. Site supply equipment shall be lo- grade. cated not less than 600 mm (2 ft) or more than 2.0 m (6 ft FPN: See 300.5 and Article 340 for conductors or Type OF 6 in.) above the ground. cable used underground or in direct burial in earth. 2008 Edition NATIONAL ELECTRICAL CODE 70-487 551.81 ARTICLE 552—PARK TRAILERS 551.81 Receptacles. A receptacle to supply electric power Exception: A metal chassis or frame shall be permitted as to a recreational vehicle shall be one of the configurations the return path to the source of supply. shown in Figure 551.46(C) in the following ratings: ( (2) Conductor Types. Conductors shall conform to the re- (1)} 50-ampere — 1251250-volt, 50-ampere, 3-pole, 4-wire quirements for Type GXL, HDT, SGT, SGR, or Type SXL grounding type for 1201240-volt systems or shall have insulation in accordance with Table 310.13(A) (2) 30-ampere — 125-volt, 30-ampere, 2-pole, 3-wire or the equivalent.Conductor sizes 6 AWG through 18 AWG grounding type for 120-volt systems or SAE shall be listed. Single-wire, low-voltage conductors (3) 20-ampere -- 125-volt, 20-ampere, 2-pale, 3-wire shall be of the stranded type. grounding type for 120-volt systems FPN: See SAE Standard J 1128-1995 for Types GXL,HDT, FPN: Complete details of these configurations can be found and SXL and SAE Standard J 1127-1995 For Types SGT and in ANSUNEMA WD 6-2002,National Electrical Manufactur- SGR. ers Association's Standard for Dimensions of Attachment Plugs and Receptacles, Figures 1450,TT and 5-20. (3) Marking. All insulated tow-voltage conductors shall be surface marked at intervals not greater than 1.2 m (4 ft) as follows: (1) Listed conductors shall be marked as required by the listing agency. ARTICLE 552 (2) SAE conductors shall be marked with the name or logo Park Trailers of the manufacturer, specification designation,and wire gauge. 1. General (3) Other conductors shall be marked with the name or logo of the manufacturer,temperature rating, wire gauge, 552.1 Scope. The provisions of this article cover the elec- conductor material, and insulation thickness. trical conductors and equipment installed within or on park trailers not covered fully under Articles 550 and 551. (C) Low-Voltage Wiring Methods. 552.2 Definition. (See Articles 100, 550, and 551 for ad- (1) Physical Protection. Conductors shall be protected against physical damage and shall be secured. Where insu- lated conductors are clamped to the structure, the conductor Park Trailer. A unit that is built on a single chassis insulation shall be supplemented by an additional wrap or mounted on wheels and has a gross trailer area not exceed- layer of equivalent material, except that jacketed cables shall ing 37 m2 (400 ft2) in the set-up mode. not be required to be so protected.Wiring shall be routed away from sharp edges, moving parts, or heat sources. 552.3 Other Articles. Wherever the provisions of other articles and Article 552 differ, the provisions of Article 552 (2) Splices. Conductors shall be spliced or joined with shall apply. splicing devices that provide a secure connection or by PP y brazing, welding, or soldering with a fusible metal or alloy. 552.4 General Requirements. A park trailer as specified Soldered splices shall first be spliced or joined to be me- in 552.2 is intended for seasonal use. It is not intended as a chanically and electrically secure without solder, and then permanent dwelling unit or for commercial uses such as soldered. All splices, joints, and free ends of conductors banks, clinics, offices, or similar. shall be covered with an insulation equivalent to that on the conductors. II. Low-Voltage Systems (3) Separation. Battery and other low-voltage circuits shall be physically separated by at least a 13-mm (t/2-in.) 552.10 Low-Voltage Systems. gap or other approved means from circuits of a different (A) Low-Voltage Circuits. Low-voltage circuits furnished power source. Acceptable methods shall be by clamping, and installed by the park trailer manufacturer,other than those routing, or equivalent means that ensure permanent total related to braking,are subject to this Code.Circuits supplying separation. Where circuits of different power sources cross, lights subject to federal or state regulations shall comply with the external jacket of the nonmetallic-sheathed cables shall applicable government regulations and this Code. be deemed adequate separation. (B) Low-Voltage Wiring. (4) Ground Connections. Ground connections to the chassis or frame shall be made in an accessible location and (1) Material. Copper conductors shall be used for low- shall be mechanically secure. Ground connections shall be voltage circuits. by means of copper conductors and copper or copper-alloy 70-488 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 552—PARK TRAILERS 552.20 terminals of the solderless type identified for the size of shall be installed in accordance with the manufacturer's wire used. The surface on which ground terminals make con- instructions. tact shall be cleaned and he free from oxide or paint or shall be Motors that are controlled by automatic switching or by electrically connected through the use of a cadmium, tin, or latching-type manual switches shall be protected in accor- zinc-plated internal/extemal-toothed lockwasher or locking dance with 430.32(B). terminals. Ground terminal attaching screws, rivets or bolts, (4) Location. The overcurrent protective device shalt be nuts, and lockwashers shall be cadmium, tin, or zinc-plated except rivets shall be permitted to be unanodized aluminum installed in an accessible location on the unit within 450 mm (18 in.) of the point where the power supply con- where attaching to aluminum structures, netts to the unit circuits. If located outside the park trailer, The chassis-grounding terminal of the battery shall be the device shall be protected against weather and physical connected to the unit chassis with a minimum 8 AWG cop- per conductor. In the event the unbonded lead from the damage. battery exceeds 8 AWG, the bonding conductor size shall Exception: External low-voltage supphv shall be permitted be not less than that of the unbonded lead. to have the overcurrent protective device within 450 mm (18 in.) after entering the unit or after leaving a metal (D) Battery Installations. Storage batteries subject to the raceway. provisions of this Code shall be securely attached to the unit and installed in an area vaportight to the interior and (F) Switches. Switches shall have a do rating not less than ventilated directly to the exterior of the unit. Where batter- the connected load, ies are installed in a compartment, the compartment shall be ventilated with openings having a minimum area of (G) Luminaires. All low-voltage interior luminaires rated 1 100 mm (1.7 in.`) at both the top and at the bottom. more than 4 watts, employing lamps rated more than 1.2 Where compartment doors are equipped for ventilation, the watts, shall be listed. openings shall be within 50 mm (2 in.) of the top and bottom. Batteries shall not be installed in a compartment 11I11. Combination Electrical Systems containing spark- or flame-producing equipment. 552.20 Combination Electrical Systems. (E) overcurrent Protection. (A) General. Unit wiring suitable for connection to a bat- (1) Rating. Low-voltage circuit wiring shall be protected tery or other law-voltage supply source shall be permitted by overcurrent protective devices rated not in excess of to be connected to a 120-volt source, provided that the the ampacity of copper conductors, in accordance with entire wiring system and equipment are rated and installed Table 552.10(E)(1}, in full conformity with Parts I, II1, IV, and V requirements Of this article covering 120-volt electrical systems. Circuits Table 552.10(E)(1) Low-Voltage overcurrent Protection fed from ac transformers shall not supply de appliances. Wire Size (AWG) Ampacity Wire'l-pe (B) Voltage Converters (120-Volt Alternating Current to Low-Voltage Direct Current). The 120-volt ac side of 18 h Stranded only the voltage converter shall be wired in full conformity with 16 8 Stranded only parts I, III, IV, and V requirements of this article for 120- 14 15 Stranded or solid 12 20 Stranded or solid volt electrical systems. 10 30 Stranded or solid Exception: Converters supplied as an integral part of a listed appliance .shall not be .subject to 552.20(B). (2) Type.Circuit breakers or fuses shall be of an approved All converters and transformers shall be listed for use in type, including automotive types. Fuseholders shall be recreation units and designed or equipped to provide aver- clearly marked with maximum fuse size and shall be pro- temperature protection. To determine the converter rating, tected against shorting and physical damage by a cover or the following formula shall be applied to the total con- equivalent means. netted load, including average battery charging rate, of all FPN: For further information, see ANSIISAE J554-1987, 12-volt equipment: Standard for Electric Fuser (Cartridge Tipe): SAE J1284- The first 20 amperes of load at 100 percent; plus 1988,Standard.for Blade 7:ype Electric Fuses;and UL 275- The second 20 amperes of load at 50 percent; plus 1993, Standard for Automolire Glass Tube Fuses. All load above 40 amperes at 25 percent (3) Appliances. Appliances such as pumps, compressors, Exception: A low-roltage appliance that is controlled by a heater blowers, and similar motor-driven appliances tnotnentary snitch (normally open) that has no means for 2008 Edition NATIONAL ELECTRICAL CODE 70-489 552.40 ARTICLE 552—PARK TRAILERS holding in the closed position shall not be considered as a (B) Location. Receptacle outlets shall be installed as connected load when determining the required converter follows: rating. Momentarily energized appliances shall be limited (1) Adjacent to countertops in the kitchen [at least one on to those used to prepare the unit for occupancy or travel. each side of the sink if countertops are on each side and (C) Bonding Voltage Converter Enclosures. The non— are 300 mm (12 in.) or over in width] current-carrying metal enclosure of the voltage converter (2) Adjacent to the refrigerator and gas range space,except shall be connected to the frame of the unit with an 8 AWG where a gas-fired refrigerator or cooking appliance, re- copper conductor minimum. The grounding conductor for quiring no external electrical connection, is factory- the battery and the metal enclosure shall be permitted to be installed the same conductor. (3) Adjacent to countertop spaces of 300 mm (12 in.) or ( more in width that cannot be reached from a receptacle D) Dual-Voltage Fixtures Including Luminaires or Ap- required in 552.41(B)(1)by a cord of 1.8 m(6 ft)without pliances.Fixtures, including luminaires, or appliances hav- crossing a traffic area, cooking appliance, or sink ing both 120-volt and low-voltage connections shall be listed for dual voltage. (C) Ground-Fault Circuit-Interrupter Protection. Each (E) Autotransformers. Autotransformers shall not be used. 125-volt, single-phase, 15- or 20-ampere receptacle shall have ground-fault circuit-interrupter protection for person- (F) Receptacles and Plug Caps. Where a park trailer is nel in the following locations: equipped with a 120-volt or 1201240-volt ac system, a low- (1) Where the receptacles are installed to serve kitchen voltage system, or both, receptacles and plug caps of the countertop surfaces low-voltage system shall differ in configuration from those (2) Within 1.8 m (6 ft) of any lavatory or sink of the 120-volt or 1201240-volt system. Where a unit equipped with a battery or do system has an external con- Exception: Receptacles installed for appliances in dedi- nection for low-voltage power, the connector shall have a cated spaces, such as for dishwashers, disposals, refrigera- configuration that will not accept 120-volt power. tors,freezers, and laundry equipment. (3) In the area occupied by a toilet, shower, tub, or any IV. Nominal 120-Volt or 1201240-Volt Systems combination thereof 552.40 120-Volt or 1201240-Volt, Nominal, Systems. (4) On the exterior of the unit (A) General Requirements. The electrical equipment and Exception: Receptacles that are located inside of an access material of park trailers indicated for connection to a wiring panel that is installed on the exterior of the unit to supply system rated 120 volts, nominal, 2-wire with an equipment power for an installed appliance shall not be required to grounding conductor, or a wiring system rated 1201240 have ground fault circuit-interrupter protection. volts, nominal, 3-wire with an equipment grounding con- The receptacle outlet shall be permitted in a listed lu- ductor, shall be listed and installed in accordance with the minaire.A receptacle outlet shall not be installed in a tub or requirements of Parts I, III, IV, and V of this article. combination tub—shower compartment. (B) Materials and Equipment. Electrical materials, de- (D) Pip e Heating Cable Outlet. Where a pipe heating vices, appliances, fittings, and other equipment installed, cable outlet is installed, the outlet shall be as follows: intended for use in, or attached to the park trailer shall be (1) Located within 600 mm (2 ft) of the cold water inlet listed. All products shall be used only in the manner in which they have been tested and found suitable for the (2) Connected to an interior branch circuit, other than a intended use. small-appliance branch circuit (3) On a circuit where all of the outlets are on the load side 552.41 Receptacle Outlets Required. of the ground-fault circuit-interrupter protection for (A) Spacing. Receptacle outlets shall be installed at wall personnel spaces 600 mm (2 ft) wide or more so that no point along (4) Mounted on the underside of the park trailer and shall the floor line is more than 1.8 m (6 ft), measured horizon- not be considered to be the outdoor receptacle outlet tally, from an outlet in that space. required in 552.41(E) Exception No. 1: Bath and hall areas. (E) Outdoor Receptacle Outlets. At least one receptacle Exception No. 2: Wall spaces occupied by kitchen cabinets, outlet shall be installed outdoors. A receptacle outlet lo- wardrobe cabinets, built-in furniture; behind doors that cated in a compartment accessible from the outside of the may open fully against a wall surface; or similar facilities. park trailer shall be considered an outdoor receptacle. Out- 70-490 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 552—PARK TRAILERS 552,44 door receptacle outlets shall be protected as required in directly to the terminals of the distribution panelboard or con- 552.41(C)(4). ductors within a junction box and provided with means to prevent strain from being transmitted to the terminals. The (F} Receptacle Outlets Not Permitted. ampacity of the conductors between each junction box and the (1) Shower or Bathtub Space. Receptacle outlets shall terminals of each distribution panelboard shall be at least not be installed in or within reach [750 mm (30 in.)] of a equal to the ampacity of the power-supply cord. The supply shower or bathtub space. end of the assembly shall be equipped with an attachment plug (2) Face-Up Position.A receptacle shall not be installed in of the type described in 552.44(C). Where the cord passes a face-up position in any countertop. through the walls or floors, it shall be protected by means of conduit and bushings or equivalent. The cord assembly shall 552.43 Power Supply. have permanent provisions for protection against corrosion (A) Feeder.The power supply to the park trailer shall be a and mechanical damage while the unit is in transit. feeder assembly consisting of not more than one listed 30- ampere or 50-ampere park trailer power-supply card with (B) Cord Length.The cord-exposed usable length shall be an integrally molded or securely attached cap, or a perma- measured from the point of entrance to the park trailer or the face of the flanged surface inlet (motor-base attachment nently installed feeder. plug) to the face of the attachment plug at the supply end. (B) Power-Supply Cord. If the park trailer has a power- The cord-exposed usable length, measured to the point supply cord, it shall be permanently attached to the distri- of entry on the unit exterior, shall be a minimum of 7.0 m bution panelboard or to a junction box permanently con- (23 ft) where the point of entrance is at the side of the unit, nected to the distribution panelboard, with the free end or shall be a minimum 8.5 m (28 ft) where the point of terminating in a molded-on attachment plug cap. entrance is at the rear of the unit. The maximum length Cords with adapters and pigtail ends, extension cords, shall not exceed I1 m (361/2 ft). and similar items shall not be attached to, or shipped with, Where the cord entrance into the unit is more than a park trailer. 900 mm(3 ft)above the ground, the minimum cord lengths A suitable clamp or the equivalent shall be provided at above shall be increased by the vertical distance of the cord the distribution panelboard knockout to afford strain relief entrance heights above 900 mm (3 fty for the cord to prevent strain from being transmitted to the terminals when the power-supply cord is handled in its (C) Attachment Plugs. intended manner. (1) Units with Two to Five 15- or 20-Ampere Branch The cord shall be a listed type with 3-wire, 120-volt or Circuits. Park trailers wired in accordance with 552.46(A) 4-wire, 1201240-volt conductors, one of which shall be shall have an attachment plug that shall be 2-pole, 3-wire identified by a continuous green color or a continuous grounding-type, rated 30 amperes, 125 volts, conforming to green color with one or more yellow stripes for use as the the configuration shown in Figure 552.44(C) intended for grounding conductor. use with units rated at 30 amperes, 125 volts. (C) Mast Weatherhead or Raceway. Where the calcu- FPN: Complete details or this configuration can he found lated load exceeds 50 amperes or where a permanent in ANSI/NEMA WD 6-1989,National Electrical Manufac- feeder is used, the supply shall be by means of one of the turers Association's Standard for Dimensions of Attachment following: Plugs and Receptacles, Figure TT (1) One mast weatherhead installation, installed in accor- (2) Units with 50-Ampere Power Supply Assembly.Park dance with Article 230, containing four continuous, in- trailers having a power-supply assembly rated 50 amperes sulated, color-coded feeder conductors, one of which as permitted by 552.43(B) shall have a 3-pole, 4-wire shall be an equipment grounding conductor grounding-type attachment plug rated 50 amperes, 1251250 (2) A metal raceway, rigid nonmetallic conduit, or liq- volts, conforming to the configuration shown in Figure uidtight flexible nonmetallic conduit from the discos- 552.44(C). netting means in the park trailer to the underside of the park trailer, with provisions for the attachment to a FPN: Complete details of this configuration can be found suitable junction box or fitting to the raceway on the in ANSU/NEMA WD 6-1989, National Electrical Manufac- turers Association Standard,fnr Dimensintts nfAttachment underside of the park trailer [with or without conduc- Plugs and Receptacles, Figure 14-50. tors as in 550.10(I)(1)j (D) Labeling at Electrical Entrance. Each park trailer 552.44 Cord. shall have permanently affixed to the exterior skin, at or (A) Permanently Connected.Each power-supply assembly near the point of entrance of the power-supply assembly, a shall be factory supplied or factory installed and connected label 75 mm x 45 mm (3 in. x 11/4 in.) minimum size, made 2008 Edition NATIONAL ELECTRICAL CODE 70-491 552.45 ARTICLE 552—PARK TRAILERS Receptacles Caps Exception: Where the panelboard cover is exposed to the vG inside aisle space, one of the working clearance dimensions r ' shall be permitted to be reduced to a minimum of 550 mm W W (22 in.). A panelboard shall be considered exposed where the panelboard cover is within 50 mm (2 in.) of the aisle's 30-A,125-V,2 pole,3 wire,grounding type finished surface. Q� �G (C) Dead-Front Type. The distribution panelboard shall YQ QX X[ �Y be of the dead-front type.A main disconnecting means shall Qw W be provided where fuses are used or where more than two 50-A,1251250-V,3-pale,4-wire,grounding type circuit breakers are employed. A main overcurrent protec- tive device not exceeding the power-supply assembly rating Figure 552.44(C) Attachment Cap and Receptacle shall be provided where more than two branch circuits are Configurations. employed. of etched, metal-stamped, or embossed brass, stainless 552.46 Branch Circuits. Branch circuits shall be deter- steel, or anodized or alclad aluminum not less than mined in accordance with 552.46(A) and (B). 0.51 mm (0.020 in.) thick, or other suitable material [e.g., 0.13 mm (0.005 in.) thick plastic laminate], that reads, as (A) Two to Five 15- or 20-Ampere Circuits. Two to five appropriate, either 15- or 20-ampere circuits to supply lights, receptacle out- lets, and fixed appliances shall be permitted. Stich park THIS CONNECTION IS FOR 110–)25-VOLT AC, trailers shall be equipped with a distribution panelboard 60 HZ, 30 AMPERE SUPPLY rated at 120 volts maximum with a 30-ampere rated main or power supply assembly. Not more than two 120-volt ther- mostatically controlled appliances (e.g., air conditioner and THIS CONNECTION IS FOR 208Y1120-VOLT water heater) shall be installed in such systems unless ap- OR 1201240-VOLT AC, 3-POLE, 4-WIRE, pliance isolation switching, energy management systems, 60 HZ, AMPERE SUPPLY. or similar methods are used. The correct ampere rating shall be marked in the blank Exception: Additional 15- or 20-ampere circuits shall be space. permitted where a listed energy management system rated (E) Location. The point of entrance of apower-supply at 30 amperes maximum is employed within the system. assembly shall be located within 4.5 m (15 ft) of the rear, (B) More Than Five Circuits. Where more than five cir- on the left (road) side or at the rear, left of the longitudinal cuits are needed, they shall be determined in accordance center of the unit, within 450 mm (18 in.) of the outside with 552.46(B)(1), (B)(2), and (13)(3). wall. E (1) Lighting.Based on 33 volt-amperes/m2(3 VA/ftz)mul- xception: A park trailer shall be permitted to have the tiplied by the outside dimensions of the park trailer (coupler electrical point of entrance located more than 4.5 nn (15 ft) excluded)divided by 120 volts to determine the number of 15- from the rear. Where this occurs, the distance beyond the or 20-ampere lighting area circuits, for example, 4.5-m (15 ft) dimension shall be added to the cord's mini- mum length as specified in 551.46(B). 3 x length x width 120 x 15 (or 20) 552.45 Distribution Panelboard. No,of 15– (or 20–) ampere circuits (A) Listed and Appropriately Rated. A Iisted and appro- The lighting circuits shall be permitted to serve built-in priately rated distribution panelboard shall be used. The grounded conductor termination bar shall be insulated from gas ovens with electric service only for lights, clocks or the enclosure as provided in 552.55(C). An equipment timers, or listed cord-connected garbage disposal units. grounding terminal bar shall he attached inside the metal (2) Small Appliances. Small-appliance branch circuits enclosure of the panelboard, shall be installed in accordance with 210.11(C)(1). (B) Location. The distribution panelboard shall be in- (3) General Appliances. (including furnace, water heater, stalled in a readily accessible location. Working clearance space heater, range, and central or room air conditioner, for the panelboard shall be not less than 600 mm (24 in.) etc.)An individual branch circuit shall be permitted to sup- wide and 750 mm (30 in.) deep, ply any load for which it is rated. There shall be one or 70-492 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 552—PARK TRAILERS 552.48 more circuits of adequate rating in accordance with (a) except include blower motor if used as air-conditioner through (d). evaporator motor. Where an air conditioner is not in- stalled and a 50-ampere power-supply cord is provided, FPN No. I: For the laundry branch circuit,see_10.11(C)( ). allow 15 amperes per phase for air conditioning. FPN No. 2: For central air conditioning, see Article 440. (3) Twenty-five percent of current of largest motor in (a) The total rating of fixed appliances shall not exceed (13)(2). 50 percent of the circuit rating if lighting outlets, general- (4) Total of nameplate amperes for disposal, dishwasher, use receptacles, or both are also supplied, water heater, clothes dryer, wall-mounted oven, cook- (b) For fixed appliances with a motor(s) larger than I/x ing units. Where the number of these appliances ex- horsepower, the total calculated load shall be based on ceeds three, use 75 percent of total. 125 percent of the largest motor plus the sum of the other (5) Derive amperes for freestanding range (as distin- loads.Where a branch circuit supplies continuous load(s)or guished from separate ovens and cooking units) by di- any combination of continuous and noncontinuous loads, viding the following values by 240 volts: the branch-circuit conductor size shall be in accordance with 210.19(A). Nameplate Rating (watts) Use (volt-amperes) (c) The rating of a single cord-and-plug-connected ap- 0-10,000 fiance supplied b other than an individual branch circuit 8(1 percent of rating P pP Y Over l0,{)00-12,St)U 8,000 shall not exceed 80 percent of the circuit rating. Over 12,500-13,500 8,400 (d) The rating of a range branch circuit shall be based Over 13,500-14,500 8,800 on the range demand as specified for ranges in Over 14,500-15,500 9,200 Over 15,500-16,500 9.600 552.47(B)(5). Over 16,500-17,500 10,000 552.47 Calculations. The following method shall be em- ployed in computing the supply-cord and distribution- (6) If outlets or circuits are provided for other than factory- panelboard load for each feeder assembly for each park installed appliances, include the anticipated load. trailer in lieu of the procedure shown in Article 220 and FPN: Refer W Annex D. Example D 12, for an illustration shall be based on a 3-wire, 208Y/120-volt or 1201240-volt of the application of this calculation. supply with 120-volt loads balanced between the two phases of the 3-wire system. (C) Optional Method of Calculation for Lighting and Appliance Load. For park trailers, the optional method for (A) Lighting and Small-Appliance Load. Lighting Volt- calculating lighting and appliance load shown in 220,82 Amperes: Length times width of park trailer floor (out- shaIl be permitted. side dimensions) times 33 volt-amperes/m" (3 VA/ft2y For example, 552.48 Wiring Methods. Length x width x 3 = lighting volt-amperes (A) Wiring Systems. Cables and raceways installed in ac- Small-Appliance Volt-Amperes: Number of circuits cordance with Articles 320, 322, 330 through 340, 342 times 1500 volt-amperes for each 20-ampere appliance re- through 362, 386, and 388 shall be permitted in accordance ceptacle circuit (see definition of Appliance, Portable with with their applicable article, except as otherwise specified fine print note) including 1500 volt-amperes for laundry in this article.An equipment grounding means shall be pro- circuit. For example, vided in accordance with 250.118. No. of circuits x 1500 = small-appliance volt-amperes Total: Lighting volt-amperes plus small-appliance volt- (B) Conduit and 7bbing. Where rigid metal conduit or amperes = total volt-amperes intermediate metal conduit is terminated at an enclosure First 3000 total volt-amperes at 100 percent plus re- with a locknut and bushing connection, two locknuts shall mainder at 35 percent = volt-amperes to be divided by 240 be provided, one inside and one outside of the enclosure. volts to obtain current (amperes) per leg. All cut ends of conduit and tubing shall be reamed or oth- erwise finished to remove rough edges. (B) Total Load for Determining Power Supply.Total load for determining power supply is the sum of the following: (C) Nonmetallic Boxes. Nonmetallic boxes shall be ac- (I) Lighting and small-appliance load as calculated in ceptahle only with nonmetallic-sheathed cable or nonmetal- 552.47(A). lic raceways. (2) Nameplate amperes for motors and heater loads (ex- (D) Boxes. In wails and ceilings constructed of wood or haust fans, air conditioners, electric, gas, or oil heat- other combustible material, boxes and fittings shall be flush ing). Ornit smaller of the heating and cooling loads, with the finished surface or project therefrom. 2tH)8 Edition NATIONAL ELECTRICAL C'ODF 70-493 552.48 ARTICLE 552—PARK TRAILERS (E) Mounting.Wall and ceiling boxes shall be mounted in (M) Moisture or Physical Damage. Where outdoor or accordance with Article 314, under-chassis wiring is 120 volts, nominal, or over and is Exception No. 1: Snap-in-type boxes or boxes provided exposed to moisture or physical damage, the wiring shall be with special wall or ceiling brackets that securely fasten Protected by rigid metal conduit, by intermediate metal bores in walls or ceilings shall be permitted. conduit, by electrical metallic tubing, by rigid nonmetallic conduit, or by Type MI cable that is closely routed against Exceptions Na. 2: A wooden plate providing a 3S �nm frames and equipment enclosures or other raceway or cable (11/z-in.) minimum width backing around the box and of identified for the application. a thickness of 13 nun (112 in.) or greater(actual)attached directly to the wall panel shall be considered as ap- (N) Component Interconnections. Fittings and connec- proved means for mounting outlet boxes. tors that are intended to be concealed at the time of assem- (F) Sheath Armor. The sheath of nonmetallic-sheathed bly shall be listed and identified for the interconnection of cable, metal-clad cable, and Type AC cable shall be con- building components. Such fittings and connectors shall be tinuous between outlet boxes and other enclosures. equal to the wiring method employed in insulation, tem- perature rise, and fault-current withstanding, and shall be (G) Protected. Metal-clad, Type AC, or nonmetallic- capable of enduring the vibration and shock occurring in sheathed cables and electrical nonmetallic tubing shall be park trailers. permitted to pass through the centers of the wide side of 2 by 4 wood studs. However, they shall be protected where (0) Method of Connecting Expandable Units. The they pass through 2 by 2 wood studs or at other wood studs method of connecting expandable units to the main body of or frames where the cable or tubing would be less than the vehicle shall comply with the following as applicable: 32 mm (11/4 in.) from the inside or outside surface. Steel (1) That portion of a branch circuit that is installed in an plates on each side of the cable or tubing, or a steel tube, expandable unit shall be permitted to he connected to with not less than 1.35 mm (0.053 in.) wall thickness, shall the branch circuit in the main body of the vehicle by be installed to protect the cable or tubing. These plates or means of a flexible cord or attachment plug and cord tubes shall be securely held in place. Where nonmetallic- listed for hard usage.The cord and its connections shall sheathed cables pass through punched, cut, or drilled slots conform to all provisions of Article 400 and shall be or holes in metal members, the cable shall be protected by considered as a permitted use under 400.7. bushings or grommets securely fastened in the opening (2) If the receptacle provided for connection of the cord to prior to installation of the cable. the main circuit is located on the outside of the unit, it shall be protected with a ground-fault circuit interrupter (H) Cable Supports.Where connected with cable connec- for personnel and be listed For wet locations. A cord tors or clamps, cables shall be supported within 300 mm located on the outside of a unit shall be identified for (12 in.)of outlet boxes,distribution pane lboards, and splice outdoor use. boxes on appliances. Supports shall be provided every 1.4 m (4'/2 ft) at other places. (3) Unless removable or stored within the unit interior, the cord assembly shall have permanent provisions for pro- (1) Nonmetallic Box Without Cable Clamps.Nonmetallic- tection against corrosion and mechanical damage while sheathed cables shall be supported within 200 mm(8 in.)of the unit is in transit. a nonmetallic outlet box without cable clamps. (4) If an attachment plug and cord is used, it shall be Exception: Where wiring devices with integral enclosures installed so as not to permit exposed live attachment are employed with a loop of extra cable to permit future plug pins. replacement of the device, the cable loop shall be consid- (P) Prewiring for Air-Conditioning Installation. Prewir- ered as an integral portion of the device. ing installed for the purpose of facilitating future air- (J) Physical Damage. Where subject to physical damage, conditioning installation shall comply with the applicable exposed nonmetallic cable shall be protected by covering portions of this article and the following: boards, guard strips, raceways, or other means. (1) An overcurrent protective device with a rating com- patible with the circuit conductors shall be installed (K) Metal Faceplates.Metal faceplates shall be of ferrous metal not less than 0.76 m in the distribution panelboard and wiring connec- m (0.030 in.) in thickness or of in t completed, nonferrous metal not less than 1.0 mm (0.040 in.) in thick- ness. Nonmetallic faceplates shall be listed. (2) The load end of the circuit shall terminate in a junction box with a blank cover or other listed enclosure.Where (L) Metal Faceplates Grounded. Where metal faceplates a junction box with a blank cover is used, the free ends are used, they shall be grounded. of the conductors shall be adequately capped or taped. 70-494 NATIONAL ELECTRICAL CODE 2009 Edition ARTICLE 552—PARK TRAILERS 552.56 (3) A label conforming to 552.44(D) shall be placed on or (C) Outdoor Outlets, Luminaires, Air-Cooling Equip- adjacent to the junction box and shall read as follows: ment,and So On.Outdoor luminaires and other equipment AIR-CONDITIONING CIRCUIT. shall be listed for outdoor use or wet Iocations. THIS CONNECTION IS FOR AIR CONDITIONERS 552.55 Grounding. (See also 552.57 on bonding of non— RATED 110-125-VOLT AC, 60 HZ, current-carrying metal parts.) AMPERES MAXIMUM. DO NOT EXCEED CIRCUIT RATING. (A) Power-Supply Grounding. The grounding conductor in the supply cord or feeder shall be connected to the An ampere rating, not to exceed SO percent of the grounding bus or other approved grounding means in the circuit rating, Shall be legibly marked in the blank space. distribution panelboard. (4) The circuit shall serve no other purpose. (B) Distribution Panelboard.The distribution panelboard 552.49 Maximum Number of Conductors in Boxes. The shall have a grounding bus with sufficient terminals for all maximum number of conductors permitted in boxes shall grounding conductors or other approved grounding means. be in accordance with 314.16. (C) Insulated Grounded Conductor. The grounded cir- 552.50 Grounded Conductors. The identification of cuit conductor shall be insulated from the equipment grounded conductors shall be in accordance with 200.6. grounding conductors and from equipment enclosures and other grounded parts. The grounded circuit conductor ter- 552.51 Connection of Terminals and Splices. Conductor minals in the distribution panelboard and in ranges, clothes splices and connections at terminals shall be in accordance dryers, counter-mounted cooking units, and wall-mounted with 110.14. ovens shall be insulated from the equipment enclosure, Bonding screws, straps, or buses in the distribution panel- 552,52 Switches. Switches shall be rated as required by board or in appliances shall be removed and discarded. 552.52(A) and (B). Connection of electric ranges and electric clothes dryers utilizing a grounded conductor, if cord-connected, shall be (A) Lighting Circuits. For lighting circuits, switches shall made with 4-conductor cord and 3-pole,4-wire, grounding- be rated not less than 10 amperes, 1201125 volts, and in no type plug caps and receptacles. case less than the connected load. 552.56 Interior Equipment Grounding. (B) Motors or Other Loads. For motors or other loads, (A) Exposed Metal Parts. In the electrical system, all ex- switches shall have ampere or horsepower ratings, or both, posed metal parts, enclosures, frames, lurninaire canopies, adequate for loads controlled. (An ac general-use snap switch shall be permitted to control a motor 2 hp or less and so forth, shall be effectively bonded to the grounding terminals or enclosure of the distribution panelboard. with full-load current not over SO percent of the switch ampere rating.) (B) Equipment Grounding Conductors. Bare conductors or conductors with insulation or individual covering(hat is 552.53 Receptacles. All receptacle outlets shall be of the green or green with one or more yellow stripes shall be grounding type and installed in accordance with 210.21 and used for equipment grounding conductors only. 406.3. (C) Grounding of Electrical Equipment. Where ground- 552.54 Luminaires. ing of electrical equipment is specified,it shall be permitted as follows: (A) General. Any combustible wall or ceiling finish ex- (1) Connection of metal raceway(conduit or electrical me- posed between the edge of a luminaire canopy or pan and tallic tubing), the sheath of Type MC and Type MI the outlet box shall be covered with noncombustible mate- cable where the sheath is identified for grounding, or rial or a material identified for the purpose. the armor of Type AC cable to metal enclosures. (B) Shower Luminaires. If a luminaire is provided over a (2) A connection between the one or more equipment bathtub or in a shower stall, it shall be of the enclosed and grounding conductors and a metal box by means of a gasketed type and listed for the type of installation, and it grounding screw, which shall be used for no other pur- shall be ground-fault circuit-interrupter protected, pose, or a listed grounding device. The switch for shower luminaires and exhaust fans, lo- (3) The equipment grounding conductor in nonmetallic- cated over a tub or in a shower stall, shall be Iocated out- sheathed cable shall be permitted to be secured under a side the tub or shower space. screw threaded into the luminaire canopy other than a 2008 Edition NATIONAL HLECTRICAL CODE 70__495 552,57 ARTICLE 552—PARK TRAILERS mounting screw or cover screw or attached to a listed (2) The lower panel of the metal exterior covering is se- grounding means (plate) in a nonmetallic outlet box for cured by metal fasteners at each cross member of the luminaire mounting (grounding means shall also be chassis, or the lower panel is connected to the chassis permitted for luminaire attachment screws), by a metal strap. (D) Grounding Connection in Nonmetallic Box. A con- (E) Gas, Water, and Waste Pipe Bonding. The gas, wa- nection between the one or more grounding conductors ter, and waste pipes shall be considered grounded if they brought into a nonmetallic outlet box shall be arranged so are bonded to the chassis. that a connection can be made to any fitting or device in that box that requires grounding. (F) Furnace and Metal Air Duct Bonding. Furnace and metal circulating air ducts shall be bonded. (E) Grounding Continuity. Where more than one equip- ment grounding conductor of a branch circuit enters a box, 552.58 Appliance Accessibility and Fastening. Every ap- all such conductors shall be in good electrical contact with pliance shall be accessible for inspection, service, repair, each other, and the arrangement shall be such that the dis- and replacement without removal of permanent construc- connection or removal of a receptacle, fixture, including a tion, Means shall be provided to securely fasten appliances luminaire, or other device fed from the box will not inter- in place when the park trailer is in transit. fere with or interrupt the grounding continuity. 552,59 Outdoor Outlets, Fixtures, Including Lumi- (F) Cord-Connected Appliances. Cord-connected appli- mires,Air-Cooling Equipment, and So On. ances, such as washing machines, clothes dryers, refrigera- (A) Listed for Outdoor Use. Outdoor fixtures, including tors, and the electrical system of gas ranges, and so on, luminaires, and equipment shall be listed for outdoor use. shall be grounded by means of an approved cord with Outdoor receptacle or convenience outlets shall be of a equipment grounding conductor and grounding-type attach- gasketed-cover type for use in wet locations. ment plug. (B) Outside Heating Equipment, Air-Conditioning 552.57 Bonding of Non-Current-Carrying Metal Parts. Equipment,or Both.A park trailer provided with a branch circuit designed to energize outside heating equipment or (A) Required Bonding. All exposed non-current-carrying air-conditioning equipment, or both, located outside the metal parts that may become energized shall be effectively park trailer, other than room air conditioners, shall have bonded to the grounding terminal or enclosure of the dis- such branch-circuit conductors terminate in a listed outlet tribution panelboard. box or disconnecting means located on the outside of the (B) Bonding Chassis. A bonding conductor shall be con- park trailer. A label shall be permanently affixed within nected between any distribution panelboard and an ac- 150 mm (6 in.) from the listed box or disconnecting means cessible terminal on the chassis. Aluminum or copper- and shall contain the following information: clad aluminum conductors shall not be used for bonding THIS CONNECTION IS FOR HEATING if such conductors or their terminals are exposed to cor- AND/OR AIR-CONDITIONING EQUIPMENT. rosive elements. THE BRANCH CIRCUIT IS RATED AT NOT MORE Exception: Any park trailer that employs a unitized metal THAN AMPERES, AT VOLTS, chassis frame construction to which the distribution panel- 60 HZ, CONDUCTOR AMPACITY. board is securely fastened with a boll(s) and nut(s) or by A DISCONNECTING MEANS SHALL BE welding or riveting shall be considered to be bonded. LOCATED WITHIN SIGHT OF THE EQUIPMENT. The correct voltage and ampere rating shall be given. (C) Bonding Conductor Requirements. Grounding ter- The tag shall not be less than 0.51 mm (0.020 in.) thick minals shall be of the solderless type and listed as pressure etched brass, stainless steel, anodized or alclad aluminum, terminal connectors recognized for the wire size used. The or equivalent. The tag shall not be less than 75 mm x bonding conductor shall be solid or stranded, insulated or 45 mm Q in. x 11/4 in.) minimum size. bare, and shall be 8 AWG copper minimum or equivalent. (D) Metallic Roof and Exterior Bonding.The metal roof V. Factory Tests and exterior covering shall be considered bonded where 552.60 Factory Tests (Electrical). Each park trailer shall both of the following conditions apply: be subjected to the tests required by 552.60(A) and (B). (1) The metal panels overlap one another and are securely attached to the wood or metal frame parts by metal (A) Circuits of 120 Volts or 1201240 Volts. Each park fasteners. trailer designed with a 120-volt or a 120/240-volt electrical 70-496 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 553—FLOATING BUILDINGS 553.8 system shall withstand the applied potential without electri- 553.6 Feeder Conductors. Each floating building shall be cal breakdown of a ]-minute, 900-volt dielectric strength supplied by a single set of feeder conductors from its ser- test, or a 1-second, 1080-volt dielectric strength test, with vice equipment. all switches closed, between ungrounded and grounded conductors and the park trailer ground. During the test, all F.xc•eptiora: Where the floating building Jags multiple orc•u- panc); each occupant shall be pennitted to be supplied by a switches and other controls shall be in the on position. the ncc single set of feeder conductors extended u- Fixtures, including luminaires, and permanently installed t rnaaa f appliances shall not be required to withstand this test, pant's sert,ice equipment to the occupant's panelboard, Each park trailer shall be subjected to the following: 553.7 Installation of Services and Feeders. (1) A continuity test to ensure that all metal parts are prop- erly bonded (A) Flexibility. Flexibility of the wiring system shall be (2) Operational tests to demonstrate that all equipment is maintained between floating buildings and the supply con- properly connected and in working order ductors. All wiring shall be installed so that motion of the (3) Polarity checks to determine that connections have Water surface and changes in the water level will not result been properly made in unsafe conditions. (4) Receptacles requiring GFCI protection shall be tested (B) Wiring Methods. Liquidtight Flexible metal conduit or for correct function by the use of a GFCI testing device liquidtight flexible nonmetallic conduit with approved fit- (B) Low-Voltage Circuits. An operational test of IOW- tings shall be permitted for feeders and where flexible con- nections are required for services. Extra-hard usage par- voltage circuits shall be conducted to demonstrate that all table power cable listed for both wet locations and sunlight equipment is connected and in electrical working order.This resistance shall be permitted for a feeder to a floating build- test shall be performed in the final stages of production after ing where flexibility is required. Other raceways suitable all outer coverings and cabinetry have been secured. for the location shall be permitted to be installed where flexibility is not required. FPN: See 555.1 and 555.13. ARTICLE 553 Floating Buildings III. Grounding 553.8 General Requirements. Grounding at floating L General buildings shall comply with 553.8(A) through (D). 553.1 Scope. This article covers wiring, services, feeders, (A) Grounding of Electrical and Nonelectrical farts. and grounding for floating buildings. Grounding of both electrical and nonelectrical parts in a 553.2 Definition. floating building shall be through connection to a ground- Floating Building. A building unit as defined in Article ing bus in the building panelboard, 100 that floats on water, is moored in a permanent location, (B) Installation and Connection of Equipment Ground- and has a premises wiring system served through connec- ing Conductor. The equipment grounding conductor shall tion by permanent wiring to an electrical supply system not be installed with the feeder conductors and connected to a located on the premises. grounding terminal in the service equipment. 553.3 Application of Other Articles. Wiring for floating (C) Identification of Equipment Grounding Conductor. buildings shall comply with the applicable provisions of other The equipment grounding conductor shall be an insulated articles of this Code, except as modified by this article. copper conductor with a continuous outer finish that is ei- ther green or green with one or more yellow stripes. For conductors larger than 6 AWG, or where multiconductor II. Services and Feeders cables are used, re-identification of conductors as allowed 553.4 Location of Service Equipment.The service equip- in 250.119(A)(2)(2) and (A)(2)(3) or 250.119(B)(2) and ment for a floating building shall be located adjacent to, but (13)(3) shall be permitted. not in or on, the building or any floating structure. (D) Grounding Electrode Conductor Connection. The 553.5 Service Conductors. One set of service conductors grounding terminal in the service equipment shall be shall be permitted to serve more than one set of service grounded by connection through an insulated grounding equipment. electrode conductor to a grounding electrode on shore. 2(H)8 Edition NATIONAL ELEMRICAL CODE 70-497 553.9 ARTICLE 555—MARINAS AND BOATYARDS 553.9 Insulated Neutral. The grounded circuit conductor (1) In Iand areas subject to tidal fluctuation, the electrical (neutral) shall be an insulated conductor identified in com- datum plane is a horizontal plane 606 mm (2 ft) above pliance with 200.6. The neutral conductor shall be con- the highest tide level for the area occurring under nor- nected to the equipment grounding terminal in the service mal circumstances, that is, highest high tide. equipment, and, except for that connection, it shall be in- (2) In land areas not subject to tidal fluctuation, the elec- sulated from the equipment grounding conductors, equip- trical datum plane is a horizontal plane 606 mm (2 ft) ment enclosures, and all other grounded parts. The neutral above the highest water level for the area occurring conductor terminals in the panelboard and in ranges, under normal circumstances. clothes dryers, counter-mounted cooking units, and the like (3) The electrical datum plane for floating piers and Iand- shall be insulated from the enclosures. ing stages that are (a) installed to permit rise and fall response to water level, without lateral movement, and 553.10 Equipment Grounding. (b) that are so equipped that they can rise to the datum (A) Electrical Systems. All enclosures and exposed metal plane established for (1) or (2), is a horizontal plane parts of electrical systems shall be connected to the ground- 762 mm (30 in.) above the water level at the floating ing bus. pier or landing stage and a minimum of 305 mm (12 in.) above the level of the deck. (B) Cord-Connected Appliances. Where required to be Marine Power Outlet. An enclosed assembly that can in- grounded, cord-connected appliances shall be grounded by clude receptacles, circuit breakers, fused switches, fuses, means of an equipment grounding conductor in the cord watt-hour meter(s), and monitoring means approved for and a grounding-type attachment plug. marine use. 553.11 Bonding of Non–Current-Carrying Metal Parts. 555.4 Distribution System. Yard and pier distribution sys- All metal parts in contact with the water, all metal piping, terns shall not exceed 600 volts phase to phase, and all non–current-carrying metal parts that may become energized shall be connected to the grounding bus in the panelboard. 555.5 Transformers. Transformers and enclosures shall be specifically approved for the intended location.The bottom of enclosures for transformers shall not be located below the electrical datum plane. ARTICLE 555 555.7 Location of Service Equipment.The service equip- Marinas and Boatyards ment for floating docks or marinas shall be located adjacent to, but not on or in, the floating structure. 555.1 Scope. This article covers the installation of wiring 555.9 Electrical Connections.Electrical connections shall and equipment in the areas comprising fixed or floating be located at least 305 mm (12 in.) above the deck of a piers, wharves, docks, and other areas in marinas, boat- floating pier. Conductor splices, within approved junction yards, boat basins, boathouses, yacht clubs, boat condo- boxes, utilizing sealed wire connector systems listed and miniums, docking facilities associated with residential con- identified for submersion shall be permitted where located dominiums, any multiple docking facility, or similar above the waterline but below the electrical datum field for occupancies, and facilities that are used, or intended for use, floating piers. for the purpose of repair, berthing, launching, storage,or fuel- All electrical connections shall be located at least ing of small craft and the moorage of floating buildings. 305 mm (12 in.) above the deck of a fixed pier but not Private, noncommercial docking facilities constructed below the electrical datum plane. or occupied for the use of the owner or residents of the associated single-family dwelling are not covered by this 555.10 Electrical Equipment Enclosures. article. FPN: See NFPA 303-2006, Fire Protection Standard for (A) Securing and Supporting. Electrical equipment en- Marinas and Boatyards, for additional information. closures installed on piers above deck level shall be se- curely and substantially supported by structural members, 555.2 Definitions. independent of any conduit connected to them. If enclo- sures are not attached to mounting surfaces by means of Electrical Datum Plane. The electrical datum plane is de- external ears or lugs, the internal screw heads shall be fined as follows: sealed to prevent seepage of water through mounting holes. 70-498 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 555—MARINAS AND BOATYARDS 555.13 (B) Location. Electrical equipment enclosures on piers having an outer jacket rated to be resistant to temperature shall be located so as not to interfere with mooring lines, extremes, oil, gasoline, ozone, abrasion, acids, and chemi- cals shall be permitted as follows: 555.11 Circuit Breakers, Switches, Panelboards, and (1) As permanent wiring on the underside of piers(floating Marine Power Outlets. Circuit breakers and switches in- or fixed) stalled in gasketed enclosures shall be arranged to permit required manual operation without exposing the interior of (-) Where flexibility is necessary as on piers composed of the enclosure. All such enclosures shall be arranged with a floating sections weep hole to discharge condensation. (3) Temporary Wiring. Temporary wiring, except as per- mitted by Article 590, shall not be used to supply power to 555.12 Load Calculations for Service and Feeder Con- boats. ductors. General lighting and other loads shall be calcu- lated in accordance with Part III of Article 220, and, in (B) Installation. addition, the demand factors set forth in Table 555.12 shall be permitted for each service and/or feeder circuit supply- (1) Overhead Wiring. Overhead wiring shall be installed to avoid possible contact with masts and other parts of ing receptacles that provide shore power for boats. These calculations shall be permitted to be modified as indicated boats being moved in the yard. in notes (1) and (2) to Table 555.12. Where demand factors Conductors and cables shall be routed to avoid wiring closer than 6.0 m (20 ft) from the outer edge or any portion of Table 555.12 are applied, the demand factor specified in of the yard that can be used for moving vessels or stepping 220.61(B) shall not be permitted. or unstepping masts. Table 555.12 Demand Factors (2) Outside Branch Circuits and Feeders. Outside branch circuits and feeders shall comply with Article 225 Sum of the Rating of the except that clearances for overhead wiring in portions of Number of Receptacles Receptacles the yard other than those described in 555.13(B)(1) shall (%) not be less than 5.49 m (18 ft) abovegrade. 1-4 100 5--5 90 (3) Wiring Over and Under Navigable Water. Wiring 9-14 SO over and under navigable water shall be subject to approval 15-30 70 by the authority having jurisdiction. 31-40 60 41-50 50 FPN: See NFPA 303-2006, Fire Protection Standard for 51-70 40 Marinas and Boarvardr, for warning sign requirements. 71-plus 30 (4) Portable Power Cables. Notes: 1. Where shore power accommodations provide two receptacles spe- (a) Where portable power cables are permitted by cifically for an individual brat slip and these receptacles have differ- 555.13(A)(2), the installation shall comply with the following: ent voltages (for example, one 30 ampere, 125 volt and one 50 am pere, 1251250 volt). only the receptacle with the larger kilowatt (1} Cables shall be properly supported. demand shall be required to be calculated. (2) Cables shall be located on the underside of the pier. 2. If the facility being installed includes individual kilowatt-hour sub- (3) Cables shall be securely fastened by nonmetallic clips meters fir each slip and is being calculated using the criteria listed in to structural members other than the deck planking. Table 555.12,the total demand amperes may be multiplied by 0.9 to achieve the final demand amperes. (4) Cables shall not be installed where subject to physical damage. FPN: These demand factors may be inadequate in areas of (5) Where cables pass through structural members, they extreme hot or cold temperatures with loaded circuits for shall be protected against chafing by a permanently heating, air-conditioning, or refrigerating equipment. installed oversized sleeve of nonmetallic material. 555.13 Wiring Methods and Installation. (b) Where portable power cables are used as permitted in 555.13(A)(2)(2),there shall be an approved junction box (A) Wiring Methods. of corrosion-resistant construction with permanently in- stalled terminal blocks on each pier section to which the (1) General.Wiring methods of Chapter 3 shall be permit- feeder and feeder extensions are to be connected. Metal fed where identified for use in wet locations. junction boxes and their covers, and metal screws and parts (2) Portable Power Cables. Extra-hard usage portable that are exposed externally to the boxes, shall be of power cables rated not less than 167°F (75°C), 600 volts, corrosion-resistant materials or protected by material resis- listed for both wet locations and sunlight resistance; and tant to corrosion. 2008 Edition NATIONAL ELECTRICAL CODL 70-499 555.15 ARTICLE 555—MARINAS ARID BOATYARDS (5) Protection.Rigid metal or nonmetallic conduit suitable (A) Type. The disconnecting means shall consist of a cir- for the location shall be installed to protect wiring above cuit breaker, switch, or both, and shall be properly identi- decks of piers and landing stages and below the enclosure fied as to which receptacle it controls. that it serves. The conduit shall be connected to the enclo- sure by full standard threads. The use of special fittings of (B) Location. The disconnecting means shall be readily nonmetallic material to provide a threaded connection into accessible, located not more than 762 mm (30 in.)from the enclosures on rigid nonmetallic conduit, employing joint receptacle it controls, and shall be located in the supply design as recommended by the conduit manufacturer, for circuit ahead of the receptacle. Circuit breakers or switches attachment of the fitting to the conduit shall be acceptable, located in marine power outlets complying with this section provided the equipment and method of attachment are ap- shall be permitted as the disconnecting means. proved and the assembly meets the requirements of instal- lation in damp or wet locations as applicable. 555.19 Receptacles.Receptacles shall be mounted not less than 305 mm(12 in.)above the deck surface of the pier and 555.15 Grounding. Wiring and equipment within the not below the electrical datum plane on a fixed pier. scope of this article shall be grounded as specified in Ar- ticle 250 and as required by 555.15(A) through (E). (A) Shore Power Receptacles. (A) Equipment to Be Grounded. The following items (1) Enclosures. Receptacles intended to supply shore shall be connected to an equipment grounding conductor power to boats shall be housed in marine power outlets run with the circuit conductors in the same raceway, cable, listed as marina power outlets or listed for set locations, or or trench: shall be installed in listed enclosures protected from the (1) Metal boxes, metal cabinets, and all other metal en- weather or in listed weatherproof enclosures. The integrity closures of the assembly shall not be affected when the receptacles (2) Metal frames of utilization equipment are in use with any type of booted or nonbooted attachment (3) Grounding terminals of grounding-type receptacles plug/cap inserted. (B) Type of Equipment Grounding Conductor. The (2) Strain Relief. Means shall be provided where neces- equipment grounding conductor shall be an insulated cop- sary to reduce the strain on the plug and receptacle caused per conductor with a continuous outer finish that is either by the weight and catenary angle of the shore power cord. green or green with one or more yellow stripes.The equip- (3) Branch Circuits. Each single receptacle that supplies ment grounding conductor of Type MI cable shall be per- shore power to boats shall be supplied from a marine power mitted to be identified at terminations. For conductors outlet or panelboard by an individual branch circuit of the larger than 6 AWG, or where multiconductor cables are voltage class and rating corresponding to the rating of the used, re-identification of conductors as allowed in receptacle. 250.119(A)(2)(b) and (A)(2)(c) or 250.119(B)(2) and (13)(3) shall be permitted. FPN: Supplying receptacles at voltages other than the volt- ages marked on the receptacle may cause overheating or (C) Size of Equipment Grounding Conductor.The insu- malfunctioning of connected equipment, for example, sup- iated copper equipment grounding conductor shall be sized plying single-phase, 1201240-volt, 3-wire loads from a in accordance with 250.122 but not smaller than 12 AWG. 208Y/120-volt, 3-wire source. (D) Branch-Circuit Equipment Grounding Conductor. (4) Ratings. Shore power for boats shall be provided by The insulated equipment grounding conductor for branch single receptacles rated not less than 30 amperes. circuits shall terminate at a grounding terminal in a remote FPN: For locking-and grounding-type receptacles for aux- panelboard or the grounding terminal in the main service iliary power to boats, see NFPA 303-2006, Fire Protection equipment. Standard for Marinas and Boatyards. (E) Feeder Equipment Grounding Conductors.Where a (a) Receptacles rated 30 amperes and 50 amperes shall feeder supplies a remote panelboard, an insulated equip- be of the locking and grounding type. ment grounding conductor shall extend from a grounding FPN: For various configurations and ratings of locking and terminal in the service equipment to a grounding terminal grounding-type receptacles and caps, see ANSUNEMA in the remote panelboard. 18WD 6-1989, National Electrical Manufacturers Associa- tion's Standard for Dimensions of Attachment Plugs and 555.17 Disconnecting Means for Shore Power Connec- Receptacles. tion(s). Disconnecting means shall be provided to isolate (b) Receptacles rated 60 amperes and 100 amperes each boat from its supply connection(s). shall be of the pin and sleeve type. 70-500 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 590—TEMPORARY INSTALLATIONS 590.2 FPN: For various conlgurations and ratings of pin and more from dock sections that support fuel dispensers)shall sleeve receptacles, see ANSUUL 1686, UL Standard for be permitted to be Class I, Division 2 where documented Safety Pin and Sleeve Configurations. airspace is provided between dock sections to pernrit,flam- (B) Other Than Shore Power. mable liquids or vapors to dissipate and not travel to these dock sections. Such documentation shall comply with (1) Ground-Fault Circuit-Interrupter (GFCI) Protec- 500.4(A). tion for Personnel. Fifteen- and 20-ampere, single-phase, Exception Nn. 2: Dock, pier, or wharf sections that do not 125-volt receptacles installed outdoors, in boathouses, in buildings used for storage, maintenance, or repair where por- support fuel dispensers and do not directly abut sections table electrical hand tools, electrical diagnostic equipment, or that support fuel dispensers shall be permitted to be unclasp portable ]fighting equipment are to be used shall be provided sifted where documented air space is provided and where flammable liquids or vapors cannot travel to these dock with GFCI protection for personnel. Receptacles in other ]o- sections. Such documentation shall comply with 500.4(A). cations shall be protected in accordance with 210.8(B). (2) Marking.Receptacles other than those supplying shore FPN: See 500.4(A) for documentation requirements. power to boats shall be permitted to be housed in marine (2) Open Construction. Where the construction of piers, power outlets with the receptacles that provide shore power wharfs, or docks is open, such as decks built on stringers to boats, provided they are marked to clearly indicate that supported by pilings, floats, pontoons, or similar construe- they are not to be used to supply power to boats. tion, the following shall apply: (a) The area 450 mm (1$ in) above the surface of the 555.21 Motor Fuel Dispensing Stations -- Hazardous dock, pier, or wharf and extending 6.0 m (20 ft) horizon- (Classified) Locations. tally in all directions from the outside edge of the dispenser (A) General. Electrical wiring and equipment located at or and down to the water level shall be Class 1, Division 2. serving motor fuel dispensing locations shall comply with (b) Enclosures such as tubs, voids, pits, vaults, boxes, Article 514 in addition to the requirements of this article, depressions, piping chases, or similar spaces where flam- All electrical wiring for power and lighting shall be in- mable liquids or vapors can accumulate within 6.0 m(20 ft) stalled on the side of the wharf, pier, or dock opposite from of the dispenser shall be a Class I, Division 1 location. the liquid piping system. 555.22 Repair Facilities — Hazardous (Classified) Lo- FPN: For additional information, see NFPA 303-2006. cations. Electrical wiring and equipment Iocated at facili- Fire Protection Standard for Marinas and Boatyards, and ties for the repair of marine craft containing flammable or NFPA 30A-2008,Motor Fuel Dispensing Facilities and Re- combustible liquids or gases shall comply with Article 511 pair Garages. in addition to the requirements of this article. (B) Classification of Class I,Division 1 and 2 Areas.The 555,23 Marine Hoists, Railways, Cranes, and Mono- following criteria shall be used for the purposes of applying rails. Motors and controls for marine hoists, railways, Table 514.3(B)(1) and Table 514.3(B)(2) to motor fuel dis- cranes, and monorails shall not be located below the elec- pensing equipment on floating or fixed piers,wharfs,or docks. trical datum plane. Where it is necessary to provide electric (1) Closed Construction. Where the construction of float- power to a mobile crane or hoist in the yard and a trailing ing docks, piers, or wharfs is closed so that there is no cable is utilized, it shall be a listed portable power cable space between the bottom of the bock, pier, or wharf and rated for the conditions of use and be provided with an the water, such as concrete enclosed expanded foam or outer jacket of distinctive color for safety, similar construction,and having integral service boxes with supply chases, the following shall apply: (a) The space above the surface of the floating dock, pier, or wharf shall be a Class 1, Division 2 location with ARTICLE 590 distances as identified in Table 514.3(B)(1), Dispenser and Temporary Installations Outdoor. (b) The space below the surface of the floating dock, 590,1 Scope. The provisions of this article apply to tem- pier, or wharf, having areas or enclosures such as tubs, porary electric power and lighting installations. voids, pits, vaults, boxes, depressions, fuel piping chases, or similar spaces where flammable liquid or vapor can ac- 590.2 All Wiring Installations. cumulate, shall be a CIass 1, Division 1 location. (A) Other Articles. Except as specifically modified in this Exception No. 1: Dock,pier, or wharf sections that do not article, all other requirements of this Code for permanent support fuel dispensers and abut but are 6.0 m (20 ft) or wiring shall apply to temporary wiring installations. 2(X)8 Edition NATIONAL ELECTRICAL CODE 70-501 590.3 ARTICLE 590—TEMPORARY INSTALLATIONS (B) Approval.Temporary wiring methods shall be accept- Exception: Branch circuits installed for the purposes speci- able only if approved based on the conditions of use and fied in 590.3(B) or 590.3(C) shall be permitted to be run as any special requirements of the temporary installation. single insulated conductors. Where the wiring is installed in accordance with 590.3(B), the voltage to ground shall not 590.3 Time Constraints. exceed 150 volts, the wiring shall not be subject to physical damage, and the conductors shall be supported on insulators (A) During the Period of Construction. Temporary elec- at intervals of not more than 3.0 m (10 ft), or for festoon tric power and lighting installations shall be permitted dur- lighting, the conductors shall be so arranged that excessive ing the period of construction, remodeling, maintenance, strain is not transmitted to the lampholders. repair, or demolition of buildings, structures, equipment, or (D) Receptacles. All receptacles shall be of the grounding similar activities. type. Unless installed in a continuous metal raceway that (B) 90 Days.Temporary electric power and lighting instal- qualifies as an equipment grounding conductor in accor- lations shall be permitted for a period not to exceed 90 days dance with 250.118 or a continuous metal-covered cable for holiday decorative lighting and similar purposes. that qualifies as an equipment grounding conductor in ac- cordance with 250.118, all branch circuits shall include a (C) Emergencies and Tests. Temporary electric power and separate equipment grounding conductor, and all recep- lighting installations shall be permitted during emergencies tacles shall be electrically connected to the equipment and for tests, experiments, and developmental work. grounding conductor($). Receptacles on construction sites shall not be installed on branch circuits that supply tempo- (D) Removal. Temporary wiring shall be removed imme- rary lighting. Receptacles shall not be connected to the diately upon completion of construction or purpose for same ungrounded conductor of multi wire.circuits that sup- which the wiring was installed. ply temporary lighting- 590.4 General. (E) Disconnecting Means.Suitable disconnecting switches or plug connectors shall be installed to permit the discon- (A) Services. Services shall be installed in conformance nection of all ungrounded conductors of each temporary with Parts I through VIII of Article 230, as applicable. circuit. Multiwire branch circuits shall be provided with a means to disconnect simultaneously all ungrounded conduc- (B) Feeders. Overcurrent protection shall be provided in tors at the power outlet or panelboard where the branch circuit accordance with 240.4, 240.5, 240.100, and 240.101. Feed- originated.Identified handle ties shall be permitted. ers shall originate in an approved distribution center. Con- (F) Lamp Protection. All lamps for general illumination ductors shall be permitted within cable assemblies or within Shall be protected from accidental contact or breakage by a multiconductor cords or cables of a type identified in Table suitable luminaire or lampholder with a guard. 400.4 for hard usage or extra-hard usage. For the purpose Brass shell, paper-lined sockets, or other metal-cased of this section, Type NM and Type NMC cables shall be sockets shall not be used unless the shell is grounded. permitted to be used in any dwelling, building, or structure without any height limitation or limitation by building con- (G) Splices. On construction sites, a box shall not be re- struction type and without concealment within wails,floors, quired for splices or junction connections where the circuit or ceilings. conductors are multiconductor cord or cable assemblies, provided that the equipment grounding continuity is main- Exception: Single insulated conductors shall be permitted tained with or without the box. See 110.14(B) and 400.9.A where installed for the purpose(s) specified in 590.3(C), box, conduit body, or terminal fitting having a separately where accessible only to qualified persons. bushed hole for each conductor shall be used wherever a change is made to a conduit or tubing system or a metal- (C) Branch Circuits. All branch circuits shall originate in sheathed cable system, an approved power outlet or panelboard. Conductors shall be permitted within cable assemblies or within multicon- (H) Protection from Accidental Damage. Flexible cords ductor cord or cable of a type identified in Table 400.4 for and cables shall be protected from accidental damage. hard usage or extra-hard usage. Conductors shall be pro- Sharp comers and projections shall be avoided. Where tected from overetuTent as provided in 240.4, 240.5, and passing through doorways or other pinch points, protection 240.100. For the purposes of this section, Type NM and shall be provided to avoid damage. Type NMC cables shall be permitted to be used in any (I) Termination(s) at Devices. Flexible cords and cables dwelling, building, or structure without any height limita- entering enclosures containing devices requiring termina- tion or limitation by building construction type and without tion shall be secured to the box with fittings designed for concealment within walls, floors, or ceilings. the purpose. 70-502 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 590—TEMPORARY INSTALLATIONS 590.7 (J) Support. Cable assemblies and flexible cords and shall be permitted for only those receptacle outlets used to cables shall be supported in place at intervals that ensure .supply equipment that would create a greater hazard if that they will be protected from physical damage, Support power were interrupted or having a design that is not com- shall be in the form of staples, cable ties, straps, or similar patible with GFCI protection. type fittings installed so as not to cause damage. Vegetation shall not be used for support of overhead spans of branch (B) Use of Other Outlets. Receptacles other than 125- circuits or feeders. volt, single-phase, 15-, 20-, and 30-ampere receptacles shall have protection in accordance with (B)(1) or the as- Exception: For holiday lighting in accordance with cured equipment grounding conductor program in accor- 590.3(B), where the conductors or cables are arranged dance with (B)(2). with proper strain relief devices, tension take-up devices, or other approved means to avoid damage from tec the movement GFCI Protection. Ground-fault circuit-interrupter pro- of the live vegetation, trees shall be permitted to be used for ection for personnel. support of overhead sprats of branch-circuit conductors or (2) Assured Equipment Grounding Conductor Program. cables. A written assured equipment grounding conductor program continuously enforced at the site by one or more designated 590.5 Listing of Decorative Lighting. Decorative lighting persons to ensure that equipment grounding conductors for used for holiday lighting and similar purposes, in accor- all cord sets,receptacles that are not a part of the permanent dance with 590.3(B), shall be listed. wiring of the building or structure, and equipment con- nected by cord and plug are installed and maintained in 590.6 Ground-Fault Protection for Personnel. Ground- accordance with the applicable requirements of 250.114, fault protection for personnel for all temporary wiring in- 250.138, 406.3(C), and 590,4(D). stallations shall be provided to comply with 590.6(A) and (B). This section shall apply only to temporary wiring in- (a) The following tests shall be performed on all cord stallations used to supply temporary power to equipment sets,receptacles that are not part of the permanent wiring of used by personnel during construction, remodeling, main- the building or structure, and cord-and-plug-connected tenance, repair, or demolition of buildings, structures, equipment required to be connected to an equipment equipment, or similar activities. This section shall apply to grounding conductor: power derived from an electric utility company or from an (1) All equipment grounding conductors shall be tested for on-site-generated power source, continuity and shall be electrically continuous. (2) Each receptacle and attachment plug shall be tested for (A) Receptacle Outlets. All 125-volt, single-phase, 15-, correct attachment of the equipment grounding conduc- 20-, and 30-ampere receptacle outlets that are not a part of tor. The equipment grounding conductor shall be con- the permanent wiring of the building or structure and that netted to its proper terminal. are in use by personnel shall have ground-fault circuit- (3) All required tests shall be performed as follows: interrupter protection for personnel, if a receptacle(s) is a. Before first use on site installed or exists as part of the permanent wiring of the b. When there is evidence of damage building or structure and is used for temporary electric power, ground-fault circuit-interrupter protection for per- c. Before equipment is returned to service follow- power, shall be provided. For the purposes of this section, A any repairs At cord sets or devices incorporating listed ground-fault d. At intervals not exceeding 3 months circuit-interrupter protection for personnel identified for (b) The tests required in item (2)(a) shall be recorded portable use shall be permitted, and made available to the authority having jurisdiction. Exception: In industrial establishments onh•, where condi- 590.7 Guarding. For wiring over 600 volts, nominal, suit- tions of maintenance and supervision ensure that only able fencing, barriers, or other effective means shall be qualified personnel are involved, an assured equipment provided to limit access only to authorized and qualified grounding conductor program as .specified in 590,6(B)(2) personnel. 2008 Edition NATIONAL ELECTRICAL CODF 70-503 CHAPTER 6 ARTICLE 600--ELECTRIC SIGNS AND OUTLINE LIGHTING Chapter 6 Special Equipment (B) Signs with LamphoIders for Incandescent Lamps. ARTICLE 600 Signs and outline lighting systems with lampholders for Electric Signs and Outline Lighting incandescent lamps shall be marked to indicate the maxi- mum allowable lamp wattage per lampholder. The mark- ings shall be permanently installed, in letters at least 6 mm I. General (t!4 in.) high, and shall be located where visible during 600.1 Scope.This article covers the installation of conduc- relamping. tors and equipment for electric signs and outline lighting. (C) Section Signs.Section signs shall be marked to indicate All installations and equipment using neon tubing, such as that field-wiring and installation instructions are required. signs, decorative elements, skeleton tubing, or art forms, are covered by this article. 600.5 Branch Circuits. 600.2 Definitions. (A) Required Branch Circuit. Each commercial building and each commercial occupancy accessible to pedestrians Electric-Discharge Lighting. Systems of illumination uti- shall be provided with at least one outlet in an accessible lizing fluorescent lamps, high-intensity discharge (HID) location at each entrance to each tenant space for sign or lamps, or neon tubing. outline lighting system use. The outlet(s) shall be supplied Neon Tubing. Electric-discharge tubing manufactured into by a branch circuit rated at least 20 amperes that supplies shapes that form letters, parts of letters, skeleton tubing, no other load. Service hallways or corridors shall not be outline lighting, other decorative elements, or art forms, considered accessible to pedestrians. and filled with various inert gases. ($) Rating. Branch circuits that supply signs shall be rated Section Sign. A sign or outline lighting system, shipped as in accordance with 600.5(B)(1) or (B)(2). subassemblies, that requires field-installed wiring between (1) Incandescent and Fluorescent. Branch circuits that the subassemblies to complete the overall sign.The suba%em- supply signs and outline lighting systems containing incan- blies are either physically joined to form a Single sign unit or descent and fluorescent forms of illumination shall be rated are installed as separate remote parts of an overall,sign. not to exceed 20 amperes. Sign Body.A portion of a sign that may provide protection (2) Neon. Branch circuits that supply neon tubing installa- from the weather but is not an electrical enclosure. tions shall not be rated in excess of 30 amperes. Skeleton Tubing.Neon tubing that is itself the sign or outline (C) Wiring Methods. Wiring methods used to supply lighting and not attached to an enclosure or sign body. signs shall comply with 600.5(C)(1), (C)(2), and (C)(3). 600.3 Listing. Electric signs, section signs, and outline (1) Supply. The wiring method used to supply signs and lighting — fixed, mobile, or portable—shall be listed and outline lighting systems shall terminate within a sign, an installed in conformance with that listing, unless otherwise outline lighting system enclosure, a suitable box, or a con- approved by special permission. duit body. (A) Field-Installed Skeleton Tubing. Field-installed skel- (2) Enclosures as Pull Boxes. Signs and transformer en- eton tubing shall not be required to be listed where installed closures shall be permitted to be used as pull or junction in conformance with this Code. boxes for conductors supplying other adjacent signs, out- line lighting systems, or floodlights that are part of a sign (B) Outline Lighting. Outline lighting shall not be re- and shall be permitted to contain both branch and second- quired to be listed as a system when it consists of listed ary circuit conductors. luminaires wired in accordance with Chapter 3. {3} Metal or Nonmetallic Poles. Metal or nonmetallic 600.4 Markings. poles used to support signs shall be permitted to enclose supply conductors, provided the poles and conductors are (A) Signs and Outline Lighting Systems. Signs and out- installed in accordance with 410.30(B). line lighting systems shall be marked with the manufactur- er's name, trademark, or other means of identification; and 600.6 Disconnects. Each sign and outline lighting system, input voltage and current rating. or feeder circuit or branch circuit supplying a sign or out- 70-504 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 600—ELECTRIC SIGNS AND OUTLINE LIGHTING b00.7 line lighting system, shall be controlled by an externally the equipment grounding conductor of the supply branch operable switch or circuit breaker that will open all un- circuit(s) or feeder using the types of equipment grounding grounded conductors. Signs and outline lighting systems conductors specified in 250.118. located within fountains shall have the disconnect located Exception: Portable cord-connected signs shall not be re- in accordance with 680.12. quired to be connected to the equipment grounding conduc- Exception No. 1: A disconnecting means shall not be re- for where protected by a system of double insulation or its quired for an exit directional sign located within a building. equivalent. Double insulated equipment shall be distinc- Exception No. 2: A disconnecting mea,zs shall not be re- tively marked. quired for cord-connected signs with an attachment plug. (2) Size of Equipment Grounding Conductor. The equipment grounding conductor size shall be in accordance (A) Location. with 250.122 rased on the rating of the overcurrent device (1) Within Sight of the Sign. The disconnecting means protecting the branch circuit or feeder conductors supplying shall be within sight of the sign or outline lighting system the sign or equipment. that it controls. Where the disconnecting means is out of (3) Connections.Equipment grounding conductor connec- the line of sight from any section that is able to be ener- tions shall be made in accordance with 250.130 and in a gized, the disconnecting means shall be capable of being method specified in 250.8. locked in the open position. The provision for locking or adding a lock to the disconnecting means must remain in (4) Auxiliary Grounding Electrode. Auxiliary grounding place at the switch or circuit breaker whether the lock is electrode(s)shall be permitted for electric Signs and outline installed or not. Portable means for adding a lock to the lighting systems covered by this article and shall meet the switch or circuit breaker shall not be permitted. requirements of 250.54. (2) Within Sight of the Controller. The following shall (5) Metal Building Parts. Metal parts of a building shall apply for signs or outline Iighting systems operated by elec- not be permitted as a secondary return conductor or an tronic or electromechanical controllers located external to equipment grounding conductor. the sign or outline lighting system: (1) The disconnecting means shall be permitted to be lo- (B) Bonding. cated within sight of the controller or in the same en- (1) Bonding of Metal Parts.Metal parts and equipment of closure with the controller. signs and outline lighting systems shall be bonded together (2) The disconnecting means shall disconnect the sign or and to the associated transformer or power-supply equip- outline lighting system and the controller from all un- ment grounding conductor of the branch circuit or feeder grounded supply conductors. supplying the sign or outline lighting system and shall meet (3) The disconnecting means shall be designed such that the requirements of 250.90. no pole can be operated independently and shall be capable of being locked in the open position. The pro- (2) Bonding Connections. Bonding connections shall be made in accordance with 250.8. visions for locking or adding a lock to the disconnect- ing means must remain in place at the switch or circuit (3) Metal Building Parts. Metal parts of a building shall breaker whether the lock is installed or not. Portable not be permitted to be used as a means for bonding metal means for adding a lock to the switch or circuit breaker parts and equipment of signs or outline lighting systems shall not be permitted. together or to the transformer or power-supply equipment (B) Control Switch Rating. Switches, flashers, and simi- grounding conductor of the supply circuit. lar devices controlling transformers and electronic power (4) Flexible Metal Conduit Length. Listed flexible metal supplies shall be rated for controlling inductive loads or conduit or listed liquidtight flexible metal conduit that en- have a current rating not less than twice the current rating closes the secondary circuit conductor from a transformer of the transformer, or power supply for use with neon tubing shall be permitted as a bonding means if the total accumulative length of the FPN: See 404.14 for rating of snap switches. conduit in the secondary circuit does not exceed 30 in 600.7 Grounding and Bonding. (100 ft). (5) Small Metal Parts. Small metal parts not exceeding (A) Grounding. 50 mm (2 in.) in any dimension, not likely to be energized, (1) Equipment Grounding. Signs and metal equipment of and spaced at least 19 mm (-114 in.) from neon tubing, shall outline Iighting systems shall be grounded by connection to not require bonding. 2008 Edition NATIONAL ELECTRICAL CODE 70-505 600.8 ARTICLE 600—ELECTRIC SIGNS AND OUTLINE LIGHTING (6) Nonmetallic Conduit. Where listed nonmetallic con- (C) Adjacent to Combustible Materials. Signs and out- duit is used to enclose the secondary circuit conductor from line lighting systems shall be installed so that adjacent a transformer or power supply and a bonding conductor is combustible materials are not subjected to temperatures in required, the bonding conductor shall be installed separate excess of 90°C (194°F). and remote from the nonmetallic conduit and be spaced at The spacing between wood or other combustible mate- least 38 mm (11/2 in.) from the conduit when the circuit is rials and an incandescent or HID lamp or lampholder shall operated at 100 Hz or less or 45 mm (13/4 in.) when the not be less than 50 mm (2 in.). circuit is operated at over 100 Hz. (D) Wet Location. Signs and outline lighting system (7) Bonding Conductors. Bonding conductors shall eom- equipment for wet location use, other than listed watertight ply with (a) and (b). type, shall be weatherproof and have drain holes, as neces- (a) Bonding conductors shall be copper and not sary, in accordance with the following: smaller than 14 AWG. (1) Drain holes shall not be larger than 13 mm (11 in.) or (b) Bonding conductors installed externally of a sign smaller than 6 mm ('/4 in.). or raceway shalt be protected from physical damage. (2) Every low point or isolated section of the equipment (8) Signs in Fountains. Signs or outline lighting installed shall have at least one drain hole. inside a fountain shall have all metal parts bonded to the (3) Drain holes shall be positioned such that there will be equipment grounding conductor of the branch circuit for no external obstructions. the fountain recirculating system. The bonding connection shall be as near as practicable to the fountain and shall be 600.10 Portable or Mobile Signs. permitted to be made to metal piping systems that are (A) Support. Portable or mobile signs shall be adequately bonded in accordance with 680.53. supported and readily movable without the use of tools. FPN: Refer to 600.32(1) for restrictions on length of high- voltage secondary conductors. (B) Attachment Plug. An attachment plug shall be pro- vided for each portable or mobile sign. 600.8 Enclosures. Live parts, other than lamps, and neon tubing shall be enclosed. Transformers and power supplies (C) Wet or Damp Location. Portable or mobile signs in provided with an integral enclosure, including a primary wet or damp locations shall comply with 600.10(C)(l) and and secondary circuit splice enclosure, shall not require an (C}(2}. additional enclosure. (1) Cords. All cords shall be junior hard-service or hard- (A) Strength. Enclosures shall have ample structural service types as designated in Table 400.4 and have an strength and rigidity. equipment grounding conductor. (B) Material. Sign and outline lighting system enclosures (2) Ground-Fault Circuit Interrupter.Portable or mobile signs shall be provided with factory-installed ground-fault shall be constructed of metal or shall be listed. circuit-interrupter protection for personnel. The ground- (C) Minimum Thickness of Enclosure Metal. Sheet cop- fault circuit interrupter shall be an integral part of the at- per or aluminum shall be at least 0.51 mm (0.020 in.) thick. tachment plug or shall be located in the power-supply cord Sheet steel shall be at least 0.41 mm (0.016 in.) thick. within 300 mm (12 in.) of the attachment plug. (D) Protection of Metal. Metal parts of equipment shall (D) Dry Location. Portable or mobile signs in dry loca- be protected from corrosion. tions shall meet the following: (1) Cords shall be SP-2, SPE-2, SPT-2, or heavier, as des- 600.9 Location. ignated in Table 400.4. (A) Vehicles. Sign or outline lighting system equipment (2) The cord shall not exceed 4.5 m (15 ft) in length. shall be at least 4.3 m (14 ft) above areas accessible to 600.12 Field-Installed Secondary Wiring. Field-installed vehicles unless protected from physical damage. secondary circuit wiring for electric signs and outline (B) Pedestrians. Neon tubing, other than dry-location por- lighting systems shall be in accordance with 600.12(A), table signs, readily accessible to pedestrians shall be pro- (B), or (C). tected from physical damage. (A) 1400 Volts or Less. Secondary circuit wiring of 1000 FPN: See 600.41(17) for additional requirements, volts or less shall comply With 600.31. 70-506 NATIONAL ELECTRICAL COVE 2008 Edition ARTICLE 600—ELECTRIC SIGNS AND OUTLINE LIGHTING 600.24 (B) Over 1E000 Volts. Secondary circuit wiring of over 600.22 Ballasts. 1000 volts shall comply with 6110.32. (A) Type. Ballasts shall be identified for the use and shall (C) Less Than 50 Volts. Secondary circuit wiring less be listed. than 50 volts shall be installed in accordance with either of the following: (B) Thermal Protection. Ballasts shall be thermally (l) Any wiring method included in Chapter 3 suitable for protected. the conditions. (2) Where the power Source complies with the require- 600.23 Transformelrs and Electronic Power Supplies. ments in 725.121,wiring methods shall be permaitted to (A) Type. Transformers and electronic power supplies be installed in accordance with 725.130(A) or(B). shall be identified for the use and shall be listed. 600.21 Ballasts, Transrormers, and Electronic Power (B) Secondary-Circuit Ground-Fault Protection. Trans- Supplies. formers and electronic power supplies other than the following (A) Accessibility. Ballasts, transformers, and electronic shall have secondary-circuit ground-fault protection: power supplies shall be located where accessible and shall (1) Transformers with isolated ungrounded secondaries be securely fastened in place. and with a maximum open circuit voltage of 7500 volts or less (B) Location. Ballasts, transformers, and electronic power (2) Transformers with integral porcelain or glass secondary supplies shall be installed as near to the lamps or neon housing for the neon tubing and requiring no field wir- tubing as practicable to keep the secondary conductors as ing of the secondary circuit short as possible. (C) Voltage. Secondary-circuit voltage shall not exceed (C) Wet Location. Ballasts, transformers, and electronic 15,000 volts, nominal, under any load condition. The power supplies used in wet locations shall be of the weather- voltage to ground of any output terminals of the second- proof type or be of the outdoor type and protected from the ary circuit shall not exceed 7500 volts, under any load weather by placement in a sign body or separate enclosure. condition. (D) Working Space. A working space at least 900 mm (D) Rating. Transformers and electronic power supplies (3 ft)high,900 mm(3 ft)wide, by 900 nun(3 ft) deep shall shall have a secondary-circuit current rating of not more be provided at each ballast, transformer, and electronic than 300 mA. power supply or at its enclosure where not installed in a sign. (E) Secondary Connections. Secondary circuit outputs shall not be connected in parallel or in series. (E) Attic and Soft Locations. Ballasts,transformers, and electronic power supplies shall be permitted to be located (F) Marking. A transformer or power supply shall be in attics and soffits, provided there is an access door at least marked to indicate that it has secondary-circuit ground- 900 mm by 562.5 mm (36 in. by 221/2 in.) and a passage- fault protection. way of at least 900 mm (3 ft) high by 600 mm (2 ft) wide with a suitable permanent walkway at least 300 mm(12 in.) 600.24 Class 2 Power Sources. Signs and outline lighting wide extending from the point of entry to each component. systems supplied by Class 2 transformers, power supplies, At least one lighting outlet containing a switch or con- and power sources shall comply with the applicable re- trolled by a wall switch shall be installed in such spaces.At quirements of Article 600 and 600.24(A), (B), and (C). least one point of control shall be at the usual,point of entry to these spaces.The lighting outlet shall be provided at or (A) Listing. Class 2 Power supplies and power sources near the equipment requiring servicing. shall be listed for use with electric signs and outline light- ing systems and shall comply with 725.121. (F) Suspended Ceilings. Ballasts, transformers, and elec- tronic power supplies shall be permitted to be located (B) Grounding. Metal parts of signs and outline lighting above suspended ceilings, provided their enclosures are se- systems shall be grounded and bonded is accordance with curely fastened in place and not dependent on the sus- C00.7. pended ceiling grid for support. Ballasts, transformers, and electronic power supplies installed in suspended ceilings (C) Secondary Wiring. Secondary wiring from Class 2 shall not be connected to the branch circuit by flexible cord. power Sources shall comply with 600.12(0). 2008 Edition NATIONAL ELECTRICAL COTE 70-$07 600.30 ARTICLE 6tH)—ELECTRIC SIGNS AND OUTLINE LIGHTING II. Field-Installed Skeleton Tubing and Wiring (5) Metal Building Parts. Metal parts of a building shall 600.30 Applicability. Part Q not be permitted as a secondary return conductor or an of this article shall apply to equipment grounding conductor. all of the following: (1) Field-installed skeleton tubing (B) Insulation and Size. Conductors shall be insulated, (2) Field-installed skeleton tubing wiring listed as gas tube sign and ignition cable type GTO, rated for 5, 10, or 15 kV, not smaller than 18 AWG, and have a These requirements are in addition to the requirements minimum temperature rating of 105°C (221 0F). of Part 1. (C) Installation. Conductors shall be so installed that they 600.31 Neon Secondary-Circuit Wiring, 1000 Volts or are not subject to physical damage. Less, Nominal. (D) Bends in Conductors. Sharp bends in insulated con- (A) Wiring Method. Conductors shall be installed using ductors shall be avoided. any wiring method included in Chapter 3 suitable for the conditions. (E) Spacing. Secondary conductors shall be separated from each other and from all objects other than insulators (B) Insulation and Size. Conductors shall be listed, insu- or neon tubing by a spacing of not less than 38 mm (I%2 in.). lated, and not smaller than 18 AWG. GTO cable installed in metal conduit or tubing requires no spacing between the cable insulation and the conduit (C) Number of Conductors in Raceway. The number of or tubing. conductors in a raceway shall be in accordance with Table 1 of Chapter 9. (F) Insulators and Bushings. Insulators and bushings for conductors shall be listed for use with neon secondary cir- (D) Installation. Conductors shall be installed so they are cuits over I000 volts. not subject to physical damage. (G) Conductors in Raceways. The insulation on all con- (E) Protection of Leads. Bushings shall be used to protect ductors shall extend not less than 65 mm (21/a in.) beyond wires passing through an opening in metal. the metal conduit or tubing. 600.32 Neon Secondary-Circuit Wiring, over 1000 (H) Between Neon Tlubing and Midpoint Return. Con- Volts, Nominal. ductors shall be permitted to run between the ends of neon tubing or to the secondary circuit midpoint return of listed (A) Wiring Methods. transformers or listed electronic power supplies and pro- (1) Installation. Conductors shall be installed in rigid vided with terminals or leads at the midpoint. metal conduit, intermediate metal conduit. PVC conduit, (1) Dwelling Occupancies.Equipment having an open cir- RTRC, liquidtight flexible nonmetallic conduit, flexible cuit voltage exceeding 1000 volts shall not be installed in metal conduit, liquidtight flexible metal conduit, electrical or on dwelling occupancies. metallic tubing, metal enclosures, on insulators in metal raceways, or other equipment listed for use with neon sec- (J) Length of Secondary Circuit Conductors. ondary circuits over 1000 volts. (1) Secondary Conductor to the First Electrode. The (2) Number of Conductors. Conduit or tubing shall con- length of secondary circuit conductors from a high- tain only one conductor. voltage terminal or lead of a transformer or electronic power supply to the first neon tube electrode shall not (3) Size. Conduit or tubing shall be a minimum of metric exceed the following: designator 16 (trade size 1/2). (1) 6 in (20 ft) where installed in metal conduit or tubing (4) Spacing from Grounded Parts. Other than at the lo- (2) 15 in (50 ft) where installed in nonmetallic conduit cation of connection to a metal enclosure or sign body, (2) Other Secondary Circuit Conductors. All other sec- nonmetallic conduit or flexible nonmetallic conduit shall be tions of secondary circuit conductor in a neon tube circuit spaced no less than 38 mm 0 t/2 in.) from grounded or shall be as short as practicable. bonded parts when the conduit contains a conductor op- erating at 100 Hz or less, and shall be spaced no less (K) Splices. Splices in high-voltage secondary circuit con- than 45 min (1'13 in.) from grounded or bonded parts ductors shall be made in listed enclosures rated over 1000 when the conduit contains a conductor operating at more volts. Splice enclosures Shall be accessible after installation than 100 Hz. and listed for the location where they are installed. 70-508 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 604—MANUFACTURED WIRING SYSTEMS 604.6 600.41 Neon Tubing. (2) Damp and Wet Locations. Electrode enclosures in- (A) Design. The length and desin of the tubing shall not stalled in damp and wet locations shall be specifically listed g cause a continuous overcurrent beyond the design loading and Identified for use in such locations. of the transformer or electronic power supply. FPN; See 110.3(B)covering installation and use of electri- cal equipment. (B) Support.Tubing shall be supported by listed tube sup- ports. The neon tubing shall be supported within 150 mm (6 in.) from the electrode connection. (C) Spacing.A spacing of not less than 6 mm (114 in.)shall ARTICLE 604 be maintained between the tubing and the nearest surface, Manufactured Wiring Systems other than its support. (D) Protection.Field-installed skeleton tubing shall not be 604.1 Scope. The provisions of this article apply to Field- subject to physical damage. Where the tubing is readily installed wiring using off-site manufactured subassemblies accessible to other than quali=fied persons, field-installed for branch circuits, remote-control circuits, signaling cir- skeleton tubing shall be provided with suitable guards or cuits, and communications circuits in accessible areas. protected by other approved means. 604.2 Definition. 600.42 Electrode Connections. Manufactured Wiring System. A system containing com- (A) Points of Transition. Where the bigb-voltage second- ponent parts that are assembled in the process of manufac- ary circuit conductors emerge from the wiring methods lure and cannot be inspected at the building site without specified in 600.32(A), they shall be enclosed in a listed damage or destruction to the assembly and used for the assembly. connection of luminaires,utilization equipment,continuous plug-in type busways, and other devices. (B) Accessibility. Terminals of the electrode shall not be accessible to unqualified persons. 604.3 Other Articles. Except as modified by the require- ments of this article, all other applicable articles of this (C) Electrode Connections. Connections shall be made Code shall apply. by use of a connection device, twisting of the wires to- gether, or use of an electrode receptacle. Connections shall 604.4 Uses Permitted. Manufactured wiring systems shall be electrically and mechanically secure and shall be in an be permitted in accessible and dry locations and in ducts, enclosure listed for the purpose. plenums, and other air-handling spaces where listed for this application and installed in accordance with 300.22. (D) Support. Neon secondary cooduetor(s) shall be sup- ported not more than ISO mm {6 in.} from the electrode Exception No. l: lit concealed spares, one end of tapped connection to the tubing. cable shall be permitted to extend into hollow walls for direct termination at switch and nutlet points. (E) Receptacles. Electrode receptacles shall be listed. Exception No. 2: Manufactured wiring= system assemblies (F) Bushings. Where electrodes penetrate an enclosure, installed outdoors shall he listed for use in outdoor locations. bushings listed for the purpose shall be used unless recep- tacles are provided. 604.5 Uses Not Permitted. Manufactured wiring system (G) Wet Locations. A listed cap shall be used to close the types shall not be permitted where limited by the applicable opening between neon tubing and a receptacle where the article in Chapter 3 for the wiring method used in its con- receptacle penetrates a building. Where a bushing or neon struction. tubing penetrates a building,the opening between neon tub- 604.6 Construction. ing and the bushing shall be sealed. (A) Cable or Conduit Types. (H) Electrode Enclosures. Electrode enclosures shall be listed. (1) Cables. Cable shall be one of the following; (1) Listed Type AC cable containing nominal 600-volt,8 to (1) Dry Locations. Electrode enclosures that are listed for 12 AWO insulated copper conductors with a bare or use in dry, damp, or wet locations shall be permitted to be insulated copper equipment grounding conductor installed and used in such locations. equivalent in size to the ungrounded conductor. 2008 Edition NATIONAL ELECTRICAL CODE 70-509 604.7 ARTICLE 605 OFFICE FURNISHINGS(CONSISTING OF LIGHTING ACCESSORIES AND WIRED PARTITIONS) (2) Listed Type MC cable containing nominal 600-volt, 8 tified for the purpose,and shall be part of a listed assembly for to 12 AWG insulated copper conductors with a bare or the appropriate system. All connector openings shall be de- insulated copper equipment grounding conductor signed to prevent inadvertent contact with live parts or capped equivalent in size to the ungrounded conductor. to effectively close the connector openings. (3) Listed Type MC cable containing nominal 600-volt, $ to 12 AWG insulated capper conductors with aground- (D) Other Component Parts. Other component parts ing conductor and armor assembly Iisted and identified shall be listed for the appropriate system. for grounding in accordance with 250.118(10). The combined metallic sheath and grounding conductor 604.7 Installation. Manufactured wiring systems shall be shall have a current-carrying capacity equivalent to that secured and supported in accordance with the applicable of the ungrounded copper conductor. cable or conduit article for the cable or conduit type Other cables as listed in 725.154, 800.113, 820.113, and employed. 830.179 shall be permitted in manufactured wiring systems for wiring of equipment within the scope of their respective articles. (2) Conduits.Conduit shall be listed flexible metal conduit ARTICLE 605 or listed liquidtight flexible conduit containing nominal Office Furnishings (Consisting 600-volt, 8 to 12 AWG insulated copper conductors with a of Lighting Accessories bare or insulated copper equipment grounding conductor and Wired Partitions) equivalent in size to the ungrounded conductor. Exception No. I to (1) and(2): A luminaire tap, no longer light- than 1.8 in (b ft) crud intended.for connection to cr .single 605.1 Scope. This article covers electrical equipment, light- lwrtinaire, shall be permitted to c•ntttaitr candrsrtnrs.smaller ing accessories, and wiring systems used to connect, or con- than I2 AWG but not smaller than 1 S AWG. tamed within, or installed on relocatable wired partitions. Exception No. 2 to (1) and(2): Listed manufactured wiring 605.2 General. Wiring systems shall be identified as suit- assemblies containing conductors smaller than 12 AWG able for providing power for lighting accessories and appli- shall be pernitted.for remote-control, signaling, or commrr ances in wired partitions. These partitions shall not extend nication circuits. from floor to ceiling. (3) Flexible Cord. Flexible cord suitable for hard usage, with minimum 12 AWG conductors, shall be permitted as Exception: Where permitted by the authority having juris- part of a listed factory-made assembly not exceeding 1.8 m diction, these relocatable wired partitions shall be permit- (6 ft) in length when making a transition between compo- ted to extend to, but shall not penetrate, the ceiling. nents of a manufactured wiring system and utilization equipment not permanently secured to the building struc- (A) Use.These assemblies shall be installed and used only ture. The cord shall be visible for its entire length and shall as provided for by this article, not be subject to strain or physical damage. (B) Other Articles. Except as modified by the requirements Exception: Listed electric-discharge luminaires that com- of this article, all other articles of this Code shall apply. ply with 410.62(C) shall be permitted with conductors smaller than 12 AWG. (C) Hazardous (Classified) Locations. Where used in (4) Busways. Busways shall be listed continuous plug-in hazardous (classified) locations, these assemblies shall type containing factory mounted,bare or insulated conduc- comply with Articles 500 through 517 in addition to this tors, which shall be copper or aluminum bars, rods, or article. tubes.The busway shall be grounded and provided with an equipment ground bulbar equivalent in size to the un- 605.3 Wireways. All conductors and connections shall be grounded busbar. The busway shall be rated nominal 600 contained within wiring channels of metal or other material volts, 20, 30, or 40 amperes. Busways shall be installed in identified as suitable for the conditions of use.Wiring chan- aecordance with 368.12, 368.17(D) and 368.30. eels shall be free of projections or other conditions that (B) Marking. Each section shall be marked to identify the may damage conductor insulation. type of cable, flexible cord, or conduit. 605.4 Partition Interconnections. The electrical connec- (C) Receptacles and Connectors.Receptacles and connec- tion between partitions shall be a flexible assembly identi- tors shall be of the locking type,uniquely polarized and iden- fied for use with wired partitions or shall be permitted to be 70--510 NATIONAL ELECTRICAL CODE. 2008 Edition ARTICLE 610—CRANES AND HOISTS 610.3 installed using flexible cord, provided all the following (A) Flexible Power-Supply Cord. The flexible power- conditions are met: supply cord shall be extra-hard usage type with 12 AWG or (1) The cord is extra-hard usage type with 12 AWG or larger conductors with an insulated equipment grounding larger conductors, with an insulated equipment ground- conductor and shall not exceed 600 mm (2 ft) in length. ing conductor. (2) The partitions are mechanically contiguous. (B) Receptacle Supplying Power. The receptacle(s) sup- plying power shall be on a separate circuit serving only (3) The cord is not longer than necessary for maximum panels and no other loads and shall be located not more than positioning of the partitions but is in no case to exceed 300 mm (12 in.) from the partition that is connected to it. 600 mm (2 ft). (4) The cord is terminated at an attachment plug-and-cord (C) Receptacle Outlets, Maximum. Individual partitions connector with strain relief. or groups of interconnected individual partitions shall not contain more than thirteen 15-ampere, 125-volt receptacle 605.5 Lighting Accessories. Lighting equipment listed outlets. and identified for use with wired partitions shall comply with 605.5(A), (B), and (C). (D) Multiwire Circuits, Not Permitted. Individual parti- tions or groups of interconnected individual partitions shall (A) Support, A means for secure attachment or support not contain multiwire circuits. shall be provided. FPN: See 210.4 for circuits supplying partitions in 605.6 (B) Connection. Where cord-and-plug connection is pro- and 605.7. vided, the cord length shall be suitable for the intended application but shall not exceed 2.7 m (9 ft) in length. The cord shall not be smaller than 18 AWG, shall contain an equipment grounding conductor, and shall be of the hard ARTICLE 610 usage type. Connection by other means shall be identified Cranes and Hoists as suitable for the condition of use. (C) Receptacle Outlet. Convenience receptacles shall not I. General be permitted in lighting accessories. 610.1 Scope. This article covers the installation of electri- 605.6 Fixed-Type Partitions. Wired partitions that are cal equipment and wiring used in connection with cranes, fixed (secured to building surfaces) shall be permanently monorail hoists, hoists, and all runways. connected to the building electrical system by one of the FPN: For further information, see ANSI B30,Sa env Code wiring methods of Chapter 3. Multiwire branch circuits sup- .f . plying power to the partition shall be provided with a means to for Cranes, Derricks, Heists, Jacks, and Slings. disconnect simultaneously all ungrounded conductors at the 610.3 Special Requirements for Particular Locations. panelboard where the branch circuit originates. (A) Hazardous(Classified)Locations.All equipment that 605.7 Freestanding-Type Partitions. Partitions of the operates in a hazardous (classified) location shall conform freestanding type (not fixed) shall be permitted to be con- to Article 500. nected to the building electrical system by one of the wiring methods of Chapter 3. Multiwire branch circuits supplying (1) Class I Locations. Equipment used in locations that power to permanently connected freestanding partitions are hazardous because of the presence of flammable gases shall be provided with a means to disconnect simulta- or vapors shall conform to Article 50). neously all ungrounded conductors at the panelboard where the branch circuit originates. (2) Class II Locations. Equipment used in locations that are hazardous because of combustible dust shall conform to 605.8 Freestanding-Type Partitions, Cord-and-Plug- Article 502. Connected. Individual partitions of the freestanding type, (3) Class III Locations. Equipment used in locations that or groups of individual partitions that are electrically con- are hazardous because of the presence of easily ignitible nected, are mechanically contiguous, and do not exceed fibers or flyings shall conform to Article 503. 9.0 m (30 ft) when assembled, shall be permitted to be connected to the building electrical system by a single flex- (B) Combustible Materials. Where a crane, hoist, or ible cord and plug, provided all of the conditions of monorail hoist operates over readily combustible material, 605.8(A) through (D) are met. the resistors shall be located as permitted in the following: 2008 Edition NATIONAL ELECTRICAL CODE 70-511 610.11 ARTICLE 510—CRANES AND HOISTS (1) A well ventilated cabinet composed of noncombustible (B) Bushing in Lieu of a Box. A bushing shall be permit- material constructed so that it does not emit flames or ted to be used in lieu of a box at the end of a rigid metal molten metal conduit, intermediate metal conduit, or electrical metallic (2) A cage or cab constructed of noncombustible material tubing where the raceway terminates at unenclosed controls that encloses the sides of the cage or cab from the floor or similar equipment, including contact conductors, collec- to a point at least 150 mm (6 in.) above the top of the tors, resistors, brakes, power-circuit limit switches, and do resistors split-frame motors. (C) Electrolytic Cell Lines. See 668.32. 610.13 Types of Conductors. Conductors shall comply with Table 310.13(A) unless otherwise permitted in 11. Wiring 610.13(A) through (D). 610.11 Wiring Method. Conductors shall be enclosed in (A) Exposed to External Heat or Connected to Resis- raceways or be Type AC cable with insulated grounding tors. A conductor(s) exposed to external heat or connected conductor, Type MC cable, or Type MI cable unless other- to resistors shall have a flame-resistant outer covering or be wise permitted or required in 610.11(A) through (E). covered with flame-resistant tape individually or as a group. (A) Contact Conductor. Contact conductors shall not be required to be enclosed in raceways, (B) Contact Conductors. Contact conductors along run- ways,crane bridges, and monorails shall be permitted to be (B) Exposed Conductors. Short lengths of exposed con- bare and shall be copper,aluminum, steel, or other alloys or ductors at resistors, collectors, and other equipment shall combinations thereof in the form of hard-drawn wire, tees. not be required to be enclosed in raceways. angles, tee rails, or other stiff shapes. (C) Flexible Connections to Motors and Similar Equip- (C) Flexibility. Where flexibility is required, flexible cord ment. Where flexible connections are necessary, flexible or cable shall be permitted to be used and, where necessary, stranded conductors shall be used. Conductors shall be in cable reels or take-up devices shall be used. flexible metal conduit, liquidtight flexible metal conduit, liquidtight flexible nonmetallic conduit, multiconductor (D) Class 1, Class 2, and Class 3 Circuits. Conductors cable, or an approved nonmetallic flexible raceway. for Class 1, Class 2, and Class 3 remote-control, signaling, (D) Pushbutton Station Multiconductor Cable. Where and power-limited circuits, installed in accordance with Ar- multiconductor cable is used with a suspended pushbutton tide 725, shall be permitted. station, the station shall be supported in some satisfactory manner that protects the electrical conductors against strain. 610.14 Rating and Size of Conductors. (E) Flexibility to Moving Parts. Where flexibility is re- (A) Ampacity. The allowable ampacities of conductors quired for power or control to moving parts, a cord suitable shall be as shown in Table 610.14(A). for the purpose shall be permitted, provided the following FPM: For the ampacities or conductors between controllers apply: and resistors, see 430.23. (1) Suitable strain relief and protection from physical dam- age is provided. (B) Secondary Resistor Conductors. Where the second- (2) In Class I, Division 2 locations, the cord is approved ary resistor is separate from the controller, the minimum for extra-hard usage. size of the conductors between controller and resistor shall be calculated by multiplying the motor secondary current 610.12 Raceway or Cable Terminal Fittings. Conductors by the appropriate factor from Table 610.14(B) and select- leaving raceways or cables shall comply with either ing a wire from Table 610.14(A). 610.12(A) or (B). (C) Minimum Size, Conductors external to motors and (A) Separately Bushed Hole. A box or terminal fitting controls shall be not smaller than 16 AWG unless otherwise that has a separately bushed hole for each conductor shall permitted in (1) or (2): be used wherever a change is made from a raceway or (1) 18 AWG wire in multiconductor cord shall be permit- cable to exposed wiring. A fitting used for this purpose ted for control circuits not exceeding 7 amperes. shall not contain taps or splices and shall not be used at (2) Wires not smaller than 20 AWG shall be permitted for luminaire outlets. electronic circuits. 70-512 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 610-CRANES AND HOISTS 610.14 Table 610.14(A) Ampacities of Insulated Copper Conductors Used with Short-Time Rated Crane and Hoist Motors. Based on Ambient Temperature of 30°C (86°F). Up to Three ace or Four dc' Simultaneously Energized Up to Four Simultaneously Energized Conductors Conductors in Raceway Maximum in Raceway or Cable' or Cable Maximum Operating Operating Temperature 75°C (167°F) 90°C (194°F) 125°C (257°F) Temperature Types TA,TBS, SA, SIS, Types MTW, RHW,THW, PFA,FEP, FEPB, RHH, Types FEP, FEPB, PFA,PFAH, THWN, XHHW, USE,ZW THHN, XHHW, Z, ZW SA, TFE, Z, ZW Size (AWG Size (AWG or kcmil) 60 Min 30 Min 60 Min 30 Min 60 Min 30 Min or kcmil) 16 10 12 - - - - 16 14 25 26 31 32 38 40 14 12 30 33 36 40 45 50 12 10 40 43 49 52 60 65 10 8 55 60 63 69 73 80 8 6 76 86 83 94 101 119 6 5 85 95 95 106 115 134 5 4 100 Ill 111 130 133 157 4 3 120 141 131 153 153 183 3 2 137 160 148 173 178 214 2 1 143 175 158 192 210 253 1 110 190 233 211 259 253 304 1/0 2/0 222 267 245 294 303 369 2/0 3/0 280 341 305 372 370 452 3/0 4/0 300 369 319 399 451 555 4/0 250 364 420 400 461 510 635 250 300 455 582 497 636 587 737 300 350 486 646 542 716 663 837 350 400 538 688 593 760 742 941 400 450 600 765 660 836 818 1042 450 500 660 847 726 914 896 1143 500 AMPACITY CORRECTION FACTORS Ambient Ambient Temperature For ambient temperatures other than 30'C (86°F), multiply the ampacities shown above Temperature (°C) by the appropriate factor shown below. (OF) 21-25 1.05 1.05 1.04 1.04 1.02 1.02 70-77 26-30 1.00 1.00 1.00 1.00 1.00 1.00 79-86 31-35 0.94 0.94 096 0.96 0.97 0.97 88-95 36-40 0.88 0.88 091 0.91 0.95 0.95 97-104 41-45 0.82 0.82 0.87 0.87 0.92 0.92 106-113 46-50 0.75 0.75 0.82 0.82 0.89 0.89 115--122 51-55 0.67 0.67 0.76 0.76 0.86 0.86 124-131 56-60 0.58 0.58 0.71 0.71 0.83 0.83 133-140 61-70 0.33 0.33 0.58 0.58 0.76 0.76 142-158 71-80 - - 0.41 0.41 0.69 0.69 160--176 81-90 - - - - 0.61 0.61 177-194 91-100 - - - - 0.51 0.51 195-212 101-120 - - -- - 0.40 0.40 213-248 Note: Other insulations shown in Table 310.13(A) and approved for the temperature and location shall be permitted to be substituted for those shown in Table 610.i4(A). The allowable ampacities of conductors used with 15-minute motors shall be the 30-minute ratings increased by 12 percent. 1 For 5 to 8 simultaneously energized power conductors in raceway or cable,the ampacity of each power conductor shall be reduced to a value of 80 percent of that shown in this table. 2 For 4 to 6 simultaneously energized 125°C (257°F) ae power conductors in raceway or cable, the ampacity of each power conductor shall be reduced to a value of 80 percent of that shown in this table. 2008 Edition NATIONAL ELECTRICAL CODE 70-513 610.15 ARTICLE 610—CRANES AND HOISTS Table 610.14(B) Secondary Conductor Rating Factors Table 610.14(E) Demand Factors Time in Seconds Ampacity of Wire in Number of Demand Percent of Full-Load Cranes or Hoists Factor On Off Secondary Current 2 0.95 5 75 35 3 Q.91 10 70 45 4 0.S7 15 75 55 5 0.84 15 45 65 6 0.81 15 30 75 7 0.78 15 15 85 Continuous Duty 110 610.15 Common Return. Where a crane or hoist is oper- ated by more than one motor, a common-return conductor (D) Contact Conductors. Contact wires shall have an am- of proper ampacity shall be permitted. pacity not less than that required by Table 610.14(A) for 75°C (167°F) wire, and in no case shall they be smaller than as shown in Table 610.14(D). III. Contact Conductors Table 610.14(D) Minimum Contact Conductor Size Based on 610.21 Installation of Contact Conductors. Contact con- Distance Between Supports ductors shall comply with 610.21(A) through (H). Maximum Distance Between End (A) Locating or Guarding Contact Conductors.Runway Minimum Size of Strain.Insulators or Clamp-Type contact conductors shall be guarded, and bridge contact Wire (AWG) Intermediate Supports conductors shall be Iocated or guarded in such a manner that persons cannot inadvertently touch energized current- 6 9.0 m(30 ft)or less carrying parts. 4 18 m (60 ft)or less Over 18 m(60 ft) (B) Contact Wires. Wires that are used as contact conduc- tors shall be secured at the ends by means of approved (E) Calculation of Motor Load. strain insulators and shall be mounted on approved insula- tors so that the extreme limit of displacement of the wire (1) Single Motor. For one motor, 100 percent of motor does not bring the latter within less than 38 mm (11/2 in.) nameplate full-load ampere rating shall be used. from the surface wired aver. (2) Multiple Motors on Single Crane or Hoist. For mul- tiple motors on a single crane or hoist, the minimum am- carried Supports Along Runways. Main contact conductors m carried along runways shall be supported on insulating sup- pacity of the power supply conductors shall be the name- ports placed at intervals not exceeding 6.0 m (20 ft) unless plate full-load ampere rating of the largest motor or group of motors for any single crane motion, plus 50 percent of otherwise permitted in fi10.21(F). the nameplate full-load ampere rating of the next largest Such conductors shall be separated at not less than 150 mm(6 in.),other than for monorail hoists where a spacing motor or group of motors, using that column of Table of not less than 75 mm (3 in.) shall be permitted. Where 610.14(A) that applies to the longest time-rated motor. necessary, intervals between insulating supports shall be per- (3) Multiple Cranes or Hoists on a Common Conductor mitted to be increased up to 12 m (40 ft), the separation be- System. For multiple cranes, hoists, or both, supplied by a tween conductors being increased proportionately. common conductor system, calculate the motor minimum ampacity for each crane as defined in 610.14(E), add them (I)) Supports on Bridges. Bridge wire contact conductors together, and multiply the sum by the appropriate demand shall be kept at least 65 mm (21/2 in.) apart, and, where the factor from Table 610.14(E). span exceeds 25 m (80 ft), insulating saddles shall be placed at intervals not exceeding 15 in (50 ft). (F) Other Loads. Additional loads, such as heating, light- ing, and air conditioning, shall be provided for by applica- (E) Supports for Rigid Conductors. Conductors along tian of the appropriate sections of this Code. runways and crane bridges, that are of the rigid type speci- fied in 610.13(B) and not contained within an approved (G) Nameplate. Each crane, monorail, or hoist shall be pro- enclosed assembly, shall be carried on insulating supports vided with a visible nameplate marked with the manufactur spaced at intervals of not more than 80 times the vertical er's name, rating in volts, frequency, number of phases, and dimension of the conductor, but in no case greater than circuit amperes as calculated in 610.14(E) and (F). 4.5 in (15 ft), and spaced apart sufficiently to give a clear 70-514 NATIONAL ELECTRICAL CODE 2(X)8 Edition ARTICLE 610—CRANES AND HOISTS 610.42 electrical separation of conductors or adjacent collectors 610.32 Disconnecting Means for Cranes and Monorail of not less than 25 mm (1 in.). Hoists. A motor-circuit switch, molded-case switch, or cir- cuit breaker shall be provided in the leads from the runway (F) Track as Circuit Conductor. Monorail, tram rail, or contact conductors or other power supply on all cranes and crane runway tracks shall be permitted as a conductor of monorail hoists. The disconnecting means shall be capable current for one phase of a 3-phase, ac system furnishing of being locked in the open position, The provision for power to the carrier, crane, or trolley, provided all of the lacking or adding a lock to the disconnecting means shall following conditions are met: be installed on or at the switch or circuit breaker used as the (1) The conductors supplying the other two phases of the disconnecting means and shall remain in place with or power supply are insulated. without the lock installed.Portable means for adding a lock (2) The power for all phases is obtained from an insulating to the switch or circuit breaker shall not be permitted. transformer. Where a monorail hoist or hand-propelled crane bridge (3) The voltage does not exceed 300 volts, installation meets all of the following, the disconnecting (4) The rail serving as a conductor shall be bonded to the means shall be permitted to be omitted: equipment grounding conductor at the transformer and (1) The unit is controlled from the ground or floor level. also shall be permitted to be grounded by the fittings (2) The unit is within view of the power supply discon- used for the suspension or attachment of the rail to a necting means. building or structure. (3) No fixed work platform has been provided for servicing (G) Electrical Continuity of Contact Conductors. All the unit. sections of contact conductors shall be mechanically joined Where the disconnecting means is not readily acces- to provide a continuous electrical connection. sible from the crane or monorail hoist operating station, means shall be provided at the operating station to open the (H) Not to Supply Other Equipment. Contact conductors power circuit to all motors of the crane or monorail hoist. shall not be used as feeders for any equipment other than the crane(s) or hoist(s) that they are primarily designed to serve. 610.33 Rating of Disconnecting Means. The continuous ampere rating of the switch or circuit breaker required by 610.22 Collectors. Collectors shall be designed so as to 610.32 shall not be less than 50 percent of the combined reduce to a minimum sparking between them and the con- short-time ampere rating of the motors or less than 75 per- tact conductor; and, where operated in rooms used for the cent of the sum of the short-time ampere rating of the storage of easily ignitible combustible fibers and materials, motors required for any single motion. they shall comply with 503.155. V. Overcurrent Protection IV. Disconnecting Means 610.41 Feeders, Runway Conductors. 610.31 Runway Conductor Disconnecting Means. A dis- connecting means that has a continuous ampere rating not (A) Single Feeder. The runway supply conductors and less than that calculated in 610.14(E) and (F) shall be pro- main contact conductors of a crane or monorail shall be video between the runway contact conductors and the Protected by an overcurrent device(s) that shall not be power supply. Such disconnecting means shall consist of a greater than the largest rating or setting of any branch- motor-circuit switch, circuit breaker, or molded-case circuit protective device plus the sum of the nameplate switch. This disconnecting means shall be as follows: ratings of all the other loads with application of the demand factors from Table 610.14(E). (1) Readily accessible and operable from the ground or floor level. (B) More Than One Feeder Circuit. Where more than (2) Capable of being locked in the open position. The pro- one feeder circuit is installed to supply runway conductors, vision for locking or adding a lock to the disconnecting each feeder circuit shall be sized and protected in compli- means shall be installed on or at the switch or circuit ance with 610.41(A). breaker used as the disconnecting means and shall re- main in place with or without the lock installed. Por- 610.42 Branch-Circuit Short-Circuit and Ground-Fault table means for adding a lock to the switch or circuit Protection. Branch circuits shall be protected in accor- breaker shall not be permitted as the means required to dance with 610.42(A). Branch-circuit taps, where made, be installed at and remain with the equipment. shall comply with 610.42(B). (3) Open all ungrounded conductors simultaneously. (A) Fuse or Circuit Breaker Rating. Crane, hoist, and (4) Placed within view of the runway contact conductors. monorail hoist motor branch circuits shall be protected by 2008 Edition NATIONAL ELECTRICAL,CODE 70-515 610.43 ARTICLE 610—CRANES AND HOISTS fuses or inverse-time circuit breakers that have a rating in overhead traveling crane shall not require individual motor accordance with Table 430.52. Where two or more motors overload protection, provided the largest motor does not operate a single motion, the sum of their nameplate current exceed 7'h hp and all motors are under manual control of ratings shall be considered as that of a single motor. the operator. (B) Taps. VI. Control (1) Multiple Motors. Where two or more motors are con- nected to the same branch circuit, each tap conductor to an 610.51 Separate Controllers. Each motor shall be pro- individual motor shall have an ampacity not less than one- vided with an individual controller unless otherwise permit- third that of the branch circuit. Each motor shall be pro- ted in 610.51(A) or (B). tected from overload according to 610.43. (A) Motions with More Than One Motor. Where two or (2) Control Circuits. Where taps to control circuits origi- more motors drive a single hoist, carriage, truck, or bridge, nate on the load side of a branch-circuit protective device, they shall be permitted to be controlled by a single controller. each tap and piece of equipment shall be protected in ac- (B) Multiple Motion Controller. One controller shall be cordance with 430.72. permitted to be switched between motors, under the follow- (3) Brake Coils.Taps without separate overcurrent protec- ing conditions: tion shall be permitted to brake coils. (1) The controller has a horsepower rating that is not lower than the horsepower rating of the largest motor. 610.43 Overload Protection. (2) Only one motor is operated at one time. (A) Motor and Branch-Circuit Overload Protection. 610.53 Overcurrent Protection. Conductors of control Each motor, motor controller, and branch-circuit conductor circuits shall be protected against overcurrent. Control cir- shall be protected from overload by one of the following cuits shall be considered as protected by overcurrent de- means: vices that are rated or set at not more than 300 percent of (1) A single motor shall be considered as protected where the ampacity of the control conductors, unless otherwise the branch-circuit overcurrent device meets the rating permitted in 610.53(A) or (B). requirements of 610.42. (2) Overload relay elements in each ungrounded circuit (A) Taps to Control `Iransformers. Taps to control trans- formers shall be considered as protected where the second- conductor, with all relay elements protected from short ary circuit is protected by a device rated or set at not more circuit by the branch-circuit protection. than 200 percent of the rated secondary current of the trans- (3) Thermal sensing devices, sensitive to motor tempera- former and not more than 200 percent of the ampacity of lure or to temperature and current, that are thermally in the control circuit conductors, contact with the motor winding(s). A hoist or trolley shall be considered to be protected if the sensing device (B) Continuity of Power. Where the opening of the con- is connected in the hoist's upper limit switch circuit so trol circuit would create a hazard, as for example, the con- as to prevent further hoisting during an overload con- trol circuit of a hot metal crane, the control circuit conduc- dition of either motor. tors shall be considered as being properly protected by the branch-circuit overcurrent devices. (B) Manually Controlled Motor. If the motor is manually controlled, with spring return controls, the overload protec- 610.55 Limit Switch. A limit switch or other device shall tive device shall not be required to protect the motor be provided to prevent the load block from passing the safe against stalled rotor conditions. upper limit of travel of all hoisting mechanisms. (C) Multimotor.Where two or more motors drive a single 610.57 Clearance.The dimension of the working space in trolley, truck, or bridge and are controlled as a unit and the direction of access to live parts that are likely to require protected by a single set of overload devices with a rating examination, adjustment, servicing, or maintenance while equal to the sum of their rated full-load currents, a hoist or energized shall be a minimum of 750 mm (2'/2 ft). Where trolley shall be considered to be protected if the sensing controls are enclosed in cabinets, the door(s) shall either device is connected in the hoist's upper limit switch circuit open at least 90 degrees or be removable. so as to prevent further hoisting during an overtemperature condition of either motor. VIL Grounding (D) Hoists and Monorail Hoists. Hoists and monorail 610.61 Grounding.All exposed non—current-carrying metal hoists and their trolleys that are not used as part of an parts of cranes, monorail hoists, hoists, and accessories, 70-516 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 620—ELEVATORS, DUMBWAITERS,ESCALATORS,MOVING WALKS,PLATFORM &STAIRWAY CHAIRLIFCS 620.3 including pendant controls, shall be bonded either by Controller,Motion.The electrical device(s)for that part of mechanical connections or bonding jumpers, where ap- the control system that governs the acceleration, speed, re- pEcable,so that the entire crane or hoist is a ground-fault tardation, and stopping of the moving member. current path as required or permitted by Article 250, Controller, Motor. The operative units of the control sys- Parts V and VII. tem comprised of the starter device(s) and power conver- Moving parts, other than removable accessories, or at- tachments that have metal-to-metal bearing surfaces, shall sion equipment used to drive an electric motor, or the pumping unit used to power hydraulic control equipment. be considered to be electrically bonded to each other through bearing surfaces for grounding purposes. The trol- Controller, Operation. The electrical device(s) for that ley frame and bridge frame shall not be considered as elec- part of the control system that initiates the starting, stop- trically grounded through the bridge and trolley wheels and ping, and direction of motion in response to a signal from its respective tracks.A separate bonding conductor shall be an operating device. provided. Machine Room(for Elevator,Dumbwaiter).An enclosed machinery space outside the hoistway, intended for full bodily entry, that contains the electrical driving machine or ARTICLE 620 the hydraulic machine. The room could also contain elec- trical and/or mechanical equipment used directly in connec- Elevators, Dumbwaiters, Escalators, tion with the elevator or dumbwaiter. Moving Walks, PIatform Lifts, and Stairw2t� Chaiurlifts Machinery Space (for Elevator, Dumbwaiter). A space inside or outside the hoistway, intended to be accessed with or without full bodily entry, that contains elevator or dumb- I. General waiter mechanical equipment, and could also contain elec- 620.1 Scope. This article covers the installation of electri- trical equipment used directly in connection with the eleva- cal equipment and wiring used in connection with eleva- for or dumbwaiter. This space could also contain the tors, dumbwaiters, escalators, moving walks, platform lifts, electrical driving machine or the hydraulic machine, and stairway chairlitts. Operating Device. The car switch, pushbuttons, key or FPN No. 1: For further information, see ASME A17.1- toggle switch(s), or other devices used to activate the op- 2004,Safety Code for Elevators and Escalators. eration controller. FPN No. 2: For further information, see CSA 844.1- Remote Machine Room and Control Room (for Eleva- 04/ASME-A17.5-2004, Elevator and Escalator Electrical tor,Dumbwaiter).A machine room or control room that is Equipment Certification Standard. not attached to the outside perimeter or surface of the walls, FPN No. 3: The teen wheelchair lift has been changed to ceiling, or floor of the hoistway, platform 1i. For further information, see ASME A18.1– 2003,Safety Standard,for Platform Lifts and Stairway Lifts. Remote Machinery Space and Control Space(for Eleva- 620.2 Definitions. tor,Dumbwaiter).A machinery space or control space that is not within the hoistway, machine room, or control room Control Room (for Elevator, Dumbwaiter). An enclosed and that is not attached to the outside perimeter or surface control space outside the hoistway, intended for full bodily of the walls, ceiling, or floor of the hoistway. entry, that contains the elevator motor controller. The room could also contain electrical and/or mechanical equipment Signal Equipment. Includes audible and visual equipment used directly in connection with the elevator or dumbwaiter such as chimes, gongs, lights, and displays that convey but not the electric driving machine or the hydraulic machine. information to the user. Control Space (for Elevator, Dumbwaiter). A space in- FPN No. I: The motor controller, motion controller, and side or outside the hoistway, intended to be accessed with operation controller may be located in a single enclosure or or without full bodily entry,that contains the elevator motor a combination of enclosures. controller. This space could also contain electrical and/or FPN No. 2: FPN Figure 620.2 is for information only. mechanical equipment used directly in connection with the elevator or dumbwaiter but not the electrical driving ma- 62Q.3 Voltage Limitations. The supply voltage shall not chine or the hydraulic machine. exceed 300 volts between conductors unless otherwise per- mitted in 620.3(A) through (C). Control System. The overall system governing the start- ing, stopping, direction of motion, acceleration, speed, and (A) Power Circuits. Branch circuits to door operator con- retardation of the moving member. trollers and door motors and branch circuits and feeders to 2008 Edition NATIONAL ELECTRICAL CODE 70-517 620.4 ARTICLE 620—ELEVATORS, DUMBWAITERS,ESCALATORS,MOVING WALKS,PLATFORM &STAIRWAY CHAIRLIFFS iMotion control Position and ' speed-sensing l devices r _ –_ Operation control i I I Motor controller Car operation Position I Power converter I ;<—� 1 control I � Dictation I 1 , _ Dictation ac molar I – ––[ Car assignment ' I control I I Moving 1 Open Operating Dictation Pattern Emergency enc Door Operating device I 9 Y I member l Aunlsto control generator �Machine do motor operator I Close i Interlace p ' Brake control stop I control Motor Fixture interface Direction Stop control I power Motor field Status I I i Hydra Load weighing Direction Hydraulic piston Aulo/manual control valve control dispatch u(olmanual Load weighing 1 Car 1 I and group ating I I Car I I j oper I I }operation , Electrical Starter I , ––––– ! i control protective 1 II J devices Across the line Group operation l Resistance 1 I Car I control •Wye-delta I and I I I I group , Hall call I ; 1 ignal I assignment rixlures I Operating device Interface •Fixture interface ' --]npui power/standby power .—. i __-----_ _J ,---------------- ---- FPN Figure 620.2 Control System. motor controllers, driving machine motors, machine brakes, electrical equipment.The minimum working space shall be and motor-generator sets shall not have a circuit voltage in not less than that specified in 110.26(A). excess of 600 volts. Internal voltages of power conversion Where conditions of maintenance and supervision en- equipment and functionally associated equipment, and the sure that only qualified persons examine, adjust, service, operating voltages of wiring interconnecting the equipment, and maintain the equipment, the clearance requirements of shall be permitted to be higher, provided that all such 110.26(A) shall be waived as permitted in 620.5(A) equipment and wiring shall be listed for the higher volt- through (D). ages. Where the voltage exceeds 600 volts, warning labels or signs that read "DANGER — HIGH VOLTAGE" shall (A) Flexible Connections to Equipment. Electrical be attached to the equipment and shall be plainly visible. equipment in(A)(1) through (A)(4)shall be permitted to be provided with flexible leads to all external connections so the Lighting Circuits. Lighting circuits shall comply with that it can be repositioned to meet the clear working space the requirements of Article 410. requirements of 110.26(A): (C) Heating and Air-Conditioning Circuits. Branch cir- (1) Controllers and disconnecting means for dumbwaiters, cuits for heating and air-conditioning equipment located on escalators, moving walks, platform lifts, and stairway the elevator car shall not have a circuit voltage in excess of chairlifts installed in the same space with the driving 600 volts. machine (2) Controllers and disconnecting means for elevators in- 620.4 Live Parts Enclosed. All live parts of electrical ap- paratus in the hoistways, at the landings, in or on the cars of elevators and dumbwaiters, in the wellways or the landings (3) Controllers for door operators of escalators or moving walks, or in the runways and ma- (4) Other electrical equipment installed in the hoistway or chinery spaces of platform lifts and stairway chairlifts shall on the car be enclosed to protect against accidental contact. ($) Guards. Live parts of the electrical equipment are FPN: See 110.27 for guarding of live pans (600 volts, suitably guarded, isolated, or insulated, and the equipment nominal, or less), can be examined, adjusted, serviced, or maintained while 620.5 Working Clearances. Working space shall be pro- energized without removal of this protection. vided about controllers, disconnecting means, and other FPN; See definition of E.rposed in Article 100. 70-518 NATIONAL ELECTRICAL CODE 2(N)8 Edition ARTICLE 020—(ELEVATORS,DUMBWAITERS,ESCALATORS,MOVING WALKS,PLATFORM &STAIRWAY CHAIRLIFTS 620.13 (C) Examination, Adjusting, and Servicing. Electrical (13) Other Wiring. 24 AWG copper. Smaller size listed equipment is not required to be examined, adjusted, ser- conductors shall be permitted. viced, or maintained while energized. 620.13 Feeder and Branch-Circuit Conductors. Con- (D) Low Voltage. Uninsulated parts are at a voltage not ductors shall have an ampacity in accordance with greater than 30 volts rms, 42 volts peak, or 60 volts dc. 620.13(A) through (D). With generator field control, the conductor ampacity shall be based on the nameplate current II. Conductors rating of the driving motor of the motor-generator set that supplies power to the elevator motor. 620.11 Insulation of Conductors. The insulation of con- FPN No. l: The heating of conductors depends on root- ductors shall comply with 620.11(A) through (D). mean-square current values, which, with generator field FPN: One method of determining that conductors are control, are reflected by the nameplate current rating of the flame retardant is by testing the conductors to the VW-I motor-generator driving motor rather than by the rating of (Vertical-Wire) Flame Test in ANSVUL 1581-2001, Refer- the elevator motor, which represents actual but short-time ence Standard for Electrical Wires, Cables, and Flexible and intermittent full-load current values. Cords. FPN No. 2: See Figure 620.13, (A) Hoistway Door Interlock Wiring. The conductors to To supply the hoistway door interlocks from the hoistway riser shall Common feeder 620.13 -------------- be flame retardant and suitable for a temperature of not less Feeder demand factor 620.14 than 200°C (392°F). Conductors shall be Type SF or Motor leeder short- equivalent. circuit and ground- fault protection 820.61(C) (B) Traveling Cables. Traveling cables used as flexible connections between the elevator or dumbwaiter car or counterweight and the raceway shall be of the types of Disconnecting means 620.51 elevator cable listed in Table 400.4 or other approved types. Motor branch-circuit (C) Other Wiring. All conductors in raceways shall have short-circuit and 620.61(D) flame-retardant insulation. ground-fault protection Conductors shall be Type MTW, TF, TFF, TFN, TFFN, THHN,THW,THWN,TW, XHHW, hoistway cable,or any Branch-circuil conductors 620,13 other conductor with insulation designated as flame retar- dant. Shielded conductors shall be permitted if such con- Externallranslormer ductors are insulated for the maximum nominal circuit volt- (optional) Article 450 age applied to any conductor within the cable or raceway system. Motor controller 620.13,620.15 -------------- ------------- (D) Insulation. All conductors shall have an insulation Motor control circuits 620.61(A) voltage rating equal to at least the maximum nominal circuit voltage applied to any conductor within the enclosure, cable, Motor overload or raceway. Insulations and outer coverings that are marked protection 620.61(B) for limited smoke and are so listed shall be permitted. Motor conductors 820.73 620.12 Minimum Size of Conductors.The minimum size Motor Article 430,Part I of conductors, other than conductors that form an integral ---------------M part of control equipment, shall be in accordance with Thermal protection Article 430,Part III 620.12(A) and (B). Figure 620.13 Single-Line Diagram. (A) Traveling Cables. (A) Conductors Supplying Single Motor. Conductors (1) Lighting Circuits. For lighting circuits, 14 AWG cop- supplying a single motor shall have an ampacity not less per,20 AWG copper or larger conductors shall be permitted than the percentage of motor nameplate current determined in parallel, provided the ampacity is equivalent to at least from 430.22(A) and (E). that of 14 AWG copper. FPN: Elevator motor currents, or those of similar functions, may exceed the nameplate value,but because they are inher- (2) Other Circuits. For other circuits, 20 AWG copper, ently intermittent duty and the heating of the motor and 2008 Edition NATIONAL ELECTRICAL CODE 70-519 620.14 ARTICLE 620—ELEVATORS, DUMBWAITERS.ESCALATORS,MOVING WALKS,PLATFORM &STAIRWAY CHAIRLIFTS conductors is dependent on the root-mean-square (rms) led to be less than the nominal rating of the elevator motor, current value,conductors are sized for duty cycle service when the controller inherently limits the available power to as shown in Table 430.22(E). the motor and is marked as power limited. (B) Conductors Supplying a Single Motor Controller. FPN: For controller markings, see 430.8. Conductors supplying a single motor controller shall have an atnpacity not less than the motor controller nameplate current rating, plus all other connected loads, III. Wiring FPN: Motor controller nameplate current rating may he 620.21 Wiring Methods.Conductors and optical fibers lo- derived based on the rms value of the motor current using cated in hoistways, in escalator and moving walk wellways, an intermittent duty cycle and other control system loads,if in platform lifts, stairway chairlift runways, machinery applicable. spaces, control spaces, in or on cars, in machine rooms and (C) Conductors Supplying a Single Power Transformer. control rooms, not including the traveling cables connect- Conductors supplying a single power transformer shall ing the car or counterweight and hoistway wiring, shall be have an atnpacity not less than the nameplate current rating installed in rigid metal conduit, intermediate metal conduit, of the power transformer plus all other connected loads. electrical metallic tubing, rigid nonmetallic conduit, or wireways, or shall be Type MC, MI, or AC cable unless FPN Na. 1: The nameplate current rating of a power trans- otherwise permitted in 620.21{A) through {C). former supplying a motor controller reflects the nameplate current rating of the motor controller at line voltage(trans- (A) Elevators. former primary). FPN No. 2: See Annex D, Example No. D10. (1) Hoistways. (a) Flexible metal conduit, liquidtight flexible metal {D} Conductors Supplying More Than One Motor,Mo- conduit, or liquidtight flexible nonmetallic conduit shall be for Controller, or Power Transformer. Conductors sup- permitted in hoistways between risers and limit switches, plying more than one motor, motor controller, or power interlocks, operating buttons, and similar devices. transformer shall have an atnpacity not less than the sum of (b) Cables used in Class 2power-limited circuits shall the nameplate current ratings of the equipment plus all be permitted to be installed between risers and signal other connected [Dads. The ampere ratings of motors to be equipment and operating devices, provided the cables are used in the summation shall be determined from Table supported and protected from physical damage and are of a 430.22(E), 430.24 and 430,24, Exception No. I. jacketed and flame-retardant type. FPN: See Annex D, Example Nos. D9 and D10. (c) Flexible cords and cables that are components of listed equipment and used in circuits operating at 30 volts 620.14 Feeder Demand Factor. Feeder conductors of less rms or less or 42 volts do or less shall be permitted in ampacity than required by 620.13 shall be permitted, sub- lengths not to exceed 1.8 in (6 ft), provided the cords and ject to the requirements of Table 620.14. cables are supported and protected from physical damage Table 620.14 Feeder Demand Factors for Elevators and are of a jacketed and flame-retardant type. (d) The following wiring methods shall be permitted in Number of Elevators the hoistway in lengths not to exceed 1.8 m (6 ft): on a Single Feeder Demand Factor (1) Flexible metal Conduit (2) Liquidtight flexible metal conduit 1 1.00 (3) Liquidtight flexible nonmetallic conduit 2 0.95 (4) FIexible cords and cables, or conductors grouped to- o ).85 gether and taped or corded, shall be permitted to be 5 0.82 installed without a raceway.They shall be located to be 6 0.79 protected from physical damage and shall be of a 7 0.77 flame-retardant type and shall be part of the following: 8 0.75 a.Listed equipment 9 0.73 10 or more 0.72 b.A driving machine, or c.A driving machine brake FPN: Demand factors are based on 50 percent duty cycle (e) A sump pump or oil recovery pump located in the (i.e., half time on and half time off). pit shall be permitted to be cord connected.The cord shall be a hard usage oil-resistant type, of a length not to exceed 620.15 Motor Controller Rating. The motor controller 1.8 m (6 ft), and shall be located to be protected from rating shall comply with 430.83.The rating shall be permit- physical damage. 70--520 NATIONAL ELECTRICAL CODF. 2008 Edition ARTICLE 620—ELEVATORS,DUMBWAITERS, ESCALATORS,MOVING WALKS, PLATFORM & STAIRWAY CHAIRLIFFS 620.2I (2) Cars. Exception: Liquidtight flexible nonmetallic conduit metric (a) Flexible metal conduit, Liquidtight flexible metal designator 12 (trade size i/x) or larger, as defined in conduit, or liquidtight flexible nonmetallic conduit of metric 356.2(2), shall be permitted to be installed in lengths in designator 12 (trade size ?/s), or larger, not exceeding 1.8 m excess of 1.8 nt (6 ft). (6 ft)in length, shall be permitted on cars where so located as (b) Where motor-generators, machine motors, or to be free from oil and if securely fastened in place. pumping unit motors and valves are located adjacent to or underneath control equipment and are provided with extra- Exception: Liquidtight flexible nonmetallic conduit of met- length terminal leads not exceeding 1.8 m (6 ft) in length, ric designator 12 (trade size 31s), or larger, as defined by such leads shall be permitted to be extended to connect 356.2(2), shall be permitted in lengths in excess of 1.8 m directly to controller terminal studs without regard to the (6 ft). carrying-capacity requirements of Articles 430 and 445. (b) Hard-service cords and junior hard-service cords Auxiliary gutters shall be permitted in machine and control that conform to the requirements of Article 400 (Table rooms between controllers, starters, and similar apparatus. 400.4) shall be permitted as flexible connections between (c) Flexible cords and cables that are components of the fixed wiring on the car and devices on the car doors or listed equipment and used in circuits operating at 30 volts gates. Hard-service cords only shall be permitted as flexible rms or less or 42 volts do or less shall be permitted in connections for the top-of-car operating device or the car- lengths not to exceed 1.8 m (6 ft), provided the cords and top work light. Devices or luminaires shall be grounded by cables are supported and protected from physical damage means of an equipment grounding conductor run with the and are of a jacketed and flame-retardant type, circuit conductors. Cables with smaller conductors and other types and thicknesses of insulation and jackets shall (d) On existing or listed equipment, conductors shall be permitted as flexible connections between the fixed wir- also be permitted to be grouped together and taped or ing on the car and devices on the car doors or gates, if listed corded without being installed in a raceway. Such cable for this use. groups shall be supported at intervals not over 900 mm(3 ft) and located so as to be protected from physical damage. (c) Flexible cords and cables that are components of listed equipment and used in circuits operating at 30 volts (e) Flexible cords and cables in lengths not to exceed rms or less or 42 volts do or less shall be permitted in 1.8 m(6 ft)that are of a flame-retardant type and located to lengths not to exceed 1.8 m (6 ft), provided the cords and be protected from physical damage Shall be permitted in cables are supported and protected from physical damage these rooms and spaces without being installed in a race- and are of a jacketed and flame-retardant type. way.They shall be part of the following: (d) The following wiring methods shall be permitted (1) Listed equipment on the car assembly in lengths not to exceed 1.8 m (6 ft): (2) A driving machine, or (3) A driving machine brake (1) Flexible metal conduit (2) Liquidtight flexible metal conduit (4) Counterweight. The following wiring methods shall (3) Liquidtight flexible nonmetallic conduit be permitted on the counterweight assembly in lengths not (4) Flexible cords and cables, or conductors grouped to- to exceed 1.8 m (6 ft): gether and taped or corded, shall be permitted to be (1) Flexible metal conduit installed without a raceway.They shall be located to be (2) Liquidtight flexible metal conduit protected from physical damage and shall be of a (3) Liquidtight flexible nonmetallic conduit flame-retardant type and shall be part of the following. (4) Flexible cords and cables, or conductors grouped to- a. Listed equipment gether and taped or corded, shall be permitted to be b. A driving machine, or installed without a raceway.They shall be located to be protected from physical damage, shall be of a flame- c. A driving machine brake retardant type, and Shall be part of the following: (3) Within Machine Rooms, Control Rooms, and Ma- a. Listed equipment chinery Spaces and Control Spaces, b. A driving machine, or (a) Flexible metal conduit, liquidtight flexible metal e. A driving machine brake conduit, or Iiquidtight flexible nonmetallic conduit of metric (g) Escalators. designator 12 (trade size '/s), or larger, not exceeding 1.8 m (6 ft)in length, shall be permitted between control panels and (1) Wiring Methods. Flexible metal conduit, liquidtight machine motors, machine brakes, motor-generator sets, dis- flexible metal conduit, or liquidtight flexible nonmetallic connecting means, and pumping unit motors and valves. conduit shall be permitted in escalator and moving walk 2008 Edition NATIONAL-ELECTRICAL CODE 70-521 620.22 ARTICLE 620—ELEVATORS.DUMBWAITERS, ESCALATORS.MOVING WALKS.PLATFORM &STAIRWAY CHAIRL1FrS wellways. Flexible metal conduit or liquidtight flexible the elevator machine room or control room/machinery conduit of metric designator 12 (trade size 3 18) shall be space or control space. permitted in lengths not in excess of 1.8 in (6 ft). Required lighting shall not be connected to the load side of a ground-fault circuit interrupter. Exception: Metric designator 12 (trade size -1/8), nominal, or larger liquidtight flexible nonmetallic conduit, as defined (B) Air-Conditioning and Heating Source. A dedicated in 356.2(2), shall be pennitted to be installed in lengths in branch circuit shall supply the air-conditioning and heat- excess of 1.8 in (6 ft). ing units on each elevator car. The overcurrent device (2) Class 2 Circuit Cables. Cables used in Class 2 power- protecting the branch circuit shall be located in the el- limited circuits shall be permitted to be installed within evator machine room or control room/machinery space escalators and moving walkways, provided the cables are or control space. supported and protected from physical damage and are of a jacketed and flame-retardant type. 620.23 Branch Circuits for Machine Room or Control Room/Machinery Space or Control Space Lighting and (3) Flexible Cords. Hard-service cords that conform to the Receptacle(s). requirements of Article 400 (Table 400.4) shall be permit- ted as flexible connections on escalators and moving walk (A) Separate Branch Circuit. A separate branch circuit control panels and disconnecting means where the entire shall supply the machine room or control room/machinery control panel and disconnecting means are arranged for space or control space lighting and receptacles}. removal From machine spaces as permitted in 620.5. Required lighting shall not be connected to the load side of a ground-fault circuit interrupter, (C) Platform Lifts and Stairway Chairlift Raceways. (B) Lighting Switch. The machine room or control (1) Wiring Methods. Flexible metal conduit or liquidtight room/machinery space or control space lighting switch flexible metal conduit shall be permitted in platform lifts shall be located at the point of entry. and stairway chairlift runways and machinery spaces. Flex- ible metal conduit or liquidtight flexible conduit of metric (C) Duplex: Receptacle. At least one 125-volt, single- designator 12 (trade size 3/x) shall be permitted in lengths phase, 15- or 20-ampere duplex receptacle shall be pro- not in excess of 1.8 to (6 ft). vided in each machine room or control room and machin- ery space or control space. Exception: Metric designator 12 (trade size YN) or larger liquidtight flexible nonmetallic conduit, as defined in FPN: See ASME A17.1-2004. Safety Code for Elevators 356.2(2), shrill be permitted to be installed in lengths in and Escalatory, for illumination levels. excess 'f 1.8 m (6 ft}. 620.24 Branch Circuit for Hoistway Pit Lighting and (2) Class 2 Circuit Cables.Cables used in Class 2 power- Receptacle(s). limited circuits shall be permitted to be installed within platform lifts and stairway chairlift runways and machinery (A) Separate Branch Circuit. A separate branch circuit spaces, provided the cables are supported and protected shall supply the hoistway pit lighting and receptacle(s). from physical damage and are of a jacketed and flame- Required lighting shall not be connected to the load side of a ground-fault circuit interrupter. retardant type. (3) Flexible Cords and Cables. Flexible cords and cables (B) Lighting Switch. The lighting switch shall be so lo- that are components of listed equipment and used in cir- cated as to be readily accessible from the pit access door. cnits operating at 30 volts rms or less or 42 volts de or less (C) Duplex Receptacle. At least one 125-volt, single- shall be permitted in lengths not to exceed 1.8 m (6 ft), phase, 15- or 20-ampere duplex receptacle shall be pro- provided the cords and cables are supported and protected vided in the hoistway pit, from physical damage and are of a jacketed and flame- retardant type. FPN: See ASME A 17.1-2004, Safety Code for Elevators and Escalators, for illumination levels. 620.22 Branch Circuits for Car Lighting, Receptacle(s), Ventilation, Heating, and Air-Conditioning. 620.25 Branch Circuits for Other Utilization Equipment. (A) Car Light Source.A separate branch circuit shall sup- (A) Additional Branch Circuits. Additional branch cir- ply the car lights, receptacle(s), auxiliary lighting power cuit(s) shall supply utilization equipment not identified in source, and ventilation on each elevator car. The overcur- 620.22, 620.2:3, and 620.24. Other utilization equipment rent device protecting the branch circuit shall be located in shall be restricted to that equipment identified in 620.1. 74-522 NATIONAL ELECTRICAL CODE 2009 Edition ARTICLE 620—ELEVATORS.DUMBWAITERS, ESCALATORS,MOVING WALKS, PLATFORM &STAIRWAY CHAIRLIFI'S 620A1 (B) Overcurrent Devices. The overcurrent devices pro- with the car, for lighting, heating, air conditioning, and venti- tecting the branch circuit(s) shall be located in the elevator lating the elevator car, for fire detecting systems, for pit sump machinery room or control room/machinery space or con- pumps, and for heating, lighting,and ventilating the hoistway, trol space. shall be permitted inside the hoistway,machine rooms,control rooms, machinery spaces, and control spaces. IV. Installation of Conductors (B) Lightning Protection. Bonding of elevator rails (car 620.32 Metal Wireways and Nonmetallic Wireways. and/or counterweight) to a lightning protection system The sum of the cross-sectional area of the individual con- grounding down conductor(s) shall be permitted.The light- ductors in a wireway shall not be more than 50 percent of ning protection system grounding down conductor(s) shall the interior cross-sectional area of the wireway. not be located within the hoistway. Elevator rails or other Vertical runs of wireways shall be securely supported at hoistway equipment shall not be used as the grounding intervals not exceeding 4.5 m (I 5 ft) and shall have not more down conductor for lightning protection systems. than one joint between supports. Adjoining wireway sections FPN: See 250.106 for bonding requirements. For further shall be securely fastened together to provide a rigid joint. information, see NFPA 780-2008, Standard for the Instal- lation of Lightning Protection Systems. 620.33 Number of Conductors in Raceways.The sum of the cross-sectional area of the individual conductors in {C) Main Feeders. Main feeders for supplying power to elevators and dumbwaiters shall be installed outside the raceways shall not exceed 40 percent of the interior cross- hoistway unless as follows: sectional area of the raceway, except as permitted in 620.32 for wireways. (I) By special permission, feeders for elevators shall be permitted within an existing hoistway if no conductors 620.34 Supports. Supports for cables or raceways in a are spliced within the hoistway. hoistway or in an escalator or moving walk wellway or (2) Feeders shall be permitted inside the hoistway for el- platform lift and stairway chairlift runway shall be securely evators with driving machine motors located in the fastened to the guide rail; escalator or moving walk truss; hoistway or on the car or counterweight. or to the hoistway, wellway, or runway construction. 620.38 Electrical Equipment in Garages and Similar 620.35 Auxiliary Gutters. Auxiliary gutters shall not be Occupancies. Electrical equipment and wiring used for el- subject to the restrictions of 366.12(2)covering length or of evators, dumbwaiters, escalators, moving walks, and plat- 366.22 covering number of conductors. form lifts and stairway chairlifts in garages shall comply with the requirements of Article 511. 620.36 Different Systems in One Raceway or Traveling FPN: Garages used for parking or storage and where no Cable. Optical fiber cables and conductors for operating repair work is done in accordance with 511.3 are not devices, operation and motion control, power, signaling, classified. fire alarm, lighting, heating, and air-conditioning circuits of 600 volts or less shall be permitted to be run in the same V. Traveling Cables traveling cable or raceway system if all conductors are in- sulated for the maximum voltage applied to any conductor 620.41 Suspension of Traveling Cables. Traveling cables within the cables or raceway system and if all live parts of shall be suspended at the car and hoistways'ends, or coun- the equipment are insulated from ground for this maximum terweight end where applicable, so as to reduce the strain voltage. Such a traveling cable or raceway shall also be on the individual copper conductors to a minimum. permitted to include shielded conductors and/or one or Traveling cables shall be supported by one of the fol- more coaxial cables if such conductors are insulated for the lowing means: maximum voltage applied to any conductor within the (1) By their steel supporting member(s) cable or raceway system. Conductors shall be permitted to (2) By looping the cables around supports for unsupported be covered with suitable shielding for telephone, audio, lengths less than 30 m (100 ft) video, or higher frequency communications circuits. (3) By suspending from the supports by a means that au- 620.37 Wiring in Hoistways, Machine Rooms, Control tomatically tightens around the cable when tension is Rooms, Machinery Spaces, and Control Spaces. increased for unsupported lengths up to 60 in (200 ft) (A) Uses Permitted. Only such electrical wiring, raceways, FPN: Unsupported length for the hoistway suspension means is that length of cable as measured from the point of and cables used directly in connection with the elevator or suspension in the hoistway to the bottom of the loop, with dumbwaiter, including wiring for signals, for communication the elevator car located at the bottom landing.Unsupported 2008 Edition NATIONAL ELECTRICAL CODE 70-523 620.42 ARTICLE 620—ELEVATORS.DUMBWArrERS, ESCALATORS.MOVING WALKS. PLATFORM &STAIRWAY CHAIRLIFfS length for the car suspension means is that length of cable breaker used as the disconnecting means and shall remain as measured from the point of suspension on the car to the in place with or without the lock installed. Portable means bottom of the loop, with the elevator car located at the tap landing. for adding,a lock to the switch or circuit breaker shall not be permitted as the means required to be installed at and 620.42 Hazardous (Classified) Locations. In hazardous remain with the equipment. (classified) locations, traveling cables shall be of a type The disconnecting means shall be a listed device. approved for hazardous (classified) locations and shall FPN: For additional information, see ASME A17.1-2004, comply with 501.140, 502.140, or 503.140, as applicable. Safer• Cade for Elevators and Escalators. 620.43 Location of and Protection for Cables. Traveling Exception No. 1: Where an individual branch circuit sup- cable supports shall be located so as to reduce to a mini- plies a platform lift, the disconnecting means required b}• mum the possibility of damage due to the cables coming in 620.51(C)(4)shall be permitted to campy with 430.109(C). contact with the hoistway construction or equipment in the This disconnecting means shall be listed and shall he ca- hoistway. Where necessary, suitable guards shall be pro- pable of being locked in the open position. The provision vided to protect the cables against damage. for locking or adding a lock to the disconnecting means shall be installed on or at the switch or circuit breaker used 620.44 Installation of Traveling Cables.Traveling cables as the disconnecting means and shall remain in place with that are suitably supported and protected from physical or without the lock installed. Portable means for adding a damage shall be permitted to be run without the use of a lock to the switch or circuit breaker shall not be permitted raceway in either or both of the following: as the means required to be installer)at and remain with the equipment. (a) When used inside the hoistway, on the elevator car, Exception No. 2: Where an individual branch circuit sup- hoistway wall,counterweight,or controllers and machinery that are located inside the hoistway,provided the cables are plies a stairway chairlift, the stairway chairlift shall be in the original sheath. permitted to be cord-and-plug-connected, provided it com- (b) From inside the hoistway,to elevator controller en- plies with 422.16(A) and the cord does not exceed 1.8 m closures and to elevator car and machine room, control (6,t') in length. room, machinery space, and control space connections that (B) Operation. No provision shall be made to open or are Iocated outside the hoistway for a distance not exceed- close this disconnecting means from any other part of the ing 1.8 m (6 ft)in length as measured from the first point of premises. If sprinklers are installed in hoistways, machine support on the elevator car or hoistway wall, or counter- rooms, control rooms, machinery spaces, or control spaces, weight where applicable, provided the conductors are the disconnecting means shall be permitted to automatically grouped together and taped or corded, or in the original open the power supply to the affected elevator(s) prior to sheath. These traveling cables shall be permitted to be con- the application of water. No provision shall be made to tinued to this equipment. automatically close this disconnecting means. Power shall only be restored by manual means. Vi. Disconnecting Means and Control FPN: To reduce hazards associated with water on live el- 620.51 Disconnecting Means. A single means for discon- evator electrical equipment. necting all ungrounded main power supply conductors for (C) Location. The disconnecting means shall be located each unit shall be provided and be designed so that no pole where it is readily accessible to qualified persons. can be operated independently.Where multiple driving ma- chines are connected to a single elevator, escalator, moving (1) On Elevators Without Generator Field Control. On walk, or pumping unit, there shall be one disconnecting elevators without generator field control, the disconnecting means to disconnect the motor(s) and control valve operat- means shall be located within sight of the motor controller. ing magnets. Where the motor controller is located in the elevator hoist- The disconnecting means for the main power supply way, the disconnecting means required by 620.51(A) shall conductors shall not disconnect the branch circuit required be located in a machinery space, machine room, control in 620.22, 620.23, and 620.24, space or control room outside the hoistway; and an addi- tional,non-fused enclosed externally operable motor circuit (A) Type. The disconnecting means shall be an enclosed switch capable of being locked in the open position to dis- externally operable fused motor circuit switch or circuit connect all ungrounded main power-supply conductors breaker capable of being locked in the open position. The shall be located within sight of the motor controller. The provision for locking or adding a lock to the disconnecting additional switch shall be a listed device and shall comply means shall be installed on or at the switch or circuit with 620.91(Q. 70-524 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 620—ELEVATORS, DUMBWAITERS, ESCALATORS,MOVING WALKS, PLATFORM &STAIRWAY CHAIRLIFTS 620,54 The provision for locking or adding a lock:to the dis- (B) Warning Sign for Multiple Disconnecting Means. connecting means, required by this section, shall be in- Where multiple disconnecting means are used and parts of stalled on or at the switch or circuit breaker used as the the controllers remain energized from a source other than disconnecting; means and shall remain in place with or the one disconnected, a warning sign shall be mounted on without the lock installed. Portable means for adding a lock or next to the disconnecting means. The sign shall be to the switch or circuit breaker shall not be permitted. clearly legible and shall read as follows: Driving machines or motion and operation controllers not within sight of the disconnecting means shall be pro- WARNING vided with a manually operated switch installed in the con- PARTS OF THE CONTROLLER ARE NOT trol circuit to prevent starting. The manually operated DE-ENERGIZED BY THIS SWITCH. switch(es) shall be installed adjacent to this equipment. (C) Interconnection Multicar Controllers. Where inter- Where the driving machine of an electric elevator or the connections between controllers are necessary for the op- hydraulic machine of a hydraulic elevator is located in a eration of the system on multicar installations that remain remote machine room or remote machinery space, a single energized from a source other than the one disconnected, a means for disconnecting all ungrounded main power- warning sign in accordance with 620.52(B) shall be supply conductors shall be provided and be capable of be- mounted on or next to the disconnecting means, ing locked in the open position. (2) On Elevators with Generator Field Control. On el- 620.53 Car Light, Receptacle(s), and Ventilation Dis- evators with generator field control, the disconnecting connecting Means. Elevators shall have a single means for means shall be located within sight of the motor controller disconnecting all ungrounded car light, receptacle(s), and for the driving motor of the motor-generator set. Driving ventilation power-supply conductors for that elevator car. machines, motor-generator sets, or motion and operation The disconnecting means shall be an enclosed exter- controllers not within sight of the disconnecting means shall nally operable fused motor circuit switch or circuit breaker be provided with a manually operated switch installed in the capable of being locked in the open position and shall be control circuit to prevent starting. The manually operated located in the machine room or control room for that eleva- switch(es) shall be installed adjacent to this equipment. for car. The provision for locking or adding a lock to the Where the driving machine or the motor-generator set is disconnecting means shall be installed on or at the switch located in a remote machine room or remote machinery or circuit breaker used as the disconnecting means and shall space, a single means for disconnecting all ungrounded remain in place with or Without the lock installed Portable main power-supply conductors shall be provided and be means for adding a lock to the switch or circuit breaker capable of being locked in the open position. Shall not be permitted as the means required to be installed at and remain with the equipment. Where there is no ma- (3) On Escalators and Moving Walks. On escalators and chine room or control room, the disconnecting means shall moving walks, the disconnecting means shall be installed in be located in a machinery space or control space outside the the space where the controller is located. hoistway that is readily accessible to only qualified persons. (4) On Platform Lifts and Stairway Chairlifts. On plat- Disconnecting means shall be numbered to correspond form lifts and stairway chairlifts, the disconnecting means to the identifying number of the elevator car whose light shall be located within sight of the motor controller. source they control. The disconnecting means shall be provided with a sign (D) Identification and Signs. Where there is more than to identify the location of the supply side overcurrent pro- one driving machine in a machine room, the disconnecting tective device. means shall be numbered to correspond to the identifying number of the driving machine that they control. 620.54 Heating and Air-Conditioning Disconnecting The disconnecting means shall be provided with a sign Means. Elevators shall have a single means for disconnect- to identify the location of the supply side overcurrent pro- ing all ungrounded car heating and air-conditioning power- tective device. supply conductors for that elevator car. The disconnecting means shall be an enclosed exter- nally operable fused motor circuit switch or circuit breaker (A) Single-Car and Multicar Installations. On single-car capable of being locked in the open position and shall be and multicar installations, equipment receiving electrical located in the machine room or control room for that eleva- power from more than one source shall be provided with a for car. The provision for locking or adding a lock to the disconnecting means for each source of electrical power. disconnecting means shall be installed on or at the switch The disconnecting means shall be within sight of the equip- or circuit-breaker used as the disconnecting means and shall ment served, remain in place with or without the lock installed. Portable 2008 Edition NATIONAL ELECTRICAL,CODE 70-525 620.55 ARTICLE 620—ELEVATORS,DUMBWAITERS, ESCALATORS,MOVING WALKS, PLATFORM &STAIRWAY CHAIRLIFTS means for adding a lock to the switch or circuit breaker motor-generators used with generator field control shall be shall not be permitted as the means required to be installed rated as intermittent. Such motors shall be permitted to be at and remain with the equipment. Where there is no ma- protected against overload in accordance with 430.33. chine room or control room, the disconnecting means shall be located in a machinery space or control space outside the (2) Duty Rating on Escalator Motors. Duty an escalator hoistway that is readily accessible to only qualified persons. and moving walk driving machine motors shall be rated as Where there is equipment for more than one elevator continuous. Such motors shall be protected against over car in the machine room, the disconnecting means shall be load in accordance with 430.32. numbered to correspond to the identifying number of the (3) Overload Protection.Escalator and moving walk driv- elevator car whose heating and air-conditioning source they ing machine motors and driving motors of motor-generator control, sets shall be protected against running overload as provided The disconnecting means shall be provided with a sign in Table 430.37. to identify the location of the supply side overcurrent pro- tective device. (4) Duty Rating and Overload Protection on Platform Lift and Stairway Chairlift Motors. Duty on platform lift 620.55 Utilization Equipment Disconnecting Means. and stairway chairlift driving machine motors shall be rated Each branch circuit for other utilization equipment shall as intermittent. Such motors shall be permitted to be pro- have a single means for disconnecting all ungrounded con- tected against overload in accordance with 430.33. ductors.The disconnecting means shall be capable of being FPN: For further information, we 430.44 for orderly locked in the open position and shall be located in the shutdown. machine room or control room/machine space or control space. The provision for locking or adding a lock to the (C) Motor Feeder Short-Circuit and Ground-Fault Pro- disconnecting means shall be installed on or at the switch tection. Motor feeder short-circuit and ground-fault protec- or circuit breaker used as the disconnecting means and shall tion shall be as required in Article 430, Part V. remain in place with or without the lock installed. Portable Ground- means for adding a lock to the switch or circuit breaker (D) Motor Branch-Circuit Short-Circuit and Ground- shaIl not be permitted as the means required to be installed Fault Protection. Motor branch-circuit short-circuit and at and remain with the equipment. ground-fault protection shall be as required in Article 430, Where there is more than one branch circuit for other Part IV. utilization equipment, the disconnecting means shall be numbered to correspond to the identifying number of the 620.62 Selective Coordination. Where more than one equipment served. The disconnecting means shall be pro- driving machine disconnecting means is supplied by a vided with a sign to identify the location of the supply side single feeder, the overcurrent protective devices in each overcurrent protective device. disconnec ting means shall be selectively coordinated with any other supply side overcurrent protective devices. V11. Overcurrent Protection V111. Machine Rooms, Control Rooms, Machinery 620.61 Overcurrent Protection. Overcurrent protection Spaces, and Control Spaces shall be provided in accordance with 620.6](A) through (D). 620.71 Guarding Equipment. Elevator, dumbwaiter, e.%_ (A) Operating Devices and Control and Signaling Cir- calator, and moving walk driving machines; motor- cuits. Operating devices and control and signaling circuits generator sets; motor controllers; and disconnecting means shall be protected against overcurrent in accordance with shall be installed in a room or space set aside for that the requirements of 725.43 and 725.45. purpose unless otherwise permitted in 620.71(A) or (B). Class 2 power-limited circuits shall be protected against The room or space shall be secured against unauthorized overcurrent in accordance with the requirements of Chapter access. 9, Notes to Tables I I(A) and 11(B). (A) Motor Controllers. Motor controllers shall be permit- (B) Overload Protection for Motors. Motor and branch- ted outside the spaces herein specified, provided they are in circuit overload protection shall conform to Article 430, enclosures with doors or removable panels that are capable Part III, and (13)(1) through (13)(4). of being locked in the closed position and the disconnecting means is located adjacent to or is an integral part of the (1) Duty Rating on Elevator, Dumbwaiter, and Motor- motor controller. Motor controller enclosures for escala- Generator Sets Driving Motors. Duty on elevator and for or moving walks shall be permitted in the balustrade dumbwaiter driving machine motors and driving motors of on the side located away from the moving steps or moving 70-526 NATIONAL ELECTRICAL Coal: 2(N)8 Edition ARTICLE 625—ELECTRIC VEHICLE CHARGING SYSTEM 625.2 treadway. If the disconnecting means is an integral part of the (A) Regenerative Power. For elevator systems that regen- motor controller, it shall be operable without opening the en- erate power back into the power source that is unable to closure. absorb the regenerative power under overhauling elevator load conditions, a means shall be provided to absorb this (B) Driving Machines. Elevators with driving machines power. located on the car, on the counterweight,or in the hoistway, and driving machines for dumbwaiters, platform lifts, and (B) Other Building Loads. Other building loads, such as stairway lifts, shall be permitted outside the spaces herein power and lighting,shall be permitted as the energy absorp- specified. tion means required in 620.91(A), provided that such loads are automatically connected to the emergency or standby power system operating the elevators and are large enough IX. Grounding to absorb the elevator regenerative power. 620.81 Metal Raceways Attached to Cars. Metal race- ways, Type MC cable, Type MI cable, or Type AC cable (C) Disconnecting Means. The disconnecting means re- attached to elevator cars shall be bonded to metal parts of the quired by b20.51 shall disconnect the elevator from both car that are bonded to the equipment grounding conductor. the emergency or standby power system and the normal power system. 620.82 Electric Elevators. For electric elevators, the Where an additional power source is connected to the frames of all motors, elevator machines, controllers, and load side of the disconnecting means, the disconnecting the metal enclosures for all electrical equipment in or on means required in 620.51 shall be provided with an auxil- the car or in the hoistway shall be bonded in accordance iary contact that is positively opened mechanically, and the with Article 250, Parts V and VII. opening shall not be solely dependent on springs.This con- tact shall cause the additional power source to be discon- 620.83 Nonelectric Elevators. For elevators other than nected from its load when the disconnecting means is in the electric having any electrical conductors attached to the car, open position. the metal frame of the car, where normally accessible to persons, shall be bonded in accordance with Article 250, Parts V and VII. 620.84 Escalators, Moving Walks, Platform Lifts, and ARTICLE 625 Stairway Chairlifts. Escalators, moving walks, platform Electric Vehicle Charging System lifts, and stairway chairlifts shall comply with Article 250. I. General 620.85 Ground-Fault Circuit-Interrupter Protection for Personnel. Each 125-volt,single-phase, 15-and 20-ampere 625.1 Scope. The provisions of this article cover the elec- receptacle installed in pits, in hoistways, on elevator car trical conductors and equipment external to an electric ve- tops, and in escalator and moving walk wellways shall be hicle that connect an electric vehicle to a supply of electric- of the ground-fault circuit-interrupter type. ity by conductive or inductive means,and the installation of All 125-volt, single-phase, 15- and 20-ampere recep- equipment and devices related to electric vehicle charging. tacles installed in machine rooms and machinery spaces FPN: For industrial trucks, see NFPA 505-2006, Fire shall have ground-fault circuit-interrupter protection for Safety Standard for Powered Industrial Trucks Including personnel. Type Designations, Areas of Use, Conversions, Muinte- A single receptacle supplying a permanently installed nonce, and Operation. sump pump shall not require ground-fault circuit- interrupter protection. 625.2 Definitions. Electric Vehicle. An automotive-type vehicle for on-road X. Emergency and Standby Power Systems use,such as passenger automobiles,buses,trucks,vans,neigh- borhood electric vehicles, and the like, primarily powered by 620.91 Emergency and Standby Power Systems. An el- an electric motor that draws current from a rechargeable stor- evator(s)shall be permitted to be powered by an emergency age battery, fuel cell, photovoltaic array, or other source of or standby power system. electric current. For the purpose of this article,electric motor- cycles and similar type vehicles and off road, self-propelled FPN: See ASME A17.1-2044, Safety Code far Elevators and Escalators, and CSA B44-44,Elevator and Escalator electric vehicles, such as industrial trucks, hoists, lifts, trans- Electrical Equipment Certification Standard 2,27.2, for ad- ports, golf carts, airline ground support equipment, tractors, ditional information. boats, and the like, are not included. 2008 Edition NATIONAL ELECTRICAL CODF 70-527 625.3 ARTICLE 625—ELECTRIC VEHICLE CHARGING SYSTEM Electric Vehicle Connector. A device that, by insertion (B) Noninterchangeability. The electric vehicle coupler into an electric vehicle inlet, establishes an electrical con- shall have a configuration that is noninterchangeable with nection to the electric vehicle for the purpose of charging wiring devices in other electrical systems, Nongrounding- and information exchange. This device is part of the elec- type electric vehicle couplers shall not be interchangeable tric vehicle coupler. with grounding-type electric vehicle couplers. Electric Vehicle Coupler. A mating electric vehicle inlet (C) Construction and Installation. The electric vehicle and electric vehicle connector set. coupler shall be constructed and installed so as to guard Electric Vehicle Inlet. The device on the electric vehicle against inadvertent contact by persons with parts made live into which the electric vehicle connector is inserted for from the electric vehicle supply equipment or the electric charging and information exchange. This device is part of vehicle battery. the electric vehicle coupler. For the purposes of this Code, (p) Unintentional Disconnection. The electric vehicle the electric vehicle inlet is considered to be part of the coupler shall be provided with a positive means to prevent electric vehicle and not part of the electric vehicle supply unintentional disconnection. equipment. Electric Vehicle Nonvented Storage Battery. A hermeti- (E) Grounding Pole. The electric vehicle coupler shall be cally scaled battery, comprised of one or more rechargeable provided with a grounding pole, unless part of a system electrochemical cells, that has no provision for the release identified and listed as suitable for the purpose in accor- of excessive gas pressure, or for the addition of water or dance with Article 250, electrolyte.or for external measurements of electrolyte spe- (F) Grounding Pole Requirements.If a grounding pole is cific gravity. provided, the electric vehicle coupler shall be so designed Electric Vehicle Supply Equipment. The conductors, in- that the grounding pole connection is the first to make and cluding the ungrounded, grounded, and equipment ground- the last to break contact. ing conductors and the electric vehicle connectors, attach- ment plugs, and all other fittings, devices, power outlets, or III. Equipment Construction apparatus installed specifically for the purpose of delivering energy from the premises wiring to the electric vehicle. 625.I3 Electric Vehicle Supply Equipment. Electric ve- hicle supply equipment rated at 125 volts, single phase, 15 Personnel Protection System, A system of personnel or 20 amperes or part of a system identified and listed as protection devices and constructional features that when suitable for the purpose and meeting the requirements of used together provide protection against electric shock 625.18, 625.19, and 625.29 shall be permitted to be cord- of personnel. and-plug-connected. All other electric vehicle supply equipment shall be permanently connected and fastened in 625.3 Other Articles. Wherever the requirements of other place. This equipment shall have no exposed live parts. articles of this Cade and Article 625 differ,the requirements of Article 625 shall apply. 625.14 Rating. Electric vehicle supply equipment shall have sufficient rating to supply the load served. For the 625.4 Voltages. Unless other voltages are specified, the purposes of this article,electric vehicle charging loads shall nominal ac system voltages of 120, 1201240, 208YAM be considered to be continuous loads. 240,480Y/277,480, 600Y1347, and 600 volts shall be used to supply equipment covered by this article. 625.15 Markings. The electric vehicle supply equipment shall comply with 625.15(A) through (C). 625.5 Listed or Labeled. All electrical materials, devices, fittings, and associated equipment shall be listed or labeled. (A) General. All electric vehicle supply equipment shall be marked by the manufacturer as follows: II. Wiring Methods FOR USE WITH ELECTRIC VEHICLES 625.9 Electric Vehicle Coupler. The electric vehicle cou- (B) Ventilation Not Required.Where marking is required pler shall comply with 625.9(A) through (F). by 625.29(C), the electric vehicle supply equipment shall be clearly marked by the manufacturer as follows: (A) Polarization.The electric vehicle coupler shall be po- VENTILATION NOT REQUIRED larized unless part of a system identified and listed as suit- The marking shall be located so as to be clearly visible able for the purpose. after installation. 70-528 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 625—ELECTRIC VEHICLE CHARGING SYSTEM 625.29 (C) Ventilation Required. Where marking is required by rating of not less than the sum of the noncontinuous loads 625.29(D), the electric vehicle supply equipment shall be plus 125 percent of the continuous loads, clearly marked by the manufacturer, "Ventilation Re- quired." The marking shall be located so as to be clearly 625.22 Personnel Protection System.The electric vehicle visible after installation, supply equipment shall have a listed system of protection against electric shock of personnel. The personnel protec- 625.16 Means of Coupling. The means of coupling to the tion system shall be composed of listed personnel protec- electric vehicle shall be either conductive or inductive. At- tion devices and constructional features. Where cord-and- tachment plugs,electric vehicle connectors, and electric ve- plug-connected electric vehicle supply equipment is used, the hicle inlets shall be listed or labeled for the purpose. interrupting device of a listed personnel protection system shall be provided and shall be an integral part of the attach- 625.17 Cable.The electric vehicle supply equipment cable ment plug or shall be located in the power supply cable not shall be Type EV, EVJ, EVE, EVJE, EVT, or EVJT flexible more than 300 mm (12 in,) from the attachment plug. cable as specified in Article 400 and Table 400.4. Ampaci- ties shall be as specified in Table 400.5(A) for 10 AWG and 625.23 Disconnecting Means. For electric vehicle supply smaller, and in Table 400.5($) for S AWG and larger. The equipment rated more than 60 amperes or more than 150 overall length of the cable shall not exceed 7.5 m (25 ft) volts to ground, the disconnecting means shall be provided unless equipped with a cable management system that is and installed in a readily accessible location. The discon- listed as suitable for the purpose. Other cable types and necting means shall be capable of being locked in the open assemblies listed as being suitable for the purpose, includ- position. The provision for locking or adding a lock to the ing optional hybrid communications, signal, and optical fi- disconnecting means shall be installed on or at the switch ber cables, shall be permitted. or circuit breaker used as the disconnecting means and shall remain in place with or without the lock installed.Portable 625.18 Interlock. Electric vehicle supply equipment shall means for adding a lock to the switch or Circuit breaker be provided with an interlock that de-energizes the electric shall not be permitted. vehicle connector and its cable whenever the electrical con- nector is uncoupled from the electric vehicle. An interlock 625.25 Loss of Primary Source. Means shall be provided shall not be required for portable cord-and-plug-connected such that, upon loss of voltage from the utility or other electric vehicle supply equipment intended for connection electrical systern(s), energy cannot be back fed through the to receptacle outlets rated at 125 volts, single phase, 15 and electric vehicle and the supply equipment to the premises 20 amperes. wiring system unless permitted by 625.26. 625.19 Automatic De-Energization of Cable. The elec- 625.26 Interactive Systems. Electric vehicle supply tric vehicle supply equipment or the cable-connector com- equipment and other parts of a system, either on-board or bination of the equipment shall be provided with an auto- off-board the vehicle, that are identified for and intended to matic means to de-energize the cable conductors and be interconnected to a vehicle and also serve as an optional electric vehicle connector upon exposure to strain that standby system or an electric power production source or could result in either cable rupture or separation of the provide for bi-directional power feed shall be listed as suit- cable from the electric connector and exposure of live parts, able for that purpose. When used as an optional standby Automatic means to de-energize the cable conductors and system, the requirements of Article 702 shall apply, and electric vehicle connector shall not be required for portable when used as an electric power production source, the re- cord-and-plug-connected electric vehicle supply equipment quirements of Article 705 shall apply. intended for connection to receptacle outlets rated at 125 volts, single phase, 15 and 20 amperes. V. Electric Vehicle Supply Equipment Locations IV. Control and Protection 625.28 Hazardous (Classified) Locations. Where electric vehicle supply equipment or wiring is installed in a hazard- 625.21 Overcurrent Protection. Overcurrent protection ous (classified) location, the requirements of Articles 500 for feeders and branch circuits supplying electric vehicle through 516 shall apply. supply equipment shall be sized for continuous duty and shall have a rating of not less than 125 percent of the 625.29 Indoor Sites. Indoor sites shall include, but not be maximum load of the electric vehicle supply equipment. limited to,integral,attached, and detached residential garages; Where noncontinuous loads are supplied from the same enclosed and underground parking structures; repair and non- feeder or branch circuit, the overcurrent device shall have a repair commercial garages; and agricultural buildings. 2008 Edition NATIONAL ELECTRICAL.COIF. 70-529 625.29 ARTICLE 625-ELECTRIC VEHICLE CHARGING SYSTEM (A) Location. The electric vehicle supply equipment (2) Other Values. For supply voltages and currents other shall be located to permit direct connection to the elec- than specified in Table 625.29(D)(1)or Table 625.29(D)(2), tric vehicle. the minimum ventilation requirements shall be calculated by means of the following general formulas as applicable: (B) Height. Unless specifically listed for the purpose and (1} Single base: Ventilation se c per in cubic the coupling means of the electric vehicle supply g p ' smglc pha meters P equipment shall be stored or located at a height of not less minute (m-/min) _ than 450 mm (18 in.) and not more than 1.2 m (4 ft) above (volts)(amperes) the floor level. 1718 (C) Ventilation Not Required. Where electric vehicle Ventilation single ,huse in cubic feet per minute (cfm) - nonvented storage batteries are used or where the electric vehicle supply equipment is listed or labeled as suitable for (volts)(amperes) charging electric vehicles indoors without ventilation and 48.7 marked in accordance with 625.15(B), mechanical ventila- tion shall not be required. (2} Three phase: Ventilation three phase to cubic meters per minute {m3lmin} _ (D) Ventilation Required. Where the electric vehicle sup- ply equipment is listed or labeled as suitable for charging 1.732{volts){amperes) electric vehicles that require ventilation for indoor charging, 1718 and is marked in accordance with 625.15(0),mechanical ven- tilation, such as a fan, shall be provided.The ventilation shall Ventilation,hrce phase in cubic feet per minute (cfm) include both supply and exhaust equipment and shall be per- 1.732(volts)(amperes) manently installed and located to intake from, and vent di- rectly to, the outdoors. Positive pressure ventilation systems 48'7 shall be permitted only in buildings or areas that have been (3) Engineered Systems. For an electric vehicle supply specifically designed and approved for that application. Me- equipment ventilation system designed by a person quali- chanical ventilation requirements shall be determined by one fied to perform such calculations as an integral part of a of the methods specified in 625.29(D)(1) through (13)(4). building's total ventilation system,the minimum ventilation (1) Table Values. For supply voltages and currents speci- requirements shall be permitted to be determined per cal- fied in Table 625.29(D)(1) or Table 625.29(D)(2),the mini- culations specified in the engineering study. mum ventilation requirements shall be as specified in Table (4) Supply Circuits. The supply circuit to the mechanical 625.29(D)(1) or Table 625.29(D)(2) for each of the total ventilation equipment shall be electrically interlocked number of electric vehicles that can be charged at one time. with the electric vehicle supply equipment and shall remain Table 625.29(D)(1) Minimum Ventilation Required in Cubic Meters per Minute(m'/min) for Each of the Total Number of Electric Vehicles That Can Be Charged at One Time Branch-Circuit Voltage Branch- Single Phase 3 Phase Circuit Ampere 240 V or 208 V or 480 V or 600 V or Rating 120 V 208 V 1201140 V 208Y1120 V 240 V 480Y/277 V 600Y1347 V 15 1.1 1.8 2.1 - - - 20 1.4 2.4 2.8 4.2 4.8 9.7 12 30 2.1 3.6 4.2 6.3 7.2 15 is 40 2.8 4.8 5.6 8.4 9.7 19 24 50 3.5 6.1 7.0 10 12 24 30 60 4.2 7.3 8.4 13 15 29 36 100 7.0 12 14 21 24 48 60 150 - - - 31 36 73 91 200 - - - 42 48 97 120 250 - - - 52 60 120 150 300 - - - 63 73 145 180 350 - -- -- 73 85 170 210 400 -- - 84 97 195 240 70-530 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 626—ELECTRIFIED TRUCK PARKING SPACES 626.2 Table 625.29(D)(2) Minimum Ventilation Required in Cubic Feet per Minute (cfm) for Each of the Total Number of Electric Vehicles That Can Be Charged at One Time Branch-Circuit Voltage Single Phase 3 Phase Branch- Circuit Ampere 240 V or 208 V or 480 V or 600 V or Rating 120 V 208 V 1201240 V 208Y/120 V 240 V 480Y/277 V 600Y1347 V 15 37 64 74 — — — 20 49 85 99 148 171 342 427 30 74 128 148 222 256 512 641 40 49 171 197 296 342 683 854 50 123 214 246 370 427 854 1066 60 148 256 296 444 512 1025 1281 100 246 427 493 740 854 1708 2135 150 — — — 1110 1281 2562 3203 2W — — — 1480 1708 3416 4270 250 — — 1850 2135 4270 5338 300 — -- — 2221 2.562 5125 6406 350 — — — 2591 2989 5979 7473 4I1t1 — — — 2961 3416 6832 8541 energized during the entire electric vehicle charging cycle, refrigerated units to a supply of electricity, and the instal- Electric vehicle supply equipment shall be marked in accor- lation of equipment and devices related to electrical instal- dance with 625.15. Electric vehicle supply equipment recep- lations within an electrified truck parking space, tacles rated at 125 volts,single phase, 15 and 20 amperes shall be marked in accordance with 625.15(C) and shall be 626.2 Definitions. switched, and the mechanical ventilation system shall be elec- Cable Management System. An apparatus designed to trically interlocked through the switch supply power to the control and organize unused lengths of cable or cord at receptacle, electrified truck arkin p g spaces. 625.30 Outdoor Sites. Outdoor sites shall include but not Cord Connector. A device that, by inserting it into a truck be limited to residential carports and driveways, curbside, Hanged surface inlet, establishes an electrical connection to open parking structures, parking lots, and commercial the truck for the purpose of providing power for the on- charging facilities. board electric loads and may provide a means for informa- tion exchange. This device is part of the truck coupler. (A) Location.The electric vehicle supply equipment shall be located to permit direct connection to the electric vehicle. Disconnecting Means, Parking Space. The necessary equipment usually consisting of a circuit breaker or switch (B) Height. Unless specifically listed for the purpose and and fuses, and their accessories, located near the point of location, the coupling means of electric vehicle supply entrance of supply conductors in an electrified truck park- equipment shall be stored or located at a height of not less ing space and intended to constitute the means of cutoff for than 600 mm (24 in.) and not more than 1.2 m (4 ft) above the supply to that truck. the parking surface. Electrified Truck Parking Space. A truck parking space that has been provided with an electrical system that allows truck operators to connect their vehicles while stopped and to use off-board power sources in order to operate on-board ARTICLE 626 systems such as air conditioning, heating, and appliances, Electrified Truck Parking Spaces without any engine idling. FPN: An electrified truck parking space also includes dedi- cated parking areas for heavy-duty trucks at travel plazas. I. General warehouses, shipper and consignee yards, depot facilities, 626.1 Scope. The provisions of this article cover the elec- and border crossings, It does not include areas such as the shoulders of highway ramps and access roads,camping and trical conductors and equipment external to the truck or recreational vehicle sites, residential and commercial park- transport refrigerated unit that connect trucks or transport ing areas used for automotive parking or other areas where 2009 Edition NATIONAL ELECPR1CAl,CODE 70-.531 626.3 ARTICLE 626--ELECTRIFIED TRUCK PARKING SPACES ac power is provided solely for the purpose of connecting FPN: For additional information, see NFPA 88A-2007, automotive and other light electrical loads, such as engine Standard for Parking Structures and NFPA 30A-2008, block heaters, and at private residences. Code for Fuel Dispensing Facilities and Repair Garages. Electrified Truck Parking Space Wiring Systems. All of 626.4 General Requirements. the electrical wiring, equipment, and appurtenances re- lated to electrical installations within an electrified truck (A) Not Covered. The provisions of this article shall not parking space, including the electrified parking space apply to that portion of other equipment in residential, com- supply equipment. mercial, or industrial facilities that require electric power for Overhead Gantry. A structure consisting of horizontal devices used to load and unload cargo and equipment,operate framework, supported by vertical columns spanning above conveyors and for other devices used on the site or truck. electrified truck parking spaces, that supports equipment, (B) Distribution System Voltages. Unless other voltages appliances, raceway, and other necessary components for are specified, the nominal ac system voltages of 120, the purpose of supplying electrical, HVAC, internet, com- 1201240,208Y1120,240, or 480Y/277 shall be used to sup- munications, and other services to the spaces. ply equipment covered by this article. Separable Power Supply Cable Assembly.A flexible cord or cable, including ungrounded, grounded, and equipment (C) Connection to Wiring System.The provisions of this grounding conductors, provided with a cord connector, an article shall apply to the electrified truck parking space attachment plug, and all other fittings, grommets, or de- supply equipment intended for connection to a wiring sys- vices installed for the purpose of delivering energy from the tem as defined in 626.4(B). source of electrical supply to the truck or TRU flanged surface inlet. II. Electrified Truck Parking Space Electrical Wiring Transport Refrigerated Unit (TRU). A trailer or con- Systems tainer, with integrated cooling or heating, or both, used for 626.10 Branch Circuits. Electrified truck parking space the purpose of maintaining the desired environment of single-phase branch circuits shall be derived from a temperature-sensitive goods or products. 208Y/120-volt, 3-phase, 4-wire system or a 1201240-volt, 'Duck. A motor vehicle designed for the transportation of single-phase, 3-wire system. goods, services, and equipment. Exception: A 120-volt distribution system shall be permit- Truck Coupler. A truck flanged surface inlet and mating ted to supply existing electrified truck parking spaces. cord connector. Truck Flanged Surface Inlet. The device(s) on the truck 626.11 Feeder and Service Load Calculations. into which the connector(s) is inserted to provide electric (A) Parking Space Load. The calculated load of a feeder energy and other services. This device is part of the truck or service shall be not less than the sum of the loads on the coupler. For the purposes of this article, the truck flanged branch circuits. Electrical service and feeders shall be cal- surface inlet is considered to be part of the truck and not part culated on the basis of not less than 11 kVA per electrified of the electrified truck parking space supply equipment. truck parking space. 626.3 Other Articles. Wherever the requirements of other (B) Demand Factors. Electrified truck parking space elec- articles of this Code and Article 626 differ,the requirements trical wiring system demand factors shall be based upon the of Article 626 shall apply. Unless electrified truck parking climatic temperature zone in which the equipment is in- space wiring systems are supported or arranged in such a stalled. The demand factors set forth in Table 626.11(B) manner that they cannot be used in or above locations classi- shall be the minimum allowable demand factors that shall tied in 511.3 or 514.3, or both, they shall comply with be permitted for calculating load for service and feeders. 626.3(A)and(B)in addition to the requirements of this article. No demand factor shall be allowed for any other load, ex- (A) Vehicle Repair and Storage Facilities. Electrified cept as provided in this article. truck parking space electrical wiring systems located at fa- FPN: The U.S. Department of Agriculture(USDA)has de- cilities for the repair or storage of self-propelled vehicles veloped a commonly used"Plant Hardiness Zone"map that that use volatile flammable liquids or flammable gases for is publicly available.The map provides guidance for deter- mining the Climatic Temperature Zone. Data indicate that fuel or power shall comply with Article 51I. the HVAC has the highest power requirement in cold cli- mates, with the heating demand representing the greatest (B) Motor Fuel Dispensing Stations. Electrified truck load, which in turn is dependent on outside temperature. In parking space electrical wiring systems located at or serving very warm climates,where no heating load is necessary,the motor fuel dispensing stations shall comply with Article 514. cooling load increases as the outdoor temperature rises. 70-532 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 626—ELECTRIFIED TRUCK PARKING SPACES 626.24 Table 626.11(B) Demand Factors For Services and Feeders III. Electrified Truck Parking Space Supply - Equipment Climatic Temperature Zone (USDA Hardiness Zone) Demand Factor 626.22 Wiring Methods and Materials. See Note (%) (A) Electrified Truck Parking Space Supply Equipment 70% Type.The electrified truck parking space supply equipment shall be provided in one of the following forms: 2a 67% (l) Pedestal 2b 62% (2) Overhead gantry (3) Raised concrete pad 3a 5917c (B) Mounting Height. Post, pedestal, and raised concrete 3b 57% pad types of electrified truck parking space supply equip- ment shall be not less than 600 mm (2 ft) aboveground or 4a 5S°%� above the point identified as the prevailing highest water 4b 51% level mark or an equivalent benchmark based on sea- sonal or storm-driven flooding from the authority having 5a 47% jurisdiction. 5b 43% (C) Access and Working Space. All electrified truck 6a 39 parking space supply equipment shall be accessible by an unobstructed entrance or passageway not less than 600 mm 6b 349 (2 ft) wide and not more than 2.0 m (6 ft 6 in.) high. 7a 29°7 (D) Disconnecting Means. A disconnecting switch or cir- cuit breaker shall be provided to disconnect one or more 7b 24% electrified truck parking space supply equipment sites from a remote location. The disconnecting means shall be pro- vided and installed in a readily accessible location and shall 8b 20% be capable of being locked in the open position. Portable means for adding a lock to the switch or circuit breaker 9a 20% shall not be permitted as the means required to be installed 9b 2017, at and remain with the equipment. l0a 2117 626.23 Overhead Gantry or Cable Management System. o (A) Cable Management. Electrified truck parking space lOb 2370 equipment provided from either overhead gantry or cable 11 24% management systems shall utilize a permanently attached power supply cable in electrified truck parking space sup- Note: The climatic temperature zones shown in Table 626.11(B)cor- ply equipment. Other cable types and assemblies listed as relate with [hose found on the "USDA Plant Hardiness Zone Map;' and the climatic temperature zone selected for use with the table shall being suitable for the purpose, including optional hybrid be determined through the use of this map based on the installation communications, signal, and optical fiber cables, shall be location. permitted. (B) Strain Relief. Means to prevent strain from being transmitted to the wiring terminals shall be provided. Per- manently attached power supply cable(s) shall be provided (C) Two or More Electrified Truck Parking Spaces. with a means to de-energize the cable conductors and Where the electrified truck parking space wiring system is power service delivery device upon exposure to strain that in a location that serves two or more electrified truck park- could result in either cable damage or separation from the ing spaces, the equipment for each space shall comply with power service delivery device and exposure of live parts. 626.11(A) and the calculated load shall be computed on the 626.24 Electrified ruck Parking Space Supply Equip- basis of each parking space. ment Connection Means. (D) Conductor Rating. Truck space branch-circuit conduc- (A) General. Each truck shall be supplied from electrified tors shall have an ampacity not less than the loads supplied. truck parking space supply equipment through suitable 2008 Edition NATIONAL ELECTRICAL,CODE 70-533 626.25 ARTICLE 626—ELECTRIFIED TRUCK PARKING SPACES extra-hard service cables or cords. Each connection to the (A) Rating(s). equipment shall be by a single separable power supply cable assembly. (1) Twenty-Ampere Power-Supply Cable Assembly. Equipment with a 20-ampere, 125-volt receptacle, in accor- (13) Receptacle. All receptacles shall be listed and of the dance with 626.24(B)(1), shall use a listed 20-ampere grounding type. Every truck parking space with electrical power-supply cable assembly. supply shall be equipped with (13)(1) and (13)(2). Exception: It shall be permitted to use a listed separable (1) Two single receptacles, each 2-pale, 3-wire grounding power-supply cable assembly, either hard service or extra- type, rated 20 amperes, 125 volts, and connected to an hard service and rated 15 amperes, 125 volts for connec- individual branch circuit. tion to an engine block heater for existing vehicles. FPN: For the nonlocking-type and grounding-type 20- (2) Thirty-Ampere Power-Supply Cable Assembly. ampere receptacle configuration, see ANSI/NEMA WD6- Equipment with a 30-ampere, 208Y/120-volt or 1251250- 2002, Standard for Dimensions of Attachment Plugs and volt receptacle, in accordance with 626.24(B)(2), shall use Receptacles. Figure 5-20. a listed 30-ampere main power-supply cable assembly. (2) One single receptacle, 3-pale, 4-wire grounding-type, single-phase rated either 30 amperes 208YI120 volts or (B) Power-Supply Cord. 1251250 volts. The 1251250-volt receptacle shall be permitted to be used on a 208Y/120-volt, single-phase (1) Conductors. The cord shall be a listed type with three or four conductors, for single-phase connection, one con- circuit. ductor of which shall be identified in accordance with FPN: For various configurations of 30-ampere pin and 400.23. sleeve receptacles, see ANSI/UL1686, Standard for Pin and Sleeve Configurations, Figure C2.9 or Part C3. Exception: It shall be permitted to use a separate listed three-conductor separable power-supply cable assembly, Exception: Where electrified truck parking space supply one conductor of which shall be identified in accordance equipment provides the air-conditioning and comfort cool- with 400.23 and rated 15 amperes, 125 volts for connection ing function without requiring a direct electrical connec- to an engine block heater for existing vehicles, tion at the truck, only the two receptacles identified in 626.24(B)(1) shall be required. (2) Cord. Extra-hard usage flexible cords and cables rated not less than 90°C (194°F), 600 volts; listed for both wet (C) Disconnecting Means, Parking Space.The electrified locations and sunlight resistance; and having an outer truck parking space supply equipment shall be provided with a jacket rated to be resistant to temperature extremes, oil, switch or circuit breaker for disconnecting the power supply to gasoline, ozone, abrasion, acids, and chemicals shall be the electrified truck parking space. A disconnecting means permitted where flexibility is necessary between the electri- shall be provided and installed in a readily accessible location fied truck parking space supply equipment, the panel board and shall be capable of being locked in the open position. and flanged surface inlet(s) on the truck. Portable means for adding a lock to the switch or circuit Exception: Cards for the separable power supply cable as- breaker shall not be permitted as the means required to be sembly for 15- and 20-ampere connections shall be permit- installed at and remain with the equipment, ted to be a hard service type. (D) Ground-Fault Circuit-Interrupter Protection for (3) Cord Overall Length. The exposed cord length shall Personnel. The electrified truck parking space equipment be measured from the face of the attachment plug to the shall be designed and constructed such that all receptacle point of entrance to the truck or the face of the flanged outlets in 626.24 are provided with ground-fault circuit- surface inlet or to the point where the cord enters the truck. interrupter protection for personnel. The overall length of the cable shall not exceed 7.5 m (25 ft) unless equipped with a cable management system 626.25 Separable Power-Supply Cable Assembly. A that is listed as suitable for the purpose, separable power-supply cable assembly, consisting of a (4) Attachment Plug. The attachment plug(s) shall be power-supply cord, a cord connector, and an attachment listed, by itself or as part of a cord set, for the purpose and plug intended for connection with a truck flanged surface shall be molded to or installed on the flexible cord so that it inlet, shall be of a listed type. The power-supply cable is secured tightly to the cord at the point where the cord assembly or assemblies shall be identified and be one of the enters the attachment plug. if a right-angle cap is used, the types and ratings specified in 626.25(A) and (B). Cords configuration shall be oriented so that the grounding mem- with adapters and pigtail ends, extension cords, and similar ber is farthest from the cord. Where a flexible cord is pro- items shall not be used. vided, the attachment plug shall comply with 250.138(A). 70-531 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 626—ELECTRIFIED TRUCK PARKING SPACES 626.31 (a) Connection to a 20-Ampere Receptacle. A separable intended to be interconnected to a vehicle and also serve as power-supply cable assembly for connection to a truck an optional standby system or an electric power production flanged surface inlet, rated at 20 amperes, shall have a source or provide for bi-directional power feed shall be nonlocking-type attachment plug that shall be 2-pole, listed as suitable for that purpose.When used as an optional 3-wire grounding type rated 20 amperes, 125 volts and standby system,the requirements of Article 702 shall apply, intended for use with the 20-ampere, 125-volt receptacle, and when used as an electric power production source, the Exception: A separable power-supphy cable assembh; rated requirements of Article 705 shall apply. 15 amperes, provided for the confection of an engine block heater, only, shall have an attachment plug that shall be IV. Transport Refrigerated Units (TRUs) 2-pole, 3-wire grounding tlpe rated 15 amperes, 125 volts. 626.30 Transport Refrigerated Units. Electrified truck FPN: For nonlocking- and grounding-type 15- or 20- parking spaces intended to supply transport refrigerated ampere plug and receptacle configurations, see ANSI/ units (TRUs) shall include an individual branch circuit and NEMA WD6-2002,Standard for Dimensions nfAttac•hrnew Plugs and Receptacles,Figure 5-15 or 5-20. receptacle for operation of the refrigeration/heating units. The receptacle associated with the TRUs shall be provided (b) Connection to a 30-Ampere Receptacle. A separable in addition to the receptacles required in 626.24(B). power-supply cable assembly for connection to a truck flanged surface inlet,rated at 30 amperes,shall have an attach- (A) Branch Circuits. TRU spaces shall be supplied from meat plug that shall be 3-pole, 4-wire grounding type rated 208-volt, 3-phase or 4$0-volt, 3-phase branch circuits and 30-amperes, 208Y1120 volts or 1251250 volts, and intended With an equipment grounding conductor in accordance with for use with the receptacle in accordance with 626.24(B)(2). 250.118. The 1251250-volt attachment plug shall be permitted to be (B) Electrified Truck Parking Space Supply Equip- used on a 208Y/120-volt, single-phase circuit, ment. The electrified truck parking space supply equip- FPN: For various configurations of 30-ampere pin and ment, or portion thereof, providing electric power for the sleeve plugs, see ANSI/UL1686, Standard for Pin and operation of TRUs shall be independent of the loads in Part Sleeve Configurations, Figure C2.10 or Part C3. III of Article 626. (5) Cord Connector. The cord connector for a separable power-supply cable assembly, as specified in 626.25(A)(1), 626.31 Disconnecting Means and Receptacles. shall be a 2-pole, 3-wire grounding type rated 20 amperes, (A) Disconnecting Means. Disconnecting means shall be 125 volts.The cord connector for a separable power-supply provided to isolate each refrigerated unit from its supply cable assembly, as specified in 626.25(A)(2), shall be a connection, A disconnecting means shall be provided and 3-pole, 4-wire grounding type rated 30 amperes, 208Y1120 installed in a readily accessible location and shall be ca- volts or 1251250 volts. The 1251250-volt cord connector pable of being locked in the open position. Portable means shall be permitted to be used on a 208Y1120-volt, single- for adding a lock to the switch or circuit breaker shall not phase circuit. be permitted as the means required to be installed at and Exception: The cord connector for a separable power sup- remain with the equipment. phy cable assetbly, rated 15 amperes,provided for the con- (B) Location. The disconnecting means shall be readily nection of an engine block heater for existing vehicles, accessible, located not more than 750 mm (30 in.) from the shall have an attac•hntent plug that shall be 2-pale, 3-wire receptacle it controls, and located in the supply circuit grounding tvpe rated 15 amperes, 125 volts. ahead of the receptacle. Circuit breakers or switches lo- FPN: For various configurations of 30-ampere cord con- cated in power outlets complying with this section shall be nectors, see ANSIML1686 Standard for Pin and Sleeve permitted as the disconnecting means. Configurations, Figure C2.9 or Pan C3. (C) Receptacles. All receptacles shall be listed and of the 626.26 Loss of Primary Power. Means shall be provided grounding type.Every electrified truck parking space intended such that,upon loss of voltage from the utility or other electric to provide an electrical supply for transport refrigerated units supply system(s),energy cannot be back-fed through the truck shall be equipped with one or both of the following: and the truck supply equipment to the electrified truck parking (1) A 30-ampere,480-volt,3-phase, 3-pole,4-wire receptacle space wiring system unless permitted by 626.27. (2) A 60-ampere,208-volt,3-phase, 3-pole,4-wire receptacle FPN: Complete details of the 30-ampere pin and sleeve 626.27 Interactive Systems. Electrified [ruck parking receptacle configuration for refrigerated containers (trans- space supply equipment and other parts of a system, either port refrigerated units) can be found in ANSIIUL1686, on-board or of board the vehicle, that are identified for and Standard•for Pin and Sleeve Configurations, Figure C2.11. 2008 Edition NATIONAL ELECTRICAL.CODE 70-535 626.32 ARTICLE 630-ELECTRIC WELDERS For various configurations of 60-ampere pin and sleeve re- ceptacles, see ANSI/UL1686. ARTICLE 1130 626.32 Separable Power Supply Cable Assembly. A Electric Welders separable power supply cable assembly, consisting of a cord with an attachment plug and cord connector, shall be 1. General one of the types and ratings specified in 626.32(A), (B), 630.1 Scope. This article covers apparatus for electric arc and (C). Cords with adapters and pigtail ends, extension welding, resistance welding, plasma cutting, and other cords, and similar items shall not be used. similar welding and cutting process equipment that is con- (A) Rating(s). The power supply cable assembly shall be nected to an electrical supply system. listed and be rated in accordance with (1) or (2). (1) 30 ampere, 480-volt, 3-phase 11. Are Welders (2) 60 ampere, 208-volt, 3-phase 630.11 Ampacity of Supply Conductors.The ampacity of conductors for arc welders shall be in accordance with (B) Cord Assemblies.The cord shall be a listed type with 630.11(A) and (B). four conductors, for 3-phase connection,one of which shall be identified in accordance with 400.23 for use as the (A) Individual Welders. The ampacity of the supply con- equipment grounding conductor. Extra-hard usage cables ductors shall be not less than the 11eff value on the rating rated not less than 90°C 094°F), 600 volts, listed for both plate.Alternatively, if the it,ff is not given, the ampacity of wet locations and sunlight resistance, and having an outer the supply conductors shall not be less than the current jacket rated to be resistant to temperature extremes, oil, value determined by multiplying the rated primary current gasoline, ozone, abrasion, acids, and chemicals, shall be in amperes given on the welder rating plate by the factor permitted where flexibility is necessary between the electri- shown in Table 630.11(A) based on the duty cycle of the fied truck parking space supply equipment and the inlet(s) welder. on the TRU. Table 630.11(A) Duty Cycle Multiplication Factors for Arc Welders (C) Attachment Plug(s) and Cord Connector(s). Where a flexible cord is provided with an attachment plug and Multiplier for Are Welders cord connector, they shall comply with 250.138(A). The attachment plug(s) and cord connector(s) shall be listed, by Generator Motor Duty Cycle Generator Generator itself or as part of the power-supply cable assembly,for the purpose and shall be molded to or installed on the flexible 100 1.00 1.00 cord so that it is secured tightly to the cord at the point 90 0.95 0.96 where the cord enters the attachment plug or cord connec- 80 0.89 0.91 70 0.84 0.86 tor. If a right-angle cap is used, the configuration shall be 60 0.78 0.81 oriented so that the grounding member is farthest from the 50 0.71 0.75 cord. An attachment plug and cord connector for the con- 40 0.63 0.69 nection of a truck or trailer shall be rated in accordance 30 0.55 0.62 20 or less 0.45 0.55 with (1) or (2) as follows: (1) 30-ampere, 480-volt, 3-phase, 3-pole, 4-wire and in- (B) Group of Welders. Minimum conductor ampacity tended for use with a 30-ampere 480-volt, 3-phase, shall be based on the individual currents determined in 3-pole, 4-wire receptacles and inlets, respectively, or 630.1](A) as the sum of 100 percent of the two largest (2) 60-ampere, 208-volt, 3-phase, 3-pole, 4-wire and in- welders, plus 85 percent of the third largest welder, plus tended for use with a 60-ampere, 208-volt, 3-phase, 70 percent of the fourth largest welder, plus 60 percent of 3-pole, 4-wire receptacles and inlets, respectively. all remaining welders. FPN: Complete details of the 30-ampere pin and sleeve Exception: Percentage values lower than those given in attachment plug and cord connector configurations for re- 630.11(B) shall be permitted in Cases where the work is frigerated containers (transport refrigerated units) can be such that a high-operating duty cycle for individual welders found in ANSI/UL1686,Standard for Pin and Sleeve Con- is impassible. figurations, Figures 02.12 and C2.1 t.For various configu- rations of 60-ampere pin and sleeve attachment plugs and FPN: Duty cycle considers welder loading based on the use cord connectors, see ANSVUL.1686. to be made of each welder and the number of welders supplied 70-536 NA'r1ONAL ELECTRICAL CODE 2008 Edition ARTICLE 630—ELECTRIC WELDERS 630.31 by the conductors that will be in use at the same time. The (7) Rated secondary current load value used for each welder considers both the magnitude and the duration of the load while the welder is in use. (K) Basis of rating, such as the duty cycle 630.12 Overcurrent Protection. Overcurrent protection 630.15 Grounding of Welder Secondary Circuit. The for are welders shall be as provided in 630.12(A) and (B)' secondary circuit conductors of an arc welder,consisting of Where the values as determined by this section do not cor- the electrode conductor and the work conductor, shall not respond to the standard ampere ratings provided in 240.6 or be considered as premises wiring for the purpose of apply- where the rating or setting specified results in unnecessary ing Article 250. opening of the overcurrent device, the next higher standard FPN: Connecting welder secondary circuits to grounded rating or setting shall be permitted, objects can create parallel paths and can cause objection- (A) For Welders. Each welder shall have overcurrent pro- able current over equipment grounding conductors. tection rated or set at not more than 200 percent of Itmax Alternatively, if the is not given, the overcurrent pro- III. Resistance Welders tection shall be rated or set at not more than 200 percent of 630.31 Ampacity of Supply Conductors. The ampacity the rated primary current of the welder. of the supply conductors for resistance welders necessary to An overcurrent device shall not be required for a welder limit the voltage drop to a value permissible for the satis- that has supply conductors protected by an overcurrent de- factory performance of the welder is usually greater than vice rated or set at not more than 200 percent of It,,,ax or at that required to prevent overheating as covered in the rated primary current of the welder. 630.31(A) and (B), If the supply conductors for a welder are protected by an overcurrent device rated or set at not more than 200 per- (A) Individual Welders, The rated ampacity for conduc- cent of or at the rated primary current of the welder, a tors for individual welders shall comply with the following: separate overcurrent device shall not be required. (1) The ampacity of the supply conductors for a welder (B) For Conductors. Conductors that supply one or more that may be operated at different times at different val- welders shall be protected by an overcurrent device rated or ues of primary current or duty cycle shall not be less set at not more than 200 percent of the conductor ampacity. than 70 percent of the rated primary current for seam and automatically fed welders, and 50 percent of the FPN: 11-aX is the maximum value of the rated supply cur- rated primary current for manually operated nonauto- rent at maximum rated output. l,,„ is the maximum value matic welders. of the effective supply current, calculated from the rated supply current(1,),the corresponding duty cycle (duty fac- (2) The ampacity of the supply conductors for a welder tor) (X), and the supply current at no-load (1„) by the fol- wired for a specific operation for which the actual pri- lowing formula: mary current and duty cycle are known and remain unchanged shall not be less than the product of the 1;X+1;;{1-X) actual primary current and the multiplier specified in Table 630.31(A)(2) for the duty cycle at which the 630.13 Disconnecting Means. A disconnecting means welder will be operated. shall be provided in the supply circuit for each arc welder that is not equipped with a disconnect mounted as an inte- gral part of the welder. supply two or more welders shall not be less than the sum The disconnecting means shall be a switch or circuit Table 630.31(A)(2) Duty Cycle Multiplication Factors for breaker, and its rating shall be not less than that necessary Resistance Welders to accommodate overcurrent protection as specified under 630.12• Duty Cycle °!o) Multiplier 630.14 Marking. A rating plate shall be provided for arc ( - welders giving the following information: 50 0.71 (1) Name of manufacturer 40 0.63 30 0.55 (2) Frequency 25 0,50 (3) Number of phases 20 0.45 (4) Primary voltage 15 0.3 10 0.32 2 (5) hmax and 11.,r, or rated primary current 7.5 0.27 (6) Maximum open-circuit voltage 5 or less 0,22 2008 Edition NATIONAL ELECTRICAL CODE 70-537 630.32 ARTICLE 640—AUDIO SIGNAL PROCESSING,AMPLIFICATION,AND REPRODUCTION EQUIPMENT of the value obtained in accordance with 630.31(A) for the (6) Short-circuit secondary current at maximum secondary largest welder supplied and 60 percent of the values ob- voltage tained for all the other welders supplied. (7) Specified throat and gap setting FPN: Explanation of Terms (1) The rated primary current is the rated kilovolt-amperes IV. Welding Cable (kVA) multiplied by 1000 and divided by the rated primary voltage, using values given on the nameplate. 630.41 Conductors. Insulation of conductors intended for (2) The actual primary current is the current drawn from use in the secondary circuit of electric welders shall be the supply circuit during each welder operation at the flame retardant. particular heat lap and control setting used. (3) The duty cycle is the percentage of the time during which the welder is loaded.For instance,a spot welder 630.42 Installation. Cables shall be permitted to be in- supplied by a 60-Hz system (216,000 cycles per hour) stalled in a dedicated cable tray as provided in 630.42(A), and making four hundred 15-cycle welds per hour (B), and (C). would have a duty cycle of 2.8 percent(400 multiplied by 15,divided by 216,000,multiplied by 100).A seam (A) Cable Support. The cable tray shall provide support welder operating 2 cycles "on" and 2 cycles "off" at not greater than 150-mm (6-in.) intervals. would have a duty cycle of 50 percent. 630.32 Overcurrent Protection. Overcurrent protection (B) Spread of Fire and Products of Combustion. The for resistance welders shall be as provided in 630.32(A) installation shall comply with 300.21. and (B). Where the values as determined by this section do (C) Signs. A permanent sign shall be attached to the cable not correspond with the standard ampere ratings provided tray at intervals not greater than 6.0 m (20 ft). The sign in 240.6 or where the rating or setting specified results in shall read as follows: unnecessary opening of the overcurrent device, a higher rating or setting that does not exceed the next higher stan- CABLE TRAY FOR WELDING CABLES ONLY dard ampere rating shall be permitted. (A) For Welders. Each welder shall have an overcurrent device rated or set at not more than 300 percent of the rated primary current of the welder. If the supply conductors for ARTICLE 640 a welder are protected by an overcurrent device rated or set Audio Signal Processing,Amplification, at not more than 200 percent of the rated primary current of and Reproduction Equipment the welder,a separate overcurrent device shall not be required. (B) For Conductors. Conductors that supply one or more h General welders shall be protected by an overcurrent device rated or set at not more than 300 percent of the conductor rating. 640.1 Scope. This article covers equipment and wiring for audio signal generation, recording, processing, amplifica- 630.33 Disconnecting Means. A switch or circuit breaker tion and reproduction; distribution of sound; public ad- shall be provided by which each resistance welder and its dress; speech input systems;temporary audio system instal- control equipment can be disconnected from the supply lations; and electronic organs or other electronic musical circuit.The ampere rating of this disconnecting means shall instruments. This also includes audio systems subject to not be less than the supply conductor ampacity determined Article 517, Part VI, and Articles 518, 520, 525, and 530, in accordance with 630.31. The supply circuit switch shall FPN No. 1: Examples of permanently installed distributed be permitted as the welder disconnecting means where the audio system locations include, but are not limited to, res- circuit supplies only one welder. taurant, hotel, business office, commercial and retail sales environments, churches, and schools. Both portable and 630.34 Marking. A nameplate shall be provided for each Permanently installed equipment locations include, but are not limited to, residences, auditoriums, theaters, stadiums, resistance welder, giving the following information: and movie and television studios. Temporary installations (1) Name of manufacturer include,but are not limited to, auditoriums,theaters,stadi- (2) Frequency ums (which use both temporary and permanently installed systems), and outdoor events such as fairs, festivals, cir- (3) Primary voltage cuses, public events, and Concerts. (4) Rated kilovolt-amperes (kVA) at 50 percent duty cycle FPN No. 2: Fire and burglary alarm signaling devices are (5) Maximum and minimum open-circuit secondary voltage specifically not encompassed by this article. 70-538 NATIONAL ELECMICAL CODE 2008 Edition ARTICLE 640—AUDIO SIGNAL PROCESSING.AMPLIFICATION,AND REPRODUCTION EQUIPMENT 640,3 640.2 Definitions. For purposes of this article, the follow- under specified test conditions. This may exceed the manu- ing definitions apply. facturer's rated output power for the same amplifier. Abandoned Audio Distribution Cable. Installed audio Mixer. Equipment used to combine and level match a mul- distribution cable that is not terminated at equipment and tiplicity of electronic signals, such as from microphones, not identified for future use with a tag. electronic instruments, and recorded audio. Audio Amplifier or Pre-Amplifier. Electronic equipment Mixer—Amplifier. Equipment that combines the functions that increases the current or voltage, or both, potential of an of a mixer and amplifier within a single enclosure. audio signal intended for use by another piece of audio equipment. Amplifier is the term used to denote an audio Portable Equipment. Equipment fed with portable cords amplifier within this article. or cables intended to be moved From one place to another. Audio Autotransformer. A transformer with a single Powered Loudspeaker. Equipment that consists of a loud- winding and multiple taps intended for use with an ampli- speaker and amplifier within the same enclosure. Other sig- fier loudspeaker signal output. nal processing may also be included. Audio Signal Processing Equipment. Electrically oper- Rated Load Impedance. The amplifier manufacturer's ated equipment that produces,processes, or both, electronic stated or marked speaker impedance into which an ampli- signals that, when appropriately amplified and reproduced fier will deliver its rated output power, 252, 452, and 8S2 are by a loudspeaker, produce an acoustic signal within the typical ratings. range of normal human hearing (typically 20-20 kHz). Rated Output Power. The amplifier manufacturer's stated Within this article, the terms equipment and audio equip- or marked output power capability into its rated load. [[tent are assumed to be equivalent to audio signal process- ing equipment, Rated Output Voltage. For audio amplifiers of the constant-voltage type, the nominal output voltage when the FPN: This equipment includes, but is not limited to, loud- amplifier is delivering full rated power. Rated output volt- speakers; headphones; pre-amplifiers; microphones and age is used for determining approximate acoustic output in their power supplies; mixers; MIDI (musical instrument distributed speaker systems that typically employ imped- digital interface) equipment or other digital control sys- tems; equalizers, compressors, and other audio signal pro- ante matching transformers. Typical ratings are 25 volts, cessing equipment; and audio media recording and play- 70.7 volts, and 100 volts. back equipment, including turntables, tape decks and disk players (audio and multimedia), synthesizers, tone genera- Technical Power System.An electrical distribution system tors, and electronic organs. Electronic organs and synthe- with grounding in accordance with 250.146(D), where the sizers may have integral or separate amplification and loud- equipment grounding conductor is isolated from the pre- speakers. With the exception of amplifier outputs, virtually raises grounded conductor except at a single grounded ter- all such equipment is used to process signals(utilizing ana- mination point within a branch-circuit anelboard, at the log or digital techniques) that have nonhazardous levels of p voltage or current potential. originating (main breaker) branch-circuit panelboard, or at Audio System. Within this article, the totality of all equip- the premises grounding electrode. ment and interconnecting wiring used to fabricate a fully Temporary Equipment. Portable wiring and equipment functional audio signal processing, amplification, and re- intended for use with events of a transient or temporary production system. nature where all equipment is presumed to be removed at the conclusion of the event. Audio Transformer. A transformer with two or more elec- trically isolated windings and multiple taps intended for use 640.3 Locations and Other Articles.Circuits and equipment with an amplifier loudspeaker signal output. shall comply with 640.3(A) through (L), as applicable. Equipment Rack. A framework for the support, enclosure, (A) Spread of Fire or Products of Combustion. Section or both, of equipment; may be portable or stationary. See 300.21 shall apply. ANSI/EIA/3IO-D-1992, Cabinets, Racks, Panels and Asso- ciated Equipment. (B) Ducts, Plenums, and Other Air-Handling Spaces. Loudspeaker.Equipment that converts an ac electric signal See 300.22 for circuits and equipment installed in ducts or into an acoustic signal.The term speaker is commonly used plenums or other space used for environmental air. to mean loudspeaker. FPN: NFPA 90A-2002,Standard for the Installation of Air Conditioning and Ventilation Spstetns, Section 4.3.10 2.6.5, Maximum Output Power. The maximum output power permits loudspeakers, loudspeaker assemblies,and their ac- delivered by an amplifier into its rated load as determined cessories listed in accordance with UL 2043-1996,Fire Test 2008 Edition NATIONAL ELECTRICAL CODE 70_...539 640.4 ARTICLE 640—AUDIO SIGNAL PROCESSING,AMPLIFICATION,AND REPRODUCTION EQUIPMENT for Heat and Visible Smoke Release for Discrete Products physical damage, such as might result in fire, shock, or and Their Accessories Installed in Air-Handling Spaces, to personal hazard. be installed in other spaces used for environmental air(ceil- ing cavity plenums). 640.5 Access to Electrical Equipment Behind Panels (C) Cable Trays. Cable trays shall be used in accordance Designed to Allow Access. Access to equipment shall not with Article 392. be denied by an accumulation of wires and cables that FPN: See 725.154(C) for the use of Class 2, Class 3, and prevents removal of panels, including suspended ceiling Type PLTC cable in cable trays. panels. (D) Hazardous(Classified)Locations.Equipment used in 640.6 Mechanical Execution of Work. hazardous (classified) locations shall comply with the ap- plicable requirements of Chapter 5. (A) meat and Workmanlike Manner. Audio signal pm- cessing, amplification, and reproduction equipment, cables, (E) Assembly Occupancies. Equipment used in assembly and circuits shall be installed in a neat workmanlike manner. occupancies shall comply with Article 518. (B) Installation of Audio Distribution Cables.Cables in- (F) Theaters, Audience Areas of Motion Picture and stalled exposed on the surface of ceilings and sidewalls Television Studios, and Similar Locations. Equipment shall be supported in such a manner that the audio distribu- used in theaters, audience areas of motion picture and tele- lion cables will not be damaged by normal building use. vision studios, and similar locations shall comply with Ar- Such cables shall be Secured by straps, staples, cable ties, ticle 520. hangers, or similar fittings designed and installed so as not to damage the cable. The installation shall conform to (G) Carnivals, Circuses, Fairs, and Similar Events. 300.4 and 300.11(A). Equipment used in carnivals, circuses, fairs, and similar • events shall comply with Article 525. (C) Abandoned Audio Distribution Cables. The acces- sible portion of abandoned audio distribution cables shall (H) Motion Picture and Television Studios. Equipment be removed. used in motion picture and television studios shall comply with Article 530. (D) Installed Audio Distribution Cable Identified for Future Use. (I) Swimming Pools, Fountains, and Similar Locations. Audio equipment used in or near swimming pools, foun- (I) Cables identified for future use shall be marked with a tains, and similar locations shall comply with Article 680. tag of sufficient durability to withstand the environment involved. (J) Combination Systems. Where the authority having ju- (2) Cable tags shall have the following information: risdiction permits audio systems for paging or music, or both, to be combined with fire alarm systems, the wiring (t) Date cable was identified for future use shall comply with Article 760. (2) Date of intended use FPN: For installation requirements for such combination (3) Information related to the intended future use of cable systems, refer to NFPA 720-2007, National Fire Alarm. • Code, and NFPA 1010"-2006, Life Safety Code°. 640.7 Grounding. (K) Antennas.Equipment used in audio systems that con- (A) General. Wireways and auxiliary gutters shall be con- tain an audio or video tuner and an antenna input shall neeted to an equipment grounding conductor(s), to all comply with Article 810. Wiring other than antenna wiring equipment bonding jumper, or to the grounded conductor that connects such equipment to other audio equipment where, permitted or required by 250.92(B)(1) or 250.142. shall comply with this article. Where the wireway or auxiliary gutter does not contain power-supply wires, the equipment grounding conductor (L) Generators. Generators shall be installed in accor- shall not be required to be larger than 14 AWG copper or its dance with 445.10 through 445.12, 445.14 through 445.16, equivalent. Where the wireway or auxiliary gutter contains and 445.18. Grounding of portable and vehicle-mounted power-supply wires, the equipment grounding conductor generators shall be in accordance with 250.34. shall not be smaller than specified in 250.122. 640.4 Protection of Electrical Equipment. Amplifiers, (B) Separately Derived Systems with 60 Volts to loudspeakers, and other equipment shall be so located or Ground. Grounding of separately derived systems with 60 protected as to guard against environmental exposure or volts to ground shall be in accordance with 647.6. 70-540 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 640—AUDIO SIGNAL PROCESSING,AMPLIFICATION,AND REPRODUCTION EQUIPMENT 640.10 (C) Isolated Ground Receptacles. Isolated grounding- Lion shall be provided and shall be permitted to be inherent type receptacles shall be permitted as described in in the amplifier. 250.146(D), and for the implementation of other technical Audio amplifier output circuits wired using Class 1 wir- power systems in compliance with Article 250. For sepa- ing methods shall be considered equivalent to Class 1 cir- rately derived systems with 60 volts to ground, the branch- cuits and shall be installed in accordance with 725.46, circuit equipment grounding conductor shall be terminated where applicable. as required in 647.6(B). Audio amplifier output circuits wired using Class 2 or Class 3 wiring methods shall be considered equivalent to FPN: See 40 ratio for grounding type receptacles and re- Class 2 or Class 3 circuits, respectively. The shall use quired identification. P Y• Y conductors insulated at not less than the requirements of 640.8 Grouping of Conductors. Insulated conductors of 725.179 and shall be installed in accordance with 725.133 different systems grouped or bundled so as to be in close and 725.154. physical contact with each other in the same raceway or FPN No, 1: ANSIIUL 1711-1994,Amplifiers for Fire Pro- other enclosure, or in portable cords or cables,shall comply tective Signaling Systems, contains requirements for the with 300.3(C)(1). listing of amplifiers used for fire alarm systems in compli- ance with NFPA 72-2007, National Fire Alarm Code. 640.9 Wiring Methods. FPN No.2: Examples of requirements for listing amplifiers used in residential, commercial, and professional use are (A) Wiring to and Between Audio Equipment, found in ANSIIUL 813-1996, Commercial Audio Equip- ment; ANSIIUL 1419-1997, Professional Video and Audia (1) Power Wiring. Wiring and equipment from source of Equipment; ANSUUL 1492-1996, Audio-Video Products power to and between devices connected to the premises and Accessories, and ANSIIUL 6500-1996, AudiolVideo wiring systems shall comply with the requirements of and Musical Instrunient Apparatus for Nousehotd, Com- Chapters 1 through 4, except as modified by this article. menial, and Similar Use. (D) Use of Audio Transformers and Autotransformers. (2) Separately Derived Power Systems. Separately de- Audio transformers and autotransfarmers shall be used only rived systems shall comply with the applicable articles of For audio signals in a manner so as not to exceed the manu- this Code, except as modified by this article. Separately facturer's stated input or output voltage, impedance, or derived systems with 60 volts to ground shall be permit- power limitations. The input or output wires of an audio Article 647.for use in audio system installations as specified in transformer or autotransformer shall be allowed to connect Ar directly to the amplifier or loudspeaker terminals. No elec- (3) Other Wiring. All wiring not connected to the pre- trical terminal or lead shall be required to be grounded or mises wiring system or to a wiring system separately de- bonded. rived from the premises wiring system shall comply with 640.10 Audio Systems Near Bodies of Water. Audios s Article 725. Y - tems near bodies of water, either natural or artificial, shall (B) Auxiliary Power Supply Wiring. Equipment that has be subject to the restrictions specified in 640.10(A)and(B). a separate input for an auxiliary power supply shall be Exception: This section does not include audio systems in- wired in compliance with Article 725. Battery installation tended for use on boats, Yachts, or other forms of land or shall be in accordance with Article 480. water transportation used near bodies of water, whether or FPN No. l: This section does not apply to the use of un- not supplied by branch-circuit power. interruptible power supply (UPS) equipment, or other FPN: See 680.27(A) for installation of underwater audio sources of supply, that are intended to act as a direct re- equipment. placement for the primary circuit power source and are connected to the primary circuit input. (A) Equipment Supplied by Branch-Circuit Power. Au- FPN No. 2: Refer to NFPA 72-2007, National Fire Alann dio system equipment supplied by branch-circuit power Code, where equipment is used for a fire alarm system. shall not be placed laterally within 1.5 m (5 ft)of the inside wall of a pool, spa, hot tub, or fountain, or within 1.5 m (C) Output Wiring and Listing of Amplifiers.Amplifiers (5 ft) of the prevailing or tidal high water mark.The equip- ment shall be provided with branch-circuit power protected permitted to employ Class 1, Class 2, or Class 3 wiring by a ground-fault circuit interrupter where required by where the amplifier is listed and marked for use with the other articles. specific class of wiring method. Such listing shall ensure the energy output is equivalent to the shock and fire risk of (B) Equipment Not Supplied by Branch-Circuit Power. the same class as stated in Article 725. Overcurrent protec- Audio system equipment powered by a listed Class 2 power 2008 Edition NATIONAL ELECTRICAL CODE 70-541 646.21 ARTICLE 640—AUDIO SIGNAL PROCESSING,AMPLIFICATION,AND REPRODUCTION EQUIPMENT supply or by the output of an amplifier listed as permitting closure. Flexible cords and cables shall not be subjected to the use of Class 2 wiring shall be restricted in placement physical manipulation or abuse while the rack is in use. only by the manufacturer's recommendations. FPN: Placement of the power supply or amplifier, if sup- 640.22 Wiring of Equipment Racks and Enclosures. plied by branch-circuit power, is still subject to 640.10(A). Metal equipment racks and enclosures shall be grounded. Bonding shall not be required if the rack is connected to a technical power ground. II. Permanent Audio System Installations Equipment racks shall be wired in a neat and workman- 640.21 Use of Flexible Cords and Cables. like manner. Wires, cables, structural components, or other equipment shall not be placed in such a manner as to prevent (A) Between Equipment and Branch-Circuit Power. reasonable access to equipment power switches and resettable Power supply cords for audio equipment shall be suitable or replaceable circuit overcurrent protection devices. for the use and shall be permitted to be used where the Supply cords or cables, if used, shall terminate within interchange, maintenance, or repair of such equipment is the equipment rack enclosure in an identified connector facilitated through the use of a power-supply cord. assembly.The supply cords or cable (and connector assem- bly if used) shall have sufficient ampacity to carry the total (B) Between Loudspeakers and Amplifiers or Between load connected to the equipment rack and shall be protected Loudspeakers. Cables used to connect loudspeakers to by overcurrent devices. each other or to an amplifier shall comply with Article 725. Other listed cable types and assemblies, including optional 640.23 Conduit or Tubing, hybrid communications, signal, and optical fiber cables, shall be permitted. (A) Number of Conductors. The number of conductors permitted in a single conduit or tubing shall not exceed the (C) Between Equipment. Cables used for the distribution Percentage fill specified in Table 1, Chapter 9. of audio signals between equipment shall comply with Ar- (g) Nonmetallic Conduit or Tubing and Insulating ticle 725.Other listed cable types and assemblies, including Bushings. The use of nonmetallic conduit or tubing and optional hybrid communications, signal, and optical fiber insulating bushings shall be permitted where a technical cables,shall be permitted.Other cable types and assemblies power system is employed and shall comply with appli- specified by the equipment manufacturer as acceptable for cable articles. the use shall be permitted in accordance with 110.3(B). 640.24 Wireways, Gutters, and Auxiliary Gutters. The (D) Between Equipment and Power Supplies Other use of metallic and nonmetallic wireways,gutters, and aux- Than Branch-Circuit Power. The following power sup- iliary gutters shall be permitted for use with audio signal plies, other than branch-circuit power supplies, shall be in- conductors and shall comply with applicable articles with stalled and wired between equipment in accordance with the requirements of this Code for the voltage and power respect to permitted locations, construction, and fill. delivered: 640.25 Loudspeaker Installation in Fire Resistance- (1) Storage batteries Rated Partitions, Walls, and Ceilings. Loudspeakers in- (2) Transformers stalled in a fire resistance-rated partition, wall, or ceiling (3) Transformer rectifiers shall be listed for that purpose or installed in an enclosure (4) Other ac or do power supplies or recess that maintains the fire resistance rating. FPN: For some equipment, these sources such as in items FPN: Fire-rated construction is the fire-resistive classifica- (1)and(2)serve as the only source of power.These could, tion used in building codes.One method of determining fire in turn,be supplied with intermittent or continuous branch- rating is testing in accordance with NFPA 256-2003,Stan- circuit power. dard Methods of Fire Tests of Roof Coverings. (E) Between Equipment Racks and Premises Wiring III. Portable and Temporary Audio System System.Flexible cords and cables shall be permitted for the Installations electrical connection of permanently installed equipment racks to the premises wiring system to facilitate access to 640.41 Multipole Branch-Circuit Cable Connectors. equipment or for the purpose of isolating the technical Multipole branch-circuit cable connectors, male and fe- power system of the rack from the premises ground. Con- male, for power-supply cords and cables shall be so con- nection shall be made either by using approved plugs and structed that tension on the cord or cable is not transmitted receptacles or by direct connection within an approved en- to the connections. The female half shall be attached to the 70-542 NATIONAL ELECCRICAI.CODE 2008 Edition ARTICLE 040—AUDIO SIGNAL PROCESSING,AMPLIFICATION,AND REPRODUCTION EQUIPMENT 640.46 load end of the power supply cord or cable. The connec- (4) Other ac or do power supplies for shall be rated in amperes and designed so that differ- ently rated devices cannot be connected together. (E) Between Equipment Racks and Branch-Circuit Alternating-current multipole connectors shall be polar- Power.The supply to a portable equipment rack shall be by ized and comply with 406.6(A) and (B) and 406.9. means of listed extra-hard usage cords or cables, as defined Alternating-current or direct-current multipole connec- in Table 400.4. For outdoor portable or temporary use, the tors utilized for connection between loudspeakers and cords or cables shall be further listed as being suitable for amplifiers, or between loudspeakers, shall not be com- wet locations and sunlight resistant. Sections 520.5,520.10, patible with nonlocking 15- or 20-ampere rated connec- and 525.3 shall apply as appropriate when the following tors intended for branch-circuit power or with connectors conditions exist: rated 250 volts or greater and of either the locking or nonlocking type. Signal cabling not intended for such (1) Where equipment racks include audio and lighting loudspeaker and amplifier interconnection shall not be and/or power equipment permitted to be compatible with multipole branch-circuit (2) When using or constructing cable extensions, adapters, cable connectors of any accepted configuration. and breakout assemblies FPN: See 400.10 for pull at terminals. 640.43 Wiring of Equipment Racks. Equipment racks 640.42 Use of Flexible Cords and Cables. fabricated of metal I be .grounded. Nonmetallic racks with covers (if provided) removed shall not allow access to (A) Between Equipment and Branch-Circuit Power. Class 1, Class 3, or primary circuit power without the re- Power supply cords for audio equipment shall be listed and moval of covers over terminals or the use of tools. shall be permitted to be used where the interchange, main- tenance, or repair of such equipment is facilitated through Equipment racks shall be wired in a neat and work- the use of apower-supply cord, manlike manner. Wires, cables, structural components, or other equipment shall not be placed in such a manner as to (B) Between Loudspeakers and Amplifiers, or Between prevent reasonable access to equipment power switches and Loudspeakers. Flexible cords and cables used to connect resettable or replaceable circuit overcurrent protection devices. loudspeakers to each other or to an amplifier shall comply Wiring that exits the equipment rack for connection to with Article 400 and Article 725, respectively. Cords and other equipment or to a power supply shall be relieved of cables listed for portable use, either hard or extra-hard us- strain or otherwise suitably terminated such that a pull on age as defined by Article 400, shall also be permitted, Other the flexible cord or cable will not increase the risk of dam- listed cable types and assemblies, including optional hybrid age to the cable or connected equipment such as to cause an communications, signal, and optical fiber cables, shall be unreasonable risk of fire or electric shock. permitted. (C) Between Equipment and/or Between Equipment 640.44 Environmental Protection of Equipment. Por- Racks. Flexible cords and cables used for the distribu- table equipment not listed for outdoor use shall be permit- tion of audio signals between equipment shall comply ted only where appropriate protection of such equipment with Article 400 and Article 725, respectively. Cords and from adverse weather conditions is provided to prevent risk cables listed for portable use, either hard or extra-hard of fire or electric shock. Where the system is intended to service as defined by Article 400, shall also be permitted. remain operable during adverse weather, arrangements Other listed cable types and assemblies, including op- shall be made for maintaining operation and ventilation of tional hybrid communications, signal, and optical fiber heat-dissipating equipment. cables, shall be permitted. 640.45 Protection of Wiring. Where accessible to the {D) Between Equipment, Equipment Racks, and Power Supplies Other Than Branch-Circuit Power. Wiring be- public, flexible cords and cables laid or run on the ground tween the following power supplies, other than branch- or on the floor shall be covered with approved nonconduc- circuit power supplies, shall be installed, connected, or tive mats. Cables and mats shall be arranged so as not to wired in accordance with the requirements of this Code for present a tripping hazard. the voltage and power required: 640.46 Equipment Access. Equipment likely to present a (1) Storage batteries risk of fire, electric shock, or physical injury to the public (2) Transformers shall be protected by barriers or supervised by qualified (3) Transformer rectifiers personnel so as to prevent public access. 2008 Edition NATIONAL ELECTRICAL COIF. 70-543 645.1 ARTICLE 645—INFORMATION TECHNOLOGY EQUIPMENT (B) Cord-and-)Plug Connections. The data processing ARTICLE 645 system shall be permitted to be connected to a branch cir- Information Technology Equipment cuit by any of the following listed means: (1) FIexible cord and attachment plug cap not to exceed 645.1 Scope. This article covers equipment, power-supply 4.5 m (15 ft). wiring, equipment interconnecting wiring, and grounding of (2) Cord set assembly, where run on the surface of the information technology equipment and systems, including ter- floor, shall be protected against physical damage. minal units, in an information technology equipment room. (C) Interconnecting Cables. Separate data processing FPN: For further information, see NFPA 75-2003, Stan- units shall be permitted to be interconnected by means of dard for the Protection of Information Technology listed cables and cable assemblies.Where exposed to physi- Equipment• cal damage, the installation shall be protected by approved 645.2 Definition. means. Abandoned Supply Circuits and Interconnecting (D) Under Raised Floors. Power cables, communications Cables.Installed supply circuits and interconnecting cables cables,connecting cables, interconnecting cables,cord-and- that are not terminated at equipment and riot identified for plug connections,and receptacles associated with the infor- future use with a tag. mation technology equipment shall be permitted under a raised floor, provided the following conditions are met: 645.4 Special Requirements for Information Technol- (1) The raised floor is of suitable construction,and the area ogy Equipment Room. This article shall apply, provided under the floor is accessible. all of the following conditions are met: (2) The branch-circuit supply conductors to receptacles or (1) Disconnecting means complying with 645.10 are field-wired equipment are in rigid metal conduit, rigid provided. nonmetallic conduit, intermediate metal conduit, elec- (2) A separate heating/ventilating/air-conditioning(HVAC) trical metallic tubing, electrical nonmetallic tubing, system is provided that is dedicated for information metal wireway, nonmetallic wireway, surface metal technology equipment use and is separated from other raceway with metal cover, nonmetallic surface race- areas of occupancy. Any HVAC system that serves way, flexible metal conduit, liquidtight flexible metal other occupancies shall be permitted to also serve the conduit, or liquidtight flexible nonmetallic conduit, information technology equipment room if fire/smoke Type MI cable, Type MC cable, or Type AC cable. dampers are provided at the point of penetration of the These supply conductors shall be installed in accor- room boundary. Such dampers shall operate on activa- dance with the requirements of 300.11. tion of smoke detectors and also by operation of the disconnecting means required by 645.10. (3) Supply cords of listed information technology equip- ment in accordance with 645.5(B). FPN: For further information, see NFPA 75-2003, Stan- (4) Ventilation in the underfloor area is used for the infor- dard far the Protection of Information Technology Equip- menr, Chapter 10, 10.1, 10.1.1, 10.1.2, and 10.1.3. motion technology equipment room only, except as (3) Listed information technology equipment is installed. provided in 545.4(2).The ventilation system shall be so arranged, with approved smoke detection devices, that (4) The room is occupied only by those personnel needed upon the detection of fire or products of combustion in for the maintenance and functional operation of the the underfloor space, the circulation of air will cease. installed information technology equipment. ( (5) Openings in raised floors for cords and cables protect 5) The room is separated from other occupancies by fire- resistant-rated walls, floors, and ceilings with protected cards and cables against abrasion and minimize the entrance of debris beneath the floor. openings. FPN: For further information on room construction re- (6) Cables, other than those covered in (D)(2) and those quirements,see NFPA 75-2003,Standard for the Protection complying with {D)(6){a), {D)(6)(b), or(D)(6)(c}, shall of Information Technology Equipment, Chapter S. be listed as Type DP cable having adequate fire- resistant characteristics suitable for use under raised 6455 Supply Circuits and Interconnecting Cables. floors of an information technology equipment room. (A) Branch-Circuit Conductors. The branch-circuit con- a. Interconnecting cables enclosed in a raceway.. ductors supplying one or more units of a data processing b. Interconnecting cables listed with equipment manu- system shall have an ampacity not less than 125 percent of factured prior to July 1, 1994, being installed with the total connected load. that equipment. 7W-544 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 645— INFORMATION TECHNOLOGY EQUIPMENT 645.15 c. Cable type designations shown in Table 645.5 Shall be FPN: For signaling circuits,refer to Article 725;for optical permitted. Green, or green with one or more yellow fiber cables and raceways, refer to Article 770; and for stripes, insulated single-conductor cables, 4 AWG and communications circuits,refer to Article 800.For fire alarm larger, marked"for use in cable trays"or"for CT use" systems, refer to Article 760. shall be permitted for equipment grounding. 645.7 Penetrations. Penetrations of the fire-resistant room FPN: One method of defining fire resistance is by estab- boundary shall be in accordance with 300.21. lishing that the cables do not spread fire to the top of the tray in the"UL Flame Exposure,Vertical Tray Flame Test" 645.10 Disconnecting Means. An approved means shall in UL 1665-2000, Standard for Safety for Vertical-Tray be provided to disconnect power to all electronic equipment Fire-Propagation and Smoke Release Test for Electrical in the information technology equipment room or in desig- and Optical-Fiber Cables.The smoke measurements in the nated zones within the room. There shall also be a similar test method are not applicable. approved means to disconnect the power to all dedicated Another method of defining fire resistance is for the HVAC systems serving the room or designated zones and damage(char length)not to exceed 1.5 m(4 ft I I in.)when performing the CSA "Vertical Flame Test -- Cables in shall cause all required fire/smoke dampers to close. The Cable Trays," as described in CSA C22.2 No. 0.3-M-2001, control for these disconnecting means shall be grouped and Test Methods for Electrical Wires and Cables. identified and shall be readily accessible at the principal exit doors. A single means to control both the electronic Table 645.5 Cable Types Permitted Under Raised Floors equipment and HVAC systems in the room or in a zone shall be permitted. Where a pushbutton is used as a means Article Plenum Riser General Purpose to disconnect power, pushing the button in shall disconnect 336 TC the power. Where multiple zones are created', each zone 725 CL2P& CL3P CL2R & CL3R CL2, CL3 & PLTC shall have an approved means to confine fire or products of 727 ITC Combustion to within the zone. 760 NPLFP& FPLP NPLFR & FPLR NPLF& FPL 770 OFNP& OFCP OFNR & OFCR OFN & OFC Exception: Installations qualifying under the provisions of 400 CMP CMR CM & CMG Article 685. 820 CATVP CATVR CATV 645.11 Uninterruptible Power Supplies (UPSs). Except (E) Securing in Place. Power cables; communications for installations and constructions covered in 645.11(1) or cables; connecting cables, interconnecting cables;and asso- (2), UPS systems installed within the information technol- ciated boxes, connectors, plugs, and receptacles that are ogy equipment room, and their supply and output circuits, listed as part of, or for, information technology equipment shall comply with 645.10. The disconnecting means shall shall not be required to be secured in place. also disconnect the battery from its load. (F) Abandoned Supply Circuits and Interconnecting (1) Installations qualifying under the provisions of Article Cables. The accessible portion of abandoned supply cir- 6$5 cuits and interconnecting cables shall be removed unless (2) Power sources limited to 750 volt-amperes or less de- rived either from UPS equipment or from battery cir- cuits integral to electronic equipment (G) Installed Supply Circuits and Interconnecting Cables Identified for Future Use, 645.15 Grounding, All exposed non—current-carrying (1) Supply circuits and interconnecting cables identified metal parts of an information technology system shall be for future use Shall be marked with a tag of sufficient bonded to the equipment grounding conductor in accor- dance with Article 250 or shall be double insulated. Power durability to withstand the environment involved. systems derived within listed information technology (2) Supply circuit tags and interconnecting cable tags shall equipment that supply information technology systems have the following information: through receptacles or cable assemblies supplied as part of a. Date identified for future use this equipment shall not be considered separately derived b. Date of intended use for the purpose of applying 250.20(D). Where signal refer- c. Information relating to the intended future use ence structures are installed, they shall be bonded to the equipment grounding conductor provided for the informa- 645.6 Cables Not in Information Technology Equip- tion technology equipment. ment Room. Cables extending beyond the information FPN No. 1: The bonding requirements in the product stan- technology equipment room shall be subject to the appli- dards governing this listed equipment ensure that it com- cable requirements of this Code. plies with Article 250. 2008 Edition NATIONAL ELECTRICAL CODs; 70-545 645.16 ARTICLE 647—SENSITIVE ELECTRONIC EQUIPMENT FPN No. 2: Where isolated grounding-type receptacles are (B) Junction Boxes. All junction box covers shall be used, see 250.146(D) and 406.2(D). clearly marked to indicate the distribution panel and the system voltage. 645.16 Marking. Each unit of an information technology system supplied by a branch circuit shall be provided with (C) Conductor identification. All feeders and branch- a manufacturer's nameplate, which shall also include the circuit conductors installed under this section shall be iden- input power requirements for voltage, frequency, and maxi- tified as to system at all splices and terminations by color, mum rated load in amperes, marking, tagging, or equally effective means.The means of identification shall be posted at each branch-circuit panel- 645.17 Power Distribution Units. Power distribution board and at the disconnecting means for the building. units that are used for information technology equipment (D) Voltage Drop.The voltage drop on any branch circuit shall be permitted to have multiple panelboards within a shall not exceed 1.5 percent.The combined voltage drop of single cabinet, provided that each panelboard has no more feeder and branch-circuit conductors shall not exceed than 42 overcurrent devices and the power distribution unit 2.5 percent. is utilization equipment listed for information technology application. (1) Fixed Equipment. The voltage drop on branch circuits supplying equipment connected using wiring methods in Chapter 3 shall not exceed 1.5 percent.The combined volt- age drop of feeder and branch-circuit conductors shall not exceed 2.5 percent. ARTICLE 647 (2) Cord-Connected Equipment. The voltage drop on Sensitive Electronic Equipment branch circuits supplying receptacles shall not exceed 1 percent. For the purposes of making this calculation, the load connected to the receptacle outlet shall be considered 647.1 Scope.This article covers the installation and wiring to be 50 percent of the branch-circuit rating. The combined 01' separately derived systems operating at 120 volts line- voltage drop of feeder and branch-circuit conductors shall to-line and 60 volts to ground for sensitive electronic not exceed 2.0 percent. equipment. FPN: The purpose of this provision is to limit voltage drop 647.3 General. Use of a separately derived 120-volt to 1.5 percent where portable cords may be used as a means single-phase 3-wire system with 60 volts on each of two of connecting equipment. ungrounded conductors to a grounded neutral conductor 647.5 Three-Phase Systems.Where 3-phase power is sup- shall be permitted for the purpose of reducing objectionable plied, a separately derived 6-phase "wye" system with 60 noise in sensitive electronic equipment locations, provided volts to ground installed under this article shall be con- the following conditions apply: figured as three separately derived 120-volt single-phase (1) The system is installed only in commercial or industrial systems having a combined total of no more than six occupancies. disconnects. (2) The system's use is restricted to areas under close su- pervision by qualified personnel. 647.6 Grounding. (3) All of the requirements in 647.4 through 647.8 are met. (A) General.The system shall be grounded as provided in 250.30 as a separately derived single-phase, 3-wire system. 647.4 Wiring Methods. (B) Grounding Conductors Required. Permanently wired (A) Panelboards and Overcurrent Protection. Use of utilization equipment and receptacles shall be grounded by standard single-phase panelboards and distribution equip- means of an equipment grounding conductor run with the ment with a higher voltage rating shall be permitted. The circuit conductors to an equipment grounding bus promi- system shall be clearly marked on the face of the panel or nently marked "Technical Equipment Ground" in the origi- on the inside of the panel doors. Common trip two-pole nating branch-circuit panelboard. The grounding bus shall circuit breakers or a combination two-pole fused discon- be connected to the grounded conductor on the line side of the netting means that are identified for use at the system volt- separately derived system's disconnecting means.The ground- age shall be provided for both ungrounded conductors in all ing conductor shall not be smaller than that specified in Table feeders and branch circuits. Branch circuits and feeders 250.122 and run with the feeder conductors. The technical shall be provided with a means to simultaneously discon- equipment grounding bus need not be bonded to the panel- nect all ungrounded conductors. board enclosure. Other grounding methods authorized 70-546 NATIONAL ELECTRICAL CODE 2009 Edition ARTICLE 650—PIPE ORGANS 650.6 elsewhere in this Code shall be permitted where the im- grounded conductors. The disconnecting means shall be lo- pedance of the grounding return path does not exceed the cated within sight of the luminaire or be capable of being impedance of equipment grounding conductors sized and locked in the open position. The provision for locking or installed in accordance with this article, adding a lock to the disconnecting means shall be installed FPN No. 1: See 250.122 for equipment grounding conduc- on or at the switch or circuit breaker used as the discon- tor sizing requirements where circuit conductors are ad- necting means and shall remain in place with or without the justed in size to compensate for voltage drop. lock installed. Portable means for adding a lock to the FPN No. 2: These requirements limit the impedance of the switch or circuit breaker shall not be permitted. ground fault path where only 60 volts apply to a fault con- dition instead of the usual 120 volts. (B) Luminaires. All luminaires shall be permanently in- stalled and listed for connection to a separately derived 647.7 Receptacles. system at 120 volts line-to-line and 60 volts to ground. (A) General. Where receptacles are used as a means of con- (C) Screw Shell. Luminaires installed under this section necting equipment, the following conditions shall be met: shall not have an exposed lamp screw shell. (1) All 15- and 20-ampere receptacles shall be GFCI protected. (2) All receptacle outlet strips, adapters, receptacle covers, and faceplates shall be marked with the following ARTICLE 650 words or equivalent: Pipe Organs WARNING -- TECHNICAL POWER Do not connect to lighting equipment. equipment use only. 650.1 Scope. This article covers those electrical circuits For i and parts of electrically operated pipe organs that are em- 6 ionic e en 0/1 protected ployed for the control of the sounding apparatus and key- GFCI (3) A 125-volt,single-phase, 15-or 20-ampere-rated recep- tacle having one of its current-carrying poles connected 650.3 Other Articles. Electronic organs shall comply with to a grounded circuit conductor shall be located within the appropriate provisions of Article 640. 1.8 m(6 ft)of all permanently installed 15-or 20-ampere- rated 60 1120-volt technical power-system receptacles. 650.4 Source of Energy. The source of power shall be a (4) All 125-volt receptacles used for 601120-volt technical transformer-type rectifier, the do potential of which shall power shall have a unique configuration and be identi- not exceed 30 volts dc. fied for use with this class of system. All 125-volt, single-phase, 15- or 20-ampere-rated receptacle outlets 650.5 Grounding. The rectifier shall be bonded to the and attachment plugs that are identified for use with equipment grounding conductor according to the provisions grounded circuit conductors shall be permitted in ma- in Article 250, Parts V, VI, VII, and VIII. chine rooms, control rooms, equipment rooms, equip- ment racks, and other similar locations that are re- 650.6 Conductors. Conductors shall comply with stricted to use by qualified personnel. 650.6(A) through (D). (B) Isolated Ground Receptacles. Isolated ground recep- (A) Size. Conductors shall be not less than 28 AWG for tacles shall be permitted as described in 250.146(D), how- electronic signal circuits and not less than 26 AWG for ever, the branch-circuit equipment grounding conductor electromagnetic valve supply and the like, A main shall be terminated as required in 647.6(B). common-return conductor in the electromagnetic supply shall not be less than 14 AWG. 647.8 Lighting Equipment. Lighting equipment installed under this article for the purpose of reducing electrical (B) Insulation. Conductors shall have thermoplastic or noise originating from lighting equipment shall meet the thermosetting insulation, conditions of 647.8(A) through (C). (C) Conductors to Be Cabled. Except for the common- (A) Disconnecting Means. All luminaires connected to return conductor and conductors inside the organ proper, the separately derived systems operating at 60 volts to ground, organ sections and the organ console conductors shall be and associated control equipment if provided, shall have a cabled.The common-return conductors shall be permitted un- disconnecting means that simultaneously opens all un- der an additional covering enclosing both cable and return 2008 Edition NATIONAL,ELECTRICAL CODE 70547 650.7 ARTICLE 660 X-RAY EQUIPMENT conductor, or they shall be permitted as a separate conductor 660.2 Definitions. and shall be permitted to be in contact with the cable. Long-Time Rating.A rating based on an operating interval (D) Cable Covering.Each cable shall be provided with an of 5 minutes or longer. outer covering, either Overall or on each of any subassem- Mobile. X-ray equipment mounted on a permanent base blies of grouped conductors. Tape shall be permitted in with wheels and/or casters for moving while completely place of a covering. Where not installed in metal raceway, assembled. the covering shall be resistant to flame spread, or the cable or each cable subassembly shall be covered with a closely Momentary Rating. A rating based on an operating inter- val that does not exceed 5 seconds. wound listed fireproof tape, FPN: One method of determining that cable is resistant to Portable. X-ray equipment designed to be hand-carried. flame spread is by testing the cable to the VW-1 (vertical- Transportable.X-ray equipment that is to be installed in a wire) flame test in the ANSiIUL 1581-2001, Reference vehicle or that may be readily disassembled for transport in Standard for Electrical Wires, Cables and Flexible Cords. a vehicle. 650.7 Installation of Conductors. Cables shall be se- 660.3 Hazardous (Classified) Locations. Unless identi- curely fastened in place and shall be permitted to be at- fied for the location, X-ray and related equipment shall not tached directly to the organ structure without insulating be installed or operated in hazardous (classified) locations. supports. Cables shall not be placed in contact with other conductors. FPN: See Article 517, Part IV, 650.8 Overcurrent Protection. Circuits shall be so ar- 660.4 Connection to Supply Circuit. ranged that 26 AWG and 28 AWG conductors shall be (A) Fixed and Stationary Equipment. Fixed and station- protected by an overcurrent device rated at not more than 6 ary X-ray equipment shall be connected to the power sup- amperes. Other conductor sizes shall be protected in accor- ply by means of a wiring method meeting the general re- dance with their ampacity. A common return conductor quirements of this Code. Equipment properly supplied by a shall not require overcurrent protection. branch circuit rated at not over 30 amperes shall be permit- ted to be supplied through a suitable attachment plug cap and hard-service cable or cord. (B) Portable, Mobile, and Transportable Equipment. ARTICLE 660 individual branch circuits shall not be required for portable, X-Ray Equipment mobile, and transportable X-ray equipment requiring a ca- pacity of not over 60 amperes. Portable and mobile types of X-ray equipment of any capacity shall be supplied through I. General a suitable hard-service cable or cord. Transportable X-ray equipment of any capacity shall be permitted to be con- 660.1 Scope.This article covers all X-ray equipment oper- nected to its power supply by suitable connections and ating at any frequency or voltage for industrial or other hard-service cable or cord. nonmedical or nondental use. (C) Over 600 Volts,Nominal. Circuits and equipment op- health care facilities.FPN: See Article 517, Pan V, for X-ray installations in erated at more than 600 volts, nominal, shall comply with Article 490. Nothing in this article shall be construed as specifying safeguards against the useful beam or stray X-ray radiation. 660.5 Disconnecting Means. A disconnecting means of adequate capacity for at least 50 percent of the input re- FPN No. 1: Radiation safety and performance require- quired for the momentary rating,or 100 percent of the input ments of several classes of X-ray equipment are regulated required for the long-time rating, of the X-ray equipment, under Public Law 90-602 and are enforced by the Depart- whichever is greater,shall be provided in the supply circuit. ment of Health and Human Services. The disconnecting means shall be operable from a location FPN No. 2: in addition, information on radiation protec- readily accessible from the X-ray control. For equipment tion by the National Council on Radiation Protection and connected to a 120-volt, nominal, branch circuit of 30 am- Measurements is published as Reports of the National Council on Radiation Protection and Measurement. These penes or less, agrounding-type attachment plug cap and reports can be obtained From NCRP Publications, 7910 receptacle of proper rating shall be permitted to serve as a Woodmont Ave., Suite 1016, Bethesda, MD 20814. disconnecting means. 70-548 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE W)—X-RAY EQUIPMENT 660.47 660.6 Rating of Supply Conductors and Overcurrent vice, shall be provided to control the load resulting from Protection. failures in the high-voltage circuit. (A) Branch-Circuit Conductors. The ampacity of supply 660.21 Portable and Mobile Equipment. Portable and branch-circuit conductors and the overcurrent protective mobile equipment shall comply with 660.20, but the devices shall not be less than 50 percent of the momentary manually controlled device shall be located in or on the rating or 100 percent of the long-time rating, whichever is equipment. greater. (B) Feeder Conductors.The rated ampacity of conductors 660.23 Industrial and Commercial Laboratory and overcurrent devices of a feeder for two or more branch Equipment. circuits supplying X-ray units shall not be less than 100 per- (A) Radiographic and Fluoroscopic Types. All radio- cent of the momentary demand rating [as determined by graphic- and fluoroscopic-type equipment shall be effectively 660.6(A)1 of the two largest X-ray apparatus plus 20 percent enclosed or shall have interlocks that de-energize the equip- of the momentary ratings of other X-ray apparatus. ment automatically to prevent ready access to live current- FPN: The minimum conductor size For branch and feeder carrying parts. circuits is also governed by voltage regulation require- (B) Diffraction and Irradiation Types. Diffraction- and ments. For a specific installation, the manufacturer usually specifies minimum distribution transformer and conductor irradiation-type equipment or installations not effectively sizes, rating of disconnect means, and overcurrent enclosed or not provided with interlocks to prevent access protection. to live current-carrying parts during operation shall be pro- vided with a positive means to indicate when they are en- 660.7 Wiring Terminals. X-ray equipment not provided ergized. The indicator shall be a pilot light, readable meter with a permanently attached cord or cord set shall be pro- deflection, or equivalent means. vided with suitable wiring terminals or leads for the con- nection of power-supply conductors of the size required by 660.24 Independent Control. Where more than one piece the rating of the branch circuit for the equipment. of equipment is operated from the same high-voltage cir- cuit, each piece or each group of equipment as a unit shall 660.8 Number of Conductors in Raceway. The number be provided with a high-voltage switch or equivalent dis- of control circuit conductors installed in a raceway shall be connecting means. This disconnecting means shall be con- determined in accordance with 300.17. structed, enclosed, or located so as to avoid contact by persons with its live parts. 660.9 Minimum Size of Conductors. Size 18 AWG or 16 AWG fixture wires, as specified in 725.49, and flexible cords shall be permitted for the control and operating cir- cuits of X-ray and auxiliary equipment where protected by 660.35 General. Transformers and capacitors that are part not larger than 20-ampere overcurrent devices, of an X-ray equipment shall not be required to comply with Articles 450 and 460. 660.10 Equipment Installations. All equipment for new X-ray installations and all used or reconditioned X-ray 660.36 Capacitors. Capacitors shall be mounted within equipment moved to and reinstalled at a new location shall enclosures of insulating material or grounded metal. be of an approved type. II. Control IV. Guarding and Grounding 660.47 General. 660.20 Fixed and Stationary Equipment. (A) High-Voltage Parts. All high-voltage parts, including (A) Separate Control Device. A separate control device, X-ray tubes, shall be mounted within grounded enclosures. in addition to the disconnecting means, shall be incorpo- Air,oil,gas,or other suitable insulating media shall be used rated in the X-ray control supply or in the primary circuit to to insulate the high voltage from the grounded enclosure, the high-voltage transformer. This device shall be a part of The connection from the high-voltage equipment to X-ray the X-ray equipment but shall be permitted in a separate tubes and other high-voltage components shall be made enclosure immediately adjacent to the X-ray control unit. with high-voltage shielded cables. (B) Protective Device. A protective device, which shall be (B) Low-Voltage Cables. Low-voltage cables connecting permitted to be incorporated into the separate control de- to oil-filled units that are not completely sealed, such as 2006 Edition NATIONAL ELECTRICAL CODE 70-549 660.48 ARTICLE 665—INDUCT70N AND DIELECTRIC HEATING EQUIPMENT transformers, condensers, oil coolers, and high-voltage 665.3 Other Articles, Unless specifically amended by this switches, shall have insulation of the oil-resistant type. article, wiring from the source of power to the heating equipment shall comply with Chapters 1 through 4. 660.48 Grounding. Non-current-carrying metal parts of X-ray and associated equipment (controls, tables, X-ray 665.4 Hazardous (Classified) Locations. Heating equip- tube supports, transformer tanks, shielded cables, X-ray ment shall not be installed in hazardous (classified) loca- tube heads, and so forth) shall be grounded in the manner tions as defined in Article 500 unless the equipment and specified in Article 250. Portable and mobile equipment wiring are designed and approved for the hazardous (clas- shall be provided with an approved grounding-type attach- sified) locations. ment plug cap. 665.5 Output Circuit. The output circuit shall include all Exception: Battery-operated equipment. output components external to the converting device, in- cluding contactors,switches,busbars,and other conductors. The current How from the output circuit to ground under operating and ground-fault conditions shall be limited to a ARTICLE 665 value that does not cause 50 volts or more to ground to Induction and Dielectric appear on any accessible part of the heating equipment and Heating Equipment its load.The output circuit shall be permitted to be isolated from ground. 1. General 665.7 Remote Control. 665.1 Scope. This article covers the construction and in- (A) Multiple Control Points. Where multiple control stallation of dielectric heating, induction heating, induction points are used for applicator energization,a means shall be melting, and induction welding equipment and accessories provided and interlocked so that the applicator can be en- for industrial and scientific applications. Medical or dental ergized from only one control point at a time. A means for applications,appliances, or line frequency pipeline and ves- de-energizing the applicator shall be provided at each con- seI heating are not covered in this article. trol point. FPN: See Article 427, Part V, for line frequency induction (B) Foot Switches. Switches operated by foot pressure heating of pipelines and vessels. shall be provided with a shield over the contact button to 665.2 Definitions. avoid accidental closing of a foot switch. Converting Device. That part of the heating equipment 665.10 Ampacity of Supply Conductors. The ampacity that converts input mechanical or electrical energy to the of supply conductors shall be determined by 665.10(A) voltage, current, and frequency suitable for the heating ap- or (B). plicator. A converting device shall consist of equipment using mains frequency, all static multipliers, oscillator-type (A) Nameplate Rating, The ampacity of conductors sup- units using vacuum tubes, inverters using solid-state de- Plying one or more pieces of equipment shall be not less than the sum of the nameplate ratings for the largest group vices, or motor generator equipment. of machines capable of simultaneous operation,plus 100 per- Dielectric Heating. Heating of a nominally insulating ma- cent of the standby currents of the remaining machines.Where terial due to its own dielectric losses when the material is standby currents are not given on the nameplate, the name- placed in a varying electric field. plate rating shall be used as the standby current. Heating Equipment.As used in this article,any equipment (B) Motor-Generator Equipment. The ampacity of sup- that is used for heating purposes and whose heat is gener- ply conductors for motor-generator equipment shall be de- ated by induction or dielectric methods. termined in accordance with Article 430, Part Il. Heating Equipment Applicator.The device used to trans- 665.11 Overcurrent Protection. Overcurrent protection fer energy between the output circuit and the object or mass for the heating equipment shall be provided as specified in to be heated. Article 240. This overcurrent protection shall be permitted Induction Heating, Melting, and Welding. The heating, to be provided separately or as a part of the equipment. melting,or welding of a nominally conductive material due to its own 12R losses when the material is placed in a 665.12 Disconnecting Means. A readily accessible discon- varying electromagnetic field. netting means shall be provided to disconnect each heating 70-550 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 668—ELECTROLYTIC CELLS 668.1 equipment from its supply circuit. The disconnecting means 665.24 Capacitors. The time and means of discharge shall shall be located within sight from the controller or be capable be in accordance with 460.6 for capacitors rated 600 volts, of being locked in the open position.The provision for locking nominal, and under. The time and means of discharge shall or adding a lock to the disconnecting means shall be installed be in accordance with 460.28 for capacitors rated over 600 on or at the switch or circuit breaker used as the disconnecting volts, nominal. Capacitor internal pressure switches con- means and shall remain in place with or without the lock nected to a circuit-interrupter device shall be permitted for installed. Portable means for adding a lock to the switch or capacitor overcurrent protection. circuit breaker shall not be permitted. The rating of this disconnecting means shall not be less 665.25 Dielectric Heating Applicator Shielding. Protect than the nameplate rating of the heating equipment. Motor- tive cages or adequate shielding shall be used to guard generator equipment shall comply with Article 430, Part dielectric heating applicators. Interlock switches shall be IX.The supply circuit disconnecting means shall be permit- used on all hinged access doors, sliding panels, or other ted to serve as the heating equipment disconnecting means easy means of access to the applicator. All interlock where only one heating equipment is supplied. switches shall be connected in such a manner as to remove all power from the applicator when any one of the access II. Guarding, Grounding, and Labeling doors or panels is open. 665.19 Component Interconnection. The interconnection 665.26 Grounding and Bonding. Bonding to the equip- components required for a complete heating equipment in- merit grounding conductor or inter-unit bonding, or both, stallation shall be guarded. shall be used wherever required for circuit operation, and for limiting to a safe value radio frequency voltages be- 665.20 Enclosures. The converting device (excluding the tween all exposed non--current-carrying parts of the equip- component interconnections) shall be completely contained ment and earth ground, between all equipment parts and within an enclosure(s) of noncombustible material. surrounding objects, and between such objects and earth ground. Such connection to the equipment grounding con- 665.21 Control Panels. All control panels shall be of ductor and bonding shall be installed in accordance with dead-front construction. Article 250, Parts lI and V. 665.22 Access to Internal Equipment. Access doors or FPN: Under certain conditions,contact between the object being heated and the applicator results in an unsafe condi- detachable access panels shall be employed for internal ac- tion, such as eruption ot'heated materials.This unsafe con- cess to heating equipment. Access doors to internal com- dition may be prevented by grounding of the object being panments containing equipment employing voltages from heated and ground detection, 150 volts to 1000 volts ac or do shall be capable of being lacked closed or shall be interlocked to prevent the supply 665,27 Marking. Each heating equipment shall be pro- circuit from being energized while the door(s) is open. The video with a nameplate giving the manufacturer's name and prevision for locking or adding a lock to the access doors model identification and the following input data: line shall be installed on or at the access door and shall remain volts, frequency, number of phases, maximum current,full- in place with or without the lock installed. load kilovolt-amperes (kVA), and full-load power factor. Access doors to internal compartments containing Additional data shall be permitted, equipment employing voltages exceeding 1000 volts ac or do shall be provided with a disconnecting means equipped with mechanical lockouts to prevent access while the heat- ing equipment is energized, or the access doors shall be ARTICLE 668 capable of being locked closed and interlocked to prevent Electrolytic Cells the supply circuit from being energized while the door(s) is open. Detachable panels not normally used for access to such parts shall be fastened in a manner that makes them 668.1 Scope. The provisions of this article apply to the inconvenient to remove. installation of the electrical components and accessory equipment of electrolytic cells, electrolytic cell lines, and 665,23 Warning Labels or Signs. Warning labels or signs process power supply for the production of aluminum, cad- that read"DANGER—HIGH VOLTAGE—KEEP OUT" mium, chlorine, copper, fluorine, hydrogen peroxide, mag- shall be attached to the equipment and shall be plainly visible nesium, sodium, sodium chlorate, and zinc. where persons might come in contact with energized parts Not covered by this article are cells used as a source of when doors are open or closed or when panels are removed electric energy and for electroplating processes and cells from compartments containing over 150 volts ac or dc. used for the production of hydrogen. 2008 Edition NATIONAL ELECTRICAL CODE 70-551 666.2 ARTICLE 668—ELECTROLYTIC CELLS FPN No. 1: In general, any cell line or group of cell lines meat, shall be required to comply with all applicable pro- operated as a unit for the production of a particular metal, visions of this Code. gas, or chemical compound may differ from any other cell lines producing the same product because of variations in t (C) Electrolytic Cell Lines. Electrolytic cell lines shall he particular raw materials used, output capacity, use of proprietary methods or process practices, or other modify- comply with the provisions of Chapters 1 through 4 except ing factors to the extent that detailed Code requirements as amended in 668.3(C)(1) through (C)(4). become overly restrictive and do not accomplish the stated purpose of this Code. (1) Conductors.The electrolytic cell line conductors shall FPN No. 2: For further information, see IEEE 463-1993, not be required to comply with the provisions of Articles Standard for Electrical Safety Practices in Electrolytic Cell 110, 210, 215, 220, and 225. See 668.11. Line Working Zones. (2) Overcurrent Protection. Overcurrent protection of electrolytic cell do process power circuits shall not be re- quired to comply with the requirements of Article 240. Cell Line. An assembly of electrically interconnected elec- trolytic cells supplied by a source of direct-current power. (3} Grounding. Equipment located or used within the electrolytic cell line working zone or associated with the Cell Line Attachments and Auxiliary Equipment. As ap- cell line direct-current power circuits shall not be required plied to this article, a term that includes, but is not limited to, to comply with the provisions of Article 250. auxiliary tartks; process piping; ductwork;structural supports; e (4) Working Zone. The electrolytic cells, cell line attach- exposed cell line conductors; conduits and other raceways; ments, and the wiring of auxiliary equipment and devices pumps, positioning equipment, and cell cutout or bypass elec- within the cell line working zone shall not be required to trical devices. Auxiliary equipment includes tools, welding comply with the provisions of Articles 110, 210, 215, 220, -machines, crucibles, and other portable equipment used for and 225. See 668.30. operation and maintenance within the electrolytic cell line working zone. FPN: See 668.15 for equipment, apparatus, and structural In the cell line working zone, auxiliary equipment in- component grounding. cludes the exposed conductive surfaces of ungrounded cranes and crane-mounted cell-servicing equipment. 668.10 Cell Line Working Zone. Electrically Connected. A connection capable of carrying (A) Area Covered. The space envelope of the cell line current as distinguished from connection through electro- working zone shall encompass spaces that meet any of the magnetic induction. following conditions: Electrolytic Cell. A tank or vat in which electrochemical (1) Is within 2.5 m (96 in.) above energized surfaces of reactions are caused by applying electric energy for the electrolytic cell lines or their energized attachments purpose of refining or producing usable materials. (2) Is below energized surfaces of electrolytic cell lines or their energized attachments, provided the headroom in Electrolytic Cell Line Working Zone.The space envelope the space beneath is less than 2.5 m (96 in.) wherein operation or maintenance is normally performed (3) Is within 1.0 m (42 in.) horizontally from energized on or in the vicinity of exposed energized surfaces of elec- surfaces of electrolytic cell lines or their energized at- trolytic cell lines or their attachments, tachments or from the space envelope described in 668.10(A)(1) or (A)(2) 668.3 Other Articles. (B) Area Not Covered. The cell line working zone shall {A} Lighting,Ventilating,Material Handling.Chapters 1 not be required to extend through or beyond walls, floors, through 4 shall apply to services, feeders, branch circuits, roofs, partitions, barriers, or the like. and apparatus for supplying lighting, ventilating, material handling, and the like that are outside the electrolytic cell 668.11 Direct-Current Cell Line Process Power Supply. line working zone. (A) Not Grounded. The direct-current cell line process (B) Systems Not Electrically Connected.Those elements power-supply conductors shall not be required to be of a cell line power-supply system that are not electrically grounded. connected to the cell supply system, such as the primary winding of a two-winding transformer, the motor of a (B) Metal Enclosures Grounded. All metal enclosures motor-generator set, feeders, branch circuits, disconnecting of power-supply apparatus for the direct-current cell line means, motor controllers, and overload protective equip- process operating at a power-supply potential between 70-552 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 668—ELECTROLYTIC CELLS 668.30 terminals of over 50 volts shall be grounded by either of ment used within the cell line working zone shall not be the following means: grounded. (1) Through protective relaying equipment Exception No. 1: Where the cell line voltage does not ex- (2) By a minimum 210 AWG copper grounding conductor teed 200 volts dc, these frames and enclosures shall be or a conductor of equal or greater conductance permitted to be grounded. (C) Grounding Requirements. The grounding connec- Exception No. 2: These frames and enclosures shall be tions required by 668.11(B) shall be installed in accordance permitted to be grounded where guarded. with 250.8, 250.10, 250.12, 250.68, and 250.70. (B) Isolating Transformers. Electrically powered, hand- 668.12 Cell Line Conductors. held, cord-connected portable equipment with ungrounded frames or enclosures used within the cell line working zone (A) Insulation and Material.Cell line conductors shall be shall be connected to receptacle circuits that have only un- either bare, covered, or insulated and of copper, aluminum, grounded conductors such as a branch circuit supplied by copper-clad aluminum, steel, or other suitable material. an isolating transformer with an ungrounded secondary. (B) Size. Cell line conductors shall be of such cross- (C) Marking. Ungrounded portable electrical equipment sectional area that the temperature rise under maximum shall be distinctively marked and shall employ plugs and load conditions and at maximum ambient shall not exceed receptacles of a configuration that prevents connection of the safe operating temperature of the conductor insulation this equipment to grounding receptacles and that prevents or the material of the conductor supports. inadvertent interchange of ungrounded and grounded por- (C) Connections. Cell line conductors shall be joined by table electrical equipments. bolted, welded, clamped, or compression connectors. 668.21 Power-Supply Circuits and Receptacles for Por- 668.13 Disconnecting Means. table Electrical Equipment. (A) More Than One Process Power Supply. Where more (A) Isolated Circuits. Circuits supplying power to un- than one direct-current cell line process power supply grounded receptacles for hand-held, cord-connected equip- serves the same cell line, a disconnecting means shall be ment shall be electrically isolated from any distribution sys- provided on the cell line circuit side of each power supply tem supplying areas other than the cell line working zone to disconnect it from the cell line circuit. and shall be ungrounded. Power for these circuits shall be supplied through isolating transformers. Primaries of such (B) Removable Links or Conductors. Removable links transformers shalt operate at not more than 600 volts be- or removable conductors shall be permitted to be used as tween conductors and shall be provided with proper over- the disconnecting means. current protection. The secondary voltage of such trans- formers shall not exceed 300 volts between conductors,and 668.14 Shunting Means. all circuits supplied from such secondaries shall be un- (A) Partial or Total Shunting. Partial or total shunting of grounded and shall have an approved overcurrent device of cell line circuit current around one or more cells shall be proper rating in each conductor. permitted. (B) Noninterchangeability. Receptacles and their mating (B) Shunting One or More Cells. The conductors, plugs for ungrounded equipment shall not have provision switches, or combination of conductors and switches used for a grounding conductor and shall be of a configuration for shunting one or more cells shall comply with the appli- that prevents their use for equipment required to be cable requirements of 668.12. grounded. 668.15 Grounding. For equipment, apparatus, and strut- (C) Marking. Receptacles on circuits supplied by an iso- tural components that are required to be grounded by pro- lating transformer with an ungrounded secondary shall be a visions of Article 668, the provisions of Article 250 shall distinctive configuration, shalt be distinctively marked, and apply, except a water pipe electrode shall not be required to shall not be used in any other location in the plant. be used. Any electrode or combination of electrodes de- scribed in 250.52 shall be permitted. 668.30 Fixed and Portable Electrical Equipment. 668.20 Portable Electrical Equipment. (A) Electrical Equipment Not Required to Be Grounded. Alternating-current systems supplying fixed (A) Portable Electrical Equipment Not to Be Grounded. and portable electrical equipment within the cell line work- The frames and enclosures of portable electrical equip- ing zone shall not be required to be grounded. 2008 Edition NATIONAL ELECTRICAL CODE 70-553 668.31 ARTICLE 669—ELECTROPLATING (B) Exposed Conductive Surfaces Not Required to Be 668.40 Enclosures. General-purpose electrical equipment Grounded. Exposed conductive surfaces, such as electrical enclosures shall be permitted where a natural draft ventila- equipment housings, cabinets, boxes, motors, raceways, tion system prevents the accumulation of gases. and the like, that are within the cell line working zone shall not be required to be grounded. (C) Wiring Methods. Auxiliary electrical equipment such as motors, transducers, sensors, control devices, and ARTICLE 669 alarms, mounted an an electrolytic cell or other energized Electroplating surface, shall be connected to premises wiring systems by any of the following means: (1) Multiconductor hard usage cord. 669.1 Scope. The provisions of this article apply to the (2) Wire or cable in suitable raceways or metal or nonme- installation of the electrical components and accessory tallic cable trays. If metal conduit, cable tray, armored equipment that supply the power and controls for electro- cable, or similar metallic systems are used, they shall plating, anodizing, electropolishing, and electrostripping. be installed with insulating breaks such that they do not For purposes of this article, the term electroplating shall be cause a potentially hazardous electrical condition. used to identify any or all of these processes. (D) Circuit Ooercurrent Protection. Circuit protection 669.3 General. Equipment for use in electroplating pro- shall not be required for control and instrumentation that cesses shall be identified for such service. are totally within the cell line working 'none. (E) Bonding. Bonding of fixed electrical equipment to the 669.5 Branch-Circuit Conductors. Branch-circuit con- energized conductive surfaces of the cell line, its attach- ductors supplying one or more units of equipment shall ments, or auxiliaries shall be permitted. Where fixed elec- have an ampacity of not less than 125 percent of the total trical equipment is mounted on an energized conductive connected load. The ampacities for busbars shall be in ac- surface, it shall be bonded to that surface, cordance with 366.23. 668.31 Auxiliary Nonelectrical Connections. Auxiliary 669.6 Wiring Methods. Conductors connecting the elec- nonelectrical connections, such as air hoses, water hoses, trolyte tank equipment to the conversion equipment shall be and the like, to an electrolytic cell, its attachments, or aux- in accordance with 669.6(A) and (B). iliary equipment shall not have continuous conductive re- inforcing wire, armor, braids, and the like. Hoses shall be (A) Systems Not Exceeding 50 Volts Direct Current. In- of a nonconductive material. sulated conductors shall be permitted to be run without insulated support, provided they are protected from physi- 668.32 Cranes and Hoists. cal damage. Bare copper or aluminum conductors shall be (A) Conductive Surfaces to Be Insulated from Ground. Permitted where supported on insulators. The conductive surfaces of cranes and hoists that enter the (B) Systems Exceeding 50 Volts Direct Current. Insu- cell line working zone shall not be required to be grounded. lated conductors shall be permitted to be run on insulated The portion of an overhead crane or hoist that contacts an supports, provided they are protected from physical dam- energized electrolytic cell or energized attachments shall be age. Bare copper or aluminum conductors shall be permit- insulated from ground. ted where supported on insulators and guarded against ac- (B) Hazardous Electrical Conditions. Remote crane or cidental contact up to the point of termination in hoist controls that could introduce hazardous electrical con- accordance with 114.27. ditions into the cell line working zone shall employ one or more of the following systems: 669.7 Warning Signs. Warning signs shall be posted to (1) Isolated and ungrounded control circuit in accordance indicate the presence of bare conductors. with 668.21(A) (2) Nonconductive rope operator 669.8 Disconnecting Means. (3) Pendant pushbutton with nonconductive supporting (A) More Than One Power Supply. Where more than means and having nonconductive surfaces or un- one power supply serves the same do system, a disconnect- grounded exposed conductive surfaces ing means shall be provided on the do side of each power (4) Radio supply. 70-554 NATIONAL ELECTRICAL.CODE 2008 Edition ARTICLE 670—INDUSTRIAL MACHIAIERY 670.4 (B) Removable Links or Conductors. Removable links (3) Ampere rating of largest motor, from the motor name- or removable conductors shall be permitted to be used as plate, or load the disconnecting means. (4) Short-circuit current rating of the machine industrial 669.9 Overcurrent Protection. Direct-current conductors control panel based on one of the following: shall be protected from overcurrent by one or more of the a. Short-circuit current rating of a listed and labeled machine control enclosure or assembly following: b. Short-circuit current rating established utilizing an (1} Fuses or circuit breakers approved method (2) A current-sensing device that operates a disconnecting means FPN: UL 508A-2001, Supplement SB,is an example of an (3) Other approved means approved method. (5) Electrical diagram number(s) or the number of the in- dex to the electrical drawings The full-load current shown on the nameplate shall not ARTICLE 670 be less than the sum of the full-load currents required for all motors and other equipment that may be in operation at Industrial' Machinery the same time under normal conditions of use. Where un- usual type loads,duty cycles,and so forth require oversized 670.1 Scope. This article covers the definition of, the conductors or permit reduced-size conductors, the required nameplate data for, and the size and overcurrent protection capacity shall be included in the marked "full-load cur- of supply conductors to industrial machinery. rent." Where more than one incoming supply circuit is to be provided, the nameplate shall state the preceding infor- FPN No. 1: For further information, see NFPA 79-2007, mation for each circuit. Electrical Standardfir Industrial Machinery, FPN No. 2: For information on the workspace require- FPN: See 430.22(E) and 430.26 for duty cycle requirements. ments for equipment containing supply conductor termi- nals,see 110.26. For information on the workspace require- (B) Overcurrent Protection. Where overcurrent protec- ments for machine power and control equipment, see tion is provided in accordance with 670.4(B), the machine NFPA 79--2007, Electrical Standard for Industrial shall be marked "overcurrent protection provided at ma- Machinery. chine supply terminals." 670.2 Definition. 670.4 Supply Conductors and Overcurrent Protection. Industrial Machinery (Machine). A power-driven ma- chine (or a group of machines working together in a coot- (A) Size,The size of the supply conductor shall be such as dinated manner), not portable by hand while working, that to have an ampacity not less than 125 percent of the full- is used to process material by cutting; forming; pressure; load current rating of all resistance heating loads plus electrical, thermal, or optical techniques; lamination; or a 125 Percent of the full-load current rating of the highest combination of these processes. It can include associated rated motor plus the sum of the full-load current ratings of equipment used to transfer material or foaling, including all other connected motors and apparatus, based on their fixtures, to assemble/disassemble, to inspect or test, or to duty cycle, that may be in operation at the same time. package. [The associated electrical equipment, including FPN No. 1: See the 0-2000-volt ampacity tables of Article the logic controller(s) and associated software or logic to- 310 for ampacity of conductors rated 600 volts and below, gether with the machine actuators and sensors, are consid- FPN No. 2: See 430.22(E) and 430.26 for duty cycle ered as part of the industrial machine.] requirements. • 670.3 Machine Nameplate Data. (B) Disconnecting Means. A machine shall be considered (A) Permanent Nameplate. A permanent nameplate shall as an individual unit and therefore shall be provided with be attached to the control equipment enclosure or machine disconnecting means. The disconnecting means shall be and shall be plainly visible after installation.The nameplate Permitted to be supplied by branch circuits protected by shall include the following information: either fuses or circuit breakers. The disconnecting means (1) Supply voltage, number of phases, frequency, and full- shall not be required to incorporate overcurrent protection. load current (C) Overcurrent Protection. Where furnished as part of (2) Maximum ampere rating of the short-circuit and the machine, overcurrent protection for each supply circuit ground-fault protective device shall consist of a single circuit breaker or set of fuses, the 2009 Edition NATIONAL ELECTRICAL CODE 70-555 675.I ARTICLE 675—ELECTRICALLY DRIVEN OR CONTROLLED IRRIGATInN MACHINES machine shall bear the marking required in 670.3, and the 675.3 Other Articles. These provisions are in addition to, supply conductors shall be considered either as feeders or or amendatory of, the provisions of Article 430 and other as taps as covered by 240.21. articles in this Code that apply except as modified in this The rating or setting of the overcurrent protective de- article. vice for the circuit supplying the machine shall not be greater than the sum of the largest rating or setting of the 675.4 Irrigation Cable. branch-circuit short-circuit and ground-fault protective de- vice provided with the machine, plus 125 percent of the (A) Construction. The cable used to interconnect enclo- sures on the structure of an irrigation machine shall be an full-load current rating of all resistance heating loads, plus assembly of stranded, insulated conductors with nonhygro- the sum of the full-load currents of all other motors and scopic and nonwicking filler in a core of moisture- and apparatus that could be in operation at the same time. flame-resistant nonmetallic material overlaid with a metal- Exception: Where one or more instantaneous trip circuit lic covering and jacketed with a moisture-, corrosion-, and breakers or motor short-circuit protectors are used for mo- sunlight-resistant nonmetallic material. for branch-circuit short-circuit and ground fault protection The conductor insulation shall be of a type listed in as permitted by 430.52(C), the procedure specified in Table 310.13(A) for an operating temperature of 75°C 670.4(C)for determining the tnaximu m rating of the pro- (167°F) and for use in wet locations. The core insulating tective device for the circuit supplying the machine shall material thickness shall not he less than 0.76 mm (30 mils), apply with the following provision: For the purpose of the and the metallic overlay thickness shall be not less than calculation, each instantaneous trip circuit breaker or mo_ 0.20 mm (8 mils).The jacketing material thickness shall be for short-circuit protector shall be asstuned to have a rat- not less than 1.27 mm (50 mils), ing not exceeding the maxinrwn percentage of motor full- A composite of power, control, and grounding conduc- load current permitted by Table 430.52 for the type of tors in the cable shall be permitted. machine .supply circuit protective device employed. (B) Alternate Wiring Methods.Installation of other listed Where no branch-circuit short-circuit and ground-fault cables complying with the construction requirements of protective device is provided with the machine, the rating 675.4(A) shall be permitted. or setting of the overcurrent protective device shall be based on 430.52 and 430.53, as applicable. (C) Supports. Irrigation cable shall be secured by straps, hangers, or similar fittings identified for the purpose and so installed as not to damage the cable. Cable shall be sup- ported at intervals not exceeding 1.2 m (4 ft). ARTICLE 675 (D) Fittings. Fittings shall be used at all points where irri- Electrieally Driven or Controlled gation cable terminates. The fittings shall be designed for Irrigation Machines use with the cable and shall be suitable for the conditions of service. I. General 675.5 More Than Three Conductors in a Raceway or Cable. The signal and control conductors of a raceway or 675.1 Scope. The provisions of this article apply to elec- cable shall not be counted for the purpose of derating the trically driven or controlled irrigation machines, and to the conductors as required in 310.15(B)(2)(a). branch circuits and controllers for such equipment. 675.6 Marking on Main Control Panel.The main control 675.2 Definitions. panel shall be provided with a nameplate that shall give the Center Pivot Irrigation Machine. A multimotored irriga- following information: tion machine that revolves around a central pivot and em- (1) The manufacturer's name, the rated voltage, the phase, ploys alignment switches or similar devices to control in- and the frequency dividual motors. (2) The current rating of the machine Collector Rings.An assembly of slip rings for transferring (3) The rating of the main disconnecting means and size of electric energy from a stationary to a rotating member. overcurrent protection required Irrigation Machine. An electrically driven or controlled 675.7 Equivalent Current Ratings. Where intermittent machine, with one or more motors, not hand-portable, and duty is not involved, the provisions of Article 430 shall be used primarily to transport and distribute water for agricul- used for determining ratings for controllers, disconnecting tural purposes. means, conductors, and the like. Where irrigation machines 70-556 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 675 ELECTRICALLY DRIVEN OR CONTROLLED IRRIGATION MACHINES 675.12 have inherent intermittent duty, the determinations of each motor and controller and shall be located as required equivalent current ratings in 675.7(A)and(B)shall be used. by Article 430, Part IX. The disconnecting means shall not be required to be readily accessible. (A) Continuous-Current Rating. The equivalent con- tinuous-current rating for the selection of branch-circuit 675.9 Branch-Circuit Conductors. The branch-circuit conductors and overcurrent protection shall be equal to conductors shall have an ampacity not less than specified in 125 percent of the motor nameplate full-load current rating 675.7(A) or 675.22(A). of the largest motor, plus a quantity equal to the sum of 67530 Several Motors on One Branch Circuit. each of the motor nameplate full-load current ratings of all remaining motors on the circuit, multiplied by the maxi- (A) Protection Required. Several motors, each not ex- mum percent duty cycle at which they can continuously ceeding 2 hp rating, shall be permitted to be used on an operate. irrigation machine circuit protected at not more than 30 p amperes at 600 volts, nominal, or less, provided all of the (B) hocked-Rotor Current. The equivalent locked-rotor following conditions are met: current rating shall be equal to the numerical sum of the (1) The full-load rating of any motor in the circuit shall not locked-rotor current of the two largest motors plus 100 per- exceed 6 amperes, cent of the sum of the motor nameplate full-load current (2) Each motor in the circuit shall have individual overload ratings of all the remaining motors on the circuit. protection in accordance with 430.32. 675.6 Disconnecting Means. (3) Taps to individual motors shall not be smaller than 14 AWG copper and not more than 7.5 m (25 ft) in (A) Main Controller. A controller that is used to start and length. stop the complete machine shall meet all of the following (B) Individual Protection Not Required. Individual requirements: branch-circuit short-circuit protection for motors and motor (1) An equivalent continuous current rating not less than controllers shall not be required where the requirements of specified in 675.7(A) or 675.22(A) 675.10(A) are met. (2) A horsepower rating not less than the value from Table 430.251(A) and Table 430.251(B), based on the 675.11 Collector Rings. equivalent locked-rotor current specified in 675.7(B) or (A) Transmitting Current for Power Purposes. Collec- 675.22(B) for rings shall have a current rating not less than 125 per- cent of the full-load current of the largest device served Exception: A listed molded case switch shall not require a plus the full-load current of all other devices served, or as horsepower rating. determined from 675.7(A) or 675.22(A). (B) Main Disconnecting Means. The main disconnecting (B) Control and Signal Purposes.Collector rings for con- means for the machine shall provide overcurrent protection, trol and signal purposes shall have a current rating not less shall be at the point of connection of electric power to the than 125 percent of the full-load current of the largest device machine, or shall be visible and not more than 15 m (50 ft) served plus the full-load current of all other devices served. from the machine, and shall be readily accessible and ca- pable of being locked in the open position. The provision {C) Grounding. The collector ring used for grounding for locking or adding a lock to the disconnecting means shall have a current rating not less than that sized in accor- shall be installed on or at the switch or circuit breaker used dance with 675.11(A). as the disconnecting means and shall'remain in place with (D) Protection. Collector rings shall be protected from the or without the lock installed. This disconnecting means expected environment and from accidental contact by shall have a horsepower and current rating not less than means of a suitable enclosure. required for the main controller. 675.12 Grounding. The following equipment shall be Exception No. 1: Circuit breakers without marked horse- grounded: power ratings shall be permitted in accordance with (1) All electrical equipment on the irrigation machine 430.109. (2) All electrical equipment associated with the irrigation Exception No. 2: A listed molded case switch without machine marked horsepower ratings shall be permitted. (3) Metal junction boxes and enclosures (C) Disconnecting Means for Individual Motors and (4) Control panels or control equipment that supplies or Controllers. A disconnecting means shall be provided to controls electrical equipment to the irrigation machine simultaneously disconnect all ungrounded conductors for 2008 Edition NATIONAL ELECTRICAL CODE 70-557 675.13 ARTICLE 680—SWIMMING POOLS,FOUNTAINS,AND SIMILAR INSTALLATIONS Exception: Grounding shall trot be required on machines gation machines, the determinations in 675.22(A) and (B) it-here all of the following provisions are met: shall be used. (a) The machine is elec•tricallY controlled but not elec- tricall y driven. (A) Continuous-Current Rating. The equivalent con- (b) The control voltage is 30 volts or less. tinuous-current rating for the selection of branch-circuit (c) The control or signal circuits are current limited as conductors and branch-circuit devices shall be equal to specified in Chapter 9, Tables 11(A) and Il(B). 125 percent of the motor nameplate full-load current rating of the largest motor plus 60 percent of the sum of the motor 675.13 Methods of Grounding. Machines that require nameplate full-load current ratings of all remaining motors grounding shall have a non-current-carrying equipment on the circuit. grounding conductor provided as an integral part of each (B) Locked-Rotor Current. The equivalent locked-rotor cord, cable, or raceway. This grounding conductor shall be current rating shall be equal to the numerical sum of two sized not less than the largest supply conductor in each times the locked-rotor current of the largest motor plus cord, cable, or raceway. Feeder circuits supplying power to 80 percent of the sum of the motor nameplate full-load irrigation machines shall have an equipment grounding current ratings of all the remaining motors on the circuit. conductor sized according to Table 250.122. 675.14 Bonding. Where electrical grounding is required on an irrigation machine, the metallic structure of the ma- ARTICLE 680 chine, metallic conduit, or metallic sheath of cable shall be connected to the grounding conductor. Metal-to-metal con- Swimming P0015' Fountains, with a part that is connected to the grounding conduc- and Similar Installations for and the non-current-carrying parts of the machine shall be considered as an acceptable bonding path. I. General 675.15 Lightning Protection. If an irrigation machine has 680.1 Scope. The provisions of this article apply to the a stationary point, a grounding electrode system in accor- construction and installation of electrical wiring for, and dance with Article 250, Part III, shall be connected to the equipment in or adjacent to, all swimming, wading, thera- machine at the stationary point for lightning protection. peutic, and decorative pools; fountains, hot tubs; spas; and hydromassage bathtubs, whether permanently installed or 675.16 Energy from More Than One Source, Equipment storable, and to metallic auxiliary equipment, such as within an enclosure receiving electric energy from more pumps, filters, and similar equipment. The term body of than one source shall not be required to have a disconnect- water used throughout Part I applies to all bodies of water ing means for the additional source, provided that its volt- covered in this scope unless otherwise amended. age is 30 volts or less and it meets the requirements of Part 680.2 Definitions. III of Article 725. Cord-and-Plug-Connected Lighting Assembly. A light- 675.17 Connectors. External plugs and connectors on the ing assembly consisting of a luminaire intended for instal- equipment shall be of the weatherproof type. lation in the wall of a spa, hot tub, or storable pool, and a Unless provided solely for the connection of circuits cord-and-plug-connected transformer. meeting the requirements of Part III of Article 725, external Dry-Niche Luminaire. A luminaire intended for installa- plugs and connectors shall be constructed as specified in tion in the wall of a pool or fountain in a niche that is 250.124(A). sealed against the entry of pool water. Equipment, Fixed. Equipment that is fastened or other- II. Center Pivot Irrigation Machines wise secured at a specific location. 675.21 General. The provisions of Part II are intended to Equipment, Portable. Equipment that is actually moved or cover additional special requirements that are peculiar to can easily be moved from one place to another in normal use. center pivot irrigation machines. See 675.2 for the defini- tion of Center Pivot Irrigation Machine. Equipment, Stationary. Equipment that is not easily moved from one place to another in normal use. 675,22 Equivalent Current Ratings. To establish ratings Forming Shell.A structure designed to support a wet-niche of controllers, disconnecting means, conductors, and the luminaire assembly and intended for mounting in a pool or like, for the inherent intermittent duty of center pivot irri- fountain structure. 70-558 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 680—SWIMMING POOLS, FOUNTAINS,ARID SIMILAR INSTALLATIONS 680.3 Fountain, Fountains, ornamental pools, display pools, and unit. Equipment can include pumps, air blowers, heaters, reflection pools. The definition does not include drinking lights, controls, sanitizes generators, and so forth. fountains. Self-Contained Therapeutic Tubs or Hydrotherapeutic Hydromassage Bathtub. A permanently installed bathtub Tanks. A factory-fabricated unit consisting of a therapeutic equipped with a recirculating piping system, pump, and tub or hydrotherapeutic tank with all water-circulating, associated equipment. It is designed so it can accept, circu- heating, and control equipment integral to the unit. Equip- late, and discharge water upon each use. ment may include pumps, air blowers, heaters, light con- Maximum Water Level The highest level that water can trols, sanitizer generators, and so forth. reach before it spills out. Spa or Hot Tub. A hydromassage pool, or tub for recre- ational or therapeutic use, not located in health care facili- No-Niche Luminaire. A luminaire intended for installation ties, designed for immersion of users, and usually having a above or below the water without a niche. filter, heater, and motor-driven blower. It may be installed Packaged Spa or Hot Tub Equipment Assembly. A indoors or outdoors, on the ground or supporting structure, factory-fabricated unit consisting of water-circulating, heat- or in the ground or supporting structure. Generally, a spa or ing, and control equipment mounted on a common base, hot tub is not designed or intended to have its contents intended to operate a spa or hot tub. Equipment can include drained or discharged after each use. pumps, air blowers, heaters, lights, controls, sanitizer gen- Storable Swimming, Wading, or Immersion Pool. Those erators, and so forth. that are constructed on or above the ground and are capable Packaged Therapeutic Tub or Hydrotherapeutic Tank of holding water to a maximum depth of 1.0 m (42 in.), or Equipment Assembly. A factory-fabricated unit consisting a pool with nonmetallic, molded polymeric walls or inflat- of water-circulating, heating, and control equipment able fabric walls regardless of dimension. mounted on a common base, intended to operate a thera- Through-Wall Lighting Assembly. A lighting assembly peutic tub or hydrotherapeutic tank. Equipment can include intended for installation above grade, on or through the pumps, air blowers, heaters, lights, controls, sanitizer gen- wall of a pool, consisting of two interconnected groups of erators, and so forth. components separated by the pool wall. Permanently Installed Decorative Fountains and Reflec- 'Wet-Niche Luminaire. A luminaire intended for installa- tion Pools.Those that are constructed in the ground, on the tion in a forming shell mounted in a pool or fountain ground, or in a building in such a manner that the fountain structure where the luminaire will be completely sur- cannot be readily disassembled for storage, whether or not rounded by water. served by electrical circuits of any nature. These units are primarily constructed for their aesthetic value and are not 680.3 Other Articles, Except as modified by this article, intended for swimming or wading. wiring and equipment in or adjacent to pools and fountains Permanently Installed Swimming, Wading, Immersion, shall comply with other applicable provisions of this Code, and Therapeutic Pools. Those that are constructed in the including those provisions identified in Table 680.3. ground or partially in the ground, and all others capable of holding water in a depth greater than 1.0 m(42 in.), and all pools installed inside of a building, regardless of water Table 680.3 Other Articles depth, whether or not served by electrical circuits of any Topic Section or Article nature. Pool. Manufactured or field-constructed equipment de- Wiring Chapters I-4 Junction box support 314.23 signed to contain water on a permanent or semipermanent Rigid polyvinyl chloride 352.12 basis and used for swimming, wading,immersion,or thera- conduit(Type PVC) peutic purposes. Reinforced thermosetting 355.12 resin conduit(Type Pool Cover, Electrically Operated. Motor-driven equip- RTRC) ment designed to cover and uncover the water surface of a Audio Equipment Article 640, Parts 1 and 11 pool by means of a flexible sheet or rigid frame. Adjacent to pools and 640.10 fountains Self-Contained Spa or Hot Tub. Factory-fabricated unit Underwater speakers* consisting of a spa or hot tub vessel with all water- *Underwater loudspeakers shall be installed in accordance with circulating, heating, and control equipment integral to the 680.27(A). 2008 Edition NATIONAL ELECTRICAL CODE 70-559 680.4 ARTICLE 680—SWIMMING POOLS.FOUNTAINS,AND SIMILAR INS'J'ALLATIONS 680.4 Approval of Equipment. All electrical equipment netted with a flexible cord and plug to facilitate the re- installed in the water, walls, or decks of pools, fountains, moval or disconnection for maintenance or repair. and similar installations shall comply with the provisions of this article. (A) Length.For other than storable pools, the flexible cord shall not exceed 900 turn (3 ft) in length. 680.5 Ground-Fault Circuit Interrupters. Ground-fault circuit interrupters (GFC[s} shall be self-contained units, (B) Equipment Grounding.The flexible cord shall have a circuit-breaker or receptacle types, or other listed types, copper equipment grounding conductor sized in accordance with 250.122 but not smaller than 12 AWG. The cord shall 680.6 Grounding. Electrical equipment shall be grounded terminate in a grounding-type attachment plug, in accordance with Parts V, Vl, and Vll of Article 250 and (C) Construction. The equipment grounding conductors connected by wiring methods of Chapter 3,except as modified shall be connected to a fixed metal part of the assembly. by this article.The following equipment shall be grounded: The removable part shall be mounted on or bonded to the (1) Through-wall lighting assemblies and underwater lumi- fixed metal part. naires, other than those low-voltage lighting products listed for the application without a grounding conductor 680.8 Overhead Conductor Clearances. Overhead con- (2) All electrical equipment located within 1.5 m (5 ft) of ductors shall meet the clearance requirements in this sec- the inside wall of the specified body of water tion. Where a minimum clearance from the water level is (3) All electrical equipment associated with the recirculat- given, the measurement shall be taken from the maximum ing system of the specified body of water water level of the specified body of water. (4) Junction boxes {A} Power. With respect to service drop conductors and (5) Transformer enclosures open overhead wiring,g, swimming pool and similar installa- (6) Ground-fault circuit interrupters tions shall comply with the minimum clearances given in (7) Panelboards that are not part of the service equipment Table 680.8 and illustrated in Figure 680.8. and that supply any electrical equipment associated FPN: Open overhead wiring as used in this article typically with the specified body of water refers to conductor(s) not in an enclosed raceway. 680.7 Cord-and-Plug-Connected Equipment. Fixed or (B) Communications Systems.Communication,radio, and stationary equipment, other than underwater luminaires, for television coaxial cables within the scope of Articles 800 a permanently installed pool shall be permitted to be con- through 820 shall be permitted at a height of not less Table 680.8 Overhead Conductor Clearances Insulated Cables,0-750 Volts to Ground,Supported on and Cabled Together All Other Conductors Voltage to Ground with a Solidly Grounded Bare Messenger or Solidly Grounded Neutral Conductor 0 through 15 kV Over 15 through 50 kV Clearance Parameters m ft m rt m ft A. Clearance in any direction 6.9 22.5 7.5 25 8.0 27 to the water level, edge of water surface, base or diving platform, or permanently anchored raft B. Clearance in any direction 4.4 14.5 5.2 17 5.5 18 to the observation stand, tower, or diving platform C. Horizontal limit of This limit shall extend to the outer edge of the structures listed clearance measured from in A and B of this table but not to less than 3 m (10 ft). inside wall of the pool 70-560 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 680—SWIMMING POOLS,FOUNTAINS,AND SIMILAR INSTALLATIONS 680.21 _ Table 680.10 Minimum Cover Depths e & Minimum Cover A l3 t3 E Wiring Method mm in. A Rigid metal conduit 150 6 Intermediate metal 150 6 Observation conduit stand Nonmetallic raceways 450 18 C POOL C listed for direct burial without Figure 680.8 Clearances from Pool Structures. concrete encasement Other approved 450 18 than 3.0 m (10 ft) above swimming and wading pools,diving raceways* structures, and observation stands, towers, or platforms. *Raceways approved for burial only where concrete encased shall require a concrete envelope not less than 50 mm (2 in.)thick. (C) Network-Powered Broadband Communications Systems. The minimum clearances for overhead network- permanently installed barrier that provides a 1.5 m (5 ft) powered broadband communications systems conductors reach path or greater.This horizontal distance is to be mea- from pools or fountains shall comply with the provisions in sured from the water's edge along the shortest path re- Table 680.8 for conductors operating at 0 to 750 volts to quired to reach the disconnect. ground. 680.9 Electric Pool Water Heaters. All electric pool wa- II. Permanently Installed Pools ter heaters shall have the heating elements subdivided into 680.20 General. Electrical installations at permanently in- loads not exceeding 48 amperes and protected at not over stalled pools shall comply with the provisions of Part I and 60 amperes. The ampacity of the branch-circuit conductors part II of this article. and the rating or setting of overcurrent protective devices shall not be less than 125 percent of the total nameplate- 680.21 Motors. rated load. (A) Wiring Methods. The wiring to a pool motor shall 680.10 Underground Wiring Location. Underground comply with (A)(1) unless modified for specific circum- wiring shall not be permitted under the pool or within the stances by (A)(2), (A)(3), (A)(4), or(A)(5). area extending 1.5 m (5 ft) horizontally from the inside (1) General. The branch circuits for pool-associated mo- wall of the pool unless this wiring is necessary to supply tors shall be installed in rigid metal conduit, intermediate pool equipment permitted by this article. Where space limi- metal conduit, rigid polyvinyl chloride conduit, reinforced tations prevent wiring from being routed a distance 1.5 m thermosetting resin conduit,or Type MC cable listed for the (5 ft)or more from the pool, such wiring shall be permitted location. Other wiring methods and materials shall be per- where installed in complete raceway systems of rigid metal mitted in specific locations or applications as covered in conduit, intermediate metal conduit, or a nonmetallic race- this section. Any wiring method employed shall contain an way system. All metal conduit shall be corrosion resistant insulated copper equipment grounding conductor sized in and suitable for the location. The minimum cover depth accordance with 250.122 but not smaller than 12 AWG. shall be as given in Table 6$0.10. (2) On or Within Buildings.Where installed on or within 680.11 Equipment Rooms and Pits. Electrical equipment buildings, electrical metallic tubing shall be permitted. shall not be installed in rooms or pits that do not have (3) Flexible Connections. Where necessary to employ drainage that adequately prevents water accumulation dur- flexible connections at or adjacent to the motor, liquidtight ing normal operation or filter maintenance. flexible metal or liquidtight flexible nonmetallic conduit 680.12 Maintenance Disconnecting Means. One or more With approved fittings shall be permitted. means to simultaneously disconnect all ungrounded con- (4) One-Family Dwellings. In the interior of dwelling ductors shall be provided for all utilization equipment other units, or in the interior of accessory buildings associated than lighting. Each means shall be readily accessible and with a dwelling unit, any of the wiring methods recognized within sight from its equipment and shall be located at least in Chapter 3 of this Code that comply with the provi- 1.5 m (5 ft) horizontally from the inside walls of a pool, sions of this section shall be permitted. Where run in a spa, or hot tub unless separated from the open water by a cable assembly, the equipment grounding conductor shall 2008 Edition NATIONAL ELECTRICAL CODE 70-561 680.22 ARTICLE 680—SWIMMING POOLS,FOUNTAINS,AND SIMILAR INSTALLATIONS be permitted to be uninsulated, but it shall be enclosed appliance connected to the receptacle would follow without within the outer sheath of the cable assembly. piercing a floor, wall, ceiling,doorway with hinged or sliding (5) Cord-and-Plug Connections. Pool-associated motors door, window opening, or other effective permanent barrier. shall be permitted to employ cord-and-plug connections. (B) GFCI Protection- Outlets supplying pool pump mo- The flexible cord shall not exceed 900 mm (3 ft) in length. tors from branch circuits with short-circuit and ground-fault The flexible cord shall include an equipment grounding protection rated 15 or 20 amperes, 125 volt or 240 volt, conductor sized in accordance with 250.122 and shall ter- single phase, whether by receptacle or direct connection, urinate in a grounding-type attachment plug. shall be provided with ground-fault circuit-interrupter pro- (B) Double Insulated Pool Pumps. A listed cord-and- tection for personnel. plug-connected pool pump incorporating an approved system (C) Luminaires, Lighting Outlets, and Ceiling-Sus- of double insulation that provides a means for grounding only pended (Paddle) Fans. the internal and nonaccessible, non—current-carrying metal parts of the pump shall be connected to any wiring method (1) New Outdoor Installation Clearances. In outdoor recognized in Chapter 3 that is suitable for the location.Where pool areas, luminaires, lighting outlets, and ceiling- the bonding grid is connected to the equipment grounding suspended(paddle) fans installed above the pool or the area conductor of the motor circuit in accordance with the second extending 1.5 m (5 ft) horizontally from the inside walls of paragraph of 680.26(B)(4), the branch-circuit wiring shall the pool shall be installed at a height not less than 3.7 m comply with 680.21(A). (12 ft) above the maximum water level of the pool. 680.22 Area Lighting, Receptacles, and Equipment. (2) Indoor Clearances. For installations in indoor pool areas, the clearances shall be the same as for outdoor areas (A) Receptacles. unless modified as provided in this paragraph. if the branch circuit supplying the equipment is protected by a ground- (1) Circulation and Sanitation System,Location.Recep- fault circuit interrupter, the following equipment shall be tacles that provide power for water-pump motors or for permitted at a height not less than 2.3 m (7 ft 6 in.) above other loads directly related to the circulation and sanitation the maximum pool water level: system shall be located at least 3.0 m (10 ft) from the inside (1) Totally enclosed luminaires walls of the pool, or not less than 1.83 m (6 ft) from the inside walls of the pool if they meet all of the following (2) Ceiling-suspended (paddle) fans identified for use be- inside neath ceiling structures such as provided on porches or (1) Consist of single receptacles patios (2) Employ a locking configuration (3) Existing Installations. Existing luminaires and light- (3) Are of the grounding type ing outlets located less than 1.5 m (5 ft) measured horizon- tally from the inside walls of a pool shall be not less than {4) Have GFCI protection 1.5 m (5 ft) above the surface of the maximum water level, (2) Other Receptacles, Location. Other receptacles shall be shall be rigidly attached to the existing structure, and shall not less than 1.83 m (6 ft) from the inside walls of a pool. be protected by a ground-fault circuit interrupter. (3) Dwelling Unit(s). Where a permanently installed pool (4) GFCI Protection in Adjacent Areas. Luminaires, is installed at a dwelling unit(s), no fewer than one 125- lighting outlets, and ceiling-suspended (paddle) fans in- volt, 15- or 20-ampere receptacle on a general-purpose stalled in the area extending between 1.5 m (5 ft) and 3.0 m branch circuit shall be located not less than 1.83 m (6 ft) (10 ft) horizontally from the inside walls of a pool shall be from, and not more than 6.0 m (20 ft) from, the inside wall protected by a ground-fault circuit interrupter unless in- of the pool. This receptacle shall be located not more than stalled not less than t.5 m (5 ft) above the maximum water 2.0 m (6 ft 6 in.) above the floor, platform, or grade level level and rigidly attached to the structure adjacent to or serving the pool. enclosing the pool. (4) GFCI Protection. All 15- and 20-ampere, single- (5) Cord-and-Plug-Connected Luminaires. Cord-and- phase, 125-volt receptacles located within 6.0 m (20 ft) of plug-connected luminaires shall comply with the require- the inside walls of a pool shall be protected by a ground- ments of 680.7 where installed within 4.9 m (16 ft) of any fault circuit interrupter. point on the water surface, measured radially. (5) Measurements. In determining the dimensions in this (D) Switching Devices. Switching devices shall be located section addressing receptacle spacings, the distance to be at least 1.5 m (5 ft) horizontally from the inside walls of a measured shall be the shortest path the supply cord of an pool unless separated from the pool by a solid fence, wall, 70-562 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 680—SWIMMING POOLS,FOUNTAINS,AND SIMILAR INSTALLATIONS 680.23 or other permanent barrier. Alternatively, a switch that is (1) Have the lens adequately guarded to prevent contact by listed as being acceptable for use within 1.5 m (5 ft) shall any person be permitted. (2) Be listed for use without a guard (E) Other Outlets.Other outlets shall be not less than 3.0 m (7) Dependence on Submersion. Luminaires that depend (10 ft)from the inside walls of the pool.Measurements shall on submersion for safe operation shall be inherently protected be determined in accordance with 680.22(A)(5). against the hazards of overheating when not submerged. FPN: Other outlets may include, but are not limited to, (8) Compliance. Compliance with these requirements remote-control, signaling, fire alarm, and Communications shall be obtained by the use of a listed underwater lumi- cireuits. naire and by installation of a listed ground-fault circuit interrupter in the branch circuit or a listed transformer for 680.23 Underwater Luminaires.This section covers all lu- luminaires operating at not more than 15 volts. minaires installed below the normal water level of the pool. (B) Wet-Niche Luminaires. (A) General. (1) Forming Shells. Forming shells shall be installed for (1) Luminaire Design, Normal Operation.The design of the mounting of all wet-niche underwater luminaires and an underwater luminaire supplied from a branch circuit ei- shall be equipped with provisions for conduit entries. Metal ther directly or by way of a transformer meeting the re- parts of the luminaire and forming shell in contact with the quirements of this section shall be such that, where the pool water shall be of brass or other approved corrosion- luminaire is properly installed without a ground-fault cir- resistant metal.All forming shells used with nonmetallic con- cuit interrupter, there is no shock hazard with any likely duit systems, other than those that are part of a listed low- combination of fault conditions during normal use (not voltage lighting system not requiring grounding, shall include relamping). provisions for terminating an 8 AWG copper conductor. (2) Transformers.Transformers used for the supply of un- (2) Wiring Extending Directly to the Forming Shell. derwater luminaires, together with the transformer enclo- Conduit shall be installed from the forming shell to a junc- sure, shall be listed as a swimming pool and spa trans- tion box or other enclosure conforming to the requirements former. The transformer shall be an isolated winding type in 680.24. Conduit shall be rigid metal, intermediate metal, with an ungrounded secondary that has a grounded metal liquidtight flexible nonmetallic, or rigid nonmetallic. barrier between the primary and secondary windings. (a) Metal Conduit. Metal conduit shall be approved and shall be of brass or other approved corrosion-resistant metal. (3) GFCI Protection, Relamping. A ground-fault circuit (b) Nonmetallic Conduit. Where a nonmetallic conduit interrupter shall be installed in the branch circuit supplying is used, an 8 AWG insulated solid or stranded copper bond- luminaires operating at more than 15 volts such that there is ing jumper shall be installed in this conduit unless a listed no shock hazard during relamping. The installation of the low-voltage lighting system not requiring grounding is ground-fault circuit interrupter shall be such that there is no used. The bonding jumper shall be terminated in the form- shock hazard with any likely fault-condition combination ing shell,junction box or transformer enclosure,or ground- that involves a person in a conductive path from any un- fault circuit-interrupter enclosure. The termination of the 8 grounded part of the branch circuit or the luminaire to AWG bonding jumper in the forming shell shall be covered ground. with, or encapsulated in, a listed potting compound to pro- (4) Voltage Limitation. No luminaires shall be installed tect the connection from the possible deteriorating effect of for operation on supply circuits over 150 volts between pool water. conductors. (3) Equipment Grounding Provisions for Cords. Wet- niche luminaires that are supplied by a flexible cord or (5) Location, Wall-Mounted Luminaires. Luminaires cable shall have all exposed non-current-carrying metal mounted in walls shall be installed with the top of the parts grounded by an insulated copper equipment ground- luminaire lens not less than 450 mm (18 in.) below the ing conductor that is an integral part of the cord or cable. normal water level of the pool, unless the luminaire is listed This grounding conductor shall be connected to a grounding and identified for use at lesser depths.No luminaire shall be terminal in the supply junction box, transformer enclosure, or installed less than 100 mm (4 in.) below the normal water other enclosure.The grounding conductor shall not be smaller level of the pool. than the supply conductors and not smaller than 16 AWG. (6) Bottom-Mounted Luminaires.A luminaire facing up- (4) Luminaire Grounding Terminations. The end of ward shall comply with either (1) or (2): the flexible-cord jacket and the flexible-cord conductor 2008 Edition NATIONAL ELECTRICAL CODE 70-563 680.23 ARTICLE 080—SWIMMING POOLS,FOUNTAINS,AND SIMILAR INSTALLATIONS terminations within a luminaire shall be covered with, or duit, liquidtight flexible nonmetallic conduit, rigid polyvi- encapsulated in, a suitable potting compound to prevent nyl chloride conduit, Or reinforced thermosetting resin the entry of water into the luminaire through the cord or conduit. Where installed on buildings, electrical metallic its conductors. In addition, the grounding connection tubing shall be permitted, and where installed within build- within a luminaire shall be similarly treated to protect ings, electrical nonmetallic tubing, Type MC cable, electri- such connection from the deteriorating effect of pool cal metallic tubing, or Type AC cable shall be permitted.In water in the event of water entry into the luminaire. all cases, an insulated equipment grounding conductor (5) Luminaire Bonding. The luminaire shall be bonded sized in accordance with Table 250.122 but not less than to, and secured to, the forming shell by a positive locking 12 AWG shall be required. device that ensures a low-resistance contact and requires a too] Exception: Where connecting to transformers for pool to remove the luminaire from the forming shell. Bonding shall lights, liquidtight flexible metal conduit or liquidtight flex- not be required for luminaires that are listed for the application ible nonmetallic conduit shall be permitted. The length and have no non—current-carrying metal parts. shall not exceed 1,8 m (6 ft)for any one length or exceed (6) Servicing,All wet-niche luminaires shall be removable 3.0 in (10 ft) in total length used. Liquidtight flexible non- from the water for inspection, relamping, or other mainte- metallic conduit, Type B (LFNC-B), .shall be permitted in nance.The forming shell location and length of cord in the lengths longer than 1.S m (6 ft). forming shell shall permit personnel to ,place the removed (2) Equipment Grounding.Through-wall lighting assem- luminaire on the deck or other dry location for such main- blies, wet-niche, dry-niche, or no-niche luminaires shall be tenance. The luminaire maintenance location shalt be ac- connected to an insulated copper equipment grounding con- cessible without entering or going in the pool water. ductor installed with the circuit conductors. The equipment grounding conductor shall be installed without joint or splice (C) Dry-Niche Luminaires. except as permitted in (17)(2)(a) and (F)(2)(b). The equipment (1) Construction. Adry-niche luminaire shall be provided grounding conductor shall be sized in accordance with Table with a provision for drainage of water and a means for 250.122 but shall not be smaller than l2 AWG. accommodating one equipment grounding conductor for Exception: An equipment grounding conductor between each conduit entry. the wiring chamber of the secondary winding of a trans- (2) Junction Box.A junction box shall not be required but, ,farmer and a junction box shall be sized in accordance with if used, shall not be required to be elevated or located as the overcurrent device in this circuit. specified in 680.24(A)(2) if the luminaire is specifically (a) If more than one underwater luminaire is supplied identified for the purpose, by the same branch circuit, the equipment grounding con- ductor, installed between the junction boxes, transformer (D) No-Niche Luminaires. A no-niche luminaire shall enclosures, or other enclosures in the supply circuit to wet- meet the construction requirements of 680.23(B)(3) and be niche luminaires, or between the field-wiring compartments installed in accordance with the requirements of 680.23(B). of dry-niche luminaires, shall be permitted to be terminated Where connection to a forming shell is specified, the con- on grounding terminals. nection shall be to the mounting bracket. (b) If the underwater luminaire is supplied from a transformer, ground-fault circuit interrupter, clock-operated (E) Through-Wall Lighting Assembly. A through-wall switch, or a manual snap switch that is located between the lighting assembly shall be equipped with a threaded entry panelboard and a junction box connected to the conduit that or hub, or a nonmetallic hub, for the purpose of accommo- extends directly to the underwater luminaire, the equipment dating the termination of the supply conduit. A through- grounding conductor shall be permitted to terminate on wall lighting assembly shall meet the construction require- grounding terminals on the transformer,ground-fault circuit ments of 680.23(B)(3) and be installed in accordance with interrupter, clock-operated switch enclosure, or an outlet the requirements of 680.23. Where connection to a forming box used to enclose a snap switch. shell is specified, the connection shall be to the conduit termination point. (3) Conductors. Conductors on the load side of a ground- fault circuit interrupter or of a transformer, used to comply (F) Branch-Circuit Wiring. with the provisions of 680.23(A)(8), shall not occupy race- (1) Wiring Methods. Branch-circuit wiring on the supply Ways, boxes, or enclosures containing other conductors un- side of enclosures and junction boxes connected to conduits less one of the following conditions applies: run to wet-niche and no-niche luminaires, and the field (1) The other conductors are protected by ground-fault cir- wiring compartments of dry-niche luminaires, shall be in- cuit interrupters. stalled using rigid metal conduit, intermediate metal con- (2) The other conductors are grounding conductors. 70-564 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 680—SWIMMING POOLS, FOUNTAINS,AND SIMILAR INSTALLATIONS 680.25 (3) The other conductors are supply conductors to a feed- (1) Equipped with threaded entries or hubs or a nonmetal- through-type ground-fault circuit interrupter. lic hub (4) Ground-fault circuit interrupters shall be permitted in a (2) Comprised of copper, brass, suitable plastic, or other panelboard that contains circuits protected by other approved corrosion-resistant material than ground-fault circuit interrupters. (3) Provided with an approved seal,such as duct seal at the conduit connection, that prevents circulation of air be- 680.24 Junction Boxes and Electrical Enclosures for tween the conduit and the enclosures Transformers or Ground-Fault Circuit Interrupters. (4) Provided with electrical continuity between every con- (A) Junction Boxes. A junction box connected to a con- nected metal conduit and the grounding terminals by duit that extends directly to a forming shell or mounting means of copper, brass, or other approved corrosion- bracket of a no-niche luminaire shall meet the requirements resistant metal that is integral with the box of this section. (2) Installation. (1) Construction. The junction box shall be listed as a (a) Vertical Spacing. The enclosure shall be located not swimming pool junction box and shall comply with the less than 100 mm (4 in.), measured from the inside of the following conditions: bottom of the box, above the ground level, or pool deck, or (1) Be equipped with threaded entries or hubs or a nonme- not less than 200 mm (8 in.) above the maximum pool tallic hub water level, whichever provides the greater elevation. (2) Be comprised of copper,brass, suitable plastic,or other (b) Horizontal Sparing. The enclosure shall be located approved corrosion-resistant material not less than 1.2 m (4 ft) from the inside wall of the pool, (3) Be provided with electrical continuity between every unless separated from the pool by a solid fence, wall, or connected metal conduit and the grounding terminals other permanent barrier. by means of copper, brass, or other approved corrosion-resistant metal that is integral with the box (C) Protection. Junction boxes and enclosures mounted above the grade of the finished walkway around the pool (2) Installation. Where the luminaire operates over 15 shall not be located in the walkway unless afforded addi- volts, the junction box location shall comply with (A)(2)(a) tional protection, such as by location under diving boards, and (A)(2)(b). Where the luminaire operates at 15 volts or adjacent to fixed structures, and the like. less,the junction box location shall be permitted to comply with (A)(2)(c). (D) Grounding Terminals. Junction boxes, transformer (a) Vertical Spacing. The junction box shall be located enclosures, and ground-fault circuit-interrupter enclosures not less than 100 mm (4 in.), measured from the inside of connected to a conduit that extends directly to a forming the bottom of the box,above the ground level,or pool deck, shell or mounting bracket of a no-niche luminaire shall be or not less than 200 mm (8 in.) above the maximum pool provided with a number of grounding terminals that shall water level, whichever provides the greater elevation, be no fewer than one more than the number of conduit (b) Horizontal Spacing. The junction box shall be lo- entries. cated not less than 1.2 m (4 ft) from the inside wall of the pool, unless separated from the pool by a solid fence, wall, (E) Strain Relief. The termination of a flexible cord of an or other permanent barrier. underwater luminaire within a junction box, transformer (c) Flush neat Box. If used on a lighting system oper- enclosure, ground-fault circuit interrupter, or other enclo- ating at 15 volts or less, a flush deck box shall be permitted sure shall be provided with a strain relief. if both of the following apply: (F) Grounding. The equipment grounding conductor ter- (1) An approved potting compound is used to fill the box urinals of a junction box, transformer enclosure, or other to prevent the entrance of moisture. enclosure in the supply circuit to a wet-niche or no-niche (2) The flush deck box is located not less than 1.2 m (4 ft) luminaire and the field-wiring chamber of a dry-niche lu- from the inside wall of the pool. minaire shall be connected to the equipment grounding ter- (B) Other Enclosures. An enclosure for a transformer, minal of the panelboard. This terminal shall be directly ground-fault circuit interrupter, or a similar device con- connected to the panelboard enclosure. nected to a conduit that extends directly to a forming shell or mounting bracket of a no-niche luminaire shall meet the 680.25 Feeders.These provisions shall apply to any feeder on the supply side of panelboards supplying branch circuits requirements of this section. for pool equipment covered in Part I1 of this article and on (1) Construction.The enclosure shall be listed and labeled the load side of the service equipment or the source of a for the purpose and meet the following requirements: separately derived system. 2008 Edition NATIONAL ELECTRICAL CODE 70-565 680.26 ARTICLE 680—SWIMMING POOLS.FOUNTAINS.AND SIMILAR INSTALLATIONS (A) Wiring Methods. Feeders shall be installed in rigid extended or attached to remote panelboards, service equip- metal conduit, intermediate metal conduit, liquidtight ilex- ment, or electrodes. ible nonmetallic conduit, rigid polyvinyl chloride conduit, (1) Conductive Pool Shells. Bonding to conductive pool or reinforced thermosetting resin conduit. Electrical metal- shells shall be provided as specified in 680.26(B)(1)(a) or lic tubing shall be permitted where installed on or within a building, and electrical nonmetallic tubing shall be permit- (11)(1)(b). Poured concrete, pneumatically applied or red where installed within a building. Aluminum conduits tered coatings shall,concrete, and concrete block with painted or plas- shall not be permitted in the pool area where subject to l all 11e considered conductive materials due to water permeability and porosity. Vinyl liners and corrosion. fiberglass composite shells shall be considered to be non- Exception: An existing feeder between an existing remote conductive materials. panelboard and service equipment shall be permitted to run (a) Structural Reinforcing Steel. U-nencapsulated struc- in flexible metal condudt or an approved cable assembly tural reinforcing steel shall be bonded together by steel tie that includes an equipment grounding conductor within its wires or the equivalent. Where structural reinforcing steel is outer .sheath. The equipment grounding conductor shall encapsulated in a nonconductive compound, a copper con- cotnply with 250.24(A)(5). ductor grid shall be installed in accordance with 6$0.26(B)(1)(b). (B) Grounding. An equipment grounding conductor shall (b) Copper Conductor Grid A copper conductor grid be installed with the feeder conductors between the ground- shall be provided and shall comply with (b)(1) through ing terminal of the pool equipment panelboard and the (b)(4), grounding terminal of the applicable service equipment or (1) Be constructed of nvnimum 8 AWG bare solid copper source of a separately derived system. For other than (1) conductors bonded to each other at all points of crossing existing feeders covered in 680.25(A), Exception, or (2) (2) Conform to the contour of the pool and the pool deck feeders to separate buildings that do not utilize an insulated (3) Be arranged in, a 300-mm, (12-in.) by 300-mm (12-in.) equipment grounding conductor in accordance with network of conductors in a uniformly spaced perpen- 680.25(B)(2), this equipment grounding conductor shall be dicular grid pattern with a tolerance of 100 mm (4 in.) insulated. (4) Be. secured within or under the pool no more than (1) Size. This conductor shall be sized in accordance with 150 mm(6 in.)from the outer contour of the pool shell 250.122 but not smaller than 12 AWG. On separately de- (2) Perimeter Surfaces. The perimeter surface shall ex- rived systems, this conductor shall be sized in accordance tend for 1 in (3 ft) horizontally beyond the inside walls of with Table 250.66 but not smaller than 8 AWG. the pool and shall include unpaved surfaces as well as (2) Separate Buildings. A feeder to a separate building or Poured concrete and other types of paving. Bonding to pe- rimeter surfaces shall be provided as specified in structure shall be permitted to supply swimming pool 6$0.26(B)(2)(a) or (2)(b) and shall be attached to the pool equipment branch circuits, or feeders supplying swimming reinforcing steel or copper conductor grid at a minimum of pool equipment branch circuits, if the grounding arrange- four (4) points uniformly spaced around the perimeter of ments in the separate building meet the requirements in the pool. For nonconductive pool shells, bonding at four 250.32(B). Where installed in other than existing feeders points shall not be required. covered in 680.25(A), Exception, a separate equipment (a) Structural Reinforcing grounding conductor shall be an insulated conductor. .Steel. Structural reinforcing steel shall be bonded in accordance with 680.26($)(1)(a). 680.26 Equipotential Bonding. (b) Alternate Means. Where structural reinforcing steel is not available or is encapsulated in a nonconductive eom- (A) Performance. The equipotential bonding required by pound, a copper conductor(s) shall be utilized where the this section shall be installed to reduce voltage gradients in following requirements are met: the pool area. (1) At least one minimum 8 AWG bare solid copper con- ductor Shall be provided. (B) Bonded Parts. The parts specified in 680.26(B)(1) (2) The conductors shall follow the contour of the perim- through (B)(7) shall be bonded together using solid copper titer surface. conductors, insulated covered, or bare, not smaller than (3) Only listed splices shall be permitted. 8 AWG or with rigid metal conduit of brass or other iden- (4) The required conductor shall be 450 to 600 mm(18 to tified corrosion-resistant metal. Connections to bonded 24 in.) from the inside walls of the pool. parts shall be made in accordance with 250.8.An 8 AWG or (5) The required conductor shall be secured within or un- larger solid copper bonding conductor provided to reduce der the perimeter surface 100 mm to 150 mm (4 in. to voltage gradients in the pool area shall not be required to be 6 in.)below the subgrade. 70-566 NAMONAL ELECTRICAL CODE 2006 Edition ARTICLE 680—SWIMMING POOLS,FOUNTAINS,AND SIMILAR INSTALLATIONS 680.27 (3) Metallic Components. All metallic parts of the pool (C) Pool Water. An intentional bond of a minimum,con- structure, including reinforcing metal not addressed in ductive surface area of 5806 mmZ(9 in,Z)shall be installed 680.26(B)(1)(a),Shall be bonded.Where reinforcing steel is in contact with the pool water.This bond shall be permitted encapsulated with a nonconductive compound, the reinforc- to consist of parts that are required to be bonded in ing steel shall not be required to be bonded. 680.26(B). (4) Underwater Lighting. All metal forming shells and 680.27 Specialized Pool Equipment. mounting brackets of no-niche luminaires shall be bonded. Exception: Listed low-voltage lighting systems with non- (A) Underwater Audio Equipment.All underwater audio metallic forming shells shall not require bonding. equipment shall be identified for the purpose. (1) Speakers. Each speaker shall be mounted in an ap- (5) Metal Fittings. All metal fittings within or attached to proved metal forming shell, the front of which is enclosed the pool structure shall be bonded. Isolated parts that are by a captive metal screen, or equivalent, that is bonded to, not over 100 mm (4 in.) in any dimension and do not and secured to, the forming shell by a positive locking penetrate into the pool Structure more than 25 min: (1 in.) device that ensures a low-resistance contact and requires a shall not require bonding• tool to open for installation or servicing of the speaker.The (6) Electrical Equipment. Metal parts of electrical equip- forming shell shall be installed in a recess in the wall or ment associated with the pool water circulating system, floor of the pool. including pump motors and metal parts of equipment asso- (2) Wiring Methods. Rigid metal conduit of brass or other ciated with pool covers, including electric motors, shall be identified corrosion-resistant metal, liquidtight flexible non- bonded. metallic conduit (LFNC-B), rigid polyvinyl chloride con- Exception: Metal parts of listed equipment incorporating duit, or reinforced thermosetting resin conduit shall extend an approved system of double insulation shall not be from the forming shell to a listed junction box or other bonded. enclosure as provided in 680.24. Where rigid polyvinyl (a) Double Insulated Water Pump Motors. Where a chloride conduit,;reinforced thermosetting resin conduit, or double-insulated water pump motor is installed under the liquidtight flexible nonmetallic conduit is used, an 8 AWG provisions of this stile, a solid 8 AWG copper conductor of insulated solid or stranded copper bonding jumper shall be sufficient length to make a bonding connection to a replace- installed in this conduit. The bonding jumper shall be ter- ment motor shall be extended from the bonding grid to an minated in the forming shell and the junction box. The accessible point in the vicinity of the pool pump motor. termination of the 8 AWG bonding jumper in the forming Where there is no connection between the swimming pool shell shall be covered with, or encapsulated in, a listed bonding grid and the equipment grounding system for the potting compound to protect such connection from the pos- premises, this bonding conductor shall be connected to the sible deteriorating effect of pool water. equipment grounding conductor of the motor circuit. (3) Forming Shell and Metal Screen. The forming shell (b) Pool Water Heaters. For pool water heaters rated and metal screen shall be of brass or other approved at more than 50 amperes and having specific instructions corrosion-resistant metal. All forming shells shall include regarding bonding and grounding, only those parts desig- provisions for terminating an 8 AWG copper conductor. nated to be bonded shall be bonded and only those parts designated to be grounded shall be grounded. (B) Electrically Operated Pool Covers. (7) Metal Wiring Methods and Equipment. Metal- (1) Motors and Controllers. The electric motors, control- sheathed cables and raceways, metal piping, and all fixed lers, and wiring shall be located not less than 1.5 m (5 ft) metal parts shall be banded. from the inside wall of the pool unless separated from the Exception No. 1: Those separated from the pool by a per- pool by a wall, cover, or other permanent barrier, Electric manent barrier shall not be required to be banded motors installed below grade level shall be of the totally enclosed type. The device that controls the operation of the Exception No. 2: Those greater than 1.S m (S ft) horizon- motor for an electrically operated pool cover shall be lo- be b of the inside walls of the pool shall not be required to Gated such that the operator has full view of the pool. lie bonded. Exception No. 3: Those greater than 3.7 m (12 ft) mea- FPN No. I: For cabinets installed in damp and wet loca- sured vertically above the maximum water level of the pool, tions, see 312.2. or as measured vertically above any observation stands, FPN No. 2: For switches or circuit breakers installed in towers, or platforms, or any diving structures, shall not be wet locations, see 404.4. required to be bonded. FPM No. 3: For protection against liquids, see 430.11. 2008 Edition NATIONAL ELECTRICAL CODE 70-567 680.30 ARTICLE 680—SWIMMING POOLS,FOUNTAINS.AND SIMILAR INSTALLATIONS (2) Protection. The electric motor and controller shall be path the supply-cord of an appliance connected to the re- connected to a circuit protected by a ground-fault circuit ceptacle would follow without piercing a floor, wall, ceil- interrupter. ing, doorway with hinged or sliding door, window opening, (C) Deck Area Heating. The provisions of this section or other effective permanent barrier. shall apply to all pool deck areas, including a covered pool, FPN: For flexible cord usage, see 400.4. where electrically operated comfort heating units are in- stalled within 6.0 m (20 ft) of the inside wall of the pool. 680.33 Luminaires.An underwater luminaire, if installed, shall be installed in or on the wall of the storable pool. It (1) Unit Heaters. Unit heaters shall be rigidly mounted to shall comply with either 6$0.33(.4) or (B). the structure and shall be of the totally enclosed or guarded type. Unit heaters shall not be mounted over the pool or (A) 15 Volts or Less. A luminaire shall be part of a cord- within the area extending 1.5 m (5 ft) horizontally from the and-plug-connected lighting assembly. This assembly shall inside walls of a pool. be listed as an assembly for the purpose and have the fol- (2) Permanently Wired Radiant Heaters. Radiant elec- lowing construction features: tric heaters shall be suitably guarded and securely fastened (1) No exposed metal parts to their mounting device(s). Heaters shall not be installed (2) A luminaire lamp that operates at 15 volts or less over a pool or within the area extending 1.5 m (5 ft) hori- (3) An impact-resistant polymeric lens, luminaire body, zontally from the inside walls of the pool and shall be and transformer enclosure mounted at least 3.7 m (12 ft) vertically above the pool (4) A transformer meeting the requirements of 680.23(A)(2) deck unless otherwise approved, with a primary rating not over 150 volts (3) Radiant Heating Cables Not Permitted. Radiant (B) Over 15 Volts But Not over 150 Volts. A lighting heating cables embedded in or below the deck shall not be assembly without a transformer and with the luminaire permitted. lamp(s)operating at not over 150 volts shall be permitted to be cord-and-plug-connected where the assembly is listed as I1I. Storable Pools an assembly for the purpose. The installation shall comply with 680.23(A)(5), and the assembly shall have the follow- 680.30 General. Electrical installations at storable pools ing construction features: shall comply with the provisions of Part I and Part III of (1) No exposed metal parts this article. (2) An impact-resistant polymeric lens and luminaire body 680.31 Pumps. A cord-connected pool filter pump shall (3) A ground-fault circuit interrupter with open neutral incorporate an approved system of double insulation or its conductor protection as an integral part of the assembly equivalent and shall be provided with means for grounding (4) The luminaire lamp permanently connected to the ground- only the internal and nonaccessible non-current-carrying fault circuit interrupter with open-neutral protection metal parts of the appliance. (5) Compliance with the requirements of 680.23(A) The means for grounding shall be an equipment grounding conductor run with the power-supply conductors 680.34 Receptacle Locations.Receptacles shall not be lo- in the flexible cord that is properly terminated in a Bated Iess than 1.83 m(6 ft)from the inside walls of a pool. grounding-type attachment plug having a fixed grounding In determining these dimensions, the distance to be measured contact member, shall be the shortest path the supply cord of an appliance Cord-connected pool filter pumps shall be provided connected to the receptacle would follow without piercing a with a ground-fault circuit interrupter that is an integral part floor,wall, ceiling, doorway with hinged or sliding door,win- of the attachment plug or located in the power supply cord dow opening, or other effective permanent barrier. within 300 mm (12 in.) of the attachment plug. 680.32 Ground-Fault Circuit Interrupters Required. IV. Spas and Hot Tubs All electrical equipment, including power-supply cords, 680.40 General. Electrical installations at spas and hot used with storable pools shall be protected by ground-fault tubs shall comply with the provisions of Part I and Part IV circuit interrupters. of this article. All 125-volt receptacles located within 6.0 m (20 ft) of the inside walls of a storable pool shall be protected by a 680.41 Emergency Switch for Spas and Hot Tubs. A ground-fault circuit interrupter. In determining these di- clearly labeled emergency shutoff or control switch for the mensions, the distance to be measured shall be the shortest purpose of stopping the motor(s) that provide power to the 70-568 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 680—SWIMMING POOLS,FOUNTAINS,AND SIMILAR INSTALLATIONS 680.43 recirculation system and jet system shall be installed at a (1) Location. Receptacles shall be located at least 1.83 m point readily accessible to the users and not less than 1.5 m (6 ft)measured horizontally from the inside walls of the spa (5 ft) away, adjacent to, and within sight of the spa or hot or hot tub. tub. This requirement shall not apply to single-family dwellings. (2) Protection, General. Receptacles rated 125 volts and 30 amperes or less and located within 3.0 m (10 ft) of the 680.42 Outdoor Installations. A spa or hot tub installed inside walls of a spa or hot tub shall be protected by a outdoors shall comply with the provisions of Parts I and II ground-fault circuit interrupter. of this article, except as permitted in 680.42(A) and (B), (3) Protection, Spa or Hot Tbb Supply Receptacle. Re- that would otherwise apply to pools installed outdoors. ceptacles that provide power for a spa or hot tub shalt be (A) Flexible Connections. Listed packaged spa or hot tub ground-fault circuit-interrupter protected. equipment assemblies or self-contained spas or hot tubs (4) Measurements. In determining the dimensions in this utilizing a factory-installed or assembled control panel or section addressing receptacle spacings, the distance to be panelboard shall be permitted to use flexible connections as measured shall be the shortest path the supply cord of an covered in 680.42(A)(1) and (A)(2). appliance connected to the receptacle would follow without (1) Flexible Conduit. Liquidtight flexible metal conduit or Piercing a floor, wall, ceiling, doorway with hinged or sliding liquidtight flexible nonmetallic conduit shall be permitted door, window opening, or other effective permanent barrier. in lengths of not more than 1.8 m (6 ft). (B) Installation of Luminaires, Lighting Outlets, and (2) Cord-and-Plug Connections. Cord-and-plug connec- Ceiling-Suspended (Paddle) Fans. tions with a cord not longer than 4.6 m (15 ft) shall be per- (1) Elevation. Luminaires, except as covered in mitted where protected by a ground-fault circuit interrupter. 680.43(B)(2), lighting outlets, and ceiling-suspended (paddle) (B) Bonding. Bonding by metal-to-metal mounting on a fans located over the spa or hot tub or within 15 m(5 ft)from common frame or base shall be permitted. The metal bands the inside walls of the spa or hot tub shall comply with the or hoops used to secure wooden staves shall not be required clearances specified in (13)(1)(a), (13)(1)(b), and (13)(1)(c) to be bonded as required in 680.26. above the maximum water level. (a) Without GFCI. Where no GFCI protection is pro- (C) Interior Wiring to Outdoor Installations. In the in- vided, the mounting height shall be not less than 3.7 m terior of a one-family dwelling or in the interior of another (12 ft). building or structure associated with a one-family dwelling, (b) With GFCI. Where GFCI protection is provided, any of the wiring methods recognized in Chapter 3 of this the mounting height shall be permitted to be not less than Code that contain a copper equipment grounding conductor 2.3 m (7 ft 6 in.). that is insulated or enclosed within the outer sheath of the (c) Below 2.3 m (7 ft 6 in.). Luminaires meeting the wiring method and not smaller than 12 AWG shall be permit- requirements of item (1) or (2) and protected by a ground- ted to be used for the connection to motor,heating,and control fault circuit interrupter shall be permitted to be installed loads that are part of a self-contained spa or hot tub or a less than 2.3 m (7 ft 6 in.) over a spa or hot tub: packaged spa or hot tub equipment assembly. Wiring to an (1) Recessed luminaires with a glass or plastic lens, non- underwater luminaire shall comply with 680.23 or 680.33. metallic or electrically isolated metal trim, and suitable for use in damp locations 680.43 Indoor Installations. A spa or hot tub installed (2) Surface-mounted luminaires with a glass or plastic indoors shalt comply with the provisions of Parts I and 11 of globe, a nonmetallic body, or a metallic body isolated this article except as modified by this section and shall be from contact, and suitable for use in damp locations connected by the wiring methods of Chapter 3. (2) Underwater Applications. Underwater luminaires Exception: Listed spa and hot tub packaged units rated 20 shall comply with the provisions of 680.23 or 680.33. amperes or less shall be permitted to be cord-and-plug- connected to facilitate the removal or disconnection of the (C) Wall Switches. Switches shall be located at least 1.5 m unit far maintenance and repair. (5 ft), measured horizontally, from the inside walls of the spa or hot tub. (A) Receptacles. At least one 125-volt, 15- or 20-ampere receptacle on a general-purpose branch circuit shall be lo- (D) Bonding. The following parts shall he bonded together: cated not less than 1.83 rn (6 ft) from, and not exceeding (1) All metal fittings within or attached to the spa or hot 3.0 m (10 ft) from, the inside wall of the spa or hot tub. tub structure 2009 Edition NATIONAL ELECTRICAL CODE 70-569 680.44 ARTICLE 680—SWIMMING POOLS,FOUNTAINS,AND SIMILAR INSTALLATIONS (2) Metal parts of electrical equipment associated with the lights,controls,sanitizer generators,wiring,and so forth)shall spa or hot tub water circulating system, including pump be permitted without additional GFCI protection. motors (3) Metal raceway and metal piping that are within 1.5 m (B) Other Units. A field-assembled spa or hot tub rated 3 (5 ft) of the inside walls of the spa or hot tub and that phase or rated over 250 volts or with a heater load of more are not separated from the spa or hot tub by a perma- than 50 amperes shall not require the supply to be protected nent barrier by a ground-fault circuit interrupter. (4) All metal surfaces that are within 1.5 m (5 ft) of the (C) Combination Pool and Spa or Hot Tub. A combina- inside walls of the spa or hot tub and that are not tion pool/hot tub or spa assembly commonly bonded need separated from the spa or hot tub area by a permanent not be protected by a ground-fault circuit interrupter. barrier FPN: See 680.2 for definitions of seff-contained spa or hot Exception No. 1: Small conductive surfaces not likely to tub and for packaged spa or hot tub equipment assembly. become eneiSgized, such as air and water jets and drain fittings, where not connected to metallic piping, towel bars, V. Fountains mirror frames, and similar nonelectrical equipment, shall not be required to be bowled. 680.50 General.The provisions of Part I and Part V of this Exception No. 2: Metal parts of electrical equipment asso- article shall apply to all permanently installed fountains as ciated with the rater circulating system, including pump defined in 680.2. Fountains that have water common to a motors that are part of a listed self-contained spa or hot Pool shall additionally comply with the requirements in tub. Part II of this article. Part V does not cover self-contained, portable fountains. Portable fountains shall comply with (5) Electrical devices and controls that are not associated parts 11 and III of Article 422. with the spas or hot tubs and that are located not less than 1.5 m (5 ft) from such units; otherwise, they shall 680.51 Luminaires, Submersible Pumps, and Other be bonded to the spa or hot tub system Submersible Equipment. (E) Methods of Bonding. All metal parts associated with (A) Ground-Fault Circuit Interrupter. Luminaires, sub- the spa or hot tub shall be bonded by any of the following mersible pumps, and other submersible equipment, unless methods: listed for operation at 15 volts or less and supplied by a (1) The interconnection of threaded metal piping and fittings transformer that complies with 680.23(A)(2), shall be pro- (2) Metal-to-metal mounting on a common frame or base tected by a ground-fault circuit interrupter. (3) The provisions of a solid copper bonding jumper, insu- (B) Operating Voltage. No luminaires shall be installed laced, covered, or bare, not smaller than 8 AWG for operation on supply circuits over 150 volts between con- (F) Grounding.The following equipment shall be grounded: ductors.Submersible pumps and other submersible equipment (1) All electrical equipment located within 1.5 m (5 ft) of shall operate at 300 volts or less between conductors. the inside wall of the spa or hot tub (C) Luminaire Lenses. Luminaires shall be installed with (2) All electrical equipment associated with the circulating the top of the luminaire lens below the normal. water Ievel system of the spa or hot tub of the fountain unless listed for above-water locations. A luminaire facing upward shall comply with either(1)or(2): (G) Underwater Audio Equipment. Underwater audio (1) Have the lens adequately guarded to prevent contact by equipment shall comply with the provisions of Part 11 of any person this article. (2) Be listed for use without a guard 680.44 Protection. Except as otherwise provided in this (D) Overheating Protection.Electrical equipment that de- section, the outlet(s) that supplies a self-contained spa or pends on submersion for safe operation shall be protected hot tub, a packaged spa or hot tub equipment assembly, or against overheating by a low-water cutoff or other approved a fieId-assembled spa or hot tub shall be protected by a means when not submerged. ground-fault circuit interrupter. (E) Wiring. Equipment shall be equipped with provisions (A) Listed Units. If so marked, a listed self-contained unit for threaded conduit entries or be provided with a suitable or listed packaged equipment assembly that includes integral flexible cord.The maximum length of each exposed cord in ground-fault circuit-interrupter protection for all electrical the fountain shall be limited to 3.0 m (10 ft). Cords parts within the unit or assembly(pumps,air blowers,heaters, extending beyond the fountain perimeter shall be enclosed in 70-570 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 680—SWIMMING POOLS, FOUNTAINS,AND SIMILAR INSTALLATIONS 680.57 approved wiring enclosures. Metal parts of equipment in con- (3) Panelboards that are not part of the service equipment tact with water shall be of brass or other approved corrosion- and that supply any electrical equipment associated resistant metal. with the fountain (F) Servicing. All equipment shall be removable from the 680.55 Methods of Grounding. water for relamping or normal maintenance. Luminaires shall not be permanently embedded into the fountain struc- (A) Applied Provisions. The provisions of 680.21(A), ture such that the water level must be reduced or the foun- 680.23(B)(3), 680.23(F)(1) and (F)(2), 680.240, and tain drained for relamping, maintenance, or inspection. 680.25 shall apply. (G) Stability. Equipment shall be inherently stable or be (B) Supplied by a Flexible Cord. Electrical equipment securely fastened in place. that is supplied by a flexible cord shall have all exposed non—current-carrying metal parts grounded by an insulated 680.52 Junction Boxes and Other Enclosures. copper equipment grounding conductor that is an integral (A) General.Junction boxes and other enclosures used for part of this cord.The equipment grounding conductor shall be other than underwater installation shall comply with connected to an equipment grounding terminal in the supply 680.24. junction box, transformer enclosure, or other enclosure. (B) Underwater Junction Boxes and Other Underwater 680.56 Cord-and-Plug-Connected Equipment, Enclosures. Junction boxes and other underwater enclo- sures shall meet the requirements of 680.52(B)(1) and {A) Ground-Fault Circuit Interrupter. All electrical {B)(2) equipment, including power-supply cords, shall be pro- tected by ground-fault circuit interrupters. (1) Construction. (a) Underwater enclosures shall be equipped with pro- (B) Cord Type. Flexible cord immersed in or exposed to visions for threaded conduit entries or compression glands water shall be of a type for extra-hard usage, as designated or seals for cord entry. in Table 400.4, and shall be a listed type with a "W" suffix. (b) Underwater enclosures shall be submersible and made of copper, brass, or other approved corrosion-rests- (C) Sealing. The end of the flexible cord jacket and the flexible cord conductor termination within equipment shall tant material, be covered with,or encapsulated in,a suitable potting com- (2) Installation. Underwater enclosure installations shall pound to prevent the entry of water into the equipment comply with (a) and (b). through the cord or its conductors. In addition, the ground (a) Underwater enclosures shall be filled with an ap- connection within equipment shall be similarly treated to proved potting compound to prevent the entry of moisture. protect such connections from the deteriorating effect of (b) Underwater enclosures shall be firmly attached to water that may enter into the equipment. the supports or directly to the fountain surface and bonded as required.Where the junction box is supported only by con- (D} Terminations. Connections with flexible card shall be dolts in accordance with 31;4.23(E)and(k"),the conduits shall permanent, except that grounding-type attachment plugs be of copper, brass, stainless steel, or other approved cor- and receptacles shall be permitted to Facilitate removal or rosion-resistant metal. Where the box is fed by nonmetallic disconnection For maintenance,repair,or storage of fixed or conduit, it shall have additional supports and fasteners of cop- part equipment not located in any water-containing per, brass, or other approved corrosion-resistant material. P of a fountain. • 680.53 Bonding. All metal piping systems associated with 680.57 Signs. the fountain shall be bonded to the equipment grounding (A) General. This section covers electric signs installed conductor of the branch circuit supplying the fountain. within a fountain or within 3.0 m(10 ft)of the fountain edge. FPN: See 250.122 for sizing of these conductors. (B) Ground-Fault Circuit-Interrupter Protection for 68054 Grounding. The following equipment shall be Personnel. All circuits supplying the sign shall have grounded: ground-fault circuit-interrupter protection for personnel. (1) All electrical equipment located within the fountain or (C) Location. within 1.5 m (5 ft) of the inside wall of the fountain (2) All electrical equipment associated with the recirculat- (1) Fixed or Stationary.A fixed or stationary electric sign ing system of the fountain installed within a fountain shall be not less than 1.5 m(5 ft) 2008 Edition NATIONAL ELECTRICAL CODE 70-571 680.58 ARTICLE.680--SWIMMING POOLS,FOUNTAINS,AND SIMILAR INSTALLATIONS inside the fountain measured from the outside edges of the lights,controls,Sanitizer generators, wiring, and so forth)shall fountain. be permitted without additional GFCI protection. (2) Portable. A portable electric sign shall not be placed (2) Other Units. A therapeutic tub or hydrotherapeutic within a pool or fountain or within 1.5 m (5 ft) measured tank rated 3 phase or rated over 250 volts or with a heater horizontally from the inside walls of the fountain, load of more than 50 amperes shall not require the supply to be protected by a ground-fault circuit interrupter. (D) Disconnect. A sign shall have a local disconnecting (B) Bonding.The following parts shall be bonded together: means in accordance with 600.6 and 680.12. (1) All metal fittings within or attached to the tub structure (E) Bonding and Grounding. A sign shall be grounded (2) Metal parts of electrical equipment associated with the and bonded in accordance with 600.7. tub water circulating system, including pump motors (3) Metal-sheathed cables and raceways and metal piping 680.58 GFCI Protection for Adjacent Receptacle Out- that are within 15 m (5 ft)of the inside walls of the tub lets. All 15- or 20-ampere, single-phase 125-volt through and not separated from the tub by a permanent barrier 250-volt receptacles located within 6.0 m (20 ft) of a foun- (4) All metal surfaces that are within 1.5 m (5 ft) of the tain edge shall be provided with GFCI protection. inside walls of the tub and not separated from the tub area by a permanent barrier VI. Pools and Tubs for Therapeutic Use (5) Electrical devices and controls that are not associated with the therapeutic tubs and located within 1.5 m(5 ft) 680.60 General. The provisions of Part I and Part VI of from such units. this article shall apply to pools and tubs for therapeutic use in health care Facilities, gymnasiums, athletic training (C) Methods of Bonding. All metal parts required to be bonded by this section shall be bonded by any of the fol- rooms, and similar areas. Portable therapeutic appliances lowing methods: shall comply with Parts II and III of Article 422. (1) The interconnection of threaded metal piping and fittings FPN: See 517.2 for definition or health care facilities. (2) Metal-to-metal mounting on a common frame or base (3) Connections by suitable metal clamps 680.61 Permanently Installed Therapeutic Pools.Thera- {4) By the provisions of a solid capper bonding jumper, peutic pools that are constructed in the ground, on the insulated, covered, or bare, not smaller than S AWG ground, or in a building in such a manner that the pool cannot be readily disassembled shall comply with Parts I (D) Grounding. and II of this article. (1) Fixed or Stationary Equipment. The equipment speci- Exception: The limitations of 680.22(C)(1) through (C)(4) fied in (a) and (b) shall be connected to the equipment shall not apply where all luminaires are of the totally en- grounding conductor. closed npe. (a) Location. All electrical equipment located within 1.5 m (5 ft) of the inside wall of the tub shall be connected 680.62 Therapeutic Tubs (Hydrotherapeutic Tanks). to the equipment grounding conductor. Therapeutic tubs, used for the submersion and treatment of (b) Circulation System.All electrical equipment associ- patients, that are not easily moved from one place to an- ated with the circulating system of the tub shall be con- other in normal use or that are fastened or otherwise se- nected to the equipment grounding conductor. cured at a specific location, including associated piping sys- (2) Portable Equipment. Portable therapeutic appliances tems, shall conform to Part V1, shall meet the grounding requirements in 250.114. (A) Protection. Except as otherwise provided in this sec- (E) Receptacles. All receptacles within 1.83 nn (6 ft) of a therapeutic tub shall be protected by a ground-fault circuit tion, the outlet(s) that supplies aself-contained therapeutic interrupter. tub or hydrotherapeutic tank, a packaged therapeutic tub or hydrotherapeutic tank, or a field-assembled therapeutic tub (F) Luminaires. All luminaires used in therapeutic tub ar- or hydrotherapeutic tank shall be protected by a ground- eas shall be of the totally enclosed type. fault circuit interrupter. (I) Listed Units. If so marked, a listed self-contained unit VII. Hydromassage Bathtubs or listed packaged equipment assembly that includes integral 680.70 General. Hydromassage bathtubs as defined in ground-fault circuit-interrupter protection for all electrical 680.2 shall comply with Part VII of this article. They shall parts within the unit or assembly(pumps, air blowers,heaters, not be required to comply with other parts of this article. 70-572 NATIONAL ELECTRICAL CQnE 2008 Edition ARTICLE 682—NATURAL AND ARTIFICIALLY MADE BODIES OF WATER 682.10 680.71 Protection. Hydromassage bathtubs and their asso- ponds, fish farm ponds, storm retention basins, treatment ciated electrical components shall be on an individual ponds, and irrigation (channel) facilities.Water depths may branch circuit(s) and protected by a readily accessible vary seasonally or be controlled, ground-fault circuit interrupter. All 125-volt, single-phase receptacles not exceeding 30 amperes and located within Electrical Datum Plane. The electrical datum plane as 1.83 m(6 ft) measured horizontally of the inside walls of a used in this article is defined as follows: hydromassage tub shall he protected by a ground-fault cir- (1) In land areas subject to tidal fluctuation, the electrical cuit interrupter, datum plane is a horizontal plane 600 mm (2 ft) above the highest tide level for the area occurring under nor- 680.72 Other Electrical Equipment.Luminaires, switches, mal circumstances, that is, highest high tide. receptacles, and other electrical equipment located in the (2) In land areas not subject to tidal fluctuation, the elec- same room, and not directly associated with a hydromas- trical datum plane is a horizontal plane 600 mm (2 ft) sage bathtub, shall be installed in accordance with the re- above the highest water level for the area occurring quirements of Chapters I through 4 in this Code covering under normal circumstances. the installation of that equipment in bathrooms. (3) In land areas subject to flooding, the electrical datum plane based on (1) or (2) above is a horizontal plane 680.73 Accessibility. Hydromassage bathtub electrical 600 mm (2 ft) above the point identified as the prevail- equipment shall be accessible without damaging the build- ing high water mark or an equivalent benchmark based ing structure or building finish. on seasonal or storm-driven flooding from the authority having jurisdiction. 680.74 Bonding. All metal piping systems and all grounded (4) The electrical datum plane for floating structures and metal parts in contact with the circulating water shall be landing stages that are (1) installed to permit rise and bonded together using a solid copper bonding jumper, insu- fail response to water level, without lateral movement, lated,covered,or bare,not smaller than 8 AWG.The bonding and (2) that are so equipped that they can rise to the jumper shall be connected to the terminal on the circulating datum plane established for (1) or (2) above, is a hori- pump motor that is intended for this purpose. The bonding zontal plane 750 mm (30 in.) above the water level at jumper Shall not be required to be connected to a double in- the floating structure or landing stage and a minimum sulated circulating pump motor. The 8 AWG or larger solid of 300 mm (12 in.) above the level of the deck. copper bonding jumper Shall be required for equipotential bonding in the area of the hydrornassage bathtub and shall not Equrpotential Plane. An area where wire mesh or other be required to be extended or attached to any remote panel- Conductive elements are on, embedded in, or placed under board,service equipment, or any electrode. the walk surface within 75 mm (3 in.), bonded to all metal structures and fixed nonelectrical equipment that may be- come energized, and connected to the electrical grounding system to prevent a difference in voltage from developing within the plane. ARTICLE 682 Natural Bodies of Water. Bodies of water such as lakes, Natural and Artificially Made streams, ponds, rivers, and other naturally occurring bodies Bodies of Water of water, which may vary in depth throughout the year. Shoreline. The farthest extent of standing water under the I. General applicable conditions that determine the electrical datum 682.1 Scope.This article applies to the installation of elec- plane for the specified body of water. trical wiring for, and equipment in and adjacent to, natural 682.3 Other Articles.Wiring and equipment in or adjacent or artificially made bodies of water not covered by other to natural or artificially made bodies of water shall comply articles in this Code, such as but not limited to aeration with the applicable provisions of other articles of this Code, ponds, fish farm ponds, storm retention basins, treatment except as modified by this article. If the water is subject to ponds, irrigation (channels) facilities, boat traffic, the wiring shall comply with 555.13(B). 682.2 Definitions. 11. Installation Artificially Made Bodies of Water. Bodies of water that have been constructed or modified to fit some decorative or 682.10 Electrical Equipment and Transformers.Electri- commercial purpose such as, but not limited to, aeration cal equipment and transformers, including their enclosures, 2008 Edition NATIONAL ELECTRICAL CODE 70-573 682.11 ARTICLE 682—NATURAL AND ARTIFICIALLY MADE BODIES OF WATER shall be specifically approved for the intended location. No 1II. Grounding and Bonding portion of an enclosure for electrical equipment not identi- 682.30 Grounding. Wiring and equipment within the fied for operation while submerged shall be located below scope of this article shall be grounded as specified in Part the electrical datum plane. III of 553, 555.15, and with the requirements in Part III of 682.11 Location of Service Equipment. On land, the ser- this article. vice equipment for floating structures and submersible elec- trical equipment shall be located no closer than 1.5 m(5 ft) 682.31 Equipment Grounding Conductors. horizontally from the shoreline and live parts shall be el- (A) Type. Equipment grounding conductors shall be insu- evated a minimum of 300 mm (12 in.) above the electrical lated copper conductors sized in accordance with 250.122 datum plane. Service equipment shall disconnect when the but not smaller than 12 AWG. water level reaches the height of the established electrical datum plane. (B) Feeders.Where a feeder supplies a remote panelboard, an insulated equipment grounding conductor shall extend 682.12 Electrical Connections. All electrical connections from a grounding terminal in the service to a grounding not intended for operation while submerged shall be located terminal and busbar in the remote panelboard. at ]east 300 mm (]2 in.) above the deck of a floating or fixed structure, but not below the electrical datum plane. (C) Branch Circuits. The insulated equipment grounding conductor for branch circuits shall terminate at a grounding 682.13 Wiring Methods and Installation. Liquidtight terminal in a remote panelboard or the grounding terminal flexible metal Conduit or Iiquidtight flexible nonmetallic in the main service equipment. conduit with approved fittings shall be permitted for feeders and where flexible connections are required for services. (D) Cord-and-Plug-Connected Where ground- and usage portable power cable listed for both wet ed, cord-and-plug-connected appliances shall be grounded Iacations and sunlight resistance shall be permitted fora by means of an equipment grounding conductor in the cord feeder or a branch circuit where flexibility is required. and agrounding-type attachment plug. Other wiring methods Suitable for the location shall be per- 682.32 Bonding of Non-Current-Carrying Metal Parts. mitted to be installed where flexibility is not required.Tem- All metal parts in contact with the water, all metal piping, porary wiring in accordance with 590.4 shall be,permitted. tanks, and all non-current-carrying meta] parts that may 682.14 Disconnecting Means for Floating Structures or become energized shall be bonded to the grounding bus in Submersible Electrical Equipment. the panelboard. (A) Type. The disconnecting means shall be permitted to 682.33 Equipotential Planes and Bonding of Equipoten- consist of a circuit breaker, switch, or both that simulta- tial Planes. An equipotential plane shall be installed where neously opens all ungrounded circuit conductors, and shall required in this section to mitigate step and touch voltages be properly identified as to which structure or equipment it at electrical equipment. controls. (B) Location. The disconnecting means shall be readily (A) Areas Requiring Equipotential Planes. Equipotential planes shall be installed adjacent to all outdoor service accessible on land and shall be located in the supply circuit equipment or disconnecting means that control equipment ahead of the structure or equipment connection. The dis- connecting means shall be within sight of, but not closer in or on water, that have a metallic enclosure and controls accessible to personnel, and that are likely to become ener- than 1.5 m (5 ft) horizontally from, the edge of the share- gized. The equipotential plane shall encompass the area line and live parts elevated a minimum of 300 m (12 in.) around the equipment and shall extend from the area di- rectly below the equipment out not less than 900 rnm 682.15 Ground-Fault Circuit-Interrupter (GFCI) Pro- (36 in.) in all directions from which a person would be able tection. Fifteen- and 20-ampere single-phase, 125-volt to stand and come in contact with the equipment. through 250-volt receptacles installed outdoors and in or on (B) Areas Not Requiring Equipotential Planes. Equipo- floating buildings or structures within the electrical datum tential planes shall not be required for the controlled equip- plane area that are used for storage, maintenance, or repair ment supplied by the service equipment or disconnecting where portable electric hand tools, electrical diagnostic means. All circuits rated not more than 60 amperes at 120 equipment, or portable lighting equipment are to be used through 250 volts, single phase, shall have GFCI protection. shall be provided with GFCI protection. The GFCI protec- tion device shall be located not less than 300 mm (12 in.) (C) Bonding. Equipotential planes shall be bonded to the above the established electrical datum plane. electrical grounding system. The bonding conductor shall 70-574 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 690--SOLAR PHOTOVOLTAIC SYSTEMS 690.2 be solid copper, insulated, covered or bare, and not smaller Table 685.3 Application of Other Articles than 8 AWG. Connections shall be made by exothermic welding or by listed pressure connectors or clamps that are Conductor/Equipment Section labeled as being suitable for the purpose and are of stainless steel, brass, copper, or copper alloy. More than one building or other 225, Part II structure Ground-fault protection of 230.95, Exception equipment Protection of conductors 240.4 Electrical system coordination 240.12 ARTICLE 685 Ground-fault protection of 240.13(1) equipment Integrated Electrical Systems Grounding ac systems of 50 volts 250.21 to 1000 volts Equipment protection 427.22 I. General Orderly shutdown 430.44 Disconnection 430.74, Exception Nos, 1 685.1 Scope. This article covers integrated electrical sys- and 2 tems,other than unit equipment, in which orderly shutdown Disconnecting means in sight 430.102(A), Exception No. 2 is necessary to ensure safe operation.An integrated efectri- from controller stern as used in this article is a unitized segment of an Energy from more than one 430.113, Exception Nos. 1 cal s Y g source and 2 industrial wiring system where all of the following condi- Disconnecting means 645.10, Exception tions are met: Uninterruptible power supplies 645.11(1) (1) An orderly shutdown is required to minimize personnel (UPS) hazard and equipment damage. Point of connection 705.12(A) (2) The conditions of maintenance and supervision ensure that qualified persons service the system. The name(s) 685.14 Ungrounded Control Circuits. Where operational of the qualified person(s) shall be kept in a permanent continuity is required, control circuits of 150 volts or less record at the office of the establishment in charge of the from separately derived systems shall be permitted to be completed installation. ungrounded. A person designated as a qualified person shall pos- sess the skills and knowledge related to the construc- tion and operation of the electrical equipment and in- stallation and shall have received documented safety ARTICLE 690 training on the hazards involved. Documentation of their qualifications shall be on file with the office of the Solar Photovoltaic Systems establishment in charge of the completed installation. (3) Effective safeguards acceptable to the authority having I. General jurisdiction are established and maintained. 690.1 Scope. The provisions of this article apply to solar 685.3 Application of Other Articles.The articles/sections photovoltaic electrical energy systems, including the array circuit(s), inverter(s), and controller(s) for such systems. in Table 685.3 apply to particular cases of installation of [See Figure 690.1(A) and Figure 690.1(B).] Solar photovol- conductors and equipment, where there are orderly shut- talc systems covered by this article may be interactive with down requirements that are in addition to those of this other electrical power production sources or stand-alone, article or are modifications of them. with or without electrical energy storage such as batteries. These systems may have ac or do output for utilization. II. Orderly Shutdown 690.2 Definitions. 685.10 Location of Overcurrent Devices in or on Pre- mises. Location of overctrrrent devices that are critical to Alternating-Current (ac) Module (Alternating-Current integrated electrical systems shall be permitted to be asses- Photovoltaic Module). A complete, environmentally ero- sible, with mounting heights permitted to ensure security tested unit consisting of solar cells, optics, inverter, and from operation by unqualified personnel. other components, exclusive of tracker, designed to gener- ate ac power when exposed to sunlight. 685.12 Direct-Current System Grounding, Two-wire do Array. A mechanically integrated assembly of modules or circuits shall be permitted to be ungrounded. panels with a support structure and foundation, tracker, and 2008 Edition NATIONAL ELECTRICAL CODE 70-575 690.2 ARTICLE 690—SOLAR PHOTOVOLTAIC SYSTEMS Photovoltaic source circuits Photovoltaic source circuits Inverter input circuit Photovoltaic / Inverter output circuit 4—Blocking diodes output circuit Electric production and distribution Fuses Photovoltaic output circuit network connection Inverter Interactive s stem O Solar cells � �O Wind,engine-generator, r7 micro-hydro-electric,and Energy storage,charge controller, other power sources and system control Inverter input circuit Module / Inverter output circuit Photovoltaic Panel output circuit Hy brid system do loads Inverter Array or photovoltaic a controller Char power source g Photovoltaic output Inverter input circuit circuit / Inverter output circuit Dedicated branch circuit IG/ Main supply of the electric production equipment for and distribution network Inverter ac loads Inverter output circuit Main supply equipment for do loads ac module(includes inverter) �E Stand-alone s stem nergy storage Array(of ac modules} ac modules stem Notes. 1. These diagrams are intended to be a means of identification for Notes: photovoltaic system components,circuits,and connections. 1. These diagrams are intended to be a means of identification for 2. Disconnecting means and overcurrent protection required by photovoltaic system components,circuits,and connections. Article 690 are not shown. 2. Disconnecting means required by Article 690,Part III,are not shown. 3. System grounding and equipment grounding are not shown. 3. System grounding and equipment grounding are not shown. See Article 690,Part V. See Article 690,Part V. 4. Custom designs occur in each configuration,and some components are optional. Figure 690.1(A) Identification of Solar Photovoltaic System Figure 690.1(B) Identification of Solar Photovoltaic System Components. Components in Common System Configurations. other components, as required, to form a direct-current as a utility system and connected loads, that is external to power-producing unit, and not controlled by the photovoltaic power system. Bipolar Photovoltaic Array. A photovoltaic array that has Hybrid System. A system comprised of multiple power two outputs, each having opposite polarity to a common sources. These power sources may include photovoltaic, reference point or center tap. wind, micro-hydro generators, engine-driven generators, Blocking Diode. A diode used to block reverse flow of and others, but do not include electrical production and current into a photovoltaic source circuit. distribution network systems. Energy storage systems, such as batteries, do not constitute a power source for the pur- Building Integrated Photovoltaics.Photovoltaic cells, de- pose of this definition. vices, modules, or modular materials that are integrated into the outer surface or structure of a building and serve as Interactive System.A solar photovoltaic system that oper- the outer protective surface of that building. ates in parallel with and may deliver power to an electrical production and distribution network.For the purpose of this Charge Controller. Equipment that controls do voltage or definition, an energy storage subsystem of a solar photovol- taic system, such as a battery, is not another electrical pro- Diversion Charge Controller. Equipment that regulates duction source. the charging process of a battery by diverting power from Inverter.Equipment that is used to change voltage level or energy storage to direct-current or alternating-current loads waveform, or both, of electrical energy. Commonly, an in- or to an interconnected utility service. verter [also known as a power conditioning unit (PCU) or Electrical Production and Distribution Network. A power conversion system (PCS)l is a device that changes power production,distribution, and utilization system, such do input to an ac output. Inverters may also function as 70-576 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 690—SOLAR PHOTOVOLTAIC SYST$MS 696.5 battery chargers that use alternating current from another 690.4 Installation. source and convert it into direct current for charging batteries. (A) Solar Photovoltaic System. A solar photovoltaic sys- Inverter Input Circuit. Conductors between the inverter tem shall be permitted to supply a building or other struc- and the battery in stand-alone systems or the conductors ture in addition to any service(s) of another electricity sup- between the inverter and the photovoltaic output circuits for ply system(s). electrical production and distribution network. (B) Conductors of Different Systems. Photovoltaic Inverter Output Circuit. Conductors between the inverter source circuits and photovoltaic output circuits shall not be and an ac panelboard for stand-alone systems or the con- contained in the same raceway, cable tray,cable,outlet box, ductors between the inverter and the service equipment or junction box, or similar fitting as feeders or branch circuits another electric power production source, such as a utility, of other systems, unless the conductors of the different sys- for electrical production and distribution network. tems are separated by a partition or are connected together. Module. A complete, environmentally protected unit con- (C) Module Connection Arrangement. The connections sisting of solar cells, optics, and other components, exclu- to a module or panel shall be arranged so that removal of a sive of tracker, designed to generate do power when ex- module or panel from a photovoltaic source circuit does not posed to sunlight. interrupt a grounded conductor to another photovoltaic source circuit. Sets of modules interconnected as systems Panel. A collection of modules mechanically fastened to- gether, wired, and designed to provide afield-installable unit. rated at SO volts or less, with or without blocking diodes,and having a single overcurrent device shall be considered Photovoltaic Output Circuit. Circuit conductors between as a single-source circuit. Supplementary overcurrent de- the photovoltaic source circuit(s) and the inverter or do vices used for the exclusive protection of the photovoltaic utilization equipment. modules are not considered as overcurrent devices for the purpose of this section. Photovoltaic Power Source. An array or aggregate of ar- rays that generates do power at system voltage and current. (D) Equipment. Inverters, motor generators, photovoltaic modules, photovoltaic panels, ac photovoltaic modules, Photovoltaic Source Circuit. Circuits between modules source-circuit combiners, and charge controllers intended and from modules to the common connection point(s) of for use in photovoltaic power systems shall be identified the do system. and listed for the apphieation. Photovoltaic System Voltage.The direct current (dc) volt- age of any photovoltaic source or photovoltaic output cir- cuit. For multiwire installations, the photovoltaic system taic arrays shall be provided with do ground-fault protec-- voltage is the highest voltage between any two do conduc- tion meeting the requirements of 690.5(A) through (C) to tors. reduce fire hazards. Ungrounded do photovoltaic arrays shall comply with 690.35. Solar Cell. The basic photovoltaic device that generates electricity when exposed to light. Exception No. 1: Ground-mounted or pole-mounted photo- voltaic arrays with not more than two ,paralleled source Solar Photovoltaic System.The total components and sub- circuits and with all de source and do output circuits iso- systems that, in combination, convert solar energy into lated from buildings shall be permitted without ground- electric energy suitable for connection to a utilization load. fault protection. Stand-Alone System.A solar photovoltaic system that sup- Exception No. 2: PV arrays installed at other than dwell- plies power independently of an electrical production and ing units Shall be permitted without ground fault protection distribution network. where the equipment grounding conductors are sized in accordance with 690.45. 690.3 Other Articles. Wherever the requirements of other articles of this Code and Article 690 differ,the requirements (A) Ground-Fault Detection and Interruption. The of Article 690 shall apply and, if the system is operated in ground-fault protection device or system shall be capable of parallel with a primary source(s) of electricity, the require- detecting aground-fault current, interrupting the flow of menu in 705.14, 705.16, 705.32, and 705.143 shall apply. fault current, and providing an indication of the fault. Automatically opening the grounded conductor of the Exception: Solar photovoltaic systems, equipment, or wiring faulted circuit to interrupt the ground-fault current path installed in a hazardous(classified)location shall also comply shall be permitted. If a grounded Conductor is opened to with the applicable portions of Articles 500 through 516 interrupt the ground-fault current path,all conductors of the 2008 Edition NATIONAL ELECTRICAL CODE 70...577 690.6 ARTICLE 690 SOLAR PHOTOVOLTAIC SYSTEMS faulted circuit shall be automatically and simultaneously II. Circuit Requirements opened. 690.7 Maximum Voltage. Manual operation of the main PV do disconnect shall not activate the ground-fault protection device or result in (A) Maximum Photovoltaic System Voltage.In a do pho- grounded conductors becoming ungrounded. tovoltaic source circuit or output circuit, the maximum pho- tovoltaic system voltage for that circuit shall be calculated (B) Isolating Faulted Circuits. The faulted circuits shall as the sum of the rated open-circuit voltage of the series- be isolated by one of the two following methods: connected photovoltaic modules corrected for the lowest (1) The ungrounded conductors of the faulted circuit shall expected ambient temperature. For crystalline and multic- be automatically disconnected. rystalline silicon modules, the rated open-circuit voltage (2) The inverter or charge controller fed by the faulted shall be multiplied by the correction factor provided in circuit shall automatically cease to Supply power to Table 690.7. This voltage shall be used to determine the voltage rating of cables, disconnects, overcurrent devices, output circuits. and other equipment. Where the lowest expected ambient (C) Labels and Markings. A warning label shall appear temperature is below —40°C (-40°F), or where other than on the utility-interactive inverter or be applied by the in- crystalline or multicrystalline silicon photovoltaic modules stabler near the ground-fault indicator at a visible location, are used, the system voltage adjustment shall be made in stating the following: accordance with the manufacturer's instructions. When open-circuit voltage temperature coefficients are WARNING supplied in the instructions for listed PV modules, they ELECTRIC SHOCK HAZARD shall be used to calculate the maximum photovoltaic sys- IF A GROUND FAULT IS INDICATED, tem voltage as required by 110.3(B) instead of using Table NORMALLY GROUNDED CONDUCTORS 690.7• MAY BE UNGROUNDED AND ENERGIZED Table 690.7 Voltage Correction Factors for Crystalline and When the photovoltaic system also has batteries, the l Multicrystalline Silicon Modules same warning shall also be applied by the installer in a visible location at the batteries. Correction Factors for Ambient Temperatures Below 25°C (77°F). (Multiply the rated open circuit voltage by the 690.6 Alternating-Current (ac) Modules. appropriate correction factor shown below.) Ambient Ambient (A) Photovoltaic Source Circuits. The requirements of Temperature CC) Factor Temperature CF) Article 690 pertaining to photovoltaic source circuits shall not apply to ae modules. The photovoltaic source circuit, 24 to 20 1.02 76 to 68 conductors, and inverters shall be considered as internal 19 to 15 1.04 67 to 59 14 to 10 1.06 58 to 50 wiring of an ac module. 9 to 5 1.08 49 to 41 4to0 1.10 40 to 32 (B) Inverter Output Circuit. The output of an ac module -1 to-5 t.12 31 to 23 shall be considered an inverter output circuit. -6 to-10 L14 22 to 14 -11 to-15 1.16 13to5 (C) Disconnecting Means. A single disconnecting means, -16 to-20 1.18 4 to-4 in accordance with 690.15 and 690.17, shall be permitted -21 to-25 1.20 -5 to-13 --26 to--30 1.21 -14 to-22 for the combined ac output of one or more ac modules. -31 to-35 1.23 -23 to-31 Additionally, each ac module in a multiple ac module sys- -36 to-40 1.25 -32 to-40 tem shall be provided with a connector,bolted, or terminal- type disconnecting means. (B) Direct-Current Utilization Circuits. The voltage of (D) Ground-Fault Detection. Alternating-current module do utilization circuits shall conform to 210.6. systems shall be permitted to use a single detection device (C) Photovoltaic Source and Output Circuits. In one- to detect only ac ground faults and to disable the array by and two-family dwellings, photovoltaic source circuits and removing ac power to the ac module(s). photovoltaic output circuits that do not include lamphold- ers, fixtures, or receptacles shall be permitted to have a (E) Overcurrent Protection. The output circuits of ac maximum photovoltaic system voltage up to 600 volts. modules shall be permitted to have overcurrent protection Other installations with a maximum photovoltaic system and conductor sizing in accordance with 240.5(B)(2). voltage over 600 volts shall comply with Article 690, Part I. 70-578 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 690—SOLAR PHOTOVOLTAIC SYSTEMS 690.9 (D) Circuits over 150 Volts to Ground. In one- and two- Exception: Circuits containing an assembly, together with family dwellings, live parts in photovoltaic source circuits its overcurrent device(s), that is listed for continuous op- and photovoltaic output circuits over 150 volts to ground eration at 100 percent of its rating shall be permitted to be shall not be accessible to other than qualified persons while utilized at 100 percent of its rating. energized. (2) Internal Current Limitation. Overcurrent protection FPN: See 110.27 for guarding of live parts, and 210.6 for for photovoltaic output circuits with devices that internally voltage to ground and between conductors. limit the current from the photovoltaic output circuit shall (E) Bipolar Source and Output Circuits. For 2-wire cir- be permitted to be rated at less than the value calculated in suits connected to bipolar systems, the maximum system 690.8(B)(1). This reduced rating shall be at least 125 per- voltage shall be the highest voltage between the conductors cent of the limited current value. Photovoltaic output circuit of the 2-wire circuit if all of the following conditions apply: conductors shall be sized in accordance with 690.8(B)(1). (t) One conductor of each circuit is solidly grounded. Exception: An overcurrent device in an assembly listed for (2) Each circuit is connected to a separate subarray. continuous operation at 100 percent of its rating shall be (3) The equipment is clearly marked with a label as permitted to be utilized at 100 percent of its rating. follows: (C) Systems with Multiple Direct-Current Voltages.For WARNING a photovoltaic power source that has multiple output circuit BIPOLAR PHOTOVOLTAIC ARRAY, voltages and employs a common-return conductor, the am- DISCONNECTION OF NEUTRAL pacity of the common-return conductor shall not be less OR GROUNDED CONDUCTORS than the sum of the ampere ratings of the overcurrent de- MAY RESULT IN OVERVOLTAGE vices of the individual output circuits. ON ARRAY OR INVERTER. (D) Sizing of Module Interconnection Conductors. 690.8 Circuit Sizing and Current. Where a single overcurrent device is used to protect a set of (A) Calculation of Maximum Circuit Current. The two or more parallel-connected module circuits, the ampac- maximum current for the specific circuit shall be calculated ity of each of the module interconnection conductors shall in accordance with 690.8(A)(1) through (A)(4), not be less than the sum of the rating of the single fuse plus 125 percent of the short-circuit current from the other FPN: Where: the requirements of 690.8(A)(1) and (B)(1) parallel-connected modules. are both applied, the resulting multiplication factor is 156 percent. 690.9 Overcurrent Protection. (1) Photovoltaic Source Circuit Currents.The maximum current shall be the sum of parallel module rated short- (A) Circuits and Equipment. Photovoltaic source circuit, circuit currents multiplied by 125 percent. photovoltaic output circuit, inverter output circuit, and stor- age battery circuit conductors and equipment shall be pro- (2) Photovoltaic Output Circuit Currents. The maxi- tested in accordance with the requirements of Article 240. mum current shall be the sum of parallel source circuit Circuits connected to more than one electrical source shall maximum currents as calculated in 690.8{A}(1). have overcurrent devices located so as to provide overcur- (3) Inverter Output Circuit Current.The maximum cur- rent protection from all sources. rent shall be the inverter continuous output current rating. Exception: An overcurrent device shall not be required for (4) Stand-Alone Inverter Input Circuit Current. The circuit conductors sized in accordance with 690.8(6) and maximum current shall be the stand-alone continuous in- located where one of the following apply: verter input current rating when the inverter is producing (a) There are no external sources such as parallel- rated power at the lowest input voltage. connected source circuits, batteries, or backfeed from in- (B) Ampacity and Overcurrent Device Ratings.Photovol- verters. taic system currents shall be considered to be continuous. (b) The short-circuit currents frown all sources do not exceed the ampac•ity of the conductors. (1) Sizing of Conductors and Overcurrent Devices. The circuit conductors and overcurrent devices shall be sized to FPN: Possible backfeed of current from any source of sup- ply, including a supply through an inverter into the photo- carry not less than 125 percent of the maximum currents voltaic output circuit and photovoltaic source circuits, is a as calculated in 690.8(A). The rating or setting of over- consideration in determining whether adequate overcurrent current devices shall be permitted in accordance with protection from all sources is provided for conductors and 240.4(B) and (C). modules. 2008 Edition NATIONAL ELECTRICAL CODE 70-579 690.10 ARTICLE 690—SOLAR PHOTOVOLTAIC SYSTEMS (B) Power Transformers. Overcurrent protection for a overcurrents in accordance with Article 240. The overcur- transformer with a source(s) on each side shall be provided rent protection shall be located at the output of the inverter. in accordance with 450.3 by considering first one side of the transformer, then the other side of the transformer, as (C) Single 120-Volt Supply. The inverter output of a the primary. stand-alone solar photovoltaic system shall be permitted to supply 120 volts to single-phase, 3-wire, 1201240-volt ser- Exception: A power transformer with a current rating on vice equipment or distribution panels where there are no the side connected toward the photovoltaic power source, 240-volt outlets and where there are no multiwire branch not less than the short-circuit output current rating of the circuits. In all installations, the rating of the overcurrent inverter, shall be permitted without overcurrent protection device connected to the output of the inverter shall be less from that source. than the rating of the neutral bus in the service equipment. This equipment shall be marked with the following words (C) Photovoltaic Source Circuits. Branch-circuit or or equivalent: supplementary-type overcurrent devices shall be permitted to provide overcurrent protection in photovoltaic source cir- WARNING cuits. The overcurrent devices shall be accessible but shall SINGLE 120-VOLT SUPPLY. DO NOT CONNECT not be required to be readily accessible. MULTIWIRE BRANCH CIRCUITS! Standard values of supplementary overcurrent devices allowed by this section shall be in one ampere size incre- (D) Energy Storage or Backup Power System Require- ments, starting at one ampere up to and including 15 am- ments. Energy storage or backup power supplies are not peres. Higher standard values above 15 amperes for supple- required. mentary overcurrent devices shall be based on the standard sizes provided in 240.6(A). III. Disconnecting Means (D) Direct-Current Rating. Overcurrent devices, either 690.13 All Conductors. Means shall be provided to dis- fuses or circuit breakers, used in any do portion of a pho- connect all current-carrying conductors of a photovoltaic tovoltaic power system shall be listed for use in do circuits power source from all other conductors in a building or and shall have the appropriate voltage, current, and inter- other structure. A switch, circuit breaker, or other device, rupt ratings. either ac or dc,shall not be installed in a grounded conduc- tor if operation of that switch, circuit breaker, or other de- (E) Series Overcurrent Protection. In series-connected vice leaves the marked, grounded conductor in an un- strings of two or more modules, a single overcurrent pro- grounded and energized;state. tection device shall be permitted. Exception: A switch or circuit breaker that is part of a 690.10 Stand-Alone Systems. The premises wiring sys- ground fault detection system required by 690.5 shall be tem shall be adequate to meet the requirements of this Code permitted to open the grounded conductor when that switch for a similar installation connected to a service. The wiring or circuit breaker is automatically opened as a normal on the supply side of the building or structure disconnect- function of the device in responding to ground faults. The ing means shall comply with this Code except as modified switch or circuit breaker shall indicate the presence of a by 690.10(A) through (D). ground fault. FPN: The grounded conductor may have a bolted or termi- (A) Inverter Output. The ac output from a stand-alone nal disconnecting means to allow maintenance or trouble- inverter(s) shall be permitted to supply ac power to the shooting by qualified personnel. building or structure disconnecting means at current levels less than the calculated load connected to that disconnect. 690.14 Additional Provisions. Photovoltaic disconnecting The inverter output rating or the rating of an alternate en- means shall comply with 690.14(A) through (D). ergy source shall be equal to or greater than the load posed by the largest Single,utilization equipment Connected to the (A) Disconnecting Means. The disconnecting means shall system. Calculated general lighting loads shall not be con- not be required to be suitable as service equipment and sidered as a single load. shall comply with 690.17. (B) Sizing and Protection. The circuit conductors be- (B) Equipment. Equipment such as photovoltaic source tween the inverter output and the building or structure dis- circuit isolating switches,overcurrent devices,and blocking connecting means shall be sized based on the output rating diodes shall be permitted on the photovoltaic side of the of the inverter. These conductors shall be protected from photovoltaic disconnecting means. 70-580 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE&X)—SOLAR PHOTOVOLTAIC SYSTEMS 69031 (C) Requirements for Disconnecting Means. Means energized from more than one source, the disconnecting shall be provided to disconnect all conductors in a building means shall be grouped and identified. or other structure from the photovoltaic system conductors. A single disconnecting means in accordance with (1) Location. The photovoltaic disconnecting means shall f90.17 shall be permitted for the combined ac output of one be installed at a readily accessible location either on the or more inverters or ac modules in an interactive system. outside of a building or structure or inside nearest the point 690.16 Fuses. Disconnecting means shall be provided to of entrance of the system conductors. disconnect a fuse from all sources of supply if the fuse is energized from both directions and is accessible to other Exception: Installations that comply with 690.31(E} shall than qualified persons. Such a fuse in a photovoltaic source be permitted to have the disconnecting mean.e located re- circuit shall be capable of being disconnected indepen- dently frrNU the point of erltrl of the system Conductors. circuit of fuses in other photovoltaic source circuits. The photovoltaic system disconnecting means shall not 690.17 Switch or Circuit Breaker. The disconnecting be installed in bathrooms. means for ungrounded conductors shall consist of a manu- (2) Marking. Each photovoltaic system disconnecting ally operable switch(es) or circuit breaker(s) complying means shall be permanently marked to identify it as a pho- with all of the following requirements: tovoltaic system disconnect. (1) Located where readily accessible (3) Suitable for Use. Each photovoltaic system discon- (2) Externally operable without exposing the operator to necting means shall be suitable for the prevailing condi- contact with live parts tions. Equipment installed in hazardous (classified) loca- (3) Plainly indicating whether in the open or closed position tions shall comply with the requirements of Articles 500 (4) Having an interrupting rating sufficient for the nominal through 517. circuit voltage and the current that is available at the (4) ]Maximum Number of Disconnects. The photovoltaic line terminals of the equipment system disconnecting means shall consist of not more than Where all terminals of the disconnecting means may be six switches or six circuit breakers mounted in a single energized in the open position, a warning sign shall be enclosure, in a group of separate enclosures, or in or on a mounted on or adjacent to the disconnecting means. The switchboard. sign shall be clearly legible and have the following words or equivalent: (5) Grouping. The photovoltaic system disconnecting means shall be grouped with other disconnecting means for WARNING ELECTRIC SHOCK HAZARD. the system to comply with 690.14(0)(4). A photovoltaic disconnecting means shall not be required at the photovol- DO NOT TOUCH TERMINALS. . TERMINALS ON )30TH THE LINE taic module or array location. AND LOAD SIDES MAY BE ENERGIZED (D) Utility-Interactive Inverters Mounted in Not- IN THE OPEN POSITION, Readily-Accessible Locations. Utility-interactive inverters Exception: A connector shall be permitted to be used as an shall be permitted to be mounted on roofs or other exterior ac or a do disconnecting means, provided that it complies areas that are not readily accessible. These installations with the requirements of 690.33 and is listed and identified shall comply with (1) through (4): fur the use. (1) A direct-current photovoltaic disconnecting means 690.18 Installation and Service of an Array. Open cir- shall be mounted within sight of or in the inverter. cuiting, short circuiting, or opaque covering shall be used (2) An alternating-current disconnecting: means shall be to disable an array or portions of an array for installation mounted within sight of or in the inverter. and service. (3) The alternating-current output conductors from the in- FPN: Photovoltaic modules are energized while exposed to verter and an additional alternating-current disconnect- light. Installation, replacement, or servicing of array com- ing means for the inverter shall comply with ponents while a module(s)is irradiated may expose persons 690.14(C)(1). to electric shock. (4) A plaque shall be installed in accordance with 705.10. 690.15 Disconnection of Photovoltaic Equipment. IV. Wiring Methods Means shall be provided to disconnect equipment, such as 690.31 Methods Permitted. inverters,batteries,charge controllers,and the like, from all (A) Wiring Systems. All raceway and cable wiring meth- ungrounded conductors of all sources. If the equipment is ods included in this Code and other wiring systems and 2008 Edition NATIONAL ELECTRICAL CODE 70-.5$1 690.32 ARTICLE 690-SOLAR PHOTOVOLTAIC SYSTEMS fittings specifically intended and identified for use on pho- (E) Direct-Current Photovoltaic Source and Output tovoltaic arrays shall be permitted. Where wiring devices Circuits Inside a Building.Where direct-current photovol- with integral enclosures are used, sufficient length of cable taic source or output circuits of a utility-interactive inverter shall be provided to facilitate replacement. from a building-integrated or other photovoltaic system are Where photovoltaic Source and output circuits operating run inside a building or structure, they shall be contained in at maximum system voltages greater than 30 volts are in- metal raceways,or metal enclosures, from the point of pen- Stalled in readily accessible locations, circuit conductors etration of the surface of the building or structure to the shall be installed in a raceway. first readily accessible disconnecting means. The discon- FPN: Photovoltaic modules operate at elevated tempera- netting means shall comply with 690.14(A) through (D). tures when exposed to high ambient temperatures and to bright sunlight. These temperatures may routinely exceed (F) Fle7dble, Fine-Stranded Cables. Flexible, fine- 70°C (158°F) in many locations. Module interconnection stranded Cables shall be terminated only With terminals, conductors are available with insulation rated for wet Iota- Iugs,devices,or connectors that are identified and Iisted for tions and a temperature rating of 90°C (194°F) or greater. Such use. (B) Single-Conductor Cable.Single-conductor cable type USE-2, and single-conductor cable listed and labeled as 690.32 Component Interconnections. Fittings and con- photovoltaic (PV) wire shall be permitted is exposed out- nectors that are intended to be concealed at the time of door locations in photovoltaic source circuits for photovol- on-site assembly,where listed for such use, shall be permit- taie module interconnections within the photovoltaic array. ted for on-site interconnection of modules or other array Exception: .Raceways shall be used when required by components. Such fittings and connectors shall be equal to 690.3](A). the wiring method employed in insulation, temperature rise, and fault-current withstand, and shall be capable of resist- (C) Flexible Cords and Cables. Flexible cords and ing the effects of the environment in which they are used. cables, where used to connect the moving parts of tracking PV modules, shall comply with Article 400 and shall be of 690.33 Connectors. The connectors permitted by Article a type identified as a hard service cord or portable power 690 shall comply with 690.33(A) through (E). cable, they shall be suitable for extra-hard usage, listed for outdoor use, water resistant, and sunlight resistant. Allow- (A) Configuration. The connectors shall be polarized and able ampacities shall be in accordance with 400.5. For am- shall have a configuration that is noninterchangeable with bient temperatures exceeding 3WC (86°F), the ampacities receptacles in other electrical systems on the premises. shall be derated by the appropriate factors given in Table 690.31(C). (B) Guarding. The connectors shall be constructed and installed so as to guard against inadvertent contact with live (D) Small-Conductor Cables. Single-conductor cables parts by persons. listed for outdoor use that are sunlight resistant and mois- ture resistant in sizes 16 AWG and 18 AWG shall be per- (C) Type. The connectors shall be of the latching or lock- mitted for module interconnections where such cables meet ing type.Connectors that are readily accessible and that are the ampacity requirements of 690.8. Section 310.15 shall used in circuits operating at over 30 volts, nominal, maxi- be used to determine the cable ampacity and temperature mum system voltage for do circuits, or 30 volts for ac derating factors. circuits, shall require a tool for opening. Table 690.31(C) Correction Factors Ambient Temperature Rating of Conductor Ambient Temperature Temperature CQ 60°C (140°F) 75°C (167°F) 90°C (194°F) 105°C (221°F) (°F) 30 1.00 I.00 1.00 1.00 86 31-35 0.91 0.94 0.96 0.97 87-95 36-40 0.82 0.88 0.91 0.93 96-104 41-45 0.71 0.82 0.87 0.89 105-113 46-50 0.58 0.75 0.82 0.86 114-122 51-55 0.41 0.67 0.76 0.82 123-131 56-60 - 0.58 0.71 0.77 132-140 61-70 - 0.33 0.58 0.68 141-158 71-80 - - 0.41 0.58 159-176 70-582 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 690—SOLAR PHOTOVOLTAIC SYSTEMS 690.43 (D) Grounding Member.The grounding member shall be connect, and device where energised, ungrounded circuits the first to make and the last to break contact with the may be exposed during service: mating connector. WARNING (E) Interruption of Circuit.Connectors shall be either(1) ELECTRIC SHOCK HAZARD. or (2): THE DC CONDUCTORS OF THIS (1) Be rated for interrupting current without hazard to the PHOTOVOLTAIC SYSTEM ARE UNGROUNDED operator. AND MAY BE ENERGIZED. (2) Be a type that requires the use of a tool to open and (G) The inverters or charge controllers used in systems marked "Do Not Disconnect Under Load" or "Not for with ungrounded photovoltaic source and output circuits Current Interrupting." shall be listed for the purpose. 690.34 Access to Boxes. Junction, pull, and outlet boxes located behind modules or panels shall be so installed that V. Grounding the wiring contained in them can be rendered accessible directly or by displacement of a module(s) or panel(s) se- 690.41 System Grounding. For a photovoltaic power cured by removable fasteners and connected by a flexible source, one conductor of a 2-wire system with a photovol- wiring system. taic system voltage over 50 volts and the reference (center tap) conductor of a bipolar system shall be solidly 690.35 Ungrounded Photovoltaic Power Systems. Pho- grounded or shall use other methods that accomplish tovoltaic power systems shall be permitted to operate with equivalent system protection in accordance with 250.4(A) ungrounded photovoltaic source and output circuits where and that utilize equipment listed and identified for the use. the system complies with 690.35(A) through (G). Exception: Systems complying with 690.35, (A) Disconnects. All photovoltaic source and output cir- cuit conductors shall have disconnects complying with 690, 690.42 Point of System Grounding Connection. The do Part III. circuit grounding connection shall be made at any single point on the photovoltaic output circuit, (B) Overcurrent Protection. All photovoltaic source and output circuit conductors shall have overcurrent protection FPN: Locating the grounding connection point close as practicable to the photovoltaic source better protects tects the complying with 690.9. system from voltage surges due to lightning. (C) Ground-Fault Protection. All photovoltaic source and Exception: Systems with a 690.5 ground-fault protection output circuits shall be provided with a ground-fault protection device shall be permitted to have the required grounded device or system that complies with (1) through (3): conductor-to-ground bond made by the ground fault pro- (1) Detects a ground fault. tection device. This bona where internal to the ground- (2) Indicates that a ground fault has occurred fault equipment, shall not be duplicated with an external (3) Automatically disconnects all conductors or causes the connection. inverter or charge controller connected to the faulted circuit to automatically cease supplying power to out- 690.43 Equipment Grounding. Exposed non-current- put circuits. carrying metal parts of module frames, equipment, and con- ductor enclosures shall be grounded in accordance with (D)The photovoltaic source conductors shall consist of the 250.134 or 250.t36(A)regardless of voltage.An equipment following: grounding conductor between a PV array and other equip- (1) Nonmetallic jacketed multiconductor cables ment shall be required in accordance with 250.110. (2) Conductors installed in raceways, or Devices listed and identified for grounding the metallic (3) Conductors listed and identified as Photovoltaic (PV) frames of PV modules shall be permitted to bond the ex- posed metallic frames of PV modules to grounded mount- ing Structures.Devices identified and listed for bonding the (E) The photovoltaic power system direct-current circuits metallic frames of PV modules shall be permitted to bond shall be permitted to be used with ungrounded battery sys- the exposed metallic frames of PV modules to the metallic terns complying with 690.71(G). frames of adjacent PV modules. Equipment grounding conductors for the PV array and (F)The photovoltaic power source shall be labeled with the structure (where installed) shall be contained within the following warning at each junction box, combiner box,dis- same raceway or cable, or otherwise run with the PV array 2008 Edition NATIONAL ELECTRICAL CODE 70-553 690.45 ARTICLE 690--SOLAR PHOTOVOLTAIC SYSTEMS circuit conductors when those circuit conductors leave the current and direct-current grounding requirements shall vicinity of the PV array. comply with items (C)(1) through (C)(8): (1) Where photovoltaic power systems have both 690.45 Size of Equipment Grounding Conductors. alternating-current (ac) and direct-current (dc) ground- Equipment grounding conductors for photovoltaic source ing requirements, the do grounding system shall. be and photovoltaic output circuits shall be sized in accor- bonded to the ac grounding system. dance with 690.45(A) or (8). (2) A bonding conductor between these systems shall be sized as the larger of the do requirement in accordance (A) General. Equipment grounding conductors in photo- with 690.45, the ac requirements based on the inverter voltaic source and photovoltaic output circuits shall be sized in accordance with Table 250.122.Where no overcur- alternating current overcurrent device rating and rent protective device is used in the circuit, an assumed 250.122, and the System bonding requirements of overcurrent device rated at the photovoltaic rated short- circuit current shall be used in Table 250.122. Increases in (3) A conductor that serves as both an equipment ground- equipment grounding conductor size to address voltage ing conductor and as part of the bond between ac and drop considerations shall not be required. The equipment do systems for an inverter incorporating do ground- grounding conductors shall be no smaller than 14 AWG. fault protection shall meet the requirements for equip- ment bonding jumpers in accordance with 250.102 but (B) Ground-Fault Protection Not Provided. For other shall not be subject to the requirements for bonding than dwelling units where ground-fault protection is not jumpers in accordance with 250.28.A single conductor provided in accordance with 690.5(A) through (C), each shall be permitted to be used to perform the multiple equipment grounding conductor shall have an ampacity of functions of do grounding, ac grounding, and bonding at least two (2) times the temperature and conduit 1114 cor- between ac and do systems. rected circuit conductor ampacity. (4) A bonding conductor or equipment grounding conduc- tor that serves multiple inverters shall be sized based FPN: The short-circuit current of photovoltaic modules on the sum of applicable maximum currents used in and photovoltaic sources i5 just slightly above the full-load normal output rating. In ground-fault conditions, these item(2). sources are not able to supply the high levels of short- (5) A common ground bus shall be permitted to be used for circuit or ground-fault currents necessary to quickly acti- both systems. vate overcurrent devices as in typical ac systems. Protec- tion for equipment grounding conductors in photovoltaic (6) A common grounding electrode Shall be permitted to be systems that are not provided with ground-fault protection used for both systems, in which case the grounding is related to size and withstand capability of the equipment electrode conductor shall be connected to the ac ground grounding conductor, rather than overcurrent device system bonding point. operation. (7) Grounding electrode conductor(s) shall be sued to 690.46 Array Equipment Grounding Conductors. meet the requirements of both 250.66 (ac system) and Equipment grounding conductors for photovoltaic modules 250.166 (dc System). smaller than 6 AWG Shall comply with 250.120(C). (8) For systems with utility interactive inverters, the pre- mises grounding system serves as the ac grounding 690.47 Grounding Electrode System. system. (A) Alternating-Current Systems. If installing an ac sys- (D) Additional Electrodes for Array Grounding. tem, a grounding electrode system shall be provided in Grounding electrodes shall be installed in accordance with accordance with 250.50 through 250.60. The grounding 250.52 at the location of all ground- and pole-mounted electrode conductor shall be installed in accordance with photovoltaic arrays and as close as,practicable to the loea- 250.64, tion of roof-mounted photovoltaic arrays. The electrodes shall be connected directly to the array frame(s) or struc- (B) Direct-Current Systems. If installing a do system, a Lure. The do grounding electrode conductor shall be sized grounding electrode system shall be provided in accordance according to 250.166.Additional electrodes are not permit- with 250.166 for grounded systems or 250.169 for un- ted to be used as a Substitute for equipment bonding or grounded systems.The grounding electrode conductor shall equipment grounding conductor requirements. be installed in accordance with 250.64. The structure of a ground- or pole-mounted photovol- taic array shall be per to be considered a grounding (C) Systems with Alternating-Current and Direct-Cur- electrode if it meets the requirements of 250.52. Roof- rent Grounding Requirements. Systems with alternating- mounted photovoltaic arrays shall be permitted to use the 70-584 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 690—SOLAR PHOTOVOLTAIC SYSTEMS 690,57 metal frame of a building or structure if the requirements of 690.53 Direct-Current Photovoltaic Power Source. A 250.52(A)(2) are met, permanent label for the direct-current photovoltaic power source indicating items (I) through (5) shall be provided by Exception No. 1: Array grounding electrode(s)shall not be the installer at the photovoltaic disconnecting means: required where the load served by the array is integral with the array. (1) Rated maximum power-point current (2) Rated maximum power-point voltage Exception Nn. 2: Additions[ array grounding elecirode(s) (3} Maximum system voltage shall not be required if located within 6 ft of the premises wiring electrode. FPN to (3): See 690.7(A) for maximum photovoltaic system voltage. 690.45 Continuity of Equipment Grounding Systems. (4) Short-circuit current Where the removal of equipment disconnects the bonding FPN to (4): See 690.8(A) for calculation of maximum circuit connection between the grounding electrode conductor and Current. exposed conducting surfaces in the photovoltaic source or (5) Maximum rated output current of the charge controller output circuit equipment, a bonding jumper shall be in- (if installed) stalled while the equipment is removed. FPN: Reflecting systems used for irradiance enhancement 690.49 Continuity of Photovoltaic Source and Output may result in increased levels of output current and power. Circuit Grounded Conductors. Where the removal of the utility-interactive inverter or other equipment disconnects 690.54 Interactive System Point of Interconnection. All the bonding connection between the grounding electrode interactive system(s) points of interconnection with other conductor and the photovoltaic source and/or photovoltaic sources shall be marked at an accessible location at the output circuit grounded conductor, a bonding jumper shall disconnecting means as a power source and with the rated be installed to maintain the system grounding while the ac output current and the nominal operating ac voltage. inverter or other equipment is removed. 690.55 Photovoltaic Power Systems Employing Energy 690.50 Equipment Bonding Jumpers. Equipment bond- Storage. Photovoltaic power systems employing energy storage shall also be marked with the maximum operating ing jumpers, if used,shall comply with 250.I20(C}. voltage, including any equalization voltage and the polarity of the grounded circuit conductor. VI. Marking 690.56 Identification of Power Sources. 690.51 Modules.Modules shall be marked with identifica- tion of terminals or leads as to polarity, maximum overcur- (A) Facilities with Stand-Alone Systems. Any structure rent device rating for module protection, and with the fol- or building with a photovoltaic power system that is not lowing ratings: connected to a utility service source and is a stand-alone (1) Open-circuit voltage system shall have a permanent plaque or directory installed (2) Operating voltage on the exterior of the building or structure at a readily (3) Maximum permissible system voltage visible location acceptable to the authority having jurisdic- tion. The plaque or directory shall indicate the location of (4) Operating current system disconnecting means and that the structure contains (5) Short-circuit current a stand-alone electrical power system. (6) Maximum power (B) Facilities with Utility Services and PV Systems, 690.52 Alternating-Current Photovoltaic Modules. Buildings or structures with both utility service and a pho- Alternating-current modules shall be marked with identifi- tovoltaic system shall have a permanent plaque or directory cation of terminals or leads and with identification of the providing the location of the service disconnecting means following ratings: and the photovoltaic system disconnecting means if not (1) Nominal operating ac voltage located at the same location. (2) Nominal operating ac frequency (3) Maximum ac power VII. Connection to Other Sources (4) Maximum ac current 690.57 Load Disconnect. A load disconnect that has mul- (5) Maximum overcurrent device rating for ac module tiple sources of power shall disconnect all sources when in protection the off position. 2008 Edition NATIONAL ELECTRICAL CODE 70-585 690.60 ARTICLE 690—SOLAR PHOTOVOLTAIC SYSTEMS 690.60 Identified Interactive Equipment. Only inverters service disconnecting means of the other source(s) at any and ac modules listed and identified as interactive shall be distribution equipment on the premises. Where distribution permitted in interactive systems. equipment, including switchboards and panelboards, is fed simultaneously by a ,primary source(s) of electricity and 690.61 Loss of Interactive System Power. An inverter or one or more utility-interactive inverters,and where this dis- an ac module in an interactive solar photovoltaic system tribution equipment is capable of supplying multiple branch shall automatically de-energize its output to the connected circuits or feeders, or both, the interconnecting provisions electrical production and distribution network upon loss of for the utility-interactive inverter(s) shall Comply with voltage in that system and shall remain in that state until (13)(1)through(13)(7). the electrical production and distribution network voltage has been restored. (1) Dedicated Qvercurrent and Disconnect. Each source A normally interactive solar photovoltaic system shall interconnection shall be made at a dedicated circuit breaker be permitted to operate as a stand-alone system to supply or fusible disconnecting means. loads that have been disconnected from electrical produc- (2) Bus or Conductor Rating. The sum of the ampere tion and distribution network sources. ratings of overcurrent devices in circuits supplying power to a busbar or conductor shall not exceed 120 percent of the 690.62 Ampacity of Neutral Conductor. If a single- rating of the bulbar or conductor. In systems with panel- phase, 2-wire inverter output is connected to the neutral boards connected in series, the rating of the first overcur- conduetor and one ungrounded conductor(only)of a 3-wire rent device directly connected to the output of a utility- system or of a 3-phase, 4-wire, wye-connected system, the interactive inverter(s) shall be used in the calculations for maximum load connected between the neutral conductor and all busbars and conductors. any one ungrounded conductor plus the inverter output rating shall not exceed the ampacity of the neutral conductor. (3) Ground-Fault Protection. The interconnection point A conductor used solely for instrumentation, voltage Shall be on the line Side of all ground-fault protection detection, or phase detection, and connected to a single- equipment. phase or 3-phase utility-interactive inverter, shall be per- Exception: Connection shall be permitted to be made to mitted to be sized at less than the ampacity of the other the load side of, round fault protection,provided that there current-carrying conductors and shall be sized equal to or is ground fault protection for equipment from all ground- fault than the equipment grounding conductor. fault current sources. Ground-fault protection devices used 690.63 Unbalanced Interconnections. with supplies connected to the loan!-side terminals shall be identified and listed as suitable for backfeeding. (A) Single Phase. Single-phase inverters for photovoltaic systems and ac modules in interactive solar photovoltaic (4) Marlting.Equipment containing overcurrent devices in circuits supplying power to a busbar or conductor supplied systems shall not be connected to 3-phase power systems from multiple sources shall be marked to indicate the pres- unless the interconnected system is designed so that signifi- ence of all sources. cant unbalanced voltages cannot result. (5) Suitable for Bacltfeed. Circuit breakers, if backfed, (B) Three Phase. Three-phase inverters and 3-phase ac shall be suitable for such operation. modules in interactive systems shall have all phases auto- matically de-energized upon loss of,or unbalanced, voltage FPN: Circuit breakers that are marked"Line"and"Load" in one or more phases unless the interconnected system is have been evaluated only in the direction marked. Circuit breakers without"Line"and"Load"have been evaluated in designed so that significant unbalanced voltages will not both directions. result. (6) Fastening.Listed plug-in-type circuit breakers backfed 690.64 Point of Connection. The output of a utility- from utilxty-interactive inverters complying with 690.60 interactive inverter shall be connected as specified in shall be permitted to omit the additional fastener normally 690.64(A) or (B). required by 408.36(D) for such applications. (A) Supply Side. The output of a utility-interactive in- (7) Inverter Output Connection. Unless the panelboard verter shall be permitted to be connected to the supply side is rated not less than the sum of the ampere ratings of all of the service disconnecting means as permitted in overcurrent devices supplying it, a connection in a panel- 230.82(6). board shall be positioned at the opposite (load) end from the input feeder location or main circuit location.The bus (B) Load Side. The output of a utility-interactive inverter or conductor rating shall be sized for the loads connected in shall be permitted to be connected to the load side of the accordance with Article 220. A permanent warning label 70-586 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 640—SOLAR PHOTOVOLTAIC SYSTEMS 690,72 shall be applied to the distribution equipment with the fol- (E) Disconnection of Series Battery Circuits.Battery cir- lowing or equivalent marking: cuits subject to field servicing, where more than twenty- four 2-volt cells are connected in series (48 volts,nominal), WARNING RE CONNECTION shall have provisions to disconnect the series-connected INVERTER Q[JT strings into segments of 24 cells or less for maintenance by DO NOT RELOCATE THIS OVERCURRENT DEVICE qualified persons.Non-load-break bolted or plug-in discon- nects shall be permitted, VIII. Storage Batteries (F) Battery Maintenance Disconnecting Means. Battery installations, where there are more than twenty-four 2-volt 690.71 Installation. cells connected in series (48 volts, nominal), shall have a disconnecting means, accessible only to qualified persons, (A) General. Storage batteries in a solar photovoltaic sys- that disconnects the grounded circuit conductor(s) in the tem shall be installed in accordance with the provisions of battery electrical system for maintenance. This disconnect- Article 480. The interconnected battery cells shall be con- ing means shall not disconnect the grounded circuit con- sidered grounded where the photovoltaic power source is ductor(s) for the remainder of the photovoltaic electrical installed in accordance with 690.41. system. A non-load-break-rated switch shall be permitted (B) Dwellings. to be used as the disconnecting means. (1) Operating Voltage. Storage batteries for dwellings (G) Battery Systems of More Than 48 Volts. On photo- shall have the cells connected so as to operate at less than voltaic systems where the battery system consists of more 50 volts nominal. Lead-acid storage batteries for dwellings than twenty-four 2-volt cells connected in series(more than shall have no more than twenty-four 2-volt cells connected 48 volts, nominal), the battery system shall be permitted to in series (48-volts nominal). operate with ungrounded conductors, provided the follow- Exception: Where live parts are not accessible during rou ing conditions are met: tine hatter), maintenance, a batten' system voltage in ac- (1) The photovoltaic array source and output circuits shall cordance with 690.7 shall be permitted. comply with 690.41. (2) The do and ac load circuits shall be solidly grounded. (2) Guarding of Live Parts. Live parts of battery systems (3) All main ungrounded battery input/output circuit con- for dwellings shall be guarded to prevent accidental contact ductors shall be provided with switched disconnects by persons or objects, regardless of voltage or battery type. and overcurrent protection. FPN: Batteries in solar photovoltaic systems are subject to (4) A ground-fault detector and indicator shall be installed extensive charge-discharge cycles and typically require fre- to monitor for ground faults in the battery bank. quent maintenance, such as checking electrolyte and clean- ing connections. 690.72 Charge Control. (C) Current Limiting. A listed, current-limiting, overcur- (A) General. Equipment shall be provided to control the rent device shall be installed in each circuit adjacent to the charging process of the battery. Charge control shall not be batteries where the available short-circuit current from a required where the design of the photovoltaic source circuit battery or battery bank exceeds the interrupting or with- is matched to the voltage rating and charge current require- stand ratings of other equipment in that circuit. The instal- ments of the interconnected battery cells and the maximum lation of current-limiting fuses shall comply with 690,16, charging current multiplied by 1 hour is less than 3 percent of the rated battery capacity expressed in ampere-hours or (D) Battery Nonconductive Cases and Conductive as recommended by the battery manufacturer. Racks. Flooded, vented, lead-acrid batteries with more than All adjusting means for control of the charging process twenty-four 2-volt cells connected in series (48 volts, nomi- shall be accessible only to qualified persons. nal) shall not use conductive cases or shall not be installed in conductive cases, Conductive racks used to support the FPN: Certain battery types such as valve-regulated lead nonconductive cases shall be permitted where no rack ma- acid or nickel cadmium can experience thermal failure terial is located within 150 mm (6 in.) of the tops of the when overcharged. nonconductive cases. (B) Diversion Charge Controller. This requirement shall not apply to any type of valve-regulated lead-acid (VRLA) battery or any other (1) Sole Means of Regulating Charging. A photovoltaic types of sealed batteries that may require steel cases for power system employing a diversion charge controller as proper operation. the sole means of regulating the charging of a battery shall 2008 Edition NATIONAL ELECTRICAL.CODE 70_587 690.74 ARTICLE 692—FUEL CELL SYSTEMS be equipped with a second independent means to prevent Photovoltaic Circuits. In do photovoltaic source circuits and overcharging of the battery. photovoltaic output circuits, the maximum system voltage. (2) Circuits with Direct-Current Diversion Charge Controller and Diversion Load. Circuits containing a do diversion charge controller and a do diversion load shall comply with the following: ARTICLE 692 (1) The current rating of the diversion load shall be less Fuel Cell Systems than or equal to the current rating of the diversion load charge controller.The voltage rating of the diversion load shall be greater than the maximum battery voltage. The 1. General power rating of the diversion load shall be at least 692.1 Scope. This article identifies the requirements for 150 percent of the power rating of the photovoltaic array, the installation of fuel cell power systems, which may be (2) The conductor ampacity and the rating of the overcur- stand-alone or interactive with other electric power produc- rent device for this circuit shall be at least 150 percent tion sources and may be with or without electric energy of the maximum current rating of the diversion charge storage such as batteries.These systems may have ac or do controller. output for utilization. (3) PV Systems Using Utility-Interactive Inverters.Pho- tovoltaic power systems using utility-interactive inverters 692.2 Definitions. to control battery state-of-charge by diverting excess power Fuel Cell.An electrochemical system that consumes fuel to into the utility system shall comply with (1) and (2): produce an electric current. The main chemical reaction (1) These systems shall not be required to comply with used in a fuel cell for producing electric power is not com- 690.72(B)(2). The charge regulation circuits used shall bustion, However, there may be sources of combustion comply with the requirements of 690.8. used within the overall fuel cell system such as (2) These systems shall have a second, independent means reformers/fuel processors. of controlling the battery charging process for use when the utility is not present or when the primary Fuel Cell System. The complete aggregate of equipment charge controller fails or is disabled. used to convert chemical fuel into usable electricity.A fuel cell system typically consists of a reformer, stack, power 690.74 Battery Interconnections. Flexible cables, as inverter, and auxiliary equipment. identified in Article 400, in sizes 2/0 AWG and larger shall Interactive System. A fuel cell system that operates in be permitted within the battery enclosure from battery ter- parallel with and may deliver power to an electrical produc- minals to a nearby junction box where they shall be con- tion and distribution network. For the purpose of this defi- nected to an approved wiring method. Flexible battery nition, an energy storage subsystem of a fuel cell system, cables shall also be permitted between batteries and cells such as a battery, is not another electrical production within the battery enclosure. Such cables shall be listed for source. hard-service use and identified as moisture resistant. Flexible, fuse-stranded cables Shali only be used with Maximum System Voltage. The highest fuel cell inverter terminals, lugs, devices, and connectors that are Iisted and output voltage between any ungrounded conductors present marked for such use. at accessible output terminals. Output Circuit. The conductors used to connect the fuel IX. Systems over 600 Volts cell system to its electrical point of delivery. In the case of sites that have series- or parallel-connected multiple units, 690.80 General. Solar photovoltaic systems with a maxi- the term output circuit also refers to the conductors used to mum system voltage over 600 volts do shall comply with electrically interconnect the fuel cell system(s). Article 490 and other requirements applicable to installa- tions rated over 600 volts. Point of Common Coupling.The point at which the power production and distribution network and the customer inter- 690.85 Definitions. For the purposes of Part IX of this face occurs in an interactive system. Typically, this is the article, the voltages used to determine cable and equipment load side of the power network meter. ratings are as follows. Stand-Alone System. A fuel cell system that supplies Battery Circuits. In battery circuits, the highest voltage power independently of an electrical production and distri- experienced under charging or equalizing conditions. bution network. 70-588 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 692—FUEL CELL SYSTEMS 692.17 692.3 Other Articles. Wherever the requirements of other 692.10 Stand-Alone Systems. The premises wiring sys- articles of this Cade and Article 692 differ,the requirements tem shall meet the requirements of this Code except as of Article 692 shall apply, and, if the system is operated in modified by 692.10(A), (B), and (C). parallel with a primary source(s) of electricity, the require- ments in 705.14, 705.16, 705.32, and 705.143 shall apply. (A) Fuel Cell System Output. The fuel cell system out- put from a stand-alone system shall be permitted to sup- 692.4 Installation. ply ac power to the building or structure disconnecting means at current levels below the rating of that discon- (A) Fuel Cell System. A fuel cell system shall be permit- necting means. ted to supply a building or other structure in addition to any service(s) of another electricity supply system(s). (B) Sizing and Protection. The circuit conductors be- tween the fuel cell system(s) output and the building or (B) Identifiication. A permanent plaque or directory, de- structure disconnecting means shall be sized based on the noting all electric power sources on or in the premises, output rating of the fuel cell system(s). These conductors shall be installed at each service equipment location. shall be protected from overcurrents in accordance with 240.4. The overcurrent protection shall be located at the 692.6 Listing Requirement. The fuel cell system shall be output of the fuel cell system(s). evaluated and listed for its intended application prior to installation. (C) Single 120-Volt Nominal Supply. The inverter output of a stand-alone fuel cell system shall be permitted to sup- ply 120 volts, nominal, to single-phase, 3-wire 120/240- II. Circuit Requirements volt service equipment or distribution panels where there are no 240-volt loads and where there are no multiwire 692.8 Circuit Sizing and Current. branch circuits. In all installations, the rating of the over- (A) Nameplate Rated Circuit Current.The nameplate(s) current device connected to the output of the fuel cell sys- rated circuit current shall be the rated current indicated on tem(s) shall be less than the rating of the service equip- the fuel cell nameplate(s). ment. This equipment shall be marked as follows: (B) Conductor Ampacity and Overcurrent Device Rat- WARNING SINGLE 120-VOLT SUPPLY. ings. The ampacity of the feeder circuit conductors from DO NOT CONNECT MULTIWIRE the fuel cell system(s) to the premises wiring system shall BRANCH CIRCUITS! not be less than the greater of(1) nameplate(s) rated circuit current or (2) the rating of the fuel cell system(s) overcur- rent protective device(s). III. Disconnecting Means (C) Ampacity of Grounded or Neutral Conductor. If an 692.13 All Conductors. Means shall be provided to dis- interactive single-phase, 2-wire fuel cell output(s) is con- connect all current-carrying conductors of a fuel cell sys- nected to the grounded or neutral conductor and a single tem power source from all other conductors in a building or ungrounded conductor of a 3-wire system or of a 3-phase, other structure. 4-wire, wye-connected system, the maximum unbalanced neutral load current plus the fuel cell system(s) output rat- 692.14 Provisions. The provisions of 225.31 and 225.33 ing shall not exceed the ampacity of the grounded or neu- tral through 225.40 shall apply to the fuel cell source discon- tral conductor. necting means. The disconnecting means shall not be re- quired to be suitable as service equipment and shall be 692.9 Overcurrent Protection. rated in accordance with 692.17. (A) Circuits and Equipment. If the fuel cell system is 692.17 Switch or Circuit Breaker. The disconnecting provided with overcurrent protection sufficient to protect means for ungrounded conductors shall consist of readily the circuit conductors that supply the load, additional cir- accessible, manually operable switch(es) or circuit cuit overcurrent devices shall not be required. Equipment breaker(s). and conductors connected to more than one electrical Where all terminals of the disconnecting means may be source shall be protected. energized in the open position, a warning sign shall be mounted on or adjacent to the disconnecting means. The (B) Accessibility. Overcurrent devices shall be readily sign shall be clearly legible and shall have the following accessible. words or equivalent: 2008 Edition NATIONAL ELECTRICAL CODE 70-589 692.31 ARTICLE 692—FUEL CELL SYSTEMS DANGER 692.54 Fuel Shut-Off. The location of the manual fuel ELECTRIC SHOCK HAZARD, shut-off valve shall be marked at the location of the primary DO NOT TOUCH TERMINALS. disconnecting means of the building or circuits supplied. TERMINALS ON BOTH THE LINE AND LOAD SIDES MAY BE ENERGIZED 692.56 Stored Energy. A fuel cell system that stores elec- IN THE OPEN POSITION. tric energy shall require the following warning sign, or equivalent, at the location of the service disconnecting 1V. Wiring Methods means of the premises: 692.31 Wiring Systems. All raceway and cable wiring WARNING methods included in Chapter 3 of this Code and other wir- FUEL CELL POWER SYSTEM CONTAINS ing systems and fittings specifically intended and identified ELECTRICAL ENERGY STORAGE DEVICES. for use with fuel cell systems shall be permitted. Where wiring devices with integral enclosures are used, sufficient VII. Connection to Other Circuits length of cable shall be provided to facilitate replacement. 692.59 Transfer Switch. A transfer switch shall be re- V. Grounding quired in non--grid-interactive systems that use utility grid backup. The transfer switch shall maintain isolation be- 692.41 System Grounding. tween the electrical production and distribution network (A) AC Systems.Grounding of ac systems shall be in actor and the fuel cell system. The transfer switch shall be per- dance with 25020,and with 250.30 for Stand-alone Systems, mitted to be located externally or internally to the fuel cell system unit. When the utility service conductors of the (B) DC Systems. Grounding of de Systems shall be in ac- structure are connected to the transfer switch, the switch cordance with 350.160. shall comply with Article 230, Part V. (C) Systems with Alternating-Current and Direct- 692.60 Identified Interactive Equipment. Only fuel cell Current Grounding Requirements.When fuel cell power systems have both alternating-current (ac) and direct- systems listed and identified as interactive shall be permit- current(dc)"grounding requirements,the de grounding Sys- ted in interactive systems. tem shall be bonded to the ac grounding system.The bond- ing Conductor shall be sized according to 692.45.A Single 692.61 Output Characteristics. The output of a fuel cell common grounding electrode and grounding bar may be system operating in parallel with an electric supply system used for both systems, in which case the common ground- shall be compatible with the voltage, wave shape, and fre- ing electrode conductor shall be sized to meet the require- quency of the system to which it is connected. ments of both 250.66 (ac) and 250.166 (dc). FPN: The term compatible does not necessarily mean 692.44 Equipment Grounding Conductor. A separate matching the primary source wave shape. equipment grounding conductor shall be installed. 692.62 Loss of Interactive System Power. The fuel cell 692.45 Size of Equipment Grounding Conductor. The system shall be provided with a means of detecting when equipment grounding conductor shall be sized in actor- the electrical production and distribution network has be- dance with 250.122. come de-energized and shall not feed the electrical produc- tion and distribution network side of the point of common 692.47 Grounding Electrode System. Any auxiliary coupling during this condition. The fuel cell system shall grounding electrode(s) required by the manufacturer shall remain in that state until the electrical production and dis- be connected to the equipment grounding conductor speci- tribution network voltage has been restored, fied in 250.118. A normally interactive fuel cell system shall be permit- ted to operate as a stand-alone system to supply loads that VI. Marking have been disconnected from electrical production and dis- tribution network sources. 692.53 Fuel Cell Power Sources. A marking specifying the fuel cell system, output voltage, output power rating, 692.64 Unbalanced Interconnections. and continuous output current rating shall be provided at the disconnecting means for the fuel cell power source at an (A) Single Phase, Single-phase interactive fuel cell sys- accessible location on the site. tems shall not be connected to a 3-phase power system 70-590 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 695—FIRE PUMPS 695.1 unless the interactive system is so designed that significant FPN: Circuit breakers that are marked"Line"and"Load" unbalanced voltages cannot result. have been evaluated only in the direction marked. Circuit breakers without"Line"and"Load"have been evaluated in (B) Three Phase.Three-phase interactive fuel cell systems both directions. shall have all phases automatically de-energized upon loss of voltage, or upon unbalance of voltage in one or more (6) Fastening.Listed plug-in-type circuit breakers backfed from utility-interactive inverters complying with 692.150 phases, unless the interactive system is designed so that shall be permitted to omit the additional fastener normally significant unbalanced voltages will not result. required by 408.36(D) for such applications. 692.65 Utility-Interactive Point of Connection. The out- (7) Inverter Output Connection. lWess the panelboard put of a utility-interactive inverter shall be connected as is rated not less than the sum of the ampere ratings of all specified in 692.65(A) or (B). overcurrent devices supplying it, a connection in a panel- (A) Supply Side. The output of a utility-interactive in- board shall be positioned at the opposite (load) end from verter shall be permitted to be,connected to the supply side the input feeder location or main circuit location. The bus of the service disconnecting means as permitted in or conductor rating shall be sized for the loads connected in 230.82(6). accordance with Article 220. A permanent warning label shall be applied to the distribution equipment with the fol- (B) Load Side. The output of a utility-interactive inverter lowing or equivalent wording: shall be permitted to be connected to the load side of the WARNING service disconnecting means of the other source(s) at any INVERTER OUTPUT CONNECTION distribution equipment on the premises. Where distribution DO NOT RELOCATE THIS OVERCURRENT equipment, including switchboards and panelboards, is fed DEVICE simultaneously by a primary source(s) of electricity and one or more urility-interactive inverters, and where this dis- tribution equipment is capable of supplying multiple branch VIII. Outputs Over 600 Volts circuits or feeders, or both, the interconnecting provisions for the utility-interactive inverter(s) shall comply with 692.80 General Fuel cell systems with a maximum output voltage over 600 volts ac shall comply with the require- (B)(1) through (13)(7). ments of other articles applicable to such installations. (I.) Dedicated Overcurrent and Disconnect. Each source interconnection shall be made at a dedicated circuit breaker or fusible disconnecting means. (2) Bus or Conductor Rating. The sum of the ampere ARTICLE 695 ratings of overcurrent devices in circuits supplying power Fire Pumps to a busbar or conductor shall not exceed 120 percent of the rating of the busbar or conductor. 695.1 Scope. (3) Ground-Fault Protection. The interconnection point shall be on the line side of all ground-fault protection cone Rules that are followed by a reference in brackets contain text that has been extracted From NFPA 20-2007, equipment. Standard for the Installation of Stationary Pumps for Fire Exception: Connection shall be permitted to be made to Protection. Only editorial changes were made to the ex- the load side of ground fault protection,provided that there traded text to make it consistent with this Code. is ground fault protection for equipment from all ground- (A) Covered. This article covers the installation of the fault current sources. Ground-fault protection devices used following: with supplies connected to the load-side terminals shall be (1) Electric power sources and interconnecting circuits identified and listed as suitable for backfeeding. (2) Switching and control equipment dedicated to fire (4) Marking.Equipment containing overcurrent devices in pump drivers circuits supplying power to a busbar or conductor supplied (B) Not Covered.This article does not cover the following: from multiple sources shall be marked to indicate the pres- enee of all sources. (I) The performance, maintenance, and acceptance testing of the fire pump system, and the internal wiring of the (5) Suitable for Backfeed. Circuit breakers, if backfed, components of the system shall be suitable for such operation. (2) Pressure maintenance (jockey or makeup) pumps 2008 Edition NATIONAL ELECrRICAL CODE 70-591 695.2 ARTICLE 695—FIRE PUMPS FPN: See NFPA 20-2007, Standard for the Installation more of such power sources in combination with an on-site of Stationary Pumps for Fire Protection, for further standby generator complying with 695.3(B)(1) and (13)(3). information. (1) Generator Capacity. An on-site generator(s) used to 695.2 Definitions. comply with this section shall be of sufficient. capacity to Fault-Tolerant External Control Circuits. Those control allow normal starting and running of the motor(s) driving the fire pumps) while supplying all other simultaneously circuits either entering or leaving the fire pump controller operated load.Automatic shedding of one or more optional enclosure, which if broken, disconnected, or shorted will standby loads in order to comply with this capacity require- not prevent the controller from starting the fire pump from ment shall be permitted. A tap ahead of the on-site genera- all other internal or external means and may cause the con- for disconnecting means shall not be required. The require- ments of 430.113 shall not apply. [20.9,6.1] On-Site Power Production Facility.The normal supply of electric power for the site that is expected to be constantly (2) Feeder Sources. This section applies to multibuilding campus-style complexes with fire pumps at one or more producing power. buildings. Where sources in 695.3(A) are not practicable, On-Site Standby Generator. A facility producing electric and with the approval of the authority having jurisdiction, power on site as the alternate supply of electric power. It two or more feeder sources shall be permitted as one power differs from an on-site power production facility,in that it is source or as more than one power source where such feed- not constantly producing power. ers are connected to or derived from separate utility ser- vices. The connection(s), overcurrent protective device(s), 695.3 Power Source(s) for Electric Motor-Driven Fire and disconnecting means for such feeders shall meet the Pumps. Electric motor-driven fire pumps shall have a reli- requirements of 695.4(B). [20:9.2.2(4)] able source of power. (3) Arrangement.The power sources shall be arranged so (A) Individual Sources. Where reliable, and where ca- that a fire at one source will not cause an interruption at the pable of carrying indefinitely the sum of the locked-rotor other source. current of the Fire pump motor(s) and the pressure mainte- nance pump motor(s) and the full-load current of the asso- 695.4 Continuity of Power. Circuits that supply electric ciated fire pump accessory equipment when connected to motor-driven fire pumps shall be supervised from inadvert- this power supply, the power source for an electric motor ent disconnection as covered in 695.4(A) or (B). driven fire pump shall be one or more of the following. (A) Direct Connection. The supply conductors shall di- (1) Electric Utility Service Connection.A fire pump shall rectly connect the power source to either a listed fire pump be permitted to be supplied by a separate service, or from a controller or listed combination fire pump controller and connection located ahead of and not within the same cabi- power transfer switch. net,enclosure,or vertical switchboard section as the service Where the power Source is supplied by on-site genera- disconnecting means. The connection shall be located and tor(s), the supply conductors Shall connect to a generator arranged so as to minimize the possibility of damage by fire disconnecting means dedicated for the purposes of serving from within the premises and from exposing hazards.A tap the fire.pump.The disconnecting means shall be located in ahead of the service disconnecting means shall comply with a Separate enclosure from the other generator disconnecting 230.$2(5). The service equipment shall comply with the means. labeling requirements in 230.2 and the location require- ments in 230.72(B). [20:9.2.2] {B} Supervised Connection. A single disconnecting means and associated overcurrent protective device(s) shall (2) On-Site Power Production Facility.A fire pump shall be permitted to be installed between a remote power source be permitted to be supplied by an on-site power production and one of the following: facility.The source facility shall be located and protected to (1) A listed fire pump controller minimize the possibility of damage by fire. [20:9.2.3] (2) A listed fire pump power transfer switch (B) Multiple Sources.Where reliable power cannot be ob- (3) A listed combination fire pump controller and power tained from a source described in 695.3(A), power shall be transfer switch supplied from an approved combination of two or more of For systems installed under the provisions of either of such sources, or from an approved combination of 695.3(B)(2) only, such additional disconnecting means and feeders constituting two or more power sources as covered associated overcurrent protective device(s) shall be permit- in 695.3(B)(2), or from an approved combination of one or ted as required to comply with other provisions of this 70-592 NATIONAL.ELECTRICAL CODE 2008 Edition ARTICLE 695—FIRE PUMPS 695.6 Cade. Overcurrent protective devices between an on-site and overcurrent protective devices shall be permitted to be standby generator and a fire pump controller shall be se- installed between the system supply and the fire pump con- lected and sized according to 430.62 to provide short- troller in accordance with 695.5(A) and (B), or with (C). circuit protection only. All disconnecting devices and over- Only transformers covered in 695.5(C) shall be permitted current protective devices that are unique to the fire pump to supply loads not directly associated with the fire pump loads shall comply with 695.4(B)(1) through (B)(5). system. (1) Overcurrent Device Selection. The overcurrent pro- (A) Size. Where a transformer supplies an electric motor tective device(s)shall be selected or set to carry indefinitely driven fire pump, it shall be rated at a minimum of 125 per- the sum of the locked-rotor current of the fire pump mo- cent of the sum of the fire pump motor(s) and pressure tor(s) and the pressure maintenance pump motor(s) and the maintenance um (s) motor loads, and 100 full-load current of the associated fire pump accessory p p percent of the equipment when connected to this power supply. The next associated fire pump accessory equipment supplied by the standard overcurrent device shall be used in accordance transformer. with 240.6.The requirement to carry the locked-rotor currents (B) Overcurrent Protection. The primary overcurrent indefinitely shall not apply to conductors or devices other than protective device(s) shall be selected or set to carry indefi- overcurrent devices in the fire pump motor circuit(s). nitely the sum of the locked-rotor current of the fire pump (2) Disconnecting Means. The disconnecting means shall motor(s) and the pressure maintenance pump motor(s) and comply with all of the following: the full-load current of the associated fire pump accessory (1) Be identified as suitable for use as service equipment equipment when connected to this power supply. Secondary (2) Be lockable in the closed position overcurrent protection shall not be permitted. The require- (3) Not be located within equipment that feeds loads other ment to carry the locked-rotor currents indefinitely shall not than the fire pump apply to conductors or devices other than overcurrent de- (4) Be located sufficiently remote from other building or vices in the fire pump motor circuit(s), other fire pump source disconnecting means such that (C) Feeder Source. Where a feeder source is provided in inadvertent operation at the same time would be accordance with 695.3(B)(2), transformers supplying the unlikely fire pump system skxill be permitted to .9upply other loads. (3) Disconnect Marking. The disconnecting means shall All other loads shall be calculated in accordance with Ar- be marked "Fire Pump Disconnecting Means." The letters ticle 220, including demand factors as applicable. shall be at least 25 mm (1 in.) in height, and they shall be visible without opening enclosure doors or covers. (1) Size. Transformers shall be rated at a minimum of 125 percent of the sum of the fire pump motors) and pres- (4) Controller Marking. A placard shall be placed adja- sure maintenance pump(s) motor loads, and 100 percent of cent to the fire pump controller, stating the location of this the remaining load supplied by the transformer. disconnecting means and the location of the key (if the disconnecting means is locked). (2) Overcurrent Protection. The transformer size, the feeder size, and the overcurrent protective device(s) shall (5) Supervision. The disconnecting means shall be su- he coordinated such that overcurrent protection is provided pervised in the closed position by one of the following for the transformer in accordance with 450.3 and for the methods: feeder in accordance with 2153, and such that the overcur- (t) Central station, proprietary, or remote station signal rent protective device(s) is selected or set to carry indefi- device nitely the sum of the locked-rotor current of the fire pump (2) Local signaling service that causes the sounding of an motor(s),the pressure maintenance pump motor(s),the full- audible signal at a constantly attended point load current of the associated fire pump accessory equip- (3) Locking the disconnecting means in the closed position ment, and 100 percent of the remaining loads supplied by (4) Sealing of disconnecting means and approved weekly the transformer. The requirement to carry the locked-rotor recorded inspections when the disconnecting means are currents indefinitely shall not apply to conductors or de- located within fenced enclosures or in buildings under vices other than overcurrent devices in the fire pump motor the control of the owner [20:9.2.3.31 circuit(s). 695.5 Transformers. Where the service or system voltage 695.6 Power Wiring. Power circuits and wiring methods is different from the utilization voltage of the fire pump shall comply with the requirements in 695.6(A) through motor, transformer(s) protected by disconnecting means (H), and as permitted in 230.90(A), Exception No. 4; 2008 Edition NATIONAL ELECTRICAL CODE 70-593 695.7 ARTICLE 695—FIRE PUMPS 230.94, Exception No. 4: 240.13; 230.208; 240.4(A); and (2) Fire Pump Motors Only.Conductors supplying only a 430.31. fire pump motor shall have a minimum ampacity in accor- dance with 430.22 and shall comply with the voltage drop (A) Service Conductors. Supply conductors shall be requirements in 695.7. physically routed outside a building(s) and shall be in- stalled as service-entrance conductors in accordance with (D) Overload Protection. Power circuits shall not have 230.6, 230.9, and Parts III and IV of Article 230. Where automatic protection against overloads. Except for protec- supply conductors cannot be physically routed outside tion of transformer primaries provided in 695.5(C)(2), buildings, they shall be permitted to be routed through branch-circuit and feeder conductors shall be protected buildings where installed in accordance with 230.6(1) or against short circuit only. Where a tap is made to supply a (2). Where a fire pump is wired under the provisions of fire pump, the wiring shall be treated as service conductors 695.3(B)(2), this requirement shall apply to all supply con- in accordance with 230.6. The applicable distance and size ductors on the load side of the service disconnecting means restrictions in 240.21 shall not apply, that constitute the normal source of supply to that fire Exception No. 1: Conductors between storage batteries pump. and the engine shall not require overcurrent protection or Exception: Where there are multiple sources of supply with disconnecting means. means for automatic connection front one source to the Exception No. 2: For art-.site standby generator(s) rated to other, the requirement shall apply only to those conductors produce continuous current in excess of 225 percent of the on the load side of that point of automatic connection be- !f amperes of the fire pump motor, the conductors tween sources. between the on-site generator(s) and the combination fire (B) Circuit Conductors. Fire pump supply conductors on pump transfer switch controller or separately mounted the load side of the final disconnecting means and overcur- transfer switch shall be installed in accordance with rent device(s) permitted by 695.4(B) shall be kept entirely 695.6(B). The protection provided shall be in accordance independent of all other wiring. They shall supply only with the short-circuit current rating of the combination fire loads that are directly associated with the fire pump system, pump transfer switch controller or separately mounted and they shall be protected to resist potential damage by transfer switch. fire,structural failure,or operational accident.They shall be (E) Pump Wiring. All wiring from the controllers to the permitted to be routed through a building(s) using one of pump motors shall be in rigid metal conduit, intermediate the following methods: metal conduit, liquidtight flexible metal conduit, or liq- (1) Be encased in a minimum 50 mm (2 in.) of concrete uidtight flexible nonmetallic conduit Type LFNC-B, listed (2) Be protected by a fire-rated assembly listed to achieve Type MC cable with an impervious covering, or Type MI a minimum fire rating of 2 hours and dedicated to the cable. fire pump circuit(s). (3) Be a listed electrical circuit protective system with a (F) Junction Points. Where wire connectors are used in minimum 2-hour fire rating the fire pump circuit, the connectors shall be listed. A fire pump controller or fire pump power transfer switch, where FIRM UL guide information for electrical circuit protective provided, shall not be used as a junction box to supply systems(FHIT)contains information on proper installation other equipment,including a pressure maintenance(jockey) requirements to maintain the fire rating. pump(s).A fire pump controller and fire pump power trans- Exception: The supply conductors located in the electrical fer switch, where provided, shall not serve any load other equipment room where they originate and in the fire pump than the fire pump for which it is intended. room shall not be required to have the minimum 1-hourfire separation or fire resistance rating, unless otherwise re- (C) Mechanical Protection. All wiring from engine con- separation by 700.9(D) of this Code. trolleys and batteries shall be protected against physical damage and shall be installed in accordance with the con- (C) Conductor Size. troller and engine manufacturer's instructions. (1) Fire Pump Motors and Other Equipment. Conduc- (H) Ground-Fault Protection of Equipment. Ground- tors supplying a fire pump motor(s), pressure maintenance fault protection of equipment shall not be permitted for fire pumps, and associated fire pump accessory equipment shall pumps. have a rating not less than 125 percent of the sum of the fire pump motor(s) and pressure maintenance motor(s) full-load 695.7 Voltage Drop.The voltage at the controller line ter- current(s), and 100 percent of the associated fire pump ac- minals shall not drop more than 15 percent below normal cessory equipment. (controller-rated voltage) under motor starting conditions. 70-594 NATIONAL ELECTRICAL CODE 2008 Edition ARTICL&695—FIRE PUMPS 695.14 The voltage at the motor terminals shall not drop more than ing of the wires, or loss of power to these circuits could 5 percent below the voltage rating of the motor when the cause continuous running of the fire pump but shall not motor is operating at 115 percent of the full-load current prevent the controller(s) from starting the fire pump(s) due rating of the motor. to causes other than these external control circuits.All con- Exception: This limitation shall not apply for emergency [to] conductors within the fire pump room that are not fault run mechanical starting. [20.9.4.2] tolerant shall be protected against physical damage. [20:10.5.2.6, 12.5.2.51 695.10 Listed Equipment. Diesel engine fire pump con- trollers, electric fire pump controllers, electric motors, fire (B) Sensor Functioning. No undervoItage, phase-loss, pump power transfer switches, foam pump controllers, and Frequency-sensitive, or other sensor(s) shall be installed limited service controllers shall be listed for fire pump ser- that automatically or manually prohibits actuation of the vice. [20:9.5.1.1, 10.1.2.1, 12.1.3.11 motor contactor. [20:10.4.5.6] Exception: A phase loss sensor(s) shall be permitted only 695.12 Equipment Location. as a part of a listed fire punip controller. (A) Controllers and Transfer Switches. Electric motor- driven fire pump controllers and power transfer switches (Cl Remote Device(s). No remote device(s) shall be in- shall be located as close as practicable to, and within sight stalled that will prevent automatic operation of the transfer of, the motors that they control. switch. [20:10.8.1.3] (B) Engine-Drive Controllers. Engine-drive fire pump (D) Engine-Drive Control Wiring. All wiring between controllers shall be located as close as is practical to, and the controller and the diesel engine shall be stranded and within sight of, the engines that they control. sized to continuously carry the charging or control currents as required by the controller manufacturer. Such wiring (C) Storage Batteries. Storage batteries for fire pump en- shall be protected against physical damage. Controller gine drives shall be supported above the floor, secured manufacturer's specifications for distance and wire size against displacement, and located where they are not sub- shall be followed. 120:12.3.5.1] ject to physical damage, flooding with water, excessive temperature, or excessive vibration. (E) Electric Fire Pump Control Wiring Methods. All electric motor—driven fire pump control wiring shall be in (D) Energized Equipment. All energized equipment parts rigid metal conduit, intermediate metal conduit, liquidtight shall be located at least 300 mm (12 in,) above the floor flexible metal conduit, liquidtight flexible nonmetallic con- level, duit Type B (UNGB), listed Type MC cable with an im- (E) Protection Against Pump Water. Fire pump control- pervious covering, or Type MI cable. ler and power transfer switches shall be located or pro- tected so that they are not damaged by water escaping from (F) Generator Control Wiring Methods. Control con- pumps or pump connections. ductors installed between the fire pump power transfer switch and the standby generator supplying the fire pump (F) Mounting. All fire pump control equipment shall be during normal power loss shall be kept entirely independent mounted in a substantial manner on noncombustible sup- of all other wiring. They shall be protected to resist poten- porting structures. tial damage by fire or structural failure. They shall be per- mitted to be routed through a building(s) encased in 50 mm 695.14 Control Wiring. (2 in,) of concrete or within enclosed construction dedi- (A) Control Circuit Failures. External control circuits cated to the fire pump circuits and having a minimum that extend outside the fire pump room shall be arranged so 1-hour fire resistance rating, or circuit protective systems that failure of any external circuit (open or short circuit) with a minimum of ]-hour fire resistance. The installation shall not prevent the operation of a pump(s) from all other shall comply with any restrictions provided in the listing of internal or external means. Breakage, disconnecting, short- the electrical circuit protective system used. 2008 Edition NATIONAL ELECTRICAL CODE 70-595 CHAPTER 7 ARTICLE 700—EMERGENCY SYSTEMS Chapter 7 Special Conditions 700.4 Tests and Maintenance. ARTICLE 700 Emergency Systems (A) Conduct or Witness Test.The authority having juris- diction shall conduct or witness a test of the complete sys- tem upon installation and periodically afterward. 1. General (B) Tested Periodically. Systems shall be tested periodi- 700.1 Scope. The provisions of this article apply to the cally on a schedule acceptable to the authority having ju- electrical safety of the installation, operation, and mainte- risdiction to ensure the systems are maintained in proper nance of emergency systems consisting of circuits and operating condition. equipment intended to supply, distribute, and control elec- tricity for illumination, power,or both,to required facilities (C) Battery Systems Maintenance. Where battery sys- when the normal electrical supply or system is interrupted. tems or unit equipments are involved, including batteries Emergency systems are those systems legally required used for starting, control, or ignition in auxiliary engines, and classed as emergency by municipal, state, federal, or the authority having jurisdiction shall require periodic other codes, or by any governmental agency having juris- maintenance. diction.These systems are intended to automatically supply illumination, power, or both, to designated areas and equip- (D) Written Record. A written record shall be kept of ment in the event of failure of the normal supply or in the such tests and maintenance. event of accident to elements of a system intended to sup- ply, distribute, and control power and illumination essential (E} Testing Under Load. Means for testing all emergency for safety to human life. lighting and power systems during maximum anticipated load conditions shall be provided. FPN No. I: For further information regarding wiring and installation of emergency systems in health care facilities, FPN: For testing and maintenance procedures of emer- see Article 517. gency power supply systems(EPSSs),see NFPA 110-2005, FPN No.2: For further information regarding performance Standard for Emergency and Standby Power Systems. and maintenance of emergency systems in health care fa- cilities, see NFPA 99-2005, Standard for Health Care 700.5 Capacity. Facilities. (A) Capacity and Rating. An emergency system shall FPN No. 3: Emergency systems are generally installed in or safe of assembly where artificial illumination is required have adequate capacity and rating for all loads to be oper- f for safe exiting and for panic control in buildings subject to ated simultaneously. The emergency system equipment occupancy by large numbers of persons, such as hotels, shall be suitable for the maximum available fault current at theaters, sports arenas, health care facilities, and similar its terminals. institutions. Emergency systems may also provide power for such functions as ventilation where essential to maintain (B) Selective Load Pickup, Load Shedding, and Peak life,fire detection and alarm systems,elevators,fire pumps, Load Shaving.The alternate power source shall be permit- public safety communications systems,industrial processes ted to supply emergency, le all y required standby, and op- where current interruption would produce serious life safety or health hazards, and similar functions, tional standby system loads where the source has adequate capacity or where automatic selective load pickup and load gency lighting is considered essential to life safely, see FPN No. 4: For specification locations where emer- shedding is provided as needed to ensure adequate power to NFPA 101 -2006,Life Safety Code*. (1) the emergency circuits, (2) the legally required standby FPN No.5: For further information regarding performance circuits, and (3) the optional standby circuits, in that order of emergency and standby power systems, see NFPA I10- of priority.The alternate power source shall be permitted to 2005,Standard for Emergency and Standby Power Systems. be used for peak load shaving, provided these conditions are met. 700.2 Application of Other Articles. Except as modified Peak load shaving operation shall be permitted for sat- by this article, all applicable articles of this Code shall isfying the test requirement of 700.4(B), provided all other apply. conditions of 700.4 are met. A portable or temporary alternate source shall be avail- 700.3 Equipment Approval. All equipment shall be ap- able whenever the emergency generator is out of service for proved for use on emergency systems. major maintenance or repair. 70-596 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 700—EMERGENCY SYSTEMS 700.9 700.6 'Eransfer Equipment. Exception: A sign shall not be required for individual unit (A) General. Transfer equipment, including automatic equipment as specified in 700.12(F). transfer switches, shall be automatic, identified for emer- (B) Grounding. Where the grounded circuit conductor gency use, and approved by the authority having jurisdic- connected to the emergency source is connected to a tion. Transfer equipment shall be designed and installed to grounding electrode conductor at a location remote from prevent the inadvertent interconnection of normal and the emergency source, there shall be a sign at the grounding emergency sources of supply in any operation of the trans- location that identifies all emergency and normal sources fer equipment. Transfer equipment and electric power pro- connected at that location. duction systems installed to permit operation in parallel with the normal source shall meet the requirements of Ar- ticle 705. II. Circuit Wiring (B) Bypass Isolation Switches. Means shall be permitted 700.9 Wiring, Emergency System. to bypass and isolate the transfer equipment. Where bypass (A) Identification. All boxes and enclosures (including isolation switches are used, inadvertent parallel operation transfer switches, generators, and power panels) for emer- shall be avoided. gency circuits shall be permanently marked so they will be (C) Automatic Transfer Switches. Automatic transfer readily identified as a component of an emergency circuit switches shall be electrically operated and mechanically or system. held. Automatic transfer switches, rated 600 VAC and be- (B) Wiring, Wiring of two or more emergency circuits Iow, shall be listed for emergency system use. supplied from the same source shall be permitted in the (D) Use. Transfer equipment shall supply only emergency same raceway,cable, box, or cabinet.Wiring from an emer- loads. gency source or emergency source distribution overcurrent protection to emergency loads shall be kept entirely inde- 700.7 Signals. Audible and visual signal devices shall be pendent of all other wiring and equipment, unless otherwise provided, where practicable, for the purpose described in permitted in (i) through (5): 700.7(A) through (D). (1) Wiring from the normal power source located in trans- fer equipment enclosures (A) Derangement. To indicate derangement of the emer- (2) Wiring supplied from two sources in exit or emergency gency source. luminaires (B) Carrying Load.To indicate that the battery is carrying (3) Wiring from two sources in a common junction box, load, attached to exit or emergency luminaires (4) Wiring within a common junction box attached to unit (C) Not Functioning. To indicate that the battery charger equipment, containing only the branch circuit supply- is not functioning. ing the unit equipment and the emergency circuit sup- (D) Ground Fault. To indicate a ground fault in solidly plied by the unit equipment grounded wye emergency systems of more than 150 volts (5) Wiring from an emergency source to supply any eom- to ground and circuit-protective devices rated 1000 am- bination Of emergency, legally required, or optional peres or more. The sensor for the ground-fault signal de- loads in accordance with (a), (b), and (c): vices shall be located at, or ahead of, the main system a. From separate vertical switchboard sections,with or disconnecting means for the emergency source, and the without a common bus, or from individual discon- maximum setting of the signal devices shall be for a nects mounted in separate enclosures. ground-fault current of 1200 amperes. Instructions on the b. The common bus or separate sections of the switch- course of action to be taken in event of indicated ground board or the individual enclosures shall be permitted fault shall be located at or near the sensor location, to be supplied by single or multiple feeders without FPN: For signals For generator sets, see NFPA 110-2005, overcurrent protection at the source. Standard for Emergency and Standby Power Systems. Exception to(5)(b):Overcurrent protection shall be permit- ted at the source or for the equipment, provided the over- 700.8 Signs. current protection is selectively coordinated with the down- (A) Emergency Sources. A sign shall be placed at the stream overcurrent protection. service-entrance equipment, indicating type and location of c. Legally required and optional Standby circuits shall on-site emergency power sources, not originate from the same vertical Switchboard 2008 Edition NATIONAL @L,ECTRICAL COIF: 74-597 700.12 ARTICLE 700--EMERGENCY SYSTEMS section, panelboard enclosure, or individual discon- within the time required for the application but not to ex- neet enclosure as emergency circuits. ceed 10 seconds. The supply system for emergency pur- poses,in addition to the normal services to the building and (C) Wiring Design and Location. Emergency wiring cir- meeting the general requirements of this section, shall be cults shall be designed and located so as to minimize the one or more of the types of systems described in 700.12(A) hazards that might cause failure due to flooding, fire, icing, through (E). Unit equipment in accordance with 704.12(F) vandalism, and other adverse conditions. shall satisfy the applicable requirements of this article. (D) Fire Protection. Emergency systems shall meet the In selecting an emergency source of power, consider- additional requirements in 700.9(D)(1) and (13)(2) in as- ation shall be given to the occupancy and the type of ser- sembly occupancies for not less than 1000 persons or in vice to be rendered, whether of minimum duration, as for buildings above 23 m (75 ft) in height with any of the evacuation of a theater, or longer duration, as for supplying following occupancy classes: assembly, educational, resi- emergency power and lighting due to an indefinite period dential, detention and correctional, business, and mercan- of current failure from trouble either inside or outside the tile, building. Equipment shall be designed and located so as to mini- (1) Feeder-Circuit Wiring. Feeder-circuit wiring shall mize the hazards that might cause complete failure due to meet one of the following conditions: flooding, fires, icing, and vandalism. (1) Be installed in spaces or areas that are fully protected Equipment for sources of power as described in by an approved automatic fire suppression system 700.12(A) through (E) where located within assembly oc- (2) Be a listed electrical circuit protective system with a cupancies for greater than 1000 persons or in buildings minimum 1-hour fire rating above 23 m (75 ft) in height with any of the following occupancy classes — assembly, educational, residential, FPN: UL guide information for electrical circuit protec- detention and correctional, business, and mercantile — tion systems(FHIT)contains information on proper instal- shall be installed either in spaces full protected b a lation requirements to maintain the fire rating. P Y P Y P- (3) Be protected by a listed thermal barrier system for elec- Proved automatic fire suppression systems (sprinklers, car- trica] system components bon dioxide systems, and so forth) or in spaces with a (4) Be protected by a listed fire-rated assembly that has a 1-hour fire rating. minimum fire rating of 1-hour and contains only ewer- FPN No. 1: For the definition of Occupancy Classification, gency wiring circuits. see Section 6.1 of NFPA 101-2006, Life Safety Code. (5) Be embedded in not less than 50 mm(2 in.)of concrete FPN No. 2: Assignment of degree of reliability of the rec- ognized emergency supply system depends on the careful (b) Be a cable listed to maintain circuit integrity for not evaluation of the variables at each particular installation. less than 1 hour when installed in accordance with the listing requirements (A) Storage Battery. Storage batteries used as a source of (2) Feeder-Circuit Equipment. Equipment for feeder cir- power for emergency systems shall be of suitable rating and cuits (including transfer switches, transformers, and panel- capacity to supply and maintain the total load for a mini- boards) shall be located either in spaces fully protected by mum period of 11/2 hours, without the voltage applied to the approved automatic fire suppression systems (including load falling below 871/2 percent of normal. sprinklers, carbon dioxide systems) or in spaces with a Batteries, whether of the acid or alkali type, shall be ]-hour fire resistance rating. designed and constructed to meet the requirements of emer- gency service and shall be compatible with the charger for FPN: For the definition of Occupancy Classification, see that particular installation. Section 6.I of NFPA 101-2006, Life Safety Code. For a sealed battery, the container shall not be required (3) Generator Control Wiring. Control conductors in- to be transparent. However, for the lead acid battery that re- stalled between the transfer equipment and the emergency quires water additions, transparent or translucent jars shall be generator shall be kept entirely independent of all other furnished.Automotive-type batteries shall not be used. wiring and shall meet the conditions of 700.9(D)(1). An automatic battery charging means shall be provided. (B) Generator Set. III. Sources of Power (1) Prime Mover-Driven. For a generator set driven by a 700.12 General Requirements. Current supply shall be prime mover acceptable to the authority having jurisdiction such that, in the event of failure of the normal supply to, or and sized in accordance with 700.5, means shall be pro- within, the building or group of buildings concerned, emer- vided for automatically starting the prime mover on fail- gency lighting,emergency power, or both shall be available ure of the normal service and for automatic transfer and 70-598 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 700—EMERGENCY SYSTEMS 700.12 operation of all required electrical circuits. A time-delay shall be in accordance with the applicable provisions of Article feature permitting a 15-minute setting shall be provided 230 and the following additional requirements: to avoid retransfer in case of short-time reestablishment (1) Separate service drop or service lateral of the normal source, (2) Service conductors sufficiently remote electrically and (2) Internal Combustion as Prime Movers. Where inter- physically from any other service conductors to mini- nal combustion engines are used as the prime mover, an mize the possibility of simultaneous interruption of on-site fuel supply shall be provided with an on-premise supply fuel supply sufficient for not less than 2 hours' full-demand operation of the system, Where power is needed for the (E) Fuel Cell System. Fuel cell systems used as a source operation of the fuel transfer pumps to deliver fuel to a of power for emergency systems shall be of suitable rating generator set day tank, this pump shall be connected to the and capacity to supply and maintain the total load for not emergency power system. less than 2 hours of full-demand operation. Installation of a fuel cell system shall meet the require- (3) Dual Supplies. Prime movers shall not be solely de- menu of Parts ❑ through VIII of Article 692. pendent on a public utility gas system for their fuel supply Where a single fuel cell system serves as the normal or municipal water supply for their cooling systems. Means supply For the building or group of buildings concerned, it shall be provided for automatically transferring from one fuel supply to another where dual fuel supplies are used. shall not serve as the sole source of power for the emer- gency standby system. Exception: Where acceptable to the authority having juris- diction, the use of other than on-site fuels shall be permit- (F) Unit Equipment. Individual unit equipment for emer- red where there is a low probability of a simultaneous fail- gency illumination shall consist of the following: ure of both the off site fuel deliven,system and power from (1) A rechargeable battery the outside electrical utility company. (2) A battery charging means (4) Battery Power and Dampers.Where a storage battery (3) Provisions for one or more lamps mounted on the is used for control or signal power or as the means of equipment, or shall be permitted to have terminals for starting the prime mover, it shall be suitable for the purpose remote lamps, or both and shall be equipped with an automatic charging means (4) A relaying device arranged to energize the lamps auto- independent of the generator set. Where the battery charger matically upon failure of the supply to the unit is required for the operation of the generator set, it shall be equipment connected to the emergency system. Where power is re- quired for the operation of dampers used to ventilate the The batteries shall be of suitable rating and capacity to generator set, the dampers shall be connected to the emer- supply and maintain at not less than $711: percent of the gency system. nominal battery voltage for the total lamp load associated with the unit for a period of at least 11/2 hours, or the unit (5) Auxiliary Power Supply. Generator sets that require equipment shall supply and maintain not less than 60 per- more than 10 seconds to develop power shall be permitted cent of the initial emergency illumination for a period of at if an auxiliary power supply energizes the emergency sys- least 11/ hours. Storage batteries, whether of the acid or tem until the generator can pick up the load. alkali type, shall be designed and constructed to meet the (6) Outdoor Generator Sets. Where an outdoor housed requirements of emergency service. generator set is equipped with a readily accessible discon- Unit equipment shall be permanently fixed in place necting means located within sight of the building or struc- (i.e., not portable) and shall have all wiring to each unit ture supplied, an additional disconnecting means shall not installed in accordance with the requirements of any of the be required where ungrounded conductors serve or pass wiring methods in Chapter 3. Flexible card-and-plug con- through the building or structure. The disconnecting means nection shall be permitted, provided that the cord does not Shall meet the requirements of 225.36. exceed 900 mm (3 ft) in length. The branch circuit feeding the unit equipment shall be the same branch circuit as that (C) Uninterruptible Power Supplies. Uninterruptible serving the normal lighting in the area and connected ahead power supplies used to provide power for emergency sys- of any local switches. The branch circuit that feeds unit terns shall comply with the applicable provisions of 700.12(A) and (B). equipment shall be clearly identified at the distribution panel. Emergency luminaires that obtain power from a unit (D) Separate Service. Where approved by the authority equipment and are not part of the unit equipment shall be having jurisdiction as suitable for use as an emergency source wired to the unit equipment as required by 700.9 and by of power,an additional service shall be permitted.This service one of the wiring methods of Chapter 3. 2008 Edition NATIONAL ELECTRICAL CODE 70--599 700.15 ARTICLE 700—EMERGENCY SYSTEMS Exception: In a separate and uninterrupted area supplied shall be an emergency supply source to which the load will by a minimum of three normal lighting circuits, a separate be transferred automatically upon the failure of the normal branch circuit for runt equipment shall be permitted if it supply. originates from the same panelboard as that of the normal lighting circuits and is provided with a lock-on feature. V. Control —Emergency Lighting Circuits 700.20 Switch Requirements. The switch or switches in- IV. Emergency System Circuits for Lighting and stalled in emergency lighting circuits shall be arranged so Power that only authorized persons have control of emergency 700.15 Loads on Emergency Branch Circuits. No appli- lighting. ances and no lamps, other than those specified as required Exception No. 1: Where two or more single-throw switches for emergency use, shall be supplied by emergency lighting are connected in parallel to control a single circuit, at least circuits. one of these switches shall be accessible only to authorized persons. 700.16 Emergency Illumination. Emergency illumination Exception No. 2: Additional switches that act only to put shall include all required means of egress lighting, illumi- emergency lights into operation but nor disconnect them nated exit signs, and all other lights specified as necessary shall be permissible. to provide required illumination. Emergency lighting systems shall be designed and in- Switches connected in series or 3- and 4-way switches stalled so that the failure of any individual lighting element, shall not be used. such as the burning out of a lamp, cannot Ieave in total darkness any space that requires emergency illumination. 700.21 Switch Location. All manual switches for control- Where high-intensity discharge lighting such as high- ling emergency circuits shall be in locations convenient to and law-pressure sodium, mercury vapor, and metal halide authorized persons responsible for their actuation. In facili- is used as the sole source of normal illumination, the emer- ties covered by Articles 518 and 520, a switch for control- gency lighting system shall be required to operate until ling emergency lighting systems shall be located in the normal illumination has been restored. lobby or at a place conveniently accessible thereto. In no case shall a control switch for emergency lighting Exception: Alternative nneans that ensure emergency light- be placed in a motion-picture projection booth or on a stage ing illumination level is maintained shall be permitted. or platform. 700.17 Circuits for Emergency Lighting. Branch circuits Exception: Where multiple switches are provided, one such that supply emergency lighting shall be installed to provide switch shall be permitted in such locations where arranged service from a source complying with 700.12 when the so that it can only energize the circuit but cannot de- normal supply for lighting is interrupted. Such installations energize the circuit. shall provide either of the following: 700.22 Exterior Lights. Those lights on the exterior of a (1) An emergency lighting supply, independent of the gen- building that are not required for illumination when there is eral lighting supply, with provisions for automatically sufficient daylight shall be permitted to be controlled by an transferring the emergency lights upon the event of automatic light-actuated device. failure of the general lighting system supply (2) Two or more separate and complete systems with rode- 7Q0.23 Dimmer System.. A dimmer System Containing pendent power supply, each system providing sufficient more than one dimmer and listed for use in emergency current for emergency lighting purposes systems shall be permitted to be used as a control device for energising emergency lighting circuits. Upon failure of Unless both systems are used for regular lighting pur- normal power, the dim,mer System shall be permitted to poses and are both kept lighted, means shall be provided selectively energize only those branch circuits required to for automatically energizing either system upon failure of provide minimum emergency 'illumination. All branch cir the other. Either or both systems shall be permitted to be a cuits supplied by the dimmer system cabinet shal comply part of the general lighting system of the protected occu- with the wiring methods of Article 700. pancy if circuits supplying lights for emergency illumina- tion are installed in accordance with other sections of this VI. Overcurrent Protection article. 700.25 Accessibility. The branch-circuit overcurrent de- 700.I8 Circuits for Emergency Power. For branch cir- vices in emergency circuits shall be accessible to autho- cuits that supply equipment classed as emergency, there rized persons only. 70-600 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 701 LEGALLY REQUIRED STANDBY SYSTEMS 701.6 700.26 Ground-Fault Protection of Equipment. The al- those classed as emergency systems) in the event of failure ternate source for emergency systems shall not be required of the normal source. to have ground-fault protection of equipment with auto- matic disconnecting means. Ground-fault indication of the FPN: Legally required standby systems are typically in- stalled to serve loads, such as heating and refrigeration emergency source shall be provided per 700.7(D), systems, communications systems, ventilation and smoke removal systems, sewage disposal, lighting systems, and 700.27 Coordination. Emergency system(s) overcurrent industrial processes, that, when stopped during any inter- devices shall be selectively coordinated with all supply side ruption of the normal electrical supply,could create hazards overcurrent protective devices. or hamper rescue or fire-fighting operations. E.rception: Selective Coordination shall not be required in 701.3 Application of Other Articles. Except as modified (1) or(2): by this article, all applicable articles of this Code shall apply. (1) Between transformer primary and secondary overcur- rent protective devices, where only one overcurrent 701.4 Equipment Approval. All equipment shall be ap- protective device or set of overcurrent protective de- proved for the intended use. vices exists on the transformer secondary, 701.5 Tests and Maintenance for Legally Required (2) Between overcurrent protective devices of the same size Standby Systems. (ampere rating) in series. (A) Conduct or Witness Test. The authority having juris- diction shall conduct or witness a test of the complete sys- tem upon installation. ARTICLE 701 (B) Tested Periodically. Systems shall be tested periodi- Legally Required Standby Systems cally on a schedule and in a manner acceptable to the au- thority having jurisdiction to ensure the systems are main- tained in proper operating condition. I. General (C) Battery Systems Maintenance. Where batteries are 701.1 Scope. The provisions of this article apply to the used for control, starting, or ignition of prime movers, electrical safety of the installation, operation, and mainte- the authority having jurisdiction shall require periodic nance of legally required standby systems consisting of cir- maintenance. cuits and equipment intended to supply, distribute,and con- trol electricity to required facilities for illumination or (D) Written Record. A written record shall be kept on power,or both, when the normal electrical supply or system such tests and maintenance. is interrupted. (E) Testing Under Load. Means for testing legally re- The systems covered by this article consist only of quired standby systems under load shall be provided. those that are permanently installed in their entirety, includ- ing the power source. FPN: For testing and maintenance procedures of emer- gency power supply systems(EPSSs),see NFPA 110-2005, FPN No. 1: For additional information,see NFPA 99-2005, Standard for Emergency and Standby Power Systems. Standard for Health Care Facilities. FPN No. 2: For further information regarding performance 701.6 Capacity and Rating. A legally required standby of emergency and standby power systems, see NFPA 110- system shall have adequate capacity and rating for the sup- 2005.Standard_fnr Emergency and Standby Power Systems, ply of all equipment intended to be operated at one time. FPN No. 3: For further information, see ANSUIEEE 446- Legally required standby system equipment shall be suitable 1995, Recommended Practice for Eme rgeney and Standby for the maximum available fault current at its terminals. Power Systems for Industrial and Commercial The legally required standby alternate power source Applications. shall be permitted to supply both legally required standby and optional standby system loads under either of the fol- 701.2 Definition. lowing conditions: Legally Required Standby Systems. Those systems re- (1) Where the alternate source has adequate capacity to quired and so classed as legally required standby by mu- handle all connected loads nicipal, state, federal, or other codes or by any governmen- (2) Where automatic selective load pickup and load shed- tal agency having jurisdiction. These systems are intended ding is provided that will ensure adequate power to the to automatically supply power to selected loads (other than legally required standby circuits 2008 Edition NATIONAL ELECTRICAL CODE 70-601 701.7 ARTICLE 701—LEGALLY REQUIRED STANDBY SYSTEMS 701.7 Transfer Equipment. occupy the same raceways,cables,boxes, and cabinets with (A) General. Transfer equipment, including automatic other general wiring. transfer switches, shall be automatic and identified for standby use and approved by the authority having jurisdic- III. Sources of Power Lion. Transfer equipment shall be designed and installed to prevent the inadvertent interconnection of normal and alter- 701.11 Legally Required Standby Systems. Current sup- nate sources of supply in any operation of the transfer PIY shall be such that, in the event of failure of the norms[ equipment.Transfer equipment and electric power production supply to, or within, the building or group of buildings systems installed to permit operation in parallel with the nor- concerned, legally required standby power will be available mal source shall meet the requirements of Article 705. within the time required for the application but not to ex- ceed 60 seconds. The supply system for legally required (B) Bypass isolation Switches. Means to bypass and iso- standby purposes, in addition to the normal services to the late the transfer switch equipment shall be permitted. building, shall be permitted to comprise one or more of the Where bypass isolation switches are used, inadvertent par- types of systems described in 701.11(A) through (F). Unit alleI operation shall be avoided. equipment in accordance with 701.]1(G) shall satisfy the applicable requirements of this article. (C) Automatic Transfer Switches. Automatic transfer In selecting a legally required standby source of power, switches shall be electrically operated and mechanically consideration shall be given to the type of service to be held. Automatic transfer switches, rated 600 VAC and be- rendered, whether of short-time duration or long duration. low,Shall be listed for legally required standby System use. Consideration shall be given to the location or design, 701.8 Signals. Audible and visual signal devices shall be or both, of all equipment to minimize the hazards that provided, where practicable, for the purposes described in might cause complete failure due to floods, fires, icing, and 701.8(8), (B), and (C). vandalism. FPN: Assignment of degree of reliability of the recognized (A) Derangement.To indicate derangement of the standby legally required standby supply system depends on the source, careful evaluation of the variables at each particular installation. (B) Carrying Load.To indicate that the standby source is carrying load. (A) Storage Battery. A storage battery shall be of suitable rating and capacity to supply and maintain at not less than (C} Not Functioning. To indicate that the battery charger 871/2 percent of system voltage the total load of the circuits is not functioning. supplying legally required standby power for a period of at FPN: For signals for generator sets, see NFPA 110-2005, least 11/2 hours. Standard for Elnergenc.v and Standby Power Systems. Batteries, whether of the acid or alkali type, shall be designed and constructed to meet the service requirements 701.9 Signs. of emergency service and shall be compatible with the (A) Mandated Standby. A sign shall be placed at the ser- charger for that particular installation. vice entrance indicating type and location of on-site legally For a scaled battery, the container shall not be required required standby power sources. to be transparent. However, for the lead acid battery that requires water additions, transparent or translucent jars Exception: A sign shall not he required for individual unit shall be furnished. Automotive-type batteries shall not be equipment as specified in 701.11(G). used. (B) Grounding. Where the grounded circuit conductor An automatic battery charging means shall be provided. connected to the legally required standby power source is (B) Generator Set. connected to a grounding electrode conductor at a location remote from the legally required standby power source, (1) Prime Mover-Driven. For a generator set driven by a there shall be a sign at the grounding location that shall prime mover acceptable to the authority having jurisdiction identify all legally required standby power and normal and sized in accordance with 701.6, means shall be pro- sources connected at that location. vided for automatically starting the prime mover upon fail- ure of the normal service and for automatic transfer and operation of all required electrical circuits. A time-delay lI. Circuit Wiring feature permitting a I5-minute setting shall be provided to 701.10 Wiring Legally Required Standby Systems. The avoid retransfer in case of short-time re-establishment of legally required standby system wiring shall be permitted to the normal source. 70-602 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 701 --LEGALLY REQUIRED STANDBY SYSTEMS 701.15 (2) Internal Combustion Engines as Prime Mover. (F) Fuel Cell System. Fuel cell systems used as a source Where internal combustion engines are used as the prime of power for legally required standby systems shall be of mover, an on-site fuel supply shall be provided with an suitable rating and capacity to supply and maintain the total on-premises fuel supply sufficient for not less than 2 hours" load for not less than 2 hours of full-demand operation. full-demand operation of the system. Installation of a fuel cell system shall meet the require- (3) Dual Fuel Supplies. Prime movers shall not be solely ments of Parts 11 through VIII of Article 692. dependent on a public utility gas system for their fuel supply Where a single fuel cell system serves as the normal or on a municipal water supply for their cooling supply for the building or group of buildings concerned, it p pp y g systems. shall not serve as the sole source of power for the legally Means shall be provided for automatically transferring one fuel supply to another where dual fuel supplies are used. required standby system. Exception: Where acceptable to the authority having juris- (G) Unit Equipment. Individual unit equipment for legally diction, the use of other than on-site fuels shall be permit- required standby illumination shall consist of the following: ted where there is a low probability of a simultaneous fail- (1) A rechargeable battery tare of both the of-site fuel delivery system and power from (2) A battery charging means the outside electrical utility company. (3) Provisions for one or more lamps mounted on the (4) Battery Power. Where a storage battery is used for equipment and shall be permitted to have terminals for control or signal power or as the means of starting the remote lamps prime mover, it shall be suitable for the purpose and shall (4) A relaying device arranged to energize the lamps auto- be equipped with an automatic charging means independent matically upon failure of the supply to the unit of the generator set, equipment (5) Outdoor Generator Sets. Where an outdoor housed The batteries shall be of suitable rating and capacity to generator set is equipped with a readily accessible diccon- supply and maintain at not less than 871/z percent of the necting means located within sight of the building or struc- nominal battery voltage for the total lamp load associated ture supplied, an additional disconnecting means shall not with the unit for a period of at least 11/2 hours, or the unit be required where ungrounded conductors serve or pass equipment shall supply and maintain not less than 60 per- through the building or structure. The disconnecting means cent of the initial legally required standby illumination for a shall meet the requirements of 225.36. period of at least 11/2 hours. Storage batteries, whether of the acid or alkali type, shall be designed and constructed to (C) Uninterruptible Power Supplies. Uninterruptible meet the requirements of emergency service. power supplies used to provide power for legally required Unit equipment shall be permanently fixed in place standby systems shall comply with the applicable provi- (i.e., not portable) and shall have all wiring to each unit sions of 701.11(A) and (B), installed in accordance with the requirements of any of the {D} Separate Service. Where approved, a separate service Firing methods in Chapter 3. Flexible cord-and-plug con- nection shall be permitted, provided that the cord does not shall be permitted as a legally required source of standby exceed 900 mm (3 ft) in length. The branch circuit feeding power. This service shall be in accordance with the appli- the unit equipment shall be the same branch circuit as that cable provisions of Article 230, with separate service drop serving the normal lighting in the area and connected ahead or lateral sufficiently remote electrically and physically of any local switches. Legally required standby luminaires from any other service to minimize the possibility of simul- taneous interruption of supply from an occurrence in an- that obtain power from a unit equipment and are not part of the unit equipment steal] be wired to the unit equipment by other service. one of the wiring methods of Chapter 3. (E) Connection Ahead of Service Disconnecting Means. Exception: In a separate and uninterrupted area supplied Where acceptable to the authority having jurisdiction, con- by a minimum of three normal lighting circuits, a separate nections located ahead of and not within the same cabinet, branch circuit for unit equipment shall be permitted if it enclosure, or vertical switchboard section as the service originates from the same panelboard as that of the normal disconnecting means shall be permitted. The legally re- lighting circuits and is provided with it lock-on feature. quired standby service shall be sufficiently separated from the normal main service disconnecting means to prevent simultaneous interruption of supply through an occurrence TV. Overcurrent Protection within the building or groups of buildings served. 701.15 Accessibility. The branch-circuit overcurrent de- FPN: See 230.82 for equipment permitted on the supply vices in legally required standby circuits shall be accessible side of a service disconnecting means. to authorized persons only, 2008 Edition NATIONAL ELECTRICAL CODE 70-603 701.17 ARTICLE 702--OPTIONAL STANDBY SYSTEMS 701.17 Ground-Fault Protection of Equipment. The a]- 702.5 Capacity and Rating. ternate source for legally required standby systems shall not be required to have ground-fault protection of equipment. (A) Available Short-Circuit Current. Optional standby system equipment shall be suitable for the maximum avail- 701.18 Coordination. Legally required standby system(s) able short-circuit current at its terminals, overcurrent devices shall be selectively coordinated with all (B) System Capacity. The calculations of load on the supply side overcurrent protective devices. standby source shall he made in accordance with Article Exception: Selective coordination shall not be required in 220 or by another approved method. (1) or(2): (1) Manual Transfer Equipment. Where manual transfer equipment is used, an optional standby system shall have (1) Between transformer primary and secondary ave►�cur- adequate capacity and rating for the Supply of all equip- rent protective devices, where only one overcurrent went intended to be operated at one time. The user of the protective device or set of overcurrent protective de- optional standby system shall be permitted to select the vices exists on the transformer secondary, load connected to the system. (2) Between overcurrentprotective devices of the same size (ampere rating) in series. (2) Automatic Transfer Equipment. Where automatic transfer equipment i5 used, an optional standby system shall comply with (2)(a) or(2)(b). (a) Full,Load. The standby source shall be capable of ARTICLE 702 supplying the full load that is transferred by the automatic Optional Standby Systems transfer equipment. (b) .Load Management. Where a system is employed that will automatically manage the connected load, the I. General standby source shall have a capacity sufficient to supply the 702.1 Scope. The provisions of this article apply to the maximum load that will be connected by the load manage- ment system. installation and operation of optional standby systems. The systems covered by this article consist of those that 702.6 Transfer Equipment. Transfer equipment shall be are permanently installed in their entirety, including prime suitable for the intended use and designed and installed so movers, and those that are arranged for a connection to a as to prevent the inadvertent interconnection of normal and premises wiring system from a portable alternate power alternate sources of supply in any operation of the transfer supply. equipment.Transfer equipment and electric power production systems installed to permit operation in parallel with the nor- 702.2 Definition. mat source shall meet the requirements of Article 705. Optional Standby Systems. Those systems intended to Transfer equipment, located on the load side of branch supply power to public or private facilities or property circuit protection, shall be permitted to contain supplemen- where life safety does not depend on the performance of the tal overcurrent protection having an interrupting rating suf- system. Optional standby systems are intended to supply ficient for the available fault current that the generator can on-site generated power to selected loads either automati- deliver. The supplementary overcurrent protection devices cally or manually. shall be part of a listed transfer equipment. Transfer equipment shall be required for all standby FPN: Optional standby systems are typically installed to systems subject to the provisions of this article and for provide an alternate source of electric power for such fa- which an electric utility supply is either the normal or cilities as industrial and commercial buildings, farms, and residences and to serve loads such as heating and refrigera- standby source. tion systems,data processing and communications systems, Exception: Temporary connection of a portable generator and industrial processes that,when stopped during any power outage, could cause discomfort, serious interruption of the without transfer equipment shall be permitted where condi- process, damage to the product or process,or the like, tions of maintenance and supervision ensure that only qualified persons service the installation and where the 702.3 Application of Other Articles. Except as modified normal supply is physically isolated by a lockable discon- by this article, all applicable articles of this Code shall necting means or by disconnection of the normal supply apply. conductors. 702.4 Equipment Approval. All equipment shall be ap- 702.7 Signals. Audible and visual signal devices shall be proved for the intended use. provided, where practicable, for the following purposes. 70-664 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 705—INTERCONNECTED ELECTRIC POWER PRODUCTION SOURCES 705.10 (1) Derangement.To indicate derangement of the optional standby source. ARTICLE 705 (2) Carrying Load. To indicate that the optional standby Interconnected Electric Power source is carrying load. Production Sources EA:eeption: Signals shall not be required for portable 1. General standby power sources. 705.1 Scope.This article covers installation of one or more 702.8 Signs. electric power production sources operating in parallel with (A) Standby.A sign shall be placed at the service-entrance a primary source(s) of electricity. equipment that indicates the type and location of on-site FPN: Examples of the types of primary sources include a optional standby power sources. A sign shall not be re- utility supply or an on-site electric power source(s). quired for individual unit equipment for standby illumi- 705.2 Definitions. nation. Hybrid System. A system comprised of multiple power (B) Grounding. Where the grounded circuit conductor sources. These power sources could include photovoltaic, connected to the optional standby power source is con- wind, micro-hydro generators, engine-driven generators, nected to a grounding electrode conductor at a location and others, but do not include electric power production remote from the optional standby power source, there shall and distribution network systems. Energy storage systems be a sign at the grounding location that identifies all op- such as batteries, flywheels, or superconducting magnetic tional standby power and normal sources connected at that storage equipment do not constitute a power source for the location. purpose of this definition. Point of Common Coupling.The point at which the power II. Circuit Wiring production and distribution network and the customer inter- face occurs in an interactive system. Typically, this is the 702.9 Wiring Optional Standby Systems. The optional load side of the power network meter. standby system wiring shall be permitted to occupy the same raceways, cables, boxes, and cabinets with other gen- Utility-Interactive Inverter Output Circuit.The conduc- eral wiring. tors between the utility interactive inverter and the service equipment or another electric power production source, such as a utility, for electrical production and distribution M. Grounding network. 702.10 Portable Generator Grounding. 705.3 Other Articles. Interconnected electric power pro- (A) Separately Derived System. Where a portable op- duction sources shall comply with this article and also with tional standby source is used as a separately derived sys- the applicable requirements of the articles in Table 705.3. tem, it shall be grounded to a grounding electrode in accor- Table 705.3 Other Articles dance with 250.30. (B) Nonseparately Derived System.Where a portable op- Equipment/System Article tional standby source is used as a nonseparately derived Generators 445 system, the equipment grounding conductor shall be Solar photovoltaic systems 690 bonded to the system grounding electrode. Fuel cell systems 692 Emergency systems 700 Legally required standby systems 701 IV. Sources of Power Optional standby systems 702 702.11 Outdoor Generator Sets. Where an outdoor 705,4 Equipment Approval. All equipment shall be ap- housed generator set is equipped with a readily accessible proved for the intended use. Utility-interactive inverters for disconnecting means located within sight of the building or interconnection systems shall be listed and identified for structure supplied, an additional disconnecting means shall interconnection service. not be required where ungrounded conductors serve or pass through the building or structure. The disconnecting means 705.10 Directory.A permanent plaque or directory, denot- shall meet the requirements of 225.36. ing all electric power sources on or in the premises, shall be 2008 Edition NATIONAL ELECTRICAL CODE 70--605 705.12 ARTICLE 705—INTERCONNECTED ELECTRIC POWER PRODUCTION SOURCES installed at each service equipment location and at locations Exception: Connection shall be permitted to be made to of all electric power production sources capable of being the load side of ground fault protection, provided that there interconnected. is ground fault protection for equipment from all ground- Exception: Installations with large numbers of power pro- fault current sources. Ground fault protection devices used duction sources shall be permitted to be designated by with supplies connected to the load-side terminals shall be groups. identifted and listed as suitable for backfeeding. 705.12 Point of Connection. The output of an intercon- (4) Marking. Equipment containing overcurrent devices in nected circuits supplying power to a busbar or conductor supplied in 705 electric power source shall be connected as specified from multiple sources shall be marked to indicate the pres- ence(13), {C}, or (D). ence of all sources. (A) Supply Side. An electric power production source (5) Suitable for Baclrfeed. Circuit breakers, if backfed, shall be permitted to be connected to the supply side of the shall be suitable for such operation. service disconnecting means as permitted in 230.82(6). FPN: Circuit breakers that are marked "Line" and "Load" (B) Integrated Electrical Systems. The outputs shall be have been evaluated only in the direction marked. Circuit permitted to be interconnected at a point or points else- breakers without"Line"and"Load"have been evaluated in where on the premises where the system qualifies as an both directions. integrated electrical system and incorporates protective equipment in accordance with all applicable sections of (6) Fastening.Listed. plug-in-type circuit breakers backfed from utility-interactive inverters that are listed and identified Article 685. as interactive shall be permitted to omit the additional fastener (C) Greater Than 100 kW.The outputs shall be permitted normally required by 408.36(D) for such applications. to be interconnected at a point or points elsewhere on the premises where all of the Following conditions are met: (7) Inverter Output Connection. Unless the panelboard is rated not less than the sum of the ampere ratings of all (1) The aggregate of non-utility sources of electricity has a overcurrent devices supplying it, a connection in a panel- capacity in excess of 100 kW, or the service is above board shall be positioned at the opposite (load) end from 1000 volts. the input feeder location or main circuit location. The bus (2) The conditions of maintenance and supervision ensure or conductor rating shall be sized for the loads connected in that qualified persons service and operate the system. accordance with Article 220. In systems with panelboards (3) Safeguards, documented procedures, and protective connected in series,the rating of the first overcurrent device equipment are established and maintained. directly connected to the output of a utility-interactive in- verters)shall be used in the calculations for all busbars and (D) Utility-Interactive Inverters. The output of a utility- conductors. A permanent warning label shall be applied to interactive inverter shall be permitted to be connected to the distribution equipment with the following or equivalent the load side of the service disconnecting means of the wording; other source(s) at any distribution equipment on the pre- mises. Where distribution equipment including switch- WARNING boards and panelboards is fed simultaneously by a primary INVERTER OUTPUT CONNECTION source(s) of electricity and one or more utility-interactive DO NOT RELOCATE THIS inverters, and where this distribution equipment is capable OVERCURRENT DEVICE of supplying multiple branch circuits or feeders or both,the interconnecting provisions for the utility-interactive invert- 705.14 Output Characteristics.The output of a generator er(s) shall comply with (D)(1) through (D)(7). or other electric power production source operating in par- allel with an electrical supply system shall be compatible (I) Dedicated Overcurrent and Disconnect. Each source interconnection shall be made at a dedicated circuit breaker with the voltage, wave shape, and frequency of the system or fusible disconnecting means. to which it is connected. (2) Bus or Conductor Rating. The sum of the ampere FPN: The term compatible does not necessarily mean ratings of overcurrent devices in circuits supplying power matching the primary source wave shape. to a busbar or conductor shall not exceed 120 percent of the 705.16 Interrupting and Short-Circuit Current Rating. rating of the busbar or conductor. Consideration shall be given to the contribution of fault (3) Ground-Fault Protection. The interconnection point currents from all interconnected power sources for the in- shall be on the line side of all ground-fault protection terrupting and short-circuit current ratings of equipment on equipment. interactive systems. 70-606 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 705—INTERCONNECTED ELECTRIC POWER PRODUCTION SOURCES 705.42 705.20 Disconnecting Means,Sources.Means shall be pro- (D) Utility-Interactive Inverters. Utility-interactive in- vided to disconnect all ungrounded conductors of an elec- verters shall be protected in accordance with 705.65. tric power production source(s) from all other conductors. (E) Generators. Generators shall be protected in accor- 705.211 Disconnecting Means, Equipment, Means shall dance with 705.130. be provided to disconnect power production equipment, such as utility interactive inverters or transformers associ- 705.32 Ground-Fault Protection.here ground-fault protec- ated with a power production source, from all ungrounded tion is used, the output of an interactive system shall be con- conductors of all sources of supply. Equipment intended to nected to the supply side of the ground-fault protection. be operated and maintained as an integral part of a power Exception: Connection shall be permitted to be made to production source exceeding 1000 volts shall not be re- the load side of ground fault protection,provided that there quired to have a disconnecting means, is ground fault protection for equipment from all ground- 745.22 Disconnect Device. The disconnecting means for fault current sources. ungrounded conductors shall consist of a manually or 705.40 foss of Primary Source. Upon loss of primary power operable switch(es) or circuit breaker(s) with the source, an electric power production source shall be auto- following features: matically disconnected from all ungrounded conductors of (1) Located where readily accessible the primary source and shall not be reconnected until the (2) Externally operable without exposing the operator to primary source is restored. contact with live parts and, if power operable, of a type Exception: A listed utility-interactive inverter shall be per- that could be opened by hand in the event of a power- mitted to automatically cease exporting power upon loss of supply failure primary source and shall not be required to automatically (3) Plainly indicating whether in the open (of) or closed disconnect all ungrounded conductors g from the primary (on) position source. A listed utility-interactive inverter shall be permit- (4) Having ratings not less than the load to be carried and ted to automatically or manually resume exporting power the fault current to be interrupted. For disconnect to the utility once the primary source is restored. equipment energized from both sides, a marking shall be provided to indicate that all contacts of the discon- FPN No. 1: Risks to personnel and equipment associated with the primary source could occur if an utility interactive nett equipment might be energized. electric power production source can operate as an inten- FPN No. 1 to(4): In parallel generation systems, some equip- tional island. Special detection methods are required to de- ment, including knife blade switches and fuses, is likely to be termine that a primary source supply system outage has energized from both directions. See 240.40. occurred and whether there should be automatic disconnec- tion. When the primary source supply system is restored, FPN No. 2 to (4): Interconnection to an off-premises primary special detection methods can be required to limit exposure source could require a visibly verifiable disconnecting device, of power production sources to out-of-phase reconnection. (5) Simultaneous disconnect of all ungrounded conductors FPN No. 2: Induction-generating equipment on systems of the circuit with significant capacitance can become self-excited upon (6) Capable of being locked in the open (off) position loss of the primary source and experience severe overvolt- age as a result. 705.30 Overcurrent Protection. Conductors shall be pro- tected in accordance with Article 240. Equipment and con- Autility-interactive inverter shall be permitted to oper- ductors connected to more than one electrical source shall ate as a stand-alone system to supply loads that have been have a sufficient number of overcurrent devices located so disconnected from electrical production and distribution as to provide protection from all sources. network sources. (A) Solar Photovoltaic Systems. Solar photovoltaic sys- 705.42 Loss of 3-Phase Primary Source. A 3-phase elec- tems shall be protected in accordance with Article 690. tric power production source shall be automatically discon- nected from all ungrounded conductors of the intercon- (B) Transformers. Overcurrent protection for a trans- nected systems when one of the phases of that source former with a source(s) on each side shall be provided in opens. This requirement shall not be applicable to an elec- accordance with 450.3 by considering first one side of the tric power production source providing power for an emer- transformer, then the other side of the transformer, as the gency or legally required standby system. primary. Exception: A listed utility-interactive inverter shall be per- (C) Fuel Cell Systems. Fuel cell systems shall be pro- mitted to automatically cease exporting power when one of tected in accordance with Article 692, the phases of the source opens and shall not be required to 2008 Edition NATIONAL ELECTRICAL CODF. 70--607 705.50 ARTICLE 705—INTERCONNECTED ELECTRIC POWER PRODUCTION SOURCES automatically disconnect all ungrounded conductors from the (2) The short-circuit currents from all sources do not er- printarti source. A fisted utility-interactive inverter shall be ceed the arnpacity of the conductors. pennitted to automaticalh• or manually resume exporting FPN: possible backfeed of current from any source of sup- power to the utility once all phases of the source are restored. ply,including a supply through an inverter into the inverter output circuit and inverter source circuits,is a consideration 705.50 Grounding. Interconnected electric power produc- in determining whether adequate overcurrent protection tion sources shall be grounded in accordance with Article 250. from all sources is provided for conductors and modules. Exception: For direct-current systems connected through (>B) Power Transformers. Overcurrent protection for a an inverter directly to a grounded service, other methods transformer with a source(s) on each side shall be provided that accomplish equivalent systemt protection and that uti- in accordance with 450.3 by considering first one side of line equipment listed and identified for the use shall be the transformer, then the other side of the transformer, as permitted. the primary. Exception: A power transfonner with a current rating on II. Utility-interactive Inverters the side connected toward the inverter power source not less than the short-circuit output current rating of the in- 705.60 Circuit Sizing and Current. verter shall be permitted without overcurrent protection (A) Calculation of Maximum Circuit Current. The ftoin that source. maximum current for the specific circuit shall be calculated (C) Inverter Source Circuits.Branch-circuit or supplementary- in accordance with 705.60 (A)(1) and (A)(2). type overcurrent devices shall be permitted to provide (1) Inverter Source Circuit Currents. The maximum cur- overcurrent protection in inverter source circuits. The rent shall be the maximum rated input current of the inverter. overcurrent devices shall be accessible but shall not be required to be readily accessible. Standard values of (2) Inverter Output Circuit Current.The maximum cur- supplementary overcurrent devices allowed by this sec- rent shall be the inverter continuous output current rating. tion shall be in one ampere size increments, starting at (B) Ampacity and Overcurrent Device Ratings. Inverter 1 ampere up to and including 15 amperes. Higher stan- system currents shall be considered to be continuous. dard values above 15 amperes for supplementary over- current devices shall be based on the standard sizes pro- (1) Sizing of Conductors and Overcurrent Devices. The vided in 240.6(A). circuit conductors and overcurrent devices shall be sized to carry not less than 125 percent of the maximum currents as (D) Direct-Current Rating. Overcurrent devices, either calculated in 705.60{A). The rating or setting of overcurrent fuses or circuit breakers, used in any de portion of a utility devices shall be permitted in accordance with 240.4{B) and interactive inverter power system shall be listed for use in do circuits and shall have the appropriate voltage, current, (C). and interrupt ratings. Exception: Circuits containing an assembly together with its overcurrent device(s) that is listed for continuous opera- (E) Series Overcurrent Protection. In series-connected pro- tion at 100 percent v,F its racing shall be permitted to he strings of two or more modules, a single overcurrent utilized at 100 percent of its rating. tection device shall be permitted. 705.70 Utility-interactive Inverters Mounted in Not- 7Q5.65 Overcurrent Protection, Readily-Accessible Locations. Utility-interactive inverters (A) Circuits and Equipment. Inverter input circuits, in- shall be permitted to he mounted on roofs or other exterior verter output circuits, and storage battery circuit conductors areas that are not readily accessible. These installations and equipment shall be protected in accordance with the re- shall comply with (1) through (4): quirements of Article 240. Circuits connected to more than (1) A direct-current disconnecting means shall be mounted one electrical source shall have overcurrent devices located so within sight of or in the inverter. as to provide overcurrent protection from all sources. (2) An alternating-current disconnecting means shall he Exception: An overcurrent device shall not be required for mounted within sight of or in the inverter. circuit conductors sized in accordance with 705.60(B) and (3) An additional alternating-current disconnecting means located where one of the following applies: for the inverter shall comply with 705.22. (4) A plaque shall be installed in accordance with 705.10. (I) There are no external sources such as parallel- connected source circuits, batteries, or backfeed front 705.80 Utility-Interactive Power Systems Employing En- inverters. ergy Storage. Utility-interactive power systems employing 7"S NATIONAL,ELECTRICAL,CODE 2008 Edition ARTICLE 708—CRITICAL OPERATIONS POWER SYSTEMS (COPS) 708.2 energy storage shall also be marked with the maximum oper- I. General ating voltage, including any equalization voltage, and the po- 708.1 Scope. The provisions of this article apply to the laxity of the grounded circuit conductor. pP Y installation, operation, monitoring, control, and mainte- 705.82 Hybrid Systems. Hybrid systems shall be permit- nance of the portions of the premises wiring system in- ted to be interconnected with utility-interactive inverters, tended to supply, distribute, and control electricity to des- ignated critical operations areas (DCOA) in the event of 705.95 Ampacity of Neutral Conductor. If a single- disruption to elements of the normal system. phase, 2-wire inverter output is connected to the neutral and Critical operations power systems are those systems so one ungrounded conductor(only) of a 3-wire system or of a classed by municipal, state, federal, or other codes by any 3-phase,4-wire, wye-connected system, the maximum load governmental agency having jurisdiction or by facility en- connected between the neutral and any one ungrounded gineering documentation establishing the necessity for such conductor plus the inverter output rating shall not exceed a system, These systems include but are not limited to the ampacity of the neutral conductor. power systems, HVAC, fire alarm, security, communica- 705.100 Unbalanced Interconnections. tions, and signaling for designated critical operations areas. FPN No. I: Critical operations power systems are gener- (A) Single Phase. Single-phase inverters for hybrid sys- ally installed in vital infrastructure facilities that, if de- tems and ac modules in interactive hybrid systems shall not stroyed or incapacitated, would disrupt national security, be connected to 3-phase power systems unless the intercon- the economy, public health or safety; and where enhanced nected system is designed so that significant unbalanced electrical infrastructure for continuity of operation has been voltages cannot result. deemed necessary by governmental authority. FPN No. 2: For further information on disaster and emer- (B) Three Phase. Three-phase inverters and 3-phase ac gency management see NFPA 1600-2007, Standard on modules in interacfive systems shall have all phases automati- Disaster/Emergence Management and Business Continuity cally de-energized upon loss of, or unbalanced,voltage in one Programs. or more phases unless the interconnected system is designed FPN No.3: For further information regarding performance so that significant unbalanced voltages will not result. of emergency and standby power systems, see NFPA 110- 2005,Standard far Emergency and Standby Power Systems. FPN No.4: For further information regarding performance III. Generators and maintenance of emergency systems in health care fa- 705.130 Overcurrent Protection. Conductors shall be cilities, see NFPA 99-2005, Standard for Health Care protected in accordance with Article 240. Equipment and Facilities. conductors connected to more than one electrical source FPM No. 5: For specification of locations where emer- shall have overcurrent devices located so as to provide pro- gency lighting is considered essential to life safety, see tection from all sources. Generators shall be protected in NFPA 101"-2006, Life Safety Code. accordance with 445.12. FPN No. 6: For further information on regarding physical security, see NFPA 730-2006, Guide for Premises Security. 705.143 Synchronous Generators. Synchronous genera- FPN No.7: Threats to facilities that may require transfer of tors in a parallel system shall be provided with the neces- operation to the critical systems include both naturally oc- sary equipment to establish and maintain a synchronous cuffing hazards and human-caused events. See also A.5.3.2 condition. of NFPA 1600-2007. FPN No. 8: See Annex G for information on Supervisory Control and Data Acquisition. ARTICLE 708 708.2 Definitions. Critical Operations Power Systems Commissioning,The acceptance testing, integrated system (COPS) testing, operational tune-up, and start-up testing is the pro- cess by which baseline test results verify the proper opera- tion and sequence of operation of electrical equipment, in FPN: Rules that are followed by a reference in brackets addition to developing baseline criteria by which future contain text that has been extracted from NFPA 1600-2007, trend analysis can identify equipment deterioration. Standard on Disaster/Emergency Management and Busi- ness Continuity Programs. Only editorial changes were Critical Operations Power Systems (COPS). Power sys- made to the extracted text to make it consistent with this tems for facilities or parts of facilities that require continu- Code. ous operation for the reasons of public safety, emergency management, national security, or business continuity. 2008 Edition NATIONAL ELECTRICAL CODE 70-609 708.3 ARTICLE 708--CRITICAL OPERATIONS POWER SYSTEMS (COPS) Designated Critical Operations Areas (DCOA). Areas 708.6 Testing and Maintenance. within a facility or site designated as requiring critical op- (A) Conduct or Witness Test. The authority having juris- erations power. diction shall conduct or witness a test of the complete sys- Supervisory Control and Data Acquisition (SCADA). tem upon installation and periodically afterward. An electronic system that provides monitoring and controls for the operation of the critical operations power system. (B) Tested Periodically. Systems shall be tested periodi- cally on a schedule acceptable to the authority having ju- This can include the fire alarm system, security system, risdiction to ensure the systems are maintained in proper control of the HVAC, the startlstop/monitoring of the operating condition. power supplies and electrical distribution system,annuncia- tion and communication equipment to emergency person- (C) Maintenance. The authority having jurisdiction shall nel, facility occupants, and remote operators, require a documented preventive maintenance program for critical operations power systems. 708.3 Application of Other Articles. Except as modified FPN: For testing and maintenance procedures, see NFPA by this article, all applicable articles of this Code shall apply. 70B-2006, Recommended Practice for Electrical Equip- ment Maintenance. 708.4 Risk Assessment. Risk assessment for critical op- erations power systems shall be documented and shall be Written Record. A written record shall be kept of such conducted in accordance with 708.4(A) through (C). such tests and maintenance. FPN: Chapter 5 of NFPA 1600-2007,Standard on Disaster/ (E) Testing Under Load. Means for testing all critical Emergency Management and Business Continuity Programs, power systems during maximum anticipated load condi- provides additional guidance concerning risk assessment and tions shall be provided. hazard analysis. FPN: For testing and maintenance procedures of emer- gency power supply systems (EPSSs) that are also appli- (A) Conducting Risk Assessment. In critical operations cable to COPS, see NFPA 110-2005, Standard for Etner- power systems, risk assessment shall be performed to iden- gency and Standby Power Sistems. tify hazards, the likelihood of their occurrence, and the vulnerability of the electrical system to those hazards. 708.8 Commissioning. (B) Identification of Hazards. Hazards to be considered at (A) Commissioning Plan. A commissioning plan shall be a minimum shall include, but shall not be limited to, the developed and documented. following: FPN: For further information on developing a commission- (1) Naturally occurring hazards (geological, meteorologi- ing program see NFPA 70B-2006, Recommended Practice cal, and biological) for Electrical Equipment Maintenance. (2) Human-caused events (accidental and intentional) (B) Component and System Tests.The installation of the [1600:5,3.21 equipment shall undergo component and system tests to en- sure that, when energized, the system will function properly. (C) Developing Mitigation Strategy. Based on the results of the risk assessment, a strategy shall be developed and imple- (C) Baseline Test Results. A set of baseline test results mented to mitigate the hazards that have not been sufficiently shall be documented for comparison with future periodic m maintenance testing to identify equipment deterioration. mitigated by the prescriptive requirements of this Code. (D) Functional Performance Tests. A functional perfor- 708.5 Physical Security. Physical security shall be pro- mance test program shall be established, documented, and vided for critical operations power systems in accordance executed upon complete installation of the critical system with 708.5(A) and (B). in order to establish a baseline reference for future perfor- (A) Risk Assessment. Based on the results of the risk as- mance requirements. sessment, a strategy for providing physical security for FPN: See Annex F for more information on developing critical operations power systems shall be developed, docu- and implementing a functional performance test program. mented, and implemented. II. Circuit Wiring and Equipment (B) Restricted Access. Electrical circuits and equipment 708.10 Feeder and Branch Circuit Wiring. for critical operations power systems shall be accessible to qualified personnel only. (A) Identification. 7"10 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 708—CRITICAL OPERATIONS POWER SYSTEMS (COPS) 708.14 (1) Boxes and Enclosures. All boxes and enclosures (in- (4) Be a cable listed to maintain circuit integrity for not cluding transfer switches,generators,and power panels) for less than 1 hour when installed in accordance with the critical operations power system circuits shall be perma- listing requirement nently marked so they will be readily identified as a com- ponent of the system. (3) Floodplain Protection. Where COPS feeders are in- stalled below the level of the 100-year floodplain, the cir- (2) Receptacle Identification. The cover plates for the cuit conductors shall be listed for use in a wet location and electrical receptacles or the electrical receptacles them- be installed in a wiring method that is permitted for use in selves supplied from the COPS shall have a distinctive wet locations. color or marking so as to be readily identifiable. (D) COPS Brandt Circuit Wiring. (B) Wiring.Wiring of two or more COPS circuits supplied (a) Outside the DCOA. COPS branch circuits installed from the same source shall be permitted in the same race- outside the DCOA shall comply with the physical and fire way, cable, box, or cabinet. Wiring from a COPS source or protection requirements of 708.10(C)(1) through (C)(3). COPS source distribution overcurrent protection to critical (b) Within the DCOA. Any of the wiring methods rec- Ioads shall be kept entirely independent of all other wiring ognized in Chapter 3 of this Code shall be permitted within and equipment. the DCOA. Exception: Where the COPS feeder is installed in transfer 708.11 Branch Circuit and Feeder Distribution equipment enclosures. Equipment. (C) COPS Feeder Wiring Requirements. COPS feeders (A) Branch Circuit Distribution Equipment. COPS shall comply with 708.10(C)(1) through (C)(3). branch circuit distribution equipment shall be located (1) Protection Against Physical Damage. The wiring of within the same DCOA as the branch circuits it supplies. the COPS system shall be protected against physical dam- (B) Feeder Distribution Equipment. Equipment for age. Wiring methods shall be permitted to be installed in COPS feeder circuits (including transfer equipment, trans- accordance with the following: formers, and panelboards) shall comply with (1) and (2). (1) Rigid metal conduit, intermediate metal conduit, or (1) Be located in spaces with a 2-hour fire resistance rating Type MI cable. (2) Be located above the 100-year floodplain. (2) Where encased in not less than 50 mm (2 in.) of con- crete, any of the following wiring methods shall be 708.12 Feeders and Branch Circuits Supplied by permitted: COPS. Feeders and branch circuits supplied by the COPS a. Schedule 40 or Schedule 80 rigid polyvinyl chloride shall supply only equipment specified as required for criti- conduit (Type PVC) cal operations use. b. Reinforced thermosetting resin conduit (Type 708.14 Wiring of HVAC, Fire Alarm, Security, Emer- RTRC) gency Communications, and Signaling Systems.All con- c. Electrical metallic tubing (Type EMT) ductors or cables shall be installed using any of the metal d. Flexible nonmetallic or jacketed metallic raceways ,wing methods permitted by 708.10(C)(1) and in addition e. Jacketed metallic cable assemblies listed for instal- shall comply with 708.14(1) through 708.14(8) as applicable, lation in concrete (3) Where provisions must be made for flexibility at equip- (1) Signal and communication wires shall use shielded ment connection, one or more of the following shall twisted pairs. also be permitted: (2) Shields of signal and communication wires shall be a. Flexible metal fittings continuous. b. Flexible metal conduit with listed fittings (3) Fiber optic cables shall be used for connections be- e. Liquidtight flexible metal conduit with listed fittings tween two or more buildings on the property and under single management. (2) Fire Protection for Feeders. Feeders shall meet one of (4) Listed secondary protectors shall be provided at the the following conditions: terminals of the communication circuits. (1) Be a listed electrical circuit protective system with a (5) Conductors for all control circuits rated above 50V minimum 1-hour fire rating shall be installed with wire rated not less than 600V. (2) Be protected by a fire-rated assembly listed to achieve (6) Communications, fire alarm, and signaling circuits a minimum fire rating of I hour shall use relays with contact ratings that exceed circuit (3) Be embedded in not less than 50 mm(2 in.)of concrete voltage and current ratings in the controlled circuit. 2008 Edition NATIONAL ELECTRICAL CODF 70-611 708.20 ARTICLE 708—CRITICAL OPERATIONS POWER SYSTEMS(COPS) (7) Riser communication cables shall be 2-hour fire- (2) Power for fuel transfer pumps. Where power is resistive cable or a listed 2-hour electrical circuit pro- needed for the operation of the fuel transfer pumps to de- tective system. liver fuel to a generator set day tank, this pump shall be (8) Control, monitoring, and power wiring to HVAC sys- connected to the COPS. tems shall be 2-hour fire-resistive cable or a listed 2-hour electrical circuit protective system. (3) Dual Supplies. Prime movers shall not be solely de- pendent on a public utility gas system for their fuel supply or municipal water supply for their cooling systems. Means III. Power Sources and Connection shall be provided for automatically transferring from one 708.20 Sources of Power. fuel supply to another where dual fuel supplies are used. (A) General Requirements. Current supply shall be such (4) Battery Power and Dampers. Where a storage battery that, in the event of failure of the normal supply to the is used for control or signal power or as the means of DCOA, critical operations power shall be available within starting the prime mover, it shall be suitable for the purpose the time required for the application.The supply system for and shall be equipped with an automatic charging means critical operations power, in addition to the normal services independent of the generator set. Where the battery charger to the building and meeting the general requirements of this is required for the operation of the generator set, it shall be section, shall be one or more of the types of systems de- connected to the COPS. Where power is required for the scribed in 708.20(D) through (H), operation of dampers used to ventilate the generator set, the dampers shall be connected to the COPS. FPN: Assignment of degree of reliability of the recognized critical operations power system depends on the careful (5) Outdoor Generator Sets. Where an outdoor housed evaluation in accordance with the risk assessment. generator set is equipped with a readily accessible discon- (B) Fire Protection. Where located within a building, necting means located within sight of the building or struc- equipment for sources of power as described in 708.20(D) ture supplied, an additional disconnecting means shall not through (H) shall be installed either in spaces fully pro- be required where ungrounded conductors serve or pass tected by approved automatic fire suppression systems through the building or structure. (sprinklers, carbon dioxide systems, and so forth) or in (6) Mean for Connecting Portable or Vehicle-Mounted spaces with a 1-hour fire rating. Generator. Where the COPS is supplied by a single gen- (C) Grounding.All sources of power shall be grounded as erator, a means to connect a portable or vehicle-mounted a separately derived source in accordance with 250.30. generator shall be provided. Exception: Where the equipment containing the main (7) On-Site Fuel Supply. Where internal combustion en- bonding juniper or system handing jumper for the normal gines are used as the prime mover, an on-site fuel supply source and the feeder wiring to the transfer equipment are shall be provided. The on-site fuel supply shall be secured installed in accordance with 708.10(C) and 708.11(B). and protected in accordance with the risk assessment. (D) Surge Protection Devices. Surge protection devices (G) Uninterruptible Power Supplies. Uninterruptible shall be provided at all facility distribution voltage levels. power supplies used as the sole source of power for COPS (E) Storage Battery. An automatic battery charging shall comply with the applicable provisions of 708.20(E) and (F). means shall be provided. Batteries shall be compatible with the charger for that particular installation. For a sealed bat- (H) Fuel Cell System. Installation of a fuel cell system tery, the container shall not be required to be transparent. shall meet the requirements of Parts H through V111 of However, for the lead acid battery that requires water addi- Article 692. tions, transparent or translucent jars shall be furnished. Automotive-type batteries shall not be used. 708.22 Capacity of Power Sources. (F) Generator Set. (A) Capacity and Rating, A COPS shall have capacity (1) Prime Mover-Driven. Generator sets driven by a and rating for all loads to be operated simultaneously for prime mover shall be provided with means for automati- continuous operation with variable load for an unlimited cally starting the prime mover on failure of the normal number of hours, except for required maintenance of the service. A time-delay feature permitting a minimum 15- power source.A portable, temporary,or redundant alternate minute setting shall be provided to avoid retransfer in case power source shall be available for use whenever the COPS of short-time reestablishment of the normal source. power source is out of service for maintenance or repair. 70-612 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 708—CRITICAL OPERATIONS POWER SYSTEMS (COPS) 708.54 (B) Selective Load Pickup, Load Shedding, and Peak 708.30 Branch Circuits Supplied by COPS. Branch cir- Load Sharing.The alternate power source shall be permit- cuits supplied by the COPS shall only supply equipment ted to supply COPS emergency, legally required standby specified as required for critical operations use. and optional loads where the source has adequate capacity or where automatic selective load pickup and load shedding TV. Overcurrent Protection is provided as needed to ensure adequate power to (1) the COPS and emergency circuits, (2) the legally required 70850 Accessibility. The feeder- and branch-circuit over- standby circuits, and (3) the optional standby circuits, in current devices shall be accessible to authorized persons that order of priority. The alternate power source shall be only, permitted to be used for peak Ioad shaving, provided these conditions are met. 708.52 Ground-Fault Protection of Equipment. Peak load-shaving operation shall be permitted for sat- isfying the test requirement of 708.6(B), provided all other (A) Applicability. The requirements of 708.52 shall apply conditions of 708.6 are met. to critical operations (including multiple occupancy build- ings) with critical operation areas. (C) Duration of COPS Operation. The alternate power source shall be capable of operating the COPS for a mini- (B) Feeders. Where ground-fault protection is provided mum of 72 hours at full load of DCOA with asteady-state for operation of the service disconnecting means or feeder voltage within ±10 percent of nominal utilization voltage. disconnecting means as specified by 230.95 or 215.10, an additional step of ground-fault protection shall be provided (D) Ventilation.Adequate ventilation shall be provided for in all next level feeder disconnecting means downstream the alternate power source for continued operation under toward the Ioad. Such protection shall consist of overcur- maximum anticipated ambient temperatures. rent devices and current transformers or other equivalent protective equipment that causes the feeder disconnecting FPN: NFPA 110-2005,Standard fvr E1ttergenc_ti•and Stand- means to open. by Pottier Spstents, and NFPA 111-2005, Standard for Stored Energv Emergency and Stundhv Power Spstems, in- clude additional information on ventilation air for combus- not be installed on electrical systems that are not solidly lion and cooling. grounded wye systems with greater than 150 volts to ground but not exceeding 600 volts phase-to-phase. 708.24 Transfer Equipment. (C) Testing. When equipment ground-fault protection is (A) General. Transfer equipment, including automatic first installed, each level shall be tested to ensure that transfer switches, shall be automatic and identified for ground-fault protection is operational. emergency use. Transfer equipment shall be designed and installed to prevent the inadvertent interconnection of nor- FPN: Testing is intended to verify the ground-fault func- ion is operational. The performance test is not intended to t mat and critical operations sources of supply in any opera- verify selectivity in 708.52(D), as this is often coordinated lion of the transfer equipment. Transfer equipment and similarly to circuit breakers by reviewing tie and current electric power production systems installed to permit op- curves and properly setting the equipment. (Selectivity of eration in parallel with the normal source shall meet the fuses and circuit breakers is not performance tested for requirements of Article 705. overload and short circuit.) (B) Bypass Isolation Switches. Means shall be permitted (D) Selectivity. Ground-fault protection for operation of to bypass and isolate the transfer equipment. Where bypass the service and feeder disconnecting means shall be fully isolation switches are used, inadvertent parallel operation selective such that the feeder device, but not the service shall be avoided. device, shall open on ground faults on the load side of the feeder device.A six-cycle minimum separation between the (C) Automatic Transfer Switches. Where used with service and feeder ground-fault tripping bands shall be pro- sources that are not inherently synchronized, automatic vided. Operating time of the disconnecting devices shall be transfer switches shall comply with (C)(1) and (C)(2). considered in selecting the time spread between these two (1) Automatic transfer switches shall be listed for emer- bands to achieve 100 percent selectivity. gency use. FPN: See 230.95, FPN No. 4, for transfer of alternate (2) Automatic transfer switches shall be electrically oper- source where ground-fault protection is applied. ated and mechanically held. 708.54 Coordination. Critical operations power system(s) (D) Use. Transfer equipment shall supply only COPS overcurrent devices shall be selectively coordinated with all loads. supply side overcurrent protective devices. 2009 Edition NATIONAL ELECTRICAL,CODE 70-613 708.64 ARTICLE 725—CLASS I.CLASS 2,AND CLASS 3 REMOTE-CONTROL,SIGNALING,AND POWER-LIMITED CIRCUITS V. System Performance and Analysis 720,11 Mechanical Execution of Work. Circuits operat- ing at less than 50 volts shall be installed in a neat and 708.64 Emergency Operations Plan. A facility with a workmanlike manner. Cables shall be supported by the COPS shall have documented an emergency operations building structure in such a manner that the cable will not plan. The plan shall consider emergency operations and be damaged by normal building use. response, recovery, and continuity of operations. FPN: NFPA 1600-2007, Standard on Di.sastei/Emergency Management and Business Cantinuim Progrants, Section 5.7, provides guidance for the development and implemen- tation of emergency plans. Class 1, Class 2, and Class 3 Remote-Control, Signaling, and Power-Limited Circuits ARTICLE 720 Circuits and Equipment Operating 1. General at Less Than 50 Volts 725.1 Scope. This article covers remote-control, signaling, and power-limited circuits that are not an integral part of a 720.1 Scope. This article covers installations operating at device or appliance. less than 50 volts, direct current or alternating current. FPN: The circuits described herein are characterized by usage and electrical power limitations that differentiate them from electric light and power circuits,therefore,alter- 720.2 Other Articles. Direct current or alternating-Current native requirements to those of Chapters 1 through 4 are installations operating at less than 50 volts, as covered in given with regard to minimum wire sizes, derating factors, 411.1 through 411.7; Part VI of Article 517; Part 11 Of overcurrent protection, insulation requirements, and wiring Article 551; Parts II and III and 552.60(B) of Article 552; methods and materials. 650.1 through 650.8; 669.1 through 669.9; Parts I and V11I of Article 690;Parts I and III of Article 725;or Parts I and III 725.2 Definitions. of Article 760 shall not be required to comply with this article. Abandoned Class 2, Class 3, and PLTC Cable. Installed Class 2, Class 3, and PLTC cable that is not terminated at 720.3 Hazardous (Classified) Locations. Installations equipment and not identified for future use with a tag, within the scope of this article and installed in hazardous Circuit Integrity (Cl) Cable. Cable(s) used for remote- (classified) locations shall also comply with the appropriate provisions for hazardous (classified) locations in other ap- control, signaling, or power-limited systems that supply plieable articles of this Code. critical circuits to ensure survivability for continued circuit operation for a specified time under fire conditions. 720.4 Conductors. Conductors shall not be smaller than Class 1 Circuit.The portion of the wiring system between 12 AWG copper or equivalent. Conductors for appliance the load side of the overcurrent device or power-limited branch circuits supplying more than one appliance or appli- supply and the connected equipment. ance receptacle shall not be smaller than 10 AWG copper or equivalent. FPN: See 725.41 for voltage and power limitations of Class 1 circuits. 720.5 Lampholders.Standard lampholders that have a rat- Class 2 Circuit.The portion of the wiring system between ing of not less than 660 watts shall be used. the load side of a Class 2 power source and the connected equipment. Due to its power limitations, a Class 2 circuit 720.6 Receptacle Rating. Receptacles shall have a rating considers safety from a fire initiation standpoint and pro- of not less than 15 amperes. vides acceptable protection from electric shock. Class 3 Circuit.The portion of the wiring system between 720.7 Receptacles Required. Receptacles of not less than the load side of a Class 3 power source and the connected 20-ampere rating shall be provided in kitchens, laundries, and equipment. Due to its power limitations, a Class 3 circuit con- other locations where portable appliances are likely to be used. ciders safety from a fire initiation standpoint. Since higher • levels of voltage and current than for Class 2 are permitted, 720.9 Batteries. Installations of storage batteries shall com- additional safeguards are specified to provide protection from ply with 480.1 through 480.4 and 480.8 through 480.10. an electric shock hazard that could be encountered. 70-614 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 725—CLASS 1.CLASS 2,AND CLASS 3 REMOTE-CONTROL,SIGNALING,AND POWER-LIMITED CIRCUITS 725.41 725.3 Other Articles. Circuits and equipment shall com- 725.30 Class 1, Class 2, and Class 3 Circuit Identifiea- ply with the articles or sections listed in 725.3(A) through tion. Class 1, Class 2, and Class 3 circuits shall be identi- (G). Only those sections of Article 300 referenced in this fied at terminal and junction locations in a manner that article shall apply to Class I, Class 2, and Class 3 circuits. prevents unintentional interference with other circuits dur- ing testing and servicing. (A) Number and Size of Conductors in Raceway. Sec- tion 300.17. 725.31 Safety-Control Equipment. (B) Spread of Fire or Products of Combustion. Installa- (A) Remote-Control Circuits. Remote-control circuits for tion of Class 1, Class 2, and Class 3 circuits shall comply safety-control equipment shall be classified as Class 1 if the with 300.21. failure of the equipment to operate introduces a direct fire or life hazard. Room thermostats, water temperature regu- (C) Ducts, Plenums, and Other Air-Handling Spaces. lating devices, and similar controls used in conjunction Class 1, Class 2, and Class 3 circuits installed in ducts, with electrically controlled household heating and air con- plenums, or other space used for environmental air shall ditioning shall not be considered safety-control equipment. comply with 300.22. (B) Physical Protection. Where damage to remote-control Exception: Tvpe CUP or CL3P cables and plenum signal- circuits of safety-control equipment would introduce a haz- ing raceways shall be permitted for Class 2 and Class 3 ard, as covered in 725.31(A), all conductors of such circuits installed in other spaces used for environmental air remote-control circuits shall be installed in rigid metal con- in accordance with 725.154(A). duit, intermediate metal conduit, rigid nonmetallic conduit, electrical metallic tubing, Type MI cable, Type MC cable, (D) Hazardous (Classified) Locations. Articles 500 or be otherwise suitably protected from physical damage. through 516 and Article 517, Part IV, where installed in hazardous (classified) locations. 725.35 Class 1, Class 2, and Class 3 Circuit Require- (E) Cable Trays.Article 392,where installed in cable tray. ments. A remote-control, signaling, or power-limited cir- cuit shall comply with the following parts of this article: (F) Motor Control Circuits. Article 430, Part Vl, where (1) Class I Circuits: Parts I and II tapped from the load side of the motor branch-circuit pro- (2) Class 2 and Class 3 Circuits: Parts I and III tective device(s) as specified in 430.72(A). (G) Instrumentation Tray Cable. See Article 727, II. Class 1 Circuits 725.41 Class 1 Circuit Classifications and Power Source 725.21 Access to Electrical Equipment Behind Panels Requirements. Class 1 circuits shall be classified as either Designed to Allow Access. Access to electrical equipment Class 1 power-Limited circuits where they comply with the shall not be denied by an accumulation of wires and cables power limitations of 725.41(A) or as Class 1 remote- that prevents removal of panels, including suspended ceil- control and signaling circuits where they are used for ing panels. remote-control or signaling purposes and comply with the power limitations of 725.41(B). 725.24 Mechanical Execution of Work. Class 1, Class 2, and Class 3 circuits shall be installed in a neat and work- (A) Class 1 Power-Limited Circuits. These circuits shall manlike manner. Cables and conductors installed exposed be supplied from a source that has a rated output of not on the surface of ceilings and sidewalls shall be supported more than 30 volts and 1000 volt-amperes. by the building structure in such a manner that the cable (1) Class 1 Transformers. Transformers used to supply will not be damaged by normal building use. Such cables power-limited Class 1 circuits shall comply with the appli- shall be supported by straps, staples, hangers, Cable ties, or cable sections within Parts I and II of Article 450. similar fittings designed and installed so as not to damage the cable.The installation shall also comply with 300.4(D). (2) Other Class 1 Power Sources. Power sources other than transformers shall be protected by overcurrent devices 725.25 Abandoned Cables. The accessible portion of rated at not more than 167 percent of the volt-ampere rating abandoned Class 2, Class 3, and PLTC cables shall be re- of the source divided by the rated voltage. The overcurrent moved. Where cables are identified for future use with a devices shall not be interchangeable with overcurrent de- tag,the tag shall be of sufficient durability to withstand the vices of higher ratings. The overcurrent device shall be environment involved. permitted to be an integral part of the power supply. 2008 Edition NATIONAL ELSCrRICAL CODE 70-615 725.43 ARTICLE 725—CLASS 1,CLASS 2,AND CLASS 3 REMOTE-CONTROL,SIGNALING,AND POWER-LIMITED CIRCUITS To comply with the 1000 volt-ampere limitation of protection and shall be permitted to be protected by the 725.41(A), the maximum output (VA mix) of power sources branch-circuit overcurrent protective device(s) where the rat- other than transformers shall be limited to 2500 volt- ing of the protective device(s) is not more than 300 percent of amperes, and the product of the maximum current (Imax) the ampacity of the Class 1 circuit conductor. and maximum voltage (Vm,,,,) shall not exceed 10,000 volt- (D) Primary Side of Transformer.Class 1 circuit conduc- amperes. These ratings shall be determined with any overcurrent-protective device bypassed. tors supplied by the secondary of a single-phase trans- VAm:.x is the maximum volt-ampere output after one former having only a 2-wire (single-voltage) secondary minute of operation regardless of load and with overcurrent shall be permitted to be protected by overcurrent protection protection bypassed, if used. Current-limiting impedance provided on the primary side of the transformer, provided shall not be bypassed when determining VA.,,.,,. [hiti protection is in accordance with 450.3 and does not I. is the maximum output current under any nonca- exceed the value determined by multiplying the secondary pacitive load, including short circuit, and with overcurrent conductor ampacity by the secondary-to-primary trans- protection bypassed, if used. Current-limiting impedance former voltage ratio. Transformer secondary conductors should not be bypassed when determining Imp. Where a other than 2-wire shall not be considered to be protected by current-limiting impedance, listed for the purpose or as part the primary overcurrent protection. of a listed product, is used in combination with a stored (E) Input Side of Electronic Power Source. Class 1 cir- energy source, for example, storage battery, to limit the cuit conductors supplied by the output of a single-phase, output current, Imp, limits apply after 5 seconds. listed electronic power source, other than a transformer, Vm� is the maximum output voltage regardless of load having only a 2-wire(single-voltage) output for connection with rated input applied. to Class i circuits shall be permitted to be protected by overcurrent protection provided on the input side of the (B) Class 1 Remote-Control and Signaling Circuits. electronic power source, provided this protection does not These circuits shall not exceed 600 volts.The power output exceed the value determined by multiplying the Class 1 of the source shall not he required to be limited, circuit conductor ampacity by the output-to-input voltage 725.43 Class 1 Circuit Overcurrent Protection.Overcur- ratio. Electronic power source outputs, other than 2-wire rent protection for conductors 14 AWG and larger shall be (single voltage), shall not be considered to be protected by provided in accordance with the conductor ampacity, with- the primary overcurrent protection, out applying the derating factors of 310.15 to the ampacity 725,46 Class 1 Circuit Wiring Methods. Class 1 circuits calculation. Overcurrent protection shall not exceed 7 am- shall be installed in accordance with Part I of Article 300 peres for 18 AWG conductors and 10 amperes for 16 AWG. and with the wiring methods from the appropriate articles Exception: Where other articles of this Code permit or re- in Chapter 3. quire other overcurrent protection. Exception No. 1: The provisions of 72548 through 725.51 FPN: For example, see 430.72 for motors, 610.53 for shall be permitted to apply in installations of Class 1 cranes and hoists, and 517.74(B) and 660.9 for X-ray circuits. equipment. Exception No. 2: Methods permitted or required by other articles of this Code shall apply to installations of Class 1 725.45 Class 1 Circuit Overcurrent Device Location. circuits. Overcurrent devices shall be located as specified in 725.45(A), (B), (C), (D), or (E). 725.48 Conductors of Different Circuits in the Same Cable, Cable Tray, Enclosure, or Raceway. Class 1 cir- (A) Point of Supply. Overcurrent devices shall be located cuits shall be permitted to be installed with other circuits as at the point where the conductor to be protected receives its specified in 725.48(A) and (B), supply. (A) Two or More Class 1 Circuits.Class 1 circuits shall be (B) Feeder Taps. Class I circuit conductors shall be per- permitted to occupy the same cable, cable tray, enclosure, or mitted to be tapped, without overcurrent protection at the raceway without regard to whether the individual circuits are tap, where the overcurrent device protecting the circuit con- alternating current or direct current, provided all conductors ductor is sized to protect the tap conductor. are insulated for the maximum voltage of any conductor in the (C) Branch-Circuit Taps. Class 1 circuit conductors cable, cable tray, enclosure, or raceway. 14 AWG and larger that are tapped from the load side of the (B) Class 1 Circuits with Power-Supply Circuits. Class 1 overcurrent protective device(s) of a controlled light and circuits shall be permitted to be installed with power-supply power circuit shall require only short-circuit and ground-fault conductors as specified in 725.48(B)(1) through (13)(4). 70-616 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 725—CLASS I,CLASS 2,AND CLASS 3 REMOTE-CONTROL,SIGNALING,AND POWER-LIMITED CIRCUITS 725.121 (1) In a Cable, Enclosure, or Raceway. Class 1 circuits 725.51 Number of Conductors in Cable Trays and and power-supply circuits shall be permitted to occupy the Raceway, and Derating. same cable, enclosure, or raceway only where the equip- ment powered is functionally associated. (A) Class I Circuit Conductors. Where only Class 1 cir- cuit conductors are in a raceway, the number of conductors (2) In Factory-or Field-Assembled Control Centers.Class shall be determined in accordance with 300.17. The derat- circuits and power-supply circuits shall be permitted to be ing factors given in 310.15(B)(2)(a)shall apply only if such installed in factory- or field-assembled control centers. conductors carry continuous loads in excess of 10 percent (3) In a Manhole. Class 1 circuits and power-supply cir- of the ampacity of each conductor. cuits shall be permitted to be installed as underground (B) Power-Supply Conductors and Class 1 Circuit Con- conductors in a manhole in accordance with one of the ductors. Where power-supply conductors and Class l cir- following: cuit conductors are permitted in a raceway in accordance (1) The power-supply or Class 1 circuit conductors are in a with 725.48, the number of conductors shall be determined metal-enclosed cable or Type OF cable. in accordance with 300.17. The derating factors given in (2) The conductors are permanently separated from the 310.I5(B)(2)(a) shalt apply as follows: power-supply conductors by a continuous firmly fixed (1) To all conductors where the Class 1 circuit conductors nonconductor, such as flexible tubing, in addition to the carry continuous loads in excess of 10 percent of the insulation on the wire. ampacity of each conductor and where the total number (3) The conductors are permanently and effectively separated of conductors is more than three from the power supply conductors and securely fastened (2) To the power-supply conductors only, where the Class to racks, insulators, or other approved supports. 1 circuit conductors do not carry continuous loads in (4) In Cable Trays. Installations in cable trays shall com- excess of 10 percent of the ampacity of each conductor and where the number of power-supply conductors is ply with 725.48(B}(4)(1) or (H}(4}(2}. more than three (1) Class I circuit conductors and power-supply conduc- tors not functionally associated with the Class 1 circuit (C) Class 1 Circuit Conductors in Cable Trays. Where conductors shall be separated by a solid fixed barrier of Class 1 circuit conductors are installed in cable trays, they a material compatible with the cable tray. shall comply with the provisions of 392.9 through 392.11. (2) Class 1 circuit conductors and power-Supply conduc- tors not functionally associated with the Class 1 circuit 725.52 Circuits Extending Beyond One Building. Class conductors shall;be permitted to be installed in a cable 1 circuits that extend aerially beyond one building shall tray without barriers where all of the conductor's are also meet the requirements of Article 225. installed with separate multiconductor Type AC, Type MC, Type MI, or Type TC cables and all the conduc- III. Class 2 and Class 3 Circuits tors in the cables are insulated at 600 volts. 725.49 Class 1 Circuit Conductors. 725.121 Power Sources for Class 2 and Class 3 Circuits. (A) Sizes and Use. Conductors of sizes 18 AWG and 16 (A) Power Source. The power source for a Class 2 or a Class 3 circuit shall be as specified in 725.121(A)(1), AWG shall be permitted to be used, provided they supply (A)(2), (A)(3), (A)(4), or (A)(5): loads that do not exceed the ampacities given in 402.5 and are installed in a raceway, an approved enclosure, or a FPN No. 1: Figure 725.121 illustrates the relationships be- listed cable. Conductors larger than 16 AWG shall not sup- tween Class 2 or Class 3 power sources, their supply, and ply loads greater than the ampacities given in 310.15. Flex- the Class 2 or Class 3 circuits. ible cords shall comply with Article 400. FPN No. 2: Table ll(A) and Table I1(B) in Chapter 9 provide the requirements for listed Class 2 and Class 3 (B) Insulation. Insulation on conductors shall be suitable for power sources. 600 volts. Conductors larger than 16 AWG shall comply with (1) A listed Class 2 or Class 3 transformer Article 310. Conductors in sizes 18 AWG and 16 AWG shall (2) A listed Class 2 or Class 3 power supply be Type FFH-2, KF-2, KFF-2, PAR PAFF, PF, PFF, PGF, (3) Other listed equipment marked to identify the Class 2 PGFF, PTF, PTFF, RFH-2, RFHH-2, RFHH-3, SF-2, SFF-2, or Class 3 power source TF, TFF, TFFN, TFN, ZF, or ZFF. Conductors with other types and thicknesses of insulation shall be permitted if listed Exception No. I to (3): Therniocouples shall not require for Class 1 circuit use. listing as a Class 2 power source 2009 Edition NATIONAL ELECTRICAL CODE 70--617 725.124 ARTICLE 725—CLASS I.CLASS 2,AND CLASS 3 REMOTE-CONTROL,SIGNALING.AND POWER-LIMITED CIRCUITS accordance with the appropriate requirements of Chapters 1 Power source— �Wi through pp 725.121(4}(1) I gh 4. Transformers or other devices supplied from I through(A)(4) I electric tight or power circuits shall be protected by an overcurrent device rated not over 20 amperes. Supply I Power source— Class 3 circuit— through r I Exception: The input leads of a transformer or other (0 to 600 I 725.121(A)( 725.133 throw h ac or dc) I (A)(4 725.179 g I power source supplying Class 2 and Class 3 circuits shall be permitted to be smaller than 14 AWG, but not smaller Power source— Class 2 or than 18 AWG if they are not over 12 in. (305 mm)long and 725.121(A)(1) Class 3 circuit-- if they have insulation that complies with 725.49(B). through(A)(4) 725.133 through 725.179 725.127 725.130 1 725.130 Wiring Methods and Materials on Load Side of Part Ill of Article 725 the Class 2 or Class 3 Power Source. Class 2 and Class 3 circuits on the load side of the power source shall be per- Figure. 725.1121 Class 2 and Class 3 Circuits. mitted to be installed using wiring methods and materials in accordance with either 725.134(4) or (13). Exception No. 2 to (3): Limited power circuits of listed equipment where these circuits have energy levels rated at (A) Class 1 Wiring Methods and Materials. Installation or below the limits established in Chapter 9, Table Il(A) shall be in accordance with 725.46. and Table 11(B). Exception No. 1: The derating factors given in 310.15(B) FPN: Examples of other listed equipment are as follows: (2)(a) shall not apply. (1) A circuit card listed for use as a Class 2 or Class 3 Exception No. 2: Class 2 and Class 3 circuits shall be power source where used as part of a listed assembly (2) A current-limiting impedance, listed for the pur- permitted to be reclassified and installed as Class I circuits pose,or part of a listed product,used in conjunction with a if the Class 2 and Class 3 markings required in 725.124 are non-power-limited transformer or a stored energy source, eliminated and the entire circuit is installed using the wir- for example, storage battery, to limit the output current ing methods and materials in accordance with Part If, (3) A thermocouple (4) Limited voltage/current or limited impedance sec- ondary communications circuits of listed industrial control FPN: Class 2 and Class 3 circuits reclassified and installed equipment as Class 1 circuits are no longer Class 2 or Class 3 circuits, (4) Listed information technology (computer) equipment regardless of the continued connection to a Class 2 or Class limited-power circuits. 3 power source. FPN: One way to determine applicable requirements for (g) Class 2 and Class 3 Wiring Methods. Conductors on listing of information technology (computer) equipment is to refer to UL 60950-1-2003, Standard for Safety of lnfor_ the load side of the power source shall be insulated at not nation Technology Equipment. Typically such circuits are less than the requirements of 725.179 and shall be installed used to interconnect information technology equipment for in accordance with 725.133 and 725.154. the purpose of exchanging information (data). (5) A dry cell battery shall be considered an inherently Exception No. 1: As provided for in 620.21 for elevators limited Class 2 power source, provided the voltage is and similar equipment. 30 volts or less and the capacity is equal to or less than Exception No. 2: Other wiring methods and materials in- that available from series connected No. 6 carbon zinc stalled in accordance with the requirements of 725.3 shall cells. be permitted to extend or replace the conductors and cables (B) Interconnection of Power Sources.Class 2 or Class 3 described in 725.179 and permitted by 725.130(B). power sources shall not have the output connections paral- Exception No. 3: Bare Class 2 conductors shall be permit- leled or otherwise interconnected unless listed for such in- ted as part of a listed intrusion protection system where terconnection. installed in accordance with the listing instructions for the system. 725.124 Circuit Marking. The equipment supplying the circuits shall be durably marked where plainly visible to 725.133 Installation of Conductors and Equipment in indicate each circuit that is a Class 2 or Class 3 circuit. Cables, Compartments, Cable Trays, Enclosures, Man- holes, Outlet Boxes, Device Boxes, and Raceways for 725.127 Wiring Methods on Supply Side of the Class 2 Class 2 and Class 3 Circuits. Conductors and equipment or Class 3 Power Source. Conductors and equipment on for Class 2 and Class 3 circuits shall be installed in accor- the supply side of the power source shall be installed in dance with 725.136 through 725.143. 70-618 NATIONAL ELECCRICAL CODE 2008 Edition ARTICLE 725—CLASS 1,CLASS 2,AND CLASS 3 REMOTE-CONTROL.SIGNALING, AND POWER-LIMITED CIRCUITS 725.136 725.136 Separation from Electric Light,Power, Class 1, alarm and medium-power network-powered broadband Non—Power-Limited Fire Alarm Circuit Conductors, communications circuits where they are introduced solely and Medium-Power Network-Powered Broadband to connect the equipment connected to Class 2 and Class 3 Communications Cables. circuits.Where Class 2 and Class 3 circuit conductors must (A) General.Cables and conductors of Class 2 and Class 3 enter an enclosure that is provided with a single opening, circuits shall not be placed in any cable, cable tray, com- they shall be permitted to enter through a single fitting partment, enclosure, manhole, outlet box, device box, race- (such as a tee), provided the conductors are separated from way, or similar fitting with conductors of electric light, the conductors of the other circuits by a continuous and power, Class 1, non—power-limited fire alarm circuits, and firmly fixed nonconductor, such as flexible tubing, medium-power network-powered broadband communica- (F) Manholes. Underground Class 2 and Class 3 circuit tions circuits unless permitted by 725.136(B) through (I). conductors in a manhole shall be permitted to be installed (B) Separated by Barriers. Class 2 and Class 3 circuits with Class 1, non—power-limited fire alarm and medium- shall be permitted to be installed together with the conductors Power network-powered broadband communications cir- of electric light,power,Class 1, non—power-limited fire alarm cuits where one of the following conditions is met: and medium power network-powered broadband communica- (1) The electric light, power, Class 1, non—power-limited tions circuits where they are separated by a barrier. fire alarm and medium-power network-powered broad- band communications circuit conductors are in a metal- (C) Raceways Within Enclosures. In enclosures, Class 2 enclosed cable or Type OF cable. and Class 3 circuits shall be permitted to be installed in a (2) The Class 2 and Class 3 circuit conductors are perma- raceway to separate them from Class 1, non—power-limited nently and effectively separated from the conductors of fire alarm and medium-power network-powered broadband other circuits by a continuous and firmly fixed noncon- communications circuits. ductor, such as flexible tubing, in addition to the insu- (D) Associated Systems Within Enclosures, Class 2 and lation or covering on the wire. Class 3 circuit conductors in compartments, enclosures, de- (3) The Class 2 and Class 3 circuit conductors are perma- vice boxes, outlet boxes, or similar fittings shall be permit- nently and effectively separated from conductors of the ted to be installed with electric light, power, Class 1, non— other circuits and securely fastened to racks, insulators, power-limited fire alarm, and medium-power network- or other approved supports. powered broadband communications circuits where they (G) Cable Trays. Class 2 and Class 3 circuit conductors are introduced solely to connect the equipment connected shall be permitted to be installed in cable trays, where the to Class 2 and Class 3 circuits, and where(1)or(2)applies: conductors of the electric light, Class 1, and non—power- (1) The electric light, power, Class I, non—power-limited limited fire alarm circuits are separated by a solid fixed fire alarm, and medium-power network-powered broad- barrier of a material compatible with the cable tray or band communications circuit conductors are routed to where the Class 2 or Class 3 circuits are installed in Type maintain a minimum of b mm (0.25 in.) separation MC cable. from the conductors and cables of Class 2 and Class 3 circuits. (H) In Hoistways. In hoistways, Class 2 or Class 3 circuit (2) The circuit conductors operate at 150 volts or less to conductors Shall be instaIIed in rigid metal conduit, rigid ground and also comply with one of the following: nonmetallic conduit, intermediate metal conduit, Iiquidtight a. The Class 2 and Class 3 circuits are installed using flexible nonmetallic conduit, or electrical metallic tubing. Type CL3, CL3R, or CL31? or permitted substitute For elevators or similar equipment, these conductors shall cables, provided these Class 3 cable conductors ex- be permitted to be installed as provided in 620.2I. tending beyond the jacket are separated by a minimum of 6 mm (0.25 in.} or by a nonconductive sleeve or (I) Other Applications. For other applications, conductors of Class 2 and Class 3 circuits shall be separated by at least nonconductive barrier from all other conductors. 50 mm (2 in.) from conductors of any electric light, power, b. The Class 2 and Class 3 circuit conductors are in- stalled as a Class 1 circuit in accordance with Class lnon—power-limited fire alarm or medium power network-powered broadband communications circuits un- 725. 1. less one of the following conditions is met: (E) Enclosures with Single Opening. Class 2 and Class 3 (1) Either(a) all of the electric light, power, Class 1, non— circuit conductors entering compartments, enclosures, de- power-limited fire alarm and medium-power network- vice boxes, outlet boxes, or similar fittings shall be permit- powered broadband communications circuit conductors ted to be installed with Class 1, non—power-limited fire or (b) all of the Class 2 and Class 3 circuit conductors 2008 Edition NATIONAL ELECTMICAL CODE. 70-619 725.139 ARTICLE 725—CLASS 1,CLASS 2,AND CLASS 3 REMOTE-CONTROL,SIGNALING,AND POWER-LIMITED CIRCUITS are in a raceway or in metal-sheathed, metal-clad, non— (4) Community antenna television and radio distribution metal]ic-sheathed, or Type OF cables. systems in compliance with Article 820 (2) All of the electric light, power, Class 1 non—power- (5) Low-power, network-powered broadband communica- limited fire alarm, and medium-power network- tions in compliance with Article 830 powered broadband communications circuit conductors are permanently separated from all of the Class 2 and (F) Class 2 or Class 3 Conductors or Cables and Audio Class 3 circuit conductors by a continuous and firmly System Circuits. Audio system circuits described in fixed nonconductor, such as porcelain tubes or flexible 640.9(C), and installed using Class 2 or Class 3 wiring tubing, in addition to the insulation on the conductors. methods in compliance with 725.133 and 725.154, shall not be permitted to be installed in the same cable or raceway 725.139 Installation of Conductors of Different Circuits with Class 2 or Class 3 conductors or cables. in the Same Cable, Enclosure, or Raceway. 725,141 Installation of Circuit Conductors Extending (A) Two or More Class 2 Circuits. Conductors of two or Beyond One Building. Where Class 2 or Class 3 circuit more Class 2 circuits shall be permitted within the same conductors extend beyond one building and are run so as to cable, enclosure, or raceway. he subject to accidental contact with electric light or power conductors operating over 300 volts to ground, or are exposed (B) Two or More Class 3 Circuits, Conductors of two or to lightning on interbuilding circuits on the same premises,the more Class 3 circuits shall be permitted within the same requirements of the following shall also apply: cable, enclosure, or raceway. (1) Sections 800.44, 800.50, 800.53, 800.93, 800.100, 800.170(A), and 800.170(B) for other than coaxial (C) Class 2 Circuits with Class 3 Circuits. Conductors of conductors one or more Class 2 circuits shall be permitted within the (2) Sections 820.44, 820.93, and 820.100 for coaxial same cable, enclosure, or raceway with conductors of Class conductors 3 circuits, provided the insulation of the Class 2 circuit conductors in the cable, enclosure, or raceway is at least 725,143 Support of Conductors. Class 2 Or Class 3 cir- that required for CIass 3 circuits. cuit conductors shall not be strapped, taped, or attached by any means to the exterior of any conduit or other raceway Circuits.Class 2 and Class 3 Circuits with Communications as a means of support.These conductors shall be permitted C to be installed as permitted by 300.11(B)(2), (1) Classified as Communications Circuits. Class 2 and 725.154 Applications of Listed Class 2, Class 3, and Class 3 circuit conductors shall be permitted in the same PLTC Cables. Class 2, Class 3, and PLTC cables shall cable with communications circuits, in which case the comply with any of the requirements described in Class 2 and Class 3 circuits shall be classified as commu- 725.154(A) through (H). nications circuits and shall be installed in accordance with the requirements of Article 800. The cables shall be listed (A) Plenums.Cables installed in ducts, plenums,and other as communications cables. spaces used for environmental air shall be Type CUP or (2) Composite Cables. Cables constructed of individually CL3P. Listed wires and cables installed in compliance with listed Class 2, Class 3, and communications cables under a 300.22 shall be permitted. Listed plenum signaling race- common jacket shall be permitted to be classified as com- ways shall be permitted to be installed in other spaces used munications cables. The fire resistance rating of the com- for environmental air as described in 300.22(0). Only Type CL2P or CUP cable shall be permitted to be installed in posite cable shall be determined by the performance of the composite cable. these raceways. (E) Class 2 or Class 3 Cables with Other Circuit (B) Riser.Cables installed in risers shall be as described in Cables. Jacketed cables of Class 2 or Class 3 circuits shall any of(B)(1), (B)(2), or (11)(3): be permitted in the same enclosure, cable tray, or raceway (1) Cables installed in vertical runs and penetrating more with jacketed cables of any of the following: than one floor, or cables installed in vertical runs in a shaft, (I) Power-limited fire alarm systems in compliance with shall be Type CL2R or CL3R. Floor penetrations requiring Type CUR or CUR shall contain only Article 760 cables suitable for riser or plenum use. Listed riser (2) Nonconductive and conductive optical fiber cables in signaling raceways and listed plenum signaling race- compliance with Article 770 ways shall be permitted to be installed in vertical riser (3) Communications circuits in compliance with Article 800 runs in a shaft from floor to floor. Only Type CL2R, 711-620 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 725—CLASS 1.CLASS 2,AND CLASS 3 REMOTE-CONTROL,SIGNALING, AND POWER-LIMITED CIRCUITS 725.154 CL31Z, CL2P, or CL3P cables shall be permitted to be ported and protected against physical damage using installed in these raceways. mechanical protection such as dedicated struts, angles, (2) Other cables as covered in Table 725.154(G) and other or channels. The cable shall be secured at intervals not listed wiring methods as covered in Chapter 3 shall be exceeding 1.8 m (6 ft), installed in metal raceways, or located in a fireproof (2) Type PLTC cable, without a metallic sheath or armor, shaft having firestops at each floor. that complies with the crush and impact requirements (3) Type CL2, CL3, CL2X, and CL3X cables shall be per- of Type MC cable and identified for such use with the mitted in one- and two-family dwellings. Listed marking PLTC-ER, shall be permitted to be installed general-purpose signaling raceways shall be permitted exposed.The cable shall be continuously supported and for use with Type CL2, CL3, CL2X, and CL3X cables. protected against physical damage using mechanical protection such as dedicated struts, angles, or channels. FPN: See 300.21 for firestop requirements for floor The cable shall be secured at intervals not exceeding penetrations. 1.8 m (6 ft). (C) Cable Trays. Cables installed in cable trays outdoors shall be Type PLTC. Cables installed in cable trays indoors (E) Other Wiring Within Buildings. Cables installed in building locations other than those covered in shall be Types PLTC, CL3P, CL3R, CL3,CL2P,CL2R, and 725.154(A) through (D) shall be as described in any of CL2. (E)(1) through (E)(7). Listed general-purpose signaling raceways, listed riser signaling raceways, and listed plenum signaling raceways (1) General. Type CL2 or CL3 shall be permitted. shall be permitted for use with cable trays. (2) In Raceways or Other Wiring Methods. Type CL2X FPN: See 800.154(D) for cables permitted in cable trays. or CL3X shall be permitted to be installed in a raceway (D) Hazardous (Classified)Locations.Cables installed in or in accordance with other wiring methods covered in Chapter 3. hazardous locations shall be as described in 725.154(D)(1) through (13)(4). (3) Nonconcealed Spaces. Type CL2X and Type CL3X cables shall be permitted to be installed in nonconcealed (1) Type PLTC. Cables installed in hazardous (classified) spaces where the exposed length of cable does not ex- locations shall be Type PLTC.Where the use of Type PLTC seed 3 m ere ft}. cable is permitted by 501.10(B), 502.10(B), and 504.20, the cable shall be installed in cable trays, in raceways, sup- (4) One- and Two-Family Dwellings. Type CL2X cables ported by messenger wire, or otherwise adequately sup- less than 6 mm (0.25 in.) in diameter and Type CL3X ported and mechanically protected by angles, struts, chan- cables less than 6 mm (0.25 in.) in diameter shall be per- nels, or other mechanical means. The cable shall be mitted to be installed in one- and two-family dwellings, permitted to be directly buried where the cable is listed for this use. (5) Multifamily DwelIngs. Type CL2X cables less than 6 mm (0.25 in.) in diameter and Type CL3X cables less (2) Intrinsically Safe Circuits and Nonincendive Field than 6 mm (0.25 in.) in diameter shall be permitted to be Wiring. Wiring for nonincendive circuits as permitted by installed in nonconcealed spaces in multifamily dwellings. 501.10(B)(3), and wiring for intrinsically safe circuits as permitted by 504.20, shall be permitted for circuits derived (6) under Carpets. Type CMUC undercarpet communica- from Class 2 sources. tions wires and cables shall be permitted to be installed under carpet. (3) Thermocouple Circuits. Conductors in Type PLTC cables used for Class 2 thermocouple circuits shall be per- (7) Industrial Establishments. In industrial establish- mitted to be any of the materials used for thermocouple ments where the conditions of maintenance and supervision extension wire. ensure that only qualified persons service the installation, and where the cable is not subject to physical damage,Type (4) In Industrial Establishments. In industrial establish- PLTC cable that complies with the crush and impact re- ments where the conditions of maintenance and supervision quirements of Type MC cable and is identified for such use ensure that only qualified persons service the installation, shall be permitted to be exposed between the cable tray and Type PLTC cable shall be permitted in accordance with the utilization equipment or device.The cable shall be con- either (1) or (2): tinuously supported and protected against physical damage (1) Type PLTC Gable, with a metallic sheath or armor in using mechanical protection such as dedicated struts, accordance with 725.179(E), shall be permitted to be angles, or channels. The cable shall be supported and se- installed exposed. The cable shall be continuously sup- cured at intervals not exceeding 1.8 m (6 ft). 2008 Edition NATIONAL ELECTRICAL CODE 70-621 725.179 ARTICLE 725—CLASS 1,CLASS 2,AND CLASS 3 REMOTE-CONTROL,SIGNALING,AND POWER-LIMITED CIRCUITS (F) Cross-Connect Arrays. Type CL2 or CL3 conductors power-limited systems that supply critical circuits to ensure or cables shall be used for cross-connect arrays. survivability for continued circuit operation for a specified time under fire conditions. (G) Class 2 and Class 3 Cable Substitutions.The substi- tutions for Class 2 and Class 3 cables listed in Table 725.154(G) and illustrated in Figure 725.154((}) shall be IV. Listing Requirements permitted. Where substitute cables are installed, the wiring 725,179 Listing and Marking of Class 2, Class 3, and requirements of Article 725, Parts I and III, shall apply. Type PLTC Cables. Class 2, Class 3, and Type PLTC FPN: For information on Types CMP, CMR, CM, and cables and nonmetallic signaling raceways installed as wir- CMX, see 800.179. ing methods within buildings shall be listed as being resis- Table 725.154(G) Cable Substitutions tant to the spread of fire and other criteria in accordance with 725.179(A) through (K) and shall be marked in accor- Cable Type Permitted Substitutions dance with 725.179(L). CUP CMP (A) Types CL21? and CUP. Types CL2P and CUP ple- CL2P CMP, CL3P num cable shall be listed as being suitable for use in ducts, CL3R CMP, CUP, CMR plenums, and other space for environmental air and shall CL2R CMP CUP, CL2P, CMR, also be listed as having adequate fire-resistant and low PLTC CUR smoke-producing characteristics. CL3 CMP, CUP, CMR, CUR, FPN: One method of defining low smoke-producing cable CMG, CM, PLTC is by establishing an acceptable value of the smoke pro- CL2 CMP, CUP, CL2P, CMR, duced when tested in accordance with NFPA 262-2007, CUR, CL2R, CMG, CM, Standard Method of Test for Flame Travel and Smoke of PLTC, CL3 Wires and Cables for Use in Air-Handling Spaces, to a CL3X CMP, CUP, CMR, CUR, maximum peak optical density of 0.5 and a maximum av- CMG, CM, PLTC, CL3, CMX erage optical density of 0.15. Similarly, one method of de- CL2X CMP, CUP, CL2P, CMR, fining fire-resislant cables is by establishing a maximum CUR, CL2R, CMG, CM, allowable flame travel distance of 1.52 m(5 ft)when tested PLTC, CL3, CL2, CMX, in accordance with the same test. CL3X (B) Types CUR and CUR.Types CL2R and CUR riser cables shall be marked as Type CL2R or CUR, respec- Plenum CMP i CLIP tively, and be listed as suitable for use in a vertical run in a ------------------------- -------- ---- shaft or from floor to floor and shall also be listed as having fire-resistant characteristics capable of preventing the car- Riser CMR CL2R rying of fire f rom floor to floor. FPN: One method of defining fire-resistant characteristics -- capable of preventing the carrying of fire from floor to floor P is that the cables pass the requirements of ANSI/UL 1666- General purpose 2002, Test fur Flame Propagation Height of Electrical and CMG CL3 CL2 Optical-Fiber Cable Installed Vertically in Shafts. CM ------------------- ----------- ---- (C) Types CL2 and CL3. Types CL2 and CL3 cables Dwelling CMX CL3X CL2X shall be marked as Type CL2 or CL3, respectively, and be listed as suitable for general-purpose use, with the excep- Type CM—Communicalions wires and cables tion of risers, ducts, plenums, and other space used for Type CL2 and CL3—Class 2 and Class 3 remote-control,signaling, environmental air, and shall also be listed as being resistant and power-limited cables to the Spread of fire. Type PLTC--Power-limited tray cable FPN: One method of defining resistant to the spread of fire A H Cable A shall be permitted to be used in place of Cable B. is that the cables do not spread fire to the top of the tray in the"UL Flame Exposure.Vertical Tray Flame Test*in UL Figure 725.154(G) Cable Substitution Hierarchy 1685-2000, Standard for Safety for Vertical-Tray Fire- Propagatfon and Shake-Release Test for Electrical and (H) Class 2, Class 3,PLTC Circuit Integrity (CI) Cable Optical-Fiber Cables.The smoke measurements in the test or Electrical Circuit Protective System. Circuit integrity method are not applicable. Another method of defining resistant to the spread of (CI) cable or a listed electrical circuit protective system fire is for the damage(char length)not to exceed 1.5 m(4 ft shall be permitted for use in remote control, signaling, or 11 in.) when performing the CSA"Vertical Flame Test-- 70-622 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 725—CLASS 1,CLASS 2,AND CLASS 3 REMOTE-CONTROL,SIGNALING,AND POWER-LIMITED CIRCUITS 725,179 Cables in Cable Trays," as described in CSA C22.2 No, specified in 725.154(A), (B), (D)(1), and (E), and used for 0.3-M-2001, Test Methods fur Electrical Wirer and Cables. circuit integrity, shall have the additional classification us- (D) Types CL2X and CL3X. Types CL2X and CL3X in g the suffix "-Cl". Cables that are part of a listed electri- limited-use cables shall be marked as Type CL2X or CL3X cal circuit protective system shall be considered to meet the requirements of survivability. respectively, and be listed as being suitable for use in dwellings and for use in raceway and shall also be listed as FPN: One method of defining circuit integrity is by estab- lishing a minimum 2-hour fire resistance rating when tested being resistant to flame spread. in accordance with UL 2196-2002, Standard for Tests of FPN: One method of determining that cable is resistant to Fire Resistive Cables. flame spread is by testing the cable to the VW-1 (vertical wire) flame test in ANSVUL 1581-2001, Reference Stan- (G) Class 2 and Class 3 Cable Voltage Ratings. Class 2 lard for Electrical Wires, Cables and Flexible Cards. cables shall have a voltage rating of not less than 150 volts. Class 3 cables shall have a voltage rating of not less than (E) Type PLTC.Type PLTC nonmetallic-sheathed, power- 300 volts. limited tray cable shall be listed as being suitable for cable trays and shall consist of a factory assembly of two or more (H) Class 3 Single Conductors.Class 3 single conductors insulated conductors under a nonmetallic jacket. The insu- used as other wiring within buildings shall not be smaller lated conductors shall be 22 AWG through 12 AWG. The than 18 AWG and shall be Type CL3. Conductor types conductor material shall be copper (solid or stranded). In- described in 725.49(B) that are also listed as Type CL3 sulation on conductors shall be rated for 300 volts. The shall be permitted. cable core shall be either (1) two or more parallel conduc- tors, (2)one or more group assemblies of twisted or parallel FPN: One method of defining resistant to the spread of fire is that the cables do not spread fire to the top of the tray in conductors, or (3) a combination thereof. A metallic shield the "UL Flame Exposure, Vertical Tray Flame Test"in UL or a metallized foil shield with drain wire(s) shall be per- 1685-2000, Standard far Safety for Vertical-Tray Fire- mitted to be applied either over the cable core, over groups Propagation and Smoke-Release Test for Electrical and of conductors, or both. The cable shall be Iisted as being Optical-Fiber Cables.The smoke measurements in the test resistant to the spread of fire. The outer jacket shall be a method art:not applicable. Another method of defining resistant to the spread of sunlight- and moisture-resistant nonmetallic material. Type fire is for the damage (char length)not to exceed 1.5 m(4 ft PLTC cable used in a wet location shall be listed for use in l l in.) when performing the CSA"Vertical Flame Test— wet locations or have a moisture-impervious metal sheath. Cables in Cable Trays," as described in CSA C22,2 No. 0.3-M-2001.Test Methods far Electrical Wires and Cables. Exception No. 1: Where a smooth metallic sheath, continu- ous corrugated metallic sheath, or interlocking tape armor (I) Plenum Signaling Raceways. Plenum signaling race- is applied over the nonmetallic jacket, an overall nonme- ways shall be listed as having adequate fire-resistant and tallic jacket shall not be required. On metallic-sheathed low smoke-producing characteristics. cable without an overall nonmetallic jacket, the informa tion required in 3 10.11 shall he located on the nonmetallic (J) Riser Signaling Raceways. Riser signaling raceways jacket tinder the sheath. shall be listed as having adequate fire-resistant characteris- tics capable of preventing the carrying of fire from floor to Exception No. 2: Conductors in PLTC cables used for floor. Class 2 thermocouple circuits shall be permitted to be any of the materials used for thermocouple extension wire. FPN: One method of defining fire-resistant characteristics capable of preventing the carrying of fire from floor to Hour FPN: One method of defining resistant to the spread of fire is that the raceways pass the requirements of the Test for is that the cables do not spread fire to the top of the tray in Flame Propagation (Riser) in UL 2024, Standard for Opti- the "U1..Flame Exposure,Vertical Tray Flame Test"in UL cal Fiber Cable Raceway. 1685-2000, Standard for Safety for Vertical-Tray Fire- Propagation and Smoke-Release Test for Electrical and (K) General-Purpose Signaling Raceways. General- optical-Fiber Cables.The smoke measurements in the test purpose signaling raceways shall be listed as being resistant method are not applicable, to the spread of fire. Another method of defining resistant to the spread of fire is for the damage(char length)not to exceed 1.5 m(4 ft FPN: One method of defining resistance to the spread of I1 in.) when performing the CSA"Vertical Flame Test fire is that the raceways pass the requirements of the Cables in Cable Trays," as described in CSA C22.2 No. Vertical-Tray Flame Test (General use) in UL 2024, Stan- 0.3-M-2001, Test Methods for Electrical Wires and Cables. dard for Optical Fiber Cable Raceway. (F) Circuit Integrity (CI) Cable or Electrical Circuit (L) Marking. Cables shall be marked in accordance with Protective System. Cables used for survivability of critical 310,11(A)(2), (A)(3), (A)(4), and (A)(5) and Table circuits shall be listed as circuit integrity (CI)cable. Cables 725.179. Voltage ratings shall not be marked on the cables. 2008 Edition NATIONAL ELECTRICAL CODE 70--623 727.1 ARTICLE 727—INSTRUMENTATION TRAY CABLE:TYPE ITC FPN: Voltage markings on cables may be misinterpreted to plied over the nonmetallic sheath in accordance with suggest that the cables may be suitable for Class I electric 727.6. The cable shall be supported and secured at in- light and power applications. servals not exceeding 1.8 m (6 ft). Exception: Voltage markings shall be permitted where the (5) Cable, without a ,metallic sheath or armor, that com- cable has multiple listings and a voltage marking is re- plies with the crush and impact requirements of Type quired for one or more of the listings. MC cable and is identified for such use with the mark- Table 725.179 Cable Marking ing ITC-ER shall be permitted to be installed exposed. The cable shall be continuously supported and pro- Cable Marking Type tected against physical damage using mechanical pro- tection such as dedicated struts, angles, or channels. CUP Class 3 plenum cable The cable shall be secured at intervals not exceeding CL2P Class 2 plenum cable 1.8 m (b h), CUR Class 3 riser cable CL2R Class 2 riser cable (6) As aerial cable on a messenger. PLTC Power-limited tray cable (7) Direct buried where identified for the use. CL3 Class 3 cable CL2 Class 2 cable (8) Under raised Floors in rooms containing industrial pro- CL3X Class 3 cable, limited use cess control equipment and rack rooms where arranged CL2X Class 2 cable, limited use to prevent damage to the cable. (9) Under raised floors in information technology equip- FPN: Class 2 and Class 3 cable types are listed in descend- ment rooms in accordance with 645.5(D)(5)(c). ing order of fire resistance rating, and Class 3 cables are listed above Class 2 cables because Class 3 cables can 727.5 Uses Not Permitted. Type ITC cable shall not be substitute for Class 2 cables. installed on circuits operating at more than 150 volts or more than 5 amperes. Installation of Type ITC cable with other cables shall be subject to the stated provisions of the specific articles for ARTICLE 727 the other cables. Where the governing articles do not con- Instrumentation Tray Cable: Type ITC tain stated provisions for installation with Type ITC cable, the installation of Type ITC cable with the other cables shall not be permitted. 727.1 Scope. This article covers the use, installation, and Type ITC cable shall not be installed with power, light- construction specifications of instrumentation tray cable for ing, Class 1 circuits that are not power limited, or non-- application to instrumentation and control circuits operating power-limited circuits. at 150 volts or less and 5 amperes or less. Exception No. 1: Where terminated within equipment or 727.2 Definition. junction boxes and separations are maintained by insulat- ing barriers or other►nears. Type ITC Instrumentation Tray Cable. A factory assem- Exception No. 2: Where a nnetallic sheath or armor is ap- bly of two or more insulated conductors, with or without a plied over the nonmetallic sheath of the Type ITC cable. grounding conductor(s), enclosed in a nonmetallic sheath. 727.6 Construction. The insulated conductors of Type 727.3 Other Articles. In addition to the provisions of this ITC cable shall be in sizes 22 AWG through 12 AWG.The article, installation of Type ITC cable shall comply with conductor material shall be copper or thermocouple alloy. other applicable articles of this Code. Insulation on the conductors shall be rated for 300 volts. 727.4 Uses Permitted. Type ITC cable shall be permitted Shielding shall be permitted, to be used as follows in industrial establishments where the The cable shall be listed as being resistant to the spread conditions of maintenance and supervision ensure that only of fire. The outer jacket shall be sunlight and moisture resistant. qualified persons service the installation: Where a smooth metallic sheath, continuous corrugated (1} In cable trays. metallic sheath, or interlocking tape armor is applied over (2) In raceways. the nonmetallic sheath, an overall nonmetallic jacket shall (3) In hazardous locations as permitted in 501.10, 502.10, not be required. 503.10, 504.20, 504.30, 504.80, and 505.15. FPN: One method of defining resistant to the spread af,fire (4) Enclosed in a smooth metallic sheath, continuous cor- is that the cables do not spread fire to the top of the tray in rugated metallic sheath, or interlocking tape armor ap- the"UL Flame Exposure,Vertical Tray Flame Test"in UT, 70-624 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 760—FIRE ALARM SYSTEMS 760.24 1685-2000, Standard for Safery for Vertical-Tray Fire- limited supply and the connected equipment of all circuits Propagation and Smoke-Release Test for Electrical and powered and controlled by the fire alarm system.Fire alarm Optical-Fiber Cables.The smoke measurements in the test circuits are classified as either non—power-limited or method are not applicable. power-limited. p Another method of defining resistant to the spread of p fire is for the damage(char length)not to exceed 1.5 in(4 ft Fire Alarm Circuit Integrity (CI) Cable. Cable used in 11 in.) when performing the CSA"Vertical Flame Test-- Cables in Cable Trays," as described in CSA 022.2 No. fire alarm systems to ensure continued operation of critical 0.3-M-2001,Test Methods for Electrical Wires and Cables. circuits during a specified time under fire conditions. 727.7 Marking. The cable shall be marked in accordance Non—Power-Limited Fire Alarm Circuit(NPLFA).A fire with 310.11(A)(2), (A)(3), (A)(4), and (A)(5). Voltage rat- alarm circuit powered by a source that complies with ings shall not be marked on the cable. 760.41 and 760.43. Power-Limited Fire Alarm Circuit (PLFA). A fire alarm 727.8 Allowable Ampacity.The allowable ampacity of the circuit powered by a source that complies with 760.121. conductors shall be 5 amperes, except for 22 AWG conduc- tors, which shall have an allowable ampacity of 3 amperes. 760.3 Other Articles. Circuits and equipment shall com- ply with 760.3(A) through (G). Only those sections of Ar- 727.9 Overcurrent Protection. Overcurrent protection ticle 300 referenced in this article shall apply to fire alarm shall not exceed 5 amperes for 20 AWG and larger conduc- systems. tors, and 3 amperes for 22 AWG conductors. (A) Spread of Fire or Products of Combustion. Section 727.10 Bends. Bends in Type ITC cables shall be made so 300.21. The accessible portion of abandoned fire alarm as not to damage the cable. cables shall be removed. (B) Ducts, Plenums, and Other Air-Handling Spaces. Section 300.22, where installed in ducts or plenums or ARTICLE 760 other spaces used for environmental air. Fire Alarm Systems Exception: As permitted in 760.530)(1) and (B)(2) and 760.154(A). 1. General (C) Hazardous (Classified) Locations. Articles 500 through 516 and Article 517, Part 1V, where installed in 760.1 Scope. This article covers the installation of wiring hazardous (classified) locations. and equipment of fire alarm systems including all circuits controlled and powered by the fire alarm system. (D) Corrosive, Damp, or Wet Locations. Sections 110.11, 300.6, and 310.9, where installed in corrosive, FPN No. 1: Fire alarm systems include fire detection and damp, or wet locations. alarm notification, guard's tour, sprinkler waterflow, and sprinkler supervisory systems.Circuits controlled and pow- (E) Building Control Circuits. Article 725, where build- ered by the fire alarm system include circuits for the control of building systems safety functions, elevator capture, el- ing control circuits (e.g., elevator capture, fan shutdown) evator shutdown, door release, smoke doors and damper are associated with the fire alarm system. control, fire doors and damper control and fan shutdown, but only where these circuits are powered by and controlled (F) Optical Fiber Cables. Where optical fiber cables are by the fire alarm system. For further information on the utilized for fire alarm circuits, the cables shall be installed installation and monitoring for integrity requirements for in accordance with Article 770, fire alarm systems, refer to the NFPA 72"-2007, National Fire Alarm Code"'. (G) Installation of Conductors with Other,Systems. In- FPN No. 2: Class 1, 2, and 3 circuits are defined in Article stallations shall comply with 300.8. 725. 760.21 Access to Electrical Equipment Behind Panels 760.2 Definitions. Designed to Allow Access. Access to electrical equipment Abandoned Fire Alarm Cable. Installed fire alarm cable shall not be denied by an accumulation of conductors and that is not terminated at equipment other than a connector cables that prevents removal of panels, including suspended and not identified for future use with a tag. ceiling panels. Fire Alarm Circuit. The portion of the wiring system be- 760.24 Mechanical Execution of Work. Fire alarm cir- tween the load side of the overcurrent device or the power- cuits shall be installed in a neat workmanlike manner. 2008 Edition NATIONAL ELECTRICAL CODE 70-625 760.25 ARTICLE 760—FIRE ALARM SYSTEMS Cables and conductors installed exposed on the surface of 760.43 NPLFA Circuit Overcurrent Protection.Overcur ceilings and sidewalls shall be supported by the building rent protection for conductors 14 AWG and larger shall be structure in such a manner that the cable will not be dam- provided in accordance with the conductor ampacity without aged by normal building use. Such cables shall be sup- applying the derating factors of 310.15 to the ampacity calcu- ported by straps, staples, cable ties, hangers, or similar fit- lation. Overcurrent protection shall not exceed 7 amperes for tings designed and installed so as not to damage the cable. 18 AWG conductors and 10 amperes for 16 AWG conductors. The installation shall also comply with 300.4(D). Exception: Where other articles of this Code permit or re- • 760.25 Abandoned Cables. The accessible portion of quire other overcurrent protection. abandoned fire alarm cables shall be removed. Where 760.45 NPLFA Circuit Overcurrent Device Location. cables are identified for future use with a tag,the tag shall Overcurrent devices shall be located at the point where the be of sufficient durability to withstand the environment in- conductor to be protected receives its supply. volved. Exception No. 1: Where the overcurrent device protecting 760.30 Fire Alarm Circuit Identification. Fire alarm cir- the larger conductor also protects the smaller conductor cuits shall be identified at terminal and junction locations in Exception No. 2: Transformer secondary conductors. Non- a manner that helps to prevent unintentional signals on fire power-limited fire alann circuit conductors supplied by the alarm system circuit(s)during testing and servicing of other secondary of a single-phase transformer that has only a systems. 2-wire (single-voltage) secondary shall be permitted to be protected by overcurrent protection provided by the pri- 760.32 Fire Alarm Circuits Extending Beyond One nnary (supply) side of the transformer, provided the protec- Building. Power-limited fire alarm circuits that extend be- tion is in accordance with 450.3 and does not exceed the yond one building and run outdoors either shall meet the value determined by multiplying the secondary conductor installation requirements of Parts II, III, and IV of Article ampacity by the secondary-to-primary transformer voltage 800 or shall meet the installation requirements of Part 1 of ratio. Transformer secondary conductors other than 2-wire Article 300. Non—power-limited fire alarm circuits that ex- shall not be considered to be protected by the primary tend beyond one building and run outdoors shall meet the overcurrent protection. installation requirements of Part I of Article 300 and the applicable sections of Part I of Article 225. Exception No. 3: Electronic power source output conduc- tors. Non—power-limited circuit conductors supplied by the 760.35 Fire Alarm Circuit Requirements. Fire alarm cir- output of a single-phase, listed electronic power source, cuits shall comply with 760.35(A) and (B). other than a transformer, having only a 2-wire (single- voltage) output for connection to non—power-limited cir- (A) Non—Power-Limited Fire Alarm (NPLFA) Circuits. cuits shall be permitted to be protected by overcurrent pro- See Parts I and II. tection provided on the input side of the electronic power source, provided this protection does not exceed the value (B) Power-Limited Fire Alarm (PLFA) Circuits. See determined by multiplying the non—power-limited circuit Parts I and III. conductor ampacity by the output-to-input voltage ratio. Electronic power source outputs, other than 2-wire (single IL Non—Power-Limited Fire Alarm (NPLFA) Circuits voltage), connected to non—power-limited circuits shall not be considered to be protected by overcurrent protection on 760.41 NPLFA Circuit Power Source Requirements. the input of the electronic power source. (A) Power ,Source. The power source of non—power- FPN: A single-phase,listed electronic power supply whose limited fire alarm circuits shall comply with Chapters 1 output supplies a 2-wire (single-voltage) circuit is an ex- ample of a non—power-limited power source that meets the through 4, and the output voltage shall be not more than requirements of 760.41. 600 volts, nominal. 760.46 NPLFA Circuit Wiring. Installation of non- power-limited Branch Circuit. An individual'branch circuit Shall be power-limited fire alarm circuits shall be in accordance required for the supply of the power source. This branch with I10.3(B), 300.7, 300.11, 300.15, 300.17, and other circuit shall not be supplied through ground-fault circuit appropriate articles of Chapter 3. interrupters or arc-fault circuit interrupters. FPN: See 210.8(A)(5), Exception, for receptacles in Exception No. 1: As provided in 760.48 through 760.53. dwelling-unit unfinished basements that supply power for Exception No. 2: Where other articles of this Code require fire alarm systems, other methods. 70-626 NATIONAL aECTRiCAL CODE 2008 Edition ARTICLE 760 FIRE ALARM SYSTEMS 760.53 760.48 Conductors of Different Circuits in Same Cable, alarm circuit conductors are permitted in a raceway in ac- Enclosure, or Raceway. cordance with 760.48, the number of conductors shall be (A) Class I with NPLFA Circuits. Class 1 and non-- determined in accordance with 300.17.The derating factors power-limited fire alarm circuits shall be permitted to oc- given in 310.15(B)(2)(a) shall apply as follows: cupy the same cable, enclosure, or raceway without regard (1) To all conductors where the fire alarm circuit conduc- to whether the individual circuits are alternating current or tors carry continuous loads in excess of 10 percent of direct current, provided ail conductors are insulated for the the ampacity of each conductor and where the total maximum voltage of any conductor in the enclosure or number of conductors is more than three raceway. (2) To the power-supply conductors only, where the fire ($) Fire Alarm with Power-Supply Circuits. Power- alarm circuit conductors do not carry continuous loads supply and fire alarm circuit conductors shall be permitted in excess of 10 percent of the ampacity of each con- in the same cable, enclosure, or raceway only where con- ductor and where the number of power-supply conduc- nected to the same equipment. tors is more than three (C) Cable Trays. Where fire alarm circuit conductors are 760.49 NPLFA Circuit Conductors. installed in cable trays, they shall comply with 392.9 (A) Sizes and Use. Only copper conductors shall be per- through 392.11. mitted to be used for fire alarm systems. Size 18 AWG and 16 AWG conductors shall be permitted to be used,provided 760.53 Multiconductor NPLFA Cables. Multiconductor they supply loads that do not exceed the ampacities given non—power-limited fire alarm cables that meet the require- in Table 402.5 and are installed in a raceway, an approved menu of 760.176 shall be permitted to be used on fire enclosure, or a listed cable. Conductors larger than 16 AWG alarm circuits operating at 150 volts or less and shall be shall not supply loads greater than the ampacities given in installed in accordance with 760.53(A) and (B). 310.15, as applicable. (A) NPLFA Wiring Method. Multiconductor non—power- (B) Insulation. Insulation on conductors shall be suitable limited fire alarm circuit cables shall be installed in accor- for 600 volts. Conductors larger than 16 AWG shall comply dance with 760.53(A)(1), (A)(2), and (A)(3). with Article 310. Conductors 18 AWG and 16 AWG shall (1) Exposed or Fished in Concealed Spaces. In raceway be Type KF-2, KFF-2, PAFF, PTFF. PR PFF, PGF, PG17E or exposed on surface of ceiling and sidewalls or fished in RFH-2, RFHH-2, RFHH-3, SF-2, SFF-2, TF, TFF, TFN, TFFN, ZF, or ZFF. Conductors with other types and thick- concealed spaces. Cable splices or terminations shall be ness of insulation shall be permitted if listed for non— made in listed fittings, boxes, enclosures, fire alarm de- power-limited fire alarm circuit use. vices, or utilization equipment. Where installed exposed, cables shall be adequately supported and installed in such a FPN: For application provisions, see Table 402.3. way that maximum protection against physical damage is afforded by building construction such as baseboards, door (C) Conductor Materials. Conductors shall be solid or frames, ledges, and so forth. Where located within 2.1 m stranded copper. (7 ft) of the floor, cables shall be securely fastened in an E.rception to(B)and(C): Wire Tvpes PAF and PTF shall be approved manner at intervals of not more than 450 mm permitted onl}•for high-temperature applications between (18 in.). 90°C(194°F) and 250°C (482°F). (2) Passing Through a Floor or Wall. In metal raceway 760.51 Number of Conductors in Cable Trays and or rigid nonmetallic conduit where passing through a floor Raceways, and Derating. or wall to a height of 2.1 m (7 ft) above the floor unless adequate protection can be afforded by building construc- (A) NPLFA Circuits and Class 1 Circuits. Where only tion such as detailed in 760.53(A)(1) or unless an equiva- non—power-limited fire alarm circuit and Class I circuit lent solid guard is provided. conductors are in a raceway,the number of conductors shall be determined in accordance with 300.17.The derating fac- (3) In Hoistways. In rigid metal conduit, rigid nonmetallic tors given in 310.15(B)(2)(a) shall apply if such conductors conduit, intermediate metal conduit, liquidtight flexible carry continuous load in excess of 10 percent of the ampac- nonmetallic conduit, or electrical metallic tubing where in- ity of each conductor. stalled in hoistways. (B) Power-Supply Conductors and Fire Alarm Circuit Exception: As provided for in 620.21 for elevators and Conductors. Where power-supply conductors and fire similar equipment. 2008 Edition NATIONAL ELECTRICAL CODE 70--627 760.121 ARTICLE 760—FIRE ALARM SYSTEMS (B) Applications of Listed NPLFA Cables. The use of FPN No. 1: Tables 12(A) and 12(B) in Chapter 9 provide non-power-limited fire alarm circuit cables shall comply the listing requirements for power-limited fire alarm circuit with 760.53(B)(1) through (13)(4). sources. FPN No. 2: See 210.8(A)(5). Exception, for receptacles in (1) Ducts and Plenums. Mul[iconductor non-power- dwelling-unit unfinished basements that supply power for limited fire alarm circuit cables, Types NPLFP, NPLFR, and fire alarm systems. NPLF, shall not be installed exposed in ducts or plenums. (1) A listed PLFA or Class 3 transformer. FPN: See 300.22(B). (2) A listed PLFA or Class 3 power supply. (2) Other Spaces Used for Environmental Air. Cables (3) Listed equipment marked to identify the PLFA power installed in other spaces used for environmental air shall be source. Type NPLFP. FPN: Examples of listed equipment are a lire alarm control panel with integral power source; a circuit card listed for Exception No. 1: Types NPLFR and NPLF cables installed use as a PLFA source, where used as pan of a listed assem- in compliance with 300.22(C). bly;a current-limiting impedance, listed for the purpose or Exception No. 2: Other wiring methods in accordance with part of a listed product, used in conjunction with a non-- 300.22(C) and conductors in compliance with 760.49(C). power-limited transformer or a stored energy source, for example, storage battery, to limit the output current. Exception No. 3: Type NPLFP-CI cable.shall be permitted to be installed to provide a 2-hour circuit integrity rated (B) Branch Circuit. An individual branch circuit Shall be cable. required for the supply of the power source. This branch (3) Riser. Cables installed in vertical runs and penetrating circuit shall not be supplied through ground-fault circuit more than one floor or cables installed in vertical runs in a interrupters or arc-fault circuit interrupters. shaft shall be Type NPLFR. Floor penetrations requiring Type NPLFR shall contain only cables suitable for riser or 760.]24 Circuit Marking. The equipment supplying plenum use. PLFA circuits shall be durably marked where plainly vis- ible to indicate each circuit that is a power-limited fire Exception No. 1: Type NPLF or other cables that are alarm circuit. specified in Chapter 3 and are in compliance with 760.49(C) and encased in metal raceway. FPN: See 760.130(A), Exception No. 3, where a power- Exception No. 2: Type NPLF cables located in a fireproof limited circuit is to be reclassified as a non-power-limited shaft having firestops at each floor. circuit, FPN: See 300.21 for firestop requirements for floor 760.127 Wiring Methods on Supply Side of the PLFA penetrations. Power Source. Conductors and equipment on the supply Exception No. 3: Type NPLF-CI cable shall be permitted side of the power source shall be installed in accordance to be installed to provide a 2-hour circuit integrity rated with the appropriate requirements of Part II and Chapters 1 cable. through 4. Transformers or other devices supplied from (4) Other Wiring Within Buildings. Cables installed in power-supply conductors shall be protected by an overcur- building locations other than the locations covered in rent device rated not over 20 amperes. 760.53(B)(1), (8)(2), and (13)(3) shall be Type NPLF. Exception: The input leads of a transformer or other Exception No. 1: Chapter 3 wiring methods with conduc- power source supplying power-limited fire alarm circuits tors in compliance with 760.49(C). shall be permitted to be smaller than 14 AWG, but not Exception No. 2: Type NPLFP or Type NPLFR cables shall smaller than 18 AWG, if they are not over 300 nun (12 ill.) be permitted. long and if they have insulation that complies with Exception No. 3: Type NPLFR-CI cable shall be permitted 760.49(B). to be installed to provide a 2-hour circuit integrity rated 760.I:30 Wiring Methods and Materials on Load Side of cable. the PLFA Power Source. Fire alarm circuits on the load side of the power source shall be permitted to be installed III. Power-Limited Fire Alarm (PLFA) Circuits using wiring methods and materials in accordance with 760.121 Power Sources for PLFA Circuits. 760.130(A), (B), or a combination of(A) and (B). (A) Power Source. The power source for a power-limited (A) NPLFA Wiring Methods and Materials. Installation fire alarm circuit shall be as specified in 760.121(A)(1), shall be in accordance with 760.46, and conductors shall be (A)(2), or(A)(3). solid or stranded copper. 70-628 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 760—FIRE ALARM SYSTEMS 760.136 Exception No. 1: The derating,factors given in 310.15(B) 760.136 Separation from Electric Light, Power, Class 1, (2)(a) shall not apply. NPLFA, and Medium-Power Network-Powered Broad- Exception No. 2: Conductors and multiconductor cables band Communications Circuit Conductors. described in and installed in accordance with 760.49 and (A) General. Power-limited fire alarm circuit cables and 760.53 shall he permitted. conductors shall not be placed in any cable, cable tray, Exception No. 3: Power-limited circuits shall he permitted compartment, enclosure, manhole, outlet box, device box, to he reclassified and installed as non-power-limited cir- raceway, or similar fitting with conductors of electric light, suits if the poster-limited file alann circuit markings re- power, Class 1, non-power-limited fire alarm circuits, and yuiaed by 760.124 are eliminated and the entire circuit is medium-power network-powered broadband communica- installed using the iviruag methods and materials in actor- lions circuits unless permitted by 760.136(B) through (G). dance with Part 11, Non-Power-Limited Fire Alarm Circuits. (B) Separated by Barriers. Power-limited fire alarm cir- cuit cables shall be permitted to be installed together with FPN: Power-limited circuits reclassified and installed as Class I, non-power-limited fire alarm, and medium-power non-power-limited circuits are no longer power-limited cir- network-powered broadband communications circuits cuits, regardless of the continued connection to a power- where they are separated by a barrier. limited source. (B) PLFA Wiring Methods and Materials.Power-limited (C) Raceways Within Enclosures. In enclosures, power- fire alarm conductors and cables described in 760.179 shall limited fire alarm circuits shall be permitted to be installed be installed as detailed in 760.130(3)(1), (13)(2). or (13)(3) in a raceway within the enclosure to separate them from of this section and 300.7. Devices shall be installed in ac- Class I, non-power-limited fire alarm, and medium-power cardance with 110.3(B), 300.11(A), and 300.15, network-powered broadband communications circuits. (1) Exposed or Fished in Concealed Spaces. In raceway (D) Associated Systems Within Enclosures. Power- or exposed on the surface of ceiling and sidewalls or fished limited fire alarm conductors in compartments, enclosures, in concealed spaces. Cable splices or terminations shall be device boxes, outlet boxes, or similar fittings shall be per- made in listed fittings, boxes, enclosures, fire alarm de- mitted to be installed with electric light, power, Class 1, vices, or utilization equipment. Where installed exposed, non-power-limited tire alarm, and medium power network- cables shall be adequately supported and installed in such a powered broadband communications circuits where they way that maximum protection against physical damage is af- are introduced solely to connect the equipment connected forded by building construction such as baseboards, door to power-limited fire alarm circuits, and comply with either frames,ledges,and so forth.Where located within 2.1 m(7 ft) of the following conditions: of the floor, cables shall be securely fastened in an approved (1) The electric light, power, Class I, non-power-limited manner at intervals of not more than 450 min (I8 in.). fire alarm, and medium-power network-powered broad- band communications circuit conductors are routed to (2) Passing Through a Floor or Wall. In metal raceways maintain a minimum of 6 mm (0.25 in.) separation or rigid nonmetallic conduit where passing through a floor from the conductors and cables of power-limited fire or wall to a height of 2.1 m (7 ft) above the floor, unless alarm circuits. adequate protection can be afforded by building construe- (2) The circuit conductors operate at 150 volts or less to tion such as detailed in 760.130(B)(1) or unless an equiva- ground and also comply with one of the following: lent solid guard is provided. a. The fire alarm power-limited circuits are installed (3) In Hoistways. In rigid metal conduit, rigid nonmetallic using Type FPL, FPLR, FPLP, or permitted substi- conduit, intermediate metal conduit, or electrical metallic tute cables, provided these power-limited cable con- tubing where installed in hoistways. ductors extending beyond the jacket are separated by a minimum of 6 mm (0.25 in.) or by a noncon- Exception: As provided for in 620.21 for elevators and ductive sleeve or nonconductive barrier from all similar equipment• other conductors. b. The power-limited fire alarm circuit conductors are 760.133 Installation of Conductors and Equipment in installed as non-power-limited circuits in accor- Cables, Compartments, Cable Trays, Enclosures, Man- dance with 760.46. holes, Outlet Boxes, Device Boxes, and Raceways for Power-Limited Circuits. Conductors and equipment for (E) Enclosures with Single Opening, Power-limited fire power-limited fire alarm circuits shall be installed in accor- alarm circuit conductors entering compartments, enclo- dance with 760.136 through 760.143, sures,device boxes,outlet boxes, or similar fittings shall be 2008 Edition NATIONAL FUMRICAL CODE 70-629 760.139 ARTICLE 760—FIRE ALARM SYSTEMS permitted to be installed with electric light, power, Class 1, insulation of the Class 2 circuit conductors in the cable, non—power-limited fire alarm, and medium-power network- enclosure, or raceway is at least that required by the power- powered broadband communications circuits where they limited fire alarm circuits. are introduced solely to connect the equipment connected to power-limited fire alarm circuits or to other circuits con- (C) Low-Power Network-Powered Broadband Commu- trolled by the fire alarm system to which the other conduc- nications Cables and PLFA Cables. Low-power network- tors in the enclosure are connected. Where power-limited powered broadband communications circuits shall be per- fire alarm circuit conductors must enter an enclosure that is mitted in the same enclosure, cable tray, or raceway with provided with a single opening, they shall be permitted to PLFA cables. enter through a single fitting (such as a tee}, provided the (D) Audio System Circuits and PLFA Circuits. Audio conductors are separated from the conductors of the other system circuits described in 640,9(C) and installed using circuits by a continuous and Firmly fixed nonconductor, Class 2 or Class 3 wiring methods in compliance with such as flexible tubing. 725.133 and 725.154 shall not be permitted to be installed (F) In Hoistways. In hoistways, power-limited fire alarm in the same cable, cable tray, or raceway with power- circuit conductors shall be installed in rigid metal conduit, limited conductors or cables. rigid nonmetallic conduit, intermediate metal conduit, liq- 760.142 Conductor Size. Conductors of 26 AWG shall be uidtight flexible nonmetallic conduit, or electrical metallic permitted only where spliced with a connector listed as tubing. For elevators or similar equipment, these conduc- suitable for 26 AWG to 24 AWG or larger conductors that tors shall be permitted to be installed as provided in 620.21. are terminated on equipment or where the 26 AWG conduc- (G) Other Applications. For other applications, power- tors are terminated on equipment listed as suitable for limited fire alarm circuit conductors shall be separated by at 26 AWG conductors. Single conductors shall not be smaller least 50 mm (2 in.) from conductors of any electric light, than 18 AWG. power, Class 1, non—power-limited fire alarm, or medium- 760.143 Support of Conductors.Power-limited fire alarm power network-powered broadband communications cir- circuit conductors shall not be strapped, taped, or attached cuits unless one of the following conditions is met: by any means to the exterior of any conduit or other race- (]} Either(a) all of the electric light, power, Class 1, non-- way as a means of support. power-limited fire alarm, and medium-power network- powered broadband communications circuit conductors 760.145 Current-Carrying Continuous Line-Type Fire or (b) all of the power-limited fire alarm circuit con- Detectom ductors are in a raceway or in metal-sheathed, metal- clad, nonmetallic-sheathed, or Type OF cables. (A) Application. Listed continuous line-type fire detec- (2) All of the electric light, power, Class 1, non--power- tors, including insulated copper tubing of pneumatically limited fire alarm, and medium-power network- operated detectors, employed for both detection and carry- powered broadband communications circuit conductors ing signaling currents shall be permitted to be used in are permanently separated from all of the power- power-limited circuits. limited fire alarm circuit conductors by a continuous (B) Installation. Continuous line-type fire detectors shall and firmly fixed nonconductor, such as porcelain tubes be installed in accordance with 760.124 through 760.130 or flexible tubing, in addition to the insulation on the and 760.133. conductors. 760.154 Applications of Listed PLFA Cables. PLFA 760.139 Installation of Conductors of Different PLFA cables shall comply with the requirements described in ei- Circuits,Class 2, Class 3, and Communications Circuits ther 760.154(A), (B), or (C) or where cable substitutions in the Same Cable, Enclosure, Cable Tray, or Raceway, are made as shown in 760.154(D). (A) Two or More PLFA Circuits. Cable and conductors (A) Plenum. Cables installed in ducts, plenums, and other of two or more power-limited fire alarm circuits, commu- spaces used for environmental air shall be Type FPLP. nications circuits, or Class 3 circuits shall be permitted Types FPLP, FPLR,and FPL cables installed in compliance within the same cable, enclosure, cable tray, or raceway. with 300.22 shall be permitted. Type FPLP-Cl cable shall (B) Class 2 Circuits with PLFA Circuits. Conductors of be permitted to be installed to provide a 2-hour circuit integrity rated cable. one or more Class 2 circuits shall be permitted within the same cable, enclosure, cable tray, or raceway with conduc- (B) Riser. Cables installed in risers shall be as described in tors of power-limited fire alarm circuits, provided that the either (1), (2), or (3): 70-6130 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 760—FIRE ALARM SYSTEMS 760.176 (1) Cables installed in vertical runs and penetrating more Multiconductor than one floor, or cables installed in vertical runs in a cables shaft, shall be Type FPLR. Floor penetrations requiring Plenum CMP FPLP Type FPLR shall contain only cables suitable for riser or plenum use. Type FPLR-CI cable shall be permitted ------------------ ---�---to be installed to provide a 2-hour circuit integrity rated Riser CMR FPLR cable. (2) Other cables shall be installed in metal raceways or -- - located in a fireproof shaft having firestops at each General purpose CMG FPL floor. CM (3) Type FPL cable shall be permitted in one- and two- Type CM—Comm unicalions wires and cables family dwellings. Type FPL—Power-limited fire alarm cables FPN: See 300.21 for firestop requirements for floor A t3 Cable A shall be permitted to be used in place of Cable D. penetrations. 26 AWG minimum (C) Other Wiring Within Buildings. Cables installed in Figure 760.154(D) Cable Substitution Hierarchy. building locations other than those covered in 760.I54(A) or (13) shall be as described in either (C)(1), (C)(2), (C)(3), Table 760.154(D) Cable Substitutions or (C)(4). Type FPL-CI cable shall be permitted to be in- stalled as described in either (C)(1), (C)(2), (C)(3), or Permitted (C)(4) to provide a 2-hour circuit integrity rated cable. Cable Type References Substitutions (1) General. Type FPL shall be permitted. FPLP 760,154(A) CMP FPLR 760,154(B) CMP, FPLP, CMR (2) In Raceways. Cables shall be permitted to be installed FPL 760.154(C) CMP, FPLP, CMR, in raceways. FPLR, CMG, CM (3) Nonconcealed Spaces. Cables specified in Chapter 3 (A) NPLFA Conductor Materials. Conductors shall be and meeting the requirements of 760.179(A) and (B) shall 18 AWG or larger solid or stranded copper. be permitted to be installed in nonconcealed spaces where the exposed length of cable does not exceed 3 m (]0 ft). (B) Insulated Conductors. Insulated conductors shall be suitable for 600 volts. Insulated conductors 14 AWG and (4) Portable Fire Alarm System. A portable fire alarm larger shall be one of the types listed in Table 310,13(A) system provided to protect a stage or set when not in use or one that is identified for this use. Insulated conductors shall be permitted to use wiring methods in accordance 18 AWG and 16 AWG shall be in accordance with with 530.12. 760.49. (D) Fire Alarm Cable Substitutions. The substitutions (C) Type NPLFP. Type NPLFP non-power-limited fire for fire alarm cables listed in Table 760.154(D) and Him- alarm cable for use in other space used for environmental trated in Figure 760.154(D) shall be permitted. Where sub- air shall be listed ass being suitable for use in other space stitute cables are installed, the wiring requirements of Ar- used for environmental air as described in 300.22(C) and ticle 760, Parts I and II1, shall apply. shall also be listed as having adequate fire-resistant and low FPN: For information on communications cables (CMP, smoke-producing characteristics, CMR, CMG, CM), see 800.179. FPN: One method of defining low smoke-producing cable is by establishing an acceptable value of the smoke pro- duced when tested in accordance with NFPA 262-2007, IV. Listing Requirements Standard Method of Test for Flame Travel and Smoke of Wires and Cables for Use in Air-Handling Spaces, to a 760.176 Listing and Marking of NPLFA Cables. Non- maximum peak optical density of 0.5 and a maximum av- power-limited fire alarm cables installed as wiring within erage optical density of 0.15. Similarly, one method of de- buildings shall be listed in accordance with 760.176(A) and fining fire-resistant cables is by establishing a maximum (B) and as being resistant to the spread of fire in accordance allowable flame travel distance of 1.52 m(5 ft)when tested in accordance with the same test. with 760.176(C) through (F), and shall be marked in accor- dance with 760.176(G). Cable used in a wet location shall (D) Type NPLFR. Type NPLFR non—power-limited fire be listed for use in wet, locationS or have a moisture- alarm riser cable shall be listed as being suitable for use in impervious metal sheath. a vertical run in a shaft or from floor to floor and shall also 2008 Edition NATIONAL ELECTRICAL CODE 70-631 760.179 ARTICLE 760—FIRE ALARM SYSTEMS be listed as having fire-resistant characteristics capable of Table 760.176(G) NPLFA Cable Markings preventing the carrying of fire from Boor to floor. FPN: One method of defining fire-resistant characteristics Cable capable of preventing the carrying of fire from floor to floor Marking Type Reference is that the cables pass ANSVUL 1666-2002, Test for Flame NPLFP Non-power-limited fire 760.176(C) and Propagation Height of Electrical and Optical-Fiber Cables alarm circuit cable for (G) Installed Vertically in Shafts. use in "other space used (E) Type NPLF.Type NPLF non-power-limited fire alarm for environmental air" NPLFR Non-power-limited fire 760.176(D) and cable shall be listed as being suitable for general-purpose alarm circuit riser cable (G) fire alarm use, with the exception of risers, ducts, plenums, NPLF Non-power-limited fire 760.176(E) and and other space used for environmental air, and shall also alarm circuit cable (G) be listed as being resistant to the spread of fire. Note: Cables identified in 760.176(C), (D), and (E) and meeting the FPN: One method of defining resistant to the spread of fire requirements for circuit integrity shall have the additional classitica- is that the cables do not spread fire to the top of the tray in [ion using the suffix "Cl" (for example, NPLFP-Cl, NPLFR-Cl, and the"UL Flame Exposure,Vertical Tray Flame Test!'in UL NPLF-CI). 1685-2000, Standard for Safety for Vertical-Tray Fire- Propagation and Smoke-Release Test for Electrical and being resistant to the spread of fire and other criteria in Optical-Fiber Cables.The smoke measurements in the test accordance with 760.179(A) through (H) and shall be method are not applicable. marked in accordance with 760.179(I). Insulated continu- Another method of defining resistant to the spread of fire is for the damage(char length)not to exceed 1.5 m(4 ft ous line-type fire detectors shall be listed in accordance I l in.) when performing the CSA "Vertical Flange Test— with 760.179(1). Cable used in a wet location shall be listed Cables in Cable Trays," as described in CSA C22.2 No. for use in wet Iocations or have a moisture-impervious 0.3-M-2001, Test Methods for Electrical Wires and Cables. metal Sheath (F) Fire Alarm Circuit Integrity (CI) Cable or Electri- (A) Conductor Materials. Conductors shall be solid or cal Circuit Protective System. Cables used for survivabil- stranded copper. ity of critical circuits shall be listed as circuit integrity (CI) cable. Cables specified in 760.176(C), (D), and (E), and (B) Conductor Size.The size of conductors in a multicon- used for circuit integrity shall have the additional classifi- ductor cable shall not be smaller than 26 AWG. Single cation using the suffix "-Cl." Cables that are part of a listed conductors shall not be smaller than 18 AWG. electrical circuit protective system shall be considered to meet the requirements of survivability. (C) Ratings. The cable shall have a voltage rating of not less than 300 volts. FPN No. I: Fire alarm circuit integrity(CI)cable and elec- trical circuit protective systems may be used for fire alarm (D) Type FPLP. Type FPLP power-limited fire alarm ple- circuits to comply with the survivability requirements of num cable shall be listed as being suitable for use in ducts, NFPA 72'-2007, National Fire Alarm Code", 6.9.4.3 and plenums, and other space used for environmental air and 6.9.4.6, that the circuit maintain its electrical function dur- ing fire conditions for a defined period of time. shall also be listed as having adequate fire-resistant and low FPN No. 2: One method of defining circuit integrity (CI) smoke-producing characteristics. cable is by establishing a minimum 2-hour fire resistance FPN: One method of defining low smoke-producing cable rating for the cable when tested in accordance with UL is by establishing an acceptable value of the smoke pro- 2196-1995, Standard for Tests of Fire Resistive Cables. duced when tested in accordance with NFPA 262-2007, Standard Method of Test for Flame Travel and Smoke of (G) NPLFA Cable Markings. Multiconductor non– Wires and Cables for Use in Air-Handling Spaces, to a power-limited fire alarm cables shall be marked in accor- maximum peak optical density of 0.5 and a maximum av- dance with Table 760.176(G). Non–power-limited fire erage optical density of 0.15. Similarly, one method of de- fining fire-resistant cables is by establishing a maximum alarm circuit cables shall be permitted to be marked with a allowable flame travel distance of 1.52 m(5 ft)when tested maximum usage voltage rating of 150 volts. Cables that are in accordance with the same test. listed for circuit integrity shall be identified with the suffix "CI" as defined in 760.176(F). (E) Type FPLR.Type FPLR power-limited fire alarm riser FPN: Cable types are listed in descending order of fire cable shall be listed as being suitable for use in a vertical resistance rating, run in a shaft or from Boor to Boor and shall also be listed as having fire-resistant characteristics capable of preventing 760.179 Listing and Marking of PLFA Cables and In- the carrying of fire from floor to floor. sulated Continuous Line-Type Fire Detectors. Type FPL FPN: One method of defining fire-resistant characteristics cables installed as wiring within buildings shall be listed as capable of preventing the carrying of fire from floor to floor 70-632 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 771)—OPTICAL FIBER CABLES AND RACEWAYS 770,2 is that the cables pass the requirements of ANSIIUL 1666- Table 760.179(1) Cable Markings 2002,Standard Test for Flame Propagation Height of Elec- trical and Optical-Fiber Cable Installed Vertically in Cable Marking Typ e Shafts. {F} Type FPL. Type FPL power-limited fire alarm cable FPLP Power-limited fire alarm plenum cable shall be listed as being suitable for general-purpose fire FPLR Power-limited fire alarm riser alarm use, with the exception of risers, ducts, plenums, and cable other spaces used for environmental air, and shall also be FPL Power-limited fire alarm cable listed as being resistant to the spread of fire. Note: Cables identified in 760.179(D), (E), and (F) as meeting the re- FPN: One method of defining resistant to the spread of fire quirements for circuit integrity shall have the additional classification is that the cables do not spread fire to the top of the tray in using the suffix"CF(for example, FPLP-CI,FPLR-CI,and FPL-CI). the "UL Flame Exposure,Vertical Tray Flame Test" in UL 1685-2000, Standard for Safety for Vertical-Tray Fire- FPN: Cable types are listed in descending order of fire- Propagation and Smoke-Release Test for Electrical and resistance rating. Optical-Fiber Cables.The smoke measurements in the test method are not applicable. (J) Insulated Continuous Line-Type Fire Detectors. In- Another method of defining resistant to the spread of sulated continuous line-type lire detectors shall be rated in fire is for the damage(char length)not to exceed 1.5 m(4 ft accordance with 760.179(C), listed as being resistant to the I in.) when performing the CSA "Vertical Flame Test— spread of fire in accordance with 760.I79(D) through (F), Cables in Cable Trays," as described in CSA C22.2 No. 0.3-M-2001, Test Methods for Electrical Wires and Cables. marked in accordance with 760.I79(I), and the jacket com- pound shall have a high degree of abrasion resistance. (G) Fire Alarm Circuit Integrity (CI) Cable or Electri- cal Circuit Protective System. Cables used for survivabil- ity of critical circuits shall be listed as circuit integrity (CI) cable. Cables specified in 760.179(D), (E), (F), and (H) and used for circuit integrity shall have the additional classifi- ARTICLE 770 cation using the suffix "-CI." Cables that are part of a listed Optical Fiber Cables and Raceways electrical circuit protective system shall be considered to meet the requirements of survivability. 1. General FPN No. l: Fire alarm circuit integrity(CI)cable and elec- trical circuit protective systems may be used for fire alarm 770.1 Scope. The provisions of this article apply to the circuits to comply with the survivability requirements of installation of optical fiber cables and raceways.This article NFPA 72-2007, National Fire Alarm Code, 6.9.4.3 and does not cover the construction of optical fiber cables and 6.9.4.6, that the circuit maintain its electrical function dur- raceways. ing fire conditions for a defined period of time, FPN No. 2: One method of defining circuit integrity (CI) 770.2 Definitions. See Article 100. For purposes of this cable is by establishing a minimum 2-hour fire resistance article, the following additional definitions apply. rating for the cable when tested in accordance with UL Pp y' 2196-1995. Standard for Tests of Fire Resistive Cables. Abandoned Optical Fiber Cable. Installed optical fiber (H) Coaxial Cables. Coaxial cables shall be permitted to cable that is not terminated at equipment other than a con- use 30 percent conductivity copper-covered steel center Hector and not identified for future use with a tag. conductor wire and shall be listed as Type FPLP, FPLR, or FPN: See Article 100 for a definition of Equipment. FPL cable. Cable Sheath. A covering over the optical fiber assembly (I) Cable Marking. The cable shall be marked in accor- that includes one or more jackets and may include one or dance with Table 760.179(I).The voltage rating shall not be more metallic members or strength members. marked on the cable. Cables that are listed for circuit integ- Composite Optical Fiber Cable.These cables contain op- rity shall be identified with the suffix Cl as defined in tical fibers and current-carrying electrical conductors. 760.179(G). FPN: Voltage ratings on cables may be misinterpreted to Conductive Optical Fiber Cable. These optical fiber suggest that the cables may be suitable for Class 1,electric cables contain non-current-carrying conductive members light, and power applications. such as metallic strength members, metallic vapor barriers, Exception: Voltage markings shall be permitted where the and metallic armor or Sheath. cable has multiple listings and voltage marking is required Exposed (to Accidental Contact). A conductive optical for one or more of the listings. fiber cable in such a position that, in case of failure of 2008 Edition NATIONAL.ELECTRICAL CODE 70-633 770.3 ARTICLE 770—OPTICAL FIBER CABLES AND RACEWAYS supports or insulation, contact between the cable's non- cables that prevents removal of panels,including suspended current-carrying conductive members and an electrical cir- ceiling panels. cuit may result. 770.24 Mechanical Execution of Work. Optical fiber FPN: See Article 100 for two other definitions of E>pnsed' cables shall be installed in a neat and workmanlike manner. Nonconductive Optical Fiber Cable. These optical fiber Cables installed exposed on the surface of ceilings and cables contain no metallic members and no other electri- sidewalls shall be supported by the building structure in cally conductive materials. such a manner that the cable will not be damaged by nor- mal building use. Such cables shall be secured by hardware Optical Fiber Cable. A factory assembly of one or more including straps, staples, cable ties, hangers, or similar fit- optical fibers having an overall covering, tings designed and installed so as not to damage the cable. Optical Fiber Raceway.A raceway for enclosing and rout- The installation shall also conform with 300.4(D) and ing optical fiber cables. 300.11. FPN: See Article 100 for a definition of Raceway. FPN: Accepted industry practices are described in ANSI/NECAIBICSI 569-2001, Standard for Installing Point of Entrance. The point within a building at which Commercial Building Telecommunications Cabling, the cable emerges from an external wall, from a concrete ANSYNECAIFOA 301-2004, Standard fvr Installing and Testing Fiber Optic Cables, and other ANSI-approved in- Hoorslab, or from a rigid metal conduit(Type RMC) or an slallation standards. intermediate metal conduit (Type IMQ connected by a grounding conductor to an electrode in accordance with 770.25 Abandoned Cables. The accessible portion of 770.100(3), abandoned optical fiber cables shall be removed. Where cables are identified for future use with a tag, the tag shall '770.3 Other Articles. Circuits and equipment shall con- be of sufficient durability to withstand the environment in- ply with 770.3{A) and (13}. Only those sections of Chapter volved. 2 and Article 300 referenced in this article shall apply to optical fiber cables and raceways. 770.26 Spread of Fire or Products of Combustion. In- (A) Composite Cables. Composite optical fiber cables stalIations of optical fiber cables and raceways in hollow shall be classified as electrical cables in accordance with spaces,vertical shafts, and ventilation or air-handling ducts the type of electrical conductors.They shall be constructed, shall be made so that the possible spread of fire or products Listed, and marked in accordance with the appropriate ar- of combustion will not be substantially increased.Openings ticle for each type of electrical cable. around penetrations of optical fiber cables and raceways through fire-resistant-rated walls,partitions, floors, or ceil- (B) Ducts, Plenums, and Other Air-Handling Spaces. ings Shaul be firestopped using approved methods to main- The requirements of 300.22 for electric wiring shall also tain the fire resistance rating. apply to installations of optical fiber cables and raceways FPN: Directories of electrical construction materials pub- where they are installed in ducts or plenums or other space lished by qualified testing laboratories contain many listing used for environmental air. installation restrictions necessary to maintain the fire- resistive rating of assemblies where penetrations or open- Exception: As pennitterl in 770.154(A). ing are made. Building codes also contain restrictions on membrane penetrations on apposite sides of a fire- 770.6 Optical Fiber Cables. Optical fiber cables transmit resistance-rated wall assembly.An example is the 600-mm light for control,signaling, and communications through an (24-in.)minimum horizontal separation that usually applies between boxes installed on opposite sides of the wall.As- optical fiber. sistartee in complying with 770.26 can be tbund in building codes,fire resistance directories,and:Product listings. 770.12 Innerduct for Optical Fiber Cables. Listed ple- num optical fiber raceway,listed riser optical fiber raceway, or listed general-purpose optical fiber raceway selected in H. Cables Outside and Entering Buildings. accordance with the provisions of 770.154 shall be permit- 770.48 Unlisted Cables and Raceways Entering Build- ted to be installed as innerduct in any type of listed raceway ings. permitted in Chapter 3. • (A) Conductive and Nonconductive Cables. Unlisted 770.21 Access to Electrical Equipment Behind Panels conductive and nonconductive outside plant optical fiber Designed to Allow Access. Access to electrical equipment cables shall be permitted to be installed in locations as shall not be denied by an accumulation of optical fiber described in 770.154(C), where the length of the cable 70-634 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 770—OPTICAL FIBER CABLES AND RACEWAYS 770.100 within the building, measured from its point of entrance, (3) Size. The grounding conductor shall not be smaller does not exceed 15 m (50 ft) and the cable enters the than 14 AWG. It shall have a current-carrying capacity building from the outside and is terminated in an enclosure, approximately equal to or greater than that of the metallic FPN No. 1: Splice cases or terminal boxes, both metallic member(s). The grounding conductor shall not be required and plastic types,typically are used as enclosures for splie- to exceed 6 AWG. ing or terminating optical fiber cables. (4) Run in Straight Line. The grounding conductor shall FPN No. 2: See 770.2 for the definition of Point of be run to the grounding electrode in as straight a line as Entrance. practicable. (B) Nonconductive Cables. Unlisted nonconductive opti- (5) Physical Damage. Where necessary, the grounding cal fiber outside plant optical fiber cables shall be permitted conductor shall be guarded from physical damage. Where to enter the building from the outside and run in raceway the grounding conductor is run in a metal raceway, both systems installed in compliance with any of the following ends of the raceway shall be bonded to the grounding con- articles in Chapter 3:Article 342,Intermediate Metal Conduit: ductor or the same terminal or electrode to which the Type 1MC; Article 344, Rigid Metal Conduit: Type RMC, grounding conductor is connected. Article 352, Rigid Polyvinyl Chloride Conduit: Type PVC; and Article 358,Electrical Metallic Tubing: Type EMT. (B) Electrode. The grounding conductor shall be con- nected in accordance with 770.100(B)(1), (13)(2),or(B)(3). III. Protection (1) In Buildings or Structures with an Intersystem 770.93 Grounding or Interruption of Non-Current- Bonding Termination. If the building or structure served Carrying Metallic Members of Optical Fiber Gables.. has an intersystem bonding termination, the grounding Optical fiber cables entering the building or terminating on the conductor shall be connected to the intersystem bonding outside of the building shall comply with 770.93(A) or(B). termination. (A) Entering Buildings. In installations where an optical (2) In Buildings or Structures with Grounding Means. fiber cable is exposed to contact with electric light or power If the building or structure served has no intersystem bond- conductors and the cable enters the building, the non- ing termination, the grounding conductor shall be con- current-carrying metallic members shall be either grounded nected to the neatest accessible location on the following: as specified in 770.100,or interrupted by an insulating joint (1) The building or structure grounding electrode system or equivalent device.The grounding or interruption shall be as covered in 250.50 as close as practicable to the point of entrance. (2) The grounded interior metal water piping system, (B) Terminating On the Outside of Buildings. In instal- within 1.5 m (5 ft) from its point of entrance to the lations where an optical fiber cable is exposed to contact building, as covered in 250.52 with electric light or power conductors and the cable is (3) The power service accessible means external to enclo- terminated on the outside of the building, the non-current- sures as covered in 250.94 carrying metallic members shall be either grounded as (4) The metallic power service raceway specified in 770.100, or interrupted by an insulating joint or (5) The service equipment enclosure equivalent device.The grounding or interruption shall be as (6) The grounding electrode conductor or the grounding close as practicable to the point of termination of the cable. electrode conductor metal enclosure (7) The grounding conductor or the grounding electrode of IV. Grounding Methods a building or structure disconnecting means that is 770.100 Entrance Cable Grounding. Where grounded, grounded to an electrode as covered in 250.32 the non-current-carrying metallic members of optical fiber (3) In Buildings or Structures Without intersystem cables entering buildings shall be grounded as specified in Bonding Termination or Grounding Means.If the build- 770.100(A) through (D). ing or structure served has no intersystem bonding termi- (A) Grounding Conductor. nation or grounding means, as described in 770.100(B)(2), the grounding conductor shall be connected to either of the (1) Insulation.The grounding conductor shall be insulated following: and shall be listed. (l) To any one of the individual electrodes described in (2) Material. The grounding conductor shall be copper or 250.52(A)(1), (A)(2), (A)(3), or(A)(4). other corrosion-resistant conductive material, stranded or (2) If the building or structure served has no grounding solid. means, as described in 770.100(B)(2) or (B)(3)(1), to 2009 Edition NATIONAL ELEC"CRICAL CODE 70-635 770.101 ARTICLE 770—OPTICAL FIBER CABLES AND RACEWAYS an effectively grounded metal structure or to a ground V. Installation Methods Within Buildings rod or pipe not less than 1.5 m (5 ft) in length and 12.7 mm ( in.) in diameter, driven, where practicable, 770.110 Raceways for Optical Fiber Cables. Where op- into permanently damp earth and separated from light- tical fiber cables are installed in a raceway, the raceway ning conductors as covered in 800.53 and at least 1.$m shall be either of a type permitted in Chapter 3 and installed (6 ft) from electrodes of other systems. Steam or hot in accordance with Chapter 3 or listed plenum optical fiber water pipes or air terminal conductors (lightning-rod raceway,listed riser optical fiber raceway, or listed general- Conductors) shall not be employed as electrodes for purpose optical fiber raceway selected in accordance with protectors. the provisions of 770.154, and installed in accordance with 362.24 through 362.56, where the requirements applicable (C) Electrode Connection. Connections to grounding to electrical nonmetallic tubing apply. Where optical fiber electrodes shall comply with 250.70. cables are installed in raceway without current-carrying conductors,the raceway fill tables of Chapter 3 and Chapter (D) Bonding of Electrodes.A bonding jumper not smaller 9 shall not apply.Where nonconductive optical fiber cables than 6 AWG copper or equivalent shall be connected be- are installed with electric conductors in a raceway,the race- tween the grounding electrode and power grounding elec- way fill tables of Chapter 3 and Chapter 9 shall apply. trode system at the building or structure served where sepa- rate electrodes are used. 770.113 Installation of Optical Fiber Cables. Optical fi- Exception: At mobile homes as covered in 770.106. ber cables installed in buildings shall be listed. FPN No. 1: See 280.60 for use of air te rminals (lightning Exception: Optical fiber cables that comply with 770.48 rods). shall not be required to be lister!. FPN No. 2: Bonding together of all separate electrodes 770.133 Installation of Optical Fibers and Electrical limits potential differences between them and between their associated wiring systems. Conductors. (A) With Conductors for Electric Light,Power, Class 1, 770.101 Grounding. Non—current-carrying conductive Non—Power-Limited Fire Alarm, or Medium Power members of optical fiber cables shall be grounded accord- Network-Powered Broadband Communications Cir- ing to the grounding methods specified by 770.100. cuits. When optical fibers are within the same composite cable for electric light, power, Class 1, non—power-limited 770.106 Grounding of Entrance Cables at Mobile fire alarm, or medium-power network-powered broadband Homes. Where grounded as required by 770.100 at a mo- communications circuits operating at 600 volts or less, they bile home, the non—current-carrying metallic members of shall be permitted to be installed only where the functions of optical fiber cables entering buildings shall be grounded as the optical fibers and the electrical conductors are associated. specified in 770.106(A) and (B). Nonconductive optical fiber cables shall be permitted to occupy the same cable tray or raceway with conductors for (A) Grounding. Where there is no mobile home service electric light,power, Class 1, non--power-limited fire alarm, equipment located within 9.0 m (30 ft) from the exterior Type ITC, or medium-power network-powered broadband wall of the mobile home it serves, or there is no mobile communications circuits, operating at 600 volts or less. home disconnecting means grounded in accordance with Conductive optical fiber cables shall not be permitted to 250.32 and located within 9.0 m (30 ft) from the exterior occupy the same cable tray or raceway with conductors for wall of the mobile home it serves, the ground for non— electric light, power,Class 1, non—power-limited fire alarm, current-carrying metallic members of optical fiber cables Type ITC, or medium-power network-powered broadband entering buildings Shall be in accordance with communications circuits. 770.100(B)(3). Optical fibers in composite optical fiber cables contain- ing only current-carrying conductors for electric light, (B) Bonding.The primary protector grounding terminal or power, Class I circuits rated 600 volts or less shall be grounding electrode shall be bonded to the metal frame or permitted to occupy the same cabinet, cable tray, outlet available grounding terminal of the mobile home with a box, panel, raceway, or other termination enclosure with copper grounding conductor not smaller than 12 AWG un- conductors for electric light, power, or Class 1 circuits op- der either of the following conditions: erating at 600 volts or less. (1) Where there is no mobile home service equipment or Nonconductive optical fiber cables shall not be permitted disconnecting means as in 770.106(A) to occupy the same cabinet, outlet box, panel, or similar en- (2) Where the mobile home is supplied by cord and plug closure housing the electrical terminations of an electric light, 70-636 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 770--OPTICAL FI8ER CABLES AND RACEWAYS 770.154 power, Class 1, non—power-limited fire alarm, or medium- 770.154 Applications of Listed Optical Fiber Cables power network-powered broadband communications circuit. and Raceways. Nonconductive and conductive optical fi- Exc eption No. 1: Occupancy of the same cabinet, outlet ber cables shall comply with any of the requirements given in 770.154(A) through (D) and 770.154(F), or where cable box, panel, or similar enclosure shall be permitted where substitutions are made as shown in 770.154(E). nonconductive optical fiber cable is fiuu•tionall'associated with the electric light, power, Class 1, non—power-limited (A) Plenums.Cables installed in ducts,plenums, and other fire alarm, or medium-power network-powered broadband spaces used for environmental air shall be Type OFNP or communications circuit. OFCR Abandoned cables shall not be permitted to remain. Exception No. 2: Oc•cupanc}• of the same cabinet, outlet Types OFNR, OFCR, OFNG, OFN, OFCG, and OFC box, panel, or similar enclosure shall be permitted where cables installed in compliance with 300.22 shall be permit- nonconductive optical fiber cables are installed in fiu•tory- ted. Listed plenum optical fiber raceways shall be permitted or field-assembled control centers. to be installed in ducts and plenums as described in 300.22(B)and in other spaces used for environmental air as Exception No. 3: In industrial establishments moth, where described in 300.22(C). Only Type OFNP and OFCP cables conditions of maintenance and supervision ensure that onl qualified persons service the installation, nonconductive shall be permitted to be installed in these raceways. optical fiber cables shall be permitted with circuits exceed- (B) Riser. Cables installed in risers shall be as described in ing 600 volts. any of(B)(1), (13)(2), or (13)(3), Exception No. 4: In industrial establishments only, where (1) Cables in Vertical Runs. Cables installed in vertical conditions of maintenance and supervision ensure that only runs and penetrating more than one floor, or cables installed qualified persons service the installation, optical fibers in in vertical runs in a shaft, shall be Type OFNR or OFCR. composite optical fiber cables containing current-carrying Floor penetrations requiring Type OFNR or OFCR shall conductors operating over 600 volts shall be permitted to contain only cables suitable for riser or plenum use. Listed be installed. riser optical fiber raceways and listed plenum optical fiber Exception No. 5: Where all of the conductors of electric raceways shall also be permitted to be installed in vertical light, power, Class 1, nonpower-limited fire alarm, and riser runs in a shaft from floor to floor. Only Type OFNP, medium-power network powered broadband communica- OFCP, OFNR, and OFCR cables shall be permitted to be tions circuits are separated from all of the optical fiber installed in these raceways. cables by a permanent barrier or listed divider. (2) Metal Raceways or Fireproof Shafts. Type OFNG, (B) With Other Conductors. Optical fibers shall be per- OFN, OFCG, and OFC cables shall be permitted to be mitted in the same cable, and conductive and nonconduc- encased in a metal raceway or located in a fireproof shaft tive optical fiber cables shall be permitted in the same cable having firestops at each floor. tray, enclosure, or raceway with conductors of any of the (3) One- and`two-Family Dwellings. Type OFNG, OFN, following: OFCG, and OFC cables shall be permitted in one- and (1) Class 2 and Class 3 remote-control, signaling, and two-family dwellings. power-limited circuits in compliance with Article 725 FPN: See 300.21 for firestop requirements for Floor (2) Power-limited fire alarm systems in compliance with penetrations. Article 760 (3) Communications circuits in compliance with Article 800 (C) Other Cabling Within Buildings. Cables installed in building locations other than the locations covered in (4) Community antenna television and radio distribution 770.154(A) and (B) shall be Type OFNG, OFN, OFCG, or systems in compliance with Article 820 OFC. Such cables shall be permitted to be installed in listed (5) Low-power network-powered broadband communica- general-purpose optical fiber raceways, listed riser optical tions circuits in compliance with Article 830 fiber raceways, and listed plenum optical fiber raceways. (C) Support of Cables. Raceways shall be used for their (D) Cable Trays. Optical fiber cables of the types listed intended purpose.Optical fiber cables shall not be strapped, in Table 770.179 shall be permitted to be installed in taped, or attached by any means to the exterior Of any cable trays. Conduit or raceway as a means Of support. FPN: It is not the intent to require that these optical fiber Exception: Overhead(aerial) spans of optical fiber cables cables be listed specifically for use in cable trays. shall be permitted to be attached to the exterior of a (E) Cable Substitutions. The substitutions for optical fi- raceway-type mast intended for the attachment and support ber cables listed in Table 770.154(E) and illustrated in of such cables. Figure 770.154(E) shall be permitted. 2005 Edition NATIONAL ELECTRICAL CODE 70-637 770.179 ARTICLE 770—OPTICAL FIBER CABLES AND RACEWAYS Table 770.154(B) Cable Substitutions the fire-resistant characteristics capable of preventing the carrying of fire from floor to floor. Cable Type Permitted Substitutions FPN: One method of defining fire-resistant characteristics OFNP None capable of preventing the carrying of fire from floor to floor OFCP OFNP is that the cables pass the requirements of ANSI/UL 1666- OFNR OFNP 2002,Standard Test for Flame Propagation Height r f Elec•- OFCR OFNP, OFCP, OFNR trical and Optical-Fiber Cable Installed Vertically in OFNG, OFN OFNP, OFNR Shafts, OFCG, OFC OFNP, OFCP, OFNR, OFCR, OFNG, (C) Types OFNG and OFCG. Types OFNG and OFCG nonconductive and conductive general-purpose optical fiber cables shall be listed as being suitable for general-purpose Nonconductive conductive use,with the exception of risers and plenums, and shall also Plenum OFNP OFCP be listed as being resistant to the spread of fire. ----------- ----------- -------- FPN: One method of defining resistant to the spread offire is for the damage (char length) not to exceed 1.5 m (4 ft Riser OFNR OFCR I l in.) when performing the CSA"Vertical Flame Test-- Cables in Cable Trays," as described in CSA C22.2 No. ---------------- ----•-------- -------- 0.3-M-2001,Test Methods for Electrical Wires and Cables. General purpose OFNG OFCG (D) Types OFN and OFC. Types OFN and OFC noncon- OFN OFC ductive and conductive optical fiber cables shall be listed as A l3 Cable A shall be permitted to be used in place of cable B. being suitable for general-purpose use, with the exception of risers, plenums, and other spaces used for environmental Figure 770.154(E) Cable Substitution Hierarchy. air, and shall also be listed as being resistant to the spread of fire. (F) Hazardous (Classified) Locations. Cables installed in FPN: One method of defining resistant to the spread offire hazardous (classified) locations shall be any type indicated is that the cables do not spread fire to the top of the tray in in Table 770.154();). Cables Shall be sealed in accordance the"UL Flame Exposure, Vertical Tray Flame Test'in UL with the requirements of 501.15,502.15,505.16,or 506.16, 1685-2000, Standard for Safety for Vertical-Tray Ptopagation and Smoke-Releuse Pst for Electrical and applicable. Optical-Fiber Cables.The smoke measurements in the test method are not applicable. VI. Listing Requirements Another method of defining resistant to the spread of fire is for the damage(char length)not to exceed 1.5 m(4 ft 770.179 Optical Fiber Cables. Optical fiber cables shall I 1 in.) when performing the CSA"Vertical Flame Test— Cables in Cable Trays," as described in CSA C22.2 No. be listed in accordance with 770.174(A) through (D) and Q,3-M-2001, Test Methods for Electrical Wires and Cables. shall be marked in accordance with Table 770.179. FPN No. 1: Cables types are listed in descending order of (A) Types OFNP and OFCP. Types OFNP and OFCP fire resistance rating. Within each fire resistance rating, nonconductive and conductive optical fiber plenum cables nonconductive cable is listed first because it may substitute shall be listed as being suitable for use in ducts, plenums, for the conductive cable. and other space used for environmental air and shall also be FPN NQ. 2: See the referenced sections for requirements listed as having adequate fire resistant and low smoke pro- and permitted uses. ducing characteristics. 770.182 Optical Fiber Raceways. Optical fiber raceways FPN: One method of defining a cable that is low smoke shall be listed in accordance with 770.182(A) through (C). producing cable and fire-resistant cable is that the cable exhibits a maximum peak optical density of 0.5 or less, an (A) Plenum Optical Fiber Raceway. Plenum optical fiber average optical density of 0.15 or less, and a maximum flame spread distance of 1.52 m(5 ft)or less when tested in raceways shall be listed as having adequate fire-resistant accordance with NFPA 262-2007,Standard Method of Test and low smoke-producing characteristics. for Flatne Travel and Smoke of Wires and Cables for Use in Air-Handling Spaces. FPN: One method of defining that an optical fiber raceway is a low smoke producing raceway and a fire-resistant race- (B) Types OFNR and OFCR. Types OFNR and OFCR way is that the raceway exhibits a maximum peak optical nonconductive and conductive optical fiber riser cables density of 0.5 or less, an average optical density of 0.15 or less,and a maximum flame spread distance of 1.52 m(5 ft) shall be listed as being suitable for use in a vertical run in a or less when tested in accordance with the plenum test in shaft or from floor to floor and shall also be listed as having UL 2024, Standard for Optical Fiber Cable Raceway, 70-638 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 770—OPTICAL FIBER CABLES AND RACEWAYS 770.182 Table 770.179 Cable Markings (B) Riser Optical Fiber Raceway. Riser optical fiber raceways shall be listed as having fire-resistant characteris- Cable tics capable of preventing the carrying of fire from floor to Marking Type Reference floor. OFNP Nonconductive optical 770.179(A) and FPN: One method of defining fire-resistant characteristics fiber plenum cable 770.154(A) capable of preventing the carrying of fire from floor to floor OFCP Conductive optical 770.179(A) and is that the raceways pass the requirements of the test for fiber plenum cable 770.154(A) Flame Propagation(riser)in UL 2024,Standard for Optical OFNR Nonconductive optical 770.179(B) and Fiber Cable Raceiva.y. fiber riser cable 770.154(B) OFCR Conductive optical 770.179(B) and (C) General-Purpose Optical Fiber Cable Raceway. fiber riser cable 770.154110 General-purpose optical fiber cable raceway shall be listed OFNG Nonconductive optical 770.179(C) and as being resistant to the spread of fire. fiber general-purpose 770.154(C) cable FPN: One method of defining resistance to the spread of OFCG Conductive optical 770.179(0) and lire is that the raceways pass the requirements of the fiber general-purpose 770.154(C) Vertical-Tray Flame Test (General Use) in UL 2024, Stan- cable lard for Optical Fiber Cable Raceiva__v, OFN Nonconductive optical 770.179(D) and fiber general-purpose 770.154(C) cable OFC Conductive optical 770.179(D) and fiber general-purpose 770.154(C) cable 2008 Edition NATIONAL,ELECTRICAL CODE 70-639 CHAPTER 8 ARTICLE 800—COMMUNICATIONS CIRCUITS Chapter 8 Communications Systems radio), outside wiring for fire alarm and burglar alarm from ARTICLE 800 the communications utility to the customer's communica- Communications Circuits tions equipment up to and including terminal equipment such as a telephone, fax machine, or answering machine. FPN: Rules that are followed by a reference in brackets Communications Circuit Integrity (CI) Cable. Cable contain text that has been extracted from NFPA 90A-2002, used in communications systems to ensure continued op- Standard for the installation of Air-Conditioning and uen_ eration of critical circuits during a specified time under fire tilating Systents. Only editorial changes were made to the conditions. extracted text to make it consistent with this Code. Exposed (to Accidental Contact). A circuit that is in such a position that, in case of failure of supports or insulation, I. General contact with another circuit may result. 800.1 Scope. This article covers communications circuits FPN: See Article 100 for two other definitions of Exposed. and equipment. Point of Entrance. The point within a building at which FPN No. 1. For installation requirements for information the wire or cable emerges from an external wall, from a technology equipment and systems in an information tech- concrete floor slab, or from a rigid metal conduit (Type nology equipment room,see Article 6245. RMC) or an intermediate metal conduit (Type IMC) con- FPN No. 2: For further information for remote-control, nected by a grounding conductor to an electrode in accor- signaling,and power-limited circuits,See Article 725. dance with 800.100(B). FPN No.3: For further information for fire alarm systems, Premises. The land and buildings of a user located on the see Article 760. FPN No. 4: For installation requirements of optical fiber user side of the utility-user network point of demarcation. cables and raceways, see Article 770. Wire.A factory assembly of one or more insulated conduc- FPNNo.5: For installation requirements for network-power- tors without an overall covering, ed broadband communications circuits, see Article 830. 800.3 Other Articles. 800.2 Definitions.See Article 100. For the purposes of this (A) Hazardous (Classified) Locations. Communications article, the following additional definitions apply. circuits and equipment installed in a location that is classi- Abandoned Communications Cable. Installed communi- fied in accordance with 500.5 and 505.5 shall comply with cations cable that is not terminated at both ends at a con- the applicable requirements of Chapter 5. nector or other equipment and not identified for future use with a tag. (B) Equipment in Other Space Used for Environmental Air. Section 300.22(C) shall apply. FPN: See Article 100 for a definition of Equipment. (C) Network-Powered Broadband Communications Air Duct. A conduit or passageway for conveying air to or Systems. Article 830 shall apply to network-powered from heating, cooling, air conditioning, or ventilating broadband communications systems. equipment, but not including the plenum. [90A:3.3.51 800.18 Installation of Equipment. Equipment electrically Block. A square or portion of a city, town, or village en- connected to a telecommunications network shall be listed closed by streets and including the alleys so enclosed, but in accordance with 800.170. Installation of equipment shall not any street. also comply with 110.3(B). Cable. A factory assembly of two or more conductors hav- Exception: This listing requirement shall not apply to test ing an overall covering. equipment that is intended for temporary connection to a Cable Sheath. A covering over the conductor assembly telecommunications network by qualified persons during that may include one or more metallic members, strength the course of installation, maintenance, or repair of tele- members, or jackets. communications equipment or systems. Communications Circuit. The circuit that extends voice, 800.21 Access to Electrical Equipment Behind Panels audio, video, data, interactive services, telegraph (except Designed to Allow Access. Access to electrical equipment 70-640 NATIONAL.ELECTRICAL CODE 2008 Edition ARTICLE 800—COMMUNICATIONS CIRCUITS 800.47 shall not be denied by an accumulation of communications (A) On Poles and In-Span. Where communications wires wires and cables that prevents removal of panels, including and cables and electric light or power conductors are sup- suspended ceiling panels. ported by the same pale or are run parallel to each other in-span, the conditions described in 800.44(A)(1) through 800.24 Mechanical Execution of Work. Communications (A)(4) shall be met. circuits and equipment shall be installed in a neat and workmanlike manner. Cables installed exposed on the sur- (1) Relative Location. Where practicable, the communica- face of ceilings and sidewalls shall be supported by the tions wires and cables shall be located below the electric building structure in such a manner that the cable will not light or power conductors. be damaged by normal building use. Such cables shall be (2) Attachment to Cross-Arms. Communications wires secured by hardware, including straps, staples, cable ties, and cables shall not be attached to a cross-arm that carries hangers, or similar fittings designed and installed so as not electric light or power conductors. to damage the cable. The installation shall also conform to 300.4(D) and 300.11. (3) Climbing Space. The climbing space through commu- FPN: Accepted industry practices are described in nications wires and cables shall comply with the require- ANSI/NECA/BICSI 568-2006, .Standard for Installing meals of 225.14(D). Commercial Building Telecommunications Cabling; ANSIITIA/EIA-568-B.I-2004—Part 1, General Require- (4) Clearance. Supply service drops of 0-750 volts run- ments Commercial Building Telecommunications Cabling ning above and parallel to communications service drops Standard; ANSIrM-569-B-2004, Commercial Building shall have a minimum separation of 300 mm(12 in.) at any Standard for Telecommunications ParhtitiW and Spaces; point in the span, including the point of and at their attach- ANSIfITA-570-B, Residential Telecommunications Infra- ment to the building, provided the nongrounded conductors structure, and other ANSI-approved installation standards. are insulated and that a clearance of not less than 1.0 m 800.25 Abandoned Cables. The accessible portion of (40 in.) is maintained between the two services at the pole. abandoned communications cables sball be removed. (B) Above Roofs. Communications wires and cables shall Where cables are identified for future use with a tag,the tag have a vertical clearance of not less than 2.5 m (8 ft) from shall be of sufficient durability to withstand the environ- all points of roofs above which the ment involved. p y pass' Exception No. 1: Auxiliary buildings, such as garages and 800.26 Spread of Fire or Products of Combustion. In- the like. stallations of communications Cables and communications Exception No. 2: A reduction in clearance above only the raceways in hollow spaces, vertical shafts, and ventilation ovenc�rrrr,�itrg portion of the rno�'to not less than 450 mot or air-handling duets shall be made so that the possible (Ig In.) shall he permitted if(a) urrt more that 1.2 m (4 ft) spread Of fire or products Of combustion will not be sub- gf'conutnunications service-drop conductors pass above the stantially increased. Openings around penetrations of eom- roof overhang and(b) they are terminated at a through- or munications cables and communications raceways through fire-resistant-rated walls,partitions, floors, or ceilings shall above-tire-roof raceway or approved support. be firestopped using approved methods to maintain the fire Exception No. 3: Where the roof has a slope of not less resistance rating. than 100 num in 300 nurt (4 in. in 12 in.), a reduction in clearance to not less than 400 nun (3 ft)shall be permitted. FPN: Directories of electrical construction materials pub- lished by qualiW testing laboratories contain many listing FPN: For additional information regarding overhead wires installation restrictions necessary to maintain the fire- and cables, we ANSI C2-2007. National Electric, Safety resistive rating of assemblies where penetrations or open- Code, Part 2, Safety Rules for Overhead Lines. ings are made. Building codes also contain restrictions on membrane penetrations on opposite sides of a fire 800.47 Underground Circuits Entering Buildings. Un- resistanne-rated wall assembly.An example is the 600 mm der round communications wires and cables entering build- (24 in.)minimum horizontal:separation that usually applies g g between boxes installed on opposite sides of the wall.As- ings shall comply with 800.47(A) and (B). sistance in complying with$00.26 can be found in building codes, fire resistance directories,and product listings. (A) With Electric Light or Power Conductors. Under- ground communications wires and cables in a raceway, Ill. Wires and Cables Outside and Entering Buildings handhole enclosure, or manhole containing electric light, power, Class 1, or non-power-limited fire alarm circuit 800.44 Overhead Communications Wires and Cables. conductors shall be in a section separated from such con- Overhead communications wires and cables entering build- ductors by means of brick, concrete, or the partitions or by ings shall comply with 800.44(A) and (B). means of a suitable barrier. 2008 Edition NATIONAL ELECTRICAL CODF 70-64] 800.48 ARTICLE 800—COMMUNICATIONS CIRCUITS (B) Underground Block Distribution. Where the entire suits to a building from a cable having a grounded metal street circuit is run underground and the circuit within the sheath. block is placed so as to be free from the likelihood of accidental contact with electric light or power circuits of over (C} Entering Buildings. Where a primary protector is in- 300 volts to ground, the insulation requirements of 800.50(A) stalled inside the building, the communications wires and and (C) shall not apply, insulating supports shall not be re- cables shall enter the building either through a noncombus- quired for the conductors, and bushings shall not be required tible, nonabsorbent insulating bushing or through a metal where the conductors enter the building. raceway. The insulating bushing shall not be required where the entering communications wires and cables (1) $00.48 Unlisted Cables Entering Buildings. Unlisted are in metal-sheathed cable, (2) pass through masonry, (3) meet the requirements of $00.50(A) and fuses are omitted outside plant communications cables ShaII be permitted to as provided in 800.90(A)(1), or (4} meet the requirements be installed in locations as described in 800.154(C) where of 800.50(A) and are used to extend circuits to a building the length of the cable within the building, measured from from a cable having a grounded metallic sheath. Raceways its point of entrance, does not exceed IS m (50 ft) and the or bushings shall slope upward from the outside or, where cable enters the building from the outside and is terminated this cannot be done, drip loops shall be formed in the com- munications wires and cables immediately before they en- FPN No. 1: Splice cases or terminal boxes, both metallic ter the building. and plastic types,are typically used as enclosures for splic- Raceways shall be equipped with an approved service ing or terminating telephone cables. head. More than one communications wire and cable shall FPN No. 2: This section limits the length of unlisted out- be permitted to enter through a single raceway or bushing. side plant cable to 15 m (50 ft),while 800.90(B) requires Conduits or other metal raceways located ahead of the pri- that the primary protector be located as close as practicable mary protector shall be grounded. to the point at which the cable enters the building.There- fore,in installations requiring a primary protector,the out- 800.53 Lightning Conductors.Where practicable, a sepa- side plant cable may not be permitted to extend 15 m(50 ft) ration of at least 1.8 m (6 ft) shall be maintained between into the building if it is practicable to place the primary communications wires and cables on buildings and light- FPN closer than 15 m(50 ft) to the entrance point. g g FPN No. 3: See 800.2 for the definition of Point of Wing conductors. Entrance. III. Protection 800.50 Circuits Requiring Primary Protectors. Circuits 800,90 Protective Devices. that require primary protectors as provided in 800.90 shall comply with 800.50(A), (B), and (C). (A) Application. A listed primary protector shall be pro- vided on each circuit run partly or entirely in aerial wire or (A) insulation, Wires, and Cables. Communications aerial cable not confined within a block. Also, a listed pri- wires and cables without a metallic shield,running from the mary protector shall be provided on each circuit, aerial or last outdoor support to the primary protector, shall be listed underground, located within the block containing the build- in accordance with 800.173. ing served so as to be exposed to accidental contact with electric light or power conductors operating at over 300 (B) On Buildings. Communications wires and cables in volts to ground. In addition, where there exists a lightning accordance with 800.50(A) shall be separated at least exposure, each interbuilding circuit on a premises shall be 100 mm (4 in.) from electric light or power conductors not protected by a listed primary protector at each end of the in a raceway or cable or be permanently separated from interbuilding circuit. Installation of primary protectors shall conductors of the other system by a continuous and firmly also comply with 110.3(B). fixed nonconductor in addition to the insulation on the FPN No. 1: On a circuit not exposed to accidental contact wires, such as porcelain tubes or flexible tubing. Commu- with power conductors,providing a listed primary protector nications wires and cables in accordance with 800.50(A) in accordance with this article helps protect against other exposed to accidental contact with electric light and power hazards, such as lightning and above-normal voltages in- conductors operating at over 300 volts to ground and attached duced by fault currents on power circuits in proximity to to buildings shall be separated from woodwork by being sup- the communications circuit, ported on glass, porcelain, or other insulating material. FPN No. 2: Interbuilding circuits are considered to have a lightning exposure unless one or more of the following Exception: Separation front woodwork shall not be re- conditions exist: quired where fuses are omitted as provided for in (1) Circuits in large metropolitan areas where buildings are 800.90(A)(1), or where conductors are used to extend cir- close together and sufficiently high to intercept lightning. 70-642 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 800—COMMUNICATIONS CIRCUITS 800.93 (2) Interbuilding cable runs of 42 m (140 ft) or less, di- laled conductors safely fuse on all currents greater than the rectly buried or in underground conduit, where a con- current-carrying capacity of the primary protector and of the tinuous metallic cable shield or a continuous metallic primary protector grounding conductor conduit containing the cable is connected to each build- ing grounding electrode system. FPN: Section 9 of ANSI C2-2007, National Electrical (3) Areas having an average of five or fewer thunderstorm Safefp Code,provides an example of methods of protective days per year and earth resistivity of less than 100 grounding that can achieve effective grounding of telecom- ohm-meters. Such areas are found along the Pacific munications cable sheaths for cables from which commu- coast. nications circuits are extended. (1) Fuseless Primary Protectors. Fuseless-type primary (2) Fused Primary Protectors. Where the requirements protectors shall be permitted under any of the conditions listed under 800.90 A 1 ( )( )(a) through (A)(1)(e) are not met, given in (A)(1)(a) through (A)(1)(c). fused-type primary protectors shall be used. Fused-type pri- (a) Where conductors enter a building through a cable mary protectors shall consist of an arrester connected be- with grounded metallic sheath member(s) and where the tween each line conductor and ground, a fuse in series with conductors in the cable safely fuse on all currents greater each line conductor, and an appropriate mounting arrange- than the current-carrying capacity of the primary protector ment. Primary protector terminals shall be marked to indi- and of the primary protector grounding conductor cate line, instrument, and ground, as applicable. (b) Where insulated conductors in accordance with 800.50(A) are used to extend circuits to a building from a (B) Location. The primary protector shall be located in, cable with an effectively grounded metallic sheath mem- on, or immediately adjacent to the structure or building ber(s) and where the conductors in the cable or cable stub, served and as close as practicable to the point of entrance. or the connections between the insulated conductors and the plant exposed to accidental contact with electric light or FPN: See 800.2 for the definition of Point of Entrance. power conductors operating at greater than 300 volts to For purposes of this section, primary protectors located ground, safely fuse on all currents greater than the current- at mobile home service equipment located within 9.0 m carrying capacity of the primary protector, or the associated (30 ft) of the exterior wall of the mobile home it serves, or insulated conductors and of the primary protector ground- at a mobile home disconnecting means connected to an ing conductor electrode by a grounding conductor in accordance with (c) Where insulated conductors in accordance with 250.32 and located within 9.0 m (30 ft) of the exterior wall 800.50(A) or (B) are used to extend circuits to a building of the mobile home it serves, shall be considered to meet from other than a cable with metallic sheath member(s), the requirements of this section. where (1) the primary protector is listed as being suitable for this purpose for application with circuits extending from FPN: Selecting a primary protector location to achieve the other than a cable with metallic sheath members, and (2) shortest practicable primary protector grounding conductor helps limit potential differences between communications the connections of the insulated conductors to the plant circuits and other metallic systems. exposed to accidental contact with electric light or power conductors operating at greater than 300 volts to ground or (C) Hazardous (Classified) Locations. The primary pro- the conductors of the plant exposed to accidental contact tector shall not be located in any hazardous (classified) with electric light or power conductors operating at greater location as defined in 500.5 or in the vicinity of easily than 300 volts to ground safely fuse on all currents greater ignitible material. than the current-carrying capacity of the primary protector, Exception: As permitted in 501.150, 502.150, and 503.150, or associated insulated conductors and of the primary pro- tector grounding conductor (D) Secondary Protectors.Where a secondary protector is (d) Where insulated conductors in accordance with installed in series with the indoor communications wire and 800.50(A) are used to extend circuits aerially to a building cable between the primary protector and the equipment, it from a buried or underground circuit that is unexposed to shall be listed for the purpose in accordance with 800.170(B). accidental contact with electric light or power conductors FPN: Secondary protectors on circuits exposed to aeciden- operating at greater than 300 volts to ground tal contact with electric light or power conductors operating (e) Where insulated conductors in accordance with at greater than 300 volts to ground are not intended for use 800.50(A) are used to extend circuits to a building from cable without primary protectors. with an effectively grounded metallic sheath member(s), and where (1) the combination of the primary protector and insu- 800.93 Grounding or Interruption of Metallic .Sheath lated conductors is listed as being suitable for this purpose for Members of Communications Cables. Communications application with circuits extending from a cable with an etfec- cables entering the building or terminating on the outside of tively grounded metallic sheath member(s), and (2) the insu- the building shall comply with 800.93(A) or (B). 2008 Edition NATIONAL ELECTRICAL CODE 704A3 800.100 ARTICLE 800—COMMUNICATIONS CIRCUITS (A) Entering Buildings. In installations where the com- (5) Run in Straight Line. The grounding conductor shall munications cable enters a building, the metallic sheath be run to the grounding electrode in as straight a line as members of the cable shall:be either grounded as specified practicable. in 800.100 or interrupted by an insulating joint or equiva- lent device.The grounding or interruption shall be as close (6) Physical Protection.The grounding conductor shall be as practicable to the point of entrance. protected where exposed to physical damage. Where the grounding conductor is run in a metal raceway, both ends (B) Terminating on the Outside of Buildings. In instal- of the raceway shall be bonded to the grounding conductor lations where the communications cable is terminated on or the same terminal or electrode to which the grounding the outside of the building, the metallic sheath members of conductor is connected. the cable shall be either grounded as specified in 800.100 or interrupted by an insulating joint or equivalent device.The (B) Electrode. The grounding conductor shall be con- grounding or interruption sbaR be as close as practicable to nected in accordance with 800.1000)(1), (B)(2),or($)(3). the point of termination of the cable. (1) In Buildings or Structures with an Intersystem FPN: See 800.2 for a definition of Point of Entrance. Bonding Termination. If the building or structure served has an intersystem bonding termination, the grounding conductor Shall be connected to the intersystem bonding termination. IV. Grounding Methods (2) In Buildings or Structures with Grounding Means. 800.100 Cable and Primary Protector Grounding. The If the building or structure served has no intersystem bond- primary protector and the metallic member(s) of the cable ing termination, the grounding conductor shall be con- sheath shall be grounded as specified in 800.100(A) nected to the nearest accessible location on the following: through (D). (1) The building or structure grounding electrode system as covered in 250.50 (A) Grounding Conductor. (2) The grounded interior metal water piping system, (1) Insulation.The grounding conductor shall be insulated within 1.5 m (5 ft) from its point of entrance to the and shall be listed. building, as covered in 250.52 (3) The power service accessible means external to enclo- (2) Material. The grounding conductor shall be copper or sures as covered in 250.94 other corrosion-resistant conductive material, stranded or (4) The metallic power service raceway solid. (5) The service equipment enclosure (3) Size. The grounding conductor shall not be smaller (6) The grounding electrode conductor or the grounding than 14 AWG. electrode conductor metal enclosure (7) The grounding conductor or the grounding electrode of (4} Length. The primary protector grounding conductor a building or structure disconnecting means that is shall be as short as practicable. In one- and two-family grounded to an electrode as covered in 250.32 dwellings, the primary protector grounding conductor shall be as short as practicable, not to exceed 6.0 m (20 ft) in A bonding device intended to provide a termination length. point for the grounding conductor (intersystem bonding) shall not interfere with the opening of an equipment enclo- FPN: Similar grounding conductor length limitations ap- sure.A bonding device shall be mounted on non-removable plied at apartment buildings and commercial buildings help parts. A bonding device shall not be mounted on a door or to reduce voltages that may be developed between the building's power and communications systems during cover even if the door or cover is nonremovable. lightning events. For purposes of this section, the mobile home service equipment or the mobile home disconnecting means, as Exception: In one-and two family dwellings where it is not described in 800.90(B), shall be considered accessible. practicable to achieve an overall maximum primary protec- tor grounding conductor length of 6.0 m (20 ft), a separate (3) In Buildings or Structures Without Intersystem Bond- communications ground rod meeting the minimum dimen- ing Termination or Grounding Means. If the building or sional criteria of 800.100(8)(2)(2) .shall be driven, the pri- structure served has no intersystem bonding termination or mary protector shall be connected to the communications grounding means, as described in 800.100(13)(2), the ground- ground rod in accordance with 800.100(C), and the com- ing conductor shall be connected to either of the following: munications ground rod shall be connected to the power (1) To any one of the individual electrodes described in grounding electrode system in accordance with 800.100(D). 250.52(A)(1), (A)(2), (A)(3), or (A)(4) 70-644 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 800—COMMUNICATIONS CIRCUITS 800.133 (2) If the building or structure served has no intersystem V. Installation Methods Within Buildings bonding termination or has no grounding means, as described in 800.100(13)(2) or (13)(3)(1), to any one of 800.110 Raceways for Communications Wires and Cables. Where communications wires and cables are in- the individual electrodes described in 250.52(A)(7), stalled in a raceway, the raceway shall be either of a type and (A)(8) or to a ground rod or pipe not less than 1.5 permitted in Chapter 3 and installed in accordance with m (5 ft) in length and 12.7 mm ('h in.) in diameter, Chapter 3 or Isted plenum communications raceway,listed driven, where practicable, into permanently damp earth riser communications raceway, or fisted general-purpose and separated from lightning conductors as covered in communications raceway installed in accordance with 800.53 and at least 1.8 m(6 ft) from electrodes of other 800.154 and installed in accordance with 362.24 through systems. Steam or hot water pipes or air terminal con- 362.56, where the requirements applicable to electrical ductors (lightning-rod conductors) shall not he em- nonmetallic tubing apply. The raceway fill tables of Chap- played as electrodes for protectors. ter 3 and Chapter 9 shall not apply. (C) Electrode Connection. Connections to grounding 800.113 Installation of Communications Wires and electrodes shall comply with 250.70. Cables.Communications cables installed in buildings shall (D) Bonding of Electrodes. A bonding jumper not smaller be listed. than 6 AWG copper or equivalent shall be connected be- Exception: Communications cables that Comply with tween the communications grounding electrode and power 800.48 shall not be required to be listed. grounding electrode system at the building or structure • served where separate electrodes are used. 800.133 Installation of Communications Wires, Cables, and Equipment. Communications wires and cables from Exception: At mobile homes as covered in 800.106. the protector to the equipment or, where no protector is FPN No. l: See 250.60 for use of air tenninals (lightning required, communications wires and cables attached to the rods) outside or inside of the building shall comply with FPN Nn. 2: Bonding together of all separate electrodes 800.133(A) through (C). limits potential differences between them and between their (A) Separation from Other Conductors. associated wiring systems. (1) In Raceways, Cable Trays, Boxes, and Cables. 800.106 Primary Protector Grounding and Bonding at (a) Other Power-Limited Circuits. Communications Mobile Homes. cables shall be permitted in the same raceway,cable tray,or enclosure with cables of any of the following: and (A)(2}.Grounding.Grounding shall comply with 800.106(A)C1) (1) Class 2 and Class 3 remote-control, signaling, and and power-limited circuits in compliance with Article 725 (1) Where there is no mobile home service equipment lo- (2) power-limited fire alarm systems in compliance with Gated within 9.0 m (30 ft) of the exterior wall of the Article 760 mobile home it serves, the primary protector ground shall be connected to a grounding conductor in accor- (3) Nonconductive and conductive optical fiber cables in compliance with Article 770 dance with 800.100(B)(2). (4) Community antenna television and radio distribution (2) Where there is no mobile home disconnecting means systems in compliance with Article 820 grounded in accordance with 250.32 and located within 9.0 m (30 ft) of the exterior wall of the mobile home it {5) Low-power network-powered broadband communica- tions circuits in compliance with Article 830 serves,the primary protector ground shall be connected to a grounding conductor in accordance with 800.100(13)(2). (b) Class 2 and Class 3 Circuits, Class I circuits shall not be run in the same cable with communications circuits. (B) Bonding.The primary protector grounding terminal or Class 2 and Class 3 circuit conductors shall be permitted in grounding electrode shall be connected to the metal frame the same cable with communications circuits, in which case or available grounding terminal of the mobile home with a the Class 2 and Class 3 circuits shall be classified as com- copper grounding conductor not smaller than 12 AWG un- munications circuits and shall meet the requirements of this der either of the following conditions: article.The cables shall be listed as communications cables. (1) Where there is no mobile home service equipment or Exception: Cables constructed of individually, listed disconnecting means as in 800.106(A) Class 2, Class 3, and communications cables under a (2) Where the mobile home is supplied by cord and plug common jacket shall not be required to be classified as 2008 Edition NATIONAI.ELECTRICAL CODE 70-645 800.154 ARTICLE 800—COMMUNICATIONS CIRCUITS communications cable. The fire-resistance rating of the (C) Wiring in Ducts for Dust, Loose Stock, or Vapor composite cable shall be determined by the performance Removal. Section 300.22(A) shall apply. of the composite cable. (c) Electric Light, Power, Class 1, Nan-Power-Limited 800.154 Applications of Listed Communications Wires Fire Alarm, and Medium-Power Network-Powered Broad- and Cables and Communications Raceways. Communi- band Communications Circuits in Raceways, Compartments, cations wires and cables shall comply with the require- and Boxes. Communications conductors shall not be placed in ments of 800.154(A) through (D), 800.154(F), and any raceway,compartment,outlet box,junction box,or similar 800,154(G), or where cable substitutions are made in ac- fitting with conductors of electric light, power, Class I, non- cordance with 800.154(E). power-limited fire alarm, or medium-power network-powered broadband communications circuits. (A) Plenum. Cables installed in ducts, plenums, and other Exception No. 1: Where all of the conductors of electric spaces used for environmental air shall be Type CMP. light, power, Class 1, non-power-limited fire alann, and Abandoned cables shall not be permitted to remain. Types medium-power network-powered broadband communications CMP, CMR, CMG, CM, and CMX and communications circuits are separated front all of the conductors of conununi- wire installed in compliance with 300.22 shall be permitted. cations circuits by a permanent barrier or listed divider. Listed plenum communications raceways shall be permitted Exception No. 2: Power conductors in outlet boxes,junction to be installed in ducts and plenums as described in boxes, or similar fittings or compartments where such conduc- 300.22(B) and in other spaces used for environmental air as tors are introduced solely for power supply to communications described in 300.22(C). Only Type CMP cable shall be equipment. The power circuit conductors shall be routed permitted to be installed in raceways. within the enclosure to maintain a minimum of 6 mm(0,25 in.) separation from the communications circuit conductors. (B) Riser. Cables installed in risers shall comply with Exception No. 3: As permitted b y 620. 6. $00.154(B)(1), (6)(2), or (13)(3). (2) Other Applications.Communications wires and cables (1) Cables in Vertical Runs. Cables installed in vertical shall be separated at least 50 mm(2 in.) from conductors of runs and penetrating more than one floor,or cables installed any electric light, power, Class 1, non-power-limited fire in vertical runs in a shaft, shall be Type CMR. Floor pen- alarm, or medium-power network-powered broadband etrations requiring Type CMR shall contain only cables communications circuits. suitable for riser or plenum use. Listed riser communica- E.xception No. 1: Where either (1) all of the conductors of tions raceways and lusted plenum communications race- the electric light, power, Class 1, non-power-limited fire ways shall be permitted to be installed in vertical riser runs alarm, and medium-power network-powered broadband in a shaft from floor to floor. Only Type CMR and CMP communications circuits are in a raceway or in metal- cables shall be permitted to be installed in these raceways. sheathed, metal-clad, nonmetallic-sheathed, Type AC, or (2) Metal Raceways or Fireproof Shafts. Listed commu- Type OF cables, or (2) all of the conductors of conununi- nications cables shall be encased in a metal raceway or cations circuits are encased in raceway. located in a fireproof shaft having firestops at each floor. Exception No. 2: Where the communications wires and cables are permanendy separated from the conductors of (3) One-and Two-Family Dwellings.Type CM and CMX electric light,power, Class 1, non-power-limited fire alarm, cable shall be permitted in one- and two-family dwellings, and medium-power network-powered broadband Communi cations circuits by a continuous and firmly fixed noncon- p See 8pp.26 for firestop requirements for floor penetrations. doctor, such as porcelain tubes or flexible tubing, in addi- tion to the insulation on the wire. (C) Other Wiring Within Buildings. Cables installed in • (B) Support of Conductors. Raceways shall be used for building locations other than the locations covered in their intended purpose. Communications cables or wires 800.154(A), (B), (D), and (G) shall be in accordance with shall not be strapped, taped, or attached by any means to 800.154(0)(1) through (C)(6). the exterior of any conduit or raceway as a means of (1) General. Cables shall be Type CMG or Type CM. support. Listed communications general-purpose raceways, listed Exception: Overhead (aerial) .spans of communications riser communications raceways, and listed plenum commu- cables or wires shall be permitted to be attached to the nications raceways shall be permitted. Only Types CMG, exterior of a raceway-type mast intended far the attachment CM,CMR,or CMP cables shall be permitted to be installed and support of such conductors. in these communications raceways. 70-646 NATIONAL ELECTRICAL CODE 2009 Edition ARTICLE 800—COMMUNICATIONS CIRCUITS 800.170 (2) In Raceways. Listed communications wires that are Table 800.154(E) Cable Substitutions enclosed in a raceway of a type included in Chapter 3 shall be permitted. Cable Permitted ' W Use References Substitutions (3) Nonconcealed Spaces. Type CMX communications cable shall be permitted to be installed in nonconcealed spaces CMR Communications 800.154(B) CMP where the exposed length of cable does not exceed 3 m(10 tt), riser cable CMG. Communications 800.154(0)(1) CMP,CMR (4) One- and Two-Family Dwellings. Type CMX com- CM general-purpose munications cable less than 6 mm (0,25 in,) in diameter cable shall be permitted to be installed in one- and two-family CMX Communications 800,154(C) CNIR CMR, cable, limited CMG, CM dwellings. use (5) Multifamily Dwellings. Type CMX communications cable less than 6 mm (0.25 in.) in diameter shall be permit- Plenum V ted to be installed in nonconcealed spaces in multifamily --------------- dwellings. (6) Under Carpets.Type CMUC undercarpet communica- Riser CMR tions wires and cables shall be permitted to be installed --------------------------- under carpet. General purpose JMG (D) Cable Trays.Types CMP, CMR, CMG, and CM com-munications cables shall be permitted to be installed in ---------------- - ---- cable trays. Communications raceways, as described in Dwellings 800.182, shall be permitted to be installed in cable trays. (E) Cable Substitutions. The uses and substitutions for Type CM—Communications cables communications cables listed in Table 800.154(E) and il- ❑ Cable A shall be permitted to be used in place of cable B. lustrated in Figure 800.154(E) shall be permitted. e FPN: For information an Types CMP, CMR, CMG, CM. and CMX cables, see 500,179. Figure 800.154(E) Cable Substitution Hierarchy. (F) Hybrid Power and Communications Cable. Hybrid power and communications cable listed in accordance with fi)r Safety, Comnueniratirms Circuit Accessories. For infor- 800.179(H) shall be permitted to be installed in one- and mation on listing requirements for communications race- ways, see UL 2024-2004, Standard for Optical Fiber and two-family dwellings. Communication Cable Raceways. (G) Distributing Frames and Cross-Connect Arrays. (A) Primary Protectors.The primary protector shall con- Listed communications wire and Types CMP, CMR, CMG, sist of an arrester connected between each line conductor and CM communications cables shall be used in distribut- and ground in an appropriate mounting. Primary protector ing frames and cross-connect arrays. terminals shall be marked to indicate line and ground as 800.156 Dwelling Unit Communications Outlet.For new applicable. construction, a minimum of one communications outlet FPN: One way to determine applicable requirements for a shall be installed within the dwelling and cabled to the listed primary protector is to refer to ANSI/UL 497-1995, Standard for Protectors for Faired Conductor Communica- service provider demarcation point. tions Circuits. VI. Listing Requirements (B) Secondary Protectors. The secondary protector shall be listed as suitable to provide means to safely limit cur- 800.170 Equipment. Communications equipment shall be rents to less than the current-carrying capacity of listed listed as being suitable for electrical connection to a tele- indoor communications wire and cable, listed telephone set communications network, line cords, and listed communications terminal equipment determine applicable requirements is to FPN: One way to determine ports for external wire line communications circuits, refer to UL 60950-1-2003,Standard for Safety•of Informa- Any overvoltage protection, arresters,or grounding connec- tion Technology Equipment, UL 1459-1995, Standard far tion shall be connected on the equipment terminals side of Safe•n•, Telephone Equipment, or UL 1863-2004, Standard the secondary protector current-limiting means. 2008 Edition NATIONAL ELEC-rRICAL CODE 70647 800.173 ARTICLE 800—COMMUNICATIONS CIRCUITS FPN: One way to determine applicable requirements for a plenums, and other spaces used for environmental air and listed secondary protector is to refer to UL 497A-1996,Stan- shall also be listed as having adequate fire-resistant and low lard for Secondary Protectors for Communications Circuits. smoke-producing characteristics. 800.173 Drop Wire and Cable. Communications wires FPN: One method of defining a cable that is low smoke- and cables without a metallic shield, running from the last producing cable and fire-resistant cable is that the cable outdoor support to the primary protector, shall be listed as exhibits a maximum peak optical density of 0.5 or less,an being suitable for the purpose and shall have current-carrying average optical density of 0.15 or less, and a maximum flame spread distance of 1.52 m(5 ft)or less when tested in capacity as specified in 800.90(A)(1)(b) or (A)(I)(c). accordance with NFPA 262-2007,Standard Method of Test for Flame Travel and Smoke of Wires and Cables for Use in 800.179 Communications Wires and Cables. Communi- Air-Handling Spaces. cations wires and cables shall be listed in accordance with 800.179(A) through (1) and marked in accordance with (B) Type CMR. Type CMR communications riser cables Table 800.179. Conductors in communications cables, shall be listed as being suitable for use in a vertical run in a other than in a coaxial cable, shall be copper. shaft or from floor to floor and shall also be listed as having Communications wires and cables shall have a voltage fire-resistant characteristics capable of preventing the car- rating of not less than 300 volts. The insulation for the rying of fire from floor to floor. individual conductors, other than the outer conductor of a FPN; One method of defining lire-resistant characteristics ca- coaxial cable, shall be rated for 300 volts minimum. The pable of preventing the carrying of fire from floor to floor is cable voltage rating shall not be marked on the cable or on that the cables pass the requirements of ANSYUL 1666-2002, the undercatpet Communications wire. Communications Standard Test for Flarne Propagation Height of Electrical and wires and cables shall have a temperature rating of not Iess Optical-Fiber Cable Installed Vertically in Shafts. than 60°C. (C) Type CMG. Type CMG general-purpose communica- Exception: Voltage markings shall be permitted where the tions cables shall be listed as being suitable for general- cable has multiple listings and voltage marking is required purpose communications use, with the exception of risers for one or more of the listings. and plenums, and shall also be listed as being resistant to FPN No. 1: Voltage markings on cables may be Msinter- the spread of fire. preted to suggest that the cables may be Suitable for Class FPN: One method of defining resistant to the spread cffire 1,electric light, and power applications. is for the damage (char length) not to exceed 1.5 m (4 ft FPN No. 2: See 800.170 for listing requirement for 11 in.) when performing the CSA"Vertical Flame Test— Cables in Cable Trays," as described in CSA C22.2 No. equipment. 0.3-M-2001, Test Methods for Electrical Wires and Cables. Table 800.179 Cable Markings (D) Type CM. Type CM communications cables shall be Cable Marking Type Reference listed as being suitable for general-purpose communica- tions use, with the exception of risers and plenums, and CMP Communications 800.179(A) and shall also be listed as being resistant to the spread of fire. plenum cable 800.154(A) CMR Communications 800.179(B) and FPN: One method of defining resistant to the spread of fire riser cable 800.154(B) is that the cables do not spread fire to the top of the tray in CMG Communications 800.179(C)and the "UL Flame Exposure, Vertical Flame Tray Test"in LIL general-purpose 800.154(C)(1) and 1685-2000, Standard for Safety for Vertical-Tray Fire- cable (D) Propagation and SmcAe-Release Test fpr Electrical and CM Communications 800.179(D) and Optical-Fiber Cables.The smoke measurements in the test general-purpose 800.154(C)(1) and method are not applicable. cable (D) Another method of defining resistant to the spread of fire CMX Communications 800.179(E) and is for the damage(char length)not to exceed 1.5 m(4 ft 11 in.) cable, limited use 800.154(C)(2), (3), when performing the CSA"Vetical Flame Test—Cables in (4), and (5) Cable Trays," as described in CSA C22.2 No. 0.3-M-2001, CMUC Undercarpet 800.179(F) and Test Methods for Electrical Wires and Cables. communications 800.154(C)(6) wire and cable (E) Type CMX. Type CMX limited-use communications cables shall be listed as being suitable for use in dwellings FPN No. 1: Cable types are listed in descending order of and for use in raceway and shall also be listed as being fire resistance rating. resistant to flame spread. FPN No.2: See the referenced sections for permitted uses. FPN: One method of determining that cable is resistant to flame spread is by testing the cable to the VW-1 (vertical- (A) Type CMP. Type CMP communications plenum wire) flame test in ANSVUL 1581-2001, Reference Stan- cables shall be listed as being suitable for use in ducts, dard for Electrical Wires, Cables and Flexible Cords. 7"8 NATIONAL ELECTRICAL CODL 21708 Edition ARTICLE 810—RADIO AND TELEVISION EQUIPMENT 810.3 (F) Type CMUC Underearpet Wires and Cables. Type (A) Plenum Communications Raceways. Plenum com- CMUC undercarpet communications wires and cables shall munications raceways listed as plenum optical fiber race- be listed as being suitable for undercarpet use and shall also ways shall be permitted for use in ducts,plenums,and other be listed as being resistant to flame spread. spaces used for environmental air and shall also be listed as FPN: One method of determining that cable is resistant to having adequate fire-resistant and low smoke-producing flame spread is by testing the cable to the VW-1 (vertical- characteristics. wire) flame test in ANSI/UL 1581-1991, Reference Stan- dard for Electrical Wires, Cables and Flexible Cords. FPN: One method of defining that an optical fiber raceway is a low smoke producing raceway and a fire-resistant race- (G) Communications Circuit Integrity (Cl) Cables. way is that the raceway exhibits a maximum peak optical Cables suitable for use in communications systems to en- density of 0.5 or less, an average optical density of 0.15 or sure survivability of critical circuits during a specified time less,and a maximum flame spread distance of 1.52 m(5 ft) under fire conditions shall be listed as circuit integrity (CI) or less when tested in accordance with the plenum test in cable. Cables identified in 800.179(A) through (E) that UL 2024, Standard for Optical Fiber Cable Racew'af. meet the requirements for circuit integrity shall have the (B) Riser Communications Raceways.Riser communica- additional classification using the suffix "Cl." tions raceways shall be listed as having adequate fire- FPN: One method of defining circuit integrity(Cl)cable is resistant characteristics capable of preventing the carrying by establishing a minimum 2-hour fire resistance rating for of fire from floor to floor. the cable when tested in accordance with UL 2196-1995, Standard for Tests of Fire Resistive Cables. FPN: One method of defining fire-resistant characteristics capable of preventing the carrying of fire from floor to floor (H) Communications Wires. Communications wires, is that the raceways pass the requirements of the test for such as distributing frame wire and jumper wire, shall be Flame Propagation(riser)in UL 2024,Standard far Optical listed as being resistant to the spread of fire. Fiber Cable Raceway. FPN: One method of defining resistant to the spread of fire is that the cables do not spread fire to the top of the tray in (C) General-Purpose Communications Raceways. Gen- the "UL Flame Exposure,Vertical Flame Tray Test"in UL eral-purpose communications raceways shall be listed as 1685-2000, Standard for Safety for Vertical-Tray Fire- being resistant to the spread of fire. Propagation and Smoke-Release Test for Electrical and Optical-Fiber Cables.The Smoke measurements in the test FPN: One method of defining resistance to the spread of method are not applicable. fire is that the raceways pass the requirements of the Another method of defining resistant to the spread of Vertical-Tray Flame Test (General Use) in UL 2024, Stan- fire is for the damage(char length)not to exceed 1.5 m(4 ft Bard for Optical Fiber Cable Raceway. i l in.) when performing the CSA"Vertical Flame Test— Cables in Cable Trays," as described in CSA C22.2 No. 0.3-M-2001, Test Methods for Electrical Wires and Cables. (I) Hybrid Power and Communications Cables. Listed ARTICLE 8X0 hybrid power and communications cables shall be permit- ted where the power cable is a listed Type NM or NM-B Radio and Television Equipment conforming to the provisions of Article 334, and the com- munications cable is a listed Type CM, the jackets on the I. General listed NM or NM-B and listed CM cables are rated for 600 volts minimum, and the hybrid cable is listed as being 810.2 Scope. This article covers antenna systems for radio resistant to the spread of fire, and television receiving equipment, amateur radio transmit- FPN: One method of defining resistant to the spread of fire ting and receiving equipment, and certain features of trans- is that the cables do not spread fire to the top of the tray in mitter safety. This article covers antennas such as multi- the"UL Flame Exposure, Vertical Flame Fray Test"in UL element, vertical rod, and dish, and also covers the wiring 1685-2000, Standard for Safety for Vertical-Tray Fire- and cabling that connects them to equipment. This article Propagation and Smoke-Release lest for Electrical arul Optical-Fiber Cables.The smoke measurements in the test does not cover equipment and antennas used for coupling method are not applicable, carrier current to power line conductors. Another method of defining resistant to the spread of fire is for the damage(char length)not to exceed 1.5 m(4 ft 810.2 Definitions. For definitions applicable to this article, I 1 in.) when performing the GSA"Vertical Flame Test— see Article 100. Cables in Cable Trays," as described in CSA C22.2 No. 0.3-M-2001, Test Methods for Electrical Wires and Cables. 820.3 Other Articles. Wiring from the source of power to 800.182 Communications Raceways. Communications and between devices connected to the interior wiring sys- raceways shall be listed in accordance with 800.182(A) tem shall comply with Chapters 1 through 4 other than as through (C), modified by Parts I and II of Article 640. Wiring for audio 2008 Edition NATIONAL ELECTRICAL CODE 70-649 810.4 ARTICLE 910—RADIO AND TELEVISION EQUIPMENT signal processing, amplification, and reproduction equipment 810.16 Size of Wire-Strung Antenna—Receiving Station. shall comply with Article 640. Coaxial cables that connect antennas to equipment shat] comply with Article 820. (A) Size of Antenna Conductors. Outdoor antenna con- ductors for receiving stations shall be of a size not less than 810.4 Community Television Antenna.The antenna shall given in Table 810.16(A). comply with this article.The distribution system shall com- Table 810.16(A) Size of Receiving Station Outdoor Antenna ply with Article 820. Conductors 810.5 Radio Noise Suppressors. Radio interference elimi- Minimum Size or Conductors (AWG) nators, interference capacitors, or noise suppressors con- Where Maximum Open Span Length Is nected to power-supply leads shall be of a listed type.They 11 m to shall not be exposed to physical damage. Less Than 45 m (35 ft Over 45 In Material 11 m (35 ft) to 150 ft) (150 ft) 11I. Receiving Equipment—Antenna Systems Aluminum alloy, 19 14 12 hard-drawn 810.11 Material. Antennas and lead-in conductors shall be copper of hard-drawn copper, bronze, aluminum alloy, copper-clad Copper-clad 20 17 14 steel, or other high-strength, corrosion-resistant material. steel, bronze, or other Exception: Soft-drawn or medium-drawn copper shall be high-strength permitted for lead-in conductors where the muuintum span material between points of.support is less than 11 m (35 ft). (B) Self-Supporting Antennas. Outdoor antennas, such as 810.12 Supports. Outdoor antennas and lead-in conduc- vertical rods, dishes, or dipole structures, shall be of tors shall be securely supported. The antennas or lead-in corrosion-resistant materials and of strength suitable to conductors shall not be attached to the electric service mast. withstand ice and wind loading conditions and shall be They shall not be attached to poles or similar structures located well away from overhead conductors of electric carrying open electric light or power wires or trolley wires light and power circuits of over 150 volts to ground, so as of over 250 volts between conductors. Insulators supporting to avoid the possibility of the antenna or structure falling the antenna conductors shall have sufficient mechanical into or making accidental contact with such circuits. strength to safely support the conductors. Lead-in conduc- tors shall he securely attached to the antennas. 810.17 Size of Lead-in — Receiving Station. Lead-in conductors from outside antennas for receiving stations 810.13 Avoidance of Contacts with Conductors of shall, for various maximum open span lengths, be of such Other Systems. Outdoor antennas and lead-in conductors size as to have a tensile strength at least as great as that of from an antenna to a building shall not cross over open the conductors for antennas as specified in 810.16. Where conductors of electric light or power circuits and shall be the lead-in consists of two or more conductors that are kept well away from all such circuits so as to avoid the twisted together, are enclosed in the same covering, or are possibility of accidental contact. Where proximity to open concentric, the conductor size shall, for various maximum electric light or power service conductors of less than 250 open span lengths, be such that the tensile strength of the volts between conductors cannot be avoided, the installa- combination is at least as great as that of the conductors for tion shall be such as to provide a clearance of at least antennas as specified in 810.16. 600 mm (2 ft). Where practicable, antenna conductors shall be in- 810.18 Clearances — Receiving Stations. stalled so as not to cross under open electric light or power (A) Outside of Buildings. Lead-in conductors attached to conductors. buildings shall be installed so that they cannot swing closer than 600 mm(2 ft)to the conductors of circuits of 250 volts 810.14 Splices. Splices and joints in antenna spans shall be or less between conductors, or 3.0 m (10 ft) to the conduc- made mechanically secure with approved splicing devices tors of circuits of over 250 volts between conductors, ex- or by such other means as will not appreciably weaken the cept that in the case of circuits not over 150 volts between conductors. conductors, where all conductors involved are supported so as to ensure permanent separation, the clearance shall be 810.15 Grounding. Masts and metal structures supporting permitted to be reduced but shall not be less than 100 mm antennas shall be grounded in accordance with 810.21. (4 in.). The clearance between lead-in conductors and any 70-650 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 810—RADIO AND TELEVISION EQUIPMENT 810.21 conductor forming a pan of a lightning protection system point of entrance of the lead-in and the radio set or trans- shall not be less than 1.8 m (6 ft). Underground conductors formers and as near as practicable to the entrance of the shall be separated at least 300 mm(12 in.) from conductors conductors to the building.The antenna discharge unit shall of any light or power circuits or Class 1 circuits. not be located near combustible material or in a hazardous Exception: Where the electric light or power- conductors, (classified) location as defined in Article 500. Class I conductors, or lead-in conductors are installed in (C) Grounding. The antenna discharge unit shall be raceways or metal cable armor grounded in accordance with 810.21. FPN No. 1: See 250.60 for use of air terminals.For further information, see NFPA 780-2008, Standard for the Instal- lation of Lightning Protection Systems, which contains de- Grounding conductors shall comply with 810.21(A) tailed information on grounding, bonding, and spacing through (K). from lightning protection systems. FPN No.2: Metal raceways,enclosures,frames,and other (A) Material.The grounding conductor shall be of copper, non--current-carrying metal parts of electrical equipment in- aluminum, copper-clad steel, bronze, or similar corrosion- stalled on a building equipped with a lightning protection resistant material. Aluminum or copper-clad aluminum system may require bonding or spacing from the lightning grounding conductors shall not be used where in direct protection conductors in accordance with NFPA 780-2008, contact with masonry or the earth or where subject to cor- Standard for the Installation of Lightning Protection Sys- rosive conditions. Where used outside, aluminum or tems. Separation from lightning protection conductors is typically 1.8 m(6 ft)through air or 900 mm(3 ft)through copper-clad aluminum shall not be installed within 450 mm dense materials such as concrete,brick, or wood. (18 in.) of the earth. (B) Antennas and Lead-ins — Indoors. Indoor antennas (B) Insulation. Insulation on grounding conductors shall and indoor lead-ins shall not be run nearer than 50 mm (2 in.) not be required. to conductors of other wiring systems in the premises. (C) Supports. The grounding conductors shall be securely Exception No. 1: Where such other conductors are in fastened in place and shall be permitted to be directly at- metal raceways or cable armor tached to the surface wired over without the use of insulat- Exc eption No. 2: Where permanently separated from such ing supports. other conductors by a continuous and firntly fixed noncan- Exception: Where proper support cannot be provided, the ductor, such as porcelain rubes or flexible tubing. size of the grounding conductors shall be increased (C) In Boxes or Other Enclosures. Indoor antennas and proportionatel.. indoor lead-ins shall be permitted to occupy the same box (D) Mechanical Protection. The grounding conductor or enclosure with conductors of other wiring systems where shall be protected where exposed to physical damage. separated from such other conductors by an effective per- Where the grounding conductor is run in a metal raceway, manently installed barrier. both ends of the raceway shall be bonded to the grounding conductor or to the same terminal or electrode to which the 810.19 Electrical Supply Circuits Used in Lieu of An- grounding conductor is connected. tenna — Receiving Stations. Where an electrical supply circuit is used in lieu of an antenna,the device by which the (E) Run in Straight Line.The grounding conductor for an radio receiving set is connected to the supply circuit shall antenna mast or antenna discharge unit shall be run in as be listed, straight a line as practicable from the mast or discharge unit to the grounding electrode. 810.20 Antenna Discharge Units — Receiving Stations. (F) Electrode. The grounding conductor shall be con- (A) Where Required. Each conductor of a lead-in from an nected as required in (17)(1) through (F)(3). outdoor antenna shall be provided with a listed antenna discharge unit. (1) In Buildings or Structures with an Intersystem Bond- ing Termination. If the building or structure served has an Exception: Where the lead-in conductors are enclosed in a intersystem bonding termination, the grounding conductor continuous metallic shield that either is grounded with a Shall be connected to the intersystem bonding termination. conductor in accordance with 810.21 or is protected by an antenna discharge unit. (2) In Buildings or Structures with Grounding Means. If the building or structure served has no intersystem (B) Location. Antenna discharge units shall be located bonding termination, the grounding conductor shall be con- outside the building or inside the building between the nected to the nearest accessible location on the following: 2008 Edition NATIONAL ELECTRICAL CODE 70-651 810.51 ARTICLE 814—RADIO AND TELEVISION EQUIPMENT (1) The building or structure grounding electrode system 810.52 Size of Antenna. Antenna conductors for transmit- as covered in 250.50 ting and receiving stations shall be of a size not less than (2) The grounded interior metal water piping systems, given in Table 810.52. within 1.52 m (5 ft) from its point of entrance to the building, as covered in 25D.52 Table 810.52 Size of Amateur Station Outdoor Antenna Conductors (3) The power service accessible means external to the building, as covered in 250.94 Minimum Size of Conductors (AWG) (4) The metallic power service raceway Where Maximum Open Span Length (5) The service equipment enclosure, or Is (6) The grounding electrode conductor or the grounding Less Than 45 m electrode conductor metal enclosures Material (150 ft) Over 45 m (150 rt) A bonding device intended to provide a termination Hard-drawn copper 14 10 point for the grounding conductor (intersystem bonding) Copper-clad steel, 14 12 shall not interfere with the opening of an equipment enclo- bronze, or other sure.A bonding device shall be mounted on non-rem m ovable ateritrength material parts.A bonding device shall not be mounted on a door or cover even if the door or cover is non-removable. 810.53 Size of Lead-in Conductors. Lead-in conductors (3) In Buildings or Structures Without Intersystem for transmitting stations shall, for various maximum span Bonding Termination or Grounding Means. If the build- lengths, be of a size at least as great as that of conductors ing or structure served has no intersystem bonding fermi- for antennas as specified in 810.52. nation or grounding means, as described in 810.21(F)(1). (1) To any one of the individual electrodes described in 810.54 Clearance on Building. Antenna conductors for 250.52; or transmitting stations, attached to buildings, shall be firmly (2) If the building or structure served has no grounding mounted at least 75 mm (3 in.) clear of the surface of the means, as described in 810.21(F)(1) or (F)(2), to an building on nonabsorbent insulating supports, such as effectively grounded metal structure. treated pins or brackets equipped with insulators having not less than 75-mm (3-in.) creepage and airgap distances. (G) Inside or Outside Building.The grounding conductor Lead-in conductors attached to buildings shall also comply shall be permitted to be run either inside or outside the with these requirements. building. Exception: Where the lead-in conductors are enclosed in a (H) Size. The grounding conductor shall not be smaller continuous metallic shield that is grounded with a ConduC- than AWG copper, 8 AWG aluminum, or 17 AWG for in accordance with 810.58, they shall not be required to capper r--clad steel or bronze. comply with these requirements. Where grounded, the me- (I) Common Ground. A single grounding conductor shall tallic shield shall also be permitted to be used as a be permitted for both protective and operating purposes. conductor. (J) Bonding of Electrodes. A bonding jumper not smaller 810.55 Entrance to Building. Except where protected than 6 AWG copper or equivalent shall be connected be- with a continuous metallic shield that is grounded with a tween the radio and television equipment grounding elec- conductor in accordance with 810.58, lead-in conductors trode and the power grounding electrode system at the for transmitting stations shall enter buildings by one of the building or structure served where separate electrodes are following methods: used. (1) Through a rigid,noncombustible,nonabsorbent insulat- (K) Electrode Connection. Connections to grounding ing tube or bushing electrodes shall comply with 250.70. (2) Through an opening provided for the purpose in which the entrance conductors are firmly secured so as to provide a clearance of at least 50 mm (2 in.) III. Amateur Transmitting and Receiving Stations — (3) Through a drilled window pane Antenna Systems 810.51 Other Sections. In addition to complying with Part 810.56 Protection Against Accidental Contact. Lead-in III, antenna systems for amateur transmitting and receiving conductors to radio transmitters shall be located or installed stations shall also comply with 8 10.11 through 810.15. so as to make accidental contact with them difficult. 70-152 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 820—COMMUNITY ANTENNA TELEVISION AND RADIO DISTRIBUTION SYSTEMS 820,2 810.57 Antenna Discharge Units — Transmitting Sta- (C) Interlocks on Doors. All access doors shall be pro- tions. Each conductor of a lead-in for outdoor antennas shall vided with interlocks that disconnect all voltages of over be provided with an antenna discharge unit or other suitable 350 volts between conductors when any access door is means that drain static charges from the antenna system. opened. Exception No. 1: Where the lead-in is protected by a con- tinuous metallic shield that is grounded with a conductor in accordance with 810.58, an antenna discharge unit or other suitable means shall not be required. ARTICLE 820 Exception No. 2: Where the antenna is grounded with a Community Antenna Television conductor in accordance with 810.58, an antenna dis- and Radio Distribution Systems charge unit or other suitable means shall not be require& 510.58 Grounding Conductors — Amateur Transmit- FPN: Rules that are followed by a reference in brackets ting and Receiving Stations. Grounding conductors shall contain text that has been extracted from NFPA 90A-2002, comply with 810.58(A) through (Q. Standard for the Installation of Air-Conditioning and Ven- tilating .yvstetns. Only editorial changes were made to the (A) Other Sections.All grounding conductors for amateur extracted text to make it consistent with this Code. transmitting and receiving stations shall comply with 810.21(A) through (K). I. General (B) Size of Protective Grounding Conductor. The pro- 820.1 Scope. This article covers coaxial cable distribution tective grounding conductor for transmitting stations shall of radio frequency signals typically employed in commu- be as large as the lead-in but not smaller than 10 AWG nity antenna television (CATV) systems. copper, bronze, or copper-clad steel. 820.2 Definitions.See Article 100.For the purposes of this (C) Size of Operating Grounding Conductor. The oper- article, the following additional definitions apply. ating grounding conductor for transmitting stations shall Abandoned Coaxial Cable. Installed coaxial cable that is not be less than 14 AWG copper or its equivalent. not terminated at equipment other than a coaxial connector and not identified for future use with a tag. IV. Interior Installation — Transmitting Stations FPN: See ArEicte 100 for a definition of Equipment. 510.70 Clearance from Other Conductors. All conduc- tors inside the building shall be separated at least 100 mm Air Duct. A conduit or passageway for conveying air to or (4 in.) from the conductors of any electric light, power, or from heating, cooling, air conditioning, or ventilating signaling circuit. equipment, but not including the plenum. [90A:3.3.5] Exception No. 1: As provided in Article 640. Coaxial Cable.A cylindrical assembly composed of a con- ductor centered inside a metallic tube or Shield, separated Exception No. 2: Where separated from other conductors by a dielectric material, and usually covered by an insulat- by raceway or some firmly fixed nonconductor, such as ing jacket. Porcelain tubes or flexible tubing. Exposed (to Accidental Contact). A circuit in such a po- 810.71 General. Transmitters shall comply with sition that, in case of failure of supports and or insulation, 810.71(A) through (C). contact with another circuit may result. (A) Enclosing.The transmitter shall be enclosed in a metal FPN: See Article 100 for two other definitions of Exposed. frame or grille or separated from the operating space by a Point of Entrance. The point within a building at which barrier or other equivalent means, all metallic parts of the coaxial cable emerges from an external wall, from a which are effectively connected to a grounding conductor, concrete floor slab, or from a rigid metal conduit (Type (B) Grounding of Controls. All external metal handles RMC) or an intermediate metal conduit (Type IMC) con- nected by a grounding conductor to an electrode in accor- and controls accessible to the operating personnel shall be dance with 520.100($). effectively connected to an equipment grounding conductor if the transmitter is powered by the premises wiring system Premises. The land and buildings of a user located on the or grounded with a conductor in accordance with 810.21. user side of utility-user network point of demarcation. 2008 Edition NATIONAL ELECTRICAL CODE 70-653 820.3 ARTICLE 820—COMMUNITY ANTENNA TELEVISION AND RADIO DISTRIBUTION SYSTEMS 820,3 Other Articles. Circuits and equipment shall com- FPN: Accepted industry practices are described in ply with 820.3(A) through (C). ANSIINECAIBICSI 568-2006, Standard far Installing Commercial Building Telecommunications Cabling;ANS'll (A) Hazardous (Classified) Locations. CATV equipment TIAIEIA-568-B.1 2004 —Part 1, General Requirements installed in a location that is classified in accordance with Commercial Building Telecommunications Cabling Stan- 500.5 shall comply with the applicable requirements of dard; ANSTfrIA-569-B 2004, Commercial Building Stan- dard for Telecommunications Pathways and Spaces; Chapter 5. ANSIMA-570-B, Residential Telecommunications infra- (B) Ducts, Plenums, and Other Air-Handling Spaces. structure, and other ANSI-approved installation standards. Section 300.22, where installed in ducts, plenums, or other spaces used for environmental air, shall apply. 820.25 Abandoned Cables. The accessible portion of abandoned coaxial cables shall be removed. Where cables Exception: As permitted in 820.154(A). are identified for future use with a tag, the tag shall be of (C) Installation and Use. Section 110.3 shall apply. sufficient durability to withstand the environment involved. (D) Installations of Conductive and Nonconductive Op- 820,26 Spread of Fire or Products of Combustion. In- tical Fiber Cables. Article 770 shall apply. stallations of coaxial Cables and CATV raceways in hollow spaces,vertical shafts, and ventilation or air-handling ducts (E) Communications Circuits. Article 800 shall apply. shall be made so that the possible spread of fire or products (F) Network-Powered Broadband Communications of combustion will not be substantially increased.Openings Systems. Article 830 shall apply. around penetrations of coaxial cables and CATV raceways through fire-resistant-rated walls, partitions, floors, or cei'l- (G) Alternate Wiring Methods. The wiring methods of ings shall be firestopped using approved methods to main- Article 830 shall be permitted to substitute for the wiring tain the fire resistance rating. methods of Article 820, FPN: Directories of electrical construction materials FPN: Use arArticle 830 wiring methods will facilitate the published by qualified testing laboratories contain many upgrading of Article 820 installations to network-powered listing installation restrictions necessary to maintain the broadband applications. fire-resistive rating of assemblies where penetrations or openings are made. Building codes also contain: restric- 820.15 Power Limitations. Coaxial cable shall be permit- tions on membrane penetrations on opposite sides of a ted to deliver power to equipment that is directly associated fire resistance-rated wail assembly. An example is the with the radio frequency distribution system if the volt- 600- (24-1n.) minimum horizontal separation that age is not over 60 volts and if the current is supplied by usually applies between boxes installed on opposite sides of the wall.Assistance in complying with 820.26 can be a transformer or other device that has power-limiting found in building codes, fire resistance directories, and characteristics. product listings. Power shall be blocked from premises devices on the network that are trot intended to be powered via the coaxial cable. Ill.. Coaxial Cables Outside and Entering Buildings 820.21 Access to Electrical Equipment Behind Panels 820.44 Overhead Coaxial Cables.Coaxial cables,prior to Designed to Allow Access. Access to electrical equipment the point of grounding, as defined in 820.93, shall comply shall not be denied by an accumulation of coaxial cables with 820.44(A) through (F). that prevents removal of panels, including suspended ceil- ing panels. (A) On Poles, Where practicable, conductors on poles shall be located below the electric light, power, Class 1, or 820.24 Mechanical Execution of Work. Community tele- non-power-limited fire alarm circuit conductors and shall vision and radio distribution systems shall be installed in a not be attached to a cross-arm that carries electric light or neat and workmanlike manner. Coaxial cables installed ex- power conductors. posed on the surface of ceiling and sidewalls shall be sup- ported by the building structure in such a manner that the (B) Lead-in Clearance. Lead-in or aerial-drop coaxial cables will not be damaged by normal building use. Such cables from a pole or other support, including the point of cables shall be secured by hardware including straps, initial attachment to a building or structure, shall be kept staples, cable ties, hangers, or similar fittings designed and away from electric light, power, Class 1, or non--power- installed so as not to damage the cable. The installation limited fire alarm circuit conductors so as to avoid the pos- shall also conform to 300.4(D) and 300.11. sibility of accidental contact. 70-654 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 820—COMMUNITY ANTENNA 7ELEVISION AND RADIO DISTRIBUTION SYSTEMS 820.93 Exception: Where proximity to electric light, power, Class (2) Other Communications Systems. Coaxial cable shall 1, or non-power-limited fire alarm circuit .service conduc- be installed so that there will be no unnecessary interfer- tors cannot be avoided, the installation shall be such as to ence in the maintenance of the separate systems. In no case provide clearances of not less than 300 min (12 in.)from shall the conductors, cables, messenger strand, or equip- light, power, Class 1, or non-power-limited fire alarm cir- meat of one System cause abrasion to the conductors,cable, c•uit service drops. The clearance requirement shall apply messenger strand, or equipment of any other system. at all points along the drop, and it shall increase to 1.02 to (40 ht.) at the pule. (3) Lightning Conductors. Where practicable, a separa- tion of at least 1.8 m (6 ft) shall be maintained between any (C) On Masts. Aerial coaxial cables shall be permitted to coaxial cable and lightning conductors. be attached to an above-the-roof raceway mast that does FPN: For additional information regarding overhead wires not enclose or support conductors of electric light or power and cables, see ANSI C2-2007, National Electric Safety circuits. Code, Part 2, Safety Rules for Overhead Lines. (D) Above Roofs. Coaxial cables shall have a vertical 820.47 Underground Circuits Entering Buildings. Un- clearance of not less than 2.5 m (8 ft) from all points of derground coaxial cables entering buildings shall comply roofs above which they pass. with 820.47(A) and (B). Exception No. 1: Auxiliary buildings such as garages and (A) Underground Systems with Electric Light and the like. Power Conductors. Underground coaxial cables in a duct, pedestal, handhole enclosure, or manhole that contains Exception No. 2: A reduction in clearance above only the electric light or power conductors or Class 1 circuits shall overhanging portion of the roof to not less than 450 mot be in a section permanently separated from such conductors (18 in.)shrill be permitted if(1) not more than 1.2 in (4 ft) by means of a suitable barrier. of communications service drop conductors pass above the roof overhang, and (2) they are terminated at a raceway (B) Direct-Buried Cables and Raceways. Direct-buried mast or other approved support. coaxial cable shall be separated at Ieast 300 mm (12 in.) Exception No. 3: Where the roof has a slope of not less from conductors of any light or power or Class I circuit. than 100 tint in 300 inn (4 in. in 12 in.), a reduction in Exception No. 1: Where electric service conductors or co- clearance to not less than 900 min (3 ft)shall be permitted. axial cables are installed in raceways or have metal cable armor. (E) Between Buildings.Coaxial cables extending between Exception No. 2: Where electric light or power branch- buildings and also the supports or attachment fixtures shall circuit or feeder conductors or Class I circuit conductors be acceptable for the purpose and shall have sufficient are installed in u raceway or in metal-sheathed, metal-clad, strength to withstand the loads to which they may be sub- jected. Type OF or Type USE cables; or the coaxial cables have jected. metal cable armor or are installed in a raceway. Exception: Where a coaxial cable does not have sufficient strength to be self-supporting, it shall be attached to a 820.48 Unlisted Cables Entering Buildings. Unlisted supporting messenger cable that, together with the attach- outside plant coaxial cables shall be permitted to be in- ment fixtures or.supports, .shall be acceptable for the pur- stalled in locations as described in 820.154(D), where the pose and shall have sufficient .strength to withstand the length of the cable within the building, measured from its loads to which they may be ,subjected. point of entrance, does not exceed 15 m (50 ft) and the cable enters the building from the outside and is terminated (F) On Buildings. Where attached to buildings, coaxial at a grounding block. cables shall be securely fastened in such a manner that they will be separated from other conductors in accordance with III. Protection 820.44(F)(1), (F)(2), and (17)(3). 820.93 Grounding of the Outer Conductive Shield of (1) Electric Light or Power. The coaxial cable shalt have Coaxial Cables. Coaxial cables entering buildings or at- a separation of at least 100 mm (4 in.) from electric light, tached to buildings shall comply with 820.93(A) or (B). power, Class 1, or non-power-limited fire alarm circuit Where the outer conductive shield of a coaxial cable is conductors not in raceway or cable, or shall be permanently grounded,no other protective devices shall be required.For separated from conductors of the other system by a con- purposes of this section, grounding located at mobile home tinuous and firmly fixed nonconductor in addition to the service equipment located within 9.0 m (30 ft) of the exte- insulation on the wires. rior wall of the mobile home it serves, or at a mobile home 2008 Edition NATIONAL ELECTRICAL CODE 70-655 820.100 ARTICLE 820—COMMUNITY ANTENNA"TELEVISION AND RADIO DISTRIBUTION SYSTEMS disconnecting means grounded in accordance with 250.32 FPN: Similar grounding conductor length limitations ap- and located within 9.0 m (30 ft) of the exterior wall of the plied at apartment buildings and commercial buildings will mobile home it serves, shall be considered to meet the help to reduce voltages that may be developed between the building's power and communications systems during requirements of this section. lightning events. FPN: Selecting a grounding location to achieve the short- Exception: In one-and two-family dwellings where it is not est practicable grounding conductor helps limit potential practicable to achieve an overall maximum grounding con- differences between CATV and other metallic systems. ductor length of 6.0 in (20 ft), u separate grounding elec- (A) Entering Buildings.In installations where the coaxial trade as specified in 250.52(A)(5), (A)(6), or(A)(7)shall be cable enters the building, the outer conductive shield shall used, the grounding conductor .shall be connected to the be grounded in accordance with 820.100. The grounding separate grounding electrode in accordance with 250.70, shall be as close as practicable to the point of entrance. and the.separate grounding electrode shall be connected to the power grounding electrode system in accordance with (B) Terminating Outside of the Building. In installations 820.100(D). where the coaxial cable is terminated outside of the build- ing,the outer conductive shield shall be grounded in accor- (5) Run in Straight Line. The grounding conductor shall dance with 820.100. The grounding shall be as close as be run to the grounding electrode in as straight a line as practicable to the point of attachment or termination. practicable. (C) Location. Where installed, a listed primary protector (6) Physical Protection. The grounding conductor shall be shall be applied on each community antenna and radio dis- protected where exposed to physical damage. Where the tribution (CATV) cable external to the premises.The listed grounding conductor is run in a metal raceway, both ends primary protector shall be located as close as practicable to of the raceway shall be bonded to the grounding conductor the entrance point of the cable on either side or integral to or the same terminal or electrode to which the grounding the ground block. conductor is connected. (D) Hazardous (Classified) Locations. Where a primary (B) Electrode. The grounding conductor shall be con- protector or equipment providing the primary protection nected in accordance with 8 20.100(13)(1), (13)(2), or(13)(3). function is used, it shall not be located in any hazardous (1) In Buildings or Structures with an Intersystem (classified)location as defined in 500.5 or in the vicinity of Bonding Termination.If the building or structure served has easily ignitible material. an intersystem bonding termination, the grounding conductor Exception: As permitted in 501.150, 502.150, and 503.150. shall be connected to the intersystem banding termination. (2) in Buildings or Structures with Grounding Means. IV. Grounding Methods If the building or structure served has no intersystem bond- ing termination, the grounding conductor shall be con- 820.100 Cable Grounding.The shield of the coaxial cable nected to the nearest accessible location on the following: shall be grounded as specified in 820.100(A) through (D). (t) The building or structure grounding electrode system (A) Grounding Conductor. as covered in 250.50 (2) The grounded interior metal water piping system, (1) Insulation.The grounding conductor shall be insulated within 1.52 m (5 ft) from its point of entrance to the and shall be listed. building, as covered in 250.52 (2) Material. The grounding conductor shall be copper or (3) The power service accessible means external to enclo- other corrosion-resistant conductive material, stranded or sures as covered in 25094 solid. (4) The metallic power service raceway (3) Size. The grounding conductor shall not be smaller (5) The service equipment enclosure than 14 AWG. It shall have a current-carrying capacity (6) The grounding electrode conductor or the grounding approximately equal to that of the outer conductor of the electrode conductor metal enclosure, or coaxial cable. The grounding conductor shall not be re- (7) The grounding conductor or the grounding electrode of quired to exceed 6 AWG. a building or structure disconnecting means that is con- (4) Length. The grounding conductor shall be as short as nected to an electrode as covered in 250.32 practicable, In one- and two-family dwellings, the ground- A bonding device intended to provide a termination ing conductor shall be as short as practicable, not to exceed point for the grounding conductor (intersystem bonding) 6.0 m (20 ft) in length. shall not interfere with the opening of an equipment enclo- 70-656 NATIONAL ELECTRICAL CODL 2008 Edition ARTICLE 820—COMMUNITY ANTENNA TELEVISION AND RADIO DISTRIBUTION SYSTEMS 820.133 sure.A bonding device shall be mounted on non-removable surge arrester ground, shall be connected to a grounding parts. A bonding device shall not be mounted on a door or conductor in accordance with$20.100(B)(2), cover even if the door or cover is non-removable. (2) Where there is no mobile home disconnecting means For purposes of this section, the mobile home service grounded in accordance with 250.32 and located within equipment or the mobile home disconnecting means, as 9.0 m (30 ft) of the exterior wall of the mobile home it described in 820.93, shall be considered accessible. serves, the coaxial cable shield ground, or surge ar- (3) In Buildings or Structures Without Intersystem rester ground, shall be connected to a grounding con- Bonding Termination or Grounding Means. If the build- ductor in accordance with 820.100(13)(2). ing or structure served has no intersystem bonding termi- (B) Bonding.The coaxial cable shield grounding terminal, nation or grounding means, as described in 820.100(B)(2), surge arrester grounding terminal, or grounding electrode the grounding conductor shall be connected to either of the shall be connected to the metal frame or available ground- following: ing terminal of the mobile home with a copper grounding (1) To any one of the individual electrodes described in conductor not smaller than 12 AWG under any of the fol- 250.52(A)(1), (A)(2), (A)(3), (A)(4); or, lowing conditions: (2) If the building or structure served has no intersystem (1) Where there is no mobile home service equipment or bonding termination or grounding means, as described disconnecting means as in 820.106(A) in 820.100(B)(2) or (13)(3)(1), to any one of the indi- (2) Where the mobile home is supplied by cord and plug vidual electrodes described in 250.52(A)(5), (A)(7), and (A)(8). V. Installation Methods Within Buildings (C) Electrode Connection. Connections to grounding electrodes shall comply with 250.70. 820.110 Raceways for Coaxial Cables. Where coaxial cables are installed in a raceway, the raceway shall be ei- (D) Bonding of Electrodes.A bonding jumper not smaller ther of a type permitted in Chapter 3 and installed in accor- than 6 AWG copper or equivalent shall be connected be- dance with Chapter 3 or listed plenum CATV raceway, tween the community antenna television system's ground- listed riser CATV raceway,or listed general-purpose CATV ing electrode and the power grounding electrode system at raceway installed in accordance with 820.154, and with the building or structure served where separate electrodes 362.24 through 362.56, where the requirements applicable are used. to electrical nonmetallic tubing apply. Exception: At mobile homes as covered in 520.106. Exception: Conduit fill restrictions shall not apply: FPN No. l: See 250.60 for use of air terminals (lightning 820.113 Installation of Coaxial Cables. Coaxial cables rods). installed in buildings shall be listed. FPN No. 2: Bonding together of all separate electrodes Exception: Coaxial Cables that comply with 800.48 shall limits potential differences between them and between their P y' associated wirin g systems.s stems. not be required to be listed. (E) Shield Protection Devices. Grounding of a coaxial 820.I33 Installation of Coaxial Cables and Equipment. drop cable shield by means of a protective device that does Beyond the point of grounding, as defined in 820.93, the not interrupt the grounding system within the premises coaxial cable installation shall comply with 820.133(A) shall be permitted, and (8). 820.103 Equipment Grounding. Unpowered equipment (A) Separation from Other Conductors. and enclosures or equipment powered by the coaxial cable (1) In Raceways, Cable Trays, and Boxes. shall be considered grounded where connected to the me- tallic cable shield. (a) Other Circuits. Coaxial cables shall be permitted in the same raceway, cable tray, or enclosure with jacketed 820.106 Grounding and Bonding at Mobile Homes. cables of any of the following: (1) Class 2 and Class 3 remote-control, signaling, and (A) Grounding. Grounding shall comply with 820.106(A) power-limited circuits in compliance with Article 725 (1) and (A)(2). (2) Power-limited fire alarm systems in compliance with (1) Where there is no mobile home service equipment lo- Article 760 cated within 9.0 m (30 ft) of the exterior wall of the (3) Nonconductive and conductive optical fiber cables in mobile home it serves,the coaxial cable shield ground,or compliance with Article 770 2008 Edition NATIONAL ELECTRICAL CODE 70-657 820.154 ARTICLE 820—COMMUNITY ANTENNA TELEVISION AND RADIO DISTRIBUTION SYSTEMS (4) Communications circuits in compliance with Article 800 820.154 Applications of Listed CATV Cables and (5) Low-power network-powered broadband communica- CATV Raceways. CATV cables shall comply with the re- tions circuits in compliance with Article 830 quirements of 820.154(A) through (E) or where cable sub- (b) Electric Light, Power, Class 1, Non—Power-Limited stitutions are made as shown in Table 820.154(E). Fire Alarm, and Medium-Power Network-Powered Broad- (A) Plenums. Coaxial cables installed in ducts, plenums, band Communications Circuits. Coaxial cable shall not be and other spaces used for environmental air shall be Type placed in any raceway, compartment, outlet box, junction CATVP. Abandoned cables shall not be permitted to re- box, or other enclosures with conductors of electric light, main. Types CATVP, CATVR, CATV, and CATVX cables power, Class I, non—power-limited Eire alarm, or medium- installed in compliance with 300.22 shall be permitted, power network-powered broadband communications Listed plenum CATV raceways shall be permitted to be circuits. installed in ducts and plenums as described in 300.22(B) Exception No. 1: Where all of the conductors of electric and in other spaces used for environmental air as described light, power Class 1, non—power-limited fire alarm, and in 300.22(C). Only Type CATVP cable shall be permitted medium-power network-powered broadband communica- to be installed in these raceways. tions circuits are separated from all of the coaxial cables by (B) Riser.Coaxial cables installed in risers shall comply with a permanent barrier or listed divider. any of the requirements of 820.154(B)(1) through (B)(3). Exception No. 2: Power circuit conductors in outlet boxes, junction boxes, or similar fittings or compartments where (1) Coaxial Cables in Vertical Runs. Coaxial cables in- such conductors are introduced solely for power supply to stalled in vertical runs and penetrating more than one floor, the coaxial cable system distribution equipment. The power or cables installed in vertical runs in a shaft, shall be Type circuit conductors shall be routed within the enclosure to CATVR. Floor penetrations requiring Type CATVR shall maintain a fninimum 6-nun (0.25-in.) .separation from co- contain only cables suitable for riser or plenum use. Listed axial cables. riser CATV raceways and listed plenum CATV raceways shall be permitted to be installed in vertical riser runs in a (2) Other Applications. Coaxial cable shall be separated shaft from floor to floor. Only Type CATVR and CATVP at least 50 mm (2 in.) from conductors of any electric cables shall be permitted to be installed in these raceways. light, power, Class 1, non—power-limited fire alarm, or medium-power network-powered broadband communi- (2) Metal Raceways or Fireproof Shafts. Types CATV and CATVR cables shall be permitted to be encased in a cations circuits. metal raceway or located in a fireproof shaft having fire- Exception No. 1: Where either (1) all of the conductors of stops at each floor, electric light,power, Class 1, non power-limited fire alarm, and medium-power network-powered broadband communi- (3) One- and Two-Family Dwellings. Types CATV and cations circuits are in a raceway, or in metal-sheathed, CATVX cables shall be permitted in one- and two-family metal-clad, nonmetallic-sheathed, Type AC or Type OF dwellings, cables, or (2) all of the coaxial cables are encased in FPN: See 820.3(A) for the firestap requirements for Roar raceway: penetrations. Exception No. 2: Where the coaxial cables are perma- ne�rth• separated from the conductors of electric light, (C) Other Wiring Within Buildings. Cables installed in power, Class 1, non—power-limited fire alarm, and medium- building locations ocher than the locations covered in 820.154(A) and (B) shall be in accordance with any of the power network-powered broadband communications cir- cuits by a continuous cirri firmly fixed nonconductor, such requirements in 820.154(C)(1) through (C)(5). as porcelain tubes or flexible tubing, in addition to the (1) General.Type CATV shall be permitted. Listed CATV insulation on the wire. general-purpose raceways,listed riser CATV raceways,and (B) Support of Cables. Raceways shall be used for their listed plenum CATV raceways shall be permitted. Only Types CATV, CATVX, CATVR, or CATVP cables shall be intended purpose. Coaxial cables shall not be strapped, permitted to be installed in these CATV raceways. taped, or attached by any means to the exterior of any conduit or raceway as a means of support. (2) In Raceways. Type CATVX shall be permitted to be Exception: Overhead(aerial) spans of coaxial cables shall installed in a raceway. be permitted to be attached to the exterior of a raceway- (3) Nonconcealed Spaces. Type CATVX shall be permit- type mast intended for the attachment and support of such ted to be installed in nonconcealed spaces where the ex- cables, posed length of cable does not exceed 3 m (10 ft). 70-658 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 820—COMMUNITY ANTENNA TELEVISION AND RADIO DISTRIBUTION SYSTEMS 820.179 (4) One- and Two-Family Dwellings. Type CATVX Vi. Listing Requirements cables less than 10 mm (0.375 in.) in diameter shall be 820.179 Coaxial Cables. Cables shall be listed in accor- permitted to be installed in one- and two-family dwellings. dance with 820.179(A) through (D) and marked in accor- (5) Multifamily Dwellings. Type CATVX cables less than dance with Table 820.179. The cable voltage rating shall 10 mm (0.375 in.) in diameter shall be permitted to be not be marked on the cable. installed in multifamily dwellings. FPN: Voltage markings on cables could be misinterpreted (D) Cable Trays. Cables installed in cable trays shall be to suggest that the cables may be suitable for Class 1, CATVR, and CATV: Types CATVP, electric light, and power applications. Exception: Voltage markings shall be permitted where the (E) Cable Substitutions. The uses and substitutions for cable has multiple listings and voltage marking is required CATV coaxial cables listed in Table 820.154(E) and iglus- for one or more of the listings, trated in Figure 820.154(E) shall be permitted. FPN: The substitute cables in Table 820.154(E)and Figure (A) Type CATVP.Type CATVP community antenna tele- 820.154(E)are only coaxial-type cables, vision plenum coaxial cables shall be listed as being suit- able for use in ducts, plenums, and other spaces used for Table 820.154(E) Coaxial Cable Uses and Permitted environmental air and shall also be listed as having adequate Substitutions Fire-resistant and low smoke-producing characteristics. FPN: One method of defining a cable that is low smoke- producing cable and tire-resistant cable is that the cable CATVP CMP, BLP exhibits a maximum peak optical density of 0.5 or less,an average optical density of 0.15 or less, and a maximum CATVR CATVP, CMP. CMR, Name spread distance of 1.52 m(5 ft)or less when tested in BMR, BLP, BLR accordance with NFPA 262, Standard Method of Test for Flange Travel and Smoke of Wires and Cables for Use in CATV CATVP, CMP, Air Handling Spaces. CATVR, CMR, CMG, CM, (B) Type CATVR.Type CATVR community antenna tele- BIvlR, BM, BLP, BLR, BL vision riser coaxial cables shall be listed as being suitable CATVX CATVP, CMP, for use in a vertical run in a shaft or from floor to floor and CATVR, CMR, shall also be listed as having fire-resistant characteristics ca- CATV, CMG, CM, pable of preventing the carrying of fire from floor to floor. BMR, BM, BLP- BLR, BL, BLX FPN: One method of defining fire-resistant characteristics capable of preventing the carrying of fire from floor to floor is that the cables pass the requirements of ANSWUL 1666- 2002,Standard Test for Flanne Propagation Height of Elec- Plenum GMP CATVP BLP trical and Optical-Fiber Cable Installed Vertically in Shafts. BMR (C) Type CATV. Type CATV community antenna televi- Riser CMR CATVR BLP BLR sion coaxial cables shall be listed as being suitable for -------------------------CATV----- -------------- general-purpose CATV use, with the exception of risers and plenums, and shall also be listed as being resistant to the General CMG BMR,BM spread of fire. purpose CM BLP,BLR.BL p -------------------------- --------------------------------- -- FPN: One method of defining resistant to the spread of fire is that the cables do not spread fire to the top of the tray in BMR,BM the "UL.Flame Exposure,Vertical Tray Flame Test"in UL Dwellings CMD_ CATVX BLP,BLR,BL,BLX 1585-2000, .Standard for Safety for Vertical-Tray Fire- Propagation and Smoke-Release Test for Electrical and A B Coaxial cable A shall be permitted to be used in Optical-Fiber Cables.The smoke measurements in the test place of coaxial cable B. method are not applicable. Type BL—Network-powered broadband communications low- Another method of defining resistant to the spread of fire power cable is for the damage(char length)not to exceed 1.5 m(4 ft 1 I in.) Type BM—Network-powered broadband communications medium- when performing the CSA"Vertical Flame Test—Cables in power cable Cable Trays," as described in GSA C22.2 No. 0.3-M-2001, Type CATV—Community antenna television cables Test Methods for Electrical Wires and Cables. Type CM—Communications cables (D) Type CATVX. Type CATVX limited-use community Figure 820.154(E) Cable Substitution Hierarchy. antenna television coaxial cables shall be listed as being 2008 Edition NATIONAL ELECTRICAL CODE 70-659 820.182 ARTICLE 830—NETWORK-POWERED BROADBAND COMMUNICATIONS SYSTEMS suitable for use in dwellings and for use in raceway and shall also be listed as being resistant to flame spread. ARTICLE 830 FPN: One method of determining that cable is resistant to Network-Powered Broadband flame spread is by testing the cable to the VW-1 (vertical- Communications Systems wire) flame test in ANSIIUL 1581-2001, Reference Stan- dard for Electrical Wires, Cables and Flexible Cords. Table 820.179 Coaxial Cable Markings I. General 830.1 Scope. This article covers network-powered broad- Cable band communications systems that provide any combina- Marking Type Reference tion of voice, audio, video, data, and interactive services CATVP CATV plenum cable 820.179(A) and through a network interface unit. 820.154(A) FPN No. 1: Atypical basic system configuration includes a CATVR CATV riser cable 820.179(B) and cable supplying power and broadband signal to a network 820.154(B) interface unit that converts the broadband signal to the CATV CATV cable 820.179(0) and component signals. Typical cables are coaxial cable with 820.154(D) both broadband signal and power on the center conductor, CATVX CATV cable, limited use 820.179(D) and composite metallic cable with a coaxial member for the 820.154(D) broadband signal and a twisted pair for power, and com- posite optical fiber cable with a pair of conductors for FPN No. 1: Cable types are listed in descending order of power. Larger systems may also include network compo- fire-resistance rating. nents such as amplifiers that require network power. FPN No. 2: See the referenced sections for listing require- FPN No. 2: See 90.2(B)(4) for installations of broadband ments and permitted uses. communications systems that are not covered. 820.182 CATV Raceways. CATV raceways shall be listed 830.2 Definitions. See Article 100. For purposes of this in accordance with 820.182(A) through (C). article, the following additional definitions apply. (A) Plenum CATV Raceways. Plenum CATV raceways Abandoned Network-Powered Broadband Communica- shall be listed for use in other spaces used for environmen- tions Cable. Installed network-powered broadband com- tal air and shall also be listed as having adequate fire- munications cable that is not terminated at equipment other resistant and low smoke-producing characteristics. than a connector and not identified for future use with a tag. FPN: One method of defining that an optical fiber raceway FPN: See Article 100 for a definition of Equipment. is a low smoke-producing raceway and a fire-resistant race- way is that the raceway exhibits a maximum peak optical Block. A square or portion of a city, town, or village en- density of 0.5 or less, an average optical density of 0.15 or closed by streets, including the alleys so enclosed but not less,and a maximum flame spread distance of 1.52 m(5 ft) any street. or less when tested in accordance with the plenum test in UL 2024, Standard for Optical-Fiber Cable Raceway. Exposed (to Accidental Contact). A circuit in such a po- sition that, in case of failure of supports or insulation, con- (B) Riser CATV Raceways. Riser CATV raceways shall tact with another circuit may result. be listed for use in risers and shall also be listed as having adequate fire-resistant characteristics capable of preventing FPN: See Article 100 for two other definitions of Exposed. the carrying of fire from floor to floor. Fault Protection Device. An electronic device that is in- FPN: One method of defining fire-resistant characteristics tended for the protection of personnel and functions under capable of preventing the carrying of fire from floor to floor fault conditions, such as network-powered broadband corn- is that the raceways pass the requirements of the Test for munications cable short or open circuit, to limit the current Flame Propagation (Riser) in UL 2024, Standard far p Optical-Fiber Cable Raceway. or voltage, or both, for a low-power network-powered broadband communications circuit and provide acceptable (C) General-Purpose CATV Raceways. General-purpose protection from electric shock. CATV raceways shall be listed suitable for general-purpose use and shall also be listed as being resistant to the spread Network Interface Unit (NIU). A device that converts a of fire. broadband signal into component voice, audio, video, data, and interactive services signals.The NIU provides isolation FPN: One method of defining resistance to the spread of fire is that the raceway passes the requirements of the between the network power and the premises signal cir- Vertical-Tray Flame Test (General Use) in UL 2024, Stan- cuits. The NIU may also contain primary and secondary dard for Optical-Fiber Cable Raceway. protectors. 70-660 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 830—NETWORK-POWERED BROADBAND COMMUNICATIONS SYSTEMS 830.24 Network-Powered Broadband Communications Circuit. current to ground limited to 10 MA dc, that meet the The circuit extending from the communications utility's current and power limitation for medium-power serving terminal or tap up to and including the NIU. sources in Table 830.15 shall be classified as medium- FPN: Atypical single-family network-powered communi- power sources. cations circuit consists of a communications drop or com- FPN: one way t0 determine compliance with 830.15(2)is munications service cable and an NIU and includes the listed information technology equipment intended to Supply cornmunications utility's serving terminal or tap where it is power via a telecommunication network that complies with not under the exclusive control of the communications the requirements for RFT V circuits as defined in UL utility. 60950-21, Standard for Safety for Information Technology 2l:Remote Power Feeding. Point of Entrance. The paint within a building at which Equipment—Safety—Part the cable emerges from an external wall, from a concrete 'liable 830.15 Limitations for Network-Powered Broadband floor slab, or from a rigid metal conduit(Type RMC) or an Communications Systems intermediate metal conduit (Type IMC) connected by a grounding conductor to an electrode in accordance with Network Power Source Low Medium 830.100(B). Circuit voltage, V,n,,,, (volts)' 0-100 0-150 Power 250 250 830.3 Other Articles. Circuits and equipment shall com- limitation,VA.,,,(volt-amperes)' ply with 830.3(A) through (D). Current limitation, 1,,,,,x 1000/vM_ 10001v_a, (A) Hazardous (Classified) Locations. Network-powered (amperes)' broadband communications circuits and equipment in- Maximum power rating 100 100 stalled in a location that is classified in accordance with (volt-amperes) 500.5 shall comply with the applicable requirements of Maximum voltage rating 100 150 (volts) Chapter 5. Maximum overcurrent 1001V m.,x NA (B) Ducts, Plenums, and Other Air-Handling Spaces. protection (amperes)' Section 300.22 shall apply where installed in ducts, ple- 'V„tav I„„x, and VA,,,„ are determined with the current-limiting im- nums, or other spaces used for environmental air. pedance in the circuit (not bypassed) as follows: V,,,,,—Maximum system voltage regardless of load with rated in- Exception: As permitted in 830.154(A). put applied. ].,,—Maximum system current under any noncapacitive load. in- (C) Equipment in Other Space Used for Environmental cluding short circuit, and with overcurrent protection bypassed if used. I., limits apply after I minute of operation. Air. Section 300.22{C) shall apply. VAmax Maximum volt-ampere output after 1 minute of operation regardless of load and overcurrent protection bypassed if used. (D) Output Circuits. As appropriate for the services 'Overcurrent protection is not required where the current-limiting de- provided, the output circuits derived from the network vice provides equivalent current limitation and the current-limiting interface unit shall comply with the requirements of the device does not reset until power or the load is removed. following: (1) Installations of communications circuits--Article 800 830.21 Access to Electrical Equipment Behind Panels Designed to Allow Access. Access to electrical equipment (2) Installations of community antenna television and radio shall not be denied by an accumulation of network-powered distribution circuits —Article 820 broadband communications cables that prevents removal of Exception: 830.90(B)(3) shall apphy where protection is panels, including suspended ceiling panels. provided in the output of the NIU. 830.24 Mechanical Execution of Work. Network-pow- (3) Installations of optical fiber cables —Article 770 ered broadband communications circuits and equipment (4) Installations of Class 2 and Class 3 circuits—Article 725 shall be installed in a neat and workmanlike manner.Cables (5) Installations of power-limited fire alarm circuits —Ar- installed exposed on the surface of ceilings and sidewalls ticle 760 shall be supported by the building structure in such a man- ner that the cable will not be damaged by normal building 830.15 Power Limitations. Network-powered broadband use. Such cables shall be secured by hardware including communications systems shall be classified as having low- straps, staples, cable ties, hangers, or similar fittings de- or medium-power sources as Specified in 830.15(l) or (2). signed and installed so as not to damage the cable. The (I) Sources shall be classified as defined in Table 830.15. installation shall also conform to 300.4(D) and 300.11. (2) Direct-current power Sources exceeding 150 volts to FPN: Accepted industry practices are described in ground,but no move than 200 volts to ground, with the ANSUNECAIBICSI 568-2006, Standard for Installing 2008 Edition NATIONAL ELECTRICAL CODE 70-661 830.25 ARTICLE 830—NETWORK-POWERED BROADBAND COMMUNICATIONS SYSTEMS Commercial Building Telecommunications Cablilkq; ANSI/ 820, shall be permitted for low-power-type, network- TIA/EIA-568-B.1-2004 — Part I General Requirements powered broadband communications circuits. Commercial Building Telecommunications Cabling Standard; ANSI/FIA-569-B-2004—Commercial Building Standard for Telecommunications Pathways and Spaces;ANSIMA-570-B 830.44 Aerial Cables. Aerial network-powered broadband --Residential Telecommunications Infrastructure; and other communications cables shall comply with 830.44(A) ANSI-approved installation standards. through (I). 830.25 Abandoned Cables. The accessible portion of FPN: For additional information regarding overhead wires and cables, see ANSI C2-2007, National Electric Safety abandoned network-powered broadband cables shall be re- Code, Part 2, Safety Rules For Overhead Lines. moved. Where cables are identified for future use with a tag, the tag shall be of sufficient durability to withstand the (A) On Poles.Where practicable• network-powered broad- environment involved. band communications cables on poles shall be located be- low the electric light,power, Class 1, or non-power-limited 830.26 Spread of Fire or Products of Combustion. In- fire alarm circuit conductors and shall not be attached to a stallations of network-powered broadband cables in hollow crossarm that carries electric light or power conductors, spaces,vertical shafts,and ventilation or air-handling ducts shall be made so that the possible spread of fire or products {B) Climbing Space. The climbing space through of combustion will not be substantially increased.Openings network-powered broadband communications cables shall around penetrations of network-powered broadband cables comply with the requirements of 225.14(D). through fire-resistant-rated walls, partitions, floors, or ceil- (C) Lead-in Clearance. Lead-in or aerial-drop network- ings shall be firestopped using approved methods to main- powered broadband communications cables from a pole or tain the fire resistance rating. other support, including the point of initial attachment to a FPN: Directories of electrical construction materials pub- building or structure,shall be kept away from electric light, lished by qualified testing laboratories contain many listing power, Class 1, or non-power-limited fire alarm circuit con- installation restrictions necessary to maintain the fire- ductors so as to avoid the possibility of accidental contact. resistive rating of assemblies where penetrations or open- ings are made. Building codes also contain restrictions on Exception: Where proximity to electric light, power. Class membrane penetrations on opposite sides of a fire 1, or non-power-limited fire alarm circuit service conduc- resistance-rated wall assembly.An example is the 600-mm tors cannot be avoided, the installation shall be such as to (24-in.)minimum horizontal separation that usually applies provide clearances o not less than 300 mar 12 in.)from between boxes installed on opposite sides of the wall.As- p f ( f sistance in complying with 830.26 can be found in building light, power, Class 1, or non-power-limited fire alarm cir- codes, fire.resistance directories, and product listings. cuit service drops. The clearance requirement shall apph to all points along the drop, and it shall increase to 1.02 in II. Cables Outside and Entering Buildings (40 in.) at the pole. 830.40 Entrance Cables. Network-powered broadband (D) Clearance from Ground.Overhead spans of network- communications cables located outside and entering build- powered broadband communication cables shall conform to ings shall comply with 830.40(A) and (B). not less than the following: (1) 2.9 m (9.5 ft) — above finished grade, sidewalks, or (A) Medium-Power Circuits. Medium-power network- from any platform or projection from which they might powered broadband communications circuits located out- be reached and accessible to pedestrians only side and entering buildings shall be installed using Type (2) 3.5 m(11.5 ft)—over residential property and driveways, BMU, Type BM, or Type BMR network-powered broad- and those commercial areas not subject to truck traffic band communications medium-power cables. (3) 4.7 m (15.5 ft)—over public streets, alleys, roads, park- (B) Low-Power Circuits. Low-power network-powered ing areas subject to truck traffic, driveways on other than broadband communications circuits located outside and en- residential property, and other land traversed by vehicles testng buildings shall be installed using Type BLU or Type such as cultivated, grazing• forest, and orchard BLX low-power network-powered broadband communica- FPN: These clearances have been specifically chosen to tions cables. Cables shown in Table 830.154 shall be per- correlate with ANSI C2-2007, National Electrical Safely Code,Table 232-1,which provides for clearances of wires, mitted to substitute. conductors, and cables above ground and roadways, rather Exception: Outdoor community antenna television and ra- than using the clearances referenced in 225.18. Because Article 800 and Article 820 have had no required clear- dio distribution system coaxial cables installed prior to ances,the communications industry has used the clearances January 1, 2000, and installed in accordance with Article from the NESC for their installed cable plant. 70-662 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 830 NETWORK-POWERED BROADBAND COMMUNICATIONS SYSTEMS 830.47 (E) Over Pools. Clearance of network-powered broadband (1) Electric Light or Power.The network-powered broad- communications cable in any direction from the water band communications cable shall have a separation of at level, edge of pool, base of diving platform, or anchored least 100 mm (4 in.) from electric light, power, Class 1, or raft shall comply with those clearances in 680.8. non--power-limited fire alarm circuit conductors not in race- way or cable, or be permanently separated from conductors (F) Above Roofs. Network-powered broadband communi- of the other system by a continuous and firmly fixed non- cations cables shall have a vertical clearance of not less than conductor in addition to the insulation on the wires. 2.5 m (8 ft) from all points of roofs above which they pass. Exception No. 1: Auxiliary buildings such as garages and (2) Other Communications Systems. Network-powered the like. broadband communications cables shall be installed so that there will be no unnecessary interference in the mainte- E.rc•eption No. 2: A reduction in clearance above only the nance of the separate systems. In no case shall the conduc- overhanging portion of the roof to not less than 450 mm tors, cables, messenger strand, or equipment of one system (18 in.) shall be permitted if(1) not more than 1.2 ni (4 ft) cause abrasion to the conductors, cables, messenger strand, of the broadband communications drop cables pass above or equipment of any other system. the roof overhang, and (2) they are terminated at a through-the-roof raceway or support. (3) Lightning Conductors. Where practicable, a separa- Exception No. 3: Where the roof has a slope of not less tion of at least 1.8 in (6 ft)shall be maintained between any than 100 nun in 300 mm (4 in. in 12 in.), a reduction in network-powered broadband communications cable and clearance to not less than 900 min (3 ft)shall be permitted. lightning conductors. (G) Final Spans. Final spans of network-powered broad- (4) Protection from Damage. Network-powered broad- band communications cables without an outer jacket shall band communications cables attached to buildings and lo- be permitted to be attached to the building, but they shall be cited within 2.5 m(8 ft) of finished grade shall be protected kept not less than 900 mm (3 ft) from windows that are by enclosures, raceways, or other approved means. designed to be opened, doors, porches, balconies, ladders, Exception: A lose-power network-powered broadband stairs, lire escapes, or similar locations. communications circuit that is equipped with a listed fault Exception: Conductors run above the top level of a win- protection device, appropriate to the network powered dow shall be pennitted to be less than the 900-nun (3 ft) broadband communications cable used, and located on the requirement above. network side of the network-powered broadband communi- Overhead network-powered broadband communica- cations cable being protected. tions cables shall not be installed beneath openings through 830.47 Underground Circuits Entering Buildings. Un- which materials may be moved, such as openings in farm derground network-powered broadband communications and commercial buildings, and shall not be installed where they will obstruct entrance to these building openings. cables entering buildings shall comply with 830.47(A) through (D). (H) Between Buildings. Network-powered broadband communications cables extending between buildings and (A) Underground Systems with Electric Light and also the supports or attachment fixtures shall be acceptable Power Conductors. Underground network-powered broad- for the purpose and shall have sufficient strength to with- band communications cables in a duct, pedestal, handhole stand the loads to which they may be subjected, enclosure, or manhole that contains electric light, power conductors, non—power-limited fire alarm circuit conduc- Exception: Where a network-powered broadband commu- tors, or Class I circuits shall be in a section permanently nications cable does not have sufficient strength to be .self- separated from such conductors by means of a suitable supporting. it .shall be attached to a supporting messenger barrier. cable that, together with the attachment fixtures or .sup- ports, shall be acceptable for the purpose and shall have (B) Direct-Buried Cables and Raceways. Direct-buried sufficient strength to withstand the loads to which theY mad' network-powered broadband communications cables shall be subjected. be separated by at least 300 mm(12 in.)from conductors of {I) On Buildings. Where attached to buildings, network- any light, power, non—power-limited fire alarm circuit con- ductors or Class I circuit. powered broadband communications cables shall be se- curely fastened in such a manner that they are separated Exception No. 1: Where electric service conductors or from other conductors in accordance with 830.44(l)(l) network-powered broadband communications cables are through (1)(4). installed in raceways or have metal cable armior. 2008 Edition NATIONAL ELECTRICAL CODE 70-663 830.90 ARTICLE 830—NETWORK-POWERED BROADBAND COMMUNICATIONS SYSTEMS Exception No, 2: Where electric light or power branch- protection device, appropriate to the network-powered circuit or feeder conductors, non power-limited fire alarm broadband communications cable used, and located on the circuit conductors, or Class I circuit conductors are in- network side of the ne4vork-powered broadband communi- stalled in a racetvuy� or in metal-sheathed, metal-clad, or cations cable being protected. Type OF or Type USE cables,- or the network-powered broadband communications cables have metal cable armor (D) Pools.Cables located under the pool or within the area or are installed in a raceway. extending 1.5 m (5 ft) horizontally from the inside wall of the pool shall meet those clearances and requirements (C) Mechanical Protection. Direct-buried cable, conduit, specified in 680.10. or other raceways shall be installed to meet the minimum cover requirements of Table 830.47. In addition, direct- III. Protection buried cables emerging from the ground shall be protected by enclosures, raceways, or other approved means extend- 830.90 Primary Electrical Protection. ing from the minimum cover distance required by Table 830.47 below grade to a point at least 2.5 m (8 ft) above (A) Application. Primary electrical protection shall be finished grade. In no case shall the protection be required to provided on all network-powered broadband communica- exceed 450 mm {18 in.) below finished grade. Type BMU lions conductors that are neither grounded nor interrupted and are run partly or entirely in aerial cable not confined and BLU direct-buried cables emerging from the ground shall within a block. Also, primary electrical protection shall be be installed in rigid metal conduit, intermediate metal conduit, rigid nonmetallic conduit, or other approved means extending Provided on all aerial or underground network-powered From the minimum cover distance required by Table 830.47 broadband communications conductors that are neither grounded nor interrupted and are located within the block below grade to the point of entrance. containing the building served so as to be exposed to light- Exception: A low-power network-poyvered broadband ning or accidental contact with electric light or power con- communications circuit that is equipped with a listed fault ductors operating at over 300 volts to ground, Table 830.47 Network-Powered Broadband Communications Systems Minimum Cover Requirements (Cover is the shortest distance measured between a point on the top surface of any direct-buried cable,conduit,or other raceway and the top surface of finished grade, concrete,or similar cover.) Nonmetallic Raceways Listed for Direct Burial; Rigid Metal Conduit Without Concrete or Intermediate Encasement or Other Location of Direct Burial Cables Metal Conduit Approved Raceways Wiring Method or Circuit mm in. mm in. mm in. All locations not specified below 450 18 150 6 300 12 In trench below 50-mm (2-in.) thick 300 12 150 6 150 6 concrete or equivalent Under a building (in raceway only) 0 0 0 0 0 0 Under minimum of 100-mm (4-in.) thick 300 12 100 4 100 4 concrete exterior slab with no vehicular traffic and the slab extending not less than 150 mm (6 in.) beyond the underground installation One- and two-family dwelling driveways 300 12 300 12 300 12 and outdoor parking areas and used only for dwelling-related purposes (Votes: I. Raceways approved for burial only where concrete encased shall require a concrete envelope not less than 50 mm(2 in.) thick. 2. Lesser depths shall be permitted where cables rise for terminations or splices or where access is otherwise required. 3. Where solid rack is encountered, all wiring shall be installed in metal or nonmetallic raceway permitted for direct burial. The raceways shall be covered by a minimum of 50 mm (2 in.) of concrete extending down to rock. 4. Low-power network-powered broadband communications circuits using directly buried community antenna television and radio distribution system coaxial cables that were installed outside and entering buildings prior to January I, 2000, in accordance with Article 820 shall be permitted where buried to a minimum depth of 300 mm (12 in.). 70-664 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 8311—NETWORK-POWERED BROADBAND COMMUNICATIONS SYSTEMS 830.93 Exception: Where electrical protection is provided oil the A primary protector, whether provided integrally or ex- derived ciwuit(s) (output side of the NIU) in accordance temal to the network interface unit,shall be located as close with 530.90(B)(3). as practicable to the point of entrance. For purposes of this section, a network interface unit FPN No. 1: ors network-powered exposed to lightning broadband com sal con- and any externally provided primary protectors located at lions conductors not exposed to lightning or accidental con- tact with power conductors, providing primary electrical mobile home service equipment located in sight from and protection in accordance with this article helps protect not more than 9.0 m (30 ft) from the exterior wall of the against other hazards, such as ground potential rise caused by mobile home it serves, or at a mobile home disconnecting power fault currents, and above-normal voltages induced by means grounded in accordance with 250.32 and located in fault currents on power circuits in proximity to the network- sight from and not more than 9.0 m(30 ft)from the exterior powered broadband communications conductors. wall of the mobile home it serves, shall be considered to FPN No. 2: Network-powered broadband communications meet the requirements of this section. circuits are considered to have a lightning exposure unless one or more of the following conditions exist: FPN: Selecting a network interface unit and primary pro- (1) Circuits in large metropolitan areas where buildings are Lector location to achieve the shortest practicable primary protector grounding conductor helps limit potential difler- ning.close together and sutliciently high to intercept light ences between communications circuits and other metallic (2) Areas having an average of five or fewer thunderstorm systems. days per year and earth resistivity of less than 100 ohnt-meters. Such areas are found along the Pacific (C) Hazardous {Classified} Locations. The primary pro- coast. tector or equipment providing the primary protection func- tion shall not be located in any hazardous (classified) loca- (1) Fuseless Primary Protectors. Fuseless-type primary tion as defined in 500.5 or in the vicinity of easily ignitible protectors shall be permitted where power fault currents an material. all protected conductors in the cable are safely limited to a Exception:no greater than the current-carrying capacity of the ception: As permitted in 501.150, 502.150, and 503.150. primary protector and of the primary protector grounding 830.93 Grounding or Interruption of Metallic Members conductor. of Network-Powered Broadband Communications (2) Fused Primary Protectors. Where the requirements Cables. Network-powered communications cables entering listed in 830.90(A)(1) are not met, fused-type primary pro- buildings or attaching to buildings shall comply with tectors shall be used. Fused-type primary protectors shall 830.93(A) or (B). consist of an arrester connected between each conductor to For purposes of this section, grounding located at mo- be protected and ground, a fuse in series with each conduc- bile home service equipment located within 9.0 m(30 ft)of for to be protected, and an appropriate mounting arrange- the exterior wall of the mobile home it serves, or at a ment. Fused primary protector terminals shall be marked to mobile home disconnecting means grounded in accordance indicate line, instrument, and ground, as applicable. with 250.32 and located within 9.0 m (30 ft) of the exterior wall of the mobile home it serves, shall be considered to (B) Location.The location of the primary protector, where meet the requirements of this section. required, shall comply with (B)(1), (13)(2), or (13)(3): FPN: Selecting a grounding location to achieve the short- (1) A listed primary protector shall be applied on each est practicable grounding conductor helps limit potential network-powered broadband communications cable ex- differences between the network-powered broadband com- ternal to and on the network side of the network inter- munications circuits and other metallic systems. face unit. (2) The primary protector function shall be an integral part (A) Entering Buildings. In installations where the of and contained in the network interface unit. The network-powered communications cable enters the build- ing, the shield shall be grounded in accordance with network interface unit shall be listed as being suitable g30 100 and metallic members of the cable not used for for application with network-powered broadband com- communications or powering shat] be grounded in accor- munications systems and shall have an external mark- dance with 830.100, or interrupted by an insulating joint or ing indicating that it contains primary electrical protec- equivalent with device.The lion. q grounding or interruption shall be as (3) The primary protector(s) shall be provided on the de- close as practicable to the point of entrance. rived circuit(s) (output side of the NIU), and the com- (B) Terminating Outside of the Building. In installations bination of the NIU and the protector(s) shall be listed where the network-powered communications cable is termi- as being suitable for application with network-powered nated outside of the building, the shield shall be grounded in broadband communications systems. accordance with 830.100, and metallic members of the cable 2008 Edition NATIONAL.ELECTRICAL CODE 70-665 830.100 ARTICLE 830—NETWORK-POWERED BROADBAND COMMUNICATIONS SYSTEMS not used for communications or powering shall be (6) Physical Protection,The grounding conductor Shall be grounded in accordance with 830.100 or interrupted by protected where exposed to physical damage. Where the an insulating joint or equivalent device. The grounding grounding conductor is run in a metal raceway, both ends or interruption shall be as close as practicable to the of the raceway shall be bonded to the grounding conductor point of attachment of the NIU. or the same terminal or electrode to which the grounding FPN: See 830.2 for the definition of Point of Entrance. conductor is connected. (B) Electrode. The grounding conductor shall be con- IV. Grounding Methods nected in accordance with 830.100($)(1), (B)(2),or(13)(3). 830.100 Cable, Network Interface Unit, and Primary (x) In Buildings or Structures with an ]Intersystem Protector Grounding. Network interface units containing Bonding Termination. If the building or structure served protectors, NIUs with metallic enclosures, primary protec- has an intersystem bonding termination, the grounding tors, and the metallic members of the network-powered conductor shall be connected to the intersystem bonding broadband communications cable that are intended to be termination. grounded shall be grounded as specified in 830.100(A) (2) In Buildings or Structures with Grounding Means. through (D). If the building or structure served has no intersystem bond- ing termination, the grounding conductor shall be con- nected to the nearest accessible location on the following: (1) Insulation.The grounding conductor shall be insulated (1) The building or structure grounding electrode system and shall be listed. as covered in 250.50 (2) Material. The grounding conductor shall be copper or (2) The grounded interior metal water piping system, other corrosion-resistant conductive material, stranded or within 1.5 m (5 ft) from its point of entrance to the building, as covered in 250.52 solid. (3) The power service accessible means external to enclo- (3) Size. The grounding conductor shall not be smaller sures as covered in 250.94 than 14 AWG and shall have a current-carrying capacity (4) The metallic power service raceway approximately equal to that of the grounded metallic mem- (5) The service equipment enclosure ber(s) and protected conductor(s) of the network-powered (6) The grounding electrode conductor or the grounding broadband communications cable. The grounding conduc- electrode metal enclosure, or for shall not be required to exceed 6 AWG. (7) The grounding conductor or the grounding electrode of (4) Length. The grounding conductor shall be as short as a building or structure disconnecting means that is practicable. In one-family and multifamily dwellings, the grounded to an electrode as covered in 250.32 grounding conductor shall be as short as permissible, not to A bonding device intended to provide a termination exceed 6.0 m (20 ft) in length. point for the grounding conductor (intersystem bonding) FPN: Similar grounding conductor length limitations ap- shall not interfere with the opening of an equipment enclo- plied at apartment buildings and commercial buildings will sure.A bonding device shall be mounted on non-removable help to reduce voltages that may be developed between the parts. A bonding device shall not be mounted on a door or building's power and communications systems during cover even if the door or cover is non-removable. lightning events. For purposes of this section, the mobile home service Exception: In one-and two-family dwellings where it is not equipment or the mobile home disconnecting means, as practicable to achieve an overall maximum grounding con- described in 83093, shall be considered accessible, ductnr length of 6.0 m (20 ft), a separate communications (3) In Buildings or Structures Without Intersystem ground rod meeting the minimunt dintensional criteria of Bonding Termination or Grounding Means. If the build- 830.100(B)(2)(2) shall be driven, and the grounding con- ing or structure served has no intersystem bonding termi- duc•tor .shall be connected to the communications ground nation or grounding means, as described in 830.100($)(2), rod in accordance with 830.100(C). The communications the grounding conductor shall be connected to either of the ground rod shall be bonded to the power grounding elec- following: trade system in accordance with 830.100(D). (1) To any one of the individual electrodes described in (5) Run in Straight Line. The grounding conductor shall 250.52(A)(1), (A)(2), (A)(3), or (A)(4). be run to the grounding electrode in as straight a line as (2) If the building or structure served has no intersystem practicable. bonding termination or has no grounding means, as 70-666 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 830—NETWORK-POWERED BROADBAND COMMUNICATIONS SYSTEMS 830.133 described in 830.100($)(2) or (13)(3)(1), to any one of protector grounding terminal, or the grounding electrode the individual electrodes described in 250.52(A)(7)and shall be bonded to the metal frame or available grounding (A)(8), or to a ground rod or pipe not less than L5 m terminal of the mobile home with a copper bonding con- (5 ft) in length and 12.7 mm (112 in.) in diameter, ductor not smaller than 12 AWG under any of the following driven, where practicable, into permanently damp earth conditions: and separated from lightning conductors as covered in (1) Where there is no mobile home service equipment or 800.53 and at least 1.8 m (6 ft) from electrodes of other disconnecting means as in 830.106(A) systems. Steam or hot water pipes or lightning-rod con- (2) Where the mobile home is supplied by cord and plug ductors shall not be employed as electrodes for protec- tors, NIUs with integral protection, grounded metallic members, NIUs with metallic enclosures, and other V. Installation Methods Within Buildings equipment. 830.110 Raceways for Low- and Medium-Power Net- (C) Electrode Connection. Connections to grounding work-Powered Broadband Communications Cablm electrodes shall comply with 250.70. Where low- and medium-power network-powered broad- band communications cables are installed in a raceway,the (D) Bonding of Electrodes. A bonding jumper not smaller raceway shall be of a type permitted in Chapter 3 and than 6 AWG copper or equivalent shall be connected be- installed in accordance with Chapter 3. tween the network-powered broadband communications Exception: Conduit fill restrictions shall not apply to low- system grounding electrode and the power grounding elec- trode system at the building or structure served where sepa- Power network powered! broadband communications rate electrodes are used. cables. Exception: At mobile homes as covered in 830.106. 830.133 Installation of Network-Powered Broadband Communications Cables and Equipment. Cable and FPN No. I: See 250.60 for use of air terminals (lightning rods). equipment installations within buildings shall comply with FFN No. 2: Bonding together of all separate electrodes 830.133(A) through (C), as applicable. limits potential differences between them and between their (A) Separation of Conductors. associated wiring systems. (1) In Raceways, Cable'frays, and Enclosures. 830.106 Grounding and Bonding at Mobile Homes. (a) Low-and Medium-Power Network-Powered Broad- (A) Grounding.Grounding Shall comply with 830.106(A)(1) band Communications Circuit Cables. Low- and medium- or(A)(2). power network-powered broadband communications cables (I) Where there is no mobile home service equipment lo- shall be permitted in the same raceway, cable tray, or en- cated within 9.0 m (30 ft) of the exterior wall of the closure. mobile home it serves,the network-powered broadband (b) Law-Power Network-Powered Broadband Commu- communications cable, network interface unit, and psi.- nications Circuit Cables. Low-power network-powered broadband communications cables shall be permitted in the many protector ground shall be installed connected to a grounding conductor in accordance with 830.100(B)(2). same raceway, cable tray, or enclosure with jacketed cables of any of the fallowing circuits: (2) Where there is no mobile home disconnecting means and located grounded in accordance with 250.3'2 (I) Class 2 and Class 3remote-control, signaling, and power-limited circuits in compliance with Article 725 within Sight from, and not more than 9.0 m(30 ft)of, the exterior wall Of the mobile home it serves, the (2) Power-limited fire alarm systems in compliance with network-powered broadband communications cable, Article 760 network interface unit, and primary protector ground (3) Communications circuits in compliance with Article 800 shall be installed connected to a grounding conduc- (4) Nonconductive and conductive optical fiber cables in for in accordance with 830.100(B)(2). compliance with Article 770 (B) Bonding. The network-powered broadband communi- (5) Community antenna television and radio distribution cations cable grounding terminal, network interface unit systems in compliance with Article 820 grounding terminal, if present, and primary protector (c) Medium-Power Network-Powered Broadband Com- grounding terminal shall be bonded together with a copper municatians Circuit Cables. Medium-power network- bonding conductor not smaller than 12 AWG.The network- powered broadband communications cables shall not be powered broadband communications cable grounding ter- permitted in the same raceway,cable tray,or enclosure with minal, network interface unit grounding terminal, primary conductors of any of the following circuits: 2008 Edition NATIONAL ELECTRICAL CODE 70-667 830.151 ARTICLE 8 30—NETWORK,POWERED BROADBAND COMMUNICATIONS SYSTEMS (1) Class 2 and Class 3 remote-control, signaling, and (C) Installation and Use. Section f 10.3(B) shall apply. power-limited circuits in compliance with Article 725 (2) Power-limited fire alarm systems in compliance with 830.151 Medium-Power Network-Powered Broadband Article 760 Communications System Wiring Methods. Medium- (3) Communications circuits in compliance with Article 800 power network-powered broadband communications sys- (4) Conductive optical fiber cables in compliance with Ar- tems shall be installed within buildings using listed Type ticle 770 BM or Type BMR, network-powered broadband communi- (5) Community antenna television and radio distribution cations medium power cables. systems in compliance with Article 820 (A) Ducts, Plenums, and Other Air-Handling Spaces. (d) Electric Light, Power, Class 1, Non—Powered Section 300.22 shall apply. Broadband Communications Circuit Cables. Network- (B) Riser: Cables installed in vertical runs and penetrating powered broadband communications cable shall not be more than one floor, or cables installed in vertical runs in a placed in any raceway, cable tray, compartment,outlet box, shaft, shall be Type BMR. Floor penetrations requiring junction box, or similar fittings with conductors of electric Type BMR shall contain only cables suitable for riser or light, power, Class 1, or non--power-limited fire alarm cir- plenum use. cuit cables. Exception No. 1: Type BM cables encased in metal race- Exception No. 1: Where all of the conductors of electric way or located in a fireproof shrift that has firestops at each light, power, Class 1, non—power-limited fire alarm circuits floor are separated from all of the network-powered broadband comm nic•ation.s cables by a petrtuanent barrier or listed Exceptive Nu. 2: Type BM cables in one- and two-family dwellings. divider. E.vc•eption No. 2: Power circuit conductors in outlet boxes, (C) Other Wiring. Cables installed in locations other junction boxes, or similar fittings or compartments where than the locations covered in 830.15](A) and (B) shall such conductors are introduced solely for power supply to be Type BM. the network-powered broadband communications system distribution equipment. The power circuit conductors shall E.rreptinrt: Tope BMU cable where the cable enters the be routed within the enclosure to maintain a minimum building from the outside and is run in rigid metal conduit 6-rem (0.25-in.) separation from network-powered broad- or intermediate metal conduit, and such conduits are Con- band communications cables. nected by a groundin8 Conductor to an electrode in accor- dance with 830.100(B). (2) Other Applications. Network-powered broadband communications cable shall be separated at least 50 mm 830.154 Applications of Low-Power Network-Powered (2 in.) from conductors of any electric light, power,Class 1, Broadband Communications System Cables.Low-power and non--power-limited fire alarm circuits. network-powered broadband communications systems shall Exception No. 1: Where either(1) all of the conductors of comply with any of the requirements of 830.154(A) electric light, power, Class 1, and non—power-limited fire through (C). alarm circuits are in a raceway, or in metal-sheathed, (A) Plenums.Cables installed in ducts,plenums, and other metal-clad, nonmetallic-sheathed, Type AC, or Type OF spaces used for environmental air shall be Type BLP. Type cables, or(2) all of the network-powered broadband com- BLX cable installed in compliance with 300.22 shall be munications cables are encased in raceway. permitted. Exception No. 2: Where the network powered broadband communications cables are permanently separated from the (B) Riser. Cables installed in risers shall comply with any conductors of electric light, power, Class 1, and non—of the requirements in 830.154(B)(1), (B)(2), or (B)(3). power-limited fire alarm circuits by a continuous and firmly (1) Cables in Vertical Runs. Cables installed in vertical fixed nonconductor, such as porcelain tubes or flexible tub- runs and penetrating more than one floor,or cables installed ing, in addition to the insulation on the wire. in vertical runs in a shaft, shall be Type BLP, BLR, or BMR. Floor penetrations requiring Type BMR or BLR ($) Support of Conductors. Raceways shall be used for shall contain only cables suitable for riser or plenum use. their intended purpose. Network-powered broadband com- munications cables shall not be strapped, taped, or attached (2) Metal Raceways or Fireproof Shafts. Type BLX by any means to the exterior of any conduit or raceway as cables shall be permitted to be encased in a metal raceway a means of support. or located in a fireproof shaft having firestops at each floor. 70-668 NATIONAL ELECTRICAL CODE 2008 Edition ARTICLE 830—NETWORK-POWERED BROADBAND COMMUNICATIONS SYSTEMS 830.179 (3) One- and Two-Family Dwellings. Type BLX or BL 830.160 Bends. Bends in network broadband cable shall cables less than 10 mm (0.375 in.) in diameter shall be be made so as not to damage the cable. permitted in one- and two-family dwellings. (C) Other Wiring Within Buildings. Cables installed in Vi. Listing Requirements locations other than those covered in 830.154(A) and (B) 830.179 Network-Powered Broadband Communications shall comply with the requirements of 830.154(C)(1) Equipment and Cables.Network-powered broadband com- through (C)(5). munications equipment and cables shall be listed as suitable (1) General. Type BLP, BL, or BM shall be permitted. for the purpose. (2) in Raceways. Type BLX shall be permitted to be in- Exception No. 1: This listing requirement shall not apply stalled in a raceway. to community antenna television and radio distribution sys- tem coaxial cables that were installed prior to January 1, (3) 'lope BLU Cable, Type BLU cable entering the build- 2000, in accordance with Article 820 and are used for ing from outside shall be permitted to be run in rigid metal low-power network Powered broadband communications conduit or intermediate metal conduit. Such conduits shall circuits. be connected by a grounding conductor to an electrode in Exception No. 2: Substitute cables for network-powered accordance with 830.100(B). broadband communications cables shall be permitted as (4) One- and Two-Family Dwellings. Type BLX or BL shown in Table 830.154. cables less than 10 mm (0.375 in.) in diameter shall be permitted to be installed in one- and two-family dwellings. (A) Listing and Marking. Listing and marking of network-powered broadband communications cables shall (5) Type BLX Cable. Type BLX cable entering the build- comply with 830.179(A)(1) or (A)(2), ing from outside and terminated at a grounding block or a primary protection location shall be permitted to be in- (1) Types BMU, BM, and BMR Cables. Network- stalled,provided that the length of cable within the building powered broadband communications medium-power under- does not exceed 15 m (50 ft). ground cable, Type BMU; network-powered broadband communications medium-power cable, Type BM; and FPN: This provision limits the length of Type BLX cable network-powered broadband communications medium- to 15 m (50 ft), while 830.90(B) requires that the primary power riser cable, Type BMR, shall be factory-assembled protector, or NIU with integral protection, be located as close as practicable to the point at which the cable enters cables consisting of a jacketed coaxial cable, a jacketed the building.Therefore, in installations requiring a primary combination of coaxial cable and multiple individual con- protector, or NIU with integral protection,Type BLX cable ductors, or a jacketed combination of an optical fiber cable may not be permitted to extend 15 m(50 ft) into the build- and multiple individual conductors. The insulation for the ing if it is practicable to place the primary protector closer individual conductors shall be rated for 300 volts mini- than 15 m (50 ft) to the entrance point. mum. Cables intended for outdoor use shall be listed as (D) Cable Substitutions. The substitutions for network- suitable for the application. Cables shall be marked in ac- powered broadband gables listed in Table 830.154 shall be cordance with 310.11. Type BMU cables shall be jacketed permitted.All cables in Table 830.154,other than network- and listed as being suitable for outdoor underground use. powered broadband cables, shall be coaxial cables. Type BM cables shall be listed as being suitable for general-purpose use,with the exception of risers and plenums, 830.157 Protection Against Physical Damage. Section and shall also be listed as being resistant to the spread of fire. 300.4 shall apply. Type BMR cables shall be listed as being suitable for use in a vertical run in a shaft or from floor to floor and shall also be Table 83Q.154 Cable Substitutions listed as having fire-resistant characteristics capable of pre- venting the carrying of fire from floor to floor. Cable FPN No. 1: One method of defining resistant to the spread Type Permitted Cable Substitutions g P of fire is that the cables do not spread fire to the top of the BM BMR tray in the "UL Flame Exposure,Vertical Tray Flame TeSt" BLP CMP, CL31? in UL I685-2000, Standard jbr Safety far Vertical-Tray BLR CMP, CL3P, CMR, CUR, BLP, BMR Fire-Propagation and Smoke Release Test for .Electrical BL CMP, CMR, CM, CMG, CUP, CUR, CL3, BMR, and Optical-Fiber Cables.The smoke measurements in the BM, BLP, BLR test method are not applicable. BLX CMP, CMR, CM, CMG, CMX, CUP, CL3R, CL3, Another method of defining resistant to the spread of fire CL3X, BMR, BM, BLP, BRP, BL is for the damage(char length)not to exceed 1.5 m(4 ft 11 in.) when performing the CSA"Vertical Flame Test—Cables in 2008 Edition NATIONAL ELECTRICAL CODE 70-669 830.179 ARTICLE 830—NETWORK-POWERED BROADBAND COMMUNICATIONS SYSTEMS Cable Trays," as described in CSA C22.2 No. 0.3-M-2001, be listed as having fire-resistant characteristics capable of Test Methods.far Electrical Wiles and Cables. preventing the carrying of fire from floor to floor.Type BLP FPN No. 2: One method of defining fire-resistant charac- cables shall be listed as being suitable for use in ducts, teristics capable of preventing the carrying of Ere from plenums, and other spaces used for environmental air and floor to floor is that the cables pass the requirements of shall also be listed as having adequate fire-resistant and low ANSIIUL 1666-2002.Standard Test for Flame Proprgation smoke-producing characteristics. Height of Electrical and Optical-Fiber Cable histalled Ver- tically in Shafts. FPN No. 1: One method of determining that cable is resis- tant to flame spread is by testing the cable to VW-1 (2) Types BLU, BLX, BL, BLR, and BLP Cables. (vertical-wire) flame test in ANSIIUL 1581-2001, Refer- Network-powered broadband communications low-power enc•e Standard for Elec•irical Wires, Cables and Flexible underground cable, Type BLU; limited-use network- Cords. powered broadband communications low-power cable, FPN No. 2: One method of defining resistant to the spread Type BLX; network-powered broadband communications of fire is that the cables do not spread fire to the top of the low-power cable, Type BL; network-powered broadband tray in the"UL Flame Exposure,Vertical Tray Flame Test' communications low-power riser cable, Type BLR; and in UL 1685-2000, Standard fbr Safety for Vertical-Trap network-powered broadband communications low-power Fire-Propasallon and Smoke-Release Test for Electrical plenum cable,Type BLP, shall be factory-assembled cables and Optical-Fiber Cables.The smoke measurements in the test method are not applicable. consisting of a jacketed coaxial cable, a jacketed combina- Another method of defining resistant to the spread of tion of coaxial cable and multiple individual conductors, or fire is for the damage(char length)not to exceed 1.5 m(4 ft a jacketed combination of an optical fiber cable and mul- I1 in.) when performing the CSA"Vertical Flame Test tiple individual conductors. The insulation for the indi- Cables in Cable Trays," as described in CSA 022,2 No. vidual conductors shall be rated for 300 volts minimum. 0.3-M-2001,Test Methodsfor Electrical Wigs and Cables. Cables intended for outdoor use shall be listed as suitable FPN No. 3: One method of defining fire-resistant charac- for the application. Cables shall be marked in accordance tefisties capable of preventing the carrying of fire from Type BLU cables shall be jacketed and listed floor to floor is that the cables pass the requirements of with 310.11. T YP J ANSI/UL 1666-1997,Standard Test far Flame Propagation as being suitable for outdoor underground use. Type BLX Height of Electrical and Optical-Fiber Cable Installed Ver- limited-use cables shall be listed as being suitable for use tic•ally in Shafts. outside, for use in dwellings, and for use in raceways and FPN No. 4: One method of defining a cable that is low shall also be listed as being resistant to flame spread. Type smoke-producing cable and fire-resistant cable is that the BL cables shall be listed as being suitable for general- cable exhibits a maximum peak optical density of 0.5 or purpose use, with the exception of risers and plenums, and less,an average optical density of 0.15 or less,and a maxi- shall also be listed as being resistant to the spread of fire. mum flame spread distance of 1.52 m (5 ft) or less when tested in accordance with NFPA 262-2007, Standard Type BLR cables shall be listed as being suitable for use in Method rf Test for Flame Travel and Smoke of Wires and a vertical run in a shaft or from floor to floor and shall also Cables for Use in Air-Handling Spaces, 70-670 NATIONAL ELECTRICAL CODF 2008 Edition TABLES Chapter 9 Tables Table 1 Percent of Cross Section of Conduit and Tubing for tubing fill. The actual dimensions of the equipment Conductors grounding or bonding conductor (insulated or bare) shall be used in the calculation. Number of Conductors All Conductor lWpes (4) Where conduit or tubing nipples having a maximum 1 53 length not to exceed 600 mm (24 in.) are installed be- t 31 tween boxes, cabinets, and similar enclosures, the Over 2 40 nipples shall be permitted to be filled to 60 percent of their total cross-sectional area, and 310.15(B)(2)(a) ad- FPN No. 1: Table l is based on common conditions of justment factors need not apply to this condition. proper cabling and alignment of conductors where the length of the pull and the number of bends are within rea- (5) For conductors not included in Chapter 9, such as mul- sonable limits. It should be recognized that,for certain con- ticonductor cables, the actual dimensions shall be used. ditions, a larger size conduit or a lesser conduit fill should be considered. (6) For combinations of conductors of different sizes, use i Table 5 and Table 5A for dimensions of conductors and FPN No. f When pulling three conductors or cabers into Table 4 for the applicable conduit or tubing dimensions. raceway, f the ratio of the raceway (inside diameter)to the e conductor or cable (outside diameter) is between 2.8 and (7) When calculating the maximum number of conductors 3.2, jamming can occur. While jamming can occur when permitted in a conduit or tubing, all of the same size pulling four or more conductors or cables into a raceway, the probability is very law. (total cross-sectional area including insulation), the next higher whole number shall be used to determine Notes to Tables the maximum number of conductors permitted when (1) See Annex C for the maximum number of conductors the calculation results in a decimal of 0.8 or larger. and fixture wires, all of the same size (total cross- (8) Where bare conductors are permitted by other sections sectional area including insulation) permitted in trade of this Code, the dimensions for bare conductors in sizes of the applicable conduit or tubing. Table 8 shall be permitted. (2) Table i applies only to complete conduit or tubing sys- (9) A multiconductor cable or flexible cord of two or more tems and is not intended to apply to sections of conduit conductors shall be treated as a single conductor for or tubing used to protect exposed wiring from physical calculating percentage conduit fill area. For cables that damage. have elliptical cross sections, the cross-sectional area (3) Equipment grounding or bonding conductors, where in- calculation shall be based on using the major diameter stalled, shall be included when calculating conduit or of the ellipse as a circle diameter. Table 2 Radius of Conduit and Tubing Bends One Shot and Full Shoe Conduit or Tubing Size Benders Other Bends Metric Designator Trade Size mm in. mm in. 16 1/2 101.6 4 101.6 4 21 314 114.3 41/2 127 5 27 1 146.05 53/4 152.4 6 35 1'/a 184.15 71/4 203.2 8 41 1'/2 209.55 8'/4 254 10 53 2 241.3 9'/2 304.8 12 63 2'/z 266.7 10'/2 381 15 78 3 330.2 13 457.2 18 91 3'/2 381 15 533.4 21 103 4 406.4 16 609.6 24 129 5 609.6 24 762 30 155 6 762 30 914.4 36 2008 Edition NATIONAL ELLCTRtCAL CooE 70-671 TABLES Table 4 Dimensions and Percent Area of Conduit and Tubing (Areas of Conduit or Tubing for the Combinations of Wires Permitted in Table 1, Chapter 9) Article 358-Electrical Metallic Tubing (EMT) Nominal Internal Total Area 1 Wire 2 Wires Over 2 Wires Diameter 100% 60% 53% 31% 40% Metric Trade Designator Size mm in. mm2 in.2 HIM in.2 mm2 in 2 min in.2 mm in.2 16 1/ 15.8 0.622 196 0.304 118 0.182 104 0.161 61 0.094 78 0.122 21 '/a 20.9 0.824 343 0.533 206 0.320 182 0.283 106 0.165 137 0.213 27 1 26.6 1.049 556 0.864 333 0.519 295 0.458 172 0.268 222 0.346 35 1'/4 35.1 1380 968 1.496 581 0.897 513 0.793 300 0.464 387 0.598 41 11/ 40.9 1.610 1314 2.036 788 1.221 696 1.079 407 0.631 526 0.814 53 2 52.5 2.067 2165 3.356 1299 2.013 1147 1.778 671 1.040 866 1.342 63 2'/ 69.4 2.731 3783 5.858 2270 3.515 2005 3.105 1173 1.816 1513 2.343 78 3 85.2 3.356 5701 8,846 3421 5.307 3022 4.688 1767 2.742 2280 3.538 91 3'/ 97.4 3.834 7451 11.545 4471 6.927 3949 6.119 2310 3.579 2980 4.618 103 4 110.1 4.334 9521 14.753 5712 8.852 5046 7.819 2951 4.573 3808 5.901 Article 362-Electrical Nonmetallic Tubing(ENT) Nominal Internal Total Area 1 Wire 2 Wires Over 2 Wires Diameter 100% 60% 53% 31% 40% Metric Trade Designator Size mm in. mm in.2 mm in.2 mm2 in.2 MITI 2 in 2 mm2 in.2 16 '/ 14.2 0.560 158 0.246 95 0.148 84 0.131 49 0.076 63 0.099 21 '/4 19.3 0.760 293 0.454 176 0.272 155 0.240 91 0.141 117 0.181 27 1 25.4 1.000 507 0.785 304 0.471 269 0.416 157 0.243 203 0.314 35 1'/4 34.0 1.340 908 1.410 545 0.846 481 0.747 281 0.437 363 0.564 41 P/2 39.9 1.570 1250 1.936 750 1.162 663 1.026 388 0.600 500 0.774 53 2 513 2.020 2067 3.205 1240 1.923 1095 1.699 641 0.993 827 1.282 63 21/2 ---� - - - - - - -- - - - - 78 3 - 91 3y - - - - - - - - - - Article 348-Flexible Metal Conduit(FMC1 Nominal Internal Total Area 1 Wire 2 Wires Over 2 Wires Diameter 100% 60% 53% 31% 40% Metric Trade Designator Size mm in. min in.2 min.2. in.2 mm2 in? Mm in.2 Film in.2 12 '/r 9.7 0.384 74 0.116 44 0.069 39 0.061 23 0.036 30 0.046 16 1/ 16.1 0.635 204 0.317 122 0.190 108 0.168 63 0.098 81 0.127 21 °/a 20.9 0.824 343 0.533 206 0.320 182 0.283 106 0.165 137 0.213 27 1 25.9 1.020 527 0.817 316 0.490 279 0.433 163 0.253 211 0.327 35 1'/a 32.4 1.275 824 1.277 495 0.766 437 0.677 256 0.396 330 0.511 41 1'/ 39.1 1.538 1201 1.858 720 1.115 636 0.985 372 0.576 480 0.743 53 2 51.8 2.040 2107 3.269 1264 1.961 1117 1.732 653 1.013 843 1.307 63 2'/ 63.5 2.500 3167 4.909 1900 2.945 1678 2.602 982 1.522 1267 1.963 78 3 76.2 3.000 4560 7.069 2736 4.241 2417 3.746 1414 2.191 1824 2.827 91 31/ 88.9 3.500 6207 9.621 3724 5.773 3290 5.099 1924 2.983 2483 3.848 103 4 101.6 4.000 8107 12.566 4864 7.540 4297 6.660 2513 3,896 3243 5.027 70-672 NATIONAL ELECTRICAL CODE 2008 Edition TABLES Table 4 Continued Article 342-Intermediate Metal Conduit (IMC) Nominal Internal Total Area 1 Wire 2 Wires Over 2 Wires Diameter 100% 60% 53% 31% 40% Metric Trade Designator Size mm in. mm in.2 mm in.2 mm in.2 mm2 in.2 mm in.2 12 °/a - - - - - - - - - 16 1/2 16.8 0.660 222 0.342 133 0.205 117 0.181 69 0.106 89 0.137 21 /4 21.9 0.864 377 0.586 226 0.352 200 0.311 117 0.182 151 0.235 27 1 28.1 1.105 620 0.959 372 0.575 329 0.508 192 0.297 248 0,384 35 1114 36.8 1.448 1064 1.647 638 0.988 564 0.873 330 0.510 425 0.659 41 1112 42.7 1.683 1432 2.225 859 1,335 759 1.179 444 0.690 573 0.890 53 2 54.6 2.150 2341 1630 1405 2,178 1241 1.924 726 1,125 937 1.452 63 2'/2 64.9 2.557 3308 5.135 1985 3.981 1753 2.722 1026 1.592 1323 2.054 78 3 80.7 3.176 5115 7.922 3069 4.753 2711 4.199 1586 2.456 2046 3.169 91 31/ 93.2 3.671 6822 10.584 4093 6.351 3616 5.610 2115 3.281 2729 4.234 103 4 105.4 4.166 8725 13.631 5235 8.179 4624 7.224 2705 4.226 3490 5.452 Article 356- Liquidtight Flexible Nonmetallic Conduit (LFNC-B*) Nominal Internal Total Area I Wire 2 Wires Over 2 Wires Diameter 100% 60% 53% 31% 40% Metric Trade Designator Size mm in. mm in.2 mm in.Z mm in.2 mm in.2 mm in.2 12 A 12.5 0.494 123 0.192 74 0.115 65 0.102 38 0.059 49 0.077 16 V2 16.1 0.632 204 0.314 122 0.188 108 0.166 63 0.097 81 0.125 21 /4 21.1 0.830 350 0.541 210 0.325 185 0,287 108 0.168 140 0.216 27 1 26.8 1.054 564 0.873 338 0.524 299 0.462 175 0.270 226 0.349 35 11/4 35.4 1.395 984 1.528 591 0.917 522 0.810 305 0.474 394 0.611 41 11/2 40.3 1.588 1276 1.981 765 1.188 676 1.050 395 0,614 510 0.792 53 2 51.6 2.033 2091 1246 1255 1,948 1108 1.720 648 1.006 836 1.298 *Corresponds to 356.2(2) Article 356-Liquidtight Flexible Nonmetallic Conduit (LFNC-A*) Nominal Internal Total Area 1 Wire 2 Wires Over 2 Wires Diameter 100% 60% 53% 31% 40% Metric Trade Designator Size mm in. Mm in.2 mm in.2 mm in.2 mm in.2 mm in.2 12 1/8 12.6 0.495 125 0.192 75 0.115 66 0.102 39 0.060 50 0.077 16 1/2 16,0 0.630 201 0.312 121 0.187 107 0.165 62 0,097 80 0.125 21 ;/4 21.0 0.825 346 0.535 208 0.321 184 0.283 107 0.166 139 0.214 27 1 26.5 1.043 552 0.854 331 0.513 292 0.453 171 0.265 221 0.342 35 1'14 35.1 1.383 968 1.502 581 0.901 513 0.796 300 0.466 387 0.601 41 P12 40.7 1,603 1301 2.018 781 1.211 690 1.070 403 0.626 520 0.807 53 2 52.4 2.063 2157 3.343 1294 2.006 1143 1.772 669 1.036 863 1.337 *Corresponds to 356.20) (Continues) 2008 Edition NATIONAL ELECTRICAL CODE 70-673 TABLES Table 4 Continued Article 350-Uquidtight Flexible Metal Conduit (LFMC) Nominal Internal Total Area 1 Wire 2 Wires Over 2 Wires Diameter 100% 60% 53% 31% 40% Metric 'Dade Designator Size mm in. mm2 in.' MIN 1n.2 mm2 in.2 min in.2 min in.2 12 ;/K 12.5 0.494 123 0.192 74 0.115 65 0.102 38 0.059 49 0.077 16 '/ 16.1 0.632 204 0.314 122 0,188 108 0.166 63 0.097 81 0.125 21 ;/4 21.1 0.830 350 0.541 210 0.325 185 0.287 108 0.168 140 0.216 27 1 26.8 1.054 564 0.873 338 0.524 299 0.462 175 0.270 226 0.349 35 11/4 35.4 1.395 984 1.528 591 0.917 522 0.810 305 0.474 394 0.611 41 11h 40.3 1.588 1276 1.981 765 1.188 676 1.050 395 0.614 510 0.792 53 2 51.6 2.033 2091 3.246 1255 1.948 1108 1.720 648 1.006 836 1.298 63 2'/2 63.3 2.493 3147 4.881 1888 2.929 1668 2.587 976 1.513 1259 1.953 78 3 78.4 3.085 4827 7.475 2896 4.485 2559 3.962 1497 2.317 1931 2.990 91 311-, 89.4 3.520 6277 9.731 3766 5.839 3327 5.158 1946 3.017 2511 3.893 103 4 102.1 4.020 8187 12.692 4912 7.615 4339 6.727 2538 3.935 3275 5.077 129 5 - - - -- - - - - - - - - 155 6 - - - - - - - - - - - Article 344-Rigid Metal Conduit (RMC) Nominal Internal Total Area 1 Wire 2 Wires Over 2 Wires Diameter 100% 60% 53% 31% 40% Metric 'Dade Designator Size mm in. min iR.-2 min in.2 mm'2 in.2 min in Z EM in.2 12 %s - -- - - - - - -- -- _ 16 112 16.1 0.632 204 0.314 122 0.188 108 0.166 63 0.097 81 0.125 21 1/4 21.2 0.836 353 0.549 212 0.329 187 0.291 109 0.170 141 0.220 27 1 27.0 1.063 573 0.887 344 0.532 303 0.470 177 0.275 229 0.355 35 11/4 35.4 1.394 984 1.526 591 0.916 522 0.809 305 0.473 394 0.610 41 P/2 41.2 1.624 1333 2.071 800 1.243 707 1.098 413 0.642 533 0.829 53 2 52.9 2.083 2198 3.408 1319 2.045 1165 1.806 681 1.056 879 1.363 63 21/2 63.2 2.489 3137 4.866 1882 2.919 1663 2.579 972 1.508 1255 1.946 78 3 78.5 3.090 4840 7.499 2904 4.499 2565 3.974 1500 2.325 1936 3.000 91 31/ 90.7 3.570 6461 10.010 3877 6.006 3424 5.305 2003 3.103 2584 4.004 103 4 102.9 4.050 8316 12.882 4990 7.729 4408 6.828 2578 3.994 3326 5.153 129 5 128.9 5.073 13050 20.212 783012.127 6916 10.713 4045 6.266 5220 8.085 155 6 154.8 6.093 18821 29.158 1129217.495 9975 15.454 5834 9.039 7528 11.663 Article 352---Rigid PVC Conduit(PVC),Schedule 80 Nominal Internal Total Area 1 Wire 2 Wires Over 2 Wires Diameter 100% 60% 53% 31% 40% Metric Trade Designator Size mm in. mm2 in.2 min in.2 min in.2 min in. min in.2 12 '/x - - -- - - - - - - - - - 16 1/2 13.4 0.526 141 0.217 85 0.130 75 0.115 44 0.067 56 0.087 21 1/4 18.3 0.722 263 0.409 I58 0.246 139 0.217 82 0.127 105 0.164 27 1 23.8 0.936 445 0.688 267 0.413 236 0.365 138 0.213 178 0.275 35 11/4 31.9 1.255 799 1.237 480 0.742 424 0.656 248 0.383 320 0.495 41 H/2 37.5 1.476 1104 1.711 663 1.027 585 0.907 342 0.530 442 0.684 53 2 48.6 1.913 1855 2.874 1113 1.725 983 1.523 575 0.891 742 L150 63 21/2 58.2 2.290 2660 4.119 1596 2.471 1410 2.183 825 1.277 1064 1.647 78 3 72.7 2.864 4151 6.442 2491 3.865 2200 3.414 1287 1.997 1660 2.577 91 31/2 84.5 3.326 5608 8.688 3365 5.213 2972 4.605 1738 2.693 2243 3.475 103 4 96.2 3.786 7268 11.258 4361 6.755 3852 5.967 2253 3.490 2907 4.503 129 5 121.1 4.768 11518 17.855 6911 10.713 6105 9.463 3571 5.535 4607 7.142 155 6 145.0 5.709 16513 25.598 9908 15.359 8752 13.567 5119 7.935 6605 10.239 70-674 NATIONAL ELECTRICAL CODE 2008 Edition TABLES Table 4 Continued Articles 352 and 353- Rigid PVC Conduit (PVC), Schedule 40,and HDPE Conduit (HDPE) Nominal Internal Total Area 1 Wire 2 Wires Over 2 Wires Diameter 100% 60% 53% 31% 40% Metric Trade Designator Size mm in. mm in.2 mm in.2 mm in 2 mm 2 in.2 mm2 in? 12 '/K - - - __. - - - - - - 16 '12 15.3 0.602 184 0.285 110 0.171 97 0.151 57 0.088 74 0.114 21 '/4 20.4 0.804 327 0.508 196 0.305 173 0.269 101 0.157 131 0.203 27 1 26.1 1.029 535 0.832 321 0.499 284 0.441 166 0,258 214 0.333 35 11/4 34.5 1.360 935 1.453 561 0.872 495 0.770 290 0.450 374 0.581 41 11/ 40.4 1.590 1282 1.986 769 1.191 679 1.052 397 0.616 513 0.794 53 2 52.0 1047 2124 3.291 1274 1.975 1126 1.744 658 1.020 849 1.316 63 21/ 62.1 2.445 3029 4.695 19P 7 2.817 1605 2.488 939 1.455 1212 1.878 78 3 77.3 3.042 4693 7.268 2816 4.361 2487 3.852 1455 2.253 1877 2.907 91 31/ 89.4 3.521 6277 9.737 3766 5.842 3327 5.161 1946 3.018 2511 3.895 103 4 101.5 3.998 8091 12.554 4855 7.532 4288 6.654 2508 3.892 3237 5.022 129 5 127.4 5.016 12748 19.761 764911.856 6756 10.473 3952 6.126 5099 7.904 155 6 153.2 6.031 18433 28.567 1106017.140 9770 15.141 5714 8.856 7373 11.427 Article 352-Type A, Rigid PVC Conduit(PVC) Nominal Internal Total Area 1 Wire 2 Wires Over 2 Wires Diameter 100% 60% 53% 31% 40% Metric Trade Designator Size mm in. mm in.2 mm` in.2 mm in.' mm in.2 mm in.2 16 1/2 17.8 0.700 249 0.385 149 0.231 132 0.204 77 0.119 100 0.154 21 ;/1 23.1 0.910 419 0,650 251 0.390 222 0.345 130 0.202 168 0.260 27 l 29.8 1.175 697 1.084 418 0,651 370 0.575 216 0.336 279 0.434 35 11/4 38.1 1.500 1140 1.767 684 1.060 604 0.937 353 0.548 456 0.707 41 1112 43.7 1.720 1500 2.324 900 1.394 795 1.231 465 0.720 600 0.929 53 2 54.7 2.155 2350 3.647 1410 2.188 1245 1.933 728 1.131 940 1.459 63 21/: 66.9 2.635 3515 5.453 2109 3.272 1863 2.890 1090 1.690 1406 2.181 78 3 82.0 3.230 5281 8.194 3169 4.916 2799 4.343 1637 2.540 2112 3.278 91 31/i 93.7 3.690 6896 10.694 4137 6.416 3655 5.668 2138 3.315 2758 4.278 103 4 106.2 4.180 8858 13.723 5315 8.234 4695 7.273 2746 4.254 3543 5.489 129 5 - - --- -- - - - - - --® - - 155 6 - - - - - - - - - - Article 352-Type EB, Rigid PVC Conduit(PVC) Nominal Internal Total Area 1 Wire 2 Wires Over 2 Wires Diameter I00% 60% 53% 31% 40% Metric Trade Designator Size mm in. mm2 in.2 mm in.2 mm2 in.2 mm in.2 mm in.2 16 1/2 - - - - - - -- - - - 21 '/4 - - - - - - -- - - 27 1 - - - 35 PA - - - - - - - - - - 41 1'/= - - - - - - - - - - - 53 2 56.4 2.221 2498 3.874 1499 2.325 1324 2.053 774 1.201 999 1.550 63 21/2 - - - - - - - - - - - - 78 3 84.6 3.330 5621 8.709 3373 5.226 2979 4.616 1743 2.700 2248 3.484 91 31/ 96.6 3.804 7329 11.365 4397 6.819 3884 6.023 2272 3.523 2932 4.546 103 4 108.9 4.289 9314 14.448 5589 8.669 4937 7.657 2887 4.479 3726 5.779 129 5 135.0 5.316 14314 22.195 8588 13.317 7586 11.763 4437 6.881 5726 8.878 155 6 160.9 6.336 20333 31.530 1220018.918 10776 16.711 6303 9.774 8133 12.612 2(X)8 Edition NATIONAL ELECTRICAL CODE 70-675 TABLES Table 5 Dimensions of Insulated Conductors and Fixture Wires Size (AWG or Approximate Diameter Approximate Area Type kcmil) mm in, mm in.2 Type: FFH-2, RFH-1, RFH-2, RHH*, RHW*, RHW-2*,RHH, RHW, RHW-2, SF-1, SF-2, SFF-1,SFF-2,TF, TFF,THHW, THW,THW-2,TW,XF, XFF RFH-2, 18 3.454 0.136 9.355 0.0145 FFH-2 16 3.759 0.148 11.10 0.0172 RHH, RHW, 14 4.902 0.193 18.90 0.0293 RHW-2 12 5.385 0.212 22.77 0.0353 10 5.994 0.236 28.19 0.0437 8 8.280 0.326 53.87 0.0835 6 9.246 0.364 67.16 0.1041 4 10.46 0.412 86.00 0.1333 3 11.18 0.440 98.13 0.1521 2 11.99 0.472 112.9 0.1750 1 14.78 0.582 171.6 0.2660 110 15.80 0.622 196.1 0.3039 2/0 16.97 0.668 226.1 0.3505 310 18.29 0.720 262.7 0.4072 4/0 19.76 0.778 306.7 0.4754 250 22.73 0.895 405.9 0.6291 300 24.13 0.950 457.3 0.7088 350 25.43 1.001 507.7 0.7870 400 26.62 1.048 556.5 0.8626 500 28.78 1.133 650.5 1.Q082 600 31.57 1.243 782.9 1.2135 700 33.38 1.314 874.9 1.3561 750 34.24 1.348 920.8 1.4272 800 35.05 1.380 965.0 1.4957 900 36.68 1.444 1057 1.6377 1000 38.15 1.502 1143 1.7719 1250 43.92 1.729 1515 2.3479 1500 47.04 1.852 1738 2.6938 1750 49.94 1.966 1959 3.0357 2000 52.63 2.072 2175 3.3719 SF-2, SFF-2 18 3.073 0.121 7.419 0.0115 16 3.378 0.133 8.968 0.0139 14 3.759 0.148 H.10 0.0172 SF-1, SFF-1 18 2.311 0.091 4.194 0.0065 RFH-1, XF, XFF 18 2.692 0.106 5.161 0.0080 TF,TFF, XF, XFF 16 2.997 0.118 7.032 0.0109 TW, XF, XFF, 14 3.378 0.133 8.968 0.0139 THHW,THW, THW-2 70-676 NATIONAL ELECTRICAL CODE 2008 Edition TABLES Table 5 Continued Approximate Diameter Approximate Area Size(AWG or Type kcmil) mm in. mm2 in? TW,THHW, 12 3.861 0.152 11.68 0.0181 THW, THW-2 10 4.470 0.176 15.68 0.0243 8 5.994 0.236 28.19 0.0437 RHH*, RHW*, 14 4.140 0.163 13.48 0.0209 RHW-2* RHH*, RHW*, 12 4.623 0.182 16.77 0.0260 RHW-2*, XF, XFF Type: RHH*, RHW*, RHW-2*,THHN,THHW,THW,THW-2,TFN,TFFN,THWN, THWN-2, XF, XFF RHH,* RHW,* 10 5.232 0.206 21.48 0.0333 RHW-2,* XF, XFF RHH*, RHW*, 8 6.756 0.266 35.87 0.0556 RHW-2* TW,THW, 6 7.722 0.304 46.84 0.0726 THHW,THW-2, 4 8.941 0.352 62.77 0.0973 RHH*, RHW*, 3 9.652 0.380 73.16 0.1134 RHW-2* 2 10.46 0.412 86.00 0.1333 1 12.50 0.492 122.6 0.1901 1/0 13.51 0.532 143.4 0.2223 210 14.68 0.578 169.3 0.2624 310 16.00 0.630 201.1 0.3117 410 17.48 0.688 239.9 0.3718 250 19.43 0.765 296.5 0.4596 300 20.83 0.820 340.7 0.5281 350 22.12 0.871 384.4 0.5958 400 23.32 0.918 427.0 0.6619 500 25.48 1,003 509.7 0.7901 600 28.27 1.113 627.7 0.9729 700 30.07 1.184 710.3 1.1010 750 30.94 1.218 751.7 1.1652 800 31.75 1.250 791.7 1,2272 900 33.38 1.314 874.9 1.3561 1000 34.85 1.372 953.8 1.4784 1250 39.09 1.539 1200 1.8602 1500 42.21 1.662 1400 2.1695 1750 45.11 1.776 1598 2.4773 2000 47.80 1.882 1795 2.7818 TFN, TFFN 18 2.134 0.084 3.548 0.0055 16 2.438 0.096 4.645 0.0072 (Continries) 2048 Edition NATIONAL ELECTRICAL CODE 70477 TABLES Table 5 Continued Size (A-vVG or Approximate Diameter Approximate Area Type kcmil) mm in. mm in.2 THHN,THWN, 14 2.819 0.111 6.258 0.0097 THWN-2 12 3.302 0.130 8.581 0.0133 10 4.166 0.164 13.61 0.0211 8 5.486 0.216 23.61 0.0366 6 6.452 0.254 32.71 0.0507 4 8.230 0.324 53.16 0.0824 3 8.941 0.352 62.77 0.0973 2 9.754 0.384 74.71 0.1158 1 11.33 0.446 100.8 0.1562 1/0 12.34 0.486 119.7 0.1855 2/0 13.51 0.532 143.4 0.2223 310 14.83 0.584 172.8 0.2679 4/0 16.31 0.642 208.8 0.3237 250 18.06 0.711 256.1 0.3970 300 19.46 0.766 297.3 0,4608 Type: FEP, FEPB, PAF, PAFF,PF, PFA,PFAH, PFF, PGF, PGFF, PTF,PTFF,TFE,THHN,THWN,THWN-2, Z, ZF,ZFF THHN, THWN, 350 20.75 0.817 338.2 0.5242 THWN-2 400 21.95 0.864 378.3 0.5863 500 24.10 0.949 456.3 0.7073 600 26.70 1.051 559.7 0.8676 700 28.50 1.122 637.9 0.9887 750 29.36 1.156 677.2 1.0496 800 30.18 1.188 715.2 1.1085 900 31.80 1.252 794.3 1.2311 1000 33.27 1.310 869.5 1,3478 PF, PGFF, PGF, 18 2.184 0.086 3.742 0.0058 PFF PTF, PAF, 16 2.489 0.098 4.839 0.0075 PTFF, PAFF PF, PGFF, PGF, 14 2.870 0.113 6.452 0.0100 PFF PTF, PAF, PTF)~, PAFF, TFE, FEP, PFA, FEPB, PFAH TFE, FEP, PFA, 12 3.353 0.132 8.839 0.0137 FEPB, PFAH l0 3.962 0.156 12.32 0.0191 8 5.232 0.206 21.48 0.0333 6 6.198 0.244 30.19 0.0468 4 7.417 0.292 43.23 0.0670 3 8.128 0.320 51.87 0.0804 2 8.941 0.352 62.77 0.0973 TFE. PFAH 1 10.72 0.422 90.26 0.1399 TFE, PFA, PFAH, 1/0 11.73 0.462 108.1 0.1676 Z 2/0 12.90 0.508 130.8 0.2027 310 14.22 0.560 158.9 0.2463 4/0 15.70 0.618 193.5 0.3000 ZF ZFF 18 1.930 0.076 2.903 0.0045 16 2.235 0.088 3.935 0.0061 7"78 NATIONAL ELECTRICAL CODE 2008 Edition TABLES Table 5 Continued Approximate Diameter Approximate Area Size (AWG or Type kemil) mm in. MM in.2 Z, ZF, ZFF 14 2.616 0.103 5.355 0.0083 Z 12 3.099 0.122 7.548 0.0117 10 3.962 0.156 12.32 0.0191 8 4.978 0.196 19.48 0.0302 6 5.944 0.234 27.74 0.0430 4 7.163 0.282 40.32 0.0625 3 8.382 0.330 55.16 0.0855 2 9.195 0.362 66.39 0.1029 1 10.21 0.402 81.87 0.1269 Type: KF-1, KF-2, KFF-1, KFF-2, XHH,XHHW, XHHW-2, ZW XHHW, ZW, 14 3.378 0.133 8.968 0.0139 XHHW-2, XHH 12 3.861 0.152 11.68 0.0181 10 4.470 0.176 15.68 0.0243 8 5.994 0.236 28.19 0.0437 6 6.960 0.274 38.06 0.0590 4 8.179 0.322 52.52 0.0814 3 8.890 0.350 62.06 0.0962 2 9.703 0.382 73.94 0,1146 XHHW, 1 11.23 0.442 98.97 0.1534 XHHW-2, XHH 110 12.24 0.482 117.7 0.1825 210 13.41 0.528 141.3 0.2190 310 14.73 0.58 170.5 0.2642 410 1 6.21 0.638 206.3 0.3197 250 17.91 0.705 251.9 0.3904 300 19.30 0.76 292.6 0.4536 350 20.60 0.811 333.3 0.5166 400 21.79 0.858 373.0 0.5782 500 23.95 0.943 450.6 0.6984 600 26.75 1.053 561.9 0.8709 700 28.55 1.124 640.2 0.9923 750 29.41 1.158 679.5 0532 800 30.23 1.190 717.5 :.1122 900 31.85 1.254 796.8 :?351 1(0) 33.32 1.312 872.2 1.3519 1250 37.57 1.479 1108 1.7180 1500 40.69 1.602 1300 2.0157 1750 43.59 1.716 1492 2.3127 2000 46.28 1.822 1682 2.6073 KF-2, KFF-2 18 1.600 0.063 2.000 0.0031 16 1.905 0.075 2.839 0.0044 14 2.296 0.090 4.129 0.0064 12 2.769 0.109 6.000 0.0093 10 3.378 0.133 8.968 0.0139 KF-1, KFF-1 18 1.448 0.057 1.677 0.0026 16 1.753 0.069 2.387 0.0037 14 2.134 0.084 3.548 0.0055 12 2.616 0,103 5.355 0.0083 10 3.226 0.127 8.194 0.0127 *Types RHH, RHW, and RHW-2 without outer covering. 2008 Edition NATIONAL ELECTRICAL CODE 70-679 TABLES Table 5A Compact Copper and Aluminum Building Wire Nominal Dimensions* and Areas Bare Conductor Types THW and THEW Type THHN Type XHHW Size Approximate Approximate Approximate Approximate Approximate Approximate Size (AWG Diameter Diameter Area Diameter Area Diameter Area (AWG or or kcmil) mm in. mm in. mm 2 in.' mm in. mm2 in.2 mm in. min2 in.2 kcmii) 8 3.404 0.134 6.477 0.255 32.900.0510 - - - - 5.690 0.224 25.42 0.0394 8 6 4.293 0.169 7.366 0.290 42.580.0660 6.096 0.240 29.16 0.0452 6.604 0.260 34,19 0.0530 6 4 5.410 0.213 8.509 0.335 56.840.0881 7.747 0.305 47.10 0.0730 7.747 0.305 47.10 0.0730 4 2 6.807 0.268 9.906 0.390 77.030.1194 9.144 0.360 65.61 0.1017 9.144 0.360 65.61 0.1017 2 1 7.595 0.299 11.81 0.465 109.5 0.1698 10.54 0.415 87.23 0.1352 10.54 0.415 87.23 0.1352 1 110 8.534 0.336 12,70 0.500 126.6 0.1963 11.43 0.450 102.6 0.1590 11.43 0.450 102.6 0.1590 110 210 9.550 0.376 13.84 0.545 150.5 02332 12.57 0.495 124.1 0.1924 12.45 0.490 121.6 0.1885 210 310 10.74 0.423 14,99 0.590 176.3 0.2733 13.72 0.540 147.7 0.2290 13.72 0.540 147.7 0.2290 310 410 12.07 0.475 16.38 0.645 210.8 0.3267 15.11 0.595 179.4 0.2780 14.99 0.590 176.3 0.2733 410 250 13.21 0.520 18.42 0.725 266.3 0.4128 17.02 0.670 227.4 0.3525 16.76 0.660 220.7 0.3421 250 300 14,48 0.570 19.69 0,775 304.3 0.4717 18.29 0.720 262.6 0.4071 18.16 0.715 259.0 0.4015 300 350 15.65 0.616 20.83 0.820 340.7 0.5281 19.56 0.770 300.4 0.4656 19.30 0.760 292.6 0.4536 350 400 16,74 0,659 21,97 0.865 379.1 0.5876 20.70 0.815 336.5 0,5216 20.32 0.800 324.3 0.5026 400 500 18.69 0.736 23.88 0.940 447.7 0.6939 22.48 0.885 396.8 0.6151 22.35 0.880 392.4 0.6082 500 600 20.65 0.813 26.67 1.050 558.6 0.8659 25.02 0,985 491.6 0.7620 24.89 0.980 486.6 0.7542 600 700 22.28 0.877 28.19 1.110 624.3 0.9676 26.67 1.050 558.6 0.8659 26.67 1.050 558.6 0.8659 700 750 23.06 0.906 29.21 1.150 670.1 1.0386 27.31 1,075 585.5 0.9076 27.69 1.090 602.0 0.9331 750 900 25.37 0.999 31.09 1,224 759.1 1.1766 30.33 1.194 722.5 1.1196 29.69 1.169 692,3 1.0733 900 10(10 26.92 1.060 32.64 1.285 836.6 1.2968 31.88 1.255 798.1 1.2370 31.24 1.230 766.6 1.1882 1000 *Dimensions are from industry sources, 70-680 NATIONAL ELECTRICAL CODE 2008 Edition TABLES Table 8 Conductor Properties Conductors Direct-Current Resistance at 75°C(167°F) Stranding Overall Copper Size Area Diameter Diameter Area Uncoated Coated Aluminum (AW G or Circular ohm! ohm/ ohm/ ohm/ ohm/ obm/ kemil) tom' mils Quantity mm in. mm in. mm7' in 2 km kFT km kFF km kFF 18 0.823 1620 1 - - 1.02 0.040 0.823 0.001 25.5 7.77 26.5 8.08 42.0 12.8 18 0.823 1620 7 0.39 0.015 1.16 0.046 1.06 0.002 26.1 7.95 27.7 8.45 42.8 13.1 16 1.31 2580 1 - - 1.29 0.051 1.31 0.002 16.0 4.89 16.7 5.08 26.4 8.05 16 1.31 2580 7 0.49 0.019 1.46 0.058 1,68 0.003 16.4 4.99 17.3 5.29 26.9 8.21 14 2.08 4110 1 - - 1.63 0,004 2.08 0.003 10.1 3.07 10.4 3.19 16.6 5.06 14 2.08 4110 7 0.62 0.024 1.85 0.073 2.68 0.(x)4 103 3.14 10.7 3.26 16.9 5.17 12 3.31 6530 l - - 2.05 0.081 3.31 0.0(15 6.34 1.93 6.57 2.01 10.45 118 12 3.31 6530 7 0.78 0.030 132 0.092 4.25 0.(x)6 6.50 1.98 6.73 2.05 10.69 3.25 10 5.261 10380 1 - - 2.588 0.102 5.26 0.008 3.984 1.21 4.148 1.26 6.561 2.00 10 5.261 10380 7 0.98 0.038 2.95 0.116 6.76 0.011 4.070 124 4.226 1.29 6.679 2.04 8 8.367 16510 1 - 3.264 0.128 8.37 0.013 2.506 0.704 2.579 0.786 4,125 126 8 8.367 16510 7 1.23 0.049 3.71 0.146 10.76 0.017 2.551 0.778 2.653 0.809 4.204 128 6 13.30 26240 7 1.56 0.061 4.67 0.184 17.09 0.027 1.608 0.491 1.671 0.510 2.652 0.808 4 21.15 41740 7 1.96 0.077 5.89 0.232 27.19 0.042 1,010 0.308 1.053 0.321 1.666 0.508 3 26.67 52620 7 2.20 0.087 6.60 0.260 34.28 0.053 0.802 0.245 0.833 0.254 1.320 0.403 2 33.62 66360 7 2.47 0.097 7.42 0.292 43.23 0.067 0.634 0.194 0.661 0.201 1.045 0.319 1 42.41 83690 19 1.69 0,066 8.43 0.332 55.80 0.087 0.505 0.154 0.524 0.160 0,829 0.253 1/0 53.49 105600 19 1.89 0.074 9.45 0.372 70.41 0.109 0.399 0,122 0,415 0.127 0.660 0.201 2/0 67.43 133100 19 2.13 0.084 10.62 0.418 88.74 0,137 0.3170 0.0967 0.329 0.101 0,523 0.159 3/0 85.01 167800 19 2.39 0.094 11.94 0.470 111.9 0.173 0.2512 0.1766 0.2610 0.0797 0.413 0.126 4/0 107.2 211600 19 2.68 0.106 13.41 0.528 141.1 0.219 0.1996 0.0609 0.2050 0.0626 0.328 0.100 250 127 37 2.09 0.082 14.61 0.575 168 0.260 0.1687 0.0515 0.1753 0.0535 0.2778 0.01447 300 152 - 37 2.29 0,090 16.00 0.630 201 0.312 0.1409 0.0429 0.1463 0.0446 0.2318 0.0707 350 177 - 37 2.47 0.(197 17.30 0.681 235 0.364 0.1205 0.0367 0.1252 0.0382 0.1984 0.0605 400 203 - 37 2.64 0.104 18.49 0.728 268 0.416 0.1053 0.0321 0.1084 0.0331 0.1737 0.0529 500 253 - 37 2.95 0.116 20.65 0.813 336 0.519 0.0845 0.0258 0.0869 0.0265 0.1391 0,0424 600 304 - 61 2.52 0.099 22.68 0.893 404 0.626 0.0704 0.0214 0.0732 0.0223 0.1159 0.0353 7W 355 6l 2.72 0.107 24.49 0.964 471 0.730 0.0603 0.0184 0.0622 0.0189 0.0994 0.0303 750 380 61 2.82 0.111 25.35 0.998 505 0.782 0.0563 0.0171 0.0579 0.0176 0.0927 0.0282 800 405 61 2.91 0.114 26.16 1.030 538 0.834 0.0528 0.0161 0.0544 0.0166 0.0868 0.0265 900 456 - 61 3.09 0.122 27.79 1.094 606 0.940 IVA70 0.0143 0.0481 0.0147 0,0770 0.0235 10(x1 507 - 61 3.25 0.128 29.26 1.152 673 1.042 0.0423 0.0129 0.0434 0.0132 0.0695 0.0212 1250 633 - 91 2.98 0.117 32.74 1.289 842 1.305 0.0338 0.0103 0.0347 0.0106 0.0554 0.0169 1500 760 - 91 3.26 0.128 35.86 1,412 1011 1.566 0.02814 0.00858 0.02814 0.00883 0.0464 0.0141 1750 887 - 127 2.98 0.117 38.76 1.526 1180 1.829 0.02410 0.00735 0.02410 0.00756 0.0397 0.0121 2000 1013 - 127 3.19 0.126 41.45 1.632 1349 2.092 0.02109 0.00643 0.02109 0.00662 0,0348 0.0106 Notes: 1.These resistance values are valid only For the parameters as given.Using conductors having coated strands,different .tranding type,and,especially,other temperatures changes the resistance. 2.Formula for temperature change: Ro=R, [l +(x(T,-75)] where(x,,,=0.00323,a,+,.=0.00330 at 75°C. 3.Conductors with compact and compressed stranding have about 9 percent and 3 percent.respectively,smaller bare conductor diameters than those shown. See Table 5A for actual compact cable dimensions. 4.The[ACS conductivities used: bare copper= I(x07r,aluminum=61I/r. 5,Class B stranding is listed as well as solid for some Sizes. Its overall diameter and area is that of its circumscribing circle. FPN: The construction information is per NEMA WC8- 1992 or ANSVUL 1581-2001. The resistance is calculated per National Bureau of Standards Handbook 100, dated 1966, and Handbook 109, dated 1972. 2008 Edition NATIONAL ELECTRICAL CODE 70-691 TABLES Table 9 Alternating-Current Resistance and Reactance for 600-Volt Cables, 3-Phase, 60 Hz, 75°C (167°F)-Three Single Conductors in Conduit Ohms to Neutral per Kilometer Ohms to Neutral per 1000 Feet Alternating-Current Resistance far Alternating-Current Effective Z at 0.85 PF Effective Z at 0.85 PF X1.(Reactance) Uncoated Resistance for for Uncoated Copper for Aluminum for All Wires Copper Wires Aluminum Wires Wires Wires Size PVC, Size (AWG Alumi- Alumi. Alumi- Alumi- Alum9- (AWG or num Steel PVC num Steel PVC nun Steel PVC num Steel PVC num Steel or kcmil) Conduits Conduit Conduit Conduit Conduit Conduit Conduit Conduit Conduit Conduit Conduit Conduit Conduit Conduit kemil) 14 0.190 0.240 10.2 10.2 10.2 - - - 8.9 8.9 8.9 - - - 14 0.058 0.073 3.1 3.1 3.1 - - - 2.7 2.7 2.7 - - 12 0.177 0.223 6.6 6.6 6.6 10.5 10.5 105 5.6 5.6 5.6 9.2 9.2 9.2 12 0.054 0.068 2.0 2.0 2.0 3.2 3.2 3.2 1.7 1.7 13 18 2.8 2.8 10 0.164 0.207 3.9 3.9 3.9 6.6 6.6 6.6 3.6 3.6 3.6 5.9 5.9 5.9 10 0.050 0.063 1.2 1.2 1.2 2.0 2.0 2.0 1.1 1.1 1.1 1.8 1.8 1.8 8 0.171 0.213 2.56 2.56 2.56 4.3 4.3 4.3 2.26 2.26 2.30 3.6 3.6 3.6 8 0.052 0.065 0.78 0.78 0.78 1.3 1.3 1.3 0.69 0.69 0.70 1.1 1.1 1.1 6 0.167 0.210 1.61 1.61 1.61 2.66 2.66 2.66 1.44 1.48 1.48 2.33 2.36 2.36 6 0.051 0.064 0.49 0.49 0.49 0.81 0.81 0.81 0.44 0.45 0.45 0.71 0.72 0.72 4 0.157 0.197 1.02 1.02 1.02 1.67 1.67 1.67 0.95 0.95 0.98 1.51 1.51 1.51 4 0.048 0.060 0.31 0.31 0.31 0.51 0.51 0.51 0.29 0.29 0.30 0.46 0.46 0.46 3 0.154 0.194 0.82 0.62 0.82 1.31 1.35 1.31 0.75 0.79 0.79 1.21 1.21 1.21 3 0.047 0.059 0.25 0.25 0.25 0.40 0.41 0.40 0.23 0.24 0.24 0.37 0.37 0.37 2 0.148 0.187 0.62 0.66 0.66 1.05 1.05 1.05 0.62 0.62 0.66 0.98 0.98 0.98 2 0.045 0.057 0.19 0.20 0.20 0.32 0.32 0.32 0.19 0.19 0.20 0.30 0.30 0.30 1 0.151 0.187 049 0.52 0.52 0.82 0.85 0.82 0.52 0.52 0.52 0.79 0.79 0.82 1 0.046 0.057 0.15 0.16 0.16 0.25 0.26 0.2.5 0.16 0.16 0.16 0.24 0.24 0.25 1/0 0.144 0.180 0.39 0.43 0.39 0.66 0.69 0.66 0.43 0.43 0.43 0.62 0.66 0.66 110 0.044 0.055 0.12 0.13 0.12 0.20 0.21 0.20 0.13 0.13 0.13 0.19 0.20 0.20 2/0 0.141 0.177 0.33 0.33 0.33 0.52 0.52 0.52 0.36 0.36 0.36 0.52 0.52 0.52 2/0 0.043 0.054 0.10 0.10 0.10 0.16 0.16 0.16 0.11 0.11 0.11 0.16 0.16 0.16 3/0 0.138 0.171 0.253 0.269 0,259 0.43 0.43 0.43 0.289 0.302 0.308 0.43 0.43 0.46 3/0 0.042 0.052 0.077 0.082 0.079 0.13 0.13 0.13 0.088 0.092 0.094 O.13 0.13 0.14 4/0 0.135 0.167 0.203 0.220 0.207 0.33 0.36 0.33 0.243 0.256 0.262 0.36 036 0.36 410 0.041 0.051 0.062 0.067 0.063 0.10 0.11 0.10 0.074 0.078 0.080 0.11 0.11 0.11 250 0.135 0.171 0.171 0.187 0,177 0.279 0.295 0.282 0.217 0.230 0.240 0.308 0.322 0.33 250 0.041 0.052 0.052 0,057 0.054 0.085 0.090 0.086 0.066 0.070 0.073 0.094 0.098 0.10 300 0.135 0.167 0.144 0.161 0.148 0.233 0.249 0.236 0.194 0.207 0.213 0.269 0.282 0.289 300 0.041 0.051 0.044 0.049 0.045 0.071 0.076 0.072 0.059 0.063 0.065 0.082 0.086 0,088 350 0.131 0.164 0.125 0.141 0.128 0.200 0.217 0.207 0.174 0.190 0.197 0.240 0.253 0.262 350 0.040 0.050 0.038 0,043 0.039 0.061 0.066 0.063 0.053 0.058 0.060 0.073 0.077 0.080 400 0.131 0.161 0.108 0.125 0.115 0.177 0.194 0.180 0.161 0.174 0.184 0.217 0.233 Q.24U 400 0.040 0.049 0.033 0.038 0.035 0.054 0.059 0.055 0.049 0.053 0.056 0.066 0.071 p.073 70-682 NATIONAL ELECTRICAL CODE 2008 Edition TABLES Table 9 Continued Ohms to Neutral per Kilometer Ohms to Neutral per IOW Feet Alternating-Current Resistance for Alternating-Current Effective Z at 0.85 PF Effective Z at 0.85 PF XL(Reactance) Uncoated Resistance for for Uncoated Copper for Aluminum for All Wires Copper Wires Aluminum Wires Wires Wires Size PVC, Size (AWG Alumi- Alumi- Alumi- Alumi- Alumi- (AWG or num Steel PVC num Steel PVC num Steel PVC Hum Steel PVC num Steel or kcmil) Conduits Conduit Conduit Conduit Conduit Conduit Conduit Conduit Conduit Conduit Conduit Conduit Conduit Conduit kemil) 500 0.128 0.157 0.089 0.105 0.095 0.141 0.157 O.i48 0.141 0.157 0.164 0.187 0.200 0.210 500 0.039 0.048 0.027 0.032 0.029 0.043 0.048 0.045 0.043 0.048 0.050 0.057 0.061 0.064 6W 0.128 0,157 0.075 0.(x92 0.082 0.118 0.135 0.125 0.131 0.144 0.154 0.167 0.180 0.190 600 UA39 0.048 0.023 0.028 0.[x15 0,036 0.041 0.038 0.040 0.044 0.047 0.051 0.055 0.058 750 0.125 0.157 0.062 0.079 0.069 0.095 0.112 0.102 0.118 0.131 0.141 0.148 0.161 0.171 750 0.038 0.048 0.019 0.024 0.021 0.029 (),()34 0.031 0.036 0.040 0.043 0.045 0.049 0.052 I000 0.121 0.151 0.040 0.062 0.059 0.075 0.089 0.082 0.105 0.118 0.131 0.128 0.138 0,151 1W0 0.037 0.046 0.015 0.019 0.018 0.023 0.027 0.025 0.032 0.036 0.040 0.039 0.042 0.046 Notes: 1.These values are based on the following constants: UL-Type RHH wires with Class B stranding, in cradled configuration.Wire conductivities are 100 percent IACS copper and 61 percent IACS aluminum,and aluminum conduit is 45 percent IACS. Capacitive reactance is ignored, since it is negligible at these voltages. These resistance values are valid only at 75°C (167°F) and for the parameters as given, but are representative for 6(10-volt wire types operating at 60 Hz. 2. t;.ffec•tive Z is defined as R cos(0) +X sin(B). where 0 is the power Factor angle of the circuit. Multiplying current by effective impedance gives a good approximation for line-to-neutral voltage drop.Effective impedance values shown in this table are valid only at 0.85 power Factor. For another circuit power factor(PF), effective impedance IZO can be calculated from R and X, values given in this table as follows: Ze = R x PF + Xr sinlarccos(PF)I. Tables 11(A) and 11(B) indicate the class of supply and its electrical rating.A Class For listing purposes, Table I I(A) and Table 11(13) pro- 2 power source not suitable for wet location use shall be so vide the required power source limitations for Class 2 and marked. Class 3 power sources. Table I I(A) applies for alternating- current sources, and Table 1 I(B) applies for direct-current Exception: Limited power circuits used by listed inforrna- sources. lion technology equipment. The power for Class 2 and Class 3 circuits shall be Overcurrent devices, where required, shall be located at either (1) inherently limited, requiring no overcurrent pro- the point where the conductor to be protected receives its tection, or (2) not inherently limited, requiring a combina- supply and shall not be interchangeable with devices of tion of power source and overcurrent protection. Power higher ratings.The overcurrent device shall be permitted as sources designed for interconnection shall be listed for the an integral part of the power source. purpose. As part of the listing, the Class 2 or Class 3 power source shall be durably marked where plainly visible to 200E Edition NATIONAL ELECTRICAL CODE 70-683 TABLES Table 11(A) Class 2 and Class 3 Alternating-Current Power Source Limitations Inherently Limited Power Source(Overcurrent Not Inherently Limited Power Source Protection Not Required) (Overcurrent Protection Required) Power Source Class 2 Class 3 Class 2 Class 3 Source voltage 0 through 20* Over 20 and Over 30 and Over 30 and 0 through Over 20 and Over 30 and Over 100 and Vmax(volts) (see Note 1) through 30* through 150 through 100 20* through 30* through 100 through 150 Power limitations — — — — 250(see 250 250 N.A. VA,,,.,,, (volt-amperes) Note 3) (see Note l) Current limitations 8.0 8.0 0.005 1501Vmax IOOOIV� 1000/V,x 1000/Vm,x 1.0 /max(amperes)(sce Note l I Maximum overcurrent — — — — 5.0 100 1Vmax 1001 Vmax 1.0 protection(amperes) Power source VA(volt- 5.0 x Vm„x 100 0.005 x Vmax 100 5.0 x V. l0O 100 100 maximum amperes) nameplate rating Current 5.0 1001Vmax 0.005 100/Vm„R 5.0 100/Vmax 100/V,ax IOO/Vmax (amperes) I T *Voltage ranges shown are for sinusoidal ae in indoor locations or where wet contact is not likely to occur. For nonsinusoidal or wet contact conditions,see Note 2. Table 11(B) Class 2 and Class 3 Direct-Current Power Source Limitations Inherently Limited Power Source(Overcurrent Not Inherently Limited Power Source Protection Not Required) (Overcurrent Protection Required) Power Source Class 2 Class 3 Class 2 Class 3 Source voltage 0 through Over 20 and Over 30 and Over 60 and Over 60 0 through Over 20 and Over 60 Over 100 Vmax(volts) 20* through 30* through 60* through 150 and 20' through 60* and and through (see Note l) through through 150 100 100 Power limitations — — — -- — 250(see 250 250 N.A. VA__ (volt-amperes) Note 3) (see Note 1) Current limitations 8.0 8.0 1501Vmax 0.005 1501V,,,ax 1000/Vmax 1000 1Vmax 10001Vmaa 1.0 Imax(amperes I (see Note 1) Maximum overcurrent --- — — — --- 5.0 [001Vm- 100/Vmax 1.0 protection(amperes) Power VA 5.0 x Vmax 100 100 0.005 x Vmax 100 5.0 x Vmax 100 100 100 source (volt-amperes) maximum nameplate Current 5.0 100/V,,,,,a 1001Vmax 0.005 100/V„„,x 5.0 1001v_ 100 1Vmax 1001V_ rating (amperes) *Voltage ranges shown are for continuous de in indoor locations or where wet contact is not likely to occur, For interrupted do or wet contact conditions,see Note 4. Notes for Tables 11(A)and 11(B) ].V_,Imaa, and VAmax are determined with the current-limiting impedance in the circuit(not bypassed)as follows: Vmax: Maximum output voltage regardless of load with rated input applied. I,,,ax:Maximum output current under any noncapacitive load,including short circuit,and with overcurrent protection bypassed if used.Where a transformer limits the output current,Imax limits apply after I minute of operation.Where a current-limiting impedance, listed for the purpose,or as part of a listed product,is used in combination with a nonpower-limited transformer or a stored energy source,e.g.,storage battery,to limit the output current,Imaxlimits apply after 5 seconds. VA,,,.,: Maximum volt-ampere output after i minute of operation regardless of load and overcurrent protection bypassed if used. 2. For nonsinusaida] ac, Vmax shall not be greater than 42.4 volts peak. Where wet contact(immersion not included) is likely to occur, Class 3 wiring methods shall be used or Vmax shall not be greater than 15 volts for sinusoidal ac and 21.2 volts peak for nonsinusoidal ac. 3. If the power source is a transformer, VA...is 350 or less when Vmax is 15 or less. 4. For do interrupted at a rate of 10 to 200 Hz, Vmax shall not be greater than 24.8 volts peak.Where wet contact(immersion not included)is likely to occur, Class 3 wiring methods shall be used,or Vmax shall not be greater than 30 volts for continuous dc; 12,4 volts peak for do that is interrupted at a rate of 10 to 200 Hz. 70-684 NATIONAL ELECTRICAL CODE 2008 Edition TABLES Tables 12(A) and 12(B) As part of the listing, the PLFA power source shall be For listing purposes, Tables 12(A) and 12(B) provide the durably marked where plainly visible to indicate that it is a required power source limitations for power-limited fire alarm power-limited fire alarm power source. The overcurrent de- sources. Table 12(A) applies for ahemating-current sources, vice, where required, shall be located at the point where the and Table 12(B) applies for direct-current sources. The conductor to be protected receives its supply and shall not be power for power-limited fire alarm circuits shall be either (1) interchangeable with devices of higher ratings. The overcur- inherently limited, requiring no overcurrent protection, or (2) rent device shall be permitted as an integral part of the power not inherently limited, requiring the power to be limited by a source. combination of power source and overcurrent protection. Table 12(A) PLFA Alternating-Current Power Source Limitations Inherently Limited Power Source Not Inherently Limited Power Source Power Source (Overcurrent Protection Not Required) (Overcurrent Protection Required) Circuit voltage 0 through 20 Over 20 and Over 30 and 0 through 20 Over 20 and Over 100 and V.,,(volts) (see Note 1) through 30 through 100 through 100 through 150 Power limitations — — — 250 250 N.A. VAm;,x(volt-amperes) (see Note 2) (see Note 1) Current limitations 8.0 8.0 1501Vm„x 1000/V,,,nx 1000/vn 1.0 lmuz (amperes) (see Note 1) Maximum overcurrent protection — — — 5.0 100/V.,' 1.0 (amperes) Power source VA(volt- 5.0 x V.,,, ]00 100 5.0 x Vn,ax 100 100 maximum amperes) nameplate ratings Current 5.0 1(H)/V_ 100/Vn,,,, 5.0 1001 V 100/Vmac (amperes) Table 12(B) PLFA Direct-Current Power Source Limitations Inherently Limited Power Source Not Inherently Limited Power Source Power Source (Overcurrent Protection Not Required) (Overcurrent Protection Required) Circuit voltage V__ (volts) 0 through 20 Over 20 and Over 30 and 0 through 20 Over 20 and Over 100 and (see Note 1) through 30 through 100 through 100 through 150 Power limitations VA... — — — 250 (see Note 2) 250 N.A. (volt-amperes) (see Note l) Current limitations 1,„,,,, (amperes) 8.0 8.0 150 1V—,,,, 1000/V mux 1000/Vm,x 1.0 (see Note I) Maximum overcurrent protection — — — 5.0 100/Vma: 1.0 (amperes) Power source VA(volt- 5.0 x V,n„x 100 100 5.0 x V,.,, 100 100 maximum amperes) nameplate ratings Current 5.0 100/V,,,,,x 100/V.,;,,, 5.0 100/Vman 100/Vmax (amperes) Notes For Tables 12(A) and 12(B) 1.V.—,I_.,and VA._are determined as follows: V,,,,,:Maximum output voltage regardless or load with rated input applied. 1,„;,,:Maximum output current under any noncapacitive load,including short circuit,and with overcurrent protection bypassed if used.Where a transformer limits the output current.Im„ limits apply after 1 minute of operation.Where a current-limiting impedance,listed for the purpose,is used in combination with a nonpower-limited transformer or a stored energy source,e.g., storage hanerv. to limit the output current,1,,,,,limits apply after 5 seconds. V.4,,,,,,: Maximum volt-ampere output after 1 minute of operation regardless of loud and overcurrent protection bypassed if used.Current limiting impedance shall not be bypassed when determining 1,,,;,,, and VA_,,. 2. If the power source is a transformer, VA.,,, is 350 or less when Vn,,,,,is 15 or less. 200H Edition NATIONAL ELECTRICAL CODE 70-685 Annex A: Product Standards ANNEX A Annex A Product Safety Standards Annex A is not a part of the requirements of this NFPA This annex does not form a mandatory part of the re- document but is included for informational purposes only. quirements of this Code but is intended only to provide This informational annex provides a list of product Code users with informational guidance about the product safety standards used for product listing where that listing characteristics about which Code requirements have been is required by this Code. It is recognized that this list is based. current at the time of publication but that new standards or modifications to existing standards can occur at any time while this edition of the Code is in effect. Product Standard Name Product Standard Number Antenna-Discharge Units UL 452 Arc-Fault Circuit-Interrupters UL 1699 Armored Cable UL 4 Attachment Plugs and Receptacles UL 498 Audio/Video and Musical Instrument Apparatus for Household,Commercial,and Similar General UL 60065 Use Audio-Video Products and Accessories UL 1492 Busways UL 857 Cables—Thermoplastic-Insulated Underground Feeder and Branch-Circuit Cables UL 493 Cables--Thermoplastic-Insulated Wires and Cables UL 83 Cables—Thermoset-Insulated Wires and Cables UL 44 Cable and Cable Fittings for Use in Hazardous(Classified)Locations UL 2225 Cables for Non-Power-Limited Fire-Alarm Circuits UL 1425 Cables for Power-Limited Fire-Alarm Circuits UL 1424 Capacitors UL 810 Cellular Metal Floor Raceways and Fillings UL 209 Circuit Integrity(CI)Cable—UL Outline of Investigation for Fire Tests for Electrical Circuit Subjet:t 1724 Protective Systems Circuit Integrity (CI)Cable—Tests of Fite Resistive Cables UL 21% Class 2 and Class 3 Transformers UL 1585 Class 2 Power Units UL 1310 Combustible Gas Detectors,Performance Requirements ISA 12.13.01 Commercial Audio Equipment UL 813 Communication Circuit Accessories UL 1863 Communications Cables UL 444 Community-Antenna Television Cables UL 1655 Conduit,Tubing,and Cable Fittings UL 514E Conduit--Type EB and A Rigid PVC Conduit and HDPE Conduit UL 651A Continuous Length HDPE Conduit UL 651B HDPE Control Centers for Changing Message Type Electric Signs UL 1433 Cord Sets and Power-Supply Cords UL 817 Cover P1ateS for Flush-Mounted Wiring Oeviees UL 514D data-Processing Cable UL 1690 Dead-Front Switchboards UL$91 Electric Motors UL 1004 Electric Sign Components UL 879 Electric Signs UL 48 Electric Spas.Equipment Assemblies, and Associated Equipment UL 1563 Electric Vehicle(EV) Charging System Equipment UL 2202 Electric Water Heaters for Pools and Tubs UL 1261 Electrical Apparatus for Explosive Gas Atmospheres —Part IL Intrinsic Safety"i" ISA 60079-11/UL 60079-11 Electrical Apparatus for Explosive Gas Atmospheres•—Part 15;Type of Protection"n" ISA 60079-15/UL 60079-I5 Electrical Apparatus for Use in Class I,Zone 1 Hazardous(Classified)Locations Type of ISA S12.23.011iiL 60079-18 Protection—Encapsulation"m" Electrical Apparatus for Use in Class I,Zones O& l Hazardous(Classified)Locations: General ISA 12,0.01IUL 60079-0 Requirements Electrical Apparatus for Use in Class I,Zone 1 Hazardous(Classified)Locations:Type of ISA S12.16.01/UL 60079-7 Protection--Increased Safety"e" Electrical Apparatus for Use in Class I,Zone 1 Hazardous(Classified)Locations:Type of ISA S12,22.011UL 60079-1 Protection—Flameproof"d" Electrical Apparatus for Use in Class I,Zone I Hazardous(Classified)Locations:Type of ISA S 12.25.011UL 60079.5 Protection—Powder Filling"q" Electrical Apparatus for Use in Class 1,Zone 1 Hazardous(Classified)Locations:Type of LSAS12.26.01/UL 60079-6 Protection--Oil-Immersion"O" Electrical Apparatus for Use in Tone 20,Zone 21,and Zone 22 Hazardous(Classified)Locations ISA 61241-18(12.10.07) —Protection by Encapsulation"MY' Electrical Apparatus for Use in Zone 20,Zone 21,and Zone 22 E3arardous(Classified)Locations ISA 61241-1 (12.10.03) Protection by Enclosure"td" 70-686 NATIONAL ELECTRICAL CODE; 2008 Edition ANNEX A Annex A: Product Standards Product Standard Name Product Standard Number Electrical Apparatus for Use in Zone 20,Zone 21,and Zone 22 Hazardous(Classified)Locations ISA 61241-0(12.10.02) —General Requirements Electrical Apparatus for Use in Zone 20,Zone 21,and Zone 22 Hazardous(Classified)Locations ISA 61241-11 (12.10.06) —Protection by Intrinsic Safety"iD" Electrical Apparatus for Use in Zone 21 and Zone 22 Hazardous(Classified)Locations-- ISA 61241-2(12.110.04) Protection by Pressurization"pD" Electrical Heating Appliances UL 499 Electrical Intermediate Metal Conduit—Steel UL 1242 Electrical Metallic Tubing—Aluminum UL 797A Electrical Metallic Tubing—Steel UL 797 Electrical Nonmetallic Tubing UL 1653 Electrical Rigid Metal Conduit—Steel UL 6 Electric-Battery-Powered industrial Trucks UL 583 Electromechanical Contactors and Motor Starters UL 60947-4-1 Emergency Lighting and Power Equipment UL 924 Enclosed and Dead-Front Switches UL 98 Enclosures for Electrical Equipment UL 50 Energy Management Equipment UL 916 Explosionproof and Dust-Ignition-Proof Electrical Equipment for Use in Hazardous(Classified) UL 1203 Loca6ots Fire Pump Controllers UL 218 Fire Resistive Cables UL 2196 Fixture Wire UL 66 Flame Propagation Height of Electrical and Optical-Fiber Cables Installed Vertically in Shafts UL 16M Flat-Plate Photovoltaic Modules and Panels UL 1703 Flexible Cords UL 62 Flexible Lighting Products UL 2388 Flexible Metal Conduit UL 1 Fluorescent-Lamp Ballasts UL 935 Gas and Vapor Detectors and Sensors UL 2075 Gas-Burning Hewing Appliances for Manufactured Homes and Recreational Vehicles UL 307B Gas-Fired Cooking Appliances for Recreational Vehicles UL 1075 Gas-Tuhc-Sign Cable UL 814 General-Use Snap Switches UL 20 Ground-Fault Circuit-Interrupters UL 943 Ground-Fault Sensing and Relaying Equipment UL 1053 Grounding and Bonding Equipment UL 467 Hardware for the Support of Conduit,Tubing and Cable UL 22.39 Heating and Cooling Equipment UL 1995 High-Intensity-Discharge Lamp Ballasts UL 1029 High Voltage Industrial Control Equipment UL 347 Household Refrigerators and Freezers UL 250 Industrial Battery Chargers UL 1564 Industrial Control Equipment UL 508 Industrial Control Panels UL 508A Instrumentation Tray Cable UL 2250 Insulated Wire Connector Systems for Underground Use or in Damp or Wet Locations UL 486D inverters,Converters,Controllers and Interconnection System Equipment for Use with Distributed UL 1741 Energy Resources Isolated Power Systems Equipment UL 1047 Junction Boxes for Swimming Pool Luminaires UL 1241 Liquid Fuel-Burning Heating Appliances for Manufactured Homes and Recreational Vehicles UL 307A Liquid-Tight Flexible Nonmetallic Conduit UL 1660 Liquid-Tight Flexible Steel Conduit UL 360 Lithium Batteries UL 1642 Low-Voltage Fuses—Part l: General Requirements UL 248-1 Low-Voltage Fuses— Part 2: Class C Fuses UL 248-2 Low-Voltage Fuses— Part 3: Class CA and CB Fuses UL 248-3 Low-Voltage Fuses—Part 4: Class CC Fuses UL 248-4 Low-Voltage Fuses—Part 5: Class G Fuses UL 248-5 Low-Voltage Fuses— Part 6: Class H Non-Renewable Fuses UL 248-6 Low-Voltage Fuses—Part 7: Class H Renewable Fuses UL 248-7 Low-Voltage Fuses—Part 8: Class J Fuses UL 248-8 Low-Voltage Fuses Part 9: Class K Fuses UL 248-9 Low-Voltage Fuses—Part 10: Class L Fuses UL 249-10 Low-Voltage Fuses—Part l I: Plug Fuses UL 248-11 Low-Voltage Fuses—Part 12: Class R Fuses UL 248-12 Low-Voltage Fuses— Part 13: Semiconductor Fuses UL 248-13 Low-Voltage Fuses—Part 14:Supplemental Fuses UL 248-14 Low-Voltage Fuses—Part 15:Class T Fuses UL 248-15 Low-Voltage Fuses--Part 16:Test Limiters UL 248-16 Low-Voltage Landscape Lighting Systems UL 1838 Low-Voltage Lighting Fixtures for Use in Recreational Vehicles UL 234 Low-Voltage LuminaireS UL 2108 Luminaire Reflector Kits for Installation on Previously Installed Fluorescent Luminaire- UL 1598 Supplemental Requirements Machine-Tool Wires and Cables UL 1003 2008 Edition NATIONAL ELECTRICAL CODE 70-687 Annex A: Product Standards ANNEX A Product Standard Name Product Standard Number Medical Electrical Equipment—Part l: General Requirements UL 60601-1 Medium-Voltage Power Cables UL 1072 Metal-Clad Cables UL 1569 Metal-Clad Cables and Cable-Sealing Fittings for Use in Hazardous(Classified)Locations UL 2225 Metallic Outlet Boxes UL 514A Mobile Home Pipe Heating Cable UL 1462 Molded-Case Circuit Breakers, Molded-Case Switches,and Circuit-Breaker Enclosures UL 489 Motor Control Centers UL 845 Motor-Operated Appliances UL 73 Neon Transformers and Power Supplies UL 2161 Nonincendive Electrical Equipment for Use in Class I and II, Division 2 and Class Ill,Divisions 1 ISA-12.12.01 and 2 Hazardous(Classified)Locations Nonmetallic Outlet Boxes, Flush-Device Boxes,and Covers UL 514C Nonmetallic Surface Raceways and Fittings UL 5A Nonmetallic Underground Conduit with Conductors UL 1990 Office Furnishings UL 1286 Optical Fiber Cable UL 1651 Optical Fiber and Communication Cable Raceway UL 2024 Panelboards UL 67 Performance Requirements,Combustible Gas Detectors ISA 12.13.01 Personal Protection Systems for Electric Vehicle Supply Circuits: UL 2231-1 General Requirements Personal Protection Systems for Electric Vehicle Supply Circuits: UL 2231-2 Particular Requirements for Protection Devices for Use in Charging Systems Plugs,Receptacles and Couplers for Electrical Vehicles UL 2251 Portable Electric Luminaires UL 153 Portable Power Distribution Units Ul 1640 Potting Compounds for Swimming Pool,Fountain,and Spa Equipment UL 676A Power Conversion Equipment UL 508C Power Outlets UL 231 Power Units Other Than Class 2 UL 1012 Power-Limited Circuit Cables UL 13 Professional Video and Audio Equipment UL 1419 Protectors for Coaxial Communications Circuits UL 497C Protectors for Data Communication and Fire Alarm Circuits UL 497B Protectors for Paired Conductor Communications Circuits UL 497 Reference Standard for Electrical Wires,Cables,and Flexible Cords UL 1581 Reinforced Thermosetting Resin Conduit(RTRC)and Fittings UL 1684 Residential Pipe Heating Cable UL 2049 Requirements for Process Sealing Between Electrical Systems and Potentially Flammable or ISA 12,27,01 Combustible Process Fluids Roof and Gutter De-Icing Cable Units UL 1588 Room Air Conditioners UL 484 Safety of Information Technology Equipment, Part 1:General Requirements UL 60950-1 Safety of I4forination Technology Equipment,Part 21:Remote Power Feeding UL 60950-21 Schedule 40 and 80 Rigid PVC Conduit and Fittings UL 651 Seasonal and Holiday Decorative Products UL 588 Secondary Protectors for Communications Circuits UL 497A Self-Ballasted Lamps and Lamp Adapters UL 1993 Service-Entrance Cables UL 854 Smoke Detectors for Fire Alarm Signaling Systems UL 268 Specialty Transformers UL 506 Splicing Wire Connectors UL 4860 Stage and Studio Lighting UL 1373 Standby Batteries UL 1989 Stationary Engine Generator Assemblies UL 2200 Strut-Type Channel Raceways and Fittings UL 5B Supplemental Requirements for Extra-Heavy Wall Reinforced Thermosetting Resin Conduit UL 1684A (RTRC)and Fittings Surface Metal Raceways and Fittings UL 5 Surface Raceways and Fittings for Use with Data,Signal and Control Circuits UL 5C Surge Arresters—Gapped Silicon-Carbide Surge Arresters for AC Power Circuits IEEE 062.1 Surge Arresters—Metal-Oxide Surge Arresters for AC Power Circuits IEEE 062.11 Swimming Pool Pumps, Filters, and Chlorinators UL 1081 Telephone Equipment UL 1459 Transfer Switch Equipment UL 1009 Transient Voltage Surge Suppressors UL 1449 Underfloor Raceways and Fittings UL 884 Underwater Luminaires and Submersible Junction Boxes UL 676 Uninterruplible Power Systems UL 1778 Vacuum Cleaners, Blower Cleaners,and Household Floor Finishing Machines UL 1017 Waste Disposers UL 430 Wire Connectors UL 486A-486B Wireways,Auxiliary Gutters,and Associated Fittings UL 870 70-6$8 NATIONAL ELECTRICAL CODE 2009 Edition ANNEX B Annex B:Ampacities Annex B Application Information for Ampacity Calculation This annex is not a part of the requirements of this NFPA the point of transition, a distance equal to 3 m (10 ft) or document but is included for informational purposes only. 10 percent of the circuit length figured at the higher ampac- ity, whichever is less. B.310.15(B)(1) Formula Application Information. This Where the burial depth of direct burial or electrical duct annex provides application information for ampacities cal- bank circuits are modified from the values shown in a fig- culated under engineering supervision. ure or table,ampacities can be modified as shown in(a)and (b) as follows. B.310.15(B)(2) Typical Applications Covered by Tables. Typical ampacities for conductors rated 0 through 2000 (a) Where burial depths are increased in part(s) of an electrical duct run to avoid underground obstructions, no volts are shown in Table 13.310.1 through Table 13.310.10. decrease in ampacity of the conductors is needed, provided Underground electrical duct bank configurations, as de- the total length of parts of the duct run increased in depth to tailed in Figure 13.310.3, Figure 13.310.4, and Figure avoid obstructions is less than 25 percent of the total run 13.310.5, are utilized for conductors rated 0 through 5000 length. volts. In Figure 13.310.2 through Figure 8.310.5, where ad- (b) Where burial depths are deeper than shown in a jacent duct banks are used, a separation of 1.5 m (5 ft) specific underground ampacity table or figure, an ampacity between the centerlines of the closest ducts in each bank or derating factor of 6 percent per increased 300 mm (foot) of 1.2 m (4 ft) between the extremities of the concrete enve- lopes is sufficient to prevent derating of the conductors due depth for all values of Rho can be utilized. No rating to mutual heating. These ampacities were calculated as de- change is needed where the burial depth is decreased. tailed in the basic ampacity paper,AIEE Paper 57-660, The B.310.15(B)(4) Electrical Ducts. The term electrical Calculation of the Temperature Rise and lead Capability duct(s) is defined in 310.60. of Cable Systems, by 1. H. Neher and M. H. McGrath. For additional information concerning the application of these B.310.15(B)(5) Tables B.310.6 and B.310.7. ampacities, see IEEEIICEA Standard S-1351P-46426, (a) To obtain the ampacity of cables installed in two Power Cable Ampacities, and IEEE Standard 835-1994, electrical ducts in one horizontal row with 190-mm (7.5-in.) Standard Power Cable Ampacity Tables. center-to-center spacing between electrical ducts, similar to Typical values of thermal resistivity (Rho) are as follows: Figure 13.310.2,Detail 1, multiply the ampacity shown for one Average soil (90 percent of USA) = 90 duct in Table B.310.6 and Table 13.310.7 by 0.88. Concrete = 55 (b) To obtain the ampacity of cables installed in four elec- Damp soil (coastal areas, high water table) = 60 trical ducts in one horizontal row with 190-mm (7.5-in.) Paper insulation = 550 center-to-center spacing between electrical ducts, similar to Polyethylene (PE) = 450 Figure 13.310.2, Detail 2, multiply the ampacity shown for Polyvinyl chloride (PVC) = 650 three electrical ducts in Table B.310.6 and Table B.310.7 by Rubber and rubber-like = 500 0.94. Very dry soil (rocky or sandy) = 120 Thermal resistivity, as used in this annex, refers to the B.310.15(B)(6) Electrical Ducts Used in Figure 13.310.2. heat transfer capability through a substance by conduction. If spacing between electrical ducts, as shown in Figure It is the reciprocal of thermal conductivity and is normally 13.310.2, is less than specified in Figure 13.310.2, where expressed in the units 'C-cm/watt. For additional informa- electrical ducts enter equipment enclosures from under- tion on determining soil thermal resistivity (Rho), see ground, the ampacity of conductors contained within such ANSMEEE Standard 442-1996, Guide for Soil Thennal electrical ducts need not be reduced. Resistivitv Measurements. B.310.15(B)(7) Examples Showing Use of Figure B.310.15(B)(3) Criteria Modifications. Where values of B.310.1 for Electrical Duct Bank Ampacity Modifica- load factor and Rho are known for a particular electrical tions. Figure B.310.1 is used for interpolation or extrapo- duct bank installation and they are different from those lation for values of Rho and load factor for cables installed shown in a specific table or figure, the ampacities shown in in electrical ducts. The upper family of curves shows the the table or figure can be modified by the application of variation in ampacity and Rho at unity load factor in terms factors derived from the use of Figure 13.310.1. of II, the ampacity for Rho=60,and 50 percent load factor. Where two different ampacities apply to adjacent por- Each curve is designated for a particular ratio All,, where tions of a circuit, the higher ampacity can be used beyond I. is the ampacity at Rho= 120 and 100 percent load factor, 2008 Edition NATIONAL ELECTRICAL CODE 70-689 Annex B:Ampacities ANNEX B The tower family of curves shows the relationship be- ampacity = 0.74 x 583 = 431, which agrees with the table tween Rho and load factor that will give substantially the for Rho = 90, LF= 100. same ampacity as the indicated value of Rho at 100 percent To determine the ampacity for the same circuit where load factor. Rho=80 and LF=75, using Figure 13.310.1, the equivalent As an example, to find the ampacity of a 500 kcmil Rho = 43, F = 0.855, and the desired ampacity = 0.855 copper cable circuit for six electrical ducts as shown in x 583 = 498 amperes_ Values for using Figure B.310A are Table 8.310.5:At the Rho=60, LF=50,h =583; for Rho found in the electrical duct bank ampacity tables of this annex. = 120 and LF = 100, 12 = 400. The ratio 12/1, = 0.686. Where the load factor is less than 100 percent and can Locate Rho = 90 at the bottom of the chart and follow the be verified by measurement or calculation, the ampacity of 90 Rho line to the intersection with 100 percent load factor electrical duct bank installations can be modified as shown. where the equivalent Rho = 90. Then follow the 90 Rho Different values of Rho can be accommodated in the same line to I2/1,ratio of 0.686 where F = 0.74. The desired manner. Table B.310.1 Ampacities of Two or Three Insulated Conductors, Rated 0 Through 2000 Volts, Within an Overall Covering (Multiconductor Cable), in Raceway in Free Air Based on Ambient Air Temperature of 30°C (86°F) Temperature Rating of Conductor. [See Table 310.13(A).] 60°C (140°F) 75°C (167°F) 90°C (194°F) 60°C (140°F) 75°C (167°F) 90°C (194°F) Types THHN, Types THHN, THHW, THHW, THW-2, THW-2, THWN-2, THWN-2, RHH, RHH, Types RHW, RWH-2, RWH-2, THHW, USE-2, Types RHW, USE-2, THW, XHHW, THHW, THW, XHHW, THWN, XHHW-2, THWN, XHHW-2, Types TW,OF XHHW, ZW ZW-2 Type TW XHHW ZW-2 Size (AWG or ALUMINUM OR COPPER-CLAD Size (AWG or kcmil) COPPER ALUMINUM kcmil) 14 16* 18* 21* — — — 14 12 20* 24* 27* 16* 18* 21* 12 10 27* 33* 36* 21* 25* 28* 10 8 36 43 48 28 33 37 8 6 48 58 65 38 45 51 6 4 66 79 89 51 61 69 4 3 76 90 t02 59 70 79 3 2 88 105 119 69 83 93 2 1 102 121 137 80 95 106 1 1/0 121 145 t63 94 113 127 110 2/0 138 166 186 108 129 146 210 310 158 189 214 124 147 167 3/0 410 187 223 253 147 176 197 410 250 205 245 276 160 192 217 250 300 234 281 317 185 221 250 300 350 255 305 345 202 242 273 350 400 274 328 371 218 261 295 400 500 315 378 427 254 303 342 500 70-690 NATIONAL,ELECTRICAL CODE 2009 Edition ANNEX B Annex B:Ampacities Table B.310.1 Continued Temperature Rating of Conductor. [See Table 310.13(A).] 60°C (140°F) 75°C (167°F) WC (194°F) 60°C (140°F) 75°C (167°F) 90°C (194°F) Types THHN, Types THHN, THHW, THHW, THW-2, THW-2, THWN-2, THWN-2, RHH, RHH, Types RHW, RWH-2, RWH-2, THHW, USE-2, Types RHW, USE-2, THW, XHHW, THHW, THW, XHHW, THWN, XHHW-2, THWN, XHHW-2, Types TW, OF XHHW, ZW ZW-2 Type TW XHHW ZW-2 Size(AWG or ALUMINUM OR COPPER-CLAD Size(AWG or kcmil) COPPER ALUMINUM kcmil) 600 343 413 468 279 335 378 600 700 376 452 514 310 371 420 700 750 387 466 529 321 384 435 750 800 397 479 543 331 397 450 800 900 415 500 570 350 421 477 900 1000 448 542 617 382 460 521 1000 Correction Factors Ambient For ambient temperatures other than 30°C ($6°F), multiply the ampacities shown above by the Ambient Temp. (°C) appropriate factor shown below. Temp. (°F) 21-25 1.08 1.05 1.04 1.08 1.05 1,04 70-77 26-30 1.00 1.00 1.00 1.00 1.00 1.00 79-86 31-35 0.91 0.94 0.96 0.91 0.94 0.96 88-95 36-40 0.82 0.88 0.91 0.82 0.88 0.91 97-104 41-45 0.71 0.82 0.87 0.71 0.82 0.87 106-113 46-50 0.58 0.75 0.82 0.58 0.75 0.82 115-122 51-55 0.41 0.67 0.76 041 0.67 0.76 124-131 56-60 - 0.58 0.71 - 0.58 0.71 133-140 61-70 - 0.33 0.58 -- 0.33 0.58 142-158 71-80 - - 0.41 - - 0.41 160-176 *Unless otherwise specifically permitted elsewhere in this Code, the overcurrent protection for these conductor types shall not exceed 15 amperes for 14 AWG,20 amperes for 12 AWG, and 30 amperes for 10 AWG copper; or 15 amperes for 12 AWG and 25 AWG amperes for 10 AWG aluminum and copper-clad aluminum. 2008 Edition NATIONAL.ELECTRICAL CODE 70-691 Annex B:Ampacities ANNEX 9 Table B.310.3 Ampacities or Multiconductor Cables with Not More Than Three Insulated Conductors, Rated 0 Through 2000 Volts, in Free Air Based on Ambient Air Temperature of 40°C (104°F) (For Types TC, MC, MI, UF, and USE Cables) Temperature Rating of Conductor. [See Table 310.13(A).] 60°C 75°C 85°C 90°C 60°C 75°C 85°C 90°C (140°F) (167°F) (185°F) (194°F) {140°F) (167°F) (185°F) (194°F) Size (AWG Size (AWG or kcmil) COPPER ALUMINUM OR COPPER-CLAD ALUMINUM or kemil) 18 -- - 1, - - - 18 16 - - 16* -- - 16 14 18* 21 24* 25* - - - - 14 12 21* 28* 30* 32* 21* 24* 25* 12 10 28* 36* 41* 43* 21* 28* 30* 32* 10 8 39 50 56 59 30 39 44 46 8 6 52 68 75 79 41 53 59 61 6 4 69 89 100 104 54 70 78 81 4 3 81 104 116 121 63 81 91 95 3 2 92 118 132 138 72 92 103 108 2 1 107 138 154 161 84 108 t20 126 1 1/0 124 160 178 186 97 125 139 145 1/0 210 143 184 206 215 111 144 160 168 210 310 165 213 238 249 129 166 185 194 310 4/0 190 245 274 287 149 192 214 224 410 250 212 274 305 320 166 214 239 250 250 300 237 306 341 357 186 240 268 280 300 350 261 337 377 394 205 265 296 309 350 400 281 363 406 425 222 287 317 334 400 500 321 416 465 487 255 330 368 385 500 600 354 459 513 538 284 368 410 429 600 700 387 502 562 589 306 405 462 473 700 750 404 523 586 615 328 424 473 495 750 800 415 539 604 633 339 439 490 513 800 900 438 570 639 670 362 469 514 548 900 1000 461 601 674 707 385 499 558 584 1000 Correction Factors Ambient For ambient temperatures other than 40°C (104°F), Ambient Temp. multiply the ampacities shown above Temp. (°C) by the appropriate factor shown below. (OF) 21-25 1.32 1.20 1.15 1.14 1.32 1.20 1.15 1.14 70-77 26-30 1.22 1.13 1.11 1.10 1.22 1.13 1.11 I.10 79-86 31-35 1.12 1.07 1.05 1.05 1.12 1.07 1.05 1.05 88-95 36-40 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 97--104 41-45 0.87 0.93 0.94 0.95 0.87 0.93 0.94 0.95 106-113 46-50 0.71 0.85 0.88 0.89 0.71 0.85 0.88 0.89 115-122 51-55 0.50 0.76 0.82 0.84 0.50 0.76 0.82 0.84 124-131 56-60 - 0.65 0.75 0.77 - 0.65 0.75 0.77 133-140 61-70 - 0.38 0.58 0.63 - 0.38 0.58 0.63 142-158 71-80 - - 0.33 0.44 - - 0.33 0.44 160-176 Unless otherwise specifically permitted elsewhere in this Cade, the overcurrent protection for these conductor types shall not exceed 15 amperes for 14 AWG,20 amperes for 12 AWG,and 30 amperes for 10 AWG copper, or 15 amperes for 12 AWG and 25 amperes for 10 AWG aluminum and copper-clad aluminum. 70-692 NATIONAL ELECTRICAL CODE 2008 Edition ANNEX 13 Annex B:Ampacities Table B.310.5 Ampacities of Single Insulated Conductors, Rated 0 through 2000 Volts, in Nonmagnetic Underground Electrical Ducts (One Conductor per Electrical Duct), Based on Ambient Earth Temperature of 20°C (68°F),Electrical Duct Arrangement per Figure B.310.2, Conductor Temperature 75°C (167°F) 3 Electrical Ducts 6 Electrical Ducts 9 Electrical Duels 3 Electrical Ducts 6 Electrical Ducts 9 Electrical Ducts (Fig.B.310.2, (Fig.B.310.2, (Fig.13.310.2, (Fig.B.310.2, (Fig. B.310.2, (Fig.B.310.2, Detail 2) Detail 3) Detail 4) Detail 2) Detail 3) Detail 4) Types RHW, Types RHW, Types RHW, Types RHW, Types RHW, 1Wpes RHW, THHW,THW, THHW,THW, THHW,THW, THHW,THW, THHW,THW, THHW,THW, THWN,XHHW, THWN,XHHW, THWN,XHHW, THWN,XHHW, THWN, XHHW, THWN,XHHW, USE USE USE USE USE USE Size Size (kcmil) COPPER ALUMINUM OR COPPER-CLAD ALUMINUM (kcmi4 RHO RHO RHO RHO RHO RHO RHO RHO RHO RHO RHO RHO RHO RHO RHO RHO RHO RHO 60 90 124 60 90 120 60 90 120 60 90 120 60 90 120 60 90 120 LF LF LF LF LF LF LF LF LF LF LF LF LF 1.17 LF LF LF LF 50 100 100 50 100 100 50 100 100 50 100 100 50 IOU 100 50 100 100 250 410 344 327 386 295 275 369 270 252 320 269 256 342 230 214 288 211 197 250 350 503 418 396 472 355 330 446 322 299 393 327 310 369 277 258 350 252 235 350 500 624 511 484 583 431 400 545 387 360 489 401 379 457 337 313 430 305 284 500 750 794 640 603 736 534 494 674 469 434 626 505 475 581 421 389 538 375 347 750 1000 936 745 700 864 617 570 776 533 493 744 593 557 687 491 453 629 432 399 1000 1250 1055 832 781 970 686 632 854 581 536 848 668 627 779 551 508 703 478 441 1250 1500 1160 907 849 1063 744 685 918 619 571 941 736 689 863 604 556 767 517 477 1500 1750 1250 970 907 1142 793 729 975 651 599 1026 796 745 937 651 598 823 550 507 1750 2000 1332 1027 959 1213 836 768 1030 683 628 1103 850 794 1005 693 636 877 581 535 2000 Ambient Ambient Temp. Correction Factors Temp. CC) (°F) 6-10 1.09 1.09 1.09 1.09 1.09 1.09 43-50 11-15 1.04 1.04 1.04 1.04 1.44 1.04 52-59 16-20 1.00 1.00 1.00 1.()0 1.00 1.00 61--68 21-25 0.95 4.95 0.95 0.95 0.95 0.95 70-77 26-30 0.90 0.90 0.90 0.90 0.90 0.90 79-86 2008 Edition NATIONAL EL6CMCAL COPE 70-693 Annex B:Ampacities ANNEX B Table B.310.6 Ampacities of Three Insulated Conductors, Rated 0 through 2000 Volts, Within an Overall Covering(Three-Conductor Cable) in Underground Electrical Ducts (One Cable per Electrical Duct) Based on Ambient Earth Temperature of 20°C (68°F), Electrical Duct Arrangement per Figure B.310.2, Conductor Temperature 75°C (167°F) 1 Electrical Duct 3 Electrical Ducts 6 Electrical Ducts 1 Electrical Duct 3 Electrical Ducts 6 Electrical Ducts (Fig.B310.2, (Fig.B.310.2, (Fig.B.310.2, (Fig.B.310.2, (Fig. 8.310.2, (Fig.B.310.2, Detail l) Detail 2) Detail 3) Detail l) Detail 2) Detail 3) Types RHW, Types RHW, Types RHW, Types RHW, Types RHW, Types RHW, THHW,THW, THHW,TRW, THHW,THW, THHW,THW, THHW,THW, THHW,THW, THWN,XHHW, THWN,XHH1Y, THWN,XHHW, THWN,XHHW, THWN, XHHW, THWN,XHHW, Size USE USE USE USE USE USE Size (AWG or (AWG or kcmil) COPPER ALUMINUM OR COPPER-CLAD ALUMINUM kcmil) RHO RHO RHO RHO RHO RHO RHO RHO RHO RHO RHO RHO RHO RHO RHO RHO RHO RHO 60 90 120 60 90 120 60 90 120 60 90 120 60 90 120 60 90 120 LF LF LF LF LF LF LF LF LF LF LF LF LF LF LF LF LF LF 50 100 100 50 100 100 50 100 100 50 100 100 50 100 100 50 100 100 8 58 54 53 56 48 46 53 42 39 45 42 41 43 37 36 41 32 30 8 6 77 71 69 74 63 60 70 54 51 60 55 54 57 49 47 54 42 39 6 4 101 93 91 96 81 77 91 69 65 78 72 71 75 63 60 71 54 51 4 2 132 121 118 126 105 100 119 89 83 103 94 92 98 82 78 92 70 65 2 1 154 140 136 146 121 114 137 102 95 120 109 106 114 94 89 107 79 74 1 110 177 160 156 168 137 130 157 116 107 138 125 122 131 107 101 122 90 84 110 210 203 183 178 192 156 147 179 131 121 158 143 139 150 122 115 140 102 95 210 310 233 210 204 221 178 158 205 148 137 182 164 159 172 I39 131 160 116 107 310 410 268 240 232 253 202 190 234 168 155 209 187 182 198 158 149 183 131 121 410 250 297 265 256 280 222 209 258 184 169 233 207 201 219 174 163 202 144 132 250 350 363 321 310 340 267 250 312 219 202 285 252 241 267 209 196 245 172 158 350 500 444 389 375 414 320 299 377 261 240 352 308 297 328 254 237 299 207 190 500 750 552 478 459 511 388 362 462 314 288 446 386 372 413 314 293 374 254 233 750 1000 628 539 518 1 579 435 405 522 351 321 521 447 430 480 361 336 433 291 266 1 1000 Ambient Ambient Temp. Correction Factors Temp. (°F) 6-10 1.09 1.09 1.09 1.09 1.09 1.09 43-50 11-15 1.04 1.04 1.04 1.04 1.04 1.04 52-59 16-20 1.00 1.00 1.00 1.00 1.00 1.00 6148 21-25 0.95 0.95 0.95 0.95 0.95 0.95 70-77 26-30 0.90 0.90 0.90 0.90 0.90 0.90 79--86 70--694 NATIONAL.ELECPRICAL CODE 2008 Edition ANNEX B Annex B:Ampacities Table B.310.7 Ampacities of Three Single Insulated Conductors, Rated 0 Through 2000 Volts, in Underground Electrical Ducts (Three Conductors per Electrical Duct) Based on Ambient Earth Temperature of 20°C (66°F), Electrical Duct Arrangement per Figure B.310.2, Conductor Temperature 75°C (167°F) 1 Electrical Duct 3 Electrical Ducts 6 Electrical Duels 1 Electrical Duct 3 Electrical Ducts 6 Electrical Ducts (Fig.B.310.2, (Fig.B.310.2, (Fig.8.310.2, (Fig.B310.2, (Fig. B.310.2, (Fig. B.310.2, Detail l) Detail 2) Detail 3) Detail l) Detail 2) Detail 3) Types RHW, Types RHW, Types RHW, Types RHW, Types RHW, Types RHW, THHW,THW, THHW,THW, THHW,THW, THHW,THW, THHW,THW, THHW,THW, THWN,XHHW, THWN,XHHW, THWN,XHHW, THWN,XHHW, THWN,XHHW, THWN,XHHW, Size USE USE USE USE USE USE Size (AWG or {AWG or kcmil) COPPER ALUMINUM OR COPPER-CLAD ALUMINUM kcmil) RHO RHO RHO RHO RHO RHO RHO RHO RHO RHO RHO RHO RHO RHO RHO RHO RHO RHO 60 90 120 60 90 120 60 90 120 60 90 120 60 90 120 60 90 120 LF LF LF LF LF LF LF LF LF LF LF LF LF LF LF LF LF LF 50 100 101 50 100 100 50 100 100 50 100 100 50 100 100 50 100 100 8 63 58 57 61 51 49 57 44 41 49 45 44 47 40 38 45 34 32 8 6 84 77 75 80 67 63 75 56 53 66 60 58 63 52 49 59 44 41 6 4 ill 100 98 105 86 81 98 73 67 86 78 76 79 67 63 77 57 52 4 3 129 H 6 113 122 99 94 113 83 77 101 91 89 83 77 73 84 65 60 3 2 147 132 128 139 112 106 129 93 86 115 103 100 108 87 82 101 73 67 2 1 171 153 148 161 128 121 149 106 98 133 119 115 126 100 94 116 83 77 1 110 197 175 169 185 146 137 170 121 111 153 136 132 144 114 107 133 94 87 IN 210 226 200 193 212 166 156 194 136 126 176 156 151 165 130 121 151 106 98 2A1 310 260 228 221) 243 189 177 222 154 142 203 178 172 189 147 138 173 121 ill 310 410 301 263 253 280 215 201 255 175 161 235 205 198 219 168 157 199 137 126 410 250 334 290 279 310 236 220 281 192 176 261 227 218 242 185 172 220 150 137 250 300 373 321 308 344 260 242 310 210 192 293 252 242 272 204 190 245 165 151 300 350 409 351 337 377 283 264 340 228 209 321 276 265 296 222 207 266 179 164 350 400 442 376 361 394 302 280 368 243 223 349 297 284 321 238 220 288 191 174 400 500 503 427 409 460 341 316 412 273 249 397 338 323 304 270 250 326 216 197 500 600 552 468 447 511 371 343 457 296 270 446 373 356 408 296 274 365 236 215 600 700 602 509 486 553 402 371 492 319 291 488 408 389 443 321 297 394 255 232 700 750 632 529 505 574 417 385 509 330 301 1 508 425 405 461 334 309 409 265 241 750 8DO 654 544 520 597 428 395 527 338 308 530 439 418 481 344 318 427 273 247 8W 900 692 575 549 628 450 415 554 355 323 563 466 444 510 365 337 450 288 261 9W 1000 730 605 576 1 659 472 435 1 581 372 338 597 494 471 1 538 385 355 475 304 276 1000 Ambient Ambient Temp. Correction Factors Temp. C (°F) 6-10 1.09 1.09 1.09 1.09 1.09 1.09 43-50 11--15 1.04 1.04 1.04 1.04 1.04 1.04 52-59 16-20 1.00 1.00 1.00 1.00 1.00 1.00 (11-68 21-25 0.95 0.95 0.95 0.95 0.95 0.95 70-77 26-30 0.90 0.90 0.90 0.90 0.90 0.90 79-86 2008 Edition NATIONAL ELECTRICAL COME 70-695 Annex B:Ampacities ANNEX B Table B.310.8 Ampacities of Two or Three Insulated Conductors, Rated 0 Through 2000 Volts, Cabled Within an Overall (Two- or Three-Conductor) Covering,Directly Buried in Earth, Based on Ambient Earth Temperature of 20°C (68°F),Arrangement per Figure B.310.2, 100 Percent Load Factor,Thermal Resistance(Rho) of 90 1 Cable (Fig. B.310.2, 2 Cables(Fig. B.310.2, 1 Cable (Fig. B.310.2, 2 Cables (Fig.B.310.2, Detail 5) Detail 6) Detail 5) Detail 6) 60°C 75°C 60°C 75°C 75°C 60°C 75-IC (167°F) (1(140°F) (167°F) (140°F) (167°F) (140 F (167°F) TYPES TYPES RHW, RHW, RHW, RHW, THHW, THHW, THHW, THHW, THW, THW, THW, THW, THWN, THWN, THWN, THWN, XHHW, XHHW, XHHW, i XHHW, OF USE OF USE OF USE I OF USE Size (AWG Size(AWG or kcmil) COPPER ALUMINUM OR COPPER-CLAD ALUMINUM or kcmil) 8 64 75 60 70 51 59 47 55 8 6 85 100 81 95 68 75 60 70 6 4 107 125 100 117 83 97 78 91 4 2 137 161 128 150 107 126 110 117 2 1 155 182 145 170 121 142 113 132 1 110 177 208 165 193 138 162 129 151 1/0 210 201 236 188 220 157 184 146 171 2/0 310 229 269 213 250 179 210 166 195 310 410 259 304 241 282 203 238 188 220 410 250 - 333 - 308 - 261 --- 241 250 350 - 401 - 370 - 315 - 290 350 500 - 481 - 442 - 381 -- 350 500 750 - 585 - 535 - 473 - 433 750 1000 - 657 - 600 - 545 - 497 1000 Ambient Ambient Temp. Correction Factors Temp. (°C) (°F) 6-10 1.12 1.09 1.12 1.09 1.12 1.09 1.12 1.09 43--50 11-15 1.06 1.04 1.06 1.04 1.06 1.04 1.06 1.04 52--59 16-20 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 61-68 21-25 0.94 0.95 094 0.95 0.94 0.95 0.94 0.95 70-77 26-30 0.87 0.90 0.87 0.90 0.87 0.90 0.87 0.90 79-86 Note: For ampacities of Type OF cable in underground electrical ducts, multiply the ampacities shown in the table by 0.74. 70-696 NATIONAL ELECTRICAL CODE 2008 Edition ANNEX B Annex B:Ampacities Table B.310.9 Ampacities of Three Triplexed Single Insulated Conductors, Rated 0 Through 2000 Volts, Directly Buried in Earth Based on Ambient Earth Temperature of 20°C (68°F),Arrangement per Figure B.310.2, 100 Percent Load Factor,Thermal Resistance (Rho) of 90 See Fig. B.310.2, See Fig. B.310.2, See Fig. B.310.2, See Fig.B.310.2, Detail 7 Detail 8 Detail 7 Detail 8 60°C 75°C 60°C 75°C 60°C 75°C 60°C 75°C (140°F) (167°F) (140°F) (167°F) (140°F) (167°F) (140°F) (167 0F) TYPES TYPES _T OF USE OF USE OF USE OF USE Size (AWG Size (AWG or kcmip COPPER ALUMINUM OR COPPER-CLAD ALUMINUM or kcmil) 8 72 84 66 77 55 65 51 60 8 6 91 107 84 99 72 84 66 77 6 4 119 139 109 128 92 108 85 100 4 2 153 179 140 164 119 139 109 I28 2 1 173 203 159 186 135 I58 124 145 1 110 197 231 181 212 154 I80 141 165 1/0 210 223 262 205 240 175 205 159 187 2/0 310 254 298 232 272 199 233 181 212 3/0 4/0 289 339 263 308 226 265 206 241 410 250 - 370 - 336 289 - 263 250 350 - 445 - 403 349 - 316 350 500 - 536 - 483 - 424 - 382 500 750 - 654 - 587 - 525 - 471 750 1000 - 744 - 665 - 608 - 544 1000 Ambient Ambient Temp. Correction Factors Temp. (OC) (°F) 6-10 1.12 1.09 1.12 1.09 1.12 1.09 1.12 1.09 43-50 11-15 1.06 1.04 1.06 1.04 1.06 1.04 1.06 1.04 52-59 16-20 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 61-68 21-25 0.94 0.95 0.94 0.95 0.94 0.95 0.94 0.95 70-77 26-30 0.87 0.90 0.87 0.90 0.87 0.90 0.87 0.90 79-86 2009 Edition NATIONAL ELECPRWAL CODE 711-697 Annex B:Ampacities ANNEX B Table B.310.10 Ampacities of Three Single Insulated Conductors, Rated 0 Through 2000 Volts, Directly Buried in Earth Based on Ambient Earth Temperature of 20°C (68 1F), Arrangement per Figure B.310.2, 100 Percent Load Factor, Thermal Resistance (Rho) of 90 See Fig. B.310.2, See Fig. B.310.2, See Fig.B.310.2, See Fig. B.310.2, Detail 9 Detail 10 Detail 9 Detail 10 60°C 75°C 60°C 75°C 60°C 75°C 60°C WC (140°F) (167°F) (140°F} (167°F) (140°F) (167°F) (140°F) (167°F) TYPES TYPES OF USE OF USE OF USE OF USE Size (AWG Size (AWG or kcmil) COPPER ALUMINUM OR COPPER-CLAD ALUMINUM or kcmil) 8 84 98 78 92 66 77 61 72 8 6 107 126 101 118 84 98 78 92 6 4 139 163 130 152 108 127 101 118 4 2 178 209 165 194 139 163 129 151 2 1 201 236 187 219 157 184 146 171 1 110 230 270 212 249 179 210 165 194 110 210 261 306 241 283 204 239 188 220 210 310 297 348 274 321 232 272 213 250 3/0 410 336 394 309 362 262 307 241 283 410 250 - 429 - 394 -- 335 - 308 250 350 - 516 - 474 - 403 - 370 350 500 626 - 572 - 490 - 448 500 750 767 - 700 - 605 - 552 750 1000 - 887 - 808 - 706 - 642 1000 1250 979 - 891 - 787 - 716 1250 1500 1063 - 965 - 862 - 783 1500 1750 - 1133 - 1027 - 930 - 843 1750 2000 - 1195 - 1082 - 990 -- 897 2000 Ambient Ambient Temp. Correction Factors Temp. (°C) (°F) 6-10 1.12 1.09 1.12 1.09 1.12 1.09 1.12 1.09 43-50 11-15 1.06 1.04 1.06 1.04 1.06 1.04 1.06 1.04 52-59 16-20 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 61-68 21-25 0.94 0.95 0.94 0.95 0.94 0.95 0.94 0.95 70-77 26-30 0.87 0.90 0.87 0.90 0.87 0.90 0.87 0.90 79-86 70-698 NATIONAL ELECTRICAL CODE. 2008 Edition ANNEX B Annex B:Ampacities 115 1.10 1.05 1.00 0.95 — a a5 0.90 a 0.65 1155 `�� a 1 0.75 0 0.70 0 75 0.65 711 0.60 a 055 a' 050 oss 045 a 5p 040 10 20 30 40 50 60 70 80 90 100110 12O M140 150 160170 180 1 90 200 100 95 90 - 85 � 80 75 0 70 — m � 65 \ I v 60 1-- - 55 5o 45 — 40 - — ti 35 30 0 10 20 30 40 50 6 70 80 90 100 110 120 130140 150160 170 1 BO 190 200 RHO Figure B.310.1 Interpolation Chart for Cables in a Duct Bank 11 =ampacity for Rho= 60,50 LF; 12= ampacity for Rho = 120, 100 LF( load factor); desired ampacity = F x Ii. 2008 Edition NATIONAL ELECTRICAL CODE 70-699 Annex B:Ampacities ANNEX B w '^ O O E v O•. v E.E 5 V o 0 Detail 1* o E O O 290 mm x 290 mm -- °' E 9 ° ° E Z (11.5 in.x 11.5 In.) 190 mm(7.5 In.) o LO o u, Electrical duel bank m r-: a O rz One electrical duct Mail 2 T v v a 475 mm x 475 mm (19 in.x 19 in.) Electrical duct bank 190 mm(7.5 in.) 190 mm 190 mm Three electrical ducts Detail 3 (7.5 in.) (7.5 in.) or 475 mm x 675 mm Detall 4 0 9 in.x 27 in.) 675 mm x 675 mm v a Electrical duct bank (27 In.x 27 in.) Q v Six electrical ducts Electrical duct bank or Nine electrical ducts 190 mm 190 mm (7,5 in.) (7.5 in.) E^ E c X 675 mm x 290 mm ovi I ov o (27 in.x11.5in.) Electrical duct bank Three electrical ducts 190 mm 190 mm (7.5 in.) (7.5 in.) 675 mm x 475 mm (27 in.x 19 in.) Electrical duct bank 600 mm 600 mm _ (24 in.) (24 in.) Detail 5 Detail 6 Detail 7 Detall a Buried 3 Buried 3 Buried triplexed Buried triplexed conductor conductor cables(1 circuit) cables(2 circuits) cable cables 190 mm 190 mm 190 mm 190 mm 190 mm 190 mm (7.5 in.) (7.5 in.) (7.5 in.) (7.5 in.) 600 mm (7.5 in.) (7.5 in.) • • • �� (24 in.) Detail 9 Detail 10 Buried single-conductor Buried single-conductor cables(1 circuit) cables(2 circuits) Note 1:Minimum burial depths to lop electrical ducts or cables shall be in Legend accordance with 300.5. Maximum depth to the top of electrical duct Backfill banks shall be 750 mm(30 in.)and maximum depth to the lop of 0 (earth or concrete) direct buried cables shall be 900 mm(36 in.) Q Electrical duct Note 2:For two and four electrical duct installations with electrical ducts installed in a single row,see B.310.15(13)(5). • Cable or cables Figure B.310.2 Cable Installation Dimensions for Use with Table B.310.5 Through Table B.310.10. 70-700 NATIONAL F,LE(_TRICAL CODE 2008 Edition ANNEX B Annex B.Ampacities Surface Surface 150 mm(6 in,) 150 mm 6 in. N and D 150 mm (6 in,) N and v o d a a 150 mm(6 in.) EGC EGC p a 600 mm(24 in,)+ OO O AO 190 mm(7.5 in.) r , O ' pO, O O - O O O 750 mm(30 in.) 250 mm(10 in,) . V n ' , Oo O OOr 950 mm(38 in.) 190 mm(7,5 in.) B0 tr 250 mm(10 o 190 mm 190 mm {6r aicai (7.5 in.) (7.5 in.) 250 mm 250 mm 250 mm F 675 mm(27 in.) (10 in,) (10 in.) (10 in.) 11 m(44 in.) Design Criteria Number of Cables per Phase=9 Neutral and Equipment Rho concrete=Rho Earth 5 Grounding conductor(EGC) Design Criteria Number of Cables per Phase=4 Duct=150 mm(6 in.) Rho PVC Duct =650 Neutral and Equipment Rho Concrete=Rho Earth-5 Phase Ducts=75 10 125 mm(3 l0 5 in.) Rho Cable Insulation=500 Duct=Grounding Conductor(EGC} Rho PVC Duct=650 Conductor Malarial=Copper Rho Cable Jacket=650 Duct=150 mm(6 m.} Phase Ducts=75 mm(3 m.) Rho Cable Insulation=500 Number of Cables per Duct=3 Conductor Malarial=Copper Rho Cable Jacket=650 Notes: Number of Cables per Duct=1 1 Neutral conriguration per 300.5(1),Exception No.2,for isolated phase installations in Notes: nonmagnetic ducts. 1. Neutral configuration per 300.5(q,Exception No.2. 2.Phasing is A,B,C in rows or columns.Where magnetic electrical ducts are used, 2, Maximum harmonic loading on the neutral conductor cannot exceed 50 percent of the conductors are installed A,B.C per electrical duct with the neutral and all equipment grounding conductors m the same electrical duct. In [his case, the 6-in. phase current for the a MV- 0 c shown in the gable. trade size neutral duct is eliminated. 3. Metallic shields of Type MV-90 cable shalt he grounded at one point only. 3.Maximum harmonic loading on the neutral conductor cannel exceed 50 percent of the phase current for the ampacilies shown in the table. 4.Metallic shields of Type MV-90 cable shall be grounded at one point only where using TYPES A,B,C phasing in rows or columns RHW,THHW,THW,THWN, Size XHHW,USE,OR MV-90" Size kcmp Total kcmll TYPES per Phase Ampere Rating RHW,THHW,THW,THWN, RHO EARTH 60 RHO EARTH 90 RHO EARTH 120 Size XHHW,USE,OR MV-90' Size LF 50 LF 100 LF log kcmll Total per Phase Ampere Rating kcmll 2820 1860 1680 750 (705KCable) (465AICable) (420AICable) 750 RHO EARTH 60 RHO EARTH 90 RHO EARTH 120 3300 2140 1920 LF 50 LF 100 LF 100 1000 (825A/Cable) (535AICabfe) (480AICable) 1000 2340 Ism 1395 3700 2360 2120 250 (260AlCable) (170AlCable) 055AICable) 250 1250 (925A(Cabte) (595AJCable) I (530AlCaNe) 1250 2790 1800 1665 4066 2580 2300 350 (310AiCable) (200A1Cable) {185A/Cable) 350 1500 �(1()115VCabla) (645AJCable) (575AICabla) 1500 3375 2160 1980 4360 2740 2460 500 (375AICable) (240AlCable) (220AtCable) 500 1750 090A1Ca61e) (665A/Cablo) (615A/Cable) 1750 Ambient For ambient temperatures other than 20°C(86'F), Ambient Ambient For ambient temperatures other than 20°C(6WF), Ambient Temp. multiply the ampacitles shown above by the Temp. Tem p. mulllpty the ampacities shown above by the Temp. (°C) appropriate lector shown below. (°F) (°C) appropriate factor shown below. (°F) 6-10 1.09 1.p9 1.09 109 1109 43-50 6-10 1.09 1.09 1.09 1.09 1.09 43 50 11-15 104 1.04 1.04 1.04 1.04 52-59 11-15 1.04 1.114 1.04 104 1.114 52-59 16-20 1.00 1.00 1.00 1.00 1.00 61-69 16-20 1.00 1.00 1.00 1.00 . 1.00 61-66 21-25 0.95 0.95 0.95 6.95 0.95 70-77 21-25 0.95 0.95 0.95 0.95 0.95 70-77 26-30 0.90 0.90 0.90 090 0.90 79-66 26-30 0.90 0.90 0.90 0.90 0.90 79-86 'Limited Ia 75°C conductor temperature. 'Limited to 75°C conductor temperature FPN Figure B.310.3 Ampacities of Single Insulated Conductors FPN Figure B.310.4 Ampacities of Single Insulated Conductors Rated 0 through 5000 Volts in Underground Electrical Ducts Rated 0 through 5000 Volts in Nonmagnetic Underground Elec- (Three Conductors per Electrical Duct),Nine Single-Conductor trical Ducts (One Conductor per Electrical Duct), Four Single- Cables per Phase Based on Ambient Earth Temperature of 20°C Conductor Cables per Phase Based on Ambient Earth Tempera- (68 0F), Conductor Temperature 75°C(167°F� ture of 20°C(68°F),Conductor Temperature 75eC(167°F). 2008 Edition NATIONAL ELECTRICAL CODE 70-701 Annex B:Ampacities ANNEX B Surface Table B.310.11 Adjustment Factors for More Than Three Current-Carrying Conductors in a Raceway or Cable with 150 mm 6 in. Load Diversity N and A d D v e D , Q 150 mm{6 in.) EGC D n Percent of Values in Tables as D D ° D 600 mm(24 in.) Number of Current- Adjusted for Ambient AO � u O O O vO Oq _ Carrying Conductors Temperature if Necessary 250 mm(10 in.) v ' ° Q ' 4—6 80 B 0 D 850 mm(38 in.) 7—9 70 250 mm(10 in.) D ° ° ° ° D 10-24 70*25 -42 60* co — D O OD O oO. O ti 43 — 85 0* 250 mm 250 mm 250 mm 250 mm *These factors include the effects of a load diversity of 50 percent. (10 in.) (10 in.) (loin. (10 in.) FPN: The ampacity limit for the number of current- .., m(44 in.) carrying conductors in 10 through 85 is based on the fol- lowing formula. For greater than 85 conductors, special Neutral Criteria Equipment Number cr Cables per Phase=5 calculations are required that are beyond the scope of this Neutral and Equipment Rho Concrete=Rho Earth-5 q Y p Grounding Conductor(EGC) Rho PVC Duct=650 table. Duct=154 mm(6 in.) Phase Ducts=75 mm(3 in.) Rho Cable Insulation=500 Conductor Material=Copper Rho Cable Jacket=650 F105N Number of Cables per Duct=1 �t2= I } or A,,whichever is less Notes, 1. Neutral conligurabon per 300 5(0,Exception No.2. 2. Maximum harmonic loading on the neutral conductor cannot exceed 50 percent of the phase current for the ampagdies shown in the table. 3 Metallic shields of Type MV-90 cable shall be grounded alone point only where: A I = ampacity from Table 310.16; Table 310.18; TYPES Table B.310.1; Table 13.310.6; and Table RHW,THHW,THW,THWN, Size XHHW,USE,OR MV-90• Size 13.310.7 multiplied by the appropriate factor kemll Total per Phase Ampere Rating kamll from Table B.310.11. RHO EAFrrH 60 RHO EARTH 00 RHO EARTH 120 N = total number of conductors used to obtain LF 50 LF 100 LF 100 m multi P 1 Y g factor from Table B.310.11 2000 (1115AICable) (675A Cable) (600 CA( ble) 2000 E = desired number of current-carrying conductors Ambient For ambient temperatures other than 20'C(BB°F), Ambient in the raceway or cable Temp, multiply the ampacities shown above by the Temp. A2 = ampacity limit for the current-carrying (°C) appropriate Factor shown below. (19 conductors in the raceway or cable 6-10 1.09 1.09 1,09 1.09 1.09 43-50 11-15 1.04 1.04 1 04 1 D4 1.04 52-59 16-20 1.00 1.00 1.00 1.00 1.00 61_6 Example 1 21-25 0.95 0.95 0.95 095 095 70-17 26-30 0.90 0.90 0.90 0.90 0-90 79-86 Calculate the ampacity limit for twelve 14 AWG 'Limited to 75°C conductor temperature. THWN current-carrying conductors (75°C) in a raceway that contains 24 conductors. F PN Figure B.310.5 Ampacities of Single Insulated Conductors Rated 0 through 5000 Volts in Nonmagnetic Underground Elec- (0 5}(24) trical Ducts (One Conductor per Electrical Duct), Five Single- I_'= 12 x20(0.7} Conductor Cables per Phase Based on Ambient Earth Tempera- ture of 20°C (68°Y),Conductor Temperature 75°C (167°F). = 14 amperes (i.e.,50 percent diversity) Example 2 Calculate the ampacity limit for eighteen 14 AWG THWN current-carrying conductors (75°C) in a raceway that contains 24 conductors. (0.5)(24) A, 1R x20(0.7)=11.5 amperes 70-702 NATIONAL ELECTRICAL CODE 2008 Edition ANNEX C Annex C: Tables Annex C Conduit and Tubing Fill Tables for Conductors and Fixture Wires of the Same Size This annex is not a part of the requirements of this NFPA document but is included far informational purposes only. Table Page C.1 — Electrical Metallic Tubing (EMT) 704 C.I(A)* —Electrical Metallic Tubing (EMT) 708 C.2—Electrical Nonmetallic Tubing (ENT) 709 C.2(A)*—Electrical Nonmetallic Tubing (ENT) 713 C.3 —Flexible Metal Conduit (FMC) 714 C.3(A)* —Flexible Metal Conduit (FMC) 718 CA— Intermediate Metal Conduit (IMC) 719 C.4(A)* ---Intermediate Metal Conduit (IMC) 723 C.5 —Liquidtight Flexible Nonmetallic Conduit (Type LFNC-B) 724 C.5(A)* —Liquidtight Flexible Nonmetallic Conduit (Type LFNC-B) 728 C.6— Liquidtight Flexible Nonmetallic Conduit (Type LFNC-A) 729 C.6(A)* —Liquidtight Flexible Nonmetallic Conduit (Type LFNC-A) 733 C.7— Liquidtight Flexible Metal Conduit (LFMC) 734 C.7(A)* —Liquidtight Flexible Metal Conduit(LFMC) 738 C.8— Rigid Metal Conduit (RMC) 739 C,8(A)* — Rigid Metal Conduit(RMC) 743 C.9—Rigid PVC Conduit, Schedule 80 744 C.9(A)*— Rigid PVC Conduit, Schedule 80 746 C.10— Rigid PVC Conduit, Schedule 40 and HDPE Conduit 749 C.10(A)* —Rigid PVC Conduit, Schedule 40 and HDPE Conduit 753 C.I I —Type A, Rigid PVC Conduit 754 C.I I(A)* —Type A, Rigid PVC Conduit 758 C.12--Type EB, PVC Conduit 759 C.12(A)*—Type EB, PVC Conduit 762 *Where this table is used in conjunction with Tables C.I through C.12,the conductors installed must be of the compact type. 2008 Edition NATIONAL ELECTRICAL CODE 70-703 Annex C: 'Fables ANNEX C Table C.1 Maximum Number of Conductors or Fixture Wires in Electrical Metallic Tubing (EMT) (Based on Table 1, Chapter 9) CONDUCTORS Conductor Metric Designator(Trade Size) Size (AWG 16 21 27 35 41 53 63 78 91 103 Type kcmil) ('/z) (•%a) (1) (1114) (1'/2) (2) (2'/z) (3) (3'/2) (4) RHH, 14 4 7 II 20 27 46 80 120 157 201 RHW, 12 3 6 9 17 23 38 66 100 131 167 RHW-2 10 2 5 8 13 18 30 53 81 105 135 8 1 2 4 7 9 16 28 42 55 70 6 1 1 3 5 8 13 22 34 44 56 4 1 1 2 4 6 10 17 26 34 44 3 1 1 l 4 5 9 15 23 30 38 2 1 1 l 3 4 7 13 20 26 33 1 0 1 1 l 3 5 9 13 17 22 1/0 0 1 1 l 2 4 7 11 15 19 210 0 1 1 1 2 4 6 10 13 17 310 0 0 1 1 1 3 5 8 11 14 410 0 I) 1 1 1 3 5 7 9 12 250 0 1) 0 1 1 1 3 5 7 9 3(H) 0 0 0 1 1 1 3 5 6 8 350 0 0 0 1 1 3 4 6 7 400 0 0 0 1 1 1 2 4 5 7 500 0 () 0 0 1 1 2 3 4 6 600 0 0 0 () 1 1 1 3 4 5 7W (1 l) l) 0 O 1 1 2 3 4 750 0 0 0 l) 0 1 1 2 3 4 800 0 0 0 0 l) 1 1 2 3 4 900 0 0 0 0 0 1 1 1 3 3 1000 0 0 0 0 0 1 1 1 2 3 1250 0 0 0 0 0 0 1 1 1 2 1500 0 0 0 0 0 0 l 1 1 1 1750 0 0 0 0 0 0 l 1 1 1 20(x) 0 0 U 0 0 0 1 1 1 1 TW l4 8 15 25 43 58 96 168 254 332 424 12 6 11 19 33 45 74 129 195 255 326 10 5 8 14 24 33 55 96 145 190 243 8 2 5 8 13 18 30 53 81 105 135 RHH*, 14 6 10 16 28 39 64 112 169 221 282 RHW*, RHW-2*, THHW, TH W, TH W-2 RHH*, 12 4 8 13 23 31 51 90 136 177 227 RHW'. RHW-2*, 1 0 3 6 10 18 24 40 70 106 138 177 THHW. TH W RHH*, 8 1 4 6 10 14 24 42 63 83 106 RHW*, RHW-2*, THHW. TH W, THW-2 70--704 NATIONAL ELECTRICAL CODE 2008 Edition ANNEX C Annex C: Tables Table CA Continued CONDUCTORS Conductor Metric Designator(Trade Size) Size (AWG 16 21 27 35 41 53 63 78 91 103 Type kemil) (s/z) ('/a) (1) (1'14) (l'h) (2) (21/2) (3) (31/2) (4) RHH*, 6 1 3 4 8 11 18 32 48 63 81 RHW*. 4 1 1 3 6 8 13 24 36 47 60 RHW-2*, 3 1 1 3 5 7 12 20 31 40 52 TW, 2 1 1 2 4 6 10 17 26 34 44 TH W, I 1 1 1 3 4 7 12 18 24 31 THH W, 110 0 1 1 2 3 6 10 16 20 26 TH W-2 210 0 1 1 1 3 5 9 13 17 22 3/0 0 1 1 1 2 4 7 11 15 19 4/0 0 0 1 1 1 3 6 9 12 16 250 0 0 1 1 1 3 5 7 10 13 300 0 0 1 1 1 2 4 6 8 350 0 0 0 1 l 1 4 6 7 10 400 0 0 0 1 l 1 3 5 7 9 500 0 0 0 1 l 1 3 4 6 7 600 0 0 0 1 l 1 2 3 4 6 700 0 0 0 0 l 1 1 3 4 5 750 0 0 0 0 l 1 l 3 4 5 80() 0 U 0 0 1 1 l 3 3 5 900 0 0 0 0 0 1 l 2 3 4 1000 0 0 0 0 0 1 l 2 3 4 1250 0 0 0 0 0 1 l 1 2 3 1500 0 0 0 0 0 1 l 1 1 2 1750 0 0 0 0 0 0 l 1 1 2 2000 (1 0 0 0 0 0 1 1 1 THHN, 14 12 22 35 61 84 138 241 364 476 608 THWN, 12 9 16 26 45 61 101 176 266 347 443 THWN-2 10 5 10 16 28 38 63 111 167 219 279 8 3 6 9 16 22 36 64 96 126 161 6 2 4 12 16 26 46 69 91 116 4 1 2 4 7 10 16 28 43 56 71 3 1 1 3 6 8 13 24 36 47 60 2 1 1 3 5 7 11 20 30 40 51 l l 1 1 4 5 8 15 22 29 37 110 l 1 1 3 4 7 12 19 25 32 210 0 1 1 2 3 6 10 16 20 26 310 0 1 1 1 3 5 8 13 17 22 410 0 1 1 l 2 4 7 11 14 18 250 0 0 1 l 1 3 6 9 11 15 3W 0 0 1 l 1 3 5 7 10 13 350 0 0 1 l 1 2 4 6 9 11 400 0 0 0 l 1 l 4 6 8 10 500 0 0 0 l 1 l 3 5 6 8 600 0 0 0 1 1 l 2 4 5 7 700 0 0 0 l 1 l 2 3 4 6 750 0 0 0 0 1 l 1 3 4 5 800 0 0 0 0 1 l 1 3 4 5 900 0 0 0 0 1 l 1 3 3 4 1000 0 0 0 0 1 1 1 2 3 4 FEP, 14 12 21 34 60 81 134 234 354 462 590 FEPB, 12 9 15 25 43 59 98 171 258 337 430 PFA, l0 6 11 18 31 42 70 122 185 241 309 PFA H, 8 3 6 10 18 24 40 70 106 138 177 TFE 6 2 4 7 12 17 28 50 75 98 126 4 3 5 9 12 20 35 53 69 88 3 2 4 7 10 16 29 44 57 73 2 1 3 6 8 13 24 36 47 60 (Canlinues) 2008 Edition NATIONAL ELECTRICAL CODE 70-705 Annex C: Tables ANNEX C Table C.I. Continued CONDUCTORS Conductor Metric Designator(Trade Size) Size (AWG 16 21 27 35 41 53 63 78 91 103 Type kemil) ('/z) {1/a) (1) (1'14) (1 VI) (2) (2112) (3) (31h) (4) PFA, 1 1 1 2 4 6 9 16 25 33 42 PFAH, TFE PFAH, 110 1 1 l 3 5 8 14 21 27 35 TFE PFA. 210 0 1 l 3 4 6 11 17 22 29 PFAH, 310 O 1 l 2 3 5 9 14 18 74 TFE.Z 410 0 1 l l 2 4 8 11 15 19 Z 14 14 25 41 72 98 161 282 426 556 711 12 10 18 29 51 69 114 200 302 394 504 10 6 11 18 31 42 70 122 185 241 309 8 4 7 11 20 27 44 77 117 153 195 6 3 5 8 14 19 31 54 82 107 137 4 1 3 5 9 13 21 37 56 74 94 3 1 2 4 7 9 15 27 41 54 69 2 1 1 3 6 8 13 22 34 45 57 ] 1 1 2 4 6 10 18 28 36 46 XHH, 14 8 15 25 43 58 96 168 254 332 424 XHHW, 12 6 11 19 33 45 74 129 195 255 326 XHHW-2, 10 5 8 14 24 33 55 96 145 190 243 Zw 8 2 5 8 13 18 30 53 81 105 135 6 1 3 6 10 14 22 39 60 78 100 4 1 2 4 7 10 16 28 43 56 72 3 1 1 3 6 8 14 24 36 48 61 2 1 1 3 5 7 Il 20 31 40 51 XHH, I 1 1 1 4 5 8 15 23 30 38 XHHW, 110 1 1 1 3 4 7 13 19 25 32 XHHW-2 210 {} 1 1 2 3 6 10 16 21 27 310 0 1 1 1 3 5 9 13 17 22 410 0 1 1 1 2 4 7 11 14 18 250 {} 0 1 1 1 3 6 9 12 15 300 I) 1) 1 1 1 3 5 8 10 13 350 f) 0 1 1 1 2 4 7 9 11 400 0 0 0 1 1 1 4 6 8 10 500 0 0 0 1 1 1 3 5 6 8 600 0 {} 0 1 1 1 2 4 6 700 0 0 0 0 1 l 2 3 4 6 750 I) 0 0 0 l 1 l 3 4 5 800 i) 1) 0 0 1 1 1 3 4 5 900 {} 1) () 0 1 l 1 3 3 4 1000 0 0 0 0 0 l 1 2 3 4 1250 0 0 0 0 0 l 1 1 2 3 1500 0 0 0 0 0 l 1 1 l 3 1750 0 0 0 0 0 0 1 1 l 2 20W II (} 0 U {) 0 1 1 1 1 70-706 NATIONAL.FUCTRICAi.COLE 2008 Edition ANNEX C Annex C: Tables Table C.1 Continued FIXTURE WIRES Conductor Metric Designator(Trade Size) Size (ANVG/ 16 21 27 35 41 53 1�ype kemil) (1/2) (-1/4) (1) (11/a) (11/2) (2) FFH-2, RFH-2, 18 8 14 24 41 56 92 RFHH-3 16 7 12 20 34 47 78 SF-2,SFF-2 18 10 18 30 52 71 116 16 8 15 25 43 58 96 14 7 12 20 34 47 78 SF-1,SFF-1 18 18 33 53 92 125 206 RFH-1, R17I11-1-2, 18 14 24 39 68 92 152 TF,TFR XF, XFF RFHH-2,TR 16 11 19 31 55 74 123 TFF,XF,XFF XF,XFF 14 8 15 25 43 58 96 TFN,TFFN IS 22 38 63 108 148 244 16 17 29 48 83 113 186 PF,PFF, PGF, 18 21 36 59 103 140 231 PGFF,PAF, PTF, 16 16 28 46 79 108 179 PTFF,PAFF 14 12 21 34 60 81 134 ZF,ZFE ZHF, 18 27 47 77 133 181 298 HF, HFF 16 20 35 56 98 133 220 14 14 25 41 72 98 161 KF-2,KFF-2 18 39 69 111 193 262 433 16 27 48 78 136 185 305 14 19 33 54 93 127 209 12 13 23 37 64 87 144 l0 8 15 25 43 58 96 KF-1, KFF-1 18 46 82 133 230 313 516 16 33 57 93 161 220 362 14 22 38 63 108 148 244 12 14 25 41 72 98 161 10 9 16 27 47 64 105 XF,XFF 12 4 8 13 23 31 51 l0 3 6 10 18 24 40 Notes: I.This table is for concentric stranded conductors only. For compact stranded conductors,Table C.1(A) should be used. 2.Two-hour fire-rated RHH cable has ceramiliable insulation which has much larger diameters than other RHH wires. Consult manufacturer's conduit fill tables. *Types RHH, RHW, and RHW-2 without outer covering. 2008 Edition NATIONAL ELECTRICAL COIF 70-707 Annex C: Tables ANNEX C Table C.1(A) Maximum Number of Compact Conductors in Electrical Metallic Tubing (EMT) (Bused on Table 1, Chapter 9) COMPACT CONDUCTORS Conductor Metric Designator(Trade Size) Size (AWGI 16 2l 27 35 41 53 63 78 91 103 'v pe kcmil) (1/2) 0/4) (1) (11/4) (11/2) (2) (21.12) (3) (31/2) (4) THW, 8 2 4 6 11 16 26 46 69 90 115 THW-2, 6 1 3 5 9 12 20 35 53 70 89 THHW 4 1 2 4 6 9 15 26 40 52 67 2 1 1 3 5 7 11 19 29 38 49 1 1 1 1 3 4 8 13 21 27 34 110 1 1 l 3 4 7 l2 18 23 30 210 0 l 2 3 5 l0 15 20 25 310 1) 1 1 3 5 8 13 17 21 410 0 1 1 2 4 7 11 14 18 250 0 U 1 1 l 3 5 8 11 14 300 0 0 1 1 1 3 5 7 9 12 350 0 0 1 1 l 2 4 6 8 11 40(1 0 0 0 1 l 1 4 6 8 10 5(1(1 0 0 0 1 l 1 3 5 6 8 600 0 0 0 1 1 1 2 4 5 7 700 0 0 0 1 1 1 2 3 4 6 750 0 0 0 0 l 1 l 3 4 5 (0) 0 0 0 0 l 1 2 3 4 5 l(1(H) 0 U 0 0 1 1 l 2 3 4 THHN, 8 — — — — — — — — — — THWN, 6 2 4 7 13 18 29 52 78 102 130 THWN-2 4 1 3 4 8 11 18 32 48 63 81 2 l 1 3 6 8 13 23 34 45 58 1 1 1 2 4 6 10 17 26 34 43 II0 l l 1 3 5 8 14 22 29 37 210 l 1 1 3 4 7 12 18 24 30 310 U l 1 2 3 6 10 15 20 25 410 0 1 1 1 3 5 9 12 16 21 250 0 1 1 1 1 4 6 10 13 16 300 0 0 1 1 1 3 5 8 11 14 350 0 0 1 1 1 3 5 7 10 12 4(x1 0 0 1 1 1 2 4 6 9 11 500 0 U 0 l 1 l 4 5 7 9 600 0 U 0 1 1 l 3 4 6 7 700 0 U 0 l 1 l 2 4 5 7 750 0 0 0 l 1 1 2 4 5 6 9W 0 0 U 0 1 l 2 3 4 5 1(NH) 0 0 0 0 1 1 1 3 3 4 XHHW, 8 3 5 8 15 20 34 59 90 117 149 XHHW-2 6 l 4 6 11 15 25 44 66 87 Ill 4 l 3 4 8 11 18 32 48 63 81 2 l 1 3 6 8 13 23 34 45 58 1 l 1 2 4 6 10 17 26 34 43 1/0 l 1 1 3 5 8 14 22 29 37 210 l l 1 3 4 7 12 18 24 31 3I0 0 1 1 2 3 6 10 15 20 25 40 1 0 1 1 1 3 5 8 13 17 21 250 0 1 1 1 2 4 7 10 13 17 300 0 0 l 1 l 3 6 9 II 14 350 0 0 l 1 l 3 5 8 10 13 400 0 0 l 1 l 2 4 7 9 11 500 U 0 U 1 1 1 4 6 7 9 600 0 0 0 1 1 1 3 4 6 8 700 0 0 0 1 1 1 2 4 5 7 750 0 0 0 1 1 1 2 3 5 6 900 0 0 0 0 1 1 2 3 4 5 1000 U 0 0 U 1 1 1 3 4 5 Definition: Compact stranding is the result of a manufacturing process where the standard conductor is compressed to the extent that the interstices(voids between strand wires) are virtually eliminated. 70-708 NATIONAL ELECTRICAL CODE 2008 Edition ANNEX C Annex C: Tables Table C.2 Maximum Number of Conductors or Fixture Wires in Electrical Nonmetallic Tubing (ENT) (Based on Table 1, Chapter 9) CONDUCTORS Conductor Metric Designator(Trade Size) Size (AWG/ 16 21 27 35 41 53 Type kcmil) (1/2) (314) (1) (t'/4) (11/2) (2) RHH, RHW, 14 3 6 10 19 26 43 RHW-2 12 2 5 9 16 22 36 10 l 4 7 13 17 29 8 l 3 6 9 15 6 1 3 5 7 12 4 l 1 2 4 6 9 3 l 1 3 5 8 2 0 1 3 4 7 1 0 1 1 3 5 110 0 0 1 1 2 4 210 0 0 1 1 l 3 310 0 0 1 1 l 3 410 0 0 1 1 1 2 250 0 0 0 1 1 1 300 0 0 0 1 1 l 350 0 0 0 1 1 1 400 0 0 0 1 1 1 500 0 0 0 0 1 1 600 0 0 0 0 1 1 700 0 0 0 0 0 1 750 0 0 0 0 0 l 800 0 0 0 0 0 1 900 0 0 0 0 0 1 1000 0 0 0 0 0 1 1250 0 0 0 0 0 0 1500 0 0 0 0 0 0 1750 0 0 0 0 0 0 2000 0 0 0 0 0 0 TW 14 7 13 22 40 55 92 12 5 l0 17 31 42 71 10 4 7 13 23 32 52 8 l 4 7 13 17 29 RHH*, 14 4 8 15 27 37 61 RHW*, RHW-2*, THHW, TH W TH W-2 RHH*, 12 3 7 12 21 29 49 RHW*, RHW-2*, 10 3 5 9 17 23 38 THHW, TH W RHH*, 8 l 3 5 10 14 23 RHW*, RHW-2*, THHW, TH W, THW-2 (Continues) 2008 Edition NATIONAL ELECTRICAL CODE 70-7()9 Annex C: Tables ANNEX C Table C.2 Continued CONDUCTORS Conductor Metric Designator(Trade Size) Size (AWG/ 16 21 27 35 41 53 Type kcmil) (1/2) f'j) (1) (1'/a) (1'12) (2) RHH*, 6 1 2 4 7 10 17 RHW', 4 1 l 3 5 8 13 RHW-2•, 3 1 l 2 5 7 II TW.TH W. 2 1 1 2 4 6 9 THHW, 1 0 l 1 3 4 6 THW-2 110 0 l 1 2 3 5 210 U 1 1 1 3 5 310 0 0 1 1 2 4 410 (1 0 1 1 1 3 250 0 0 1 1 1 2 Six) 0 fl 0 1 1 2 350 0 0 0 1 1 1 40O 0 0 f} 1 1 1 5W 0 0 0 1 1 1 60() 0 0 o 0 1 1 7(H) 0 0 0 0 1 1 750 0 (1 0 0 1 l 8(H) 0 0 0 0 1 l 900 0 0 0 0 0 l 1000 0 0 n 0 0 1 1250 0 0 0 0 O 1 1500 0 0 0 0 p (} 1750 (1 0 0 O 0 0 2000 a 1) 0 0 0 0 THHN, 14 Ill 18 32 .5 M 80 132 THWN, 12 7 13 23 42 58 96 THWN-2 l0 4 8 15 26 36 60 8 2 5 8 15 21 35 6 3 6 11 15 25 4 1 4 7 9 15 3 1 3 5 8 13 2 1 2 5 6 11 1 1 1 3 5 8 1/0 0 1 l 3 4 7 210 0 1 l 2 3 5 310 0 1 l 1 3 4 410 (I 0 1 1 2 4 250 0 0 1 1 3 3(X) 0 0 1 P 1 2 350 0 f1 O P 1 2 400 0) 0 o n 1 1 500 0 0 0 1 1 1 6(H) 0 0 U 1 1 l 7(x1 0 0 0 0 1 l 750 (1 0 0 (1 1 l 800 0 0 0 0 1 1 (x)(} 0 0 0 0 1 1 IWO 0 0 0 (1 0 1 FEP, FEPB, 14 10 18 31 56 77 128 PFA,PFAH, 12 7 i3 23 41 56 93 TFF- 11) 5 9 16 29 40 67 8 3 5 9 17 23 38 6 1 4 6 12 16 27 4 1 2 4 8 11 19 3 1 1 4 7 9 16 2 1 1 3 5 8 13 70-710 NATIONAL ELECTRICAL CODE 2008 Edition ANNEX C Annex C: Tables Table C.2 Continued CONDUCTORS Conductor Metric Designator(Trade Size) Size (AWG/ 16 21 27 35 41 53 Type kcmil) (1h) ('14) (1) (11/s) (11/2) (2) PFA, PFAH, 1 I l l 4 5 9 TFE PFA, PFAH, 110 0 1 l 3 4 7 TFE,Z 210 0 1 l 2 4 6 3/0 0 1 l l 3 5 410 {) 1 1 1 2 4 Z 14 12 22 38 68 93 154 12 8 15 27 48 66 109 10 5 9 16 29 40 67 8 3 6 10 18 25 42 6 1 4 7 13 18 30 4 1 3 5 9 11 20 3 1 1 3 6 9 15 2 1 1 3 5 7 12 1 1 1 2 4 6 10 XHH, 14 7 13 22 40 55 92 XHHW, 12 5 l0 17 31 42 71 XHHW-2, M 4 7 13 23 32 52 Zw 8 1 4 7 13 17 29 6 1 3 5 9 13 21 4 1 4 7 9 15 3 1 3 6 8 13 2 1 2 5 6 11 XHH, 1 I 1 1 3 5 8 XHHW, 1/0 0 1 1 3 4 7 XHHW-2 210 0 1 1 2 3 6 310 0 1 1 1 3 5 410 0 0 l 2 4 250 0 0 l 1 1 3 3W 0 0 l 1 3 350 (1 0 l 1 1 2 400 0 0 0 1 1 1 500 0 0 0 l 1 1 600 0 0 0 l 1 1 700 0 0 0 0 1 1 750 0 0 0 0 1 1 800 0 0 0 0 1 1 900 0 {} 0 0 1 1 1000 0 0 0 0 0 l 1250 0 0 0 0 0 1 1500 0 0 0 0 0 1 1750 0 0 0 0 0 0 2000 0 0 0 0 0 0 2008 Edition NATIONAL ELECTRICAL CODE 70-711 Annex C: Tables ANNEX C Table C.2 Continued FIXTURE WIRES Conductor Metric Designator(Trade Size) Size (AWG/ 16 21 27 35 41 53 Type kcmil) (1/2) (-1/4) (1) (l'/4) (1'/2) (2) FFH-2, 18 6 12 21 39 53 88 RFH-2, 16 5 10 18 32 45 74 RFHH-3 18 8 15 27 49 67 111 SF-2,SFF-2 16 7 U 22 40 55 92 14 5 10 18 32 45 74 SF-1,SFF-1 18 15 28 -48 86 119 197 RFH-1, 18 11 20 35 64 88 145 RFHH-2,TF, TFF,XF, XFF RFHH-2,TR 16 9 I6 29 51 71 117 TI-F,XF, XFF XF,XFF 14 7 13 22 40 55 92 TFN.TFFN 18 l8 33 57 102 141 233 16 13 25 43 78 107 178 PK PFR 18 17 31 54 97 133 221 PGF, PGFF, 16 13 24 42 75 103 171 PAF, PTE, PTFK PAFF 14 l0 18 31 56 77 128 ZR ZFF, 18 22 40 70 125 172 285 IHF, HR 16 16 29 51 92 127 210 HFF 14 12 22 38 68 93 154 KF-2, KFF-2 18 31 58 101 182 210 413 16 22 41 71 128 176 291 14 15 28 49 88 121 200 12 l0 19 33 60 83 138 10 7 13 22 40 55 92 KF-1, KFF-I 18 38 69 121 217 298 493 16 26 49 85 152 209 346 14 18 33 57 102 141 233 12 12 22 38 68 93 154 1() 7 14 24 44 61 101 XF,XFF 12 3 7 12 21 29 49 10 3 5 9 17 23 38 Notes: 1. This table is for concentric stranded conductors only. For compact stranded conductors, Table C.2(A) should be used. 2.Two-hour fire-rated RHH cable has ceramifiabie insulation which has much larger diameters than other RHH wires. Consult manufacturer's conduit fill tables. *Types RHH, RHW, and RHW-2 without outer covering. 70-712 NATIONAL ELECTRICAL CODE 2008 Edition ANNEX C Annex C. Tables Table C.2(A) Maximum Number of Compact Conductors in Electrical Nonmetallic Tubing (ENT) (Based on Table 1, Chapter 9) COMPACT CONDUCTORS Conductor Metric Designator(Trade Size ) Size (AWGI 16 21 27 35 41 53 Type kcmil) (1/2) ('/4) (1) (1'/4) (11/x) (2) THW, 8 l 3 6 11 15 25 THW-2, 6 1 2 4 8 11 19 THHW 4 l 1 3 6 8 14 2 l 1 2 4 6 10 1 0 1 1 3 4 7 UO 0 1 1 3 4 6 210 0 l 1 2 3 5 310 0 1 1 1 3 4 410 1 0 0 1 1 2 4 250 0 0 1 1 1 300 0 0 1 1 1 2 350 0 0 0 1 1 2 400 0 0 0 1 1 1 500 0 0 0 1 1 1 600 0 0 0 1 1 1 7(x1 0 0 0 0 1 1 750 0 0 D 0 1 1 900 0 D 0 0 l 1 1000 0 0 0 0 0 1 THHN, 8 — — — — — THWN, 6 4 7 12 17 28 THWN-2 4 2 4 7 10 17 2 1 3 5 7 12 1 1 2 4 5 9 110 1 1 l 3 5 8 210 0 1 1 3 4 6 310 0 1 l 2 3 5 410 1 0 1 l 1 2 4 250 0 0 l 1 1 3 300 0 0 1 1 1 3 350 0 0 l 1 1 2 400 0 0 0 1 1 2 500 0 0 0 1 1 1 600 0 0 0 1 1 1 700 0 0 0 1 1 1 750 0 0 0 1 1 t 900 0 0 0 0 1 1 1000 0 0 0 0 1 1 XHHW, 8 2 4 8 14 19 32 XHHW-2 6 1 3 6 10 14 24 4 1 2 4 7 10 17 2 1 I 3 5 7 12 1 1 l 2 4 5 9 110 1 1 1 3 5 8 210 D 1 1 3 4 7 310 0 1 1 2 3 5 410 0 1 1 1 3 4 250 0 0 l 1 1 3 300 0 0 1 1 1 3 350 0 0 l 1 1 3 400 1 0 0 l 1 1 2 500 0 0 0 1 1 1 600 0 0 0 1 l 1 700 0 0 0 1 1 1 750 0 0 0 1 l 1 900 D 0 0 0 l ) 1000 0 0 0 0 1 I Definition: Compact stranding is the result of a manufacturing process where the standard conductor is compressed to the extent that the interstices(voids between strand wires) are virtually eliminated. 2008 Edition NATIONAL ELECTRICAL CODE 70-713 Annex C: Tables ANNEX C Table C.3 Maximum Number of Conductors or Fixture Wires in Flexible Metal Conduit (FMC) (Based on Table 1, Chapter 9) CONDUCTORS Conductor Metric Designator(Trade Size) Size (AWG/ 16 21 27 35 41 53 63 78 911 103 Type kcmil) ('/2) ('/A) (1) (11/4) (11/2) (2) (21/2) (3) (3 IA) (4) RHH, 14 4 7 11 17 25 44 67 96 131 171 RHW, 12 3 6 9 14 21 37 55 80 109 142 R11W-2 10 3 5 7 11 17 30 45 64 88 115 8 2 4 6 9 15 23 34 46 60 6 3 5 7 12 19 27 37 48 4 2 4 5 10 14 21 29 37 3 1 1 3 5 8 13 18 25 33 2 1 1 3 4 7 11 16 22 28 l 0 1 1 2 5 7 10 14 19 1/0 f) 1 1 2 4 6 9 12 16 210 0 1 1 1 l 3 5 8 11 14 310 () f) 1 1 l 3 5 7 9 12 410 0 [) 1 1 l 2 4 6 8 10 250 0 0 O 1 l 1 3 4 6 8 300 0 0 (} 1 l 1 2 4 5 7 350 (} 0 0 1 l 1 2 3 5 6 4(H) (} 0 0 {} l 1 1 3 4 6 500 0 [) 0 0 l 1 1 3 4 5 6(H) U 0 (} 0 l 1 1 2 3 4 700 U 0 0 0 0 1 1 l 3 3 750 U 0 0 0 0 1 1 l 2 3 SW 0 0 {} 0 0 1 1 l 2 3 9(H) 0 0 0 0 0 1 1 l 2 3 1 W 0 fl 0 0 0 I I I I 3 1250 0 (1 (} 0 0 O I l I l 1500 0 O 0 0 0 0 1 1 1 1 1750 0 (} 0 0 0 0 1 1 1 1 2{)pp 0 0 {} 0 0 0 0 1 1 l TW 14 9 15 23 36 53 94 141 203 277 361 12 7 II 13 28 41 72 108 156 212 277 10 5 8 13 21 30 54 81 116 158 207 8 3 5 11 17 30 45 64 88 115 RHH*, 14 6 10 15 24 35 62 94 135 184 240 RHW*, RHW-2*, THHW, TH W, TH W-2 RHH1, 12 5 8 12 19 28 50 75 108 148 193 RHW*, RHW-2* 10 4 6 10 15 22 39 59 85 115 151 THHW, TH W RHH*, 8 1 4 6 9 13 23 35 51 69 90 RHW'", RHW-21, THIf W. TH W, THW-2 70-714 NATIONAL RUCTRICAL CODE. 2008 Edition ANNEX C Annex C; Tables Table C.3 Continued CONDUCTORS Conductor Metric Designator(Trade Size) Size (AWGI 16 21 27 35 41 53 63 78 91 103 Type kcmil) ('h) (3/4) (1) (11/4) (11/2) (2) (21/2) (3) (31/2) (4) RHH*, 6 1 3 4 7 10 18 27 39 53 69 RHW*. 4 1 3 5 7 13 20 29 39 51 RHW-2*, 3 1 3 4 6 11 17 25 34 44 TW 2 1 2 4 5 10 14 21 29 37 Tom' I 1 1 2 4 7 10 15 20 26 THHW, THW-2 110 0 1 1 1 3 6 9 12 17 22 210 0 1 1 1 3 5 7 10 14 19 310 0 1 1 1 2 4 6 9 12 16 410 0 0 1 1 1 3 5 7 l0 13 250 0 0 1 1 1 3 4 6 8 11 300 0 0 1 1 1 2 3 5 7 9 350 0 0 0 l l 1 3 4 6 8 400 0 0 0 l l 1 3 4 6 7 500 0 0 0 l l 1 2 3 5 6 600 0 0 0 0 l 1 1 3 4 5 700 0 0 0 0 l 1 1 2 3 4 750 0 0 0 0 l 1 1 2 3 4 800 0 0 0 0 l 1 1 1 3 4 900 0 0 0 0 0 1 1 1 3 3 1000 0 0 0 0 0 l 1 1 2 3 1250 0 0 0 0 0 l 1 1 1 2 1500 0 0 0 0 0 0 1 1 1 1 1750 0 0 0 0 0 0 1 1 1 1 2000 0 0 0 0 0 0 1 1 1 1 THHN, 14 13 22 33 52 76 134 202 291 396 518 THWN, 12 9 16 24 38 56 98 147 212 289 378 THWN-2 10 6 10 15 24 35 62 93 134 182 238 8 3 6 9 14 20 35 53 77 105 137 6 2 4 6 10 14 25 38 55 76 99 4 1 2 4 6 9 16 24 34 46 61 3 1 1 3 5 7 13 20 29 39 51 2 1 1 3 4 6 11 17 24 33 43 l 1 1 1 3 4 8 12 18 24 32 110 1 l 1 2 4 7 10 15 20 27 210 0 1 1 1 3 6 9 12 17 22 310 0 1 1 1 2 5 7 10 14 Is 410 0 l 1 1 1 4 6 8 12 15 250 0 0 1 1 1 3 5 7 9 12 300 0 0 1 1 1 3 4 6 8 11 350 0 0 1 1 1 2 3 5 7 9 400 0 0 0 1 1 1 3 5 6 8 500 0 0 0 1 1 1 2 4 5 7 600 0 0 0 0 l l 1 3 4 5 700 0 0 0 0 l l 1 3 4 5 750 0 0 0 0 l l 1 2 3 4 800 0 0 0 0 l l 1 2 3 4 900 0 0 0 0 0 l 1 1 3 4 1000 0 0 0 0 0 l l l 3 3 FEP, 14 12 21 32 51 74 130 196 282 385 502 FBPB, 12 9 15 24 37 54 95 143 206 281 367 PFA, 10 6 11 17 26 39 68 103 148 201 263 PFAH, 8 4 6 10 15 22 39 59 85 115 151 TFE 6 2 4 7 11 16 28 42 60 82 107 4 3 5 7 11 19 29 42 57 75 3 2 4 6 9 16 24 35 48 62 2 1 3 5 7 13 20 29 39 51 (Continues) 2008 Edition NATIONAL ELECTRICAL CODE 70-715 Annex C: Tables ANNEX C Table C.3 Continued CONDUCTORS Conductor Metric Designator(Trade Sire) Size (AWG/ 16 21 27 35 41 53 63 78 91 103 Type kcmil) (t/2) ('/a) (t) (11 14) (11/2) (2) (21/2) (3) (3°/2) (4) PFA. I 1 1 2 3 5 9 14 20 27 36 PFAH, TFE PFA, 110 1 1 1 3 8 11 l7 23 30 PFAH, 210 1 1 l 2 3 6 9 14 19 24 TFE,Z 310 0 1 1 l 3 5 8 11 15 20 410 0 1 1 l 2 4 6 9 13 16 Z 14 15 25 39 61 89 157 236 340 463 605 12 11 IN 28 43 63 111 168 241 329 429 10 6 11 17 26 39 68 103 148 201 263 8 4 7 11 17 24 43 65 93 127 166 6 3 5 7 12 17 30 45 65 89 117 4 1 3 5 8 12 21 31 45 61 80 3 1 2 4 6 8 IS 23 33 45 58 2 1 1 3 5 7 12 19 27 37 49 1 1 1 2 4 6 M 15 22 30 39 XHH, l4 9 15 23 36 53 94 141 203 277 361 XHHW, 12 7 11 1N 28 41 72 108 156 212 277 XHHW-2, l0 8 13 21 30 54 81 116 158 207 1W 8 5 7 11 17 30 45 64 88 115 6 3 5 8 12 22 33 48 65 85 4 d 2 4 6 9 16 24 34 47 61 3 1 1 3 5 7 13 20 29 40 52 2 1 1 3 4 6 11 17 24 33 44 XHH, 1 1 1 3 5 K 13 18 25 32 XHHW, IM) 1 1 2 4 7 10 15 21 27 XHHW-2 210 0 l 1 2 3 6 9 13 17 23 310 0 l 1 l 3 5 7 10 14 19 4/0 0 1 1 l 2 4 6 9 12 15 250 U 0 1 1 1 3 5 7 10 13 300 0 0 1 1 1 3 4 6 8 11 350 0 0 1 l 1 2 4 5 7 9 400 0 0 0 1 1 l 3 5 6 8 50(1 0 0 0 1 1 1 3 4 5 7 600 0 0 U 0 1 1 1 3 4 5 700 () 0 U 0 1 1 1 3 4 5 750 O 0 (I 0 1 1 1 2 3 4 8W O 0 0 0 1 1 1 2 3 4 900 O f) f] 0 0 1 1 1 3 4 1000 O f) {} 0 f) 1 ] 1 3 3 1250 0 0 (} 0 O 1 1 1 1 3 1500 (1 f) 0 {) O 1 1 1 1 2 1750 0 O 0 0 (} 0 1 1 1 1 2000 0 0 0 {l 0 (} 1 1 1 1 70-716 NATIONAL ELECTRICAL CODE 2008 Edition ANNEX C Annex C: Tables Table C.3 Continued FIXTURE WIRES Conductor Metric Designator('Trade Size) Size (AWG/ 16 21 27 35 41 53 TWpe kemil) (Yz) (314) (1) (P/4) (1112) (2) FFH-2, 18 8 14 22 35 51 90 RFH-2, 16 7 12 19 29 43 76 RFHH-3 SF-2,SFF-2 l8 11 18 28 44 64 113 16 9 15 23 36 53 94 14 7 12 19 29 43 76 SF-1,SFF-1 16 19 32 50 78 114 201 RF11-1, 18 14 24 37 58 84 148 RFHH-2,TF, TFF,XF, XFF RFHH-2,TF, 16 11 19 30 47 68 120 TFF,XF, XFF XF,XFF 14 9 15 23 36 53 94 TFN,TFFN 18 23 38 59 93 135 237 16 [7 29 45 71 103 181 PF, PFF, 18 22 36 56 88 128 225 PGF, PGFF. 16 17 28 43 68 99 174 PAF, PT F, PTFF,PAFF 14 12 21 32 51 74 130 ZF,ZFF, 18 28 47 72 113 165 290 ZHF,HF, 16 20 35 53 83 121 214 HFF 14 15 25 39 61 89 157 KF-2. KFF-2 18 41 68 105 164 239 421 16 28 48 74 116 168 297 14 19 33 51 80 116 204 12 13 23 35 55 80 140 10 9 15 23 36 53 94 KF-1, KFF-1 18 48 82 125 196 285 503 16 34 57 88 138 200 353 14 23 38 59 93 135 237 12 15 25 39 61 89 157 10 10 16 25 40 58 103 XF,XFF 12 5 8 12 19 28 50 10 4 6 10 15 22 39 Notes: L This table is for concentric stranded conductors only. For compact stranded conductors,Table C.3(A) should be used. 2. Two-hour fire-rated RHH cable has ceramifiable insulation which has much larger diameters than other RHH wires. Consult manufacturer's conduit till tables. Types RHH, RHW, and RHW-2 without outer covering. 2008 Edition NATIONAL ELECTRICAL CODE 70--717 Annex C: Tables ANNEX C Table C.3(A) Maximum Number of Compact Conductors in Flexible Metal Conduit (FMC) (Buser!on Table 1, Chapter 9) COMPACT CONDUCTORS Conductor Metric Designator(Trade Size) Size (AWGI 16 21 27 35 41 53 63 78 91 103 1', a kcmil) ('/2) {'/r) (1) (P/a) (11/2) (2) (21/2) (3) (31/2.) (4) THW. 8 2 4 6 10 14 25 38 55 75 98 THHW. 5 1 3 5 7 11 20 29 43 58 76 THW-2 4 1 2 3 5 8 15 22 32 43 57 2 1 1 2 4 6 11 16 23 32 42 l 1 1 1 3 4 7 11 16 22 29 110 1 1 1 2 3 6 10 14 19 25 210 0 1 1 1 3 5 8 12 16 21 310 1) 1 1 1 2 4 7 10 14 18 410 1 0 1 1 1 1 4 6 8 11 15 250 0 0 1 1 1 3 4 7 9 12 300 0 0 1 1 1 2 4 6 8 10 350 0 0 1 1 1 2 3 5 7 9 400 0 0 0 1 1 1 3 5 6 8 5(x) 0 0 0 1 1 1 3 4 5 7 6M 0 U 0 0 1 1 1 3 4 6 700 0 0 0 0 1 1 1 3 4 5 750 0 0 0 0 1 1 1 2 3 5 900 () 0 0 0 1 1 1 2 3 4 1000 0 (Y 0 0 0 1 l 1 3 4 THHN, 8 — — — — — — — — THWN, 6 3 4 7 II 16 29 43 62 85 111 THWN-2 4 l 3 4 7 10 18 27 38 52 69 2 l 1 3 5 7 13 19 28 38 49 1 1 2 3 5 9 14 21 28 37 1/0 l 1 1 3 4 8 12 17 24 31 210 1 1 1 2 4 6 10 14 20 26 310 0 1 1 1 3 5 8 12 17 22 4/0 ❑ 1 1 1 2 4 7 10 14 18 250 0 1 1 1 1 3 5 8 11 14 300 0 0 1 1 1 3 5 7 9 12 350 0 0 1 1 1 3 4 6 8 10 400 0 0 1 1 1 2 3 5 7 9 501) 0 0 0 1 1 1 3 4 6 8 601) 0 U 0 1 1 1 2 3 5 6 7(10 0 U 0 0 1 1 1 3 4 6 750 U 0 0 0 1 1 l 3 4 5 9W U 0 0 0 1 1 1 2 3 4 1000 U 0 U 0 0 1 l 1 3 4 XHHW. 8 3 5 8 I3 19 33 50 71 97 127 XHHW-2 6 2 4 6 9 14 24 37 53 72 95 4 1 3 4 7 10 18 27 38 52 69 2 1 1 3 5 7 13 19 28 38 49 1 1 1 2 3 5 9 14 21 28 37 110 1 1 1 3 4 8 12 17 24 31 210 1 l 1 2 4 7 10 15 20 26 310 0 l 1 1 3 5 8 12 17 22 4/0 0 1 1 1 2 4 7 10 14 18 250 0 l 1 1 1 4 5 8 11 14 300 0 0 1 1 1 3 5 7 9 12 350 0 0 1 1 1 3 4 6 8 11 400 0 0 1 1 1 2 4 5 7 10 500 0 0 0 l 1 l 3 4 6 8 600 0 0 0 1 1 l 2 3 5 6 700 0 0 0 0 1 1 1 3 4 6 750 U 0 0 0 1 l 1 3 4 5 900 0 0 0 0 1 l 2 2 3 4 1000 0 0 0 0 1 1 1 2 3 4 Definition: Compact stranding is the result of a manufacturing process where the standard conductor is compressed to the extent that the interstices(voids between strand wires) are virtually eliminated. 70-718 NATIONAL ELt3CrRICAL CODE 2008 Edition ANNEX C Annex C: Tables Table CA Maximum Number of Conductors or Fixture Wires in Intermediate Metal Conduit(IMC) (Based on Table 1, Chapter 9) CONDUCTORS Conductor Metric Designator(Trade Size) Size (AWG/ 16 21 27 35 41 53 63 78 91 103 Type kemil) ('/z) (3/4) (1) (11/4) (I1/2) (2) (2'/2) (3) (31/2) (4) RHH, 14 4 8 13 22 30 49 70 108 144 186 RHW, 12 4 6 11 18 25 41 58 89 120 154 RHW-2 RHH, 10 3 5 8 15 20 33 47 72 97 124 RHW, 8 1 3 4 8 l0 17 24 38 50 65 RHW-2 6 1 1 3 6 8 14 19 30 40 52 4 1 1 3 5 6 11 15 23 31 41 3 1 1 2 4 6 9 13 21 28 36 2 1 1 l 3 5 8 11 18 24 31 1 0 1 1 2 3 5 7 12 16 20 110 0 1 1 1 3 4 6 10 14 Is 210 0 1 1 1 2 4 6 9 12 15 310 0 0 1 1 1 3 5 7 10 13 410 0 0 1 1 1 3 4 6 9 11 250 0 0 1 1 1 1 3 5 6 8 300 0 0 0 1 l 1 3 4 6 7 350 0 0 0 1 l 1 2 4 5 7 400 0 0 0 1 l 1 2 3 5 6 500 0 0 0 1 l 1 1 3 4 5 600 0 0 0 0 l 1 l 2 3 4 700 0 0 0 0 l 1 1 2 3 4 750 0 0 0 0 I 1 1 1 3 4 800 0 0 0 0 0 l 1 1 3 3 900 0 0 0 0 0 l 1 1 2 3 1000 0 0 0 0 0 l 1 l 2 3 1250 0 0 0 0 0 1 1 1 l 2 1500 0 0 0 0 0 0 1 l l l 1750 0 0 0 0 0 0 1 l l l 2000 0 0 0 0 0 0 1 l 6 1 l TW 14 l0 17 27 47 64 104 147 228 %r 392, 12 7 13 21 36 49 80 113 175 234 301 10 5 9 15 27 36 59 84 130 174 224 8 3 5 8 15 20 33 47 72 97 124 RHH*, 14 6 11 18 31 42 69 98 151 202 261 RHW*, RHW-2*, THHW, THW, THW-2 RHH*, 12 5 9 14 25 34 56 79 122 163 209 RHW*, TH 10 4 7 11 19 26 43 61 95 127 163 THHWHW. THW RHH*, 8 2 4 7 12 16 26 37 57 76 98 RHW*, RHW-2*, THHW, THW, THW-2 RHH*, 6 1 RHW*, RHW-2*, Tw 4 1 2 4 6 9 15 21 32 43 56 THHW, THW, THW-2 (Confinues) 2008 Edition NATIONAL ELECTRICAL CODE 70-719 Annex C: Tables ANNEX C Table CA Continued CONDUCTORS Conductor Metric Designator(Trade Size) Size (AWG/ 16 21 27 35 41 53 63 78 91 103 Type kcmil) I1/2) (1/4) (l) (11/4) (11/2) (2) (21/2) (3) (31/2) (4) RHH*, 3 l l 3 6 8 13 l8 28 37 48 RHW¢, 2 l l 3 5 6 11 15 23 31 41 RHW_2*, I l 1 1 3 4 7 11 16 22 28 TW i/0 1 1 1 3 4 6 9 14 19 24 THW. 210 0 1 1 2 3 5 8 12 16 20 THHW 310 U l 1 1 3 4 6 10 13 17 THW-2 410 0 l 1 I 2 4 5 8 11 14 250 0 0 l 1 1 3 4 7 9 12 3(x) 0 () l 1 1 2 4 6 8 10 350 0 0 l l 1 2 3 5 7 9 400 0 0 0 I 1 1 3 4 6 8 500 0 0 0 I 1 1 2 4 5 7 6(x) 0 U 0 I I 1 1 3 4 5 7(x) 0 U 0 0 1 1 1 3 4 5 750 0 0 0 0 1 1 1 2 3 4 800 0 0 0 0 1 1 1 2 3 4 901) 1) U 0 0 1 1 1 2 3 4 1001 0 U 0 (] 0 1 1 1 3 3 1250 0 0 0 0 {) 1 1 1 1 3 15(x) O 0 0 0 {) 1 1 1 1 2 1750 0 0 0 0 0 0 1 1 1 1 2000 0 0 0 0 0 0 1 1 1 1 THHN. 14 14 24 39 68 91 149 211 326 436 562 THWN, 12 10 17 29 49 67 109 154 238 318 410 THWN-2 10 6 1` 18 31 42 68 97 150 200 258 8 3 6 10 18 24 39 56 86 115 149 6 2 4 7 13 17 28 40 62 83 107 4 1 3 4 8 10 17 25 38 51 66 3 1 2 4 6 9 15 21 32 43 56 2 1 1 3 5 7 12 17 27 36 47 1 1 1 2 4 5 9 13 20 27 35 110 I 1 l 3 4 8 11 17 23 29 210 I 1 3 4 6 9 14 19 24 3/() 0 l 2 3 5 7 12 16 20 410 0 1 l 1 2 4 6 9 13 17 250 0 0 l l 1 3 5 8 ]0 13 3W 0 0 l I 1 3 4 7 9 12 350 0 0 l I 1 2 4 6 8 10 400 0 0 l I 1 2 3 5 7 9 5{x) U 0 0 1 1 1 3 4 6 7 600 0 0 0 1 1 1 2 3 5 6 700 0 0 0 l 1 1 l 3 4 5 750 U 0 0 ( 1 1 l 3 4 5 800 U 0 0 0 1 1 1 3 4 5 900 0 0 0 0 1 1 l 2 3 4 IWO 0 0 0 0 1 1 l 2 3 4 FER 14 13 23 38 66 89 145 205 317 423 545 FEPB, 12 10 17 28 48 65 106 150 231 309 398 PFA, 10 7 12 20 34 46 76 107 166 221 285 PFAH, 8 4 7 11 19 26 43 61 95 127 163 TFE 6 3 5 8 14 19 31 44 67 90 116 4 1 3 5 10 13 21 30 47 63 81 3 1 3 4 8 11 18 25 39 52 68 2 1 2 4 6 9 15 21 32 43 56 70-720 NATIONAL ELFUTRICAL CODE 2008 Edition ANNEX C Annex C: Tables Table CA Continued CONDUCTORS Conductor Metric Designator(Trade Size) Size (AWG/ 16 21 27 35 41 53 63 78 91 103 Type kcmil) (1/2) 0/4) (1) (1114) (11/2) (2) (21/1) (3) (311:0 (4) PFA. I 1 1 2 4 6 10 14 22 30 39 PFA H, TFE PFA, 1/0 l 1 1 4 5 8 12 19 25 32 PFAH, 2/0 l 1 1 3 4 7 10 15 21 27 TFE,Z 310 0 1 1 2 3 6 8 13 17 22 410 0 1 1 1 3 5 7 10 14 18 Z 14 16 28 46 79 107 175 247 381 510 657 12 Il 20 32 56 76 124 175 271 362 466 10 7 12 20 34 46 76 107 166 221 285 8 4 7 12 21 29 48 68 105 140 180 6 3 5 9 15 20 33 47 73 98 127 4 l 3 6 10 14 23 33 50 67 87 3 1 2 4 7 10 17 24 37 49 63 2 1 1 3 6 8 14 20 30 41 53 1 1 1 3 5 7 11 16 25 33 43 X H H, 14 10 17 27 47 64 104 147 228 304 392 XHHW, 12 7 13 21 36 49 80 Ili 175 234 301 XHHW-2, 10 5 9 15 27 36 59 84 130 174 224 ZW 8 3 5 8 15 20 33 47 72 97 124 6 1 4 G 11 15 24 35 53 71 92 4 1 3 4 8 11 18 25 39 52 67 3 1 2 4 7 9 15 21 33 44 56 2 1 1 3 5 7 12 18 27 37 47 XHH, I 1 1 2 4 5 9 13 20 27 35 XHHW, IA) I 1 1 3 5 8 11 17 23 30 XHHW-2 2/U 1 1 1 3 4 6 9 14 19 25 310 0 1 1 2 3 5 7 12 16 20 410 0 1 1 1 2 4 6 10 13 17 250 0 (I 1 1 1 3 8 11 14 300 t (I 1 1 1 3 4 7 9 12 350 {) (1 1 1 1 3 4 6 8 10 4W 0 0 I 1 1 2 3 5 7 9 500 0 0 0 1 l 1 3 4 6 8 600 0 0 0 1 1 1 2 3 5 6 700 0 0 0 l 1 1 1 3 4 5 750 0 0 0 l 1 1 1 3 4 5 8(K) (I 0 0 0 l 1 1 3 4 5 900 0 1 0 0 1 1 l 2 3 4 1((x) 0 0 0 U l 1 1 2 3 4 1250 0 0 0 0 0 1 1 1 2 3 1500 0 0 0 0 0 1 l 1 l 2 1750 0 0 0 0 0 1 l 1 1 2 2000 0 0 0 0 0 0 1 1 1 l (Continues) 2008 Edition NATIONAL ELECTRICAL CODE 70-721 Annex C: Tables ANNEX C Table CA Continued FIXTURE WIRES Conductor Metric Designator(Trade Size) Size (AWGI 16 21 27 35 41 53 Type kemil) (1/2) ON (1) (11/4) (11/2) (2) FHH-2, 18 9 16 26 45 61 100 RFH-2, 16 8 13 22 38 51 84 RFHH-3 SF-2,SFF-2 18 12 20 33 57 77 126 16 10 17 27 47 64 104 14 8 13 22 38 51 84 SF-1,SFF-1 18 21 36 59 101 137 223 RFH-1. 18 15 26 43 75 l01 165 RFHH-2,TR TFF. XF. XFF RF11-2,TF, 16 12 21 35 60 81 133 TFF,XF, XFF XF, XFF 14 10 17 27 47 64 104 TFN,'ITFN l8 25 42 69 119 161 264 16 19 32 53 91 123 201 PF,PFF, 18 23 40 66 113 153 250 PGF.PGFF, 16 18 31 51 87 118 193 PAR PTF, PTFF.PAFF 14 13 23 38 66 89 145 ZF,ZFF, 18 30 52 85 146 197 322 ZHF, HF, 16 22 38 63 108 145 238 HFF 14 16 28 46 79 107 175 KF-2, KFF-2 18 44 75 123 212 287 468 16 31 53 87 149 202 330 14 21 36 60 103 139 227 12 14 25 41 70 95 156 10 10 17 27 47 64 104 KF-1, KFF-l l8 52 90 147 253 342 558 16 37 63 103 178 240 392 14 25 42 69 119 161 264 12 16 28 46 79 107 175 10 10 18 30 52 70 114 XF.XFF 12 5 9 14 25 34 56 10 4 7 11 19 26 43 Notes: 1.This table is for concentric stranded conductors only. For compact stranded conductors,Table CA(A) should be used. 2.Two-hour fire-rated RHH cable has ceramifiable insulation which has much larger diameters than other RHH wires. Consult manufacturer's conduit fill tables. 'Types RHH, RHW, and RHW-2 without outer covering. 70-722 NATIONAL ELECTRICAL CODE 2008 Edition ANNEX C Annex C: Tables Table CA(A) Maximum Number of Compact Conductors in Intermediate Metal Conduit (1MC) (Bused on Table 1, Chapter 9) COMPACT CONDUCTORS Conductor Metric Designator(Trade Size) Size (AWG/ 16 21 27 35 41 53 63 78 91 103 Tr kcmil) (1/2) (1/4) (1) (1i'/4) (lc/2) (2) (2'/x) (3) (3 IA) (4) THW, 8 2 4 7 13 17 28 40 62 83 107 THW-2, 6 1 3 6 10 13 22 31 48 64 82 THHW 4 1 2 4 7 W 16 23 36 48 62 2 1 1 3 5 7 12 17 26 35 45 1 1 1 l 4 5 8 42 18 25 32 110 1 1 l 3 -1 7 10 16 21 27 210 0 1 l 3 4 6 9 13 18 23 310 0 1 l 2 3 5 7 11 15 20 410 1 0 1 l 1 2 4 6 9 13 16 250 O 17 l 1 l 3 5 7 10 13 300 0 0 l 1 1 3 4 6 9 11 350 0 l) l 1 l 2 4 6 8 10 400 0 0 l 1 1 2 3 5 7 9 500 0 0 0 1 l 1 3 4 6 8 600 0 0 U 1 1 l 2 3 5 6 700 0 0 0 1 l 1 1 3 4 5 750 0 0 U 1 l l l 3 4 5 900 0 0 0 0 l 1 1 2 3 4 1000 U 0 0 U l l l 2 3 4 THHN, 8 — — — — — — — — — — THWN, 6 3 5 8 14 19 32 45 70 93 120 THWN-2 4 1 3 5 9 12 20 28 43 58 74 2 1 1 3 6 8 14 20 31 41 53 1 1 1 3 5 6 10 15 23 31 40 110 l 1 2 4 5 9 13 20 26 34 2/0 l 1 l 3 4 7 10 16 22 28 310 0 1 l 3 4 6 9 14 18 24 410 1 0 1 l 2 3 5 7 11 15 19 250 0 1 1 1 2 4 6 9 12 15 300 0 0 l 1 l 3 5 7 10 13 350 0 0 l 1 l 3 4 7 9 11 400 0 0 l 1 l 2 4 6 8 10 5W 0 0 l 1 l 2 3 5 7 9 6(H) U 0 0 1 1 1 2 4 5 7 700 0 0 0 1 l 1 2 3 5 6 750 U U 0 1 l 1 1 3 4 6 900 0 0 0 U l 1 2 3 3 5 1000 U 0 0 0 l 1 1 2 3 4 XHHW, 8 3 6 9 16 22 37 52 80 107 138 XHHW-2 6 2 4 7 12 16 27 38 59 80 103 4 3 5 9 12 20 28 43 58 74 2 1 1 3 6 8 14 20 31 41 53 l 1 1 3 5 6 10 15 23 31 40 110 1 1 2 4 5 9 13 20 26 34 210 1 1 l 3 4 7 11 17 22 29 310 0 1 l 3 4 6 9 14 18 24 410 1 0 1 l 2 3 5 7 11 15 20 250 0 1 l l 2 4 6 9 12 16 300 0 U l l 1 3 5 8 10 13 350 0 0 l l 1 3 4 7 9 12 400 0 0 l l 1 3 4 6 8 11 500 0 0 l l 1 2 3 5 7 9 600 0 0 0 l 1 1 2 4 5 7 700 0 0 0 l 1 1 2 3 5 6 750 0 0 0 l 1 1 1 3 4 6 900 0 0 0 0 1 1 I 3 4 5 1000 1 0 0 0 0 1 1 1 2 3 4 Definition: Compact stranding is the result of a manufacturing process where the standard conductor is compressed to the extent that interstices (voids between strand wires) are virtually eliminated. 2008 Edition NATIONAL ELECTRICAL CODE 70--723 Annex C: Tables ANNEX C Table C.5 Maximum Number of Conductors or Fixture Wires in Liquidtight Flexible Nonmetallic Conduit(Type LFNC-B*) (Based on Table 1, Chapter 9) CONDUCTORS Conductor Metric Designator('Dade Size) Size (AWG/ 12 16 21 27 35 41 53 T ve kemil) ('/e) ('1:) (314) I1) (1114) (11/2) (2) RHH, 14 2 4 7 12 21 27 44 RHW, 12 l 3 6 10 17 22 36 RHW-2 10 l 3 5 8 14 18 29 8 l 1 2 4 7 9 15 6 l 1 1 3 6 7 12 4 0 1 1 2 4 6 9 3 0 1 1 1 4 5 8 2 0 1 1 1 3 4 7 1 0 0 1 1 1 3 5 Ito 0 0 1 1 1 2 4 210 0 0 1 1 1 1 3 310 0 0 0 1 1 1 3 410 0 0 0 1 1 1 2 250 0 0 0 0 1 1 1 300 0 0 0 0 1 1 1 350 0 0 0 0 1 1 1 400 0 0 0 0 l 1 1 500 0 0 0 0 l 1 1 600 0 0 0 0 0 1 1 700 0 0 0 0 0 0 1 750 0 0 0 0 0 0 1 800 0 0 0 0 0 0 1 900 o 0 0 0 0 0 1 1000 0 0 0 0 0 0 1 1250 0 0 0 0 0 0 0 1500 0 0 0 0 0 0 0 1750 0 0 0 0 0 0 0 2000 0 U 0 0 0 0 0 TW 14 5 9 15 25 44 57 93 12 4 7 12 19 33 43 71 10 3 5 9 14 25 32 53 8 1 3 5 8 14 18 29 RHH', 14 3 6 10 16 29 38 62 RHW ,, RHW-2 . THHW, THW, THW-2 RHH' , 12 3 5 8 13 23 30 50 RHW . RHW-2 . 10 1 3 6 10 18 23 39 THHW, THW RHH', 8 1 1 4 6 11 14 23 RHW RHW-2 , THHW, THW, THW-2 RHH , 6 1 1 3 5 8 11 18 RHW`, RHW-2', 4 1 1 l 3 6 8 13 TW,THW, THHW, 3 1 1 l 3 5 7 11 THW-2 70-724 NATIONAL ELECTRICAL CODE 2008 Edition ANNEX C Annex C: Tables Table C.5 Continued CONDUCTORS Conductor Metric Designator(Trade Size) Size (AWG/ 12 16 21 27 35 41 53 Type kcmil) (3/21 (1/2) (3t4} (1) (1Y+) (1L/2) (2) RHH', 2 U 1 1 2 4 6 9 RHW , 1 U 1 1 l 3 4 7 RHW-2 , 110 0 0 1 l 2 3 6 TW,THW, 410 0 0 1 l 2 3 5 THHW, 310 0 0 1 l l 2 4 THW-2 4/0 0 0 0 l 1 l 3 250 0 0 0 l 1 l 3 300 0 0 0 l 1 l 2 350 0 0 0 U 1 l 1 400 0 0 (1 0 1 l 1 500 0 0 0 0 l l 1 600 0 (1 U 0 1 l 1 700 0 0 0 0 0 1 1 750 U 0 0 0 0 1 1 800 0 0 0 0 0 1 1 900 0 0 O 0 U 0 1 1000 0 U O 0 0 0 1 1250 0 U 0 0 0 0 1 1500 U (1 0 0 0 0 0 1750 U 0 0 0 0 0 0 21)00 U 0 0 U 0 0 0 THHN, 14 8 13 22 36 63 81 133 THWN, 12 5 9 16 26 46 59 97 THWN-2 10 3 6 10 16 29 37 61 8 l 3 6 9 16 21 35 6 l 2 4 7 12 15 25 4 l l 2 4 7 9 15 3 l l 1 3 6 8 13 2 1 l 1 3 5 7 11 1 U l 1 1 4 5 S 1/0 0 l 1 1 3 4 7 2/0 0 0 1 1 2 3 6 3/0 0 0 1 1 1 3 5 4/0 0 0 1 4 1 2 4 250 0 0 0 6 1 1 3 300 U 0 0 1 1 1 3 350 0 0 0 i 1 1 2 400 0 0 0 0 1 I 1 500 0 0 0 0 ! 1 1 600 I1 0 O 0 1 1 1 700 0 0 0 0 1 1 1 750 0 0 0 0 0 1 1 SW 0 0 0 0 0 1 1 900 0 0 0 0 0 1 1 1 O 0 0 0 0 0 0 1 FEP. 14 7 12 21 35 61 79 129 FEPB, 12 5 9 15 25 44 57 94 PFA, 10 4 6 11 18 32 41 68 PFAH, 8 1 3 6 10 18 23 39 TFE 6 1 2 4 7 13 17 27 4 1 l 3 5 9 12 19 3 1 l 2 4 7 10 16 2 1 l l 3 6 8 13 PFA, 1 0 l 1 2 4 5 9 PFAH, TFE PFA, 1/0 0 l l 1 3 4 7 PFAH (Continues) 2008 Edition NATIONAL ELECTRICAL CODE 70-725 Annex C: Tables ANNEX C Table C.5 Continued CONDUCTORS Conductor Metric Designator(Trade Size) Size (AWGI 12 16 21 27 35 41 53 Type kcmil) 0/8) (yz) (-'ia) (1) (1'/a) (1L/2) (2) TFE,Z 210 0 1 1 1 3 4 fi 310 0 0 1 1 2 3 5 410 0 0 1 1 1 2 4 Z 14 9 15 26 42 73 95 156 12 6 10 18 30 52 67 111 10 4 6 11 18 32 41 68 8 2 4 7 11 20 26 43 6 1 3 5 8 14 18 30 4 1 l 3 5 9 12 20 3 1 l 2 4 7 9 15 2 (l l l 3 6 7 12 1 0 1 1 2 5 6 10 XHH, 14 5 9 15 25 44 57 93 XHHW, 12 4 7 12 19 33 43 71 XHHW-2, 10 3 5 9 14 25 32 53 ZW 8 1 3 5 8 14 is 29 6 1 1 3 6 10 13 22 4 1 1 2 4 7 9 16 3 1 1 1 3 6 8 13 2 1 1 1 3 5 7 lI XHH, 1 U 1 1 1 4 5 8 XHHW, IA) U 1 1 1 3 4 7 XHHW-2 210 U 0 1 1 2 3 6 310 0 0 1 1 1 3 5 410 0 0 1 1 1 2 4 250 0 0 0 1 1 1 3 300 0 0 0 1 1 1 3 350 0 0 0 l 1 1 2 400 0 0 U 0 1 1 1 500 0 U 0 U 1 1 1 600 U 1 1 700 0 0 0 U 1 1 1 750 0 0 0 0 U 1 1 800 0 0 0 0 0 1 1 900 0 0 0 0 0 1 1 1000 0 U 0 0 0 U 1 1250 0 U 0 0 U U 1 1500 U U U 0 0 0 1 1750 0 U 0 0 0 0 0 2000 0 0 0 0 0 0 0 FIXTURE WIRES FFH-1 18 5 8 15 24 42 54 89 RFH-2 16 4 7 12 20 35 46 75 SF-2, 18 6 11 19 30 53 69 113 5FF-2 16 5 9 15 25 44 57 93 14 4 7 12 20 35 46 75 SF-1, 18 11 19 33 53 94 122 199 5FF-I RFH-1, 1$ 8 14 24 39 69 90 147 RFHH-2, TF,TFF, XF,XFF RFHH-2, 16 7 11 20 32 56 72 119 TF,TFF, XF, XFF XF, XFF 14 5 9 15 25 44 57 93 TI-N, 18 14 23 39 63 111 144 236 TFFN 16 10 17 30 48 85 110 180 74-726 NATIONAL ELECTRICAL CODE 2008 Edition ANNEX C Annex C: Tables Table C.5 Continued FIXTURE WIRIE,S Conductor Metric Designator(Trade Size) Size (AWGI 12 16 21 27 35 41 53 Type kcmil) ('/e) (1/2) ('/4) (1) (11/4) (11/2) (2) PF, PFF. 18 13 21 37 60 105 136 223 PGR PGFF,PAR 16 10 16 29 46 81 105 173 PAF PTFR 14 7 12 21 35 61 79 129 HF,HFR 18 17 28 48 77 136 176 288 ZF,ZFF, 16 12 20 35 57 100 129 212 ZHF 14 9 15 26 42 73 95 156 KF-2, 18 24 40 70 112 197 255 418 KFF-2 16 17 28 49 79 139 180 295 14 12 19 34 54 95 123 202 12 8 13 23 37 65 85 139 to 5 9 15 25 44 57 93 KF-1, 18 29 48 83 134 235 304 499 KFF-I 16 20 34 58 94 165 214 350 14 14 23 39 63 111 144 236 12 9 15 26 42 73 95 156 10 6 10 17 27 48 62 102 XF,XFF 12 3 5 8 13 23 30 50 10 1 3 6 10 18 23 39 Notes: I.This table is for concentric stranded conductors only. For compact stranded conductors,Table CS(A) should be used. 2.Two-hour fire-rated RHH cable has ceramifiable insulation which has much larger diameters than other RHH wires. Consult manufacturer's conduit fill tables, Corresponds to 356.2(2). 'Types RHH, RHW, and RHW-2 without outer covering. 2008 Edition NATIONAL ELECTRICAL CODE 70--727 Annex C: Tables ANNEX C Table C.5(A) Maximum Number of Compact Conductors in Liquidtight Flexible Nonmetallic Conduit (Type LFNC-B*) (Based on Table 1, Chapter 9) COMPACT CONDUCTORS Conductor Metric Designator(Trade Size) Size (AW GI 12 16 21 27 35 41 53 Type kcmil) (3/8) (c/x) (314) (1) (1c/4) (1112) (2) THW, 8 1 2 4 7 12 15 25 THW-2, 6 1 3 5 9 12 19 THHW 4 1 2 4 7 9 14 2 1 l 3 5 6 11 l U 1 l 1 3 4 7 110 0 1 1 1 3 4 6 210 0 0 1 1 2 3 5 310 0 0 1 1 1 3 4 410 1 0 0 l 1 l 2 4 250 0 0 U 1 l 1 3 300 0 0 0 1 1 1 2 350 0 0 0 1 I 1 2 400 0 U 0 0 1 1 1 500 0 0 0 0 1 1 1 600 0 0 0 0 t 1 1 700 U 0 0 U 1 1 1 750 0 0 0 0 0 1 1 900 — U 0 0 0 1 1 1000 0 U U 0 0 1 l THHN, 8 — — — --- — — THWN, 6 1 2 4 7 13 17 28 THWN-2 4 1 1 3 4 8 11 17 2 1 l 1 3 6 7 12 1 0 l 1 2 4 6 9 1l0 0 l 1 l 4 5 8 210 0 l 1 l 3 4 6 310 U 0 1 l 2 3 5 410 1 0 0 1 l 1 3 4 250 0 0 1 1 1 1 3 300 0 0 0 l 1 1 3 350 U 0 0 l 1 1 2 400 0 0 0 1 1 1 2 500 0 0 0 0 1 1 1 600 0 0 0 U 1 1 1 700 U 0 0 0 1 1 1 750 0 0 0 0 1 1 1 900 — 0 0 0 0 1 1 11x10 0 0 0 0 0 1 1 XHHW, 8 1 3 5 1) 15 20 33 XHHW-2 6 1 2 4 6 11 15 24 4 1 1 3 4 8 11 17 2 1 1 1 3 6 7 12 1 0 1 1 2 4 6 9 110 U 1 1 1 4 5 8 210 0 l 1 1 3 4 7 310 0 0 1 1 2 3 5 410 1 0 0 1 1 1 3 4 250 U 0 1 1 1 1 3 300 0 0 0 1 1 1 3 350 0 0 0 1 1 l 3 401) 0 0 0 1 1 l 2 500 0 0 0 0 1 l l 600 0 0 0 0 1 1 1 700 0 0 0 0 1 1 1 750 0 0 0 0 1 1 1 900 — 0 U 0 0 1 1 1000 1 0 0 0 0 0 1 1 Corresponds to 356.2(2). Definition: Compact stranding is the result of a manufacturing process where the standard conductor is compressed to the extent that the interstices(voids between strand wires) are virtually eliminated. 70-728 NATIONAL ELECTRICAL CODE 2008 Edition ANNEX C Annex C: Tables Table C.6 Maximum Number of Conductors or Fixture Wires in Liquidtight Flexible Nonmetallic Conduit(Type LFNC-A*) (Based on Table I, Chapter 9) CONDUCTORS Conductor Metric Designator(Trade Size) Size (AWG/ 12 16 21 27 35 41 53 Type kcmil) ('/R) ('/2J (`14) (t) (1'14) (11!2) (2) RHH, 14 2 4 7 11 20 27 45 RHW, 12 I 3 6 9 17 23 38 RHW-2 10 3 5 8 13 18 30 8 1 2 4 7 9 16 6 1 1 3 5 7 13 4 0 1 1 2 4 6 10 3 0 l 1 1 4 5 8 2 0 1 I 1 3 4 7 1 0 0 9 1 l 3 5 110 0 0 1 1 1 2 4 210 0 0 1 1 1 1 4 310 0 0 0 1 l 1 3 410 0 0 0 1 1 1 3 250 0 0 0 0 1 1 1 300 0 0 0 0 l 1 1 350 0 0 0 0 1 1 1 400 0 0 0 0 1 1 1 500 0 0 0 0 0 1 1 600 0 0 0 0 0 1 1 700 0 0 0 0 0 0 1 750 0 0 0 0 0 0 1 800 0 0 0 0 0 0 1 900 0 0 0 0 0 0 1 1000 0 0 0 0 0 0 1 1250 0 0 0 0 0 0 0 1500 0 0 0 0 0 0 0 1750 0 0 0 0 0 0 0 2000 0 0 0 0 0 0 0 TW 14 5 9 15 24 43 58 96 12 4 7 12 19 33 44 74 10 3 5 9 14 24 33 55 8 1 3 5 8 13 18 30 RHH', 14 3 6 10 16 28 38 64 RHW', RHW-2', THHW, THW, THW-2 RHH', 12 3 4 8 13 23 31 51 RHW , RHW-2 , 10 1 3 6 10 18 24 40 THHW, THW RHH', 8 1 1 4 6 l0 14 24 RHW , RHW-2 THHW, THW. THW-2 1Confinnes) 2008 Edition NATIONAL ELECTRICAL COPE 70-729 Annex C: Tables ANNEX C Table C.6 Continued CONDUCTORS Conductor Metric Designator(Trade Size) Size (AWG/ 12 16 21 27 35 41 53 Type kcmil) ('/a) ('/2) ('14) (1) (11/r) (11/2) (2) RHH'. 6 1 3 4 8 11 18 RHW`, 4 1 1 l 3 6 8 13 RHW-2'. 3 p 1 3 5 7 11 TW 2 0 1 l 2 4 6 10 THW, 1 0 1 1 1 3 4 7 THHW, UO (1 0 l 1 2 3 6 THW-2 2/0 (1 0 l 1 1 3 5 310 (1 {} l 1 1 2 4 410 0 0 U 1 l 1 3 250 0 0 U 1 l 1 3 300 0 0 0 1 1 l 2 350 0 {] 0 0 1 1 1 400 0 0 (1 0 1 1 1 500 0 0 0 0 1 1 1 600 (1 O D 0 1 1 1 700 n 0 D 0 0 1 1 750 n n D 0 D 1 1 80{) U 0 {} 0 0 1 1 900 U 0 0 0 0 0 1 1000 U 0 0 0 0 0 1 1250 (1 0 0 0 0 0 1 1500 (1 f) U 0 0 0 1 1750 0 0 0 0 U 0 0 2000 0 0 0 0 0 0 O THHN, 14 8 13 22 35 62 83 137 THWN, 12 5 9 16 25 45 60 100 THWN-2 10 3 6 10 16 28 38 63 R 3 6 9 16 22 36 (1 2 4 6 12 16 26 4 1 2 4 7 9 16 3 1 1 3 6 8 13 2 1 1 3 5 7 11 l U 1 1 1 4 5 8 1/0 0 1 1 1 3 4 7 210 0 U 1 1 2 3 6 310 0 0 1 1 1 3 5 410 (1 0 1 1 1 2 4 250 0 0 0 1 1 1 3 300 0 0 0 1 1 1 3 350 0 0 0 1 1 1 2 400 0 D 0 D 1 1 1 500 U 0 0 D 1 1 1 600 0 0 0 0 1 1 1 700 0 0 U 0 1 1 1 750 0 0 0 0 U 1 1 Soo 0 0 0 0 0 1 1 900 0 0 0 0 0 1 1 1000 0 U 0 0 0 0 1 FEP. 14 7 12 2I 34 60 80 133 FEP6, 12 5 9 15 25 44 59 97 PFA, 10 4 6 11 18 31 42 70 PFAH. 8 3 6 10 18 24 40 TFE 6 2 4 7 13 17 28 4 1 3 5 9 12 20 3 1 2 4 7 10 16 2 1 1 3 6 8 13 70-730 NATIONAL ELECTRICAL CODE 2008 Edition ANNEX C Annex C:Tables Table C.6 Continued CONDUCTORS Conductor Metric Designator('Dade Size) Size (AWG/ 12 16 21 27 35 41 53 Type kemil) ('/a) {[h) (ifs) (1) (11/4) (11/2) (2) PFA, 1 1) 1 1 2 4 5 9 PFAH, TFE PFA, 110 0 1 1 1 3 5 8 PFAH, 2/0 0 1 1 1 3 4 6 TFE,Z 3A) (l 0 1 1 2 3 5 4/0 0 {) 1 1 1 2 4 Z 14 9 15 25 41 72 97 161 12 6 10 18 29 51 69 114 W 4 6 11 18 31 42 70 8 2 4 7 11 20 26 44 6 l 3 5 8 14 18 31 4 l 1 3 5 9 13 2P 3 l 1 2 4 7 9 15 2 1 1 1 3 6 8 13 1 1 1 1 2 4 6 10 XHH. 14 5 9 15 24 43 58 96 XHHW, 12 4 7 12 19 33 44 74 XHHW-2. 10 5 9 14 24 33 55 ZW 8 ) 3 5 8 13 18 30 6 1 1 3 5 10 13 22 4 1 1 2 4 7 10 16 3 1 1 l 3 6 8 14 2 1 l 1 3 5 7 11 XHH, 1 0 1 1 1 4 5 8 XHHW, 1/0 0 l l 3 4 7 XHHW-2 210 0 0 l 2 3 6 310 0 0 l 1 3 5 410 0 0 1 1 2 4 250 0 0 0 1 1 1 3 300 0 0 0 1 1 1 3 350 0 0 0 1 l 1 2 400 0 0 0 0 1 1 1 500 0 0 0 0 1 1 1 600 0 0 0 0 1 1 1 700 0 0 0 0 1 1 1 750 0 0 0 0 0 1 1 800 0 0 0 0 0 1 1 900 0 0 0 0 0 1 1 11100 0 0 0 0 0 0 1 1250 0 0 0 0 0 0 1 1500 0 0 0 0 0 0 1 1750 0 0 0 0 0 0 0 2000 0 0 0 0 0 0 0 (Continues) 2008 Edition NATIONAL ELECTRICAL CODE 70_731 Annex C: Tables ANNEX C Table C.6 Continued FIXTURE WIRES Conductor Metric Designator(Trade Size) Size (AWGI 12 16 21 27 35 41 53 "),pe kcmil) (3/e) (1/2) (;f,) (1) (11/a) (11/2) (2) FFH-2, 14 5 8 14 23 41 55 92 RFH-2, 16 4 7 12 20 35 47 77 RFHH-3 §F_2, 18 6 11 is 29 52 70 116 SFF-2 16 5 9 15 24 43 58 96 14 4 7 12 20 35 47 77 SF_1, 18 12 19 33 52 92 124 205 SFF-1 RFH-1, 18 8 14 24 39 68 91 152 RFHH-2, TF,TFF, XF,XFF RFHH-2, 16 7 11 19 31 55 74 122 TF.TFF, XF,XFF XF,XFF 14 5 9 15 24 43 58 96 TFN, 18 14 22 39 62 109 146 243 TFFN 16 l0 17 29 47 83 112 1 S5 PR PFF. 18 13 21 37 59 103 139 230 PG R PGFR 16 l0 16 28 45 80 107 178 PAF,PTF, PTFF, 14 7 12 21 34 60 80 133 PAFF HF, HFF, 18 17 27 47 76 133 179 297 ZF ZFF. 16 12 20 35 56 98 132 2I9 ZHF 14 9 15 25 41 72 97 1()l KF-2, 18 25 40 69 Ii0 193 260 431 KFF-2 16 17 28 48 77 136 183 303 14 12 19 33 53 94 126 209 12 8 13 23 36 64 86 143 10 5 9 15 24 43 58 96 KF-1. 18 29 48 82 131 231 310 514 KFF-1 16 21 33 57 92 162 218 361 14 14 22 39 62 109 146 243 12 9 15 25 41 72 97 16l 10 6 10 17 27 47 63 105 XF, XFF 12 3 4 8 13 23 31 51 10 1 3 6 10 18 24 40 Notes: 1.This table is for concentric stranded conductors only. For compact stranded conductors,Table C.6(A) should be used. 2.Two-hour fire-rated RHH cable has ceramifiable insulation which has much larger diameters than other RHH wires.Consult manufacturer's conduit fill tables. 'Corresponds to 356.2(1), 'Types RHH, RHW, and RHW-2 without outer covering. 70--732 NATIONAL ELECTRICAL CODE 2008 Edition ANNEX C Annex C: Tables Table CMA) Maximum Number of Compact Conductors in Liquidtight Flexible Nonmetallic Conduit(Type LFNC-A*) (Based on Table I, Chapter 9) COMPACT CONDUCTORS Conductor Metric Designator(Trade Size) Size (ANVG1 12 16 21 27 35 41 53 ,W Pe kcmil) 0/4) (1/2) 014) (1) (11/4) (11/2) (2) THW, 8 l 2 4 6 11 16 26 THW-2, 6 1 l 3 5 9 12 20 THHW 4 l l 2 4 7 9 15 2 l l 1 3 5 6 11 1 U l 1 1 3 4 8 UU 0 l l 1 3 4 7 210 U U l 1 2 3 5 3/0 U 0 l 1 1 3 5 4/0 1 U 0 l 1 1 2 4 250 0 0 0 1 1 1 3 3(x1 0 0 0 1 1 1 3 350 U 0 U 1 1 1 2 400 0 0 0 0 1 1 1 5(x) 0 U 0 U 1 l 1 600 0 0 0 0 1 1 1 700 0 0 0 0 1 1 1 750 U 0 0 0 0 1 1 (M) — 0 0 0 U 1 1 I U00 U 0 0 0 0 l 1 THHN. 8 — — — — — — THWN, 6 I 2 4 7 13 18 29 THWN-2 4 1 1 3 4 8 11 18 2 1 l l 3 6 8 13 1 0 l 1 2 4 6 10 110 0 l l 1 3 5 8 210 0 l 1 1 3 4 7 310 0 U l 1 2 3 6 410 1 0 0 1 1 l 3 5 250 0 0 l 1 1 1 3 300 0 0 0 1 l 1 3 350 0 0 0 1 1 1 3 400 0 0 0 1 1 1 2 500 0 0 U 0 1 1 1 600 U (1 U U 1 1 700 0 0 0 0 1 1 750 U U U U 1 1 900 — 0 0 0 0 1 1000 U 0 U U 0 1 XHHW, 8 1 3 5 8 15 20 34 XHHW-2 6 1 2 4 6 11 15 25 4 1 l 3 4 8 II 18 2 1 1 1 3 6 8 13 1 0 l I 2 4 6 10 1/0 0 1 1 l 3 5 8 2/0 0 l 1 3 4 7 310 0 0 l 2 3 6 4/0 0 0 1 1 3 5 250 0 0 l 1 2 4 300 0 0 0 l 1 1 3 350 0 U 0 1 1 1 3 400 U U 0 l 1 1 2 500 0 0 0 0 1 1 1 600 0 0 0 0 1 1 l 700 0 0 0 U 1 I 1 750 U 0 0 0 1 1 l 900 — 0 0 0 0 1 l 1000 1 0 U 0 0 0 1 1 Corresponds to 356.2(1). Definition: Compact stranding is the result of a manufacturing process where the standard conductor is compressed to the extent that the interstices (voids between strand wires)are virtually eliminated. 2008 Edition NATIONAL ELECTRICAL CODE 70-733 Annex C: Tables ANNEX C Table C.7 Maximum Number or Conductors or Fixture Wires in Liquidtight Flexible Metal Conduit (LFMC) (Based on Table 1, Chapter 9) CONDUCTORS Conductor Metric Designator(Trade Size) Size (AWGI 16 21 27 35 41 53 63 78 91 103 Type kcmil) (1/11) ('/a) (1) (11/4) (11/2} (2) (2`h) (3) (31/2) (4) RHH, 14 4 7 12 21 27 44 66 102 133 173 RHW. 12 3 6 10 17 22 36 55 84 110 144 RHW-2 10 3 5 8 14 18 29 44 68 89 116 8 1 2 4 7 9 15 23 36 46 61 6 1 l 3 6 7 12 18 28 37 48 4 1 l 2 4 6 9 14 22 29 38 3 1 l 1 4 5 8 13 19 25 33 2 1 l 1 3 4 7 11 17 22 29 l 0 l 1 1 3 5 7 11 14 19 1/0 0 l 1 1 2 4 6 10 13 16 210 0 1 1 1 3 5 8 11 14 310 {} 0 1 1 3 4 7 9 12 410 0 0 1 1 2 4 6 8 10 250 0 0 0 1 1 1 3 4 6 8 300 0 0 0 1 1 1 2 4 5 7 350 0 0 0 1 1 1 2 3 5 6 400 0 0 0 1 1 1 1 3 4 6 500 0 0 0 1 1 1 1 3 4 5 600 0 0 0 0 1 1 1 2 3 4 700 0 0 0 0 0 1 1 1 3 3 750 0 0 0 0 0 1 1 1 2 3 800 0 0 0 0 0 1 1 1 2 3 900 0 0 0 0 0 1 1 1 2 3 1000 0 0 0 1 l 3 1250 {} 0 0 0 0 0 1 1 l 1 1500 0 0 0 0 0 0 1 1 1 1 1750 0 0 0 0 0 0 1 1 1 1 2000 0 0 0 0 0 0 0 1 1 1 TW 14 9 15 25 44 57 93 140 215 280 365 12 7 12 19 33 43 1 108 165 215 280 10 5 9 14 25 32 53 80 123 160 209 8 3 5 8 14 18 29 44 68 89 116 RHH*. 14 6 10 16 29 38 62 93 143 186 243 RHW*, RHW-2*. THHW, THW, THW-2 RHH*, 12 5 8 13 23 30 50 75 115 149 195 RHW*, RHW-2*, 10 3 6 to l8 23 39 58 89 117 152 THHW, THW RHH*, 8 1 4 6 11 14 23 35 53 70 91 RHW*, RHW-2*, THHW, THW, THW-2 70-734 NATIONAL ELECTRICAL.CODE 2009 Edition ANNEX C Annex C: Tables Table C.7 Continued CONDUCTORS Conductor Metric Designator(Trade Size) Size (AWGI I6 21 27 35 41 53 63 78 91 103 Type kcmil) (1/2) (•Yr) (1) (1114) (11/2) (2) (2I/x) (3) (31/z) (4) RHH*, 6 1 3 5 8 11 18 27 41 53 70 RHW*, 4 1 1 3 6 8 13 20 30 40 52 RHW-2*, 3 1 1 3 5 7 11 17 26 34 44 TW� 2 1 1 2 4 6 9 14 22 29 38 THW, I I 1 1 3 4 7 10 15 20 26 THHW, 110 0 1 1 2 3 6 8 13 17 23 THW-2-2 210 0 1 1 2 3 5 7 11 15 19 310 0 1 1 l 2 4 6 9 12 16 410 0 0 1 l 1 3 5 8 10 13 250 0 0 1 l 1 3 4 6 8 11 300 0 0 1 1 1 2 3 5 7 9 350 0 (} 0 l 1 l 3 5 6 8 400 0 0 0 1 1 l 3 4 6 7 500 0 D 0 l l l 2 3 5 6 600 0 0 0 l l l l 3 4 5 700 0 0 (} 0 1 1 1 2 3 4 750 0 0 0 0 1 l 1 2 3 4 800 0 0 0 0 l l 1 2 3 4 900 0 0 0 0 0 l l 1 3 3 1000 (1 0 0 0 0 l l 1 2 3 1250 0 0 0 0 0 l l 1 1 2 1500 0 0 0 0 0 0 l 1 1 2 1750 0 0 (} 0 0 0 1 1 1 1 2000 0 0 0 0 0 0 l 1 1 1 THHN. 14 13 22 36 63 81 133 201 308 401 523 THWN, 12 9 16 26 46 59 97 146 225 292 381 THWN-2 10 6 10 16 29 37 61 92 141 184 240 8 3 6 9 16 21 35 53 81 106 138 6 2 4 7 12 15 25 38 59 76 100 4 1 2 4 7 9 IS 23 36 47 61 3 1 1 3 6 8 13 20 30 40 52 2 1 1 3 5 7 11 17 26 33 44 1 l 1 1 4 5 8 12 19 25 32 llO l 1 1 3 4 7 10 16 21 27 210 0 1 1 2 3 6 8 13 17 23 310 0 1 1 1 3 5 7 11 14 19 410 0 1 1 1 2 4 6 9 12 15 250 0 0 1 1 1 3 5 7 10 12 300 0 0 1 1 1 3 4 6 8 11 350 0 0 1 1 1 2 3 5 7 9 400 0 0 0 1 1 1 3 5 6 8 500 0 0 0 1 1 1 2 4 5 7 600 0 0 0 1 1 1 1 3 4 6 700 0 0 0 1 1 1 1 3 4 5 750 0 0 0 0 1 1 1 3 3 5 800 0 0 0 0 1 1 1 2 3 4 900 0 0 0 0 1 1 1 2 3 4 1000 0 0 0 0 0 1 I 1 3 3 FEP, 14 12 21 35 61 79 129 195 299 389 507 F'EPB, 12 9 15 25 44 57 94 142 218 284 370 PFA, 10 6 11 18 32 41 68 102 156 203 266 PFAH, 9 3 6 10 18 23 39 58 89 117 152 TFE 6 2 4 7 13 17 27 41 64 83 108 4 1 3 5 9 12 19 29 44 58 75 3 1 2 4 7 ]0 16 24 37 48 63 2 1 1 3 6 8 13 20 30 40 52 {Conrinuesl 2008 Edition NATIONAL ELECTRICAL CODE 70-735 Annex C: Tables ANNEX C Table C.7 Continued CONDUCTORS Conductor Metric Designator(Trade Size) Size (A\4'G/ 16 21 27 35 41 53 63 78 91 103 Type kcmil) (t/2) (1/4) (1) (1114) (1'x) (2) (21/2) (3) (31/2) (4) PFA, I 1 1 2 4 5 9 14 21 28 36 PFAH. TFE PFA, 1/0 1 l 3 4 7 11 18 23 30 PFAH, 210 1 l 3 4 6 9 14 19 25 TFE,Z 310 0 1 l 2 3 5 8 12 16 20 410 0 1 1 l 2 4 6 10 13 17 Z 14 20 26 42 73 95 156 235 360 469 611 12 14 18 30 52 67 111 167 255 332 434 10 8 II 18 32 41 68 102 156 203 266 8 5 7 11 20 26 43 64 99 129 168 6 4 5 8 14 18 30 45 69 90 118 4 2 3 5 9 12 20 31 48 62 81 3 2 2 4 7 9 15 23 35 45 59 2 1 1 3 6 7 12 19 29 38 49 i 1 1 2 5 6 10 15 23 30 40 XHH, 14 9 15 25 44 57 93 140 215 280 365 XHHW, 12 7 12 19 33 43 71 108 165 215 280 XHHW-2, 10 5 9 14 25 32 53 80 123 160 209 Zw 8 3 5 8 14 18 29 44 68 89 116 6 1 3 6 In 13 22 33 50 66 86 4 1 2 4 7 9 16 24 36 48 62 3 1 1 3 6 8 13 20 31 40 52 2 1 1 3 5 7 lI 17 26 34 44 1 1 1 1 4 5 8 12 19 25 33 XHH, 1/{} I 1 1 3 4 7 10 16 21 28 XHHW, 21(} 0 1 1 2 3 6 9 13 17 23 XH14W-2 310 0 1 1 1 3 5 7 Il 14 19 4/0 0 1 1 1 2 4 6 9 12 16 250 0 0 1 1 l 3 5 7 10 13 300 0 0 1 1 1 3 4 6 8 11 350 0 0 1 1 l 2 3 5 7 10 400 0 0 0 1 l 1 3 5 6 8 501 0 0 0 1 l 1 2 4 5 7 600 0 0 0 1 l 1 1 3 4 6 700 0 0 0 1 l 1 1 3 4 5 750 0 0 0 0 l 1 1 3 3 5 80(} n 0 0 0 l 1 1 2 3 4 goo 0 0 0 0 l 1 1 2 3 4 11M 0 0 0 1250 0 0 0 n 0 1 1 1 3 1500 0 0 0 0 0 l 1 2 1750 0 0 0 0 n n 1 2 20()0 0 0 0 0 0 0 1 1 2 70-736 NATIONAL ELECTRICAL CODE 2008 Edition ANNEX C Annex C: Tables Table C.7 Continued FIXTURE WIRES Conductor Metric Designator(Trade Size) Size (AWG/ 16 21 27 35 41 53 Type kcmil) (1/2) (-5/a) (1) (11/4) (11/x) (2) FFH-2, 18 8 15 24 42 54 89 RFH-2, 16 7 12 20 35 46 75 RFHH-3 SF-2, SFF-2 18 11 19 30 53 69 113 16 9 15 25 44 57 93 14 7 12 20 35 46 75 SF-1,SFF-1 18 19 33 53 94 122 199 RFH-1, 18 14 24 39 69 90 147 RFHH-2,TF, TFF,XF, XFF RFHH-2.TF, 1fi 11 20 32 56 72 119 TFF,XF, XFF XF,XFF 14 9 15 25 44 57 93 TFN,TFFN 18 23 39 63 111 144 236 16 17 30 48 85 110 180 PF, PFF, 18 21 37 60 105 136 223 PGF, PGFF, 16 16 29 46 81 105 173 PAR PTF, PTFF. PAFF 14 12 21 35 61 79 129 HF, HFF, I8 28 48 77 136 176 288 ZF,ZFF, 16 20 35 57 100 129 212 ZHF 14 15 26 42 73 95 156 KF-2, KFF-2 l8 40 70 112 197 255 418 16 28 49 79 139 180 295 14 19 34 54 95 123 202 12 13 23 37 65 85 139 10 9 15 25 44 57 93 KF-1, KFF-1 18 48 83 134 235 304 499 16 34 58 94 165 214 350 14 23 39 63 111 144 236 12 15 26 42 73 95 156 111 10 i 7 27 48 62 102 XF, XFF 12 5 8 13 23 30 50 ]0 3 6 10 18 23 39 Notes: I.This table is for concentric stranded conductors only. For compact stranded conductors,Table C.7(A) should be used. 2.Two-hour fire-rated RHH cable has ceramiliable insulation which has much larger diameters than other RHH wires. Consult manufacturer's conduit fill tables. Types RHH, RHW, and RHW-2 without outer covering. 2008 Edition NATIONAL ELECTRICAL CODE 70-737 Annex C: Tables ANNEX C Table CMA) Maximum Number of Compact Conductors in Liquidtight Flexible Metal Conduit (LFMC) (Based on Table 1, Chapter 9) COMPACT CONDUCTORS Conductor Metric Designator(Trade Size) Size (ANVG/ 12 16 21 27 35 41 53 63 78 91 103 Tv a kcmil) ('/x) (1/2) (1!4) (1) (11/a) (11/2) (2) (21/2) (3) (31/2) (4) THW, 8 1 2 4 7 12 15 25 38 58 76 99 THW-2, 6 1 1 3 5 9 12 19 29 4i 59 77 THHW 4 1 1 2 4 7 9 14 22 34 44 57 2 1 1 l 3 5 6 11 16 25 32 42 1 0 1 1 1 3 4 7 11 17 23 30 110 0 1 l 1 3 4 6 10 15 20 26 2/0 0 0 1 1 2 3 5 8 13 16 21 3I0 0 0 1 1 1 3 4 7 11 14 18 4/0 0 0 1 1 1 2 4 6 9 12 15 250 0 0 0 1 1 1 3 4 7 9 12 300 0 0 0 1 1 1 2 4 6 8 10 350 0 0 0 1 1 1 2 3 5 7 9 400 0 0 0 0 1 1 1 3 5 6 8 500 0 0 0 0 1 1 1 3 4 1 7 600 0 0 0 0 1 l 1 l 3 4 6 700 0 0 0 0 1 1 1 1 3 4 5 750 0 0 0 0 0 l 1 1 3 3 5 900 — 0 0 0 0 l 1 1 2 3 4 1000 0 0 0 0 0 l 1 1 1 3 4 THHN, 8 — — — — — — — — — — — THWN, 6 1 2 4 7 13 17 28 43 66 86 112 THWN-2 4 1 1 3 4 8 11 17 26 41 53 69 2 l 1 3 6 7 12 19 29 38 50 1 0 1 2 4 6 9 14 22 28 37 1/0 0 1 1 l 4 5 8 12 19 24 32 210 0 1 l 3 4 6 l0 15 20 26 310 0 0 1 l 2 3 5 8 13 17 22 410 0 0 1 1 l 3 4 7 10 14 18 250 0 0 1 I 1 1 3 5 8 11 14 300 0 0 0 1 1 1 3 4 7 9 12 350 0 0 0 1 1 1 2 4 6 8 11 400 0 0 0 1 1 1 2 3 5 7 9 500 0 0 0 0 1 1 1 3 5 6 8 600 0 0 0 0 1 1 1 2 4 5 6 700 0 0 0 0 1 1 1 t 3 4 6 750 0 0 0 0 1 1 1 1 3 4 5 900 — 0 0 0 0 1 1 1 2 3 4 1000 0 0 0 0 0 l 1 1 2 3 4 XHHW, 8 l 3 5 9 15 20 33 49 76 98 129 XHHW-2 6 l 2 4 6 11 15 24 37 56 73 95 4 l 1 3 4 8 11 17 26 41 53 69 2 l 1 1 3 6 7 12 19 29 38 50 1 0 1 1 2 4 6 9 14 22 28 37 110 0 1 1 1 4 5 8 12 19 24 32 210 0 1 1 1 3 4 7 10 16 20 27 310 0 0 1 1 2 3 5 8 13 17 22 410 0 0 1 1 l 3 4 7 11 14 18 250 0 0 1 l l 1 3 5 8 11 15 300 0 0 0 l l 1 3 5 7 9 12 350 0 0 0 1 l 1 3 4 6 8 11 400 0 0 0 l l 1 2 4 6 7 10 500 0 0 0 0 1 1 1 3 5 6 8 600 0 0 0 0 1 1 1 2 4 5 6 700 0 0 0 0 1 1 1 1 3 4 6 750 0 0 0 0 1 1 1 1 3 4 5 900 0 0 0 0 1 1 2 2 3 4 1000 0 0 0 0 0 1 1 1 2 3 4 Definition: Compact stranding is the result of a manufacturing process where the standard conductor is compressed to the extent that the interstices (voids between strand wires) are virtually eliminated. 70-738 NATIONAL ELECTRICAL CODE 2008 Edition ANNEX C Annex C:Tables Table C.8 Maximum Number of Conductors or Fixture Wires in Rigid Metal Conduit(RMC) (Based on Table 1, Chapirr 9) CONDUCTORS Conductor Metric Designator('bade Size) Size (AWG/ 16 21 27 35 41 53 63 78 91 103 129 155 'lope kcmil) (1/2) (1/4) (1) (11/4) (11/2) (2) (21/2) (3) (31/2) (4) (5) (6) RHH, 14 4 7 12 21 28 46 66 102 136 176 276 398 RHW, 12 3 6 l0 17 23 38 55 85 113 146 229 330 RHW-2 10 3 5 8 14 19 31 44 68 91 118 185 267 8 1 2 4 7 10 16 23 36 48 61 97 139 6 1 l 3 6 8 13 18 29 38 49 77 112 4 1 l 2 4 6 10 14 22 30 38 60 87 3 1 l 2 4 5 9 12 19 26 34 53 76 2 1 l 1 3 4 7 11 17 23 29 46 66 1 0 l 1 1 3 5 7 11 15 19 30 44 110 0 l 1 1 2 4 6 10 13 17 26 38 210 0 l 1 1 2 4 5 8 11 14 23 33 310 0 0 1 1 l 3 4 7 10 12 20 28 410 {1 0 1 1 l 3 4 6 8 11 17 24 250 0 0 (1 1 l 1 3 4 6 8 13 18 300 0 0 ❑ 1 1 1 2 4 5 7 11 16 350 0 0 0 1 l 1 2 4 5 6 10 I5 400 0 0 0 1 l 1 1 3 4 6 9 13 500 0 0 0 1 l 1 1 3 4 5 8 11 600 0 0 U 0 l 1 1 2 3 4 6 9 700 0 0 0 0 l 1 1 1 3 4 6 8 750 (} 0 0 0 0 1 1 1 3 3 5 8 800 0 O 0 0 0 1 1 1 2 3 5 7 900 0 0 0 0 0 1 1 1 2 3 5 7 1000 0 0 0 0 0 1 1 1 1 3 4 6 1250 0 0 0 0 0 0 l 1 1 1 3 5 1500 0 0 0 0 0 0 l 1 1 1 3 4 1750 0 0 0 0 0 0 l 1 1 1 2 4 200() 0 0 0 0 0 0 0 1 1 1 2 3 TW 14 9 15 25 44 59 98 140 216 288 370 581 839 12 7 12 19 33 45 75 107 165 221 284 446 644 10 5 9 14 25 34 56 80 123 164 212 332 480 8 3 5 8 14 19 31 44 68 91 118 185 267 RHH', 14 (1 10 17 29 39 65 93 143 191 246 387 558 RHW*, RHW-2* THHW, THW, THW-2 RHH*, 12 5 8 13 23 32 52 75 115 154 198 311 448 RHW*, RHW 2*, 10 3 6 10 18 25 41 58 90 120 154 242 350 THHW, THW RHH*, 8 1 4 6 11 15 24 35 54 72 92 145 209 RHW*, RII W-2*, THHW, THW, THW-2 Won irmes) 2008 Edition NATIONAL ELECTRICAL CODE 70-739 Annex C: Tables ANNEX C Table C.8 Continued CONDUCTORS Conductor Metric Designator(Trade Size) Size WVG/ 16 21 27 35 41 53 63 78 91 103 129 155 Type kcmil) (1/2) 0/0 (1) (1114) (1 IN (2) (21/2) (3) (3 Vi) (4) (5) (6) RHH*. 6 1 3 5 8 11 18 27 41 55 71 111 160 RHW*- 4 1 1 3 6 8 14 20 31 41 53 83 120 RHW-2*. 3 1 1 3 5 7 12 17 26 35 45 71 103 TW 2 1 I 2 4 6 IU 14 22 30 38 60 87 THW, 1 1 1 1 3 4 7 10 15 21 27 42 61 THHW, 1/0 0 I 1 2 3 6 8 13 18 23 36 52 THW-2 2/0 0 I 1 2 3 5 7 11 15 19 31 44 3/0 U 1 1 l 2 4 6 9 13 16 26 37 4/0 U U 1 l 1 3 5 8 10 14 21 31 250 U 0 1 l 1 3 4 6 8 11 17 25 300 0 0 1 l 1 2 3 5 7 9 15 22 350 0 0 0 1 1 1 3 5 6 8 13 19 400 {) 0 0 l 1 1 3 4 6 7 12 17 500 0 0 0 l 1 l 2 3 5 6 10 14 600 0 U 0 l 1 1 1 3 4 5 8 12 700 0 U 0 0 1 l 1 2 3 4 7 10 750 {) 0 0 0 1 1 1 2 3 4 7 10 800 0 0 0 0 1 l 1 2 3 4 6 9 900 0 0 0 U 1 l 1 l 3 4 6 8 100{) {} 0 0 0 0 l 1 l 2 3 5 8 1250 0 U 0 0 0 l 1 I 1 2 4 6 1500 0 U 0 0 0 l 1 1 1 2 3 5 1750 0 0 0 0 0 0 1 1 1 l 3 4 2000 {} 0 0 0 0 0 1 1 1 1 3 4 TH HN. 14 13 22 36 63 85 140 200 309 412 531 833 1202 THWN, 12 9 16 26 46 62 102 146 225 301 387 608 877 THWN-2 10 6 10 17 29 39 64 92 142 189 244 383 552 8 3 6 9 16 22 37 53 82 109 140 221 318 6 2 4 7 12 16 27 38 59 79 101 159 230 4 1 2 4 7 10 16 23 36 48 62 98 141 3 1 l 3 6 8 14 20 31 41 53 83 120 2 1 l 3 5 7 11 17 26 34 44 70 100 I I l 1 4 5 8 12 19 25 33 51 74 1/0 1 1 1 3 4 7 10 16 21 27 43 63 2/0 U 1 1 2 3 6 8 13 18 23 36 52 310 0 I 1 1 3 5 7 11 15 19 30 43 410 0 1 1 1 2 4 6 9 12 16 25 36 250 0 0 1 1 l 3 5 7 10 13 20 29 300 0 0 1 1 1 3 4 6 8 11 17 25 350 0 0 1 1 1 2 3 5 7 10 15 22 400 0 0 1 1 l 2 3 5 7 8 13 20 500 0 0 0 1 l 1 2 4 5 7 11 16 600 0 0 0 1 1 1 1 3 4 6 9 13 700 0 0 0 1 1 1 1 3 4 5 8 11 750 0 0 0 0 1 1 1 3 4 5 7 11 800 0 0 0 0 1 1 1 2 3 4 7 10 900 0 0 0 0 1 1 1 2 3 4 6 9 1000 0 0 0 0 1 1 1 1 3 4 6 8 FER 14 12 22 35 61 83 136 194 300 400 515 808 1166 FEPH, 12 9 16 26 44 60 99 142 219 292 376 590 851 PFA. 10 6 11 18 32 43 71 102 157 209 269 423 610 PFA H, 8 3 6 10 18 25 41 58 90 120 154 242 350 TFE 6 2 4 7 13 17 29 41 64 85 110 172 249 4 l 3 5 9 12 20 29 44 59 77 120 174 3 l 2 4 7 10 17 24 37 50 64 100 145 2 l 1 3 6 8 14 20 31 41 53 83 120 70-740 NATIONAL ELECTRICAL CODE 2008 Edition ANNEX C Annex C: Tables Table C.8 Continued CONDUCTORS Conductor Metric Designator(Trade Size) Size (AWG/ 16 21 27 35 41 53 63 78 91 103 129 155 TyPe kcmil) ('/2) (-/r) (l) (1114) (1'/2) (2) (21/2) (3) (31/2) (4) (5) (6) PFA, I l 1 2 4 6 9 14 21 28 37 57 83 PFAH, TFE PFA, 1/0 l 1 1 3 5 8 11 18 24 30 48 69 PFAH, 2/0 l 1 l 3 4 6 9 14 19 25 40 57 TFE,Z 3/0 0 1 l 2 3 5 8 12 16 21 33 47 410 0 1 l 1 2 4 6 10 13 17 27 39 Z 14 15 26 42 73 100 164 234 361 482 621 974 1405 12 10 18 30 52 71 116 166 256 342 440 691 997 10 6 11 18 32 43 71 102 157 209 269 423 610 8 4 7 11 2U 27 45 64 99 132 170 267 386 6 3 5 8 14 19 31 45 69 93 120 188 271 1 3 5 9 13 22 31 48 64 82 129 186 1 2 4 7 9 16 22 35 47 60 94 136 2 1 1 3 6 8 13 19 29 39 50 78 113 1 1 1 2 5 6 10 15 23 31 40 63 92 XHH, 14 9 15 25 44 59 98 140 216 288 370 581 839 XHHW, 12 7 12 19 33 45 75 107 165 221 284 446 644 XHHW-2 10 5 9 14 25 34 56 80 123 164 212 332 480 ZW 8 3 5 8 14 19 31 44 68 91 118 185 267 6 1 3 6 10 14 23 33 51 68 87 137 197 4 1 2 4 7 10 16 24 37 49 63 99 143 3 1 1 3 6 8 14 20 31 41 53 84 121 2 1 1 3 5 7 12 17 26 35 45 70 101 l 1 1 1 4 5 9 12 19 26 33 52 76 XHH, 110 1 1 1 3 4 7 10 16 22 28 44 64 XHHW, 210 0 1 1 2 3 6 9 13 18 23 37 53 XHHW-2 310 0 1 1 1 3 5 7 11 15 19 30 44 410 0 1 1 1 2 4 6 9 12 16 25 36 250 0 0 1 1 1 3 5 7 10 13 20 30 300 U 0 1 1 1 3 4 6 9 II IN 25 350 0 U 1 1 1 2 3 6 7 10 15 22 400 0 0 1 1 1 2 3 5 7 9 14 20 500 0 0 U 1 1 l 2 4 5 7 11 16 600 0 0 0 1 1 1 1 3 4 6 9 13 700 0 0 U 1 1 l l 3 4 5 8 11 750 0 0 0 0 1 l l 3 4 5 7 11 800 0 0 0 0 1 l l 2 3 4 7 10 900 0 0 0 0 1 l l 2 3 4 6 9 1000 0 0 0 0 1 1 l 1 3 4 6 8 1250 0 0 0 0 0 l l 1 2 3 4 6 1500 0 0 0 0 0 1 1 1 1 2 4 5 1750 0 0 U 0 0 0 l 1 l 1 3 5 2000 0 0 (1 0 0 0 l 1 1 1 3 4 (Confiiures) 2008 Edition NATIONAL ELECTRICAL CODE 70--741 Annex 0 Tables ANNEX C Table C.8 Continued FIXTURE WIRES Conductor Metric Designator(Trade Size) Size (AWGI 16 21 27 35 41 53 Type kemil) f`/2) 0/4) (1) (11/4) (11/2) (2) FFH-2, 18 8 15 24 42 57 94 RFH-2, 16 7 12 20 35 48 79 RFHH-3 SF-2,SFF-2 18 11 19 31 53 72 118 16 9 15 25 44 59 98 14 7 12 20 35 48 79 SF-1,SFF-1 18 19 33 54 94 127 209 RFH-1, 18 14 25 40 h() 94 155 RFHH-2,TF, T17R XF, XFF RFHH-2,TF, 16 11 20 32 56 76 125 TFR XF, XFF XR XFF 14 9 15 25 44 59 98 TFN,TFFN 18 23 40 64 111 150 248 16 17 30 49 84 115 189 PF,PFF, 18 21 38 61 105 143 235 PGF,PGFF, 16 16 29 47 81 110 181 PAF,PTI PTFF,PAFF 14 12 22 35 61 83 136 HF, HFF, 18 28 )3 ZF,ZFF, 16 20 36 58 100 136 223 ZHF 14 15 26 42 73 100 164 KF-2, KFF-2 18 40 71 114 197 267 439 16 28 50 80 138 188 310 14 19 34 55 95 129 213 12 13 23 38 65 89 146 10 9 15 25 44 59 98 KFA. KFF-1 18 48 84 136 235 318 524 16 34 59 96 165 224 3611 14 23 40 64 111 150 248 12 15 26 42 73 100 164 10 10 17 28 48 65 107 XF, XFF 12 5 32 52 10 3 6 10 18 25 41 Notes: 1.This table is For concentric stranded conductors only. For compact stranded conductors,Table C.8(A) should be used. 2.Two-hour fire-rated RHH cable has ceramifiable insulation which has much larger diameters than other RHH wires. Consult manufacturer'% conduit fill tables. *Types RHH, RHW, and RFIW-2 without outer covering. 70-742 NATIONAL ELECTRICAL CODE 2008 Edition ANNEX C Annex C: Tables Table C.8(A) Maximum Number of Compact Conductors in Rigid Metal Conduit (RMC) (Based on Table 1, Chapter 9) COMPACT CONDUCTORS Conductor Metric Designator(Trade Size) Size --—=- —_ (AWGI 16 21 27 35 41 53 63 78 91 103 129 155 ,v Pe kcmil) (1/2) ('/a) (1) (11 14) (lc/2) (2) (21/2) (3) (31/2) (4) (5) (6) THW, 8 2 4 7 12 16 26 38 59 78 101 158 228 THW-2, 6 i 3 5 9 12 20 29 45 60 78 122 176 THHW 4 2 4 7 9 15 22 34 45 58 91 132 2 1 3 5 7 11 16 25 33 43 67 97 l 1 1 3 5 8 11 17 23 30 47 68 110 1 1 l 3 4 7 10 15 20 26 41 59 210 0 1 l 2 3 6 8 13 17 22 34 50 310 0 1 l 1 3 5 7 11 14 19 29 42 410 0 1 l 1 2 4 6 9 12 15 24 35 250 0 0 l 1 l 3 4 7 9 12 19 28 300 0 0 l 1 l 3 4 6 8 11 17 24 350 0 0 l 1 l 2 3 5 7 9 15 22 400 0 0 l i l 1 3 5 7 8 13 20 500 0 0 0 1 l 1 3 4 5 7 11 17 600 0 0 0 1 l 1 1 3 4 6 9 13 700 0 0 0 i l 1 1 3 4 5 8 12 750 0 0 0 0 l 1 1 3 4 5 7 11 900 0 0 0 0 l 1 1 2 3 4 6 9 1000 0 0 0 0 l 1 1 1 3 4 6 9 THHN. 8 — — — — — — — — — — THWN, 6 2 5 8 13 18 30 43 66 88 114 179 258 THWN-2 4 1 3 5 8 11 18 26 41 55 70 110 159 2 i l 3 6 8 13 19 29 39 50 79 114 1 1 l 2 4 6 10 14 22 29 38 60 86 110 1 l l 4 5 8 12 19 25 32 51 73 210 1 l l 3 4 7 l0 15 21 26 42 60 310 0 l l 2 3 6 8 13 17 22 35 51 410 0 l l 1 3 5 7 10 14 18 29 42 250 0 l l 1 2 4 5 8 11 14 23 33 300 0 0 l 1 l 3 4 7 10 12 20 28 350 0 0 l 1 l 3 4 6 8 11 17 25 400 0 0 l 1 l 2 3 5 7 10 15 22 500 0 0 0 1 1 1 3 5 6 8 13 19 600 0 0 0 1 l 1 2 4 5 6 l0 15 700 0 0 0 1 l 1 1 3 4 6 9 13 750 0 0 0 1 l 1 1 3 4 5 9 13 900 0 0 0 0 l 1 1 2 3 4 6 9 1000 0 0 0 0 1 1 1 2 3 4 6 9 XHHW, 8 3 5 9 15 21 34 49 76 101 130 205 296 XHHW-2 6 2 4 6 11 15 25 36 56 75 97 152 220 4 3 5 8 11 18 26 41 55 70 110 159 2 1 3 6 8 13 19 29 39 50 79 114 1 1 2 4 6 10 14 22 29 38 60 86 1/0 1 1 1 4 5 8 12 19 25 32 51 73 210 1 1 1 3 4 7 l0 16 21 27 43 62 310 0 1 1 2 3 6 8 13 17 22 35 51 410 0 1 l 1 3 5 7 11 14 19 29 42 250 0 1 1 1 2 4 5 8 11 15 23 34 300 0 0 l 1 1 3 5 7 10 13 20 29 350 0 0 l 1 1 3 4 6 9 11 18 25 400 0 0 l 1 1 2 4 6 8 10 16 23 500 0 0 0 1 1 1 3 5 6 8 13 19 600 0 0 0 1 1 1 2 4 5 7 10 15 700 0 0 0 1 1 1 1 3 4 6 9 13 750 0 0 0 1 1 1 1 3 4 5 8 12 900 0 0 0 0 1 1 2 2 3 5 7 l0 1000 0 0 0 0 1 1 1 2 3 4 7 10 Definition: Compact stranding is the result of a manufacturing process where the standard conductor is compressed to the extent that (he interstices (voids between strand wires) are virtually eliminated. 2009 Edition NATIONAL ELECTRICAL CODE 70-743 Annex C: Tables ANNEX C Table C.9 Maximum Number of Conductors or Fixture Wires in Rigid PVC Conduit, Schedule 80 (Based on Ruble 1, Chapter 9) CONDUCTORS Conductor ;Metric Designator("Trade Size) Size (AWGI 16 21 27 35 41 53 63 78 91 103 129 155 Type kcmil) (1/2) 0/4) (1) (1114) (11/2) (2) (21/2) (3) (31/2) (4) (5) (6) RHH, 14 3 5 9 17 23 39 56 88 118 153 243 349 RHW, 12 2 4 7 14 19 32 46 73 98 127 202 290 RHW-2 10 1 3 6 11 15 26 37 59 79 103 163 234 8 1 1 3 6 8 13 19 31 41 54 85 122 6 1 l 2 4 6 11 16 24 33 43 68 98 4 1 l 1 3 5 8 12 19 26 33 53 77 3 0 l l 3 4 7 11 17 23 29 47 67 2 0 l l 3 4 6 9 14 20 25 41 58 1 0 1 1 1 2 4 6 9 13 17 27 38 110 0 0 1 l 1 3 5 8 11 15 23 33 210 0 0 l l 1 3 4 7 10 13 20 29 310 0 0 1 1 1 3 4 6 8 11 17 25 410 0 0 0 l 1 2 3 5 7 9 15 21 250 0 0 0 l 1 1 2 4 5 7 11 1 f 300 0 0 0 l 1 1 2 3 5 6 10 14 350 0 0 0 l 1 1 1 3 4 5 9 13 400 0 0 0 0 1 1 1 3 4 5 8 12 500 0 0 0 0 1 1 1 2 3 4 7 10 600 0 0 0 0 0 1 1 l 3 3 6 8 700 0 0 0 0 0 1 1 l 2 3 5 7 750 0 0 0 0 0 1 1 l 2 3 5 7 800 0 0 0 0 0 1 1 1 2 3 4 7 1000 0 0 0 0 0 1 l 1 l 2 4 5 1250 0 0 0 0 0 (i 1 1 l 1 3 4 1500 0 0 0 0 0 0 l 1 1 1 2 4 1750 0 0 0 0 0 0 0 1 1 1 2 3 2000 0 0 0 0 0 0 0 1 1 l I 3 TV 14 6 11 20 35 49 82 118 185 250 324 514 736 12 5 9 15 27 38 63 91 142 192 248 394 565 l0 3 6 11 20 28 47 67 106 143 185 294 421 8 1 3 6 11 15 26 37 59 79 103 163 234 RHH*, 14 4 8 13 23 32 55 79 123 166 215 341 490 RHW*, RHW-2*, THHW, THW, THW-2 RHH*, 12 3 6 t0 19 26 44 63 99 133 173 274 394 RHW*, RHW-2*, l0 2 5 8 15 20 34 49 77 104 135 214 307 THHW, THW RHH*, 8 1 3 5 9 12 20 29 46 62 81 128 184 RHW*, RHW-2*, THHW, THW, THW-2 70-744 NATIONAL ELECTRICAL CODE 2008 Edition ANNEX C Annex C: Tables Table C.9 Continued CONDUCTORS Conductor Metric Designator(Trade Size) Size (AWC/ 16 21 27 35 41 53 63 78 91 103 129 155 Type kemil) 0/2) (314) (1) (1'/4) (11/2) (2) (2'/2) (3) (31/2) (4) (5) (6) R14H*, 6 1 l 3 7 9 16 22 35 48 62 98 141 RHW*, 4 1 1 3 5 7 12 17 26 35 46 73 105 RHW-2*, 3 l l 2 4 6 l0 14 22 30 39 63 90 TWI 2 l 1 1 3 5 8 12 19 26 33 53 77 THW, 1 0 1 I 2 3 6 8 13 18 23 37 54 THHW, THW-2 110 0 1 1 1 3 5 7 11 15 20 32 46 210 0 1 1 l 2 4 6 10 13 17 27 39 310 0 0 1 l 1 3 5 8 11 14 23 33 410 0 0 1 l 1 3 4 7 9 12 19 27 250 0 0 0 1 1 2 3 5 7 9 15 22 300 0 0 0 1 1 1 3 5 6 8 13 19 350 0 0 0 1 1 1 2 4 6 7 12 17 400 0 0 0 1 1 1 2 4 5 7 l0 15 500 0 0 0 1 1 1 1 3 4 5 9 13 600 0 0 0 0 1 1 1 2 3 4 7 10 700 0 0 0 0 1 1 1 2 3 4 6 9 750 0 0 0 0 0 1 1 1 3 4 6 8 800 0 0 0 0 0 1 1 1 3 3 6 8 900 0 0 0 0 0 1 1 1 2 3 5 7 IOW 0 0 0 0 0 1 1 l 2 3 5 7 1250 0 0 0 0 0 1 l l 1 2 4 5 1500 0 0 0 0 0 0 l l 1 1 3 4 1750 0 0 0 0 0 0 l l 1 1 3 4 2000 0 0 0 0 0 0 0 1 1 1 2 3 THHN, 14 9 17 28 51 70 118 170 265 358 464 736 1055 THWN, 12 6 12 20 37 51 86 124 193 261 338 537 770 THWN-2 10 4 7 13 23 32 54 78 122 164 213 338 485 8 2 4 7 13 18 31 45 70 95 123 195 279 6 1 3 5 9 13 22 32 51 68 89 141 202 4 1 1 3 6 8 14 20 31 42 54 86 124 3 1 1 3 5 7 12 17 26 35 46 73 105 2 1 1 2 4 6 10 14 22 30 39 61 88 1 0 1 1 3 4 7 10 16 22 29 45 65 1/O 0 1 1 2 3 6 9 14 18 24 38 55 2/0 0 1 1 1 3 5 7 11 15 20 32 46 310 0 1 1 l 2 4 6 9 13 17 26 38 410 0 0 1 l 1 3 5 8 10 14 22 31 250 0 0 1 1 1 3 4 6 8 11 18 25 300 0 0 0 l 1 2 3 5 7 9 15 22 350 0 0 0 1 1 l 3 5 6 8 13 19 400 0 0 0 1 1 l 3 4 6 7 12 17 500 0 0 0 1 1 1 2 3 5 6 10 14 600 0 0 0 0 1 1 1 3 4 5 B 12 700 0 0 0 0 1 1 1 2 3 4 7 10 750 0 0 0 0 1 1 1 2 3 4 7 9 800 0 0 0 0 1 1 1 2 3 4 6 9 900 0 0 0 0 0 1 1 1 3 3 6 8 1000 0 0 0 0 0 1 1 1 2 3 5 7 FEP, 14 8 16 27 49 68 115 164 257 347 450 714 1024 FEPE, 12 6 12 20 36 50 84 120 188 253 328 521 747 PFA, 10 4 8 14 26 36 60 86 135 182 235 374 536 PFAH, 8 2 5 8 15 20 34 49 77 104 135 214 307 TFE 6 1 3 6 10 14 24 35 55 74 96 152 218 4 1 2 4 7 10 17 24 38 52 67 106 153 3 l 1 3 6 8 14 20 32 43 56 89 127 2 l 1 3 5 7 12 17 26 35 46 73 105 (Continues) 2008 Edition NATIONAL ELECTRICAL CODE 70-745 Annex C: Tables ANNEX C Table C.9 Continued CONDUCTORS Conductor Metric Designator(Trade Size) Size (AWGI 16 21 27 35 41 53 63 78 91 103 129 155 Type kcmil) ('/2) (-1/4) (1) (11/4) (1Vz) (2) (2Vz) (3) (3'/s) (4) (5) (6) PFA, 1 I l 1 3 5 8 11 18 25 32 51 73 PFAH, TFE PFA, 1/0 0 l 1 3 4 7 10 15 20 27 42 61 PFAH, 2/0 0 l 1 2 3 5 8 12 17 22 35 50 TFE,Z 310 0 1 1 1 2 4 6 10 14 18 29 41 410 0 0 l 1 1 4 5 8 11 15 24 34 Z 14 10 19 33 5y 82 135 198 310 418 542 860 1233 12 7 14 23 42 58 98 141 220 297 385 610 875 10 4 8 14 26 36 60 86 135 182 235 374 536 8 3 5 9 16 22 38 54 85 115 149 236 339 6 2 4 6 11 16 26 38 60 81 104 166 238 4 1 2 4 8 11 i8 26 41 55 72 114 164 3 l 2 3 5 8 13 19 30 40 52 83 119 2 l 1 2 5 6 11 16 25 33 43 69 99 1 0 1 2 4 5 9 13 20 27 35 56 80 XHH, 14 fi Il 20 35 49 82 118 185 250 324 514 736 XHHW, l2 5 9 15 27 38 63 91 142 l92 248 394 565 XHHW-2, l0 3 6 11 20 28 47 67 106 143 185 294 421 Zw 8 1 3 6 11 15 26 37 59 79 103 163 234 6 1 2 4 8 11 19 28 43 59 76 121 173 4 1 1 3 6 8 14 20 31 42 55 87 125 3 1 1 3 5 7 12 17 26 36 47 74 106 2 1 1 2 4 6 10 14 22 30 39 62 89 XHH, l 0 1 1 3 4 7 10 16 27 29 46 66 XHHW, 110 0 1 1 2 3 6 9 14 19 24 39 56 XHHW-2 210 (1 1 1 l 3 5 7 11 16 20 32 46 310 0 1 1 l 2 4 6 9 13 17 27 38 410 0 0 1 1 1 3 5 8 11 14 22 32 250 0 0 1 1 1 3 4 6 9 11 18 26 300 0 0 1 1 1 2 3 5 7 10 15 22 350 0 0 0 1 1 1 3 5 6 8 14 20 400 0 0 0 1 1 1 3 4 6 7 12 17 500 0 0 0 1 1 1 2 3 5 6 10 14 600 0 0 0 0 1 1 1 3 4 5 8 11 700 0 0 0 0 1 1 1 2 3 4 7 10 750 0 0 0 0 l 1 1 2 3 4 6 9 800 {l 0 0 0 l 1 1 1 3 4 6 9 900 0 0 0 0 0 l 1 3 3 .5 8 1000 0 0 0 0 0 l 1 1 2 3 5 7 1250 0 0 0 0 0 l l 1 1 2 4 6 1500 0 0 0 0 0 0 l l 1 1 3 5 1750 0 0 0 0 0 0 l l 1 1 3 4 2000 0 0 0 0 0 0 I l 1 1 2 4 70-746 NATIONAL ELECTRICAL CODE 2008 Edition ANNEX C Annex C: 'fables Table C.9 Continued FIXTURE WIRES Conductor Metric Designator(Trade Size) Size (AWGI 16 21 27 35 41 53 Type kemil) (1/2) (1 14) (1) (1114) (P/s) (2) FFH-2, 18 6 11 19 34 47 79 RFH 2' 16 5 9 16 28 39 67 RFHH-3 SF-2,SFF-2 18 7 14 24 43 59 100 16 6 11 20 35 49 82 14 5 9 16 28 39 67 SF-1,SFF-1 18 13 25 42 76 105 177 RFH-1, 18 10 18 31 56 77 130 RFHH-2,TF TFF,XF, XFF RFHH-2,TF, 16 8 15 25 45 62 105 TFF.XF. XFF XF,XFF 14 6 11 20 35 49 82 TFN,TFFN 18 16 29 50 90 124 209 16 12 22 38 68 95 159 PR PFF, I8 15 28 47 85 118 19S PGF,PGFF, 16 11 22 36 66 91 153 PAR PTF, PTFF,PAFF 14 8 16 27 49 68 115 HF,HFF, 18 19 36 61 110 152 255 ZF,ZFF, 16 14 27 45 81 112 188 ZHF 14 l0 19 33 59 82 138 KF-2, KFF-2 18 28 53 88 09 220 371 16 19 37 62 112 155 261 14 13 25 43 77 107 09 12 9 17 29 53 73 123 10 6 11 20 35 49 82 KF-1, KFF-] 18 33 63 I06 190 263 442 16 23 44 74 133 185 310 14 16 29 50 90 124 209 12 10 19 33 59 82 138 10 7 13 21 39 54 90 XF,XFF 12 3 6 10 19 26 44 l0 2 5 8 15 20 34 Notes: I.This table is for concentric stranded conductors only. For compact stranded conductors,Table C.9(A) should be used. 2. Two-hour fire-rated RHH cable has ceramifiable insulation which has much larger diameters than other RHH wires. Consult manufacturer's conduit fill tables. *Types RHH, RHW, and RHW-2 without outer covering. 2008 Edition NATIONAL ELECTRICAL CODE 70,747 Annex C: Tables ANNEX C Table C.9(A) Maximum Number of Compact Conductors in Rigid PVC Conduit,Schedule 80 (Based on Table 1, Chapter 9) COMPACT CONDUCTORS Conductor Metric Designator(Trade Size) Size (AWG/ 16 21 27 35 41 53 63 78 91 103 129 155 kemil) ('/:) ('/a) (1) (1'/4) (1Vz) (2) (21/2) (3) (33/x) (4) (5) (6) THW, 8 1 3 5 9 13 22 32 50 68 88 140 200 THW-2, 6 1 2 4 7 10 17 25 39 52 68 108 155 THHW 4 1 1 3 5 7 13 18 29 39 51 81 116 2 1 1 1 4 5 9 13 21 29 37 60 85 1 0 1 1 3 4 6 9 15 20 26 42 60 1/0 0 1 1 2 3 6 8 13 17 23 36 52 210 0 1 l l 3 5 7 11 15 19 30 44 310 0 0 l 1 2 4 6 9 12 16 26 37 410 0 0 l 1 1 3 5 8 10 13 22 31 250 0 0 l 1 1 2 4 6 8 11 17 25 300 0 0 0 1 1 2 3 5 7 9 15 21 350 0 0 0 1 1 l 3 5 6 8 13 19 400 0 0 0 1 1 l 3 4 6 7 12 17 500 0 0 0 1 1 l 2 3 5 6 10 14 600 0 0 0 0 l 1 1 3 4 5 8 12 700 0 0 0 0 l 1 1 2 3 4 7 10 750 0 0 0 0 l 1 1 2 3 4 7 10 900 0 0 0 0 0 1 1 2 3 4 6 8 1000 0 0 0 0 0 1 1 1 2 3 5 8 THHN, 8 — — — — — — — — — — — — THWN, 6 3 6 11 15 25 36 57 77 99 158 226 THWN-2 4 1 3 6 9 15 22 35 47 61 98 140 2 1 2 5 6 11 16 25 34 44 70 100 l 1 1 l 3 5 8 12 19 25 33 53 75 110 0 1 l 3 4 7 10 16 22 28 45 64 210 0 1 1 2 3 6 8 13 18 23 37 53 310 0 1 1 1 3 5 7 11 15 19 31 44 4/4 1 0 0 1 1 2 4 6 9 12 16 25 37 250 0 0 1 1 l 3 4 7 10 12 20 29 300 0 0 1 1 1 3 4 6 8 11 17 25 350 0 0 0 1 l 2 3 5 7 9 15 22 400 0 0 0 l 1 1 3 5 6 8 13 19 500 0 0 0 l 1 1 2 4 5 7 11 16 600 0 0 0 l 1 1 l 3 4 6 9 13 700 0 0 0 0 1 1 l 3 4 5 8 12 750 0 0 0 0 1 l I 3 4 5 8 11 900 0 0 0 0 0 l 1 2 3 4 6 8 1000 0 0 0 0 0 l 1 1 3 3 5 8 XHHW, 8 l 4 7 12 17 29 42 65 88 114 181 260 XHHW-2 6 l 3 5 9 13 21 31 48 65 85 134 193 1 1 3 6 9 15 22 35 47 61 98 140 1 1 2 5 6 11 16 25 34 44 70 100 l 1 1 3 5 8 12 19 25 33 53 75 110 0 1 1 3 4 7 10 16 22 28 45 64 2/0 0 1 1 2 3 6 8 13 18 24 38 54 3/0 0 1 1 l 3 5 7 11 15 19 31 44 410 1 0 0 1 l 2 4 6 9 12 16 26 37 250 0 0 1 l 1 3 5 7 10 13 21 30 300 0 0 1 l 1 3 4 6 8 11 17 25 350 0 0 l 1 1 2 3 5 7 10 15 22 400 0 0 0 1 1 1 3 5 7 9 14 20 500 0 0 0 1 1 1 2 4 5 7 11 17 600 0 0 0 1 1 1 1 3 4 6 9 13 700 0 0 0 0 l 1 1 3 4 5 8 12 750 0 0 0 0 l 1 1 2 3 5 7 11 900 0 0 0 0 1 1 l 2 3 4 6 8 1000 1 0 0 0 0 0 I l 1 3 3 6 8 Definition: Compact stranding is the result of a manufacturing process where the standard conductor is compressed to the extent that the interstices(voids between strand wires) are virtually eliminated. 70-748 NATIONAL ELECTRICAL CODE 2008 Edition ANNEX C Annex C: Tables Table C.10 Maximum Number of Conductors or Fixture Wires in Rigid PVC Conduit, Schedule 40 and HDPE Conduit(Based on Table 1, Chapter 9) CONDUCTORS Conductor Metric Designator(Trade Size) Size (AWG/ 16 21 27 35 41 53 63 78 91 103 129 155 Type kcmil) 0/2) 014) (1) (11/4) (1112) (2) (2112) (3) (31/2) (4) (5) (6) RHH, 14 4 7 11 20 27 45 64 99 133 171 269 390 RHH , 12 3 5 9 16 22 37 53 82 110 142 224 323 RHW-2 10 2 4 7 13 18 30 43 66 89 115 181 261 8 1 2 4 7 9 15 22 35 46 60 94 137 6 1 1 1 3 5 7 12 18 28 37 48 76 109 4 I l 2 4 6 10 14 22 29 37 59 85 3 1 l 1 4 5 8 12 19 25 33 52 75 2 1 l 1 3 4 7 10 16 22 28 45 65 1 0 1 l 1 3 5 7 11 14 19 29 43 1/0 0 1 l 1 2 4 6 9 13 16 26 37 2/0 0 0 l 1 l 3 5 8 11 14 22 32 3/0 0 0 l 1 l 3 4 7 9 12 19 28 4/0 0 0 1 1 1 2 4 6 8 10 16 24 250 0 0 0 1 1 1 3 4 6 8 12 18 300 0 0 0 l 1 I 2 4 5 7 11 16 350 0 0 0 1 1 1 2 3 5 6 l0 14 400 0 0 0 1 1 1 l 3 4 6 9 13 500 0 0 0 0 1 1 1 3 4 5 8 11 600 0 0 0 0 1 l 1 2 3 4 6 9 700 0 0 0 0 0 1 1 l 3 3 6 8 750 0 0 0 0 0 1 1 1 2 3 5 8 800 0 0 0 0 0 1 1 1 2 3 5 7 900 0 0 0 0 0 1 1 1 2 3 5 7 1000 0 0 0 0 0 1 1 1 1 3 4 6 1250 0 0 0 0 0 0 1 1 1 1 3 5 1500 0 0 0 0 0 0 1 1 1 1 3 4 1750 0 0 0 0 0 0 1 1 1 I 2 3 2000 0 0 0 0 0 0 0 I 1 1 2 3 TW 14 8 14 24 42 57 94 135 209 280 361 568 822 12 6 11 18 32 44 72 103 160 215 277 436 631 10 4 8 13 24 32 54 77 119 160 206 325 470 8 2 4 7 13 18 30 43 66 89 115 181 261 R14H*, 14 5 9 16 28 38 63 90 139 186 240 378 546 RHW*, RHW-2*, THHW, THW, THW-2 RHH*, 12 4 8 12 22 30 50 72 112 150 193 304 439 RHW*, RHW-2*, 10 3 6 10 17 24 39 56 87 117 150 237 343 THHW, THW RHH*, 8 1 3 6 f0 14 23 33 52 70 90 142 205 RHW*, RHW-2*, THHW, THW, THW-2 (Continues) 2008 Edition NATIONAL ELECTRICAL CODE 70-749 Annex C: Tables ANNEX C Table C.10 Continued CONDUCTORS Conductor Metric Designator(Trade Size) �`T Size (ANVGI 16 21 27 35 41 53 63 78 91 103 129 155 Type kemil) (I/z) (1/4) (1) {1114) f11/2) (2) (21/2) (3) (3°/a) (4) (5) (6) RHH*, 6 1 2 4 8 11 l8 26 40 53 69 109 157 RHW*, 4 1 1 3 6 8 13 19 30 40 51 81 117 RHW-2* 3 1 1 3 5 7 11 16 25 34 44 69 100 TW 2 1 1 2 4 6 10 14 22 29 37 59 85 THW, I 0 1 l 3 4 7 10 15 20 26 41 60 THHW. 110 U 1 l 2 3 6 8 13 17 22 35 51 THW-2 210 U 1 l 1 3 5 7 ll IS 19 30 43 310 0 1 l 1 2 4 6 9 12 16 2.5 36 410 0 0 1 1 l 3 5 8 10 13 21 30 250 0 U 1 1 l 3 4 6 8 11 17 25 300 0 0 1 1 l 2 3 5 7 9 15 21 350 0 0 0 l 1 1 3 5 6 8 13 19 400 U U 0 l 1 1 3 4 6 7 12 17 500 0 0 0 l 1 1 2 3 5 6 10 14 600 0 0 0 0 1 1 1 3 4 5 8 11 700 0 0 0 U 1 1 l 2 3 4 7 10 750 0 U 0 U 1 1 l 2 3 4 6 10 800 U U U 0 1 1 l 2 3 4 6 9 9(x} 0 0 0 0 0 1 1 l 3 3 6 8 IM) 0 0 0 0 (1 1 1 l 2 3 5 7 1250 0 0 0 0 0 l 1 l 1 2 4 6 1500 0 0 (} 0 0 l 1 l l 1 3 5 1750 {l 0 0 U U 0 1 1 l 1 3 4 2000 0 0 0 (l 0 0 1 1 l 1 3 4 TH HN, 14 11 21 34 60 82 135 193 299 401 517 815 1178 THWN, 12 8 15 25 43 59 99 141 218 293 377 594 859 THWN-2 10 5 9 15 27 37 62 89 137 184 238 374 541 8 3 5 9 16 21 36 51 79 106 137 216 312 6 1 4 6 11 15 26 37 57 77 99 156 225 4 1 2 4 7 9 16 22 35 47 61 96 138 3 1 1 3 6 8 13 19 30 40 51 81 117 2 1 1 3 5 7 11 16 25 33 43 68 98 l 1 1 1 3 5 8 12 18 25 32 50 73 110 1 1 1 3 4 7 10 15 21 27 42 61 210 fl 1 1 2 3 6 8 13 17 22 35 51 310 0 l 1 1 3 5 7 11 14 18 29 42 410 0 l 1 1 2 4 6 9 12 15 24 35 250 0 0 1 1 l 3 4 7 10 12 20 28 300 U 0 l 1 l 3 4 6 8 11 17 24 350 0 0 l 1 1 2 3 5 7 9 15 21 400 0 0 0 1 1 1 3 5 6 8 13 19 500 0 0 U 1 1 1 2 4 5 7 11 16 600 0 0 0 l 1 1 l 3 4 5 9 13 700 0 0 0 0 1 1 1 3 4 5 8 11 750 U U 0 0 1 1 1 2 3 4 7 Il 8(x} U 0 0 0 1 1 1 2 3 4 7 10 900 0 0 0 0 1 l 1 2 3 4 6 9 1000 {} 0 0 0 U l 1 1 3 3 6 8 FER 14 11 20 33 58 79 131 188 290 389 502 790 1142 FEPB, 12 8 15 24 42 58 96 137 212 284 366 577 834 PFA, 10 6 IU 17 30 41 69 98 152 204 263 414 598 PFA H. 8 3 6 10 17 24 39 56 87 117 150 237 343 TFE 6 2 4 7 12 17 28 40 62 83 107 169 244 4 1 3 5 8 12 19 28 43 58 75 lib 170 3 1 2 4 7 10 16 23 36 48 62 98 142 2 1 l 3 6 8 13 19 30 40 51 81 117 70-750 NATIONAL ELECTRICAL CODE 2008 Edition ANNEX C Annex C: Tables Table C.10 Continued CONDUCTORS Conductor Metric Designator(Trade Size) Size (ANVG/ 16 21 27 35 41 53 63 78 91 103 129 155 Tt.Pe kcmil) (1/2) (3/4) (1) 1114 1 1112.) (2) (21/2) (3) (3 IA) (4) (5) (6) PFA, I 1 l 2 4 5 9 13 20 28 36 56 81 PFAH, TFE PFA, 110 1 l 1 3 4 8 11 17 23 30 47 68 PFAH, 2/0 0 1 1 3 4 6 9 14 19 24 39 56 TFE,Z 3/0 0 1 1 2 3 5 7 12 16 20 32 46 4/0 0 1 1 1 2 4 6 9 13 16 26 38 Z 14 13 24 40 70 95 158 776 350 469 605 952 1376 12 9 17 28 49 68 112 160 248 333 429 675 976 10 6 l0 17 30 41 69 98 152 204 263 414 598 8 3 6 11 19 26 43 62 96 129 166 261 378 6 2 4 7 13 18 30 43 67 90 116 184 265 4 l 3 5 9 12 21 30 46 62 80 126 183 3 l 2 4 6 9 15 22 34 45 58 92 133 2 l 1 3 5 7 12 18 28 38 49 77 111 1 1 1 2 4 6 10 14 23 30 39 62 90 XHH, 14 8 14 24 42 57 94 135 209 280 361 568 822 XHHW, 12 6 11 18 32 44 72 103 160 215 277 436 631 XHHW-2 10 4 8 13 24 32 54 77 119 160 206 325 470 ZW 8 2 4 7 13 18 30 43 66 89 115 181 261 6 1 3 5 10 13 22 32 49 66 85 134 193 4 1 2 4 7 9 16 23 35 48 61 97 140 3 1 1 3 6 8 13 19 30 40 52 82 118 2 1 1 3 5 7 11 16 25 34 44 69 99 XHH, I 1 1 l 3 5 8 12 19 25 32 51 74 XHHW, 1/0 1 1 l 3 4 7 10 16 21 27 43 62 XHHW-2 2/0 0 1 l 2 3 6 8 13 17 23 36 52 310 0 l l 1 3 5 7 11 14 19 30 43 4/0 0 l l 1 2 4 6 9 12 15 24 35 250 0 0 1 1 1 3 5 7 10 13 20 29 300 0 0 l 1 l 3 4 6 8 11 17 25 350 0 0 1 1 1 2 3 5 7 9 15 22 400 0 0 0 1 1 1 3 5 6 8 13 19 500 0 0 0 1 1 1 2 4 5 7 11 16 600 0 0 0 1 1 1 1 3 4 5 9 13 700 0 0 0 0 1 1 1 3 4 5 8 11 750 0 0 0 0 1 1 l 2 3 4 7 11 800 0 0 0 0 1 1 l 2 3 4 7 10 900 0 0 0 0 1 1 l 2 3 4 6 9 1000 0 0 0 0 0 1 l 1 3 3 6 8 1250 0 0 0 0 0 1 1 1 1 3 4 6 1500 0 0 0 0 0 1 1 1 1 2 4 5 1750 0 0 0 0 0 0 l 1 1 1 3 5 2000 0 0 0 0 0 0 l 1 1 1 3 4 (Continues) 2008 Edition NATIONAL ELECTRICAL CODE 70-751 Annex C: Tables ANNEX C Table C.10 Continued FIXTURE WIRES Conductor Metric Designator(Trade Size) Size (ANVG/ 16 21 27 35 41 53 Type kcmil) (1/2) (1/4) (1) (1V4} (P/2) (:? FFH-2, 18 8 14 23 40 54 90 RFH-2, 16 6 12 19 33 46 76 RFHH-3 SF-2,SFF-2 18 10 17 29 50 69 114 16 8 14 24 42 57 94 14 6 12 19 33 46 76 SF-1,SFF-1 18 17 31 51 89 122 RFHH-2.TR 18 13 23 38 66 90 149 TFR XF, XFF RFH-1, RFHH-2,TF. 16 10 18 30 53 73 120 TFF, XF, XFF XF,XFF 14 8 14 24 42 57 94 TFN.TFFN 18 20 37 60 105 144 239 16 16 28 46 80 ll0 183 PF, PFF, 18 19 35 57 100 137 227 PGF, PGFF, 16 15 27 44 77 106 175 PAF, PTF, PTFF PAFF 14 11 20 33 58 79 131 HE HFF, 18 25 45 74 129 176 292 ZF,ZFF, 16 18 33 54 95 130 216 ZHF 14 13 24 40 70 95 158 KF-2, KFF-2 18 36 65 107 187 256 424 16 26 46 75 132 180 299 14 17 31 52 90 124 205 12 12 22 35 62 85 141 10 8 14 24 42 57 94 KF-1, KFF-1 18 43 78 128 223 305 506 16 30 55 90 157 214 355 14 20 37 60 105 144 239 12 13 24 40 70 95 158 10 9 16 26 45 62 103 XF,XFF 12 4 8 12 22 30 50 10 3 6 10 17 24 39 Notes: I.This table is for concentric stranded conductors only. For compact stranded conductors,Table C.10(A) should be used. 2.Two-hour fire-rated RHH cable has ceramifiable insulation which has much larger diameters than other RHH wires. Consult manufacturer's conduit fill tables. *Types RHH, RHW,and RHW-2 without outer covering. 70-752 NATIONAL_ELECTRICAL CODF. 2008 Edition ANNEX C Annex C: Tables Table C.10(A) Maximum Number of Compact Conductors in Rigid PVC Conduit, Schedule 40 and HDPE Conduit (Based on Table 1, Chapter 9) COMPACT CONDUCTORS Conductor Metric Designator(Trade Size) Size — (A69G/ 16 21 27 35 41 53 63 78 91 103 129 155 Tv Pe kcmil) (1/2) (•114) (1) (1114) (11/2) (2) (2'/z) (3) (31/2) (4) (5) (6) THW. 8 1 4 6 11 15 26 37 57 76 98 155 224 THW-2. 6 1 3 5 9 12 20 28 44 59 76 119 173 THHW 4 1 1 3 6 9 15 21 33 44 57 89 129 2 1 1 2 5 6 11 15 24 32 42 66 95 1 1 1 1 3 4 7 11 17 23 29 46 67 110 0 1 1 3 4 6 9 15 20 25 40 58 210 0 1 1 2 3 5 8 12 16 21 34 49 310 0 1 1 1 3 5 7 10 14 18 29 42 410 0 1 1 1 2 4 5 9 12 15 24 35 250 0 0 1 1 1 3 4 7 9 12 19 27 300 0 0 1 1 1 2 4 6 8 10 16 24 350 0 0 1 1 1 2 3 5 7 9 15 21 400 0 0 0 1 1 1 3 5 6 8 13 19 500 0 0 0 1 1 1 2 4 5 7 11 16 600 0 U 0 1 1 1 l 3 4 5 9 13 700 0 0 0 0 1 1 l 3 4 5 8 12 750 0 0 U 0 1 1 l 2 3 5 7 11 900 U t) 0 0 1 1 l 2 3 4 6 9 1000 0 0 0 U 1 1 l 1 3 4 6 9 THHN, 8 — — — — — — — — — — — — THWN, 6 2 4 7 13 17 29 41 64 86 Ili 175 253 THWN-2 4 I 2 4 8 11 18 25 40 53 68 108 156 2 1 l 3 5 8 13 18 28 38 49 77 112 1 1 l 2 4 6 9 14 21 29 37 58 84 110 1 l 1 3 5 8 12 18 24 31 49 72 210 0 l l 3 4 7 9 15 20 26 41 59 310 0 l l 2 3 5 8 12 17 22 34 50 410 1 0 1 l 1 3 4 6 10 14 18 28 41 250 0 0 l 1 1 3 5 8 11 14 22 32 300 0 0 l 1 1 3 4 7 9 12 19 28 350 0 U l 1 1 3 4 6 8 10 17 24 400 0 0 l 1 1 2 3 5 7 9 15 22 500 0 0 0 1 1 1 3 4 6 8 13 18 600 0 (1 0 1 1 l 2 4 5 6 10 15 700 0 U 0 1 1 l l 3 4 5 9 13 750 0 0 0 1 1 l l 3 4 5 8 12 900 0 U 0 0 1 l 1 2 3 4 6 9 1000 0 U U 0 1 l l 2 3 4 6 9 XHHW, 8 3 5 8 14 20 33 47 73 99 127 200 290 XHHW-2 6 l 4 6 11 15 25 35 55 73 94 149 215 4 1 2 4 8 11 18 25 40 53 68 108 156 2 1 1 3 5 8 13 18 28 38 49 77 112 1 1 1 2 4 6 9 14 21 29 37 58 84 110 1 1 1 3 5 8 12 is 24 31 49 72 210 1 1 1 3 4 7 10 15 20 26 42 60 310 0 1 1 2 3 5 8 12 17 22 34 50 410 1 0 1 1 1 3 5 7 W 14 18 29 42 250 0 0 1 1 1 4 5 8 11 14 23 33 300 0 0 1 1 1 3 4 7 9 12 19 28 350 U 0 1 1 1 3 4 6 8 11 17 25 400 0 0 1 1 1 2 3 5 7 10 15 22 500 0 0 0 1 1 l 3 4 h 8 13 18 600 0 0 0 1 1 l 2 4 5 6 10 15 700 0 0 U 1 1 l 1 3 4 5 9 13 750 0 0 0 1 1 l 1 3 4 5 8 12 900 0 0 U 0 1 l 1 2 3 4 6 9 1000 1 0 0 0 0 1 l 1 2 3 4 6 9 Definition: Compact stranding is (he result of a manufacturing process where the standard conductor is compressed to the extent that the interstices(voids between strand wires) are virtually eliminated, 2008 Edition NATIONAL ELECTRICAL CODE 70-753 Annex C: Tables ANNEX C Table C.11 Maximum Number of Conductors or Fixture Wires in Type A, Rigid PVC Conduit (Based on Table 1, Chapter 9) CONDUCTORS Conductor Metric Designator(Trade Size) Size (AWG/ 16 21 27 35 41 53 63 78 91 103 Type kcmil) ('/2) (-'14) (1) (1'/a) (1'/s) (2) (21/2) (3) (3'/2) (4) RHH, 14 5 9 15 24 31 49 74 112 146 I87 RHW, 12 4 7 12 20 26 41 61 93 121 155 RHW-2 10 3 6 10 16 21 33 50 75 98 125 8 l 3 5 8 11 17 26 39 51 65 6 l 2 4 6 9 14 21 31 41 52 4 1 1 3 5 7 11 16 24 32 41 3 l 1 3 4 6 9 14 21 28 36 2 l 1 2 4 5 8 12 18 24 31 1 0 1 1 2 3 5 8 12 16 20 1/0 (] 1 1 2 3 5 7 10 14 18 2/0 0 1 1 1 2 4 6 9 12 15 310 0 1 1 1 l 3 5 8 10 13 410 0 0 1 l 1 3 4 7 9 11 250 0 0 1 l 1 l 3 5 7 8 300 0 0 1 l 1 l 3 4 6 7 350 0 0 0 1 1 1 2 4 5 7 400 {} 0 0 1 1 1 2 4 5 6 500 0 0 0 1 1 1 1 3 4 5 600 0 0 0 0 1 1 1 2 3 4 700 0 0 0 0 1 1 1 2 3 4 750 0 0 0 0 1 1 1 1 3 4 800 0 0 0 0 1 1 1 1 3 3 900 0 0 0 0 0 1 1 l 2 3 1000 0 0 0 0 0 1 l l 2 3 1250 0 0 0 0 0 1 l 1 1 2 1500 0 0 0 0 0 0 1 1 1 1 1750 0 0 0 0 0 0 1 1 1 1 2000 0 0 0 0 0 0 1 1 1 1 TW 14 11 18 31 51 67 105 157 235 307 395 12 8 14 24 39 51 80 120 181 236 303 10 6 10 18 29 38 60 89 135 176 226 8 3 6 10 16 21 33 50 75 98 125 RHH*, 14 7 12 20 34 44 70 104 157 204 262 RHW*, RHW-2*, THHW, THW, THW-2 RHH*, 12 6 10 16 27 35 56 84 126 164 211 RHW*, RHW-2*, 10 4 8 13 21 28 44 65 98 128 165 THHW, THW RHH*, 8 2 4 8 12 M 26 39 59 77 98 RHW*, RHW-2*, THHW, THW, THW-2 RHH*, 6 l 3 6 9 13 20 30 45 59 75 RHW*, RHW-2*, TW, THHW, THW, THW-2 70-754 NATIONAL ELECTRICAL CODE 2008 Edition ANNEX C Annex C: Tables Table C.11 Continued CONDUCTORS Conductor Metric Designator(Trade Size) Size (AWG/ 16 21 27 35 41 53 63 78 91 103 Tvpe kcmil) Wz) (-'14) (1) (P/4) (1'/:) (2) (2J/2) (3) (31/2) (4) RHH*, 4 1 2 4 7 9 15 22 33 44 56 RHW*, 3 1 1 4 6 8 13 19 29 37 48 RHW-2*, 2 1 1 3 5 7 11 16 24 32 41 TWA l 1 1 1 3 5 7 11 17 22 29 THW, 1/0 1 1 1 3 4 6 10 14 19 24 THHW, 210 0 1 1 2 3 5 8 12 16 21 THW-2 3/0 0 1 1 1 3 4 7 10 13 17 4/0 0 1 1 1 2 4 6 9 11 14 250 0 0 1 1 1 3 4 7 9 12 300 0 0 1 1 1 2 4 6 8 10 350 0 0 1 1 l 2 3 5 7 9 400 0 0 1 1 1 1 3 5 6 8 500 0 0 0 1 1 1 2 4 5 7 600 0 0 0 1 l 1 1 3 4 T- 700 0 0 0 1 l 1 1 3 4 5 750 0 0 0 1 l 1 1 3 3 4 S00 0 0 0 0 l 1 1 2 3 4 900 0 0 0 0 l 1 1 2 3 4 1000 0 0 0 0 l 1 1 1 3 3 1250 0 0 0 0 0 1 1 1 1 3 1500 0 0 0 0 0 1 1 1 1 2 1750 0 0 0 0 0 0 1 1 1 l 2000 0 0 0 0 0 0 1 1 1 l THHN, 14 16 27 44 73 96 150 225 338 441 566 THWN, 12 11 19 32 53 70 109 164 246 321 412 THWN-2 10 7 12 20 33 44 69 103 155 202 260 8 4 7 12 19 25 40 59 89 l)7 150 6 3 5 8 14 18 28 43 64 84 108 4 3 5 8 11 17 26 39 52 66 3 2 4 7 9 15 22 33 44 56 2 1 3 6 8 12 19 28 37 47 l 1 2 4 6 9 14 21 27 35 110 1 1 2 4 5 8 11 17 23 29 210 1 1 1 3 4 6 10 14 19 24 310 0 1 1 2 3 5 8 12 16 20 4/0 0 1 1 1 3 4 6 10 13 17 250 0 1 1 1 2 3 5 8 10 14 300 0 0 1 . 1 l 3 4 7 9 12 350 0 0 1 1 1 2 4 6 8 10 400 0 0 1 1 1 2 3 5 7 9 500 0 0 1 1 l 1 3 4 6 7 600 0 0 0 1 1 1 2 3 5 6 700 0 0 0 1 1 1 1 3 4 5 750 0 0 0 1 1 1 1 3 4 5 800 0 0 0 1 1 1 1 3 4 5 900 0 0 0 0 l 1 1 2 3 4 1000 0 0 0 0 1 1 1 2 3 4 FEP, 14 15 26 43 70 93 146 218 327 427 549 FEPB, 12 li 19 31 51 68 106 159 239 312 400 PFA, 10 8 13 22 37 48 76 114 171 224 287 PFAH, 8 4 8 13 21 28 44 65 98 128 165 TFE 6 3 5 9 15 20 31 46 70 91 117 4 4 6 10 14 21 32 49 64 82 3 3 5 8 11 18 27 40 53 68 2 2 4 7 9 15 22 33 44 56 (Continues) 2008 Edition NATIONAL ELECTRICAL CODE 70-755 Annex C: Tables ANNEX C Table C.11 Continued CONDUCTORS Conductor Metric Designator(Trade Size) Size (AWG/ 16 21 27 35 41 53 63 78 91 103 Type kcmil) ('/2) (3/4) (1) (11/4) (11/1) (2) (21/2) (3) (3'/2) (4) PFA, 1 1 1 3 5 6 10 15 23 30 39 PFAH, TFE PFA, 110 1 2 4 5 8 13 19 25 32 PFAH, 2/0 1 l 3 4 7 10 16 21 27 TFE,Z 3/0 1 l 3 3 6 9 13 17 22 410 0 1 l 2 3 5 7 11 14 18 Z 14 18 31 52 85 112 175 263 395 515 661 12 13 22 37 60 79 124 186 280 365 469 10 8 13 22 37 48 76 114 171 224 287 8 5 8 14 23 30 48 72 108 141 181 6 3 6 10 16 21 34 50 76 99 127 4 2 4 7 II 15 23 35 52 68 88 3 1 3 5 8 11 17 25 38 50 64 2 1 2 4 7 9 14 21 32 41 53 1 1 1 3 5 7 11 17 26 33 43 XHH, 14 11 18 31 51 67 105 157 235 307 395 XHHW, 12 8 14 24 39 51 80 120 181 236 303 XHHW-2, 10 6 10 18 29 38 60 89 135 176 226 ZW 8 3 6 1() 16 21 33 50 75 98 125 6 2 4 7 12 15 24 37 55 72 93 4 1 3 5 8 11 18 26 40 52 67 3 1 2 4 7 9 15 22 34 44 57 2 1 l 3 6 8 12 19 28 37 48 XHH, I 1 1 3 4 6 9 14 21 28 35 XHHW, 110 1 l 2 4 5 8 12 18 23 30 XHHW-2 210 1 l 1 3 4 6 10 15 19 25 310 0 l 1 2 3 5 8 12 16 20 410 0 1 1 1 3 4 7 10 13 17 250 0 l 1 1 2 3 5 8 11 14 300 0 0 1 1 1 3 5 7 9 12 350 U 0 1 l 1 3 4 6 8 10 400 (1 0 1 1 1 2 3 5 7 9 500 0 0 1 1 1 1 3 4 6 8 600 0 n n l 1 1 2 3 5 6 700 0 0 0 l 1 1 1 3 4 5 750 0 0 0 I I l 1 3 4 5 80 n (} () 1 1 1 1 3 4 5 900 0 n 0 n 1 1 1 2 3 4 1()00 0 0 n 0 1 1 1 2 3 4 1250 0 0 0 0 0 1 1 1 2 3 150() 0 0 0 0 0 1 1 1 1 2 1750 0 0 0 {} 0 1 1 1 1 2 2000 0 0 0 0 0 {} 1 1 1 1 70-756 NATIONAL ELECTRICAL CODE 2008 Edition ANNEX C Annex C: Tables Table C.11 Continued FIXTURE WIRES Conductor Metric Designator(Trade Size) Size (ANVG/ 16 21 27 35 41 53 Type kemil) (�/a) (314) (1) (11/.) (V/2) (2) FFH-2, 18 10 18 30 48 64 100 RFH-2, 16 9 15 25 41 54 85 RFHH-3 SF-2,SFF-2 18 13 22 37 61 8I 127 16 11 18 31 51 67 105 14 9 15 25 41 54 85 SF-1,SFF-1 i8 23 40 66 108 143 224 RFH-1, 18 17 29 49 80 105 165 RFHH-2,TF, TFI;XF, XFF RFHH-2,TF, 16 14 24 39 65 85 134 TFF,XF, XFF XF,XFF 14 11 18 31 51 67 105 TFN,TFFN 18 28 47 79 128 169 265 16 21 36 60 98 129 202 PF, PFF, 18 26 45 74 122 160 251 PGR PGFF, 16 20 34 58 94 124 194 PAF,PTF, PTFF.PAFF 14 15 26 43 70 93 146 HF, HFF,ZF, 18 34 58 96 157 206 324 ZFF,ZHF 16 25 42 71 116 152 239 14 18 31 52 85 112 175 KF-2, KFF-2 18 49 84 140 228 300 470 16 35 59 98 160 211 331 14 24 40 67 110 145 228 12 16 28 46 76 100 157 10 11 18 31 51 67 105 KF-1, KFF-1 18 59 100 167 272 357 561 16 41 70 117 191 251 394 14 28 47 79 128 169 265 12 18 31 52 85 112 175 10 12 20 34 55 73 115 XF,XFF 12 6 10 16 27 35 56 10 4 8 13 21 28 44 Notes: 1.This table is For concentric stranded conductors only. For compact stranded conductors,Table C.I I(A) should be used. 2.Two-hour fire-rated RHH cable has ceramitiable insulation which has much larger diameters than other RHH wires. Consult manufacturer's conduit fill tables. *Types RHH, RHW,and RWH-2 without outer covering. 2008 Edition NATIONAL ELECTRICAL CODE 70-757 Annex C: Tables ANNEX C Table C.11(A) Maximum Number of Compact Conductors in Type A, Rigid PVC Conduit (Based on Table I, Chapter 9) COMPACT CONDUCTORS Conductor Metric Designator(Trade Size) Size (AWG/ 16 2I 27 35 41 53 63 78 91 103 Type kemil) (�/2) (;/4! (1) (11/4) (Ph) (2) (2'/2) (3) (31/x) (4) THW, 8 3 5 8 14 18 28 42 64 84 l07 THW-2, 6 2 4 6 10 14 22 33 49 65 83 THHW 4 1 3 5 8 10 16 24 37 48 62 2 1 1 3 6 7 12 18 27 36 46 1 1 1 2 4 5 8 13 19 25 32 110 1 1 l 3 4 7 11 16 21 28 2/0 1 1 l 3 4 6 9 14 18 23 310 0 1 l 2 3 5 8 12 15 20 4/0 0 1 l 1 3 4 6 10 13 17 250 0 1 l 1 1 3 5 8 10 13 300 0 0 l 1 l 3 4 7 9 11 350 0 0 l 1 l 2 4 6 8 10 400 0 0 l 1 l 2 3 5 7 9 500 0 0 1 1 l 1 3 4 6 8 600 0 0 0 1 l l 2 3 5 6 700 0 0 U 1 1 1 1 3 4 5 750 0 0 0 1 1 l 1 3 4 5 900 0 0 0 0 1 l 2 2 3 4 1000 0 0 0 0 1 1 1 2 3 4 THHN, 8 — — — — — — -- — THWN, 6 3 5 9 15 20 32 48 72 94 121 THWN-2 4 1 3 6 9 12 20 30 45 58 75 2 1 2 4 7 9 14 21 32 42 54 1 1 1 3 5 7 10 16 24 31 40 1/0 1 1 2 4 6 9 13 20 27 34 2/0 1 1 1 3 5 7 11 17 22 28 3/0 1 1 1 3 4 6 9 14 18 24 4/0 1 0 1 1 2 3 5 8 11 15 19 250 0 1 1 l 2 4 6 9 12 15 30O 0 1 1 l 1 3 5 8 10 13 350 0 0 1 l 1 3 4 7 9 11 400 0 0 1 I 1 2 4 6 8 l0 500 O U 1 1 1 2 3 5 7 9 600 0 0 0 1 1 1 1 4 5 7 700 0 0 0 1 1 1 2 3 5 6 750 0 0 0 1 1 1 2 3 4 6 900 0 0 0 1 1 1 2 3 4 5 1000 0 0 0 0 1 1 1 2 3 4 XHHW, 8 4 6 11 18 23 37 55 83 108 139 XHHW-2 6 3 5 8 13 17 27 41 62 80 103 4 1 3 6 9 12 20 30 45 58 75 2 1 2 4 7 9 14 21 32 42 54 1 1 1 3 5 7 10 16 24 31 40 110 1 1 2 4 6 9 13 20 27 34 210 1 1 l 3 5 7 11 17 22 29 310 1 1 l 3 4 6 9 14 18 24 4/0 0 1 l 2 3 5 8 12 15 20 250 0 1 1 1 2 4 6 9 12 16 300 0 l l 1 1 3 5 8 10 13 350 0 U l 1 1 3 5 7 9 12 400 0 0 1 1 1 3 4 6 8 11 500 0 U 1 l 1 2 3 5 7 9 600 0 0 0 l 1 1 3 4 5 7 700 0 0 U l 1 1 2 3 5 6 750 0 0 0 l 1 1 2 3 4 6 900 0 0 0 l 1 1 2 3 4 5 1000 0 U 0 U 1 1 1 2 3 4 Definition: Compacr stranding is the result of a manufacturing process where the standard conductor is compressed to the extent that the interstices (voids between strand wires) are virtually eliminated. 70-758 NATIONAL.ELECTRICAL,CODE 2008 Edition ANNEX C Annex C: Tables Table C.12 Maximum Number of Conductors in Type EB, PVC Conduit (Bused on Table 1, Chapter 9) CONDUCTORS Conductor Metric Designator(Trade Size) Size (AWG/ 53 78 91 103 129 155 Type kcmil) (2) (3) (3'/1 (4) (5) (6) RHH,RHW, 14 53 119 155 197 303 430 RHW-2 12 44 98 128 163 251 357 10 35 79 104 132 203 288 8 18 41 54 69 106 151 6 15 33 43 55 85 121 4 Il 26 34 43 66 94 3 10 23 30 38 58 83 2 9 20 26 33 50 72 1 6 13 17 21 33 47 1/0 5 ll IS 19 29 41 2/0 4 10 13 16 25 36 3/0 4 8 11 14 22 31 4/0 3 7 9 12 18 26 250 2 5 7 9 14 20 300 l 5 6 8 12 17 350 l 4 5 7 11 16 400 l 4 5 6 10 14 50() l 3 4 5 9 12 600 l 3 3 4 7 10 700 l 2 3 4 6 9 750 l 2 3 4 6 9 800 l 2 3 4 6 8 900 l 2 3 5 7 1000 l 1 2 3 5 7 1250 l 1 l 2 3 5 1500 0 1 1 1 3 4 1750 0 1 1 1 3 4 2000 0 1 1 1 2 3 TW 14 111 25() 327 415 638 907 12 85 192 251 319 490 696 10 63 143 187 238 365 519 8 35 79 104 132 203 288 RHH*, 14 74 166 217 276 424 603 RHW*, RHW-2*, THHW, THW, TH W-2 RHH*, 12 59 134 175 222 341 485 RHW*, RHW-2*, 10 46 104 136 173 266 378 THHW. TH W RHH*, 8 28 62 81 104 159 227 RHW*, RHW-2*, THHW, TH W, THW-2 (Cautinues) 2008 Edition NATIONAL ELECTRICAL CODE 70-759 Annex C: Tables ANNEX C Table C.12 Continued CONDUCTORS Conductor Metric Designator(Trade Size) Size (AWGI 53 78 91 103 I29 155 Type kemil) (2) (3) (31/2) (4) (5) (6) RHH*, 6 21 48 62 79 122 173 RHW*, 4 16 36 46 59 91 129 RHW-2*, 3 13 30 40 51 78 Ill TW,THW, 2 11 26 34 43 66 94 THHW, l 8 18 24 30 46 66 THW-2 110 7 15 20 26 40 56 210 6 13 17 22 34 48 310 5 11 1.3 18 28 40 410 4 9 12 15 24 34 250 3 7 l0 12 19 27 300 3 6 8 11 17 24 350 2 6 7 9 15 21 400 2 5 7 8 13 19 500 1 4 5 7 11 16 600 1 3 4 6 9 13 700 1 3 4 5 8 11 750 1 3 4 5 7 II 800 l 3 3 4 7 10 900 1 2 3 4 6 9 I(m 1 2 3 4 6 8 1250 1 1 2 3 4 6 1500 1 1 1 2 4 6 1750 1 1 l 2 3 5 2000 0 l l l 3 4 THHN. 14 159 359 468 Sys 915 1300 THWN, 116 262 342 434 667 948 THWN-2 0 73 165 215 274 420 597 8 42 95 124 158 242 344 6 30 68 89 114 175 248 4 19 42 55 70 107 153 3 16 36 46 59 91 129 2 13 30 39 50 76 109 l 10 22 29 37 57 80 1/0 8 18 24 31 48 68 210 7 15 20 26 40 56 3/0 5 13 17 21 33 47 410 4 10 14 l8 27 39 250 4 8 11 14 22 31 300 3 7 10 12 19 27 350 3 6 8 11 17 24 400 2 6 7 l0 15 21 500 1 5 6 8 12 18 600 1 4 5 6 10 14 700 1 3 4 6 9 12 750 1 3 4 5 8 12 800 1 3 4 5 8 11 900 1 3 3 4 7 10 1000 1 2 3 4 6 9 FEP,FEPB, 14 155 348 454 578 888 1261 PFA. PFAH, 12 113 254 332 422 648 920 TFE 10 81 182 238 302 465 660 8 46 104 136 173 266 378 6 33 74 97 123 189 269 4 23 52 68 86 132 188 3 19 43 56 72 110 157 2 16 36 46 59 91 129 70-760 NATIONAL ELECTRICAL CODE 2008 Edition ANNEX C Annex C:Tables Table C.12 Continued CONDUCTORS Conductor Metric Designator(Trade Size) Size (AWG/ 53 78 91 103 129 155 Type kcmil) (2) (3) (31/2) (4) (5) (6) PFA, PFA H, l 11 25 32 41 63 90 TFE PFA, PFAH. 110 9 20 27 34 53 75 TFE,Z 210 7 17 22 28 43 62 3/0 6 14 18 23 36 51 410 5 11 15 19 29 42 Z 14 186 419 547 696 1069 1519 12 132 297 388 494 759 1078 10 81 182 238 302 465 660 8 51 115 150 191 294 417 6 36 81 105 134 206 293 4 24 55 72 92 142 201 3 18 40 53 67 104 147 2 15 34 44 56 86 122 l 12 27 36 45 70 99 XHH, 14 111 250 327 415 638 907 XHHW, 12 85 192 251 319 490 696 XHHW-2, 10 63 143 187 238 365 519 ZW 8 35 79 104 132 203 288 6 26 59 77 98 150 213 4 19 42 56 71 109 155 3 i6 36 47 60 92 131 2 13 30 39 50 77 110 XHH, 1 10 22 29 37 58 82 XHHW. 110 8 19 25 31 48 69 XHHW-2 2/0 7 16 20 26 40 57 3/0 6 13 17 22 33 47 4/0 5 11 14 18 27 39 250 4 9 11 15 22 32 300 3 7 10 12 9 28 350 3 6 9 11 24 400 2 6 8 10 22 500 l 5 6 8 18 600 l 4 5 6 10 14 700 l 3 4 6 9 12 750 l 3 4 5 8 12 800 1 3 4 5 8 11 900 1 3 3 4 7 10 1000 1 2 3 4 6 9 1250 1 l 2 3 5 7 1500 1 1 l 3 4 6 1750 1 l l 2 4 5 2000 0 1 1 l 3 5 Notes: 1.This table is for concentric stranded conductors only. For compact stranded conductors,Table C.12(A) should be used. 2.Two-hour fire-rated RHH cable has ceramifiable insulation which has much larger diameters than other RHH wires. Consult manufacturer's conduit fill tables. Types RHH, RHW, and RHW-2 without outer covering. 2009 Edition NATIONAL ELECTRICAL CODE 70-761 Annex C: Tables ANNEX C Table C.12(A) Maximum Number of Compact Conductors in Type EB, PVC Conduit (Bused on Table 1, Chapter 9) COMPACT CONDUCTORS Conductor Metric Designator(Trade Size) Size (AWGI 53 78 91 103 129 155 T�Pe kcmil) (2) (3) (3112) (4) (5) (6) THW, 8 30 68 89 113 174 247 THW-2, 6 23 52 69 87 134 191 THHW 4 17 39 51 65 100 143 2 13 29 38 48 74 105 l 9 20 26 34 52 74 110 8 17 23 29 45 64 210 6 15 19 24 38 54 310 5 12 16 21 32 46 410 1 4 10 14 17 27 38 250 3 8 11 14 21 30 300 3 7 9 12 19 26 350 3 6 8 11 17 24 400 2 6 7 10 15 21 500 1 5 6 8 12 I8 600 l 4 5 6 10 14 700 1 3 4 6 9 13 750 l 3 4 5 8 12 900 l 3 4 5 7 10 1000 l 2 3 4 7 9 THHN, 8 — — — — — THWN, 6 34 77 100 128 196 279 THWN-2 4 21 47 62 79 121 172 2 15 34 44 57 87 124 1 11 25 33 42 65 93 IM 9 22 28 36 56 79 210 8 18 23 30 46 65 310 6 15 20 25 38 55 410 5 12 16 20 32 45 250 4 10 13 16 25 35 300 4 8 11 14 22 31 350 3 7 9 12 19 27 400 3 6 8 11 17 24 500 2 5 7 9 14 20 600 1 4 6 7 11 16 700 1 4 5 6 10 14 750 1 4 5 6 9 14 900 3 4 5 7 10 IWO 1 3 3 4 7 10 XHHW, 8 39 88 115 1.16 225 320 XHHW-2 6 29 65 85 109 167 238 4 21 47 62 79 121 172 2 15 34 44 57 87 124 l 11 25 33 42 65 93 110 9 22 28 36 56 79 210 8 18 24 30 47 67 310 6 15 20 25 38 55 410 5 12 16 21 32 46 250 4 10 I3 17 26 37 300 4 8 11 14 22 31 350 3 7 10 12 19 28 400 3 7 9 11 17 25 500 2 5 7 9 14 20 600 1 4 6 7 11 16 700 1 4 5 6 10 14 750 1 3 5 6 9 13 900 1 3 4 5 7 10 1000 1 3 4 5 7 10 Delinition: Compact 5tranding is the result of a manufacturing process where the standard conductor is compressed to the extent that the interstices (voids between strand wires)are virtually eliminated. 70-762 NATIONAL ELECTRICAL CODE 2008 Edition ANNEX D Annex D: Examples Annex D Examples This annex is not a part of the requirements of this NFPA Calculated Load ror Neutral document but is included for informational purposes ally. 14,550 VA-240 V=60.6 A Selection of Conductors. In the following examples, the results are Example D1(b) One-Family Dwelling generally expressed in amperes(A).To select conductor sizes,refer to the 0 through 2000 volt (V) ampacity tables of Article 310 and the rules of 310.15 that pertain Assume same conditions as Example No.D(a),plus addition of one 6-A, Voltage. For uni form application of Articles 210, 215, and 220, a 230-V, room air-conditioning unit and one 12-A, 115-V, room air- these[plies. nominal voltage of 120, 1201240,240,and 208Y1120 V is used in calcu- conditioning unit* one 8-A, 115-V. rated waste disposer, and one I0-A, lating the ampere load on the conductor. 120-V, rated dishwasher. See Article 430 for general motors and Article Fractions of an Ampere. Except where the calculations result in a 440, Part VII, for air-conditioning equipment. Motors have nameplate major fraction of an ampere(0.5 or larger),such fractions are permitted to ratings of 115 V and 230 V for use on 120-V and 240-V nominal voltage be dropped. systems. Power Factor. Calculations in the following examples are based, for (For feeder neutral, use larger of the two appliances for unbalance.) convenience,on the assumption that all loads have the same power factor From Example DI(a), feeder current is 78 A(3-wire,240 V). (PF). Line A Neutral Line B Ranges. For the calculation of the range loads in these examples, Column C of Table 220.55 has been used. For optional methods, see Amperes from Example DI(a) 78 61 78 Columns A and B of Table 220.55.Except where the calculations result in One 230-V air conditioner 6 — 6 a major fraction of a kilowatt(0.5 or larger),such fractions are permitted One 115-V air conditioner and 12 12 10 to be dropped. 120-V dishwasher SI Units.For metric conversions,0.093 mx= 1 ft'and 0.3048 in= t ft. One 115-V disposer — 8 8 25%of largest motor fsee 3 3 2 Example Dl(a) One-Family Dwelling 430.24) The dwelling has a floor area of 1500 ft',exclusive of an unfinished cellar 'fatal amperes per line 99 84 104 not adaptable for future use, unfinished attic, and open porches. Appli- ances are a 12AW range and a 5.5-kW, 240-V dryer.Assume range and dryer kW ratings equivalent to kVA ratings in accordance with 220.54 and Therefore,the service would be rated 110 A. 220.55. Example D2(a) Optional Calculation for One-Family Calculated Load[see 220.401 Dwelling, Heating Larger Than Air Conditioning General Lighting Load: 1500 fti at 3 VA per ft'=4500 VA (see 220,821 Minimum Number of Branch Circuits Required[see 210.1](A)] The dwelling has a floor area of 1500 ft2,exclusive of an unfinished cellar General Lighting Load: 4500 VA; 120 V=37.5 A not adaptable for future use, unfinished attic, and open porches. It has a This requires three I5-A,2-wire or two 20-A,2-wire circuits. 12-kW range, a 2.5-kW water heater, a 1.2-kW dishwasher. 9 kW of electric space heating installed in five rooms,a 5-kW clothes dryer,and a Small Appliance Load:Two 2-wire, 20-A circuits[see (2)] (C)(I)] 6-A,230-V,room air-conditioning unit.Assume range,water heater.dish- Laundry Load:One rcwire, 20-A circuit-see circuit( o additional washer,space heating,and clothes dryer kW ratings equivalent to kVA. Bathroom Branch Circuit:One 2-wire,20-A circuit(nv additional toad calculation is required for this circuit)[see 210.1](C)(3)] Air Conditioner kVA Calculation Minimum Size Feeder Required-see 220.401 6 A x 230 V_ 1000= 1.38 kVA General Lighting 4,500 VA This 1.38 kVA [item 1 from 220.82(C)] is less than 40% of 9 kVA of Small Appliance 3,000 VA separately controlled electric heat [item 6 from 220.82(C)], so the 1.38 Laundry 1,500 VA kVA need not be included in the service calculation. Total 9,000 VA General Load 3000 VA at 100% 3,000 VA 9000 VA-3000 VA=6000 VA at 35% 2,100 VA 1500 ftz at 3 VA 4,500 VA Two 20-A appliance outlet circuits at 1500 VA each 3,000 VA Net Load 5,100 VA Laundry circuit 1,500 VA Range(see Table 220.55) 8,000 VA Range(at nameplate rating) 12,000 VA Dryer Load(see Table 220.54 ) 5,500 VA Water heater 2,500 VA Dishwasher 1,200 VA Net Calculated Load 18,600 VA Clothes dryer 5,000 VA Net Calculated Load for 1201240-V,3-wire,single-phase service or feeder Total 29,700 VA 18,600 VA_240 V=77.5 A Sections 230.42(B)and 230.79 require service conductors and disconnect- Application or Demand Factor[see 220.82(8)1 ing means rated not less than 100 amperes. First 10 kVA of general load at 100% 10,000 VA Calculation for Neutral for Feeder and Service Remainder of general load at 40% 7,880 VA (19.7kVAx0.4) Lighting and Small-Appliance Load 5.100 VA Range: 9000 VA at 70%(see 220.61) 500 VA Total of general load 17,880 VA Dryer:5500 VA at 70`90(see 220,61) 3,850 VA 9 kVA of heat at 40%(9000 VA x 0.4)= 300 VA Total 14,550 VA Total 21,480 VA 2009 Edition NATIONAL ELECTRICAL CODE 70-763 Annex D: Examples ANNEX D Calculated Load for Service Size 1500 fr'al 3 VA 4,500 VA VA 2L48 kVA=21,48(1 Three 20-A circuits at 1500 VA 4,500 VA 21.480 VA_240 V=89.5 A Subtotal 9,000 VA 3000 VA at 100%r 3,000 VA Therefore,the minimum service rating would be 100 A in accordance with 9000 VA--3000 VA=6(x10 VA at 3517r 2,100 VA 230.42 and 230,79, Feeder Neutral Load,per 220.61 Subtotal 5.100 VA 1500 ft'at 3 VA 4,500 VA Three 20-A circuits at 1500 VA 4,500 VA Two 4-kVA ovens plus one 5.I-kVA cooking unit= 13.1 kVA.Table 220.55 permits 55% demand factor or 13.1 kVA x 0.55=7.2 kVA feeder Total 9,000 VA capacity. 3000 VA at 100%r 3,000 VA 9000 VA-3000 VA=6000 VA at 359 2,100 VA Subtotal from above 5,100 VA Ovens and cooking unit:7200 VA x 70% for neutral load 5,040 VA Subtotal 5,100 VA Clothes washer/dryer:5 kVA x 70% for neutral load 3,500 VA Range: 8 kVA at 70%r 5,600 VA Dishwasher 1,200 VA Clothes dryer:5 kVA at 709 3,500 VA Total 11,840 VA Dishwasher 1,200 VA Total 15,400 VA Calculated Load for Neutral Calculated Load for Neutral 14,840 VA 240 V=61.83 A(use 62 A) 15,400 VA_240 V=64.2 A Example D2(c) Optional Calculation for One-Family Example D2(b) Optional Calculation for One-Family Dwelling with Heat Pump (Single-Phase,2401120-Volt Dwelling,Air Conditioning Larger Than Heating Service) {see 220.82} (.see 220,82(A)and 220.82(C)] The dwelling has a floor area of 2000 ft',exclusive of an unfinished cellar The dwelling has a flax area of 1500 W.exclusive of an unfinished cellar not adaptable for future use, unfinished attic, and open porches. It has a not adaptable for future use.unfinished attic,and open porches.It has two 12-kW range,a 4.5-kW water heater,a 1.2-kW dishwasher,a 5-kW clothes 20-A small appliance circuits, one 20-A laundry circuit, two 4-1,W wall- dryer,and a 21/:-tun(24-A)heat pump with 15 kW of backup heat. mounted ovens,one 5.l-kW counter-mounted cooking unit,a 4.5-kW wa- ter heater,a 1.2-kW dishwasher,a 5-kW combination clothes washer and Heat Pump kVA Calculation dryer, six 7-A,230-V room air-conditioning units, and a 1.5-kW perma- 24 A x 240 V_ 1000=5.76 kVA nently installed bathroom space heater. Assume wall-mounted ovens, counter-mounted cooking unit,water heater,dishwasher,and combination This 5.76 kVA is less[ban 15 kVA of the backup heat:therefore,the heat clothes washer and dryer kW ratings equivalent to M. pump load need not be included in the service calculation[see 220.82(C)]. Air Conditioning kVA Calculation General Load Total amperes=6 units x 7 A=42 A 2000 ft'at 3 VA 6,000 VA 42 A x 240 V_ 1000= 10.08 kVA(assume PF= 1.0) Two 20-A appliance outlet circuits at 3,000 VA Load Included at 100% 15(x}VA each Laundry circuit 1,500 VA Air Conditioning: Included below[.see itent I in 220.82(C)] Range(at nameplate rating) 12,000 VA Space Heater: Omit[see hero 5 in 220.82(C)] Water heater 4,500 VA Dishwasher 1,200 VA General Load Clothes dryer 5,0W VA 1500 ft'at 3 VA 4,500 VA Two 20-A Small-appliance Subtotal general load 33,200 VA circuits at 1500 VA each 3,000 VA First 10 kVA at 100% 10,000 VA Laundry circuit 1,500 VA Remainder of general load at 40%r 9,280 VA Two ovens 8,000 VA (23,200 VA x 0.4) One cooking unit 5,100 VA Water heater 4,500 VA Total net general load 19,280 VA Dishwasher 1,200 VA Washer/dryer 5,000 VA Hcat Pump and Supplementary Heat* Total general load 32,800 VA 240 V x 24 A=5760 VA First 10 kVA at 1004 10,000 VA Remainder at 40%r 15 kW Electric Heat: (22.8 kVA x 0.4 x 10001 9,120 VA 5760 VA+(15,000 VA x 65%n)=5.76 kVA+9.75 kVA= 15.51 kVA Subtotal general load 19,120 VA *If supplementary heat is not on at same time as heal pump,heat Air conditioning 10,060 VA pump kVA need not be added to total. Totals Total 29,200 VA Net general load 19,280 VA Heat pump and supplementary heat 15,510 VA Calculated Load for Service Total 34,790 VA 29,200 VA+240 V= 122 A(service rating) Calculated Load for Service Feeder Neutral Load,per 220.61 34.79 kVA x 1000_240 V= 144.96 A Assume that the two 4-kVA wall-mounted ovens are supplied by one branch Therefore,this dwelling unit would be permitted to be served by a 150-A circuit,the 5.1-kVA counter-mounted cooking unit by a separate circuit. service, 70-764 NATIONAL ELECTRICAL CODE 2008 Edition ANNEX D Annex D: Examples Example D3 Store Building Minimum Size Feeders (or Service Conductors)Required Isee 215.2. 230.42(A)1 A store 50 ft by 60 ft,or 3000 ft'.has 30 ft of show window.There are a For 1201240 V,3-wire system, total of 80 duplex receptacles. The service is 1201240 V, single phase 3-wire service.Actual connected lighting load is 8500 VA. 32,450 VA;240 V= 135 A Calculated Load(see 220.40) Service or feeder conductor is 1/0 Cu per 215.3 and Table 310.16 (with 75°C terminations). Noncontinuous Loads Receptacle Load(see 220.44) Example D3(a) Industrial Feeders in 80 receptacle,at 180 VA 14,400 VA a Common Raceway 10,000 VA at 100% 10,000 VA 14,400 VA- 10,000 VA=4400 at 50% 2,200 VA An industrial multi-building facility has its service at the rear of its main building,and then provides 480YI277-volt feeders to additional buildings Subtotal 12,200 VA behind the main building in order to segregate certain processes. The Continuous Loads facility supplies its remote buildings through a partially enclosed access General Lighting" 3000 ft2 at 3 VA per ft' 9,000 VA condor that extends from the main switchboard rearward along a path Show Window Lighting Load that provides convenient access to services within 15 m (50 ft) of each 30 ft at 200 VA per ft lsee 220.14(G)1 6,((x)VA additional building supplied.Two building feeder-,share a common race- Outside Sign Circuit Isee 220.14(F)l 1,200 VA way for approximately 45 m (150 ft)and run in the access corridor along Subtotal 16,2{x)VA with process steam and control and communications cabling.The steam Subtotal from noncontinuous 12.00 VA raises the ambient temperature around the power raceway to as much as 35°C.At a tee fitting,the individual building feeders then run to each of the two buildings involved.The feeder neutrals are not connected to the Total noncontinuous loads+ equipment grounding conductors in the remote buildings.All distribution continuous loads= 28,400 VA equipment terminations are listed as being suitable for 75°C connections. *In the example,125%of the actual connected lighting load(8500 VA x 1.25 Each of the two buildings has the following loads: = 10,625 VA)is less than 125%of the load from Table 220.12,so the mini- Lighting, 11.600 VA, comprised of electric-discharge luminaires con- mum lighting load from Table 220.12 is used in the calculation.Had the actual netted at 277 V lighting load been greater than the value calculated from Table 220.12, 125% Receptacles, 22 125-volt, 20-ampere receptacles on general-purpose of the actual connected lighting load would have been used. branch circuits, supplied by separately derived systems in each of the buildings Minimum Number of Branch Circuits Required 1 Air compressor,460 volt,three phase,7.5 hp General Lighting: Branch circuits need only be installed to supply the 1 Grinder,460 volt,three phase, 1.5 hp actual connected load Isee 210.11(8)1. 3 Welders, AC transformer type (nameplate: 23 amperes, 480 volts, 8500 VA x 1.25= 10,625 VA 60 percent duty cycle) 10.625 VA_240 V=44 A for 3-wire, 1201240 V 3 Industrial Process Dryers,480 volt,three phase,15 kW each(assume The lighting load would be permitted to he served by 2-wire or 3-wire, continuous use throughout certain shifts) 15-or 20-A circuits with combined capacity equal to 44 A or greater for Determine the overcurrem protection and conductor size for the feeders in 3-wire circuits or 88 A or greater for 2-wire circuits.The feeder capacity the common raceway,assuming the use of XHHW-2 insulation(90°C): as well as the number of branch-circuit positions available for lighting circuits in the panelboard must reflect the full calculated load of 9000 VA Calculated Load [Note:For reasonable precision,volt-ampere calculations x 1.25= 11.250 VA. are carried to three significant figures only: where loads ure converted to Show Window amperes,the results are rounded to the nearest ampere[see 220,5(B)11, 6000 VA x 1.25=7500 VA Noncontinuous Loads 7500 VA_240 V=31 A for 3-wire, 120/240 V Receptacle Load(see 220.44) 22 receptacles at 180 VA 3,960 VA The show window lighting is permitted to be served by 2-wire or 3-wire Welder Load [see 630.11(A),Table circuits with a capacity equal to 31 A or greater for 3-wire circuits or 62 A 630.11(A)I or greater for 2-wire circuits. Each welder:480V x 23A x 0.78=8,610 Receptactes required by 210.62 are assumed to be included in the VA receptacle load above if these receptacles do not supply the show window All 3 welders: [see 630.11(B)l (demand lighting load. factors 100%, INK,85% re>peciivcly) 8,610 VA+8,610 VA+7,320 VA= 24,500 VA Receptacles Subtotal,Noncontinuous Loads 28,500 VA Receptacle Load:14,400 VA_240 V=60 A for 3-wire, 1201240 V Motor Loads(see 430.24,'fable 430.250) The receptacle load would be permitted to be served by 2-wire or Air compressor. 11 A x 480 V x v`.3= 9,150 VA 3-wire circuits with a capacity equal to 60 A or greater for 3-wire circuits Grinder,3 A x 480 V x d3= 2,490 V.A or 120 A or greater for 2-wire circuits. Largest motor,additional 25%: 2,290 VA Minimum Size Feeder(or Service) Overcurrent Protection Isee 215.3 or 230.901 Subtotal,Motor Loads 13,900 VA Subtotal noncontinuous[Dads 12,20()VA By using 430.24,the motor loads and the noncontinuous loads can be Subtotal continuous load at 125r7r 20.250 VA combined for the remaining calculation. (16,200 VA x 1.25) Subtotal for load calculations, Total 32,450 VA Noncontinuous Loads 42,400 VA Continuous Loads General fighting 11,600 VA 32.450 VA_240 V= 135 A 3 Industrial Process Dryers 15 kW each 45,000 VA The next higher standard size is 150 A(see 240.6). Subtotal,Continuous Loads: 56,600 VA 2008 Edition NATIONAL ELECTRICAL CODE 70-.765 Annex D. Examples ANNEX D Overcurrent protection (see 215.3) That calculation is(11,600 VA z 277V)=42 amperes,to be evaluated under The overcurrem protective device must accommodate 125% of the con- the 75°C column of Table 310.16.The minimum size of the neutral might sinuous load,plus the noncominuous load: seem to be 8 AWG,but that size would not he Sufficient to be depended upon in the event of a lute-to-neutral Short Circuit[see 21,5.2fAN1),seeond parr. Continuous load 56,600 VA graph).Therefore,since the minimum size equipment grounding conductor Noncontinuous load 42,400 VA for a 150 ampere circuit,as covered in Table 250.122,is 6 AWG,that is the minimum neutral size required for this feeder. Subtotal,actual load [actual load in amperes] 99,000 VA Example D4(a) Multifamily Dwelling 199,000 VA_(480V x-J3)= 119 A] (25070 of 56,600 VA)(See 215.3) 14,200 VA A multifamily dwelling has 40 dwelling units. Total VA 113,200 VA Meters are in Iwo banks of 20 each with individual feeders to each dwell- ing unit. Conversion to amperes using three significant figures: 113,200 VA/(480V x d = 136 A One-half of the dwellin g units are equipped with electric ranges not ex- Minimum size overcurrent protective device: 130 A ceeding 12 kW each.Assume range kW rating equivalent to kVA rating in Minimum standard size overcurrent protective device(see 240.6): 150 accordance with 220.55.Other half of ranges are gas ranges. amperes Area of each dwelling unit is 840 ftZ. Where the overcurrent protective device and its assembly are listed Laundry facilities on premises are available to all tenants.Add no circuit for operation at 100 percent of its rating, a 125 ampere overcurrent pro- to individual dwelling unit. tective device would be permitted.However,overcurrent protective device Calculated Load for Each Dwelling Unit(see Article 220) assemblies listed for 100 percent of their rating are typically not available General Lighting: 840 ft'-at 3 VA per ft2=2520 VA at the 125-ampere rating.(See 215.3 Eveeprion.) Ungrounded Appliance: Electric range(see 220.55)=9000 VA Ungrounded Feeder Conductors Minimum Number of Branch Circuits Required for Each Dwelling The conductors must independently meet requirements For (1) terming- Unit[see 210.11(A)1 tions,and(2)conditions of use throughout the raceway run. General Lighting Load: 2520 VA 120 V= 21 A or two 15-A, 2-wire Minimum size conductor at the overcument device termination (see circuits:or two 20-A.2-wire circuits 110.14(0and 215.2(A)(1),ruing 75°C anrparity column in Table 310.161: Small-Appliance Load:Two 2-wire circuits of 12 AWG wire 110 AWG. [see 210.11(C)(1)1 Minimum size conductors in the raceway based on actual load [see Range Circuit: 8000 VA _ 240 V = 33 A or a circuit of two 8 AWG Article 100.Ampacity,and 310.15(B)(2)(a)and correction factors to Trrhle conductors and one 10 AWG conductor per 210.19(A)(3) Table 310.16]: 99,000 VA/0.7 0.96= 147,0(N}VA Minimum Size Feeder Required for Each Dwelling Unit(see 215.2) / Calculated Load(see Article 220): 170%=310.15(13)(2)(a)l & (0.96=Correction factors to Table 310.16) General Lighting 2,520 VA Conversion to amperes: Small Appliance(two 20-ampere circuits) 3.000 VA 147,000 VA/(480V x vt3)= 177 A Subtotal Calculated Load(without ranges) 5,520 VA Note that the neutral conductors are counted as current-carrying conduc- tors[see 310.15(B)(4)(r)[in this example because the discharge lighting has substantial nonlinear content.This requires a 210 AWG conductor based on Application of Demand Factor(see Table 220.42) the 90°C column of Table 310.16 Therefore,the worst case is given by the First 300()VA at 100% 3,0IX)VA raceway conditions, and 210 AWG conductors must be used. If the utility 5520 VA-3000 VA=2520 VA at 35'7r 882 VA corridor was at normal temperatures[(30°C(86°17)],and if the lighting at each Net Calculated Load(without ranges) 3.882 VA building were supplied from the local separately derived system(thus requir- Range Load 8,000 VA ing no neutrals in the supply feeders)the raceway result(99,000 VA 10.8= Net Calculated Load(with es) 11,882 VA 124,000 VA: 124,000 VA 1(480V x q3)= 149 A,or a 1 AWG conductor C ran es) 90°C)could not be used because the termination result(110 AWG based on the 75°C column of'lable 310.16)would become the worst case,requiring the Size of Each Feeder(see 215.2) larger conductor. In every case,the overcurrent protective device shall provide overcurrent For 1201240-V, 3-wire system (without ranges) protection Fur the feeder conductors in accordance with their ampacity as Net calculated load of 3882 VA_240 V= 16.2 A provided by this Code(see 24(1.4).A 90°C 210 AWG conductor has a Table For 1201240-V, 3-wire system(with ranges) 3 10.16 ampacity of 195 amperes.Adjusting for the conditions of use(35°C Net calculated load, I I,R82 VA; 240 V=49.5 A ambient temperature,8 current-carrying conductors in the common raceway), 195 amperes x 0.96 x 0.7= 131 A Feeder Neutral The 150-ampere circuit breaker protects the 210 AWG feeder conduc- Lighting and Small-Appliance Load 3,882 VA tors, because 240.4(8) permits the use of the next higher standard size Range Load: 8WO VA at 70% (see 220.61) 5,600 VA overcurrent protective device. Note that the feeder layout precludes the (only for apartments with electric range) 5,600 VA application of 310.15(A)(2)Exception. Net Calculated Load(neutral) 9,482 VA Feeder Neutral Conductor(see 220,61) Because 210.11(B) does not apply to these buildings, the load cannot be Calculated Load for Neutral assumed to be evenly distributed across phases.Therefore the maximum im- 9482 VA�240 V=39.5 A balance must be assumed to be the full lighting toad in this case,or 11,600 VA. (11,600 VA 1 277V=42 amperes.)The ability of the neutral to return Minimum Size Feeders Required from Service Equipment to Meter fault current[see 250.32(B)Erceptirm(2)[is not a factor in this calculation. Bank(For 20 Dwelling Units-10 with Ranges) Bbcauge the neutral runs between the main switchboard and the build- ing panelboard, likely terminating on a bulbar at both locations,and not Total Calculated Load: On oVerCnrrent devices, the effects of continuous loading can be disre- Lighting and Small Appliance garded in evaluating its terminations Isere 2112(A)(1)Exception No. 21. 20 units x 5520 VA 110,400 VA 70-766 NATIONAL ELECTRICAL CODE 2008 Edition ANNEX D Annex D: Examples Application of Demand Factor Example D4(b) Optional Calculation for First 3000 VA at 100% Multifamily Dwelling 110,400 VA-3000 VA= 107.400 VA at 35% 3,000 VA 37,590 VA A multifamily dwelling equipped with electric cooking and space heating or air conditioning has 40 dwelling units. Net Calculated Load 40,590 VA Meters are in two banks of 20 each plus house metering and individual Range Load: 10 ranges(not over 12 kVA) 25,000 VA feeders to each dwelling unit. (see Col. C, Table 220.55. 25 M Each dwelling unit is equipped with an electric range of 8-kW name- Net Calculated Load(with ranges) 65,590 VA plate rating,four 1.5-kW separately controlled 240-V electric space heat- ers, and a 2.5-kW, 240-V electric water heater, Assume range, space heater,and water heater kW ratings equivalent to kVA. Net calculated load For 120/240 V,3-wire system, A common laundry facility is available to all tenants!see 210.52(F), 65,540 VA_240 V=273 A Exception No, 11. Feeder Neutral Area of each dwelling unit is 840 fr'. Lighting and Small-Appliance Load 40,590 VA Calculated Load for Each Dwelling Unit(see Article 220) Range Load: 25,000 VA at 70%[see 220.61(B)l 17,500 VA Calculated Load(neutral) 55,090 VA General Lighting Load: 840 112 at 3 VA per ft' 2,520 VA Electric range 8,000 VA Calculated Load for Neutral Electric heat: 6 kVA(or air conditioning 6,000 VA 58,090 VA 240 V=242 A if larger) Further Demand Factor[220.6](B)J Electric water heater 2,500 VA 200 A at 100% 200 A 242 A--200 A=42 A at 70% 29 A Minimum Number of Branch Circuits Required for Each Dwelling Net Calculated Load(neutral) 229 A Unit General Lighting Load: 2520 VA_ 120 V = 21 A or two 15-A, 2-wire circuits,or two 20•A. 2-wire circuits Minimum Size Main Feeders(or Service Conductors)Required Small-Appliance Load:Two 2-wire circuits of 12 AWG[see 210.1](C)(1)1 (Less House Load) (For 40 Dwelling Units-20 with Ranges) Range Circuit fSee Table 220.55, Column B): Total Calculated Load: 8000 VA x 80% _240 V=27 A on a circuit of three Lighting and Small-Appliance Load 10 AWG conductors per 210.19(A)(3) 40 units x 5520 VA 220,800 VA Space Heating: 6000 VA_240 V=25 A Number of circuits(see 210.11) Application of Demand Factor Minimum Size Feeder Required for Each Dwelling Unit(see 215.2) (from Table 220.41) Calculated Load flee Article 220): First 3000 VA at 100% 3,000 VA General Lighting 2,520 VA Next 120,000 VA-3000 VA= 1 17,000 VA at 35% 40,950 VA Small Appliance(two 20-A circuits) 3,000 VA Remainder 220,800 VA-- 120,000 VA= 100,800 VA at 25,200 VA 25% Subtotal Calculated Load(without range 5,520 VA Net Calculated Load 69,150 VA and space heating) Range Load: 20 ranges(less than 12 kVA) (see Cal. C Table 220.55) 35,000 VA For 1201240-V,3-wire system Net Calculated Load 104,150 VA Application of Demand Factor First 3000 VA at IW% 3,000 VA Net calculated load of 104,150 VA;240 V=434 A 5520 VA-3000 VA=2520 VA at 3501r 882 VA Net Calculated Load 3,882 VA Feeder Neutral (without range and space heating) Range 6,400 VA Lighting and Small-Appliance Load 69,150 VA Space Heating flee 220.51) 6,000 VA Range: 35,000 VA at 7017, [see 220.61(B)] 24,500 VA Water Heater 2,500 VA Calculated Load(neutral) 93,650 VA Net Calculated Load(for individual dwelling unit) 18,782 VA 93,650 VA-:240 V=390 A Size of Each Feeder Further Demand Factor[see 220.61(B)l For 1201240-V,3-wire system, Net calculated load of 1 8,782 VA_240 V=78 A 200 A at 100% 200 A Feeder Neutral(see 220.61) 390 A-200 A= 190 A at 70% 133A Net Calculated Load{neutral) 333 A Lighting and Small Appliance 3,882 VA Range Load: 6400 VA at 70%[,see 220.61(B)J 4,480 VA Space and Water Heating(no neutral):240 V 0 VA [See Table 310.16 through Table 310,21, and 310,15(B)(2)and(B)(4).] Net Calculated Load(neutral) 8,362 VA 2008 Edition NATIONAL ELECTRICAL CODE 70-767 Annex D: Examples ANNEX D Calculated Load for Neutral 107,650 VA 240 V=449 A 8362 VA 240 V=35 A Further Demand Factor(see 220.61(B)l Minimum Size Feeder Required from Service Equipment to Meter Bank(For 20 Dwelling Units) First 200 A at 1(H)% 200 A Balance:449-200 A=249 A at 70% 174 A Total Calculated Load: Lighting and Small-Appliance Load Total 374 A 20 units x 5520 VA 110.400 VA Water and Space Heating Load 20 units x 8500 VA 170,000 VA Range Load: 20 x 8000 VA 160,000 VA Example D5(a) Multifamily Dwelling Served at Net Calculated Load(20 dwelling units) 440,400 VA 2081:/120 Volts, Three Phase Net Calculated Load Using Optional Calculation(see All conditions and calculations are the same as for the mullifaimiiy dwell- Table 220.84) 440,400 VA x 0.38 167,352 VA ing[Example D4(a)]served at 120/240 V.single phase except as follows: Service to each dwelling unit would he two phase legs and neutral. 167,352 VA_240 V=697 A Minimum Number or Branch Circuits Required for Each Dwelling Minimum Size Main Feeder Required (Less House Load) (For 40 Unit(see 210.11) Dwelling Units) Range Circuit: 8000 VA _ 208 V = 38 A or a circuit of two 8 AWG Calculated Load: conductors and one 10 AWG conducior per 210.19(A)(3) Lighting and Small-Appliance Load Minimum Size Feeder Required for Each Dwelling Unit(see 215.2) 40 units x 5520 VA 220,800 VA For 12{)1208-V,3-wire system (without ranges), Water and Spare Beating Load 340,000 VA Net calculated load of 3882 VA_2 legs� 120 V/leg= 16.2 A 40 units x 8500 VA For 1201208-V, 3-wire system (with ranges), Range:40 ranges x 8000 VA 3200)0 VA Net calculated load(range) of 8000 VA_208 V=38.5 A Net Calculated Load(40 dwelling units) 880,800 VA Total load(range+lighting)=38.5 A.+� 16.2 A=54.7 A Feeder neutral:(range)of 8000 VA x 707 =56M VA_208 V=26.9 A Total load: (range+lighting)=26.9 A+ 16.2 A=43.1 A Net Calculated Load Using Optional Calculation(see Table 220.84) Minimum Size Feeders Required from Service Equipment to Meter 880,800 VA x 0.28=246,624 VA Bank(For 20 Dwelling Units-10 with Ranges) 246,624 VA�240 V= 1028 A For 208Y/120-V,3-phase,4-wire system, Ranges:Maximum number between any two phase legs=4 Feeder Neutral Load for Feeder from Service Equipment to Meter 2 x 4=8. Bank(For 20 Dwelling Units) Table 220.55 demand=23,000 VA Lighting and Small-Appliance Load Per phase demand=23,000 VA s 2= 11,500 VA 20 units x 5520 VA 110,400 VA Equivalent 3-phase load= 34,500 VA First 3000 VA at 100% 3.000 VA Net Calculated Load(total): 110,400 VA-3000 VA= 107,400 VA 37,590 VA at 35% 40,590 VA+34,500 VA=75,090 VA 75,090 VA_(208 V1(1.732)=208.4 A Net Calculated Load 40,590 VA Feeder Neutral Size 20 ranges: 35,000 VA at 70% 24,500 VA Net Calculated Lighting and Appliance Load& Equivalent Range Load- /see Table 220.55 and 220.61(B)J 40.590 VA+(34,500 VA at 701/r)=64,700 VA Total 65.090 VA Net Calculated Neutral Load: 64,700 VA_(208 V)j 1.732)= 179.7 A 65,090 VA_240 V=271 A Minimum Size Main Feeder (Less House Load) (For 40 Dwelling Further Demand Factor/.see 220.61(B)I Units-20 with Ranges) For 20BY/I 20-V,3-phase.4-wire system, First 200 A at 100% 200 A Ranges: Balance: 271 A--200 A=71 A at 70% 50 A Maximum number between any two phase legs=7 2x7= 14. Total 250 amperes Table 220.55 demand=29,000 VA Per phase demand=29,000 VA_2= 14,500 VA Equivalent 3-phase load=43,500 VA Feeder Neutral Load of Main Feeder (Less House Load) (For 40 Net Calculated Load(total): Dwelling Units) 69,150 VA+43,500 VA= 1 12,650 VA Lighting and Small-Appliance Load 112,650 VA_(208 V)(1.732)=312.7 A 40 units x 5520 VA 220,800 VA Main Feeder Neutral Size: First 3000 VA at 100% 3,000 VA Next 120,000 VA-3000 VA= 117,000 VA at 35% 40,950 VA 69,150 VA+(43,500 VA at 70%)=99,600 VA Remainder 220,800 VA- 120,000 VA= 100,800 VA at 25,200 VA 99.600 VA (208 V)(1.732)=276.5 A 25% Further Demand Factor(see 220,61) Net Calculated Load 69,150 VA 40 ranges:55,000 VA at 70% 38,500 VA 200 A at 100% 200,0 A (see Table 220.55 and 220.61(B)] 276.5 A-200 A=76.5 A at 70% 53.6 A Total 107,650 VA Net Calculated Load(neutral) 253,6 A 70-768 NATIONAL ELECTRICAL CODE 2008 Edition ANNEX D Annex D: Examples Example D5(b) Optional Calculation for Multifamily From Table 220.55.Column C,the demand for 30 range,of 12-kW rating Dwelling Served at 208Y/120 Volts,Three Phase is 15 kW+30(1 kW x 30 ranges)=45 kW. 13.6 kW exceeds 12 kW All conditions and calculations are the same as for Optional Calculation by 1.6 kW(use 2 kW). for the Multifamily Dwelling[Example D4(b)]served at 1201244)V,single 5%x 2= 10%(5% increase for each kW in excess of 12 kW) phase except as follows: 45 kW x 10%=4.5 kW increase Service to each dwelling unit would be two phase legs and neutral. 45 kW+4.5 kW=49.5 kW(value to be used in selection of feeders) Minimum Number of Branch Circuits Required for Each Dwelling Example D8 Motor Circuit Conductors, Overload Unit(see 210.11) Protection, and Short-Circuit and Ground-Fault Range Circuit(see Table 220.55, Colrain B):8(X)0 VA at 80%_208 V= Protection (see 240.6, 430.6, 430.22, 430.23, 430.24, 30.7 A or a circuit of two 8 AWG conductors and one 10 AWG 430.32, 430.52, and 430.62, Table 4.30.52, and Table conductor per 210.19(A)(3) 430.250) Space Heating: 6000 VA_208 V=28.8 A Determine the minimum required conductor ampacity.(he motor overload Two 20-ampere,2-pale circuits required, 12 AWG conductors protection.[he branch-circuit short-circuit and ground-fault protection,and Minimum Size Feeder Required for Each Dwelling Unit the feeder protection,for three induction-type motors on a 480-V,3-phase 1201208-V,3-wire circuit feeder,as follows: Net calculated load of 18.782 VA_208 V=90.3 A (a) One 25-hp,460-V, 3-phase, squirrel-cage motor, nameplate full- Net calculated load(lighting line to neutral): load current 32 A, Design H,Service Factor 1.15 (b) Two 30-hp,460-V, 3-phase,wound-rotor motors,nameplate pri- 3882 VA_2 legs_ 120 V per leg= 16.2 amperes mary full-load current 38 A, nameplate secondary full-load cur- Line to line= 14,900 VA_ 208 V=71.6 A rent 65 A,40°C rise. Total load= 16.2 A+71.6 A=87.8 A Conductor Ampacily Minimum Size Feeder Required for Service Equipment to Meter Bank The full-load current value used to determine the minimum required con- (For 20 Dwelling Units) ductor ampacity is obtained from Table 430.250 Isee 430.6rA)j for the Net Calculated Load squirrel-cage motor and the primary of the wound-rotor motors.To obtain 167.352 VA_1208 V)(1.732)=464.9 A the minimum required conductor ampacity,the full-load current is multi- Feeder Neutral Load plied by 1.25 Isee 430-22 and 430.23(A11. For the 25-hp motor, 65.080 VA�(208 V)(1.732)= 180.65 A 34 A x 1.25=42.5 A Minimum Size Main Feeder Required (Less House Load) (For 40 For the 30-horsepower motors. Dwelling Units) 40 A x 1.25=50 A Net Calculated Load 65 A x 1.25=81.25 A Motor Overload Protection 246,624 VA_(208 V)(1.732)=684,6 A Where protected by a separate overload device,the motors are required to Main Feeder Neutral Load have overload protection rated or set to trip at not more than 12511c of the 107.650 VA_(208 V)(1.732)=298.8 A nameplate full-load current Isee 430.6(A)and 430.32(A)(1)]. Further Demand Factor Isee 220.61(B)J For the 25-hp motor. 32 A x 1.25=40,0 A 200 A at 100"/t 200.0 A For the 30-hp motors, 298.8A-200A=98.8Aat70rk 692A 38Ax 1.25=47.5A Where the separate overload device is an overload relay(not a fuse or Net Calculated Load(neutral) 2692 A circuit breaker),and the overload device selected at 125%is not sufficient to start the motor or carry the load, the trip setting is permitted to be increased in accordance with 430.32(C). Branch-Circuit Short-Circuit and Ground-Fault Protection Example D6 Maximum Demand for Range Loads The selection of the rating of the protective device depends on the type of ..(1 �� Table.. .55,Column C.applies to ranges not over 12 kW.The applica- protective device selected, in accordance with 430.52 and Table 430.52. tion of Note I ut ranges over 12 kW(and not over 27 kW)and Note 2 to The following is for the 2�-hp motor. ranges over 83/4 kW(and not over 27 kW) is illustrated in the following (a)Nowime-Delay Fuse:The fuse rating is 3W%x 34 A= 102 A.The next larger standard fuse is 110 A Isee 240.6 and 430.52(C)(1). Et- two examples. reprion No.11.If the motor will not start with a 110-A nontime-delay A.Ranges All the Same Rating(see Table 220.55, Note 1) fuse,the fuse rating is permitted to be increased to 125 A because this Assume 24 ranges,each rated 16 kW, rating does not exceed 400%Isee 430.52(C)(1).Eiceptiun No.2(a)1, From Table 220.55,Column C,the maximum demand for 24 ranges of (b)Time-Delay Fuse:The fuse rating is 1751/c x 34 A=59.5 A.The next 12-kW rating is 39 kW. 16 kW exceeds 12 kW by 4. larger standard fuse is 60 AIsee 240.6 and 430,52(C1(1), Exception No.11.if the motor will not start with a 60-A time-delay fuse,the fuse 5% x 4=20% (5elt increase for each kW in excess of 12) rating is permitted to be increased to 70 A because this rating does not 39 kW x 20e/t =7.8 kW increase exceed 225%[see 430.52(C)(1).Eereption No.2(h)]. 39+7,8=46,8 kW(value to be used in selection of feeders) Feeder Short-Circuit and Ground-Fault Protection B.Ranges of Unequal Rating(see Table 220.55,Note 2) The rating of the feeder protective device is based on the sum of the Assume 5 ranges, each rated 11 kW; 2 ranges,each rated 12 kW; 20 largest branch-circuit protective device(example is 110 A)plus the sum of ranges,each c aced 13.5 kW;3 ranges.each rated 18 kW. the full-load currents of the other motors,or 110 A+40 A+40 A= 190 A.The nearest standard fuse that does not exceed this value is 175 A Isee 5 ranges x 12 kW= 60 kW(use 240.6 and 430.62{A)1. 12 kW for range rated less than 12) 2 ranges x 12 kW= 24 kW Example D9 Feeder Ampacity Determination for 20 ranges x 13.5 kW= 270 kW Generator Field Control (see 215.2, 430.24, 430.24 3 rangeg x 18 kW= 54 kW Ereeptirnt No. 1, 620.13, 620.14, 620.61, and Table 430.22(E)and 620.141 30 ranges,Total kW= 408 kW Determine the conductor ampacity for a 460-V 3-phase,60-Hz ac feeder 408_30 ranges= 13.6 kW!average to be used for calculation) supplying a group of six elevators.The 460-V ae drive motor nameplate 2008 Edition NATIONAL ELECTRICAL CODE 70-769 Annex D: Examples ANNEX D rating of the largest MG set for Line elevator is 40 hp and 52 A, and the Example D111 Feeder Ampacity Determination for remaining elevators each have a 30-hp,40-A, ac drive motor rating for Adjustable Speed Drive Control�.ree 215.2, 430.24, their MG sets. In addition to a motor controller, each elevator has a 620.13, 620.14. 620.61, and Table 430.22(E)] separate motion/operation controller rated 10 A continuous to operate mi- croprocessors,relays,power supplies,and the elevator car door operator. Determine the conductor ampacity for a 4604,3-phase,60-Hz ae feeder The MG sets are rated continuous. supplying a group of six identical elevators. The system is adjustable- Conductor Ampacity.Conductor ampacity is determined as follows: speed SCR do drive. The power transformers are external to the drive (a) Per 620.13(D) and 620.61(B)(1), use Table 430.22(E), for inter- (motor controller)cabinet. Each elevator has a separate motion/operation mittent duty(elevators).For intermittent duty using a continuous controller connected to the load side of the main line disconnect switch rated motor,the percentage of nameplate current rating to be used rated 10 A continuous to operate microprocessors,relays,power supplies, is 1.10%. and the elevator car door operator. Each transformer is rated 95 kVA with (b) For the 30-hp ac drive motor, an efficiency of 90%. 140% x 40 A=56 A. (c) For the 40-hp ac drive motor, Conductor Ampacity 140% x 52 A=73 A. Conductor ampacity is determined as follows: (d) The total conductor ampacity is the sum of all the motor currents: (a) Calculate the nameplate rating of the transformer: (l motor x 73 A)+(5 motors x 56 A)=353 A (e) Per 620.14 and Table 620.14, the conductor (feeder) ampacity 1_ 95 kVA x 1000 y 1��A would he permitted to be reduced by the use of a demand factor. Constant loads are not included(see 6120.14, FPN).For six eleva- f X 460 V X 0,90"' tors, the demand factor is 0.79. The feeder diverse ampacity is, therefore,0.79 x 353 A=279 A. (b) Per 620.13(D), for six elevators, the total conductor ampacity is (f) Per 430.24 and 215.3, the controller continuous current is 125% the sum of all the currents. x 10 A= 12.5 A 6 elevators x 133 A=798 A (g) The total feeder ampacity is the sum of the diverse current and all (c) Per 620.14 and Table 620.14, the conductor (feeder) ampacity the controller continuous current. would be permitted to be reduced by the use of a demand factor. =279 A+(6 elevators x 12.5 A)=354 A Constant loads are not included(.tee 620.13, FPN No.2).For six (h) This ampacity would be permitted to be used to select the wire elevators,the demand factor is 0.79.The feeder diverse ampacity size. is,therefore,0.79 x 798 A=630 A. See Figure D9. (d) Per 430.24 and 215.3, the controller continuous current is 125% x10A= 12.5 A. -------- Machine room (e) The total feeder ampacity is the sum of the diverse current and all To additional elevator the controller constant current. 1,,,w=630 A+(6 elevators x 12.5 A)=705 A (f7 This ampacity would be permitted to be used to select the wire sire. See Figure D10. Example D11 Mobile Home (see 550.18) A mobile home floor is 70 I't by 10 ft and has two small appliance circuits: a 1000-VA,240-V heater;a 200-VA, 120-V exhaust fan;a 400-VA, 120-V To additional elevator dishwasher, and a 7000-VA electric range. m. Lighting and Small-Appliance Load m: Lighting(70 ft x 10 ft x 3 VA per ft=) 2,100 VA Feeder o Motor Small-appliance(1500 VA x 2 circuits) 3,000 VA Panel " controller Laundry(1500 VA x l circuit) 1,500 VA CM Machine m 620.13(A) Subtotal 6,600 VA room First 3000 VA at 100% branch o 3,000 VA circuit 0 Motion Remainder(6600 VA–3000 VA= 1,260 VA panel controller 3600 VA)x 35`k Generator field control system Total 4,260 VA Operation "sat4260 VA_240 V= 17.75 A per leg Amperes per Leg Leg A Leg B ❑ Lighting and appliance-,, 17.75 17.75 To additions[elevator Car Heater(1000 VA_70 240 V) 4.20 4.20 __� Fan(200 VA x 125 + 120 V) 2,OS -- Machine room Dishwasher(400 VA_ 120 V) — 3.30 Range(7000 VA x 0.8_240 V) 23.30 23.30 Figure D9 Generator Field Control. Total amperes per leg 47.33 48.55 Based on the higher current calculated for either leg, a minimum 50-A supply cord would be required. For SI units,0.093 in== 1 ft=and 0.3048 m= I ft. 70-770 NATIONAL ELECTRICAL CODE 2008 Edition ANNEX D Annex D: Examples -----i Machine room Example D12 Park Trailer(see 552.47) To additional elevator Operation A park trailer floor is 40 ft by 10 ft and has two small appliance circuits, controller a {000-VA,240-V heater,a 200-VA, 120-V exhaust fan,a 400-VA, 120-V Operating dishwasher,and a 7000-VA electric range. devices Lighting and Small-Appliance Load Lighting(40 ft x 10 ft x 3 VA per W) 1,200 VA Xg -on Small-appliance(1500 VA x 2 circuits) 3,000 VA Laundry(1500 VA x 1 circuit) 1,500 VA A djustable speed drive system ec or do Subtotal 5,700 VA (A) First 3000 VA at 100% 3,000 VA M Remainder(5700 VA-3000 VA=2700 VAl x 35% 945 VA Optional Total 3,945 VA power Feeder transformer CWT panel r o Car 3945 VA_240 V= 16.44 A per leg N Machine To additional elevator room branch circuit panel Amperes per Leg Leg A Leg B Lighting and appliance 16.44 16.44 Heater(1000 VA_240 V) 4.20 4.20 Fan (200 VA x 125% 120 V) 2.08 — Dishwasher(400 VA- 120 V) — 3.3 Range(7000 VA x 0.8_240 V) 23.30 23.30 Totals 46.02 47.24 To additional elevator y Based on the higher current calculated for either le a minimum 50-A m g Machine roo supply card would be required. For SI units,0.093 m-= 1 ft=and 0.3048 m= 1 ft. Figure D10 Adjustable Speed Drive Control. 2008 Edition NATIONAL ELECTRICAL CODE 70-771 Annex E: Construction Types ANNEX E Annex E Types of Construction This annex is not a parr of the requirements of this NFPA Non-Rated and four for One-Hour Rated to 12 for Fire- document but is included for informational purposes only. Resistive construction. Type III construction has two categories: One-Hour The five different types of construction can be summarized Rated and Non-Rated. Both categories require the structural briefly as follows (see also Table E.2): framework and exterior walls to be of noncombustible ma- Type I is a Fire-Resistive construction type. All struc- terial. One-Hour Rated construction requires all interior tural elements and most interior elements are required to be partitions to be one-hour rated. Non-Rated construction al- noncombustible. Interior, nonbearing partitions are permit- lows nonbearing interior partitions to be of non-rated con- ted to be 1 or 2 hour rated. For nearly all occupancy types, struction. The maximum permitted number of stories for Type I construction can be of unlimited height. multifamily dwellings and other structures is two for Non- Type II construction has 3 categories: Fire-Resistive, Rated and four for One-Hour Rated. One-Hour Rated, and Non-Rated. The number of stories Type IV is a single construction category that provides permitted for multifamily dwellings varies from two for for heavy timber construction. Both the structural frame- Table E.1 Fire Resistance Ratings for Type I Through Type V Construction (hr) Type I Type II Type III Type IV Type V 442 332 222 111 000 211 200 2HH 111 000 Exterior Bearing Walls' Supporting more than one floor, 4 3 2 1 Oh 2 2 2 1 ob columns. or other bearing walls Supporting one floor only 4 3 2 1 Oh 2 2 2 1 oh Supporting a roof only 4 3 l 1 Oh 2 2 2 1 ob Interior Bearing Walls Supporting more than one floor, 4 3 2 1 0 1 0 2 1 0 columns, or other bearing walls Supporting one floor only 3 2 2 1 0 1 0 1 1 0 Supporting roofs only 3 2 1 1 0 1 0 1 l 0 Columns Supporting more than one floor, 4 3 2 1 0 1 0 H 1 0 columns, or other bearing walls Supporting one floor only 3 2 2 1 0 1 0 H 1 0 Supporting roofs only 3 2 1 1 0 1 0 H 1 0 Beams, Girders,Trusses,and Arches Supporting more than one floor, 4 3 2 1 0 1 0 H I 0 columns, or other bearing walls Supporting one floor only 2 2 2 1 0 l 0 H l 0 Supporting roofs only 2 2 1 1 0 l 0 H 1 0 Floor-Ceiling Assemblies 2 2 2 1 0 1 0 H 1 0 Roof-Ceiling Assemblies 2 1'h I 1 0 1 0 H 1 0 Interior Nonbearing Walls 0 0 0 0 0 0 0 0 0 0 Exterior Nonbearing Walls` Oh Oh Oh ob ob ob Oh ob oh ob Source:Table 7.2.1.1 from NFPA 50(Xf.. Building Construction and Safety Codes,2006 edition. H: Heavy timber members. 'See 7.3.2.1 in NFPA 5000. hSee Section 7.3 in NFPA 5000. 'See 7.2.3.2.12, 7.2.4.2.3, and 7.2.5.6.5 in NFPA 5000. 70-772 NATIONAL ELECTRICAL CODE 2008 Edition ANNEX E Annex E: Construction Types Table E.2 Maximum Number of Stories for Types V, IV, and quires a minimum of one-hour rated construction through- III Construction out the building. Non-rated construction allows non-rated interior partitions with certain restrictions. The maximum Maximum Number permitted number of stories for multifamily dwellings and Construction Type of Stories Permitted other structures is 2 for Non-Rated and 3 for One-Hour • Non-Rated 2 Rated. •Non-Rated, Sprinklered 3 • One-Hour Rated 3 The system of designating types of construction also in- • One-Hour Rated, 4 eludes a specific breakdown of the types of construction Sprinklered through the use of arabic numbers. These arabic numbers IV Heavy Timber 4 follow the roman numeral notation where identifying a type IV Heavy Timber, 5 Y� g Yp Sprinklered of construction [for example, Type I(442), Type II(1 l I), Ill Non-Rated 2 Type II1(200)] and indicate the fire resistance rating re- Ut Non-Rated, Sprinklered 3 quirements for certain structural elements as follows: III One-Hour Rated 4 III One-Hour Rated, 5 (1) First arabic number — exterior bearing walls Sprinklered (2) Second arabic number — columns, beams, girders, work and the exterior walls are required to be noncombus- trusses and arches, supporting bearing walls, columns, tible except that wood members of certain minimum sizes or loads from more than one floor are allowed.This construction type is seldom used for mul- (3) Third arabic number — floor construction tifamily dwellings but, if used, would be permitted to be Table E.3 provides a comparison of the types of con- four stories high. struction for various model building codes. [5000: Type V construction has two categories: One-Hour A.7.2.1.11 Rated and Non-Rated. One-Hour Rated construction re- Table E.3 Cross-Reference of Building Construction Types NFPA 5000 1(442) I(332) 11(222) II(111) 11(000) 111(211) 111(200) 1V(2HH) V(111) V(000) UBC — I FR 11 FR 11 1 hr II N III 1 hr III N 1V HT V 1 hr V N B/NBC IA 1B 2A 213 2C 3A 313 4 5A 513 SBC 1 II — IV 1 hr IV UNP V I hr V UNP III VI I hr VI UNP IBC — IA IB IIA IIB IIIA I1113 IV VA VB Source:Table 7.2.L l from NFPA 5000°', Building Construction and Safety Code`, 2(H)6 edition. UBC: Uniform Building Code. FR: Fire rated. N: Nonsprinklered. HT: Heavy timber. B/NBC: National Building Code. SBC: Standard Building Code. UNP: Unprotected. IBC: Lctermutivnal Building Code. 2008 Edition NATIONAL ELECTRICAL COPE 70-773 Annex F: Critical Operations Power Systems ANNEX F Annex F Availability and Reliability for Critical Operations Power Systems; and Development and Implementation of Functional Performance Tests (FPTs) for Critical Operations Power Systems This annex is not a part of the requirements of this NFPA (2) The time required to restore operations following a sys- document but is included for informational purposes only. tem failure or the time required to perform maintenance L Availability and Reliability for Critical Operations to prevent a failure. These times are determined in part Power Systems. Critical operations power systems may by the system's level of maintainability. support facilities with a variety of objectives that are vital (3) The logistics provided to support maintenance of the to public safety. Often these objectives are of such critical system.The number and availability of spares, mainte- importance that system downtime is costly in terms of eco- nance personnel, and other logistics resources (refuel- nomic losses, loss of security, or loss of mission. For those ing,etc.)combined with the system's level of maintain- reasons, the availability of the critical operations power ability determine the total downtime following a system, the percentage of time that the system is in service, system failure. is important to those facilities. Given a specified level of Reliability. Reliability is concerned with the probability availability, the reliability and maintainability requirements and frequency of failures (or lack of failures).A commonly are then derived based on that availability requirement. used measure of reliability for repairable systems is MTBF. Availability. Availability is defined as the percentage of The equivalent measure for nonrepairable items is MTTF. time that a system is available to perform its function(s). Reliability is more accurately expressed as a probability Availability is measured in a variety of ways, including the over a given duration of time, cycles, or other parameter. following: For example,the reliability of a power plant might be stated as MTBF 95 percent probability of no failure over a 1000-hour operat- MTBF+MTTR ing period while generating a certain level of power.Reliabil- ity is usually defined in two ways(the electrical power indus- MTBF = mean time between failures where: try has historically not used these definitions): MTTF = mean time to failure (1) The duration or probability of failure-free performance MTTR = mean time to repair under stated conditions See the following table for an example of how to estab- (2) The probability that an item can perform its intended function for a specified interval under stated conditions limb required availability for critical operation power sys- [For nonredundant items, this is equivalent to the pre- terns: ceding definition (1). For redundant items this is Availability Hours of Downtime" equivalent to the definition of mission reliability.] 0.9 876 Maintainability. Maintainability is a measure of how quickly and economically failures can be prevented through 0.99 87.6 preventive maintenance, or system operation can be re- stored following failure through corrective maintenance. A 0.999 8'76 commonly used measure of maintainability in terms of cor- 0.9999 0.876 rective maintenance is the mean time to repair (MTTR). Maintainability is not the same thing as maintenance. It is a 0.99999 0.0876 design parameter, while maintenance consists of actions to 0999999 0.00876 correct or prevent a failure event. Improving Availability. The appropriate methods to use 0.9999999 0.000876 for improving availability depend on whether the facility is ' being designed or is already in use. For both cases, a'Based on a year of s76o hours. reliability/availability analysis should be performed to de- Availability of a system in actual operations is deter- termine the availability of the old system or proposed new mined by the following: system in order to ascertain the hours of downtime (see the (1) The frequency of occurrence of failures. Failures may preceding table). The AHJ or government agency should prevent the system from performing its function or may dictate how much downtime is acceptable. cause a degraded effect on system operation. Frequency Existing facilities: For a facility that is being operated, of failures is directly related to the system's level of two basic methods are available for improving availability reliability. when the current level of availability is unacceptable: 70-774 NATIONAL ELECTRICAL CODE 2008 Edition ANNEX F Annex F: Critical Operations Power Systems (1) Selectively adding, redundant units (e.g., generators, (1) Submit Functional Performance Tests (FPTs). chillers, fuel supply to eliminate sources of single-point Systemlcomponent tests or FPTs are developed from sub- failure, and (2) optimizing maintenance using a reliability- mitted drawings, SODS and SOMMs, including large com- centered maintenance (RCM) approach to minimize down- ponent testing (i.e., transformers, cable, generators, UPS), time. [Refer to NFPA 7013-2006, Recommended Practice and how components operate as part of the total system. for Electrical Equipment Maintenance] A combination of The commissioning authority develops the test and cannot the previous two methods can also be implemented.A third be the installation contractor (or subcontractor). very expensive method is to redesign subsystems or to re- As the equipment/components/systems are installed, place components and subsystems with higher reliability quality assurance procedures are administered to verify that items. [Refer to NFPA 70B.] components are installed in accordance with minimum New facilities:The opportunity for high availability and manufacturers' recommendations, safety codes,and accept- reliability is greatest when designing a new facility. By able installation practices. Quality assurance discrepancies applying an effective reliability strategy, designing for are then identified and added to a "commissioning action maintainability, and ensuring that manufacturing and com- list" that must be rectified as past of the commissioning missioning do not negatively affect the inherent levels of program. These items would usually be discussed during reliability and maintainability, a highly available facility commissioning meetings. Discrepancies are usually identi- will result. The approach should be as follows: fied initially by visual inspection. (1) Develop and determine a reliability strategy (establish (2) Review FPTs. The tests must be reviewed by the goals,develop a system model,design for reliability,con- customer, electrical contractors, quality assurance personnel, duct reliability development testing,conduct reliability ac- maintenance personnel, and other key personnel(the commis- ceptance testing, design system delivery, maintain design sioning team). Areas of concern include, among others, all reliability, maintain design reliability in operation). functions of the system being tested, all major components (2) Develop a reliability program. This is the application of included, whether the tests reflect the system operating docu- the reliability strategy to a specific system, process, or ments, and verification that the tests make sense. function. Each step in the preceding strategy requires the (3)Mahe Changes to FPTs as Required.The commis- selection and use of specific methods and tools. For ex- sioning authority then implements the corrections, ques- ample, various tools can be used to develop requirements tions answered, and additions. or evaluate potential failures.To derive requirements,ana- (4) FPTs Approval. After the changes are made to the lyrical models can be used, for example, quality function FPTs,they are submitted to the commissioning team,When development (a technique for deriving more detailed, it is acceptable, the customer or the designated approval lower-level requirements from one level to another,begin- authority approves the FPTs. It should be noted that even ning with mission requirements, i.e., customer needs). though the FPT is approved, problems that arise during the This model was developed as part of the total quality test (or areas not covered) must be addressed. management movement. Parametric models can also be Testing Implementation for FPTs. The final step in used to derive design values of reliability from operational the successful commissioning plan is testing and proper values and vice versa.Analytical methods include but are execution of system-integrated tests. not limited to things such as thermal analysis, durability (1) Systems Ready to Operate. The FPTs can be analysis, and predictions. Finally, one should evaluate implemented as various systems become operative(i.e.,test possible failures. A failure modes and effects criticality for the generator system) or when the entire system is in- analysis (FMECA) and fault tree analysis (FTA) are two stalled. However, the final "pull the plug" test is performed methods for evaluating possible failures. The mission fa- only after all systems are completely installed. If the elec- cility engineer should determine which method to use or trical contractor (or subcontractor) implements the FPTs, a whether to use both, witness must initial each step of the test. The electrical (3) Identify Reliability Requirements. The entire effort for contractor cannot employ the witness directly or indirectly. designing for reliability begins with identifying the (2) Perform Tests (FPTs). If the system fails the test, mission critical facility's reliability requirements. the problem must be resolved and the equipment or system These requirements are stated in a variety of ways, retested or the testing requirements re-analyzed until suc- depending on the customer and the specific system. For cessful tests are witnessed. Once the system or equipment a mission-critical facility, it would be the mission suc- passes testing, it is verified by designated commissioning cess probability. official. II. Development and Implementation of Functional (3) Customer Receives System.After all tests are com- Performance Tests (FPTs) for Critical Operations pleted (including the "pull the plug" test), the system is Power Systems Development of FPT turned over to the customer. 2008 Edition NATIONAL ELECTRICAL CODE 70-775 Annex G: SCADA ANNEX G Annex G Supervisory Control and Data Acquisition (SCADA) This annex is not a part of the requirements of this NFPA ($) Power Supply. The SCADA system power supply document, but is included far informational purposes only. shall comply with (B)(1) through (B)(3): (A) General. Where provided, the general requirements in (1) The power supply shall be provided with a direct- (A)(1) through (A)(1 I)shall apply to SCADA systems.The current station battery system, rated between 24 and SCADA system for the COPS loads shall be separate from 125 volts dc, with a 72-hour capacity. the building management SCADA system. No single point (2) The batteries of the SCADA system shall be separate failure shall be able to disable the SCADA system. from the batteries for other electrical systems. (1) The SCADA system for the COPS loads shall be sepa- (3) The power supply shall be provided with a properly rate from the building management SCADA system. installed surge-protective device (TVSS) at its termi- (2) No single point failure shall be able to disable the nals with a direct low-impedance path to ground. Pro- SCADA system. tected and unprotected circuits shall be physically sepa- (3) The SCADA system shall be permitted to provide rated to prevent coupling. control and monitor electrical and mechanical utility (C) Security Against Hazards. Security against hazards systems related to mission critical loads, including, shall be provided in accordance with (C)(1) through(C)(6): but not limited to the following: a. The fire alarm system (1) Controlled physical access by authorized personnel to b. The security system only the system operational controls and software shall c. Power distribution be provided. d. Power generation (2) The SCADA system shall be protected against dust, e. HVAC and ventilation (damper position, airflow dirt,water,and other contaminants by specifying enclo- speed and direction) sures appropriate for the environment. f. Load shedding (3) Conduit and tubing shall not violate the integrity of the g, Fuel levels or hours of operation SCADA system enclosure. (4) Before installing or employing a SCADA system, an operations and maintenance analysis and risk assess- (4) The SCADA system shall be located in the same secure locations as the secured systems that they monitor and ment shall be performed to provide the maintenance control. parameter data (5) A redundant system shalt be provided in either warm (5) The SCADA system shall be provided with dry agent or hot standby. fire protection systems or double interlocked preaction(6) The controller shall be a programmable logic control- sprinkler systems using cross-zoned detection, to mini- mize the threat of accidental water discharge into un- protected equipment. The fire protection systems shall (7) The SCADA system shall utilize open, not propri- be monitored by the fire alarm system in accordance etary, protocols. with NFPA 720-2007, National Fire Alarm Code. (8) The SCADA system shall be able to assess the dam- (6) The SCADA system shall not be connected to other age and determine system integrity after the "event." network communications outside the secure locations (9) The monitor display shall provide graphical user in- without encryption or use of fiber optics. terface for all major components monitored and con- trolled by the SCADA system, with color schemes (D) Maintenance and Testing. SCADA systems shall be readily recognized by the typical user. maintained and tested in accordance with (13)(1) and (10) The SCADA system shall have the capability to provide (13)(2). storage of critical system parameters at a 15-minute rate or more often when out-of-limit conditions exist. (1) Maintenance. The maintenance program for SCADA (11) The SCADA system shall have a separate data storage systems shall consist of the following components: facility not located in the same vicinity. (1) A documented preventive maintenance program 70-776 NATIONAL ELECTRICAL CODE 2008 Edition ANNEX G Annex G: SCADA (2) Concurrent maintenance capabilities, to allow the test- (2) Testing. SCADA systems shall be tested periodically ing, troubleshooting, repair, and/or replacement of a under actual or simulated contingency conditions, component or subsystem while redundant compo- FPN No. l; Periodic system testing procedures can dupli- nent(s) or subsystem(s) are serving the load cate or be derived from the recommended functional per- (3) Retention of operational data — the deleted material formance testing procedures of individual components, as goes well beyond requirements to ensure proper main- provided by the manufacturers. tenance and operation FPN No.2: For more information on maintenance and test- ing of SCADA, see NFPA 70B-2006, Recommended Prac- tice for Electrical Equipment Maintenance. 2008 Edition NATIONAL ELECTRICAL CODE 70--777 Annex H:Administration ANNEX H Annex H Administration and Enforcement Annex H is not a part of the requirements of this NFPA permitted to be continued in use unless the authority having document and is included for informational purposes only, jurisdiction determines that the lack of conformity with this This annex is informative unless specifically adopted by the Code presents an imminent danger to occupants. Where local jurisdiction adopting the National Electrical Code°. changes are required for correction of hazards, a reasonable amount of time shall be given for compliance, depending 80.1 Scope. The following functions are covered: on the degree of the hazard. (1) The inspection of electrical installations as covered by 90.2 (C) Additions,Alterations, or Repairs. Additions, alter- (2) The investigation of fires caused by electrical installations ations, or repairs to any building, structure, or premises (3) The review of construction plans, drawings, and speci- shall conform to that required of a new building without fications for electrical systems requiring the existing building to comply with all the re- quirements of this Cade. Additions, alterations, installa- (4) The design, alteration, modification,construction,mainte- nance, tions, or repairs shall not cause an existing building to be- and testing of electrical systems and equipment come unsafe or to adversely affect the performance of the (5) The regulation and control of electrical installations at building as determined by the authority having jurisdiction. special events including but not limited to exhibits, Electrical wiring added to an existing service, feeder, or trade shows, amusement parks, and other similar spe- branch circuit shall not result in an installation that violates cial occupancies the provisions of the Code in force at the time the additions 80.2 Definitions. are made. Authority Having Jurisdiction. The organization, of- fice, or individual responsible for approving equipment, 80.11 Occupancy of Building or Structure. materials, an installation, or a procedure. (A) New Construction. No newly constructed building Chief Electrical Inspector.An electrical inspector who shall be occupied in whole or in part in violation of the either is the authority having jurisdiction or is designated provisions of this Code. by the authority having jurisdiction and is responsible for administering the requirements of this Code. (B) Existing Buildings. Existing buildings that are occu- Electrical Inspector. An individual meeting the re- pied at the time of adoption of this Code shall be permitted quirements of 80.27 and authorized to perform electrical to remain in use provided the following conditions apply: inspections. (1) The occupancy classification remains unchanged 80.3 Purpose. The purpose of this article shall be to pro- (2) There exists no condition deemed hazardous to life or vide requirements for administration and enforcement of property that would constitute an imminent danger the National Electrical Code. 80.13 Authority. Where used in this article, the term au- 80.5 Adoption. Article 80 shall not apply unless specifi- thority having jurisdiction shall include the chief electrical tally adopted by the local jurisdiction adopting the Na- inspector or other individuals designated by the governing tional Electrical Code. body.This Code shall be administered and enforced by the authority having jurisdiction designated by the governing 80.7 Title. The title of this Code shall be NFPA 70, Na- authority as follows. tional Electrical Code°, of the National Fire Protection (1) The authority having jurisdiction shall be permitted to Association. The short title of this Code shall be the NEC . render interpretations of this Code in order to provide clarification to its requirements, as permitted by 90.4. 80.9 Application. (2) When the use of any electrical equipment or its instal- (A) New Installations. This Code applies to new installa- lations is found to be dangerous to human life or prop- tions. Buildings with construction permits dated after adop- erty,the authority having jurisdiction shall be empow- tion of this Code shall comply with its requirements. ered to have the premises disconnected from its source of electric supply, as established by the Board. (B) Existing Installations. Existing electrical installations When such equipment or installation has been so con- that do not comply with the provisions of this Code shall be demned or disconnected, a notice shall be placed 70-778 NATIONAL ELECTRICAL CODE 2008 Edition ANNEX H Annex H:Administration thereon listing the causes for the condemnation, the (9) Persons shall not interfere with an authority having disconnection, or both, and the penalty under 80.23 jurisdiction carrying out any duties or functions pre- for the unlawful use thereof. Written notice of such scribed by this Code. condemnation or disconnection and the causes there- (10) Persons shall not use a badge, uniform, or other for shall be given within 24 hours to the owners, the credentials to impersonate the authority having ju- occupant, or both, of such building, structure, or pre- risdiction, mises. It shall be unlawful for any person to remove (11) The authority having jurisdiction shall be permitted to said notice, to reconnect the electrical equipment to its investigate the cause,origin,and circumstances of any source of electric supply, or to use or permit to be fire, explosion, or other hazardous condition. used electric power in any such electrical equipment (12) The authority having jurisdiction shall be permitted to until such causes for the condemnation or disconnec- require plans and specifications to ensure compliance tion have been remedied to the satisfaction of the in- with this Code. spection authorities. (13) Whenever any installation subject to inspection prior (3) The authority having jurisdiction shall be permitted to to use is covered or concealed without having first delegate to other qualified individuals such powers as been inspected, the authority having jurisdiction shall necessary for the proper administration and enforce- be permitted to require that such work he exposed for ment of this Code. inspection. The authority having jurisdiction shall be (4) Police, fire,and other enforcement agencies shall have notified when the installation is ready for inspection authority to render necessary assistance in the en- and shall conduct the inspection within _days. forcement of this Code when requested to do so by the (14) The authority having jurisdiction shall be permitted to authority having jurisdiction. order the immediate evacuation of any occupied (5) The authority having jurisdiction shall be authorized building deemed unsafe when such building has haz- to inspect, at all reasonable times, any building or ardous conditions that present imminent danger to premises for dangerous or hazardous conditions or building occupants. equipment as set forth in this Code. The authority (15) The authority having jurisdiction shall be permitted to having jurisdiction shall be permitted to order any waive specific requirements in this Code or permit person(s)to remove or remedy such dangerous or haz- alternative methods where it is assured that equivalent ardous condition or equipment. Any person(s) failing objectives can be achieved by establishing and main- to comply with such order shall be in violation of this taining effective safety.Technical documentation shall Code. be submitted to the authority having jurisdiction to (6) Where the authority having jurisdiction deems that demonstrate equivalency and that the system, method, conditions hazardous to life and property exist, he or or device is approved for the intended purpose. she shall he permitted to require that such hazardous (16) Each application for a waiver of a specific electrical conditions in violation of this Code be corrected. requirement shall be filed with the authority having jurisdiction and shall be accompanied by such evi- (7) To the full extent permitted by law, any authority hav- ing deuce,letters,statements,results of tests,or other sup- authorized jurisdiction engaged in inspection work shall be porting information as required to justify the request, authorized at all reasonable times to enter and exam- The authority having jurisdiction shall keep a record ine any building, structure, or premises for the pur- of actions on such applications, and a signed copy of pose of making electrical inspections. Before entering the authority having jurisdiction's decision shall be a premises, the authority having jurisdiction shall ob- provided for the applicant. tain the consent of the occupant thereof or obtain a court warrant authorizing entry for the purpose of in- 50.15 Electrical Board. spection except in those instances where an emer- gency exists. As used in this section, enrergenc�, (A) Creation of the Electrical Board. There is hereby created the Electrical Board of the of means circumstances that the authority having juris- hereinafter designated as the Board. diction knows, or has reason to believe, exist and that reasonably can constitute immediate danger to per- (B) Appointments. Board members shall be appointed by sons or property. the Governor with the advice and consent of the Senate (or (8) Persons authorized to enter and inspect buildings, by the Mayor with the advice and consent of the Council, structures, and premises as herein set forth shall be or the equivalent). identified by proper credentials issued by this govern- (1) Members of the Board shall be chosen in a manner to ing authority. reflect a balanced representation of individuals or 2008 Edition NATIONAL ELECTRICAL CODE 70-779 Annex H:Administration ANNEX H organizations.The Chair of the Board shall be elected by ness. The Board shall hold such meetings as necessary to the Board membership. carry out the purposes of Article 80. The Chair or a major- (2) The Chief Electrical Inspector in the jurisdiction adopt- ity of the members of the Board shall have the authority to ing this Article authorized in (B)(3)(a)shall be the non- call meetings of the Board. voting secretary of the Board. Where the Chief Electri- cal Inspector of a local municipality serves a Board at a (F) Duties. It shall be the duty of the Board to perform the state level, he or she shall be permitted to serve as a following: voting member of the Board. (1) Adopt the necessary rules and regulations to administer (3) The board shall consist of not fewer than five voting and enforce Article 80. members. Board members shall be selected from the (2) Establish qualifications of electrical inspectors. following: (3) Revoke or suspend the recognition of any inspector's a. Chief Electrical Inspector from a local government certificate for the jurisdiction. (for State Board only) (4) After advance notice of the public hearings and the b. An electrical contractor operating in the jurisdiction execution of such hearings, as established by law, the c. A licensed professional engineer engaged primarily in Board is authorized to establish and update the provi- the design or maintenance of electrical installations sions for the safety of electrical installations to conform d. A journeyman electrician to the current edition of the National Electrical Code (4) Additional membership shall be selected from the (NFPA 70) and other nationally recognized safety stan- following: dards for electrical installations. a. A master (supervising) electrician (5) Establish procedures for recognition of electrical safety b. The Fire Marshal (or Fire Chief) standards and acceptance of equipment conforming to c. A representative of the property/casualty insurance these standards, industry d. A representative of an electric power utility operat- (G) Appeals. ing in the jurisdiction e. A representative of electrical manufacturers prima- (1) Review of Decisions. Any person, firm, or corporation may register an appeal with the Board for a review of rily and actively engaged in producing materials, any decision of the Chief Electrical Inspector or of any fittings, devices, appliances, luminaires, or appara- Electrical Inspector, provided that such appeal is made tus used as part of or in connection with electrical in writing within fifteen (15) days after such person, installations firm, or corporation shall have been notified. Upon re- f. A member of the labor organization that represents ceipt of such appeal, said Board shall, if requested by the primary electrical workforce the person making the appeal, hold a public hearing g. A member from the public who is not affiliated with and proceed to determine whether the action of the any other designated group Board, or of the Chief Electrical Inspector, or of the h. A representative of a telecommunications utility op- Electrical Inspector complies with this law and, within erating in the jurisdiction fifteen (15) days after receipt of the appeal or after (C) Terms. Of the members first appointed, shall holding the hearing, shall make a decision in accor- be appointed for a term of I year, for a term of 2 dance with its findings. years, for a term of 3 years, and for a term of (2) Conditions. Any person shall be permitted to appeal a 4 years, and thereafter each appointment shall be for a term decision of the authority having jurisdiction to the of 4 years or until a successor is appointed. The Chair of Board when it is claimed that any one or more of the the Board shall be appointed for a term not to exceed following conditions exist: years. a. The true intent of the codes or ordinances described in this Code has been incorrectly interpreted. (D) Compensation. Each appointed member shall receive b. The provisions of the codes or ordinances do not the sum of dollars ($ ) for each day during fully apply. which the member attends a meeting of the Board and, in c. A decision is unreasonable or arbitrary as it applies addition thereto, shall be reimbursed for direct lodging, to alternatives or new materials. travel, and meal expenses as covered by policies and pro- (3) Submission of Appeals. A written appeal, outlining the cedures established by the jurisdiction. Code provision from which relief is sought and the remedy proposed, shall be submitted to the authority (E) Quorum. A quorum as established by the Board op- having jurisdiction within 15 calendar days of notifica- erating procedures shall be required to conduct Board busi- tion of violation. 70-780 NATIONAL ELECTRICAL CODE 2008 Edition ANNEX H Annex H:Administration (H) Meetings and Records. Meetings and records of the (4) Permit number and date of issuance Board shall conform to the following: (5) Period of validity of the permit (1) Meetings of the Board shall be open to the public as (6) Inspection requirements required by law. (2) Records of meetings of the Board shall be available for (C) Issuance of Permits. The authority having jurisdic- review during normal business hours, as required by tion shall be authorized to establish and issue permits, cer- laa tificates, notices, and approvals, or orders pertaining to electrical safety hazards pursuant to 80.23, except that no 80.17 Records and Reports. The authority having juris- permit shall be required to execute any of the classes of diction shall retain records in accordance with (A) and (B). electrical work specified in the following: (1) Installation or replacement of equipment such as lamps (A) Retention. The authority having jurisdiction shall and of electric utilization equipment approved for con- keep a record of all electrical inspections, including the nection to suitable permanently installed receptacles. date of such inspections and a summary of any violations Replacement of Hush or snap switches, fuses, lamp found to exist, the date of the services of notices, and a sockets, and receptacles, and other minor maintenance record of the final disposition of all violations.All required and repair work, such as replacing worn cords and records shall be maintained until their usefulness has been tightening connections on a wiring device served or as otherwise required by law. (2) The process of manufacturing, testing, servicing, or re- (B) Availability. A record of examinations, approvals, and pairing electrical equipment or apparatus variances granted shall be maintained by the authority hav- ing jurisdiction and shall be available for public review as (D) Annual Permits. In lieu of an individual permit for each installation or alteration, an annual permit shall, upon prescribed by law during normal business hours. application, be issued to any person, firm, or corporation regularly employing one or more employees for the instal- 80.19 Permits and Approvals. Permits and approvals lation, alteration, and maintenance of electrical equipment shall conform to (A) through (H). in or on buildings or premises owned or occupied by the (A) Application. applicant for the permit. Upon application, an electrical contractor as agent for the owner or tenant shall be issued (1) Activity authorized by a permit issued under this Code an annual permit. The applicant shall keep records of all shall be conducted by the permittee or the permittee's work done, and such records shall be transmitted periodi- agents or employees in compliance with all require- cally to the Electrical Inspector. ments of this Code applicable thereto and in accor- dance with the approved plans and specifications. No (E) Pees. Any political subdivision that has been provided permit issued under this Code shall be interpreted to for electrical inspection in accordance with the provisions justify a violation of any provision of this Code or any of Article 80 may establish fees that shall be paid by the other applicable law or regulation. Any addition or al- applicant for a permit before the permit is issued. teration of approved plans or specifications shall be approved in advance by the authority having jurisdic- (F) Inspection and Approvals. tion, as evidenced by the issuance of a new or amended (1) Upon the completion of any installation of electrical permit. equipment that has been made under a permit other (2) A copy of the permit shall be posted or otherwise than an annual permit, it shall be the duty of the person, readily accessible at each work site or carried by the firm, or corporation making the installation to notify permit holder as specified by the authority having the Electrical Inspector having jurisdiction, who shall jurisdiction. inspect the work within a reasonable time. (B) Content. Permits shall be issued by the authority hav- (2) Where the Inspector finds the installation to be in con- ing jurisdiction and shall bear the name and signature of the formity with the statutes of all applicable local ordi- authority having jurisdiction or that of the authority having nances and all rules and regulations, the Inspector shall jurisdiction's designated representative. In addition, the issue to the person, firm, or corporation making the permit shall indicate the following: installation a certificate of approval, with duplicate copy for delivery to the owner, authorizing the connec- (1) Operation or activities for which the permit is issued tion to the supply of electricity and shall send written (2) Address or location where the operation or activity is to notice of such authorization to the supplier of electric be conducted service. When a certificate of temporary approval is (3) Name and address of the permittee issued authorizing the connection of an installation, 2008 Edition NATIONAL ELECTRICAL CODE 70-781 Annex H: Administration ANNEX H such certificates shall be issued to expire at a time to be (3) Revocation shall be constituted when the permittee is stated therein and shall be revocable by the Electrical duly notified by the authority having jurisdiction. Inspector for cause. (4) Any person who engages in any business, operation, or (3) When any portion of the electrical installation within occupation, or uses any premises, after the permit is- the jurisdiction of an Electrical Inspector is to be hid- sued therefor has been suspended or revoked pursuant den from view by the permanent placement of parts of to the provisions of this Code, and before such sus- the building, the person, firm, or corporation installing pended permit has been reinstated or a new permit is- the equipment shall notify the Electrical Inspector, and sued, shall be in violation of this Code. such equipment shall not be concealed until it has been (5) A permit shall be predicated upon compliance with the approved by the Electrical Inspector or until requirements of this Code and shall constitute written days have elapsed from the time of such notification, authority issued by the authority having jurisdiction to provided that on large installations, where the conceal- install electrical equipment. Any permit issued under ment of equipment proceeds continuously, the person, this Code shall not take the place of any other license firm, or corporation installing the equipment shall give or permit required by other regulations or laws of this the Electrical Inspector due notice in advance, and in- jurisdiction. spections shall be made periodically during the (6) The authority having jurisdiction shall be permitted to progress of the work. require an inspection prior to the issuance of a permit. (4) At regular intervals, the Electrical Inspector having ju- (7) A permit issued under this Code shall continue until risdiction shall visit all buildings and premises where revoked or for the period of time designated on the per- work may be done under annual permits and shall in- mit.The permit shall be issued to one spect all electrical equipment installed under such per- person or business only and for the location or purpose described in the per- mits since the date of the previous inspection, The mit.Any change that affects any of the conditions of the Electrical Inspector shall issue a certificate of approval permit shall require a new or amended permit, for such work as is found to be in conformity with the provisions of Article 80 and all applicable ordinances, (H) Applications and Extensions. Applications and ex- orders, rules, and regulations, after payments of all re- tensions of permits shall conform to the following: quired fees. (1) The authority having jurisdiction shall be permitted to (5) If, upon inspection, any installation is found not to be grant an extension of the permit time period upon pre- fully in conformity with the provisions of Article 80, sentation by the permittee of a satisfactory reason for and all applicable ordinances, rules, and regulations, failure to start or complete the work or activity autho- the Inspector making the inspection shall at once for- rixed by the permit. ward to the person, firm, or corporation making the (2) Applications for permits shall be made to the authority installation a written notice stating the defects that have having jurisdiction on forms provided by the jurisdic- been found to exist. tion and shall include the applicant's answers in full to (G) Revocation of Permits. Revocation of permits shall inquiries set forth on such forms. Applications for per- conform to the following: mits shall be accompanied by such data as required by (1) The authority having jurisdiction shall be permitted to the authority having jurisdiction, such as plans and revoke apermit or approval issued if any violation of specifications, location, and so forth. Fees shall be de- this Code is found upon inspection or in case there termined as required by local laws. have been any false statements or misrepresentations (3) The authority having jurisdiction shall review all appli- submitted in the application or plans on which the per- cations submitted and issue permits as required. If an mit or approval was based. application for a permit is rejected by the authority (2) Any attempt to defraud or otherwise deliberately or having jurisdiction, the applicant shall be advised of the reasons for such rejection. Permits for activities knowingly design, install, service, maintain, operate, requiring evidence of financial responsibility by the ju- sell, represent for sale, falsify records, reports, or ap- risdiction shall not be issued unless proof of required plications, or other related activity in violation of the financial responsibility is famished. requirements prescribed by this Code shall be a viola- tion of this Code. Such violations shall be cause for 80.21 plans Review. Review of plans and specifications immediate suspension or revocation of any related li- shall conform to (A) through (C}. censes, certificates, or permits issued by this jurisdic- tion. In addition, any such violation shall be subject to (A) Authority. For new construction, modification, or re- any other criminal or civil penalties as available by the habilitation, the authority having jurisdiction shall be per- laws of this jurisdiction. mitted to review construction documents and drawings. 70-782 NATIONAL ELECTRICAL CODF 2008 Edition ANNEX H Annex H:Administration (B) Responsibility of the Applicant. It shall be the re- (3) Any person, firm, or corporation who shall willfully sponsibility of the applicant to ensure the following: violate any of the applicable provisions of this article (1) The construction documents include all of the electrical shall be guilty of a misdemeanor and, upon conviction requirements. thereof, shall be punished by a fine of not less than (2) The construction documents and drawings are correct dollars ($ ) or more than dollars and in compliance with the applicable codes and ( ) for each offense, together with the costs of standards. prosecution, imprisonment, or both, for not less than (C) Responsibility of the Authority Having Jurisdiction, days.( ) days or more than ( } It shall be the responsibility of the authority having juris- diction to promulgate rules that cover the following: 80.25 Connection to Electricity Supply. Connections to (1) Review of construction documents and drawings shall the electric supply shall conform to (A) through (E). be completed within established time frames for the purpose of acceptance or to provide reasons for nonac- (A) Authorization. Except where work is done under an ceptance. annual permit and except as otherwise provided in 80.25, it (2) Review and approval by the authority having jurisdic- shall be unlawful for any person, firm, or corporation to tion shall not relieve the applicant of the responsibility make connection to a supply of electricity or to supply of compliance with this Code. electricity to any electrical equipment installation for which (3) Where field conditions necessitate any substantial a permit is required or that has been disconnected or or- change from the approved plan, the authority having dered to be disconnected. jurisdiction shall be permitted to require that the cor- rected plans be submitted for approval. (B) Special Consideration. By special permission of the authority having jurisdiction, temporary power shall be per- 80.23 Notice of Violations, Penalties. Notice of viola- mitted to be supplied to the premises for specific needs of tions and penalties shall conform to (A) and (B). the construction project. The Board shalt determine what needs are permitted under this provision. (A) Violations. (1) Whenever the authority having jurisdiction determines (C) Notification. If, within business days after the that there are violations of this Code, a written notice Electrical Inspector is notified of the completion of an in- shall be issued to confirm such findings. stallation of electric equipment, other than a temporary ap- (2) Any order or notice issued pursuant to this Code shall proval installation, the Electrical Inspector has neither cu- be served upon the owner, operator, occupant, or other thorized connection nor disapproved the installation, the person responsible for the condition or violation, either supplier of electricity is authorized to make connections by personal service or mail or by delivering the same and supply electricity to such installation. to, and leaving it with, some person of responsibility upon the premises. For unattended or abandoned loca- (D) Other Territories. If an installation or electric equip- tions, a copy of such order or notice shall be posted on ment is located in any territory where an Electrical Inspec- the premises in a conspicuous place at or near the en- for has not been authorized or is not required to make trance to such premises and the order or notice shall be inspections, the supplier of electricity is authorized to make mailed by registered or certified mail, with return re- connections and supply electricity to such installations. ceipt requested, to the last known address of the owner, occupant, or both. (E) Disconnection. Where a connection is made to an in- stallation that has not been inspected, as outlined in the (B) Penalties. preceding paragraphs of this section, the supplier of elec- (1) Any person who fails to comply with the provisions of tricity shall immediately report such connection to the this Code or who fails to carry out an order made pur- Chief Electrical Inspector. If,upon subsequent inspection,it suant to this Code or violates any condition attached to is found that the installation is not in conformity with the a permit, approval, or certificate shall be subject to the provisions of Article 80, the Chief Electrical Inspector shall penalties established by this jurisdiction. notify the person, firm, or corporation making the installa- (2) Failure to comply with the time limits of an abatement tion to rectify the defects and, if such work is not com- notice or other corrective notice issued by the authority pleted within fifteen (15) business days or a longer period having jurisdiction shall result in each day that such as may be specified by the Board, the Board shall have the violation continues being regarded as a new and sepa- authority to cause the disconnection of that portion of the rate offense. installation that is not in conformity. 2008 Edition NATIONAL ELECTRICAL.CODE 70-783 Annex H:Administration ANNEX H 80.27 Inspector's Qualifications. ation and shall have had two years' practical electrical (A) Certificate. All electrical inspectors shall be certified experience. by a nationally recognized inspector certification program (C) Recertification. Electrical inspectors shall be recerti- accepted by the Board. The certification program shall spe- fied as established by provisions of the applicable certifica- cifically qualify the inspector in electrical inspections. No tion program. person shall be employed as an Electrical Inspector unless that person is the holder of an Electrical Inspector's certifi- (D) Revocation and Suspension of Authority. The Board cate of qualification issued by the Board, except that any shall have the authority to revoke an inspector's authority person who on the date on which this law went into effect to conduct inspections within a jurisdiction. was serving as a legally appointed Electrical inspector of shall, upon application and payment of the pre- 80.29 Liability for Damages. Article 80 shall not be con- scribed fee and without examination, be issued a special strued to affect the responsibility or liability of any party certificate permitting him or her to continue to serve as an owning, designing, operating, controlling, or installing any Electrical Inspector in the same territory. electrical equipment for damages to persons or property (B) Experience. Electrical inspector applicants shall dem- caused by a defect therein, nor shall the or any of its employees be held as assuming any such liability by onstrate the following: reason of the inspection, reinspection, or other examination (1) Have a demonstrated knowledge of the standard mate- authorized. rials and methods used in the installation of electric equipment 80.31 Validity. If any section, subsection, sentence, (2) Be well versed in the approved methods of construction clause, or phrase of Article 80 is for any reason held to be for safety to persons and property unconstitutional, such decision shall not affect the validity (3) Be well versed in the statutes of relating to of the remaining portions of Article 80. electrical work and the National Electrical Code, as approved by the American National Standards Institute 80.33 Repeal of Conflicting Acts. All acts or parts of acts (4) Have had at least years' experience as an Electri- in conflict with the provisions of Article 80 are hereby cal Inspector or years in the installation of elec- repealed. trical equipment. In lieu of such experience, the appli- cant shall be a graduate in electrical engineering or of a 80.35 Effective Date. Article 80 shall take effect similar curriculum of a college or university considered ( )days after its passage and pub- by the Board as having suitable requirements for gradu- lication. 70-784 NATIONAL ELECTRICAL CODE 2008 Edition INDEX Alarms Index G 2007 National Fire Protection Association.All Rights Reserved. The copyright in this index is separate and distinct from the copyright in the document that it indexes.The licensing provisions set forth for the document are not applicable to this index.This index may not be reproduced in whole or in part by any means without the express written permission of NFPA. -A- AC resistance and reactance Luminaires,547.8 Hermetic refrigerant motor- AC and DC conductors in same conversion,Chap.9, Motors,547.7 compressor,see Her- enclosure,300.3(C)(1), Table 9 Service equipment, separately metic refrigerant motor- 725.48 AC systems derived systems, feed- compressors AC armored cable,see Armored Conductor to be grounded, ers,disconnecting Leakage-current detector- cable(Type AC) 250.26 means,and grounding, interrupter,440.65 Access and working space,see Grounding connections, 547.9 Definition,410.2 also Working space 250.24(A) Surface temperatures,547.4 Load, 220.82(C).220.83 Audio signal processing,ampli- Grounding electrode conductor, Switches,receptacles,circuit Mobile homes,550.20 fication,and reproduc- 250.66 breakers,controllers, Nameplate requirements,440.4 lion equipment,640.46 Grounding of,250.20,250.30 and fuses,547.6 Overload protection,44(-VI Elevator machine room, 620.71 Systems not required to be Wiring methods,547,5 Application and selection of, Induction and dielectric heating grounded.250.21 Air conditioners,room,440-VII 440.52 equipment,665.22 In same metallic enclosures, Branch-circuit conductors for, Manholes, 110.72, 110.73, 215.4(B),300.20 Branch-circuit requirements, 440.62 440,52(B) 110,75 Sensitive electronic equipment. General,410,51 Not over 600 volts, I IU.26 647.3,647.5 Definition,Disconnecting me Over 600 volts, 110-11I Administration and enforcement, Grounding,n ding,ng means,440.63 Motor-compressors. Portable substations, 530.62 Annex H Grounding,4arkin 445-or 2) Switchboards,408.18 Adoption of Cade, Annex H Nameplate marking 220.82(C1. On ran h ircumpere Transformers.electric signs, 80.5 440.4 branch circuits, 430.54 b Park trailers,552.59(B) 600.21(D) Application of Code. Annex H Air-conditioning and refrigerat- Vaults and tunnels, l 10.76 80.9 ing equipment,Art. Rated-load current Accessible Authority,Annex H 80.13 410 Definition,440.2 Air-conditioning and refrigera- Connection to electricity supply, Are-fault circuit-interrupter pro- Marking on nameplate, flan disconnects.440.14 Annex H 80,25 tection,440.65 440.4(A) Room air conditioners,see Air Conduit bodies,junction,pull, Definitions,Annex H 80.2 Branch circuit and outlet boxes, 314.29 Effective date, Annex H 80.35 Conductors,440-IV Si conditioners, con sid- Definition,Art. 100-1 Electrical board,Annex H 80.15 Ampacity,determination Single machine,when con Grounding electrode connection, Inspector's qualifications,Annex of,440.6 rand,'Trucks transporting rung refrigerated 250.68(A) H 80.27 Combination loads for. Motor disconnects,430.107 Liability for damages.Annex H 440,34 units,see Electrified Overcurrent devices,240.24 80.29 General.440.31 truck parking space equipment Panels,and cables,raceways, Notice of violations,penalties, Multimotor equipment fir. Aircraft hangars,Art.S l3 busways,and equipment Annex H 80.23 940.35 installed behind, Occupancy of building or struc- Several motor-compressors Aircraft electrical system 36N.10(B),725.21, ture,Annex H 80.11 for 440.33 Aircraft electrical systems, 760.21,770.21.800.21, Permits and approvals,Annex H Single motor-compressor 513.10(A) 830.221 80.19 for,440.32 Classificatioon n ooff locations,513.3 Definitions,513.2 Readily Plans review,Annex H 80.21 Outlets,210.63 51 Equipment. 3.4,513.7,513.8, Definition,Art. 100-1 Records and reports,Annex H selection current 513.10 t.51 Sealing fittings,501.15(C)(1), 80.17 Definition.440.2 502.15,505.16(D)(1), Repeal of conflicting acts,An- Ground-fault circuit interrupters, Marking on nameplate, 513.12 506.16;see also Haz- nex H 80.33 440.4(C) ardour(classified)loca- Title of Code, Annex H 80.7 Grounding and bonding,513.16 tions Validity of article,Annex H short-circuit and ground-Vault Mobile servicing equipment, Services,230.70 80,31 protection, .440.I 513.7(F),513.10(D) Splices and taps in auxiliary Aerial cables Equipment for,440.22(B) Painting hangar,513.3(C)(2) gutters,366.56(A) Identification,200.6(A) General, l mot Definition,513.2 Individual motor- Portable equipment,513.1U(EI Splices and taps in wireways, Installation,820.44 376.56. 378.56 Messenger-supported wiring, compressor for, Sealing,513,9 Transformers, signs,outlet light- Art.396 440.22(A) Stanchions,rostrums,and docks, ing,600.21(A) Network-powered broadband Controllers for,440-V 513.7(E) Transformers and vaults,450.13 communications systems Marking,440.5 Wiring,513.4,513.7,513.8 Unfinished attics and roof -aerial cables,830.44 Rating,440.41 Air ducts,see Ducts spaces,knob-and-tube Agricultural buildings,Art.547 Definitions,440 2,551.2 Air plenums,see Plenums wiring,394.23(A) Bonding and equipotential Disconnecting means,440 II Air terminals,see Lightning AC-DC general-use snap plane,547.10 Cord-connected equipment, rods; Lightning(surge) switches Definitions,547.2 440.13 arresters Marking.404,15 Equipotential planes,bonding, Ratings and interrupting ca- Alarms Motors,430.83(C) 547.10 pacity,440.12 Burglar,see Remote-control, Panelboards,use in.408.36(A) Feeder and service loads,calcu- Room air conditioners, signaling,und power- Ratings,type loads,408.36(A) lation of, 220-V 440.63 limited circuits 2008 Edition NATIONAL ELECTRICAL CODE 70-785 Alarms INDEX Fire,230.82(51,230.94 Ex.4. Definition,504.2 Arc-welder motors,see Welders, Nonmetallic-sheathed cable, see also Fire alarm Intrinsically safe,grounding of, electric 334.23 systems 504.50(A) Arc welders,see Welders,electric Open wiring,398.23 Alarm systems,health care Facili- Definition,504.2 Arenas,410.10(E),Art.518,Art. Sign transformers in,600.21(E) ties,517.32(C), Simple 520 Audio signal processing,amplifi- 517.42(C) Definition,5042 Emergency lighting system, Art, cation,and reproduc- Alternate power source,see Appliances,Art.422;see also 700 tion equipment,Art. Power source,alter- Motors Armored cable(Type AC),Art. 640 nate Battery-powered,517.64(E) 320 Access,640.5,640.46 Definition,517.2 Branch circuits,see Branch cir- Accessible attics,320.23 Conduit or tubing,640.23 Alternators,.tee Generators cuits,appliances Ainpacity. 320.80 Definitions,640.2 Aluminum conduit,see Rigid Cords,see Cords,flexible Bends,320.24 Environmental protection, metal conduit Definition,Art. 1004 Boxes and fittings,320.40 640.44 Aluminum siding,grounding of, Disconnecting means,422-III Conductor type,320.104 Flexible cords,use of,640.21, 250.116 FPN Dwelling units,outlets,210.52 Construction,320.100,320-III 640.42,640.45 Ambient temperature,3 10.10 Feeder calculations for, 220,40 Definition,320.2 Grounding,640.7 FPN;see also Tempera- Fixed,550.12(D),551.42(A)to Equipment grounding, 320.108 Grouping of conductors,640.8 ture limitations (C) Equipment grounding conductor Locations and other articles, Ambulatory health care centers, Definition,550.2,551.2 installation,250.120(A) 640.3 see also Health care Grounding,250-V1,550,16, Exposed work,320.15 Loudspeakers in fire-resistant facilities 551.54 Marking,320.120 construction,640.25 Definition,517.2 Hazardous(classified) locations, Supports,320.30 Mechanical execution of work, Essential electrical systems, see Hazardous(classi- Through or parallel to framing 640.6 517,45 fled)locations members,320.17 Motion picture projectors, Ampacities,see also subhead, Household cooking,demand Uses not permitted,320.12 540.50 Ampacities,under err- factors and loads for, Uses permitted,320.10 Permanent installations,640-11 tries for specific wiring Table 220.55 Armories,Art,518 Portable and temporary installa- and equipment Installation,422--II Emergency lighting system, Art, tions,640-III Conductors,310.15,Tables Load calculations,220.14, 700 Protection of electrical equip- 310.16 through 310.2 1, 220,40,Table 220.55 Array,solar photovoltaic systems ment,640.4 310.67 through 310.86, Marking,422--V Definition,690.2 Theaters,520.4 366.23, B.310.1 through Mobile homes,in,550.12(B) Arresters,surge,see Lightning Transformers,640.9(D) B.310.10 and(D),550.14 (surge)arresters Definition, 640.2 Amusement attractions, Motor-driven,422.10(A) Artificially made bodies of water, Underwater,680,27(A), 522.22 Disconnecting means,422.32 see Natural and artifi- 680.43(G) Crane and hoist,Table Load, 220.18(A) ciaily made bodies of Water,near, 640.10 610.14(A) water,electrical wiring Wireways,gutters,auxiliary gut- Marking,422.62 Motors, motor circuits,and Overload protection, and equipment for tens, 640.24 p , controllers,430.6 Askarels Wiring methods,640.9 11(G} Definition,Art. 100-I 422. Definition,Art. 100-I Wiring of equipment racks, Fixture wires,402.5 Overcurrent protection,422.11 Transformers,450.25 640,22,640.43 E Single, 210.20,422.11( ) Grounding,250.122 Portable Assembly,places of,410.10(E), Auditoriums,Art.518,Art.520 Tables,0-2000 volts,310.16 Art. 518 Emergency lighting system,Art. through 310.21,Annex Definition,550.2,551.2 Classifications,518.2 700 B Recreational vehicles,in, Emer g enc y li g htin g s y stem, Art. Authori ty havin g jurisdiction, 551. 1 41C Ex. , 42 Amusement attractions,control 551. 700 90.4;see also Approval, systems for permanent, Signal transmission between, Supply,518,5 approved Art.522 517.82 Theaters,audience areas,Art. Definition,Art. 100-I Small,210.52(B),550.12(B) Control circuits,522-L[ 520 Automatic Control circuit wiring methods, Stationary Wiring methods,518.4 Definition,Art. 100-1 Definition,550.2,551.2 522-III Atmospheric groups,see Hazard- Aul❑transiormers,see Transform- Definitions,522.2 Subject to immersion,422.41 ous(classified)locations ers Maintenance,522.7 Terminals,identification of, Attachment plugs(caps),see also Auxiliary gutters,Art.366 Voltage limitations,522.5 200.10(E) Hazardous(classified) Conductors Anesthetizing locations,517-IV; Approval,approved locations;Receptacles, Ampacities,366.23 see also Health care Definition,Art. 100-I cord connectors and Clearance,bare live parts, facilities Equipment and materials,90.4, attachment plugs(caps) 366.100(6) Definition,517.2 90.7, 110.2,500.8(8), Construction of,406.6 Insulated,366.58 Flammable, Annex H 80.19 Definition,Art. 100-1 Number of,366.22 Definition,517.2 Arc-fault circuit interrupters, Flexible cords on,210.50(B), Construction specifications, Antenna discharge units,810.20, 210.12 400.7(B),400.24 366-III 810.57 Definition,210.12(A) Grounding type,406.9 Covers,366.100(D) Antenna systems,radio and tele- Protection, 210.12(B),440.65, Polarized,terminal identifica- Definitions,366.2 vision,see Community 550.25 tion,200.10(B) Extension beyond equipment, antenna television and Arcing parts,240.41 Attics 366.12 radio distribution Enclosure of, 110.18,430.14(B), Armored cable,320.23 Grounding,366.60 (CATV)systems; Radio 511.7(B)(1),513.7(C), Knob and tube,394.23 Indoors and television equip- 515.7(B),516.7(B), Lighting outlets required, Listing, 366.6(B) ment 517.61(B)(2) 210.70(A)(3) Marking,366.120(B) Apparatus Are lamps,portable Metal-clad cable,330.23 Uses permitted,366.10(A)(1), Associated,grounding of, Motion picture studios,530.17 Nonmetallic extensions, 366.10(B)(2) 504.50(B) Stage equipment,520.61 382.12(1) Installation,366-II 70-786 NATIONAL ELECMICAL CODE 2008 Edition INDEX Branch circuits Listing.366.6 Lighting outlets required, Flexible metal conduit(Type Construction specifications, Marking,366.120 210.70(A)(1).210.70(B) FMC),348.60 314-II1 Metallic Overcurrent devices,240.24(E) Floating buildings,553.11 Covers,314.25,314.28(C), Conductors,366.22(A), Receptacles in,210.8(A)(1), Garages,commercial,511.16 314.41.314.42, 366.23(A) 210.8(8)(1),210.52(D), Grounding-type receptacles, 314.72(E) Definition. 366.2 406.8(C),550.12(E), 250.146 Cutout,see Cabinets,cutout Securing and supporting, 550.13(D),550-13(F), Hazardous(classified)locations, boxes,and meter socket 366.30(A) 551.41(C),552.4](F) see Hazardous(classi- enclosures Uses permitted,366.10(A) Bathtubs fied)locations Damp locations,314.15 Nonmetallic Hydromassage,680-VI, induction and dielectric heating Depth,minimum,314.24 Conductors,366.22(B). 680-VII equipment,665.26 Drop(theaters,etc.).520.40 366.23(B) Definition,680.2 Intersystem bonding termination Definition.366.2 Fixed electric space-heating Definition,Art. 100-1 Definition,520.2 Enclosures. Marking,366.120 equipment cables, lnOnsically safe systems, ures,handhnle,314.29, Securing and supporting, 424.44(G) 504.60 3 366.30(B) Luminaires,410.10(D), Irrigation machines,675.14 Fill calculations,3[4.16(B) Uses permitted,366.10(B) 550,14(D),551.53(B) Liquidtight flexible metal con- Floor, for receptacles,314.271C) Outdoors Batteries,see also Storage duit(Type LFMC), Grounding,250.148,25U-VI Listing,366.6(A) batteries 350.60 Gutters,auxiliary,used as, Marking,366.120(A) Aircraft,113.10 Liquidtight flexible nonmetallic 366,58(B) Uses permitted,366.10(A)(I). Installations,Art.480,690.4, conduit(Type LFNC), Insulating,see Boxes, 366.10(B)(1) 690.71 356.60 nonmetallic Sound recording, similar equip- Nominal voltage Loosely jointed raceways. Junction, pull,see Junction ment,640.7(A),64024 Definition,480.2 250.98 boxes Splices and taps,366.56 Sealed Manufactured buildings,545.11 Lighting(luminaires)outlets, Supports,366.30 Definition,480.2 Motor fuel dispensing facilities, see Lighting outlets Uses not permitted, 366.12 Insulation,480,6(D) 514.16 Metal Uses permitted,366,10 Vents,480.10(B) Naturally and artificially made Construction,314.40,314-III Battery charging equipment, bodies of water,electfi- Grounding,314.4 511.10(A) cal equipment for, 682- Installation,314-II Aircraft hangars,513.10(B) III Nonmetallic,314.3,314.17(C), -B- Bedrooms Network-powered broadband 314.43,334.40 Back-red devices,408.36(D) Arc-fault circuit-interrupter pro- communications sys- Backfill,300.5(F), 300.5(](D) tection,210.12(8), terns,830.100(D). Wireways used as pull boxes, 378.23[8} Ballasts, electric discharge lamps, 550.25(B) 830.106(B) 410-X11I,410-XIV Bell circuits,see Remote-control, Other enclosures,250.96 Not required,590.4(G) Protection in fluorescent fix- signaling,and power- Outside raceway, 250.102(E) Over 600 volts,314.IV tures,410.130(E) limited circuits Over 250 volts,250.97 Plugging(motion picture and Protection in recessed HID fix- Bends,300.34;see also subhead Panelboards 108,40,517,14 TV studios) tures,410,130(F) under entries for spe- Park trailers,552.57 Definition,530.2 Bare conductors cific wiring system Piping systems and exposed Portable,in theaters,520.62 Ampacities,310.15(B)(3) Block(city,town,or village) structural steel,250.104 Repairing plaster around,314?1 Contact conductors,cranes and Definition, 800.2, 830.2 Raceways,see Raceways Required location,300.15 hoists,610-I11 Blocking diode,solar photovol- Receptacles,250.146 Round, 314,2 Definition,Art. 100-1 taic systems Recreational vehicles, Secured supports,300.1 I. Lighting systems operating at 30 Definition,690.2 551.55(B),551.56 314.23 volts or less,411.5(C) Boathouses and boat hoists, Separately derived systems, Snap switches over 300 volts, Service entrance,Types SE, ground-fault circuit 250.104(D) not ganged.404.8(B) USE.338.100 interrupters, Service equipment,250.92, Support of,392.60) Sizing conduits for,Chap.9, 210.8(A)(8), 210.8(0) 250.94 Surface extensions,314.22 Note 3 to Table 1 Boatyards,see Marinas and boat- Signs and outline lighting, Unused openings,closed, Underground conduits,grounded yards 600.7(B) 110.12(A) neutral,230.30 Ex., Bodies,conduit,see Conduit Swimming pools,see Swimming Vertical raceway runs,300.19 230.41 Ex. bodies pools Volume calculations,314.16(A) Barriers,408.3(A)(2) Boilers Tunnels, 110.54 Wall or ceiling,314.20 Basements(cellars) Electrode-type Bonding jumpers,see Jumpers. Wet locations,314.15 Armored cable,320.15 600 volts or less,424-VIII bonding Branch circuits,ArL 210,Art.220 Lighting outlets required. Over 600 volts,490-V Bored holes through studs,joists, Air conditioners,440AV, 210.70(A)(3) Resistance-type,424-VII 300.4(A)(1) 440-VII Nonmetallic etensions, Bonding,250-V Bowling alleys,Art.518 Appliances,210.23,422-11 382.120) Aircraft hangars,513.16 Emergency lighting system,Art. Nonmetallic sheathed cable. Bulk storage plants,515.16 700 Calculations,220-11 334.15 Carnivals,circuses,fairs,and Boxes(outlet,device,pull,and Definition,Art. 100-I Receptacles in,210.8(A)(5). similar events,525-IV junction),Art.314.see Arc-fault circuit-interrupter pro- 210.52(G),406.8(A) CATV and radio distribution also Hazardous(classi- tection,210.12 Unfinished,210.8(A)(5) systems,820.100(D), fled)locations Audio equipment,640.10(A), Bathrooms 820.106 Accessibility,314.29 640.41,640.42(E) Branch circuits for,210.11(C)(3► Communications circuits, Concealed work,314.20 Bathrooms,210.11(C)(3) Definition,Art. 100-1 800.100(D),800.106(B) Conductors, number in box, Busways as branch circuits. Fixed electric space-heating Definition,Art. 100-1 314.16 368.17 equipment cables. Equipotential,547.10,680.26, Entering boxes,conduit hod- Calculation of loads.220-II, 424.44(G) 68233 ies or fittings,314.17 Annex D 2008 Edition NATIONAL ELECTRICAL CODF 70-787 Branch circuits INDEX Color code,210.5 Building component Overcurrent protection,368.17 Aerial,820.44, 830.44 Common area,210,25 Definition,545.2 Over 600 volts,368-IV Armored(Type AC),see Ar- Conductors,minimum ampacity Building system Reduction in size,368.17(8) mored cable(Type AC) and size,210.19 Definition,545.2 Support,369.30 Border lights,theater,520.44(B) Critical,517.33,517.43 Building wire,see Conductors Under 600 volts,368.240 Bundled Definition,517.2 Bulk storage plants,Art,515.see Through walls and floors, Definition,520.2 Critical operations power sys- also Hazardous(classi- 368.10(C) CATV Art 820 tems,708-11 fied)locations Uses not permitted,368.12 Continuity,300.12 Definition,Art. 100-I Class I locations,515.3 Uses permitted,368.10 Definition, 800.2 Fixed electric space-heating Definition,515.2 Bypass isolation switch,700.6(B), Flat cable assemblies(Type FC), equipment.424,3 Gasoline dispensing,515.10 701,7(B l see Flat cable assem- General,210-1 Grounding and bonding,515.16 Definition,Art. 100-I blies(Type FC) General-purpose Sealing,515.9 Flat conductor(Type FCC),see Definition,Art. 100-1 Underground wiring,515.8 Flat conductor cable Guest rooms or suites,2I0.6(A), Wiring and equipment,515.4, _C_ (Type FCC) 210.18 515.7 Cabinets,cutout boxes,and Flexible,see Cords, Flexible Health care facilities,517.18(A), Bull switches meter socket enclo- Grouped 517.63(B),517.63(C) Definition,530.2 sures,Art,312 Definition,520.2 Individual Burglar alarm systems,see Construction specifications, Heating,see Heating cables Definition.Art, 1(1(1-I Remote-control,signal- 312-I1 Installation in cable trays,392.8 Overcurrent protection, ing,and power-limited Damp and wet circuits locations, 312.2 Installed in grooves, 300.4(F) 210.20 Definitions,Art. 100-1 Instrumentation tra y(Type ITC), bars Permissible loads, 21f).23 Bus Deflection of conductors, 312.6 see Instrumentation tray Rating or setting,430.52 Aboveground wiring methods, Installation,312-I cable(Type ITC) Required,490.72, 300.37 Insulation at bushings,300,4(G}, Integrated gas spacer cable 520.53(F)(2),600.5, Industrial control panels, 312.6(C) (Type 102 (Type)GS),see Inte- 605.8(B),620.22 to Position in walls,312.3 grated gas spacer cable Motor control centers,430.97 620.25 Switch enclosures,splices, taps, ('Type IGS) 5[408 . Infrared lamps,422.14 Switchboards, 312.9 Medium voltage cable[Type Bushings Isolated power systems,517,160 Bus gs Unused openings, [{O.12(A) MV),see Medium volt- Cord,luminaire,410.84 g.p age cable(Type MV) Maximum loads,220.18 Wire-bending space at Terminals, Mobile homes,550.11,550.12 Fiber,see Fiber bushings 312.6(B) Generators 44516 Meta]-clad cable(Type,MC), , . Motor,on individual branch cir- Wiring space,side or back, see Metal-clad cable suit,see Motors High density polyethylene con- 312.9 duit,353.46 Cable bending, type (Type MC) Muhiwire,210.4,501.40, g,see[ of cable Mineral-insulated metal-sheathed 502.40,505.21 Insulated,300.4(G),312.6(0} Cablebus,Art.370 (Type MI),see Mineral- Definition,Art. 100-1 Lampholders attached to flex- Conductors,370.4 insulated metal-sheathed ible cord,410,62(A) Overcurrent protection, 370.5 Outside,see Outside branch cir- Securing fittings or raceways, Termination.P cable(Type ype MI) suits and feeders 300.4(G) Multiconductor cables,identifi- roundin Overcurrent device, Definition,370.2 cation of conductors in, Intermediate metal conduit, Equipment 240.24fB)(2) 342.46 g g conductor 250.119(B) Definition,Art. 100-I installation, 250.120{A)Motors,430.13 Fillings,370.7 Nonmetallic extension,see Non- Overcurrent protection,210.20, Outlet boxes,conduit bodies, Grounding,370.9 metallic extensions 240.4 Nonmetallic-sheathed{Types and outlet fittings, Marking,370.10 Patient bed location,517.18(A), 314.17(D).314.42 Support and extension through NM,NMC,and NMS), 517.19(A) Reinforced thermosetting resin walls and floors,370.6 see Nonmetallic- Permissible loads,210.23 conduit,355.46 Use,370.3 sheathed cable(Types Ratings,210.3,210-11 Rigid metal conduit,344.46 NM,NMC,and NMS) Recreational vehicles,551.42 g Cable connectors Rigid polyvinyl chloride con- Definition,324.2 Nonmetallic underground con- Requirements far,Table 210.24 Lit, 352.46 Theater,520.67 duit with conductors, Selection current,440A(C) Snow-melting and deicing Cable end fittings, ee Nonmetallic under- Definition,440.2 equipment,426.22(C) cable to knob-and- � Small-appliance,210.11(C)(1) Underground installations, tube,300.16(A) conductors Stage or set,530.23 300.5(H) Cable management system, Optical fiber,see Optical fiber Taps from,210.19(A),Table Use in lieu of box or terminal 626.23 cables 210.24,240.4(E), fitting,300.16(B) Definition,626.2 Other types of,see names of 240.5(B)(2) Busways,Art.368 Cables systems Through luminaires,410.11, Branches from,368.56 Abandoned, 820.25, 830.25 Point of entrance 410.64 Construction,368-III Coaxial Definition,800.2, 820.2, Two or more outlets on,210.24 Dead ends closed,368.58 Definition, 820.2 830.2 Voltage drop,210.19(A)FPN Definition,368.2 Communications,800.25 Portable,see Cords,flexible No.4 Extension through walls and Definition, 800.2 Power and control tray cable Voltage limitations,210.6 floors, 368.10(0) Fire alarm,760,25 (Type TC),see Power X-ray equipment,517-V,660.4, Feeder or branch circuits, Definition,760.2 and control tray cable 660.6(A) 368.17 Interconnecting (Type TC) Branch-circuit selection current Grounding,368.60 Definition,645.2 Preassembled in nonmetallic Definition,440.2 Over 600 volts,368.260 Network-powered broadband conduit,see Nonmetal- Marking on nameplate,440.4(C) Installation,368-11 communication lie underground conduit Building Luminaires connected to, Definition, 830.2 with conductors Definition,Art. 100-1 410,36(F) Optical fiber,770.25 Protection against physical First floor of,362,10 Marking,368.120,368.320 Definition,770.2 damage,300.4 70-•788 NATIONAL ELECTRICAL CODE 2008 Edition INDEX Circuits Seating,501.15(D),501.15(E), Capacitors,Art.460.see also Cell line,electrolytic cells General, 110.9,240-1 505.16(A)(2), Hazardous(classified) Attachments and auxiliary Indicating,404.7 505.16(B)(5), locations equipment Overcurrent protection,230,208, 505.16(B)(6), Enclosing and guarding,460.2 Definition, 668.2 240-1,240-VII 505.16(B)(7), induction and dielectric heating, Definition,668.2 Generators,445.12 505.16(C)(2) 665.24 Cellular concrete floor raceways, Motors,250.122(D), Secured,300.11,314,17(B) 600 volts and under,460-I Art. 372 430.52(A),430.58, and(C) Conductors,460.8 Ampacity of conductors, 372.17 430.110,430.111 Service,see also Service- Grounding,460.10 Connection to cabinets and other Transformers,450.3 entrance cable iTypes Marking,460.12 enclosures,372.6 Panelboards,408-III,408,54, SE and USE) Means for discharge,460.6 Definitions,372.2 408.55 Ex.! Definition,Art. 100-I Overcurrent protection, Discontinued outlets,372-13 Rating 460.8(B) Header,372.5 Fixed-trip circuit breakers, Service-entrance(Types SE and P USE),see Service- Rating or setting of motor Inserts,372.9 240.6(A),240,83(C), overload device,460.9 Junction boxes,372.7 240.86 entrance cable{Types Phase converters,455.23 Markers,372.8 Motor branch circuits,430.58 5E and USE) Over 600 volts,460-I1 Number of conductors, 372.11 Service disconnecting means, Splices in boxes, 300.15 Grounding,460.27 Size of conductors,372.10 230.70,230,205 Stage,530.18(A) Identification,460.26 Splices and taps,372.12 Service overcurrent protection, Through studs,joists,rafters, Means for discharge,460.28 Uses not permitted, 372.4 230.90,230.91 300.4 Overcurrent protection, Cellular metal floor raceways, Switches,use as,240.83(D), Traveling,elevator,620.11(B), 46025 Art.374 404,11,410.141(A) 620.12(A), 620-V Switching,460.24 Ampacity of conductors. 374.17 Circuit directory,panelboards, Underground,230-1I1,300.5. X-ray equipment,660.36 Connection to cabinets and 110.22 300.50 extension from cells, Caps,see Attachment plugs Circuit interrupters,ground- Underground feeder and branch Carnivals,circuses,fairs,and 374.11 fault,see Ground-fault circuit Type UF,see similar events,Art.525 Construction,374-11 circuit interrupters Underground feeder and Conductor overhead clearance, Definitions,374.2 Circuits branch-circuit cable 525.5 Discontinued outlets,374.7 Abandoned supply circuits 10 374. (Type UF) Definitions,525.2 Inserts, Definition,645.2 Vehicle supply equipment, Grounding d bonding,525-IV Installation,374-1 Junction b ,374.4 Anesthetizing locations.517.63 boxes,625.17 Equipment bonding,525.30 Junction Branch,see Branch circuits , oxen Welding,630-IV Equipment grounding,525.31 Burglar alarm,see Remote- Cable sheath Grounding conductor continu- Number of conductors, 374.5 control,signaling,and Definition,770.2,800.2 ity assurance.525.32 Size of conductors,374.4 power-limited circuits Splices and taps.374.6 Cable suspension,300.19 Power sources,525--II Uses not permitted.374.3 Central station,see Fire alarm Cable trays,Art. 392 Multiple sources or supply. Chairlifts,see Elevators,dumb- systems Ampacity, 392.11,392.!3 525.11 waiters,escalators,mov- Communication,see Communi- Cable fill,392.9,392.10,392.12 Services,525.10 cations circuits ing walks,platform lifts, Cable installation,392.8 Protection of electrical equip- and stairway chairlifts Control,see Control circuits Constructions specifications, ment,525.6,525.23 Fire alarm Pe Churches,Art.518 392.5 Wiring methods,525-III Cinder fill Circuits extending beyond Definition, 392.2 Concessions,525.21 High density polyethylene con- one building,760.32 Equipment grounding conductor Ground-fault circuit- duit,353.10(3) Definitions,760.2 installation,250.120(A) interrupter protection, Intermediate or rigid metal con- Fuel cell systems,692-11 Grounding,392.7 525.23 duits and electrical me- Grounding,Art.250 Installation, 392.6 Portable distribution or termi- tallic tubing,in or un- Impedance, 110.10 Uses not permitted,342.4 nal boxes,525.22 der,342.10(Cl, Information technology equip- Rides,525.21 ment,645.5 Uses permitted,230.44,392.3 344.10(C} round con- Intrinsically safe,504.30 21 525 , . Nonmetallic under Ventilated,392.9(E),392.10 Tents g Calculations,Annex D;see also Cartridge fuses,240-VI duit with conductors, Definition,504.2 Loads Disconnection,240.40 354.10 Inverter input and output cir- CATV systems,see Community Reinforcing thermosetting resin cuits,690.1,690.6• Camping trailer,see also Recce- antenna television and conduit,355.10(C) 690.8,690.10 ationa! vehicles(camp- radio distribution Definitions,690.2 ing trailers,motor Rigid polyvinyl chloride can- homes,part trailers, (CATV)systems duit, 352.10(C) Less than 50 volts,Art.720 Ceiling fans,680.22(C),680.43(B) Circuit breakers,Art.240.see Class 1,725--11 travel trailers,truck Support of,314.27(D),422.18 Grounding,250.20(A) campers) PPo also Hazardous fclassi- $� Cell fied)locations Mare than 600 volts,see Over Definition,551.2 Cellular concrete floor raceways Accessibility and grouping, 600 volts Canopies Definition,372.2 Boxes and fittings,314.25 X4.8 Motor,430.11 g Cellular metal floor raceways, Circuits over 600 volts,490.21, Motor control,430-VI Live parts,exposed,410.5 374,2 490.45,490.46 Definition,430.2 Luminaires Electrolytic,see Electrolytic Damp or wet locations, in, Number of,in enclosures, Conductors,space for,410.20 cells 404.4 90.8(B) Cover Sealed,storage batteries, Definition,Art. 100-1, Photovoltaic output,690.1. At boxes,410.22 480.6(D),480.10(B) Art,100-I1 690.7,690.8 Combustible finishes,cov- Definition,480.2 Disconnection of grounded Definition,690.2 ering required between Solar circuits,404.2(B), Photovoltaic source,690.1, canopy and box,410.23 Definition,690.2 514.11(A) 690.6 to 690.9 Mechanical strength,410.78 Cellars,see Basements Enclosures,404.3 Definition,690.2 2008 Edition NATIONAL ELECTRICAL CODE 70-789 Circuits INDEX Power-limited,see Remote- Clothes dryers Overhead,800.44 Mobile homes,820.106 control, signaling,and Calculations for,220.53 Within buildings,800-V Protection, 820-III, power-limited circuits Feeder demand factors,Table Critical operations power sys- 820.100(A)(6) Protectors required,800.50, 220.54,220.82(B)(1) tems,708.14 Raceways, 820.133, 820.154, 800.90, 800.100, Grounding,250.114(3),250.140 Definitions,800.2 820,182 800.106, 800.170, Mobile homes,550.15(E), Essential electrical systems, Compressors, refrigeration,Art. 830.90 550.16(A)(1) 517.32(D),517A2(D) 440 Remote-control,see Remote- Clothing manufacturing plants, Grounding,800.93,800-IV Computer rooms,see Information control,signaling,and 500.5(D),Art.503,Art. Health care facilities,517.32(D), technology equipment power-limited circuits 506.see also Hazardous 517.42(D),517--VI Concealed Signal,see Remote-control,sig- (classified)locations Hybrid power and communica- Definition, Art. 100-1 nalin g�and power- CO/ALR tions cables,800.3(C), Knob-and-tube wiring,see limited circuits Receptacles,406,2(C) 800,154(F),800.179(1) Knob-and-tube wiring 800-V Telegraph,see Communications Switches,404.14(C) Installation, Concentric knockouts,see circuits Collector rings,490.54,675.11 Lightning conductors, 800.53 Knockouts Listing of communications wires Telephone,see Communications Definition,675.2 and cables,800.113, Concrete circuits Electrodes encased in,250.50 Collectors,cranes and hoists, $00.179 Underground,see communica- Ex.,254.52(A)(2), 610.22 Listing of equipment,800--18, lions circuits 250.52(A)(3), Ungrounded,210.10,215.7, Color code 800-VI 254.66(B),250.68(A) Branch circuits, 210.5 Mechanical execution of work, 410.93;see also Con- Conductors,310.12,504.80(C), 800.24 Ex.l doctors,ungrounded Mobile homes,800.106 High density polyethylene con- 647.4(C) Circuses,see Carnivals,circuses, Protection,500-1I duit in,353.10 fairs,and similar events Grounded conductor,20(}.6, Liquidtight flexible nonmetallic 200.7,404.22 Devices,800.90 Clamp fill,boxes,314.16(B)(2) Grounding conductor, Grounding, 804.100, conduit, 356.10(7) Clamps,ground,250,10,250,70 250.119,310.12(B), 800.106(A) Metal raceways and equipment Class 1,2,and 3 circuits,see 400.23 Mobile homes,grounding and in, 300.6(A)(3)and(B) Remote-control,signal- Ungrounded,210.5(C), bondin g at,800.106 Nonmetallic underground con- ing,and power-limited 215,12(C),310.12(C) Primary protectors,800.50, duit with conductors, circuits Heating cables,424.35 800.90, 800.100, 354.10 Class C,CI,and I[I locations,see Higher voltage to ground $00,106, 800.170(A), Conductive surfaces,exposed R3D.90 Definition,517.2 Hazardous(classified( Panelboards,408.3(E) Secondary protectors, Conductor fill locations Sensitive electronic equip- 800.90(D),800.170(8) Audio systems, 640.23(A) Clean surfaces,grounding con- ment,647.4(C) Raceways,800.133(A)(1), Auxiliary gutters,366.22 doctor connections, Service-entrance conductors, 800.154, 800,182 Boxes,314.16(B)(1)and(5) 250.12 230.56 Types of cable,804.179 Cable trays,392.9,392.10 Clearances,see also Enclosures: Combustible dusts,Art.502.see Underground circuits entering Cellular concrete floor raceways, Space also Hazardous(classi- buildings,800.47 372.11 Antennas,810.13,810.18, fled)locations Communications equipment Cellular metal floor raceways, 810.54 Combustible gas detection sys- Definition,Art. 100-1 .174.5 Community antenna systems, tems,500.7(K), Community antenna television Control circuits,517.74(A) Art. 820 505.8(K) and radio distribution Electrical metallic tubing, Conductors Definition,500.2,505.2 (CATV)systems, 358.22 Open,outside branch circuits Combustible-liquid produced Art. 820 Electrical nonmetallic tubing, and feeders, 225.18, vapors,see Hazardous Access to electrical equipment, 362.22 225.19 (classified)locations 820.21 Elevators,620.32,620.33 Service drop, 230.24, 230.26 Commercial see Gara g es, Cables Fixture wire,402.7 Live arts Abandoned coaxial, 820.25 P commercial Flexible metal conduit,348.22, Auxiliary tters, 366.100(E) grounding Definition,820.2 mY g Common roundin electrode, Aerial entrance,520.44 Table 348.22 Circuits over 600 volts, see Electrodes,ground- Flexible metallic tubing, 110-III ing,common Within buildings,820-V 360.22(A) Common Luminaires,410.116,410.136 Coaxial neutral Definition,820.2 General installations,300.17 Network-powered broadband Feeders,215.4 Entering buildings, 820.47 Hazardous(classified) locations, communications sys- Outside wiring,225.7(6) Listing, 820.113,820.154, sealing fittings, tems.830.44 Communications circuits,Art. 820-VI 501.15(C)(6), Swimming pools,680.8 800 Outside,820.44 505.16(D)(5) Switchboards,408.5,408.18 Abandoned cables,800.25 Types of, 820.179 High density polyethylene con- Climbing space,line conductors Definition,800.2 Underground,820.47 duit,353.22 on poles,225.14(D) Access to electrical equipment, Definitions, 820.2 Intermediate metal conduit, Clothes closets 800.21 Energy limitations,820.15 342.22 Definition,Art. 100-I Bonding, 800.100(D), Grounding,820-TV Liquidtight flexible metal con- Heating,424.38(C) 800.106(B) Cables,820.93, 820_-IV duit,350.22 Luminaires,410.16 Cable marking,800.113 Equipment,820.143 Liquidtight flexible nonmetallic Overcurrent devices,240.24(D) Cable substitution,800.154(8) Installation of cables and equip- conduit,356.22 Conductors ment,820-V Maximum permitted,300.17 Other circuits with, Locations,820.3 Nonmetallic underground con- 800.154(C) Mechanical execution of work, duit with conductors, 820.24 354.100(D) 70-790 NATIONAL ELECTRICAL CODE 2008 Edition INDEX Conductors Outlet boxes.etc.,314.16 Communications circuits. Grounded Splices and joints, I f0.14(B), Reinforcing thermosetting resin 800-1I, 800-V Alternating current systems, 4(10.9,530.12,590.4(G) conduit,355.22 Concealed knob-and-tube,see 250 24,250.26 Switchboards,408.19 Remote control circuits, 725.51 Knob-and-tube wiring Identification,200.6, 200.7, Theaters,520.42 Rigid metal conduit, 344.22 Conduit or tubing,number in, 210.5(A) Intrinsically safe,504.30,504.50 Rigid polyvinyl chloride con- 342.22,344.12-348.22, Change in size,240.23 Length in boxes,300.14 !? duit,352.22 Table 348.22,350.22, Continuity of,300.13(B) Length in surge protective Signs, 600.31(C) 352.22,353.22,354,22, Definition,Art. 100--1 devices,285.12 St rut-type channel raceway, 356.22.358.22,360.22, Different systems.200.6(D) Lightning rods,spacing from, 384.22 362.22,Chap.9 Tables, Electrode-type boilers,over 250,106 FPN No.2, Surface raceways,386.22, Annex C 600 volts,490.72(E) 800.53, 820.44(17)(3) 388.22 Construction, general,Tables Fuses in,430.36 Liquidtight flexible metal con- Theaters,520.6 310.13(A)through Overcurrent protection, duit,see Liquidtight Underfloor raceways.390.5 310.13(0) 230.90(B),240.22 flexible metal conduit Wireways, 376.22,378.22 Cowling of electric equipment, Separately derived systems, Liquidtight flexible nonmetallic X-ray equipment,660.8 110.13(8) 250.30(A) conduit,see Liquidtight Conductors,see also Cords, flex- Copper. 1 10.5,505.18(A), Services flexible nonmetallic ible-,Fixture wires 760.49(C) Disconnection of,230,70, conduit Adjustment factor for more Ampacities,Tables 310.16 230.75 Metal-clad cable,see Metal-clad through 310.21,Tables Overcurrent protection, cable than three current- P 310.69 through 310.86, 23090(8) Metal enclosures,spacing from , carrying conductors in B.310.1 through li ghinini rods,250.106 raceway,cable,Table B.310.10 Switches,disconnection, b g 4042(B) FPN No. 2 B.310.11 Properties,Chap. 9,Table 8 Use a identification, Art. Mineral-insulated metal-sheathed Aluminum.conductor material, Copper-clad aluminum Z cable,see Mineral- 250.120(B),310.14 Definition,Art. 100-1 insulated metal-sheathed Grounded power sysizms in Aluminum.properties of,Chap. Equipment-grounding con cable(Type MI) anesthetizing locations, 9.Table 8 ductors, 250.120(B) 517.63 Minimum size,230.42,310.5, Ampacitics of,310.15,Tables Cords, flexible,see Cords, 517.74(B).620.12, Grounding,see Grounding con- 310.I6 through 310.21, flexible doctors 650.6(A),660.9, Tables 310.69 through Corrosive conditions,see Corro- 725.49(A),760.49(A), 310.86, B.310.1 through Grounding electrode,see g live conditions Grounding electrode 760.142,810.17,810,53 8,310.10 Covered conductors Motion picture projectors,sizes, Amusement attractions,522.20 Definition,Art. 100-1 540,13 Grouped through 522.24 Crane and hoists,610-II,610- Definition,520,2 Motor circuits,430.6,430-11 Applications,310.13 111,610.41 Identification,310.1 2 Multioutlet assembly,see Multi- Armored cable,Type AC,see Damp locations.310.8(8),Table outlet assembly Induction and dielectric healing Armored cable(Type 310.13(A) equipment,ampacity of Multiple, 250.301A)(8)(b), AC) Definitions,ArL IL*-1 supply,665.10 250.102(C).250.122(F). � Bare,see Bare conductors Deflection of,see Deflection of 300.5(1)Ex. I,300._0, Bending radius, 300,34 conductors Industrial control panels,409.20 Installation with other systems. 3'0.4,392.8(D), Boxes and fittings,junction, Different systems.300.3(C), 300 20.27(A)(2), 314.16,314.17 725.48 620.12(A)(1) Insulated Branch circuits,Art. 210.see Dimensions of,Chap.9,Table 4 Neutral,see Neutral Definition.Art. 10(>-1 also Branch circuits Dry locations,310.8(B),Table Nonmetallic extensions,see Bundied,in theaters,etc. 310.13(A) Lighting systems operating at Nonmetallic extensions 30 volts or less, Definition,520.2 Electrical metallic tubing,see Nonmetallic sheathed cable. Buried, 310.7 Electrical metallic tub- 411.5(D) Types NM,NMC,and ing Insulating materials,310.13 NMS,see Nonmetallic- Busways,.see Busways Insulation,Art. 310 Cabinets and cutout boxes. Electrical nonmetallic tubing, sheathed cable(Types 312.5 through xes.7 see Electrical nonmetal- At bushings,4 AWG and NM, NMC,and NMS) g lic tubing larger,300.4(G), Number of, in,see Conductor Cablebus,see Cablebus Elevators,dumbwaiters,escala- 3120C) fill Calculations,examples,Annex tors,moving walks, Construction and application, Organs,650.6, 6503 D 620-II through 620-IV 310.13 Outlet boxes,temperature limits, Capacitors,460.8 Enclosure,grounding,250-IV Elevators,dumbwaiters,esca- 410.21 Cellular concrete floor raceways, Grounding electrode conduc- lators,moving walks, Outside wiring,Art.225 see Cellular concrete tors,250.64(D), platform lifts,and stair- Overcurrent protection,240.4 floor raceways 250.64(E) way chairiifts,620.11 Cablebus conductors,370.5 Cellular metal floor raceways, Equipment grounding,see Fire alarm systems. Grounded conductors, .tee Cellular metal floor Equipment grounding 760.49(8) 230.90(B),240.22 raceways conductors Fixtures,410.52,410.117(A) Service-entrance conductors, Circuit Feeder,Art. 215 Hazardous(classified)Iota- 230.90,230.91,230.208 Communications,Art. 800 Fire alarm systems,760.48, Lions,501.20,505.18(B) Overhead,800.44 Control,health care facilities, 760,49,760.130 Identification,310.12 Over 6W volts,Art.490 517.74 Fixture wires,Art.402 Line-type fire detectors, Paralleled,250.30(A)(8)(b). Fire alarm,Art.760 In free air,Tables 310.17, 760.179(!) 250.102(C),250.122(F), Less than 50 volts,Art.720 310.19,310.21 Marking,310.11 300.50)Ex. 1,300.20, Over 600 volts,Art.490 Gauges(AWG),general provi- Motion picture projectors, 310,4,392.8(D), Signal,remote-control, sions, 110.6 540.14 520.27(A)(2), power-limited-Art. 725 General wiring,Art. 310 Service conductors.230.22, 620,12(A)(1) Combinations,Chap. 9,Table I Generators,size,445.13 230,30,230.41 Pendant fixtures,410.54 2008 Edition NATIONAL ELECTRICAL CODE 70-791 Conductors INDEX Properties of,Chap.9,Table 8 Welders,electric Rigid polyvinyl chloride, see Continuity Raceways,number of conduc- Ampacity of supply,630.11. Rigid polyvinyl chloride Electrical tors in,see Conductor 630.31 conduit Equipment grounding con. fill Overcurrent protection, Connections ductors,250.124 Radio and television 630.12(B),630.32(B) Aluminum,copper conductors, Grounded conductors, Antenna distribution systems, Wet locations,225.4,310.8(C), 110.14 200.2(B) 810.4,Art.820 Table 310.13(A) Cellular metal floor raceways to Gutters,auxiliary,366.100(A) Antenna systems,Art.810 Wireways,see Wireways,metal; cabinets and extensions. Metal raceways and cables, Equipment,Art. 810 Wireways,nonmetallic 374.11 250.96,250.97,300.10 Railway,power and light from, X-ray equipment,517-V,660.6 Essential electrical systems, Service equipment, 110.19 through 660.9 517.34,517.42,517.43, 250.92(B), 250.94 Recreational vehicle site feeder Conduit bodies,see also Boxes 517.45 Wireways,376.100(A) circuit,551.73, (outlet,device,pull,and Fuel cell systems to other cir- Grounding, metal boxes, 551.80 junction) cuits,692-VII grounding-type recep- Definition,551,2 Definition,Art. 100-1 Grounding conductor,250-III, tacles, 250.148 Remote-control circuits,Art. Number of conductors, 250-VI Mechanical 725 314.16(C) High-impedance grounded neu- Gutters,auxiliary,366.100(A) Rigid metal conduit,see Rigid Pull and,junction box,314.28 tral system,250.186(C) Raceways and cables,300.10, metal conduit Short radius,314.5 Integrity of, 110,12(B) 300.12 Same circuit,300.5(1) Support of Multiple circuit,see Multiple Conductors,300.13 Selection of.examples, Cable trays,392.6(4) circuit connections. Grounded conductor of Annex D By reinforcing thermosetting grounding multiwire circuits, Service,see also Service- resin conduit,355.10(H) Point of interconnected power 300,13(B) entrance cable(Types By rigid nonmetallic conduit, production sources, Wireways,376.100(A) SE and USE);Service- 352.10(H) 705.12 Continuous duty entrance conductors Conduit fill,see also Conductor Splices, 110.14(B) Definition,Art. 100-1 Definition,Art. 100-I fill Switches,404.2 Continuous industrial processes Service-entrance,see Service- Equipment grounding conduc- Temperature limitations, Coordination,electrical system, entrance conductors tors,Chap.9,Note 3 to 110.14(C), 110.40 240.12 Signal circuits,Art,725, Table 1 Terminals,general provisions. Ground-fault protection. Art.760 Grounding conductor, 110.14(A) 230.95 Ex. Signs and outline lighting, 310.15(B)(5) X-ray installations,517.71 Orderly shutdown,430.44 600.31,600.32 Conduit nipples,Chap.9,Note 4 Connectors Power loss hazard.240.4(A) Single, 392.3(B)(1),392.8(E), to Table 1 Armored cable,320.40 Continuous load 392.10,392.11(B), Conduits Boxes,314.17 Applications, 210.19(A), 392.11(C),392.13(B) Boxes supporting,314.23(H)(2) Cabinets and cutout boxes, 210.20(A),215.2(A) Sizes, 110.6,Chap.9,Tables 5 Circuits,physical protection of 312.5(C) Definition,Art. 100-I and 5A;see also remote control, Cable Control,see also Hazardous(clas- subhead:Minimum size 725.31(B) Definition,324.2 sified) locations Spliced,230.33, 230.46 Remote P Conductors,number in,Chap.9, Theater,520.67 Circuits,see Remote-control, Stranded,310.3 Table 1,Annex C, Electrical metallic tubing, Support of,in vertical raceways, Tables Cl through 358.42 signaling,and power- 300.19 C12(A) Electric vehicle,625.19 limited circuits see Y Surface raceway, Strut-type Dimensions,Cho p Of induction and dielectric 9,Table 4 Definition,625.2 channel raceway;Sur- Electrical metallic tubing,see Flexible metal conduit,348.42 heatin g equipment, face metal raceways; 665.7 Electrical metallic Intermediate metal conduit, equipment,Surface nonmetallic tubing 342.42 X-ray 517-V,660-11 raceways Control centers Electrical nonmetallic tubing, Liquidtight flexible metal con- Flash rotection. 110.16 Switchboards and panelboards, see Electrical nonmetal- duit,350.42 P 405.3(A),408.19 Guarding live parts, 110.27 tic tubing Liquidtight flexible nonmetallic Headroom, 110.26(E), 110.32 Temperature,limitations of, Flexible metal,see Flexible conduit,356.42 Illumination at, 110.26(D), 310.10,338.10(B)(3) metal conduit Pressure(solderless) 110,34(D) Theaters,portable stage equip- High density polyethylene con- Definition,Art. 100-1 Motor,430-VIII ment,520.68 duit(Type HDPE),see Rigid metal conduit,314.42 Definition, 100-1 Tunnels, 110.53, 110.54 High density polyethyl- Single-pole separable Workin s aces about, 110.26 Underfloor raceway,see Under- ene conduit(Type Definition,530.2 g P floor raceways Working space, 110 110.32 HDPE} Constant-voltage generators,Art. throu h 110.34.34 Underground feeder and branch- g Intermediate metal,see Intemte- 445 Control circuits 43 circuit cable,see Under- 0-VI diate metal conduit Overcurrent protection for, Amusement attractions,522-II, ground Feeder and Liquidtight flexible metal,see 445.12(A) 522--III branch-circuit cable Liquidtight flexible Construction,closed Definition,409.2,430.2,522.2 (Type UF) metal conduit Definition,545.2 Control drawing,504.10(A) Ungrounded g. Liquidtight flexible nonmetallic, Construction,types of,Annex E Definition,500.2,544,2 Identification,210.5(C), see Liquidtight flexible Construction sites Controllers,see also Hazardous 215.12(C) nonmetallic conduit Assured equipment grounding (classified)locations Insulated fittings, 300.4(G) Metallic,grounding runs 7.5 in conductor program, Cases, roundin 250.112(D) Overcurrent protection, (25 ft),250.86 Ex.l 590.6(B)(2) Definition,Art. 100-1,430.2 240.15 Number of fixture wires in, Extension cord sets,590.6(A) Enclosures,grounding, Services,230.90(A) 402.7 and(B)(2) 250.112(D) Tapped from grounded Outside wiring,225.10 Ground-Fault circuit interrupter, Motion system,2 10.10 Ri id metal,see Rigid metal Rigid protection for,590.6(A) Definition,620.2 conduit and(B)(1) Motor,430-VII 70-792 NATIONAL ELECTRICAL CODE 2008 Edition INDEX DC systems Definition,620.2 Audio signal processing,am- Reinforcing thermosetting resin Grounding,708.20(C) Disconnecting means,430.75, plificatiou,and repro- conduit,355.10(B) Overcurrent protection,708-IV 430-IX,430.227 duction equipment Countertops,outlets,210.52(C), Physical security,708.5 Electrically operated pool grouping conductors, 406.4(E) Power sources and connection, covers,680.27(B)(1) 640.8,640.42,640.45 Ground-fault circuit interrupters, 708-II1 Hazardous(classified)loea- Equipment grounding con- 210.8(A)(6) Risk assessment,708,4 tons,501.115,502.115, ductor in,size of, Couplings System performance and analy- 503.115 250.122(E) Electrical metallic tubing, sis,708-V Marking,430.8 Hazardous(classified)loca- 358.42 Testing and maintenance,708.6, Tunnels, 110.55 lions, 505.17,506.17 Intermediate metal conduit, 708,8 Operation Identified conductors within, 342.42 Cross sectional areas Definition,620.2 200.6(C),250.119(0), Liquidtight flexible nonmetallic Conductors,Chap.9,Tables 5 Ratings.430.83 400.22,400.23 conduit,356.42 through 8 Resistors and reactors,see Lampholders,insulating bush- Rigid metal conduit,344.42 Conduits,Chap.9,Table 4 Resistors and reactors ings,410.62(A) Rigid polyvinyl chloride con- Current-carrying capacities,see Control panels,see also Industrial Marking,400.6 duit,expansion fittings, Ampaciriec control panels Minimum size,400.12 352.44 Current-limiting devices,see also Working space, 110.26 Motion picture projectors, Running threads at,342.42(B), Circuit breakers;Fuses Control room 540.15 344.42(B) Definition,240.2 Branch circuits, lighting and Outlets,required,210.50(B) Threaded and threadless, Curtain machines,theaters, receptacles,620.23 Overcurrent protection,240.5, 250.92(B) 520.48 Definition.620.2 400.13 Cove lighting,space for,410.18 Cutout bases see Fuseholders Wiring,620.21(A)(3) Over 600 volts,400-I11 Covers Cutout boxes,see also Cabinets, Control space Power-limited and signal cir- Auxiliary gutter,,366.100(D) cutout boxes,and meter Branch circuits,lighting and cuits,remote-control, Boxes and fittings,314.25, socket enclosures receptacles,620.23 725.49(A) 314.28(C),314.41, Definition,Art. 100-1 Definition,620.2 Pull at joints and terminals, 314.42,314.72(E) Cutting tables,motion picture, Wiring,620.21(A)(3) 4(]0.10 Cable,650.6(D) 530-IV Control system Repair of,hard service,400.9 Faceplates,see Faceplates Definition,620.2 Solar photovoltaic systems, Pool cover,zlectrically operated, Convenience outlets,.see 690.31(C) 680.27(B) Definition,680.2 -D- Receptacles Splices and taps,400.9, Strut-type channel raceways, Dampers(flue),control Conversion table,AC conductor and(B,530.12(4} 384.100(C) Fixed stage equipment,smoke resistances and Table and fB) Wireways,376.2,376.56(8)(4), ventilator control, tances,Chap. 9,Table 9 Construction sites, 376,100(D),378.2 520.49 Converters 590.4(G) Cranes,Art.610;see also Hoists Ventilating openings,trans- Phase,ion, hale Swimming pools,fountains, Conductors,610-11,610-III former vaults,450.45(E) Phase,see Phase converters and similar installations, Control,610-VI Damp or wet locations, 110.H, Recreational vehicle 680.7, (A)f5), Disconnecting means,430.112 see also Wet locations Definition.551.2 660.23(BB)(3})(3),, Ex.,610-IV Boxes and fittings,314.15 Cooking unit,counter-mounted, 680.42(A),680.55(B), Electrolytic cells,668.32 Busways,368.12(D) see also Ovens,wall- 680.56 Flexible cords,400.7(A)(5) Cabinets and cutout boxes, mounted; Ranges Types,Table 400.4 Grounding,250.22(1), 312,2 Branch circuits,210.19(A)(3), Uses not permitted,400.8 250.112(E),250.116(1), Cablebus,370.3 210.23(C).Note 4 to Uses permitted,400.7 610-VII Conductors,types,310.8.Table Table 220.55 Heater,Table 400.4,422.43(A) Hazardous(classified)locations, 310.13(A) Definition,Art. 100-1 Tinsel 503.155,610.3(A) Definition,Art. 10(-I Feeders,calculation of load, Overcurrent protection, Marinas and boatyards,555.23 Electric signs and outline light- 220.82(B)(1) 400.13 Motors and controllers,discon- ing,600.42(G), Grounding, 250.140 Types,Table 400.4 necting means. 600.42(H)(2) Cooling of equipment, 110.13(B) Cord sets,see Extension cord sets 430.112 Ex. Fixed electric space-healing Coordination,electrical systems, Correction factors,ambient tem- Overcurrent protection.610-V equipment,424.12(B) 240.12 perature,Tables Critical branch,517.33,517.43 Lampholders,410.96 Definition,Art. 100-1 B.310.1 through Definition,517.2 Luminaires,410.101A) Feeders.240.100(C),517.17(B) B.310.10,Tables 310.16 Critical care areas,517.19 Open wiring,398.15(B) Overcurrent protective devices through 310,20 Definition,517.2 Overcurrent protection,cnclo- Emergency systems,700.27 Corrosion protection,see Protec- Critical operations power sys- sure,240.32 Legally required standby sys- tion,corrosion tems,Art.708,Annex F Panelboards,408.37 tems,701.18 Corrosive conditions,398.15(B) Availability and reliability Receptacles,406.8 Copper-clad aluminum conduc- Bushing,430.13 for,Annex F-I Reinforcing thermosetting resin tors,see Conductors, Cablebus,370.3 Circuit wiring and equipment, conduit, 355.10(E) copper-clad aluminum Conductors and conductor insu- 708--11 Rigid polyvinyl chloride con- Copper conductors,see Conduc- lation,300.6,310.9, Commissioning,708.8 duit,352.10(D)and(E) tors,copper 505.18(B) Definition,708.2 Switchboards,408.16 Cord connectors,626.25(B)(5) High density polyethylene Definitions,708.2 Switches,404.4 Definition, 626.2 conduit,353.10(2) Development and implementa- Dance halls,Art.518 Cords,see also Hazardous(classi- Rigid polyvinyl chloride con- tion of functional per- Data processing systems,see In- tied)locations duit,352.10(8) formance tests(FPTs), formation technology Flexible,Art.400,422,16, Deteriorating agents, 110.11 Annex F-II equipment 422.43 Nonmetallic wireways, Emergency operations plan, DC systems,250-VIII Ampacities,Table 400.5 378.10(2) 708.64 Grounding,250.162,250.164 2008 Edition NATIONAL ELECTRICAL CODE 70-793 DC systems INDEX Luminaires,installation of, Elevators,dumbwaiters, Dip tanks,Art.516 Industrial control panels,409.30 410.134 escalators,etc. Direct burial Industrial machinery,670.4(B) Dead ends Control system,Fig. 620.2 Ampacities,modification of, Information technology equip- Busways, 368.58 Single line diagram.Fig. 310.60(C)(2),Tables ment, 645.4(1).645.10 Cablebus,370.7(2) 620.13 310.81 through 310.85 Interconnected electric power Flat cable assemblies,322.40(A) Feeders. 215.5 Corrosion protection production sources, Wireways,376.58,378.58 Generator field control, Fig. D.9 Aluminum metal equipment, 705.20 through 705.22 Dead front Hazardous(classified)locations, 300.6(B) Irrigation machines,675.8 Definition,An. IW-I,551.2 Class 1,Zones 0, 1,and Fen•ous metal equipment, Luminaires,fluorescent, Instruments,meters,and relays 2,marking,505.9(C)(2) 300.6(A)(3) 410.130(G) on,250.174(B) Hazardous(classified)locations Grounding conductor connec- Marinas and boatyards,555.17 Recreational vehicles.551.2, adjacent to dispensers. Lion,250.68(A) Ex. 1, Mobile homes, 550.11 55L45(C) Fig.514.3 250.70 Motors and controllers,430.75. Stage switchboards,520.21 Luminaires,closet storage space, High density polyethylene con- 430.95,430-IX, Working spaces about, Fig.410.2 duit,353.10 430.128,430,227 110.26(A)(1) Marine terminal handling flam- Liquidtight flexible metal con- Naturally and artificially made Definitions,Art. 100 mable liquids.Fig, duit,350.I0(3),350.120 bodies of water,electri- Deflection of conductors 515.3 Liquidtight flexible noometallic cal equipment for, Auxiliary gutters,366.58(A) Mobile homes,receptacle and conduit,356.10(4) 682.14 Cabinets and cutout loxes, attachment plug, Fig. Nonmetallic underground con- Outside branch circuits,see Out- 312.6 550.10(C) duit with conductors, side branch circuits and Deicing installations,.see Fixed Motor feeder and branch cir- 354.10 feeders outdoor electric deicing cuits,Fig.430.1 Over 600 volts,300.50 Parking space_626.22(D), and snow-melting Park trailers,receptacles and Rigid metal conduit, 626.24(C),626.3](A) equipment attachment plugs,Fig. 344.10(A)(2),344.10(B) Delnition,626.2 Delta breakers,408.36(C) 552.44(C) Rigid polyvinyl chloride con- Phase converters,455.8,455.20 Delta-connected Recreational vehicles,recep- duit,Table 300.5, Pools, spas,and hot tubs,680.12 Identifying high-leg,3-phase tacles and attachment 300.50,352.10(G) Portable equipment,517.17(C) supply,4-wire, 110.15. plugs,Fig.551.46(C) Bulk storage plants,515.8 Receptacles,cord connectors 230.56,408.3(E), Remote control,signaling.and Service stations,514.8 and attachment plugs 408.3(F),409.102 power limited circuits, Underground feeder and branch- (caps),422.33,440.63 Demand factor,see also Loads Class 2 and 3 circuits, circuit cable,340.10(1) Recreational vehicle parks, Definition,Art. 100-1 Fig.725.121 Underground service cable, 55I.77(B) Detached buildings,oil-insulated Services,Fig,230.1 230.30 Ex.,Table 300.5, Recreational vehicles,551.45(C) transformers in,450.26 Solar photovoltaic systems, 310.7 Sensitive electronic equipment, Ex.5 identification of compo- Disconnecting means lighting equipment, Detearing equipment,electro- nents, Fig.690.](A)and Agricultural buildings,547,9 647.8(A) static,516.4(E) (B) Air-conditioning and refrigerat- Separate building on same pre- Spray application,dipping,and ing equipment.440.63, mises.250.32(0) Deteriorating agents, l l coating.Figs. 440-1I Services,230-VI, 250.64(D) Device,see also Receptacles; 516,3(0)(1),(C)(2), Appliances,422--III Connections, ahead of, Switches (C)(4),and(C)(5) Capacitors,460.8(C) 230.82 Definition,Art. 100-1 Swimming pools,clearance Cranes,430.112 Ex.,610-IV Over 600 volts, 225.51 Device or equipment fill for from pool structures, Definitions, Art. 100-I, through 225.53, boxes,314.16(B)(4) Fig.680.8 Art.100-II,551.2 230.205, 230.206 Diagnostic equipment,517.73(A) Dielectric heating,see also Induc- Electric deicing,snow-melting Shore power connections, Diagrams tion and dielectric heat- equipment,426.50 555.17 Adjustable speed drive control, ing equipment Electric pipeline,vessel heating Signs and outline fighting, 600.6 Fig.D.10 Definition,665.2 equipment,427.55 Solar photovoltaic systems, Autotransformer overcurrent Different systems,conductors in Electric space heating equip- 690-III protection,Fig.450.4 same enclosure, ment,424-III Standby systems,optional, Cable installation dimensions. 300.3(C),725.48, Electric vehicle charging system 702.11 underground,Fig, 725.136(B),760.48, equipment,625.23 Storage batteries,480.5 310.60 for use with 760,)36, 800.47(A), Electrolytic cells,668.13 Temporary circuits,590.4(E) Tables 310.77 through 800.133(A), 810.18(C), Electroplating systems,669.8 Thermal cutouts, 240.40 310.86,Figs.B.310.2 820.133(A) Elevators, 620-VI,620.91(C) Tunnels, 110.58 through B.310.5 for use Dimensions Fire pumps,695.4(B) Welders,630.13,630.33 with Tables B.310.5 Conductors,Chap. 9,Tables 5 Fixed electric heating equipment X-ray equipment,517.72.660.5, through B.310.10 through 8 for pipelines and ves- 660.24 Cable substitution hierarchy Conduits and tubing,Chap.9, sels,427.55 Discontinued outlets,.see Outlets, Communications systems, Table 4 Fixed outdoor electric deicing discontinued Fig.800.154(E) Dimmers and snow-melting Dissimilar metals,see Metals, Community antenna TV and Emergency lighting circuits, equipment,426.50 dissimilar radio distribution sys- 700,23 Fuel cell systems,see Fuel cell Distribution panelboards,see iems.Fig. 820.154(E) Solid-state-type,520.25(D) systems Panelboards Fire alarm systems,Fig. Definition,520.2 Fuses and thermal cutouts, Distribution point,547.9 760.154(D) Stage switchboard,520.25, 240.40 (definition),547.2 Optical fiber cables,Fig. 520.53(E) Generators,445.18 Doors,transformer vaults,450.43 770.154(E) Switch,404.9(B),404.14(E);.See Identification, 110.22, Double insulated Remote control,signaling, also Snap switches 230.70(B),620.51(D) Appliances and tools, 250.114 and power limited cir- Dining areas,essential electrical Induction and dielectric heating Ex.,422.16(B)(1)Ex., cuits,Fig.725.154(G) systems,517.42(E) equipment,665.12 422.16(B)(2)Ex. 70-794 NATIONAL ELECTRICAL-CODE 2008 Edition INDEX Electrodes, grounding Pool pumps,680.21(8),680.31 Dumbwaiters,see Elevators, Installation,358-II Electric power production Double locknuts,see Locknuts, dumbwaiters,escalators, Listing,358.6 sources,see Generators; double,required moving walks,plathinn Marking,358.120 Interconnected electric Drainage lifts,and stairway chair- Maximum number of conductors power production Equipment,50I.15(F), lifts and fixture wires in, sources:Solar photovol- 505.16(E) Dust-ignitionproof 500.7(6), Tables CI and CIA laic systems Oil-insulated outdoor transform- 506.8(A) Number of conductors in, Electric signs,see Signs,electric ers,450.27 Definition,500.2,506.2 358.22 Electric vehicle charging system Raceways,see Raceways, Dusts,see Hazardous(classified) Reaming and threading,358.28 equipment,Art.625 drainage locations Securing and supporting, 358.30 Automatic de-energization, Transformer vaults,450.46 Dusttight,500.7(C),506.8(D) Size, 358.20 625.19 Dressing rooms Definition,Art. 100A,500.2, Splices and taps,358.56 Cable,Table 400.4,625.17 Motion picture studios,530-III 506.2 Uses not permitted. 358.12 Coupler,625.9 Theaters,520-VI Duty, types Uses permitted,358.10 Coupling method,625.16 Drip loops Definitions,Art. 100-1 Wet locations, in,358.10(C) Definitions,625.2 Conductors entering buildings, Doty cycle,welding,630.31(B) Electrical noise,647.3.see also Disconnecting means,625.23 230.24(B)(1),230,52. FPN Sensitive electronic Interactive system,625.26 230.54(F),398.15(B) Dwellings,see also Appliances. equipment Listed,625.5 Service heads,230.54(F) Boxes;Branch circuits; Grounding,250.96(B), Marking,625.15 Driveways Grounding,and similar 250,146(D) Primary source,loss of,625.25 general categories;Lu- Panelboards,408.40 Ex. Clearance of conductors, 225.18 Protection and control 625-IV minaires Receptacles,406.2(D} Clearance of service drop, P Rating,625.14 Branch-circuit voltages, Electrical nonmetallic tubing Supply equipment,230.24(6} g Su I e ui ment,625.[3 210.6(A) (Type ENT),Art. 362 Drop,see Service drops:Voltage Construction,625-III Art.. 100-1 Bends,362.24,362.26 and volts,drop Definition,625.2 220 services,, .102(A), Bushings,362.46 Dryers,clothes,see Clothes dryers Farm Interlock,625.18 220,103 Constructionspecifications,Fry location, l I0,[I;see also Feeder load,calculations for, � Locations,625-V 362-11I Damp or we[fixations Markings,625.15 types, 220,14(1),220.16(A), Definition,362.2 Ventilation not required, Conductors,t s, 310.8,Table 220.82 through 2_0.85, Grounding,362.60 310.13{A) 625.29(0) Annex D Installation,362-II Definition,Art. 100-1 Lighting loads for,Table 220.12 Joints,362.48 Ventilation required,625.29(D), Electric signs,portable or mo- Lighting outlets required, Listing,362.6 Table 6 25.29(D) bile,600.10(D) 210.70(A} Marking,362.120 Voltages,625.4 Electric signs and outline light- Luminaires,410.135, Maximum number of conductors Wiring methods,625-I1 ing,600.42(H)(1) 410,140(B) and fixture wires in, Electric vehicles Nonmetallic extensions, Panelboards as services, Tables C..and C2A Definition,625.2 382.10(2) 408.3(C),408.36 Ex.3 Number of conductors in, Electric welders,see Welders, Open wiring,398.15(A) Receptacle circuits required, 362.22 electric Reinforcing thermosetting resin 210.11 Electrified truck parking space conduit,355.10(E) Receptacle outlets required. Securing and supporting,362.30 equipment,Art.626 P q Size,362.20 Rigid polyvinyl chloride con- 210,52,680.22(A) Definitions,626.2 Splices and taps,362.56 duit,352.10(E) Protection by ground-fault Through metal framing mem- General requirements,626.4 Surface metal raceways, circuit interrupters, Supply equipment,626-III 386.10(1) 210.8(A) tiers,2.28 2) port refrigerated unit Trimming,362.28 Trans g Switchboards,408.20 Swimming pools, Uses not permitted,362,12 (TRU),626-III Dry-type transformers,450.1 Ex. 680.22(A)(3) Uses permitted,362.10 Wiring systems,626-II,626.22 2,450.8(6),450.21, Electric discharge lighting Definition.626.2 450.22 Connection of luminaires, Electrodes,grounding,250.64(F); Dual-voltage motor,locked-rotor -E- 410.24,410.62(C) see also Grounding rating,430.7(8)(3) Eccentric knockouts,see Definition,600.2 electrode conductors Duct heaters,installation or, Knockouts Lamp auxiliary equipment, Aluminum,250.52(B)(2) 424-VI Elbows,metal,protection from 410.104 Common,250.58 Ducts Concrete-encased,250.50 Ex., corrosion,3W.6 Marking,410.146 Definition, 800.2,820.2 Electrical datum plane,555.23, More than 1000 volts,410-XIV 250,52(A)(2), Electrical,310.15,310.60(0), 682.10 to 682,12. Signs and outline lighting, 250.52(A)(3), Fig. 310.60,Tables 682.14ML 682.15 Art.600 250.66(B),250.68(A) 310.77 through 310.80, Definition,555.2,682.2 1000 volts or less,410-XIII EX.] B.310.15(B)(4) Electrical ducts,see Ducts Wiring,equipment,410.130(A), Definition,Art. 100-1 Definition,310.60(A) Electrical life support equipment 410-XIV Gas piping as,250,52(B)(1) Luminaires in,410.10(C) Definition,517.2 Electric heating equipment,fixed, Intrinsically safe apparatus, Wiring in,300.21, 300.22, Electrically operated pool covers, see Fixed electric heat- 504.50(C) 725.3(C),760.3(B), see Covers ing equipment for pipe- Made,250.50,250.52 770.3(B),770.26, Electrical metallic tubing(Type lines and vessels;Fixed Metal frame of building as, 800.133(C), 800.154(A), EMT),Art.358 electric space-heating 250.52(A)(2) 800.179(A), 800.182, Bends,358.24,358.26 equipment;Fixed out- Metal water piping system, 820.154(A),820.179(A), Connectors and couplings, door electric deicing 250.52(A)(1) 820.182(A), 830.3(B), 358.42 and snow-melting Resistance to ground of,250.56 830.154(A), Construction Specifications, equipment Separately derived systems, 830.179(A)(2) 358-111 Electric power production and 250.30(A)(7), CATV coaxial cable, Definition,358.2 distribution network 250.30(B)(2) 820.3(B),820.110 Grounding,358.60 Definition,Art. 100-1 System installation,250.53 2008 Edition NATIONAL ELECTRICAL CODE 70-795 Electrolytic cells INDEX Electrolytic cells,Art. 668 Definitions,517,2 Outdoor use,for,Table 110.20 Messenger-supported wiring, Auxiliary nonelectric connec- Elevators,dumbwaiters,escala- Overcurrent protection,240-III 396.30(C) tions,668.31 tors, moving walks, Panelboards,408.38 Metal-clad cable(Type MC)as, Cell line conductors.668.12 platform lifts,and stair- Radio equipment,810.71(A) 330.108 Cell line working zone,668.10 way chairlifts,620-X Signs, 600.8,600.42(H) Mineral-insulated metal-sheathed Cranes and hoists,668.32 Equipment approval,700.3 Switches,404.3,944.12,404.18, cable (Type MI)as, DC cell line process power Health care facilities,517.30, 450.8(C) 332.108 supply,668.11 517.30(A)(2). Types, 110.20 Motor control centers,430.96 Definitions,668.2 517.30(C)(3), 517.31 Underground,see Underground Disconnecting means,668.13 enclosures Motor terminal housings, Enclosures, 668.40 Overcursenl protection,7U0-V[ 430.12(E) Service disconnecting means, Energized Nonmetallic sheathed(Type Fixed electrical equipment, 23072(B) Definition,Art. 100-1 NMS)cable as,334.[08 Grounding,668.15 668'30 Services,230.2(A) Energized parts,.see also I-ive panelboards,408.40 Portable electrical equipment,a ui Signals,700.7 pis Parallel, 310,4(C),310.9(E) q P Signs,7(x).8 Motors,motor circuits,and con- park trailers, interior equipment, 668.20,668.21, 668.34} (rollers,430-XII Shunting eans,668.14 Sources of power,70)-Ill 552,56(B) g Energy-limited,Class 2 and Electronically actuated fuse Tests and maintenance,700.4 Class 3 control and Patient care areas,equipment in, Definition,Art. 100-11 Transfer equipment,700.6 signal circuits,725.121 517.13(B) Electronic computer/data pro- Unit equipment,ment,700.12(17) Enforcement of Code, 90.4,510?, Portable cables over 600 voles, cessing equipment,.see Wiring,700.9 400.31(C),400.32, Information technology Enamel,coating of Annex H 400.33 equipment General equipment,indoor use Entertainment devices Definition,522.2 Receptacles and cord connec- Electroplating systems,Art.669 only,300.6(A)(1) Equipment,see also specific tors,406.2(D)(1),446.3, Branch-circuit conductors,669.5 Metal boxes,314.40(A) types of 406.9 Disconnecting means,669.8 Metal cabinets,312.10(A) Approval,90.4, 110.2,Annex H Resistor and reactor Overcurrent protection,669.9 Removing for grounding con- 80.19 caseslenclosures con- Warning signs,669.7 nections,250.96(A) Cooling of, 110.13(B) netted to,470.19 Wiring methods,669.6 Rigid metal conduit, Definition,Art. 100-1 Signs and outline lighting. Electrostatic equipment,spraying 344.10(A)(4) Examination of,90.7, 110.3 600.7(A) and detearing paint, Enclosed Grounding,250-VI Sizing,250.122,310.13 516.4(E),516.10 Definition,Art. 100-1 Installation,general provisions, Solar photovoltaic systems, Elevators,dumbwaiters,escala- Enclosures,see also Hazardous Art. 110 690.45, 690.46 tors,moving walks, {classified)locations Less than 50 volts,Art.720 Switch enclosures connected to, platform lifts,and Arcing parts, 110.18 More than 600 volts,Art.490 404,12 stairway chairlifts,Art. Bonding, 50.96, 250.146 Mounting, 620 b g,see Mounting of Cabinets and cutout and control assem- Cables autout boxes, equipment blies frames connected Flexible.Table 400.4, 312.7 through 312.9. Sealable,see Sealable to,490,36,490.37 400.7(A)(4),620.21 312.11(D) equipment Tunnels, 110.54(B) Traveling,620.11(13). Circuits in,number of,90.8(BI Service Types recognized,250.118, 620.12(A),620-V Cranes,hoists,resistors, Definition,Art. 100-1 250.120,250.134 Clearances,workin g.620.5 610.3(B) Signal Equipment system Definition,Art. 100-1 Definition,620.2 Conductors,h2�lI through Definition.517? 620-IV Electrolytic cells,668.40 Equipment grounding conductor Equipotential plane,547.10, Definitions,620.2 Elevators,dumbwaiters,escala- fill and boxes, 682,33 Disconnecting ans and con- tors, moving walks, 314,16(B)(5) i= g Definition,Art. 10{}-I,547.2, trol,620-VI,620,9I(C) platform lifts,and stair- Equipment grounding conduc- tors,404.8(0) 682.2 Emergency and standby power way VIIchairlifts, 6 0.4, Escalators,see Elevators,dumb- systems,620-X 620-VIII Cable trays as,392.3(13)(1), 392(C) waiters,escalators, Essential electrical systems, Grounding,2 4(E),25 Capacitor cases conneeted to, moving walks,platform S17.32(G),517.92(G) 254.64(E),25U-IV P 0.10 460fts,and stairway Ground-fault circuit interrupters, Handhole enclosures,314.29, 4(-, , .27 lifts, 620.85 314.30 Carnivals,circuses,fairs,equip-Grounding,250.112(E),250.116, Definition, Art. 100-I ment at,525.30,5 Essential electrical systems, 250.136,620-IX Connections at outlets,250.146, health care facilities, Live parts,620.4 see also subhead d under Hazardous(classified)[ under 250.148,400.33 see Health care facilities Machine room,620-VIII Fixed outdoor electric deicing Examples(calculations),Annex D Overcurrent protection,620-VII entries for specific hat- and snow-melting Exciters Voltage limitations,620.3 ardour location involved equipment,426.44 Leads in enclosure with other High-intensity au i discharge lamp Fuel cells Stems,692.44 conductors, Wiring,620-III y' Working clearances,620.5 auxiliary equipment, Hazardous(classified)locations, 300.3(C)(2)(c) 104(A) Emergency systems,Art.700.see 410. 501.30{H},502.30(B), Overcurrent protection for, Indoor use,for,Table 1 10.20 also Legally required 503.30(B) 445.12(A) standby systems; Op- Induction and dielectric heating, Identification,250.119,40).23 Exhaust ducts,see Ducts tional standby systems 665.20 Information technology equip-P- Exits,emergency lighting for, Capacity,700.5 Industrial control panels, ment,645.15 50.32-W.517.32(B), Circuits for lighting and power, 409.100 Installation, 215.6,250.120, 517.42(A),517.42(B), 700AV,700--V Installations over 600 volts, 250.130 700.1 FPN No. 3, Circuit wiring,700-II 110.31 Intrinsically safe apparatus con- 700.12(F),700.16 Connections at services,230.82 Intrinsically safe conductors in, netted to,504.50(A) Exit signs,see Signs, exit Control,700-V 504.30(A)(2) Luminaires,410.44 70-796 NATIONAL ELECTRICAL CODE 2008 Edition INDEX Fixed electric heating equipment for pipelines and vessels Expansion joints(fittings), Farm buildings,feeder calcula- Figures,see Diagrams Marking,760.179 250.98,300.7(B), lions,220.102,see also Films,motion picture,see also Overcurrent protection,Chap. 352.44,355.44,366.44, Agricultural buildings Projector rooms, motion 9,Tables 12(A)and 368.238.368,244, Fault protection device picture 12(B) 424.44(0),424.98(C), Definition. 830.2 Storage vaults,530-V Power sources,760.121 424,99(0)(1),426.20(E), Fault tolerant external control Viewing,cutting,patching tables Wiring methods and materials 426.21(C),426.22(D), circuits,695.14(A) 530-IV Load side,760,130 427.16 Definition,695.2 Fine Print Notes(FPNs),manda- Supply side,760.127 Explanatory material FPN, Feeder assembly,mobile homes, tory rules,permissive Fire detectors,line-type, 90.5(C) 550.10(A) rules,and explanatory 760.179(J) Explosionproor apparatus,500.2, Definitions.550.2 material,90.5 Fire um s Art.695, 500.7(A),502.5, Feeders,Art. 215,Art. 220 Finish rating P p ' Connection at services, 505.16(13)(2) Busways,368.17 Definition,3 62.10 FPN Definition,Art. 100-I Calculation of loads,see Loads Fire alarms,see Alarms;Alarm 230.72(A)Ex., Explosive atmospheres,gases, Critical operations power sys- systems,health care 230.82(5), 230.94 Ex.4 liquids,dusts,ignitible tems,708-I1 facilities;Fire alarm Continuity of power,695.4 fibers/flyin gs,and lint, Definition,Art. 1004 systems Control wiring,695.14 see Hazardous(classi- Emergency systems,700.9(D) Fire alarm systems,Art.760 Definitions,695.2 tied)locations Equipment grounding conduc- Abandoned cables,760.25 Emergency power supply, Exposed,see also Enclosures tors,250.122(G) Definition,760.2 Art.700 Conductive surfaces Farm buildings,far,220.102 Access to electrical equipment, Equipment location,695.12 Definition,517.2 Ground-fault circuit interrupters, 760.21 Grounding,250.I12(L), Definition,770.2,820.2.830.2 with, 215.9 Circuits extending beyond one 250.112(M) Hazardous(classified)locations, Grounding means, 215.6 building,760.32 Listing,695.10,695.11 501.25,502.25,503.25, Hoistways and machine rooms, Connections at services, Motor,overcurrent protection, 505.19 620,37(C) 230.82(5),230.94 Ex.4 430.31 FPN Live parts, 110.26 Identification, 225.37,230.2(1;) Critical operations power sys- On-site standby generator, Definition.Art, 100-I Kitchen equipment,commercial, tems,708.14 695.3(B),695.3(B)(1), Luminaire parts 410.42,410.44 220.56 Definitions,760.2 695.6(D)Ex. 2 Structural metal, 1 roundin , Loads,see Loads,feeders Grounding,250.112( ) g g Definition,695.2 250.52(A)(2) Mobile homes and parks, Health care facilities,517-V1 Power sources to electric motor- Wiring methods 550.10(A),5504II Identification,760.30 driven,695.3 Definition,Art. ]00-I Motion picture studios, Installation,760.32 Power wiring,695.6 Extension cord sets 530.18(B) Location,760.3 Remote-control circuits, On construction sites,590.6(A) Motors,430-11 Mechanical execution of work, 430.72(B)Ex. I and(13)(2) Outside,see Outside branch cir- 760.24 Service equipment overcurrent Overcurrent protection.240.5 cuits and feeders Nonpower-limited circuits, protection,230.90(A) Extensions Overcurrent protection 760-II Ex 4 Auxiliary gutters,366.12 Accessibility, 240.24(A) Cable marking,760.176, Cellular metal floor raceways. Motor,430-V Table 760.176(0) Services,230.2{A)(1) 374.11 Pools,permanently installed, Conductors,760.49 Supervised connection,695.4(B) Transformers,695.5 680.25 Different circuits in same Flat cable assemblies,322.40(D) drop,695.7 Lighting systems operating at 30 Recreational vehicle sites, raceway,etc.,760.48 Voltage p volts or less,conductors 551.73,551.80 Number of conductors in Fire spread for,411.4(A) Restaurants,220.88 raceway,etc.,and derat- Prevention of,wiring methods, Nonmetallic,see Nonmetallic Services,220-III ing, 760.51 300.21,725.3(B), extensions Stage switchboard,520.27 Listing,760.176 760.3(A),770.26, Surface,boxes and fittings. Taps,240.21(B),240.92(B), Marking,760.176 800.26,820.26,830.26 314.22 430.28 Multiconductor cable,760.53 Fire-stopped partitions,300.21; Surface metal raceways, Television studio sets,530.19 Overcurrent protection, see also Firewalls 386.10(4) Feed-through conductors, 760.43,760.45 Firewalls,wiring through,300.21 Wireways,376.70.378.10(4), 312.11(D) Power source requirements, Fittings,Art.314;see also Wiring 378.70 Ferrous metals,see also Rigid 760.41 methods,Types and Externally operable,see Oper- metal conduit(Type Requirements,760.35(A) materials able,externally RMC) Wiring method,760.46, Conduit bodies,314.16 Induced currents in enclosures 760.53(A) Definition,Art. 100-1 or raceways,300.20 Power-limited circuits,760-1II Expansion,see Expansion joints Protection from corrosion, Cable markings,760.179 (fitting) -F- 300.6(A) Cable substitutions, Insulation,300.4(G) Faceplates Festoon lighting 760.154(D),Table Integrated gas spacer cable, Grounding,404.9(B),406.5(B), Conductor size,225.6(B) 760.154(D) 326.40 550.15(D) Definition,Art, 100-I Circuit integrity cable, Material,404.9(C).406,5 Portable stage equipment, 760.179(H) Fixed electric heating equipment Minimum thicknesses for, 520.65 Circuit markings,760.124 for pipelines and ves- 404.9(C),406.5 Festoon wiring,portable stage Conductors sels,Art.427 Mobile homes,550.15(D) equipment,520.65 Separation,760.136 Continuous load,427.4 Mounting surfaces,against, Fiber bushings,AC cable ends, Size,760.142 Control and protection 427-VII 404A(A),404.10(B), 320.40 Support,760.143 Controls,427.56 406.4.406.8(E) Fibers/flyings,lint,ignitible,Art. Installation,760.133,760.139 Disconnecting means,427.55 Fairs,see Carnivals,circuses, 503,Art.506;see also Line-type fire detectors, Overcurrent protection, fairs,and similar events Hazardous(classified) 760.145.760.179(J) 427.57 Fans,ceiling,.tee Ceiling fans locations Listing,760.179 Definitions,427.2 2008 Edition NATIONAL ELECTRICAL CODE 70--.797 Fixed electric heating equipment for pipelines and vessels INDEX Impedance heating,4274V Limit controls,424.64 Ground fault,210.8(A)(3) Construction,324-III Grounding,427.29 Electrode-type boilers,424-VIII Ex..426.28 Conductor identification, Induced currents,427.28 Installation,424-11 Thermal,426.12 324.120(B) Isolation transformer,427.26 Location Resistance heating elements. Insulation,324.112 Personnel protection,427.25 Exposed to physical dam- 426-III Markings,324.1201A) Secondary conductor sizing, age,424.12(A) Embedded,426.20 Receptacles and housings, 427.30 Wet areas,424.12(B) Exposed,426.21 324.42(B) Voltage limitations,427.27 Spacing,combustible materi- Skin effect heating,426-V Shields, 324.100(B) Induction heating,427-V als,424.13 Conductor am aeit ,426.40 F Y Definitions, 324.2 Induced current.427.37 Special permission,424.10 Pull boxes,426.41 Transition assemblies, Personnel protection.427.36 Supply conductors,424.11 Single conductor in enclo- 324.56(B) Scope,427.35 Listed,424.6 sure,426.42 Installation,427-11 22 220.83 S ecial Definitions,324.2 Load._..0.51,_20.R_fC), P permission,426.14 Installation,32441 General,427.10 Marking,424--IV Thermostat;for,426.51 Alterations,324.56(A) Identification,427.13 Boilers,424,86 Use of.426.11 Boxes and fittings,324,40 Thermal protection,427.12 Cables,424.35 Fixtures,see Luminaires Cable connections and insu- Use,427.11 Heating elements,424.29 Fixture wires,Art.402 toting ends,324.40i%u Resistance heating elements, Nameplates,220.82(C), Ampacities,402.5 Connections to other systems, 427-I11 424.28 Grounded conductor,identifica- 324.40{D) Definition,427.2 Radiant heating panels and tion,402.8 Electrical connections.427.19 Markin 402.9 Crossings,324.18 heating panel sets, g� Equipment protection.427.22 424.92 Minimum size,402.6 Heated floors,324.10(F) Expansion and contraction, Number in conduits or tubing, shield connectors, ry Qvercurrent protection for, g' 324.40(E) 427.16 424.22,424.72,424.82 402.7 Flexural capability,427,17 Radiant heating panels and heat- Overcurrent protection,240.5, Receptacles,324.42 Grounded conductive cover- 402,)2 Shields,324.40(C), 324.40(E) t" 42 in 427.23 42 panel sees,424-IX, Supports.324.30 7.23(B) Types,402.3 Marking,427.20 Clearances, wiring Uses not permitted,402.11 System height,324.10(G)Not in direct contact,427.15 Ceilings, 124.94 Uses permitted,402.10 Polarization,324.40(B) Power supply leads,427.[8 Walls,424.95 Flame spread,see Fire spread Systems alterations,324.56(A) Secured,427.11 Connection,424.96 Flammable anesthetics see also Uses not permitted,324.12 Skin effect heating,427--VI Definitions,424.91 Anesthetizing locations Uses permitted,324.10 Conductor ampacity,427.45 Definition,517.2 Flatirons Grounding,427.48 Installation,424.93,4_4.98, Flammable gases,see Hazardous Cords,422.43(A) Pull boxes,427.46 Markings,4 (classified)locations Signals,422.42 Markings,424.92 g Single conductor in enclo- Flammable-liquid produced va- Stands for,422.45 sure,427.47 Nunheating leads,boilers,424 pors,see Hazardous Temperature-limiting means, Fixed electric space-heating Resistance-type boilers,424-VII � P g Fixed equipment,grounding, (classified)fixations 422.42,4..2.46 equipment,Art.424 Flammable liquids,see Hazardous Flexible cords,see Cords, flexible Branch circuits for,424.3 250.110,250.112, (classified)locations Flexible metal conduit 250.116, 250.134, (� Cables,424-V Flashers,time switches,etc., FMC),Art.348 Area restrictions,424.38 250.136,250.190, 404.5,600.6(B) 517.13 Bends,348.24,348.26 Clearances,wiring Flat cable assemblies(Type FC), Couplings,and connectors, Fixed outdoor electric deicing Ceilings,424.36 Art. 322 348.42 and snow-melting Other objects,openings, Saxes and fittings,322.40 Definition, 348.2 424.39 equipment,Art.426 Branch-circuit ratin 322.10(1 J Branch circuits for, g' Grounding and bending,348.60 Construction,424.34 Conductor insulations for. Installation,348-II Finished ceilings,424.42 210.19(A)(4)Ex.I(e) 322.112 Connections,426.24 Installation Conductor size,322.104 Liquidlight,see Liquidtight flex- In concrete or poured ma- Continuous load,426.4 Construction,322-1II ible metal conduit sonry Mixers,424.44 Control and protection,426-V1 Dead ends,322.40(A) Listing,348.6 Nunheating leads,424.43 Cord-and-plug-conaected, Definition,322.2 Maximum number of conductors Marking,424.35 426.50(B),426.54 Extensions from,322.40(D) and fixture wires in. Splices,424.40,424.41(Df Definitions,426.2 Fitting.for,322.40(C) Tables C3 and C3A Tests and inspections,424.45 Disconnecting means,426.50 Identification grounded conduc- Number of conductors,348.22 Control and protection,424-111 General,426.10 tor,322.120(B) Securing and supporting,348.30 Controllers,424.20(A) Ground-fault circuit interrupters, Luminaire hangers,322.40(B) Size,348,20 Disconnecting means.424.19 210.8{A)(3)Ex. Marking,322.120 Splices and taps. 348.56 through 424 21,424.65 Grounding,426.22(A),426 27, Number of conductors in, Trimming,348.28 Indicating,424.21 42634.426.44 322.100 Uses not permitted,348.12 Overcurrent protection, Identification of,426.13 Size of conductors in,322.104 Uses permitted,348.10 424.22,424.72,424.82 Impedance heating.426-IV Splices,322.56 Flexible metallic tubing(Type Duct heaters,424-V1 Induced currents,426.33 Supports for,322.30 FMT),Art.360 Airflow,424.59 Isolation transformer,426.31 Terminal block identification, Bends,360.24 Condensation,424.62 Personnel protection,426.30 322,120(C) Boxes and fittings,360.40 Disconnecting means,loca- Voltage limitations,426.32 Uses not permitted,322.12 Construction specifications, tion,424.65 Installation,426-11 Uses permitted,322.10 360-III Elevated inlet temperature. Marking,426.25 Flat conductor cable(Type Definition,360.2 424.60 Nunheating leads, installation(if, FCC),Art.324 Grounding,360.60 Fan circuit interlock,424.63 426.22,426.23 Branch-circuit rating,324.101BJ Installation,360-II Identification,424.58 Protection Cable connections and ends, Listing,360.6 Installation,424.61,424.66 Corrosion,426.26.426.43 324.40(A) Marking,360.120 70-798 NATIONAL ELECTR[CAL CODE 2009 Edition INDEX Generators Number of conductors, 360.22 Connection to other circuits, Motor branch circuit protection, Number and sizes of,in race- Sizes,360.20 692-VII 430-IV ways,300.17 Splices and taps, 360.56 Identified interactive equip- Motor overload protection, Supporting of conductors in Uses not permitted,360.12 ment,692.60 430-III vertical raceways, Uses permitted,360.10 Loss of interactive system Multiple,see Multiple fuses 300.19 Floating buildings,Art.553 power,692,62 Over 600 volts,490.21(B) Exhaust and ventilating duets, Bonding of noncurrent-carrying Output characteristics,692.61 In parallel,not permitted, 240.8, wiring,300.22 metal parts,553.11 Point of connection,692.65 404.17 Expansion joints,raceways, Definition,553.2 Transfer switch,692.59 Plug,Edison-base type, 240-V 300,7(B) Feeder conductors,553.6 Unbalanced interconnection, Potential (voltage)transformers, Free length of wire at outlets, Grounding,553-1I1 692.64 450.3(C) junction and switch Insulated neutral,553.9 Definitions,692.2 Ratings,240.6 points,300.14 Service conductors,553.5 Disconnecting means,692-111 Service equipment,230.95(B) Induced currents in ferrous Service equipment location, All conductors,692.13 Services over 600 volts, 230.208 metal enclosures,300.20 553.4 Provisions of,692.14 Type S.240.53,240.54 Mechanical and electrical conti- Services and feeders, installa- Switch or circuit breaker, Future expansion and conve- nuity,conductors,race- tion,553.7 692.17 nience,90.8(A) Floor pockets,520.46 Emergency systems,source of ways,cables,300.10. Floors,receptacles,210.52(A)(3), power for,700.12(E) 300.12,300.13 250.146(C),314.27(C) Grounding,692-V Over 600 volts, I I0-III,300-II, Flue damper control,see Damp- Equipment grounding con- -G- Art.490 ers(flue),control ductor,692.44,692.45 Gages(AWG),conductors, 110.6 Protection against Fluorescent luminaires,410-XIII, Grounding electrode system. Garages,commercial,Art.511 Corrosion,300.6 410-XIV 692,47 Battery charging equipment, Physical damage,300.4 Autotransformers in ballasts, System grounding,692.41 511.10(A) Raceway installations,300.18 410.138 Installation,692.4 Classification of locations, 511.3 Raceways and cables with other Auxiliary equipment,remote Marking,692-VI Definitions,Art. 100-1, 511.2 systems,300.8 from,410.137 Fuel cell power sources, Electric vehicle charging, Raceways and fittings,metric Ballast protection required, 692.53 511.10(B) designator and trade 410.130(E) Fuel shutoff,692.54 Elevators,dumbwaiters,escala- size,300.1(C) Circuit breakers used to switch, Stored energy,692,56 tors,moving walks,in, Raceways as a means of sup. 240.83(D) Overcurrent protection, 620.38 port,300.11(B) Connection of,410.24, 692.8(B),692.9 Equipment,511.4,511.7 Raceways exposed to different 410.62(C) Over 600 volts,692-VIII Ground-fault circuit-interrupter temperatures,300,7 Disconnecting means, General,692.80 protection,511.12 Raceways in wet locations 410.130(6) Stand-alone system,692,10 Grounding,250.112(F) above grade,300.9 Load calculations Standby systems, legally re- Grounding and bonding, 511.16 Sealing,raceways,change in Ampere ratings,ballasts, quired,701.11(F) Locations,511.4 temperature,300.7(A) 220.18(B) Wiring methods,692-IV Sealing,511.9 Securing and supporting,300.11 Branch circuits,210.23 Wiring systems,692.31 Special equipment,511.10 Spread of fire or products of Raceways,410.64 Full-load current motors Ventilation,511.3(C) combustion,300.21 Snap switches for 404.14(A)(1), Alternating current Wiring,511.4,511.7 Temperature limitations,310.10 404.14(B)(2) Single-phase,Table 430.248 Gases,see Hazardous(classified) Through studs,joists,rafters, Surface-mounted or recessed, Three-phase,Table 430.250 locations 300.4 410.16(A)(2),410.16(C) Two-phase,Table 430.249 Gasoline bulk storage plants,see Underground installations, Thermal protection,410,130(E) Direct current,Table 430.247 Bulk storage plants; 300.5,300.50 Fluoroscopic equipment,see Furnaces see Heating equipment, Hazardous(classified) Voltage limitations,300.2 X-ray equipment central locations Wiring in ducts,plenums,air- Flyings,ignitible,see Fuseholders Gasoline dispensing and service FiberslHyings, lint, Cartridge fuses,240-VI stations,see Motor fuel handling spaces,300.22 Generators, ignitible Over 600 volts,490.21(B) dispensing facilities Art. Footlights,theaters,520.43 Plug fuses,240-V Gas pipe Bushings,445.116 6 Definition,520.2 Rating,motor controllers. As grounding electrode, Conductor,rtions y of,445.13 Disappearing,520.43(0) 430.90 250.52(B)(1) Critical operations power sys- Formal interpretations,90.6 Type S,240.53,240.54 General care areas,517.18 tems,585.20(F) Forming shells,underwater pool Fuses,Art.240,see also Hazard- Definition,517.2 Disconnecting means,445.18 luminaires,680.23(B), ous (classified)locations General provisions,installation Emergency systems,700.12(B) 680.24(B), Cartridge,see Cartridge fuses of wiring and equip- Essential electrical systems,task 680.26(B)(4), Communications circuits,pro- ment,Art. 110 illumination,517.32(E), 680.27(A)(3) tectors for, 800.90(A)(2) General requirements for wiring 517.32(F),517.42(F) Definition,680.2 Definition,over 600 volts,Art. methods,Art.300.see Grounding,250.34,250.35, Fountains,see also Swimming 10041 also Wiring methods 250.112 pools,fountains,and Disconnecting means,240.40 Boxes,conduit bodies,or fit- Guards for attendants,445.15 similar installations Electronically actuated tings-where required, Health care facilities,517.30, Drinking,422.52 Definition,Art. 100-11 300.15 517.35,517.44 FPN,explanatory material, Enclosures,240-111 Changing raceway or cable to Interconnected electric power 90.5(C) Generators,constant-voltage, open wiring,300,16 production sources, Frame 445.12(A) Conductors,300.3 705-III Definition,551.2 Group installation of motors, Different systems,300.3(C) Location,445.10 Fuel cell systems,Art.692 430.53(C) Installation with other sys- Marking,445.11 Circuit requirements,692-11 Location in circuit,240.21 tems,300.8 Multiple loads,supplying, Circuit sizing, 692.8 Location on premises,240.24 Insulated fittings,300.4(0) 445.19 2008 Edition NATIONAL ELECTRICAL CODE 70-799 Generators INDEX Overcurrent protection,445.12 Pools and tubs for therapeutic Audio signal processing,ampli- More than 600 volts between Portable,250.34 use,680.62(A), fication,and reproduc- conductors,300.40 Protection of live parts,445.14 680.62(E) tion equipment,640.7 Motion picture studios,530.20 Recreational vehicles,551.30 Receptacles,210.8 Bonding,see Bonding Motors and controllers,250-VI, Standby systems,Art.701,702 Bathrooms,in dwelling units, Busways,368.60 430.12(E),430.96, Fire pump,on-site, 210.8(A)(1) Over 600 volts,368.260 430-XIII 695.3(B)(I), Bathrooms in other than Cablebus,370.9 Naturally and artificially made 695.3(B)(2), dwelling units, Capacitors,460.10,460.27 bodies of water,electri- 695.6(D)Ex. 2 210.8(B)(1) CATV systems, 620.93,820-IV cal equipment for, Terminal housings,445.17 Boathouses,555.19(B)(1) Circuits,250-1 682-III Goosenecks,service cables, Construction sites,at,590.6 Less than 50 volts,250.20(A) Nonelectrical equipment, 230.54 Fountains,680.57(B),680.58 Clothes dryers,250.114(3), 250.116 Grooves,cables and raceways Garages, in dwelling units, 250.140 Organs,650.5 installed in,300.4(F) 210.8(A)(2) Clothes washers,250.114 Over 600 volts,300.40,490.36,Ground Health care facilities, Communications systems, 490.37,490.74 Definition,Art. 1004 517.20(A).517.21 800.93,800.106(A), Over 1000 volts,250-X Panelbaards,408.40,517.19(D) Voltage to Kitchens in dwelling units, 800-IV Patient care areas,517.13, Definition,Art. 100-1 210.8(A)(6) Continuity,250.96 517.19(C) Ground clamps,250.10, 250.70 Marinas and boatyards, Control,radio equipment, Portable equipment, 250.114 Grounded 555.19(B)(1) 810.71(B) Radio and television,810.15, Definition,Art. 100-I Mobile homes,550.13(B), Control panels,409.60 810.21,810.58, Effectively 550.32(E) Cranes and hoists,610-VII 810.71(B) CATV system,820.100, Outdoors,dwelling units, DC systems,250.162,250.164 Ranges and similar appliances, 820-IV 210.8(A)(3) Deicing,snow-melting systems, 250.140 Communication system, Park trailers,552.41(C) 42622(A) 42627, Receptacles,210.7,250.146, 800-1V Pools,680.5,680.6, Solidly 680.22(4){4), 426.34,426.44 250.148,406.3,5I7.13, Dishwashers,250.114 517.19(G) Definition,Art. 100-1 680.22(B),680.32, Electrode system,250-1I1 Recreational vehicles,551.54, Grounded conductor,see Neutral 680.62(E) Elevators,250.112(E),250.1 16, 551.55,551.75,551.76 [ors,Grounded;Neutral Recreational vehicles, 250136,6620-IX Refrigerators,250.114 . Ground-fault circuit interrupters 551.40(C),551.41(C) Sensitive electronic equipment. Accessory buildings,dwelling Replacement,406.3(D)(2) Enclosures,250.64(D), 647.6 units,210.8(A)(2) Required,210.8 250.64(E),250-IV q Separate buildings, 250.32 Aircraft hangars,513.12 Rooftops in other than dwell- Equipment,cord-and-plug- Separately derived systems, Appliances ing units,210.8(B) connected,250.114 250.20(D), 250.21{A), Drinking fountains,422.51 Sensitive electronic equip- Fire alarm systems,250.112(1) 250.30 High-pressure spray washers. ment,647.7(A) Fixed equipment,250.110, Signs and outline lighting, 422.49 Spas and hot tubs,680.43(A), 250.112,250.134. 600.7(A),600.24(8) Vending machines,422.51 680.44 317.13 Spas and tubs.680.6,680.7(B), Basements,dwelling units,un- Wet bar sinks, 210.8(A)(7) Fixtures,lampholders,etc., 680.43(F) finished,2I0.8(A)(5) Swimming pools,see Swimming 410.155(B),410-V Surge arresters,280.25 Bathtubs,hydromassage,680.71 pools,fountains,and Fountains,680.54,680.55 Surge protective devices,285.28 Carnivals,circuses,fairs, and similar installations Freezers,250.114 Swimming pools,680.6, similar events,525.23 Ground-fault protection Fuel cell systems,692--V 680.7(B),680.23(B)(3) Definition,Art. 100-1 Connections at services,230.82 Generators,250.34,250.112 and(17)(2),680,24(D). Electrically operated pool cov- Deicing and snow-melting Hazardous(classified)locations, 680.24(F),680.25(6) ers,680.27(B)(2) equipment,426.28 501.30,502.30,503.30, Switchboards,250.112(A), Electric signs,portable or mo- Emergency systems,not re- 505 25,506.25 408.22 bile.600.10(C)(2) quired,700.26 Health care facilities,517.13, Switches,404.9(6),404.12 Electrified truck parking space Equipment, 215.10,240.13 517.19 Systems, 250-1,250-11 supply equipment, Definition,Art. 100-1 High density polyethylene con- Theaters and similar locations, 626.24(D) Health care facilities,517.17 duit,353.60 520.81 Elevators,dumbwaiters,escala- Personnel,see Ground-fault cir- Induction and dielectric heating Tools,motor operated,250.114 tors,moving walks, cuit interruplers equipment,665-I1 Transformers,450.5,450.6{C), platform lifts,and stair- Pipeline heaters,427.22 Information technology equip- 450.10 way chairlifts,620.85 Service disconnecting means, men[.645.15 X-ray equipment,517.78,660-IV Fixed electric space-heating 230.95 Instrument transformers,relays, Grounding conductors,250-111, equipment cables, Solar photovoltaic systems, etc.,250-X 250-VI;see also Equip- 424.44(G) 690.5 Intrinsically safe systems, ment grounding conduc- Fountains,680.51(A) Grounding,Art.250;see also 504,50 tors;Grounding elec- Garages,commercial,5 11.12 subhead under entries Lightning surge arresters,280.25 trode conductors Garages,dwelling units, for specific wiring and Metal boxes,314.4,314.40(D) Communications circuits, 210.8(A)(2) equipment Metal enclosures for conductors, 800.100 Naturally and artificially made AC systems,250.20,250.24, 250.80,250.86 CATV coaxial cable, bodies of water,electri- 250.26 Metal faceplates,404,9(B), 820.100(A) cal equipment for. Air-conditioning units, 250.114 406_5(B) Network-powered broadband 682.15 Anesthetizing locations,517.62 Metal siding,250.116 FPN communications cable, Permitted uses,210.8,215.9 Antenna, 810.15, 810.21, Methods, 250-VII 830.100(A) Personnel,protection For,426.32 810.58,810.71(B) Mobile homes,550.16 Radio and television equip- Pipeline heating,427.27 Appliances,250.114 ment,810.21,810.58 70-800 NATIONAL ELECTRICAL CODE 2008 Edition INDEX Hazardous (classified) locations Communications systems, Motion picture studios,530.15, Approval for class and prop- Nonincendive component, 800.100(A) 530.62 erties,500.8(B) 500.7(H) Definition,Art. 100-I Motors and motor controllers, Fiber optic cable assembly, Nonincendive equipment, Earth as,250.4(A)(5),250.54 430.243,430-XII 500.8(F) 500.7(G) Enclosures,250-1V Over 600 volts, 110.34,590.7. Marking,500.8(C) Oil immersion,500.7(1) Identification,multiconductor see also Protection, Suitability,500.8(A) Receptacles and attachment cable, 250.119 Physical damage Temperature marking, plugs,501.145 Installation,250.64,250.120 Portable cables,400.31(B). 500.8(D) Sealing,501.15 Material,250.62 400.32 Threading,500.8(E) Signaling,alarm,remote-control, Objectionable current aver, Transformers,450.8 Explosion proof apparatus, and communications 250,6 Ventilation openings, 110.78 500.7(A) systems,501.150 Optical fiber cables,770.100(A) X-ray installations,517.78, Fibers/flyings,lint,highly com- Surge protection,501.35 Sizes, 250.122 660-IV bustible material,Arts. Switches, 50 1,115 Grounding electrode conductors, Guest rooms or suites 503 and 506 Transformers and capacitors, see also Electrodes. Branch-circuit devices, Flammable liquids,Arts. 500 501.100 grounding 240.24(B) and 501 Utilization equipment,501.135 Connection to electrodes, 250-1, Branch-circuit voltages, Garages,commercial,511.3, Wiring methods,501.10 250.24(D),250-III 210.6(A) 511,4 Zone 0, 1,and 2 locations,see Definition.Art. 100-1 Cooking equipment,branch cir- Gases, flammable,Arts.500 Hazardous(classified) Installation,250.64 cuits for,210.18 and 501 locations,Class 1,Zone Intersystem,connecting,250.94 Definition, Art. 100-1 Gasoline service stations,see 0, 1,and 2 locations Material,250.62,250.118 Outlets, 210.60,210.70(B), Motor fuel dispensing Zone equipment,501.5 Separately derived systems, 220,14(J) facilities Hazardous(classified)locations, 250.30 Overcurrent devices,240.24(E) General,500.4 Class 1,Zone 0,1,and Sizing,250.30(A)(4)(a),250.66, Gutters,auxiliary,see Auxiliary Group classifications,500.6 2 locations,Art.505 250.166 gutters Hoists,503.155 Bonding,505.25(A) Solar photovoltaic systems, Inhalation anesthetizing loca- Class I,Zone 0, 1,and 2 group 690.47 through 690.49 tions,see Anesthetizing classifications,505.6(A) Grounding electrodes,see Elec- -H_ locations Classification of locations,505.5 Intrinsic safety.500.7(E).see trodes,grounding Hallways,outlets,210.52(H) also Intrinsically safe Class I,zone 0,505.5(B)(1) Grounding point Handlam s portable,410.82 Class 1,Zone 1,505.5(B)(2) Patient equipment P 'P systems Class 1,Zone 2,505.5(B)(3) Hangars,aircraft,see Aircraft bighting systems,less than 30 Defin hangars volts,411.7 Definition. 517.2 Conductors and conductor insu- Reference Hazard current lator,505.18 � Material groups,500.6 Definition,517.2 Definition,517.2 Protection techniques,500.7 Definitions,505.2 Grounding-type attachment Hazardous areas,see Hazardous Documentation,505.4(A) Specific occupancies,Art. S l0 plugs,406.9 (classified)locations Spray application,dipping and Equipment construction,505.9 Ground ring,250.52(A)(4), Hazardous atmospheres,Art.500 Class I temperature,505.9(D) p � coating processes,516.3 Fiber o y 250,53(F),250.66(C), Class I locations,500.5(B) Vapors,flammable,Art.500, optic cable assembly, 250.166(E) Class II locations,500.5(C) 501 505.9(F) Grouping,switches,circuit Class III locations,500.5(D) Hazardous(classified)locations, Listing,505.9(B) breakers,404.8.see Groups A through G.500.6 Class I,500.5(8), Marking,505.9(C) also Accessible Specific occupancies,Art.510 500.6(A),Art,501; .see Suitability,505.9(A) Grouping of disconnects,230.72 Hazardous(classified)locations, also Hazardous(classi- Threading,505.9(E) Group installation,motors,see Classes I,II,and III, lied)locations,Classes Equipment for use in,505.20 Motors,grouped Divisions 1 and 2,Art. I,II,and III,Divisions Exposed parts,505.19 Guarded 500.;see also Hazard- ( and 2; Hazardous Flexible cords,505.17 Definition, Art. 100-I ous(classified)loca- (classified)locations, General,505.4 Guarding,guards,see also Enclo- tions,Class I,Zone 0, Class I,Zone 0, 1,and Grounding,505.25 sures; Live parts 1,and 2 locations 2 locations Material groups.505.6 Circuit breaker handles, Aircraft hangars,513.3 Bonding,501.30(A),504.60 Protection techniques. 505.8 240.41(B) Anesthetizing locations, Circuit breakers,501,115 Combustible gas detection Construction sites,590.7 517.60(A),517.61 Control transformers and resis- system,505.8(K) Elevators,dumbwaiters,escala- Bulk storage plants,515.3 tors,501.105(B)(2). Definition,505.2 tors,moving walks, Class 1,see Hazardous(classi- 501.120 Encapsulation,505.8(G) 620,71 fied) locations,Class I Cranes and hoists,610.3(A)(1) though 505.8(I) Generators,445.15 Class 1,Zone 0, 1,and 2,see Drainage of equipment, Definition,505.2 Handlamps,portable,410.82(B) Hazardous(classified) 501.15(F) Flameproof,505,8(A) Induction and dielectric heating locations,Class 1,Zone Exposed parts,501.25 Definition,505.2 equipment,665-II 0, 1,and 2 locations Flexible cords,501.140 Increased safety,505.8(F), Intrinsically safe apparatus, Class 11,see Hazardous(classi- Fuses,501.115 505.22 cable shields far, fled)locations.Class 11 Grounding,501.30 Definition,505.2 504.50(B) Class III,see Hazardous(classi- Hermetically sealed,500,7(1) Intrinsic safety,505.8(C) Lamps,theaters,dressing rooms, fied)locations,Class III Induction and dielectric healing Definition,505.2 etc.,520.44(A)(3). Combustible gas detection equipment,665.4 Oil immersion,505.8(E) 520.47,520.65,520.72 system,500.7(K) Luminaires,501.130 Definition,505.2 Live parts Definitions,500.2 Meters,instruments,and relays, Powder filling,505.8(J) General, 110.27 Dust ignitionproof,500.7(B) 501.105 Definition,505.2 On stage switchboards. Dusts,explosive,Art.502 Motor controllers,501.115 Purged and pressurized, 520.22 Dusttight,500.7(C) Motors and generators,501.120 505.8(B) In theaters,520.7 Equipment,500.8 Nonincendive circuit,500.7(F) Definition,505.2 2008 Edition NATIONAL FLFCTRICAL CODE 70-801 Hazardous (classified) locations INDEX Type of protection"n,' Switches,503.115 Clinics,medical and dental Rating of supply conductors, 505.8(D) Transformers and capacitors, offices,and other health 517.73 Definition,505.2 503.100 care facilities,517.45 Transformers and capacitors, Reference standards,505.4(B) Utilization equipment, 503.135 Connections 517.76 Sealing and drainage,505.16 Ventilation piping.503.128 Alternate power source, Heater cords,see Cords,heater Special precaution,505.7 Wiring methods,503.10 517.34 Heat generating equipment,see Wiring methods,505.15 Zone 20,21,and 22 locations Critical branch.517.43 Induction and dielectric Hazardous(classified)locations, for flammable dusts. Life safety branch,517.42 heating equipment Class II,500.5(C),Art, fiberslflyings,Art. 506 Critical branch,517.33, Heating,see aLso Heating systems; 502;see also Hazardous Hazardous(classified)locations, 517.43 Induction and dielectric (classified)locations, specific,Art. 510 Definition,517.2 heating equipment Classes I,II,and III, Hazardous(classified)locations, Emergency system,517,31 Dielectric Divisions I and 2 Zone 20,21,and 22, Essential electrical systems, Definition, 665.2 Bonding,502.30(A) Art,506 517.41 Induction Circuit breakers,502.115 Bonding,506.25(A) Hospitals,517.30 Definition,665.2 Control transformers and Classification of locations,506,5 Life safety branch.517,32 Heating appliances,Art.422;.see resistors,501.120 Definitions,506.2 Nursing homes and limited also Infrared lamp in- Cranes and hoists,610.3(Al(21 Documentation,506.4(A) care facilities.517.40 dustrial heating appli- Exposed parts.502.25 Equipment installation,506.20 Power sources,517.35, ances;Water heaters Flexible cords,502.140 Manufacturer's instructions, 517.44 Heating cables,Art.424 Fuses,502.115 506.20(D) General,517-1 Heating elements Grounding,50230 Temperature,506.20(E) Inhalation anesthetizing loca- Marking,422.61 Luminaires,502.130 Equipment requirements,506.9 (ions,517-IV Resistance,see Fixed electric Motor controllers,502.115 Listing,506.9(B) Classification,517.60 heating equipment for Motors and generators, 502.125 Marking,506.9(C) Grounded power systems in pipelines and vessels Multiwire branch circuits, anesthetizing locations, Heating equipment Suitability.506.9{A) 502.40 517.63 Central,422.12 Temperature.506.9(D) Receptacles and attachment Threading,506.9(E) Grounding,517,62 Definition,665.2 plugs,502.145 Flexible cords,506.17 Line isolation monitor, Fixed,see Fixed electric heating Sealing,502.15 General,506.4 517.160(B) equipment for pipelines Signaling,alarm,remote-control, Grounding,506.25 Low-voltage equipment and and vessels; Fixed elec- and communications Multiwire branch circuits, instruments,517.64 trio space-heating equip- systems,meters,instru- 50621 Wiring and equipment, ment; Fixed outdoor ments.and relays. Protection techniques.506.8 517.61,517.160 electric deicing and 502.150 Definitions,506.2 Isolated power systems, snow-melting equipment Surge protection,502.35 Dust ignitionpro of,506.8(A) 517.19(F).517-VII Induction and dielectric,see Switches,502.115 Wiring and protection,517-II Induction and dielectric Transformers and capacitors. Dusttighl,506.8(D) Applicability,517.10 heating equipment 502.100 Encapsulation,506.8(E), Critical care areas,517.19 Outside,550.20(B) Utilization equipment.502.13 506.8(F) 5 Fixed electrical equipment Receptacle outlets,214.63 Ventilatin g piping, 502.128 Enclosure,506.8(1) and grounding of rece P- Swimming pools,see Swimming Wiring methods,502.10 Intrinsic safety,506.RIC), tacles,517.13 pools.fountains,and Zane 20,21,and 22 location~ [slonin endive)circuit and General care areas,517.18 similar installations for flammable dusts, General Heating panels and healing panel ,s fiberslft in Art.506 equipment,506.8(G), y g 506 8(H) installation/construction sets,radiant,see Fixed Hazardous(classified)locations, criteria,517.11 electric space-heating Class III,500.5(D).Art. Pressurization,506.8(B 1, Ground-fault circuit- equipment,Radiant 503;see also Hazardous 506.8(J) interrupter protection, heating panels and heat- (classified) locations, Reference standards,506.4(B) 517.20(A1,517.21 ing panel sets Classes 1,II,and 111, Sealing,506.16 Ground-fault protection, Heating systems Divisions I and 2 Special precautions,506.6 517.17 Impedance Bonding,503.30(A) Wiring methods,506.15 Grounding,517.13 Definition,427.2 Circuit breakers. 503.115 Headers Panelboard banding.517.14, Induction,see aLso Induction Control transformers and Cellular concrete floor raceways, 517,19(D) and dielectric heating resistors,503.120 372.2.372.5.372.9 Receptacles,517.13,517.16, equipment Cranes and hoists.503.155, Cellular metal fluor raceways, 517.19M)(2),517.19(G) Definition,427.2 610.3(A)(3) 374.2,374.6 Wet locations,517.20 Integrated Exposed pans,503.25 Definition,372.2,374,2 Wiring methods.517.12 Definition,427.2 Flexible cords,503.140 Health care facilities,Art. 517 X-ray installations,517-V Skin effect Fuses,503.115 Communications,signaling sys- Connection to supply circuit. Definition,427.2 Grounding,503.30 tems,data systems,less 517.71 Heavy-duty Iampholders Luminaires,503.130 than 120 volts, nominal. Control circuit conductors. Branch circuits,210.21(A), Motor controllers,503.115 517-VI 517.74 210.23,Table 210.24 Motors and generators,502.125 Other-Than-patient care areas, Disconnecting means,517.72 Unit loads,220.14(E) Receptacles and attachment 517.81 Equipment installations, Hermetically sealed,500.7(J) plugs. 503.145 Signal transmission between 517.75 Definition,500.2 Signaling,alarm,remote-control, appliances,517.82 Guarding and grounding, Hermetic refrigerant motor- and local loudspeaker Definitions,517.2 517.78 compressors,see also intercommunications, Essential electrical systems, High tension x-ray cables, Air-conditioning and 503.150 517--111 517.77 refrigerating equipment Storage battery charging equip- Ambulatory health care cen- Overcurrent protection, Ampacity and rating,440.6(A) men).503.160 tern,517.45 517.73 Definition,440.2 70-802 NATIONAL ELECTRICAL CODE 2008 Edition INDEX Instructions Marking,410.4 Lighting load,Table 220.12 Incandescent lamps,Art. 410;see Flash protection, 110,16 Rating and interrupting capacity, Lighting outlets required, also Hazardous(classi- Grounding,409.60 440.12(A) 210.70(B) fied)locations Installation,409-II High density polyethylene Overcurrent devices,guest Guards Marking,409.110 conduit(Type HDPE), rooms and suites, Aircraft hangars,513.7(0) Overcurrent protection,409.21 Art.353 240.24(E) Garages,511,7(B) Service equipment,409.108 Bends,353.24,353.26 Receptacle ground-fault circuit Theater dressing rooms, Spacing,minimum,409.106 Bushings,353.46 interrupter protection, 520.72 Wiring space in,409.104 Construction specifications. 210.8(B) Lamp wattage,marking on Industrial installation,supervised 353-111 luminaire(fixture), Definition,240.2 Receptacle outlets,guest roams protection,240- rent Definitian,353... and suites,210.60, 410.120 Overcurrent Grounding,353.60 210.70(B), 220.14(1) Medium and mogul bases. Industrial machinery,Art 670 Installation,353-II Hot tubs see Spas and hot tubs 410.103 y, P Definition,670.2 Joints,353.4R 'see with lamp holders for, Houseboats,see Floating buildings Disconnecting means,670.4(B) Listing,353.6 600.4(13) 6 82 705 Hybrid systems, . Nameplates, 670.3 Marking,353.1_0 Snap switches for,404.14!8)(3) � Definition,705.2 Supply conductors and overcur- Number of conductors, 353...2.. Independent Hydromassage bathtubs,680-VII rent protection,670.4 Size,353.20 Definition,680.2 Circuits for emergency lighting, Industrial manufacturing system Splices and taps,353.56 700.17 Definition,670.2 Trimming ends,353.28 Supports,services,over build- Information technology a ui Uses not permitted,353.12 ings,230.29 q p- ment,Art. 645 Uses permitted,353.10 _1_ Wiring,emergency circuits, Cables not in information tech- High-impedance grounded Identification,see alsa Color 700.9(B) tech- nology equipment -ray control,66 .24 neutral systems, X 0 gy P code;Markings rooms,645.6 250.20(E), 250.36, Critical operations power sys- Individual branch circuits,see Definitions,645.2 250.186 tens wiring,708.10(A) Branch circuits, Disconnecting means,645.4(1), Hoists,Art.610.see also Cranes individual Direct-buried cables,Table 645.10 Conductors,contact,610-1II 300.50 Note d Induced currents,metal enclo- Grounding,645.15 Control,610-VI Disconnecting means, 110.22, sures,300.20, 330.31 Marking,645.16 Electrolytic cells, 668.32 Induction and dielectric heating penetrations,645.7 D 51 620 B) 70( , . ( ) Flexible cords,400.7(A)(5) 230. equipment,Art.665 Power distribution units,645.17 Grounding,250.22(1), Service disconnects,230,2(E) Ampacity of supply conductors, Special requirements for infor- 250.1 12(E).250.116(1). Emergency circuits and systems, 665,10 700.9(A) nation technology 610-VII Definitions,665.2 equipment rooms,645.4 Hazardous(classified)locations, Feeders,215.12 Disconnecting means,665.12 Supply circuits and interconnect- 503.155 Flexible cords Guarding,grounding,and label- ing cables,645.5 Marinas and boatyards,555.23 Equipment grounding con- ing,665-11 Uninteruptible power supplies Motors and controllers,discon- ductors,400.23 Access to interior equipment, (UPS),645.11 necting means,430.112 Grounded conductors, 665.22 Infrared lamp industrial heating Ex.,610-IV 200.6(C),400.22 Capacitors,665.24 appliances,422.14, Overcurrent protection,610-V Fuel cell systems,692.4(B) Component interconnection, 422.48 Wiring,610-11 Grounded conductors,Art.200, 665.19 Branch circuits,210.23(C), Hoistways 400.22,402.8 Control panels,665.21 422.11(C),424.3(A) Busways in,168.12(B) Grounding-pole,406.9(B) Enclosures,665.20 Overcurrent protection. Cablebus in,370.3 High-leg, 110.15,230.56, Grounding and bonding, 422.11(C) Definition,Art. 100-1 408.3(E),408.3(F), 665.26 Inhalation anesthetizing loca- Surface metal raceways, 409,102 Marking,665.27 lions,see Anesthetizing 386.12(4) Intrinsically safe systems, Shielding,665.25 locations Wiring in,620.21(A)(1),620.37, 504.80 Warning labels or signs, Inserts 725.136(I), Sensitive electric equipment 665.23 Cellular concrete floor raceways, 760.53(A)(3). conductors, 647.4(C) Hazardous(classified)locations, 372.9 760.130(B)(3). 665.4 Cellular metal floor raceways, Service disconnecting means, 374.10 760.136(F) 230.70(B) Output circuits,665.5 Underfloor raceways,390.14 Hoods,metal,stage switchboard, Ungrounded conductors, Overcurrent protection, 665.11 In sight from 520.24 Remote control,665.7 210,5(C),215.12(C) Air-conditioning or refrigerating Hoods,range,cord-and-plug- Induction heating Wiring device terminals, equipment.440.14 connected,422.16(8)(4) Definition,665.2 250.126,504.80 Center pivot irrigation machines, Hoods for commercial cooking, Inductive loads Identified 675.8(B) lighting in,410,10(C) Motors,430.83,430.109 Definition,Art. 100-1 Definition,Art. 100-1 Duct heaters,424.65 Hospitals,see also Health care Signs,fi00.6(B) facilities Illumination,see also Lighting; Switches,types,ratings,404.14 Electric-discharge ters, lighting, Definition,517.2 Luminaires Industrial control panels, g g Essential electrical systems, Means of egress,517.32(A), Art 409 electric pac 517.30 517.42(A) Conductors Fixed electric equipment, 74,198 Patient care areas,see Patient Task,517.33(A) Busbars,409.102 equipment,424,l9(A) Motor driven appliances,422.32 Definition,517.2 p y Motors,motor controllers, care areas Minimum size and am acit , Psychiatric Immersible appliances,422.41 409,20 430.102 Definition,517.2 Immersion heaters,cord-and- Construction specifications, Room air conditioners,440.63 Hotels and motels plug-connected,422.44 409-111 Signs,600.6(A) Branch-circuit voltages,guest Immersion pools,see Swimming Definition,409.2 Institutions,emergency lighting, rooms and suites, pools,fountains,and Disconnecting means,409.30 Art. 700 210.6(A) similar installations Enclosures,409.100 Instructions, 110,3(8),230.95(C) 2008 Edition NATIONAL ELECTRICAL CODE 70-803 Instrumentation tray cable (Type ITC) INDEX Instrumentation tray cable(Type Directory,705.10 Wiring methods,504.20 Joists ITC),Art. 727 Disconnect device,705.22 Introduction,Art,90 Air-handling,space, Allowable ampacity,727.8 Disconnecting means Inverter 300.22(C) Ex, Bends,727.10 Equipment,705.21 Definition,690.2 Armored cable, 320.23(A) Construction,727,6 Sources,705.20 Utility-interactive Concealed knob-and-tube wir- Definition,727.2 Equipment approval,705.4 Definition,Art. 100-I ing.394.23 Marking,727.7 Generators,705-I11 Irons,see Flatirons Electric space heating cables, Overcurrent protection,727.9 Ground-fault protection,705.32 Irrigation machines,Art.675 424.41(J) Uses not permitted, 727.5 Grounding,705.50 Bonding,675.14 Holes through or notches in. Uses permitted,727.4 Interrupting and short-circuit Center pivot,675-II 300.4(A) Instruments,meters, relays current rating,705.16 Definition,675.2 Nonmetallic sheathed cable, Grounding,250-IX Loss of 3-phase primary source, Collector rings,675.11 334.15(C) Hazardous(classified) lactation. 705.42 Conductors,675.9 Open wiring crossing. 501.105,502.150 g' g• Loss of primary source,705.40 Uerating of,675.5 398.15(C) Low-voltage, rum nit transformers,s form Output characteristics,705.14 Current ratings,equivalent, Parallel to framing members. Instrument transformers,see Overcurrent protection,705.30 675.7 cables and raceways. Transformers, fnstru Point of connection,705.12 Definitions,675.2 300.4(D) ment,grounding Synchronous generators, Disconnecting means,675.8 Jumpers,bonding,250.168 Insulation 705.143 Grounding 675.12,675.13 Cable trays, 392.6(A) insulation Conductors,see Conductors, Intermediate metal conduit(7�'pe Irrigation cable.675.4 Definition,Art. 100-1 Double,see Double insulated IMC),Art.342 Lightning protection,675.15 Equipment, 250.98, 250.102 Equipment, 110.3(A)(4) Bends,342 24,342.26 Marking,675.6 Definition,Art. IW-I Fixture wire,402.3.Table 402.3 Bushings,342.46 Motors on branch circuit,675.10 Generators, 250.35(B) Flexible cords.400.4.Table Construction,342-III Supply source,more than one, High-impedance grounded 400.4,400-II Couplings and connectors, 675.16 neutral system, Heating cables,424-V 342,42 Isolated 250.36(E),25036(G) Luminaire and lampholder pans, Definition.342.2 Arcing parts, I10.I8 Size,250.30(A)(2) 410.42(B),4 10.100 Dissimilar metals,342.14 Circuits, low voltage,517.64(C) Solar photovoltaic systems, Insulators Installation,342--II Definition,Art. 100-I 690.50 Nonabsorbent,230.27, Listing,342.6 Equipment grounding conductor, Expansion joints,telescoping 394.30(A) Maximum number of conductors 250.146 FPN sections of raceways, Open wiring,.tee Open wiring and fixture wires in, Phase installations,300,5(1) 250.98 on insulators Tables C4 and C4A Ex. 2 Grounding electrode system, Integrated electrical systems,Art. Number of conductors.342.22 Power systems,517.160, 250.53(C), 250.64(F) (185 Reaming and threading,342.28 517-VII Grounding-type receptacles, Applications of other articles. Size,342.20 Definition,517.2 250.146 685.3 Splices and taps,342.56 Essential electrical systems, Hazardous(classified)locations, DC system,rounding.685.12 Standard lengths,342.130 517.30(C)(2) 250.100,501.30(A), Orderly shutdown,645,10 Ex., Supports and securing,342.30 Grounding,517.19(F), 502.30(A),503.30(A), 645.11,685-11 Uses permitted, 342.10 647.7(B) 505.25(A) Overcurrent protection, location Wet locations, 342.10(D) Installation,517.160(A) Health care facilities,517.19(C) of,685.10 Intermittent duty Isolating means,over 600 volts, and(D) Ungrounded control circuits, Definition,Art. 10(>_-I 490.22 Main, 250,24(B),250.28 685.14 Motors,430.22(E),430.33 Isolating switches,see Switches, Definition,Art. IWA Integrated gas spacer cable(Type Interpretations,formal,.see For- isolating Wire or bulbar,as, IGS),Art.326 mal interpretations Isolation by elevation 250.24(A)(4) Construction. 326-111 Interrupter switch,see Switches, Circuits over 600 volts, Metal, structural,250.104(C) Conductors,326.104 inierru ter P 110.34(E) Network-powered broadband Conduit,326.116 Interrupting rating, 110.9, Circuits under 600 volts, communications system, Insulation, 326.112 240.60(C)(3),240.83(0 830.1W(D) Marking,326.120 Definition,Art. 100-I 110. rear Optical fiber cables,770AMD) Definition,326.2 Resistors and reactors over 6UU p Intersystem bonding termination volts,470.18{B) Piping systems,250.104 Installation,326-11 Definition,Art, 100-I Ampacity,326.8(} Isolation equipment,systems Separately derived systems, � ., Intrinsically safe apparatus 250.30(A) Bonding.radius,3_6._4 (motors),430.I09(A)(7) Bends, 32fi?6 Definition.504.2 Definition,430.2 Service equipment,250.28, Grounding,504.50(A) Isolation transformer,see Trans- 250.92(B),250.102(C) Fittings,3..6.40 , Intrinsically safe circuits System,250.28, 250.30(A)(1) Uses not permitted,326.1 L farmers,Isolation Y Uses permitted.326.10 Definition,504.2 Definition,250.2 Interactive systems Intrinsically safe systems,Art. Junction boxes,see also Boxes; Definition,Art. 100-1, 690.2 504 Pull boxes Fuel cell systems,connection to. Bonding,504.60 -J- Accessibility,314.29 692--VII Conductors, separation of, Joints,see also Splices and taps Cellular concrete floor raceways, Intercommunications systems,see 504.30 Expansion,see Expansion joints 372,7 Communications Definitions,504 2,506.2 Grounding electrode conductor, Cellular metal floor raceways, circuits: Hazardous Equipment installation,504.10, 250.64(0 374.9 (elassified)locations 506.8(C),506.8(K1 High density polyethylene con- Covers,314.28(C),314.72(E) Interconnected electric power Equipment listing,504.4 duft,353.48 Deicing and snow-melting production sources, Grounding,504,50 Insulating,fixtures,410.36(D) cables,426.22(E), Art.705;see also Identification,504.80 Insulation of, 110,14(B) 426.24(B) Utility-interactive Sealing,504.70 Reinforce thermosetting resin Motor controllers and discon- inverters Separation of intrinsically safe conduit,355.48 nects.430.1O(A) Definitions.705.2 conductors,504.30 Strain at,400.10 Nonheating cable leads,424.43 70-804 NATIONAL ELECTRICAL.CODE 2008 Edition INDEX Lightning(surge)protection Over 600 volts,3144V Lacquers and paints Footlights,520.43 Branch circuits,calculation of Sensitive electronic equipment, Application,Art.516 Stage,arc,portable,520.61 load,220.12 647.4(B) Atmospheres,500.5(B), Switchboards,pilot lights, Cove,410.18 Separation from motors, 500.6(A),Art.501, 520.53(G) Decorative,410-XVI 430.245(B) 505.5(B),Art.505 Wattage marking, Hush and re- Electric discharge,see Electric Size Lampholders cessed luminaires, discharge lighting Conductors 4 AWG and Branch circuits supplying, 410.120 Emergency,Art.700 larger, 314.16. 210.23 Laundry Exits,see Exits,emergency 314.28(A) Circuits less than 50 volts,720.5 Circuit load,220.52(B) lighting Conductors 6 AWG and Construction,410-IX Outlets smaller,314.16(C)(1) Dam or wet locations, Feeders,calculation of load, Damp Dwelling,210.11(0}(2), Construction specifications, 410.10(A),410.96 210.50(C),210.52(F) 220.42,220-IV 314-III Double-pole switched,410.93 Festoon,see Festoon lighting Po Ground-fault circuit interrupt- Supports.314.23 Heavy-duty,see Heavy-duty ers,210.S(A)(7) Fixtures,see Luminaires Swimming pools,680.23(C), lampholders Mobile homes,550.13(D)(7) Outlets,see Lighting outlets 680.24 Infrared lamps,422.14 Outline,see Outline lighting Switch enclosures, 110.59, P Laundry area,2(C),5F), Installation,410-VIII 550.12{C),550.13(D)(7) Sensitive electronic equipment, 312.8.404.3(B) Mogul base,see Mogul base Definition,550.2 647.8 Underfloor raceways,390.13 lampholders Leakage-current detector- Systems,see Lighting systems, Outdoor,225.24 interrupter,440.65 30 volts or less Pendant Definition,440.2 Track,see Lighting track 'x- Bathrooms,410.10(D) Legally required standby sys- Lighting assembly,cord-and- Kitchen Not in clothes closets, Definition.Art. 100-1 410.16(B) terns,Art.701 plug-connected Receptacles in,210.8(A)(6) Accessibility,701.15 Definition,680.2 P Not in theater dressing Approval,equipment,701.4 Lighting outlets,210.70, Kitchen equipment,commercial, rooms,520.71 220.56,422.11(F)(2) Capacity and rating,701.6 314.27(A),410.36(A), Screw-shell types for lamps Circuit wiring,701.10,701-II 410-III Knife switches only, 410.90 Butt contacts,404.6(C) Definition,701.2 Definition,Art. 100-I Switched,d over Ground-fault protection of Connection,404.610) P Lighting systems,30 vans or less, Unswitcma over combustible equipment,701.17 Construction specifications, material,410.23 Art.411 404-11 Overcurrent protection 701-1V Branch circuit,411.6 .3 noires; Hazardous(clan- Lamps,Art.410;see also Lumi- Definition.411.2 Enclosures,404 Signals,701.8 Signs,,70[.9 General-use,404,13(0) sifted)locations g Hazardous(classified)locations, Po wer,701-III or Interrupt current,404.13(8) Arc,see Arc lamps,portable Sources 411.7 Isolating,404.13(A) 70 ,Tests and maintenance 1.5 Backstage(hare hulb), 520.47 Listing required,411.3 Motor-circuit,404.13(D) Transfer equipment,701.7 Clothes closets,in,410.16 Locations not permitted,411.4 Position,enclosed and open Electric discharge,410.62(C), Wiring,701.10 Secondary circuits,411.5 types,404.6 Lengths 410.104,410-XIII, Lighting track,410-XV Ratings,404.14 410-XIV Branches from busways, 600-volt,404.16 368.56(B) Construction requirements, Electric discharge,auxiliary 410.155 Knob-and-tube wiring,Art.394 Free conductors at outlets and Accessible attics,394.23 equipment enclosure, switches,300.14, Definition,410.2 41t,see A) Fastening,410.154 Clearances,394.19 424.43,426.23 g• Fluorescent,see Fluorescent High density polyethylene con- Heavy-duty,Conductors,394.104 luminaires(lighting Hea dot ,410.103 Construction 394-I1I duit,marking, 353.120 Installation,410.151 Definition,394.2 fixtures) Guards,see Guarding,guards Intermediate metal conduit, Load calculations,220.43(B) Devices,394.42 342.130 Lightning rods Installation.394-11 Headlamps,see Handlamps, portable Open wiring in nonmetallic Hex- As a ground,250.60 Securing and taps,39 .56 394.30 p° ible tubing,398.15(A) Irrigation machines,675.15 Splices and to s,394.56 Incandescent,see Incandescent P P Through or parallel to framing lamps Pull and junction boxes, 314.28, Spacing from, 250.106 FPN No. members,394.17 Infrared,see Infrared lamp in- 314,71 2 Uses not permitted, 394.12 duslrial heating appli- Rigid metal conduit,344.120, Lightning{surge}arresters, Uses permitted,394.10 ances 344.130 Art,280 ro Motion picture projectors, Rigid polyvinyl chloride con- Antenna discharge units,810.20 Knockouts P P ] g Bonding 540.14,540.20 duit,marking,352.120 Connections at services, Over 250 volts,250.97 Ex. Motion picture studios Space-heating cable,nonheating 230.82(4) Service equipment,250.92(B) Film storage vaults,530.51 leads,424.34 Definition,Art. 100-1 ,es Sta portable,530.16, Taps,210.19(A)(4)Ex. 1, Openings to he closed, g � 240,21,240.92(B) Grounding,250.60,250.106, 110.12(A),314.17(A) 530.17 280.25 Viewing,cutting tables, Motor branch circuit, Radio and television equipment 530.41 430.53(D) Outdoor,location, 225.25 Motor feeders,430.28 Receiving stations(antenna Labeled Pendant conductors,410.54 Life safety branch discharge units},510.20 Definition,Art. 100-1 Portable,see Portable luminaires Definition,517.2 Transmitting stations,antenna Labels required,550.20(B), Stand Essential electrical systems, discharge units. 2 030.2 09 . 550.32(G),551.46(D), Definition,520.2,530.2 517.32,517.42 Services over 600 volts,22 551.47(Q)(3), Theaters Life support equipment, Lightning(surge)protection,Art. 551.47(8)(4), Border and proscenium, electrical 280;see also Surge- 552.44(D),552.48(P)(3), 520.44 Definition,517.2 protective devices 552.59(B); see also Dressing rooms,lamp guards, Lighting (SPDs) Warning signs(labels), 520.72 Airfield lighting cable, Communication circuit conduc- at equipment Festoons,520.65 310.7 Ex. 2 tors,800.53 2008 Edition NATIONAL ELECTRICAL CODE 70-805 Lightning (surge) protection INDEX Connections at services.230.82 Listed Elevator motor disconnecting Hermetic refrigerant motor. Hazardous(classified)fixations, Definition,Art. 100-1 means,620.51(C) compresaurs,440.4(A) 501.35,502.35 Live parts,see also Enclosures; Foreign pipes,accessories,trans- Locknuts,double,required Hoistways and machine rooms, Energized parts;Guard- former vaults,450.47 Hazardous(classified)locations, 620,37(B) ing,guards Generators,445.10 501.30(A) Network-powered broadband Capacitors,460.2 Grounding connections at elec- Mobile homes,550.15(F) communications sys- Definition.Art. 1004 trodes,250.68 Over 250 volts to ground, tems, 830.44(1)(3) Elevators,dumbwaiters,escala- Hazardous,see Hazardous(clan- 250.97 Ex. Lights,see also Lamps; Lighting; tors,moving walks, sifted)locations Recreational vehicles,551.47(B) Luminaires platform lifts,and stair- Intrinsically safe equipment, Low-voltage circuits,see also Border,520.44(A) way chairlifts,620.4 504.10(B) Remote-control,signal- Cables for, theaters, Exposed, l 10.26 Larnps.outdoors,225.25 ing,and power-limited 520.44(B) Flash protection. 110.16 Luminaires,410-1I circuits Definition.520.2 Generators,protection,445.14 Mobile homes disconnecting Definition,551.2 From railway conductors, Guarding, 110.27 means and branch- Less than 50 volts, Art.720 110.19 Lampholders,410.5,410.142 circuit protective equip- Lugs Scenery,theaters,halls,520.63 Lamp terminals,410.142 ment.550.11 Connection to terminals, Strip Lighting systems,electric dis- Motion picture projection equip- I10.14(A) Definition,520.2 charge,410-XIIL merit,540.11 Listed type at electrodes,250.70 Limited care facilities,see also 410-XIV Motor disconnecting means, Luminaires,Art.410.see also Health care facilities Luminaires and lamps,410.5, 430.102 Hazardous(classified) Definition,517.2 410.86,410.140(C) Motor feeder taps,430.28 Ex. locations Essential electrical systems, Over 600 volts,490.24,490.35 Motors,430.14 Arc,portable,520.61,530.17 517.40 In theaters,520.7 Outlet boxes and conduit boxes, Autotransformers Line isolation monitor, Transformers,guarding, 314.29 Ballasts supplying fluorescent 517.160(6) 450.8(C) Overcurrent devices,240-II luminaires,410.138 Definition,517.2 In tunnels, 110.56 Overhead service,230.54 Supply circuits,210.9, 215.11 Lint,flyings,Art.503,Art.506 Loads Panelboards,damp or wet, Auxiliary equipment,410.137 Liquidtight flexible metal conduit Appliances,household cooking, 408.37 Bathtubs, near,410.10(D), (Type LFMC),Art. 350 demand table,220.55 Protective devices for communi- 550.14(D),551.531B) Bends,350.24, 350.26 Branch circuits cations circuits, Boxes,canopies,pans,410.78, Couplings and connectors, Calculations,Art. 220, 800.90(B), 830.90(B) 410-111 350.42 Annex D Recreational vehicle disconnect- Branch circuits Definition, 350.2 Maximum,210.25,220.18 ing means and distribu- Computation of, 210.19(A), Grounding and bonding,350.60 Mobile homes,550.12 tion panelboard, 220.12,220.14 Installation,350-11 Permissible,210.23,210.24, 551.45(B) Sizes,210.23,220.18 Listing,350.6 Table 210.24 Resistors and reactors,470.2 Voltages,210.6,410.130 Maximum number of conductors Continuous,see Continuous load Service disconnecting means, Clothes closets,410.16 and fixture wires in, Demand 230.70(A), Definition,410 2 Combustible material,near, Tables C7 and C7A Clothes dryers,220.54 230.72(A)Ex. title ,410.136 material.n Number of conductors and Household cooking appli- Service overcunent protection. Connection, fluorescent,410.24, cables in,350.22 ances,220.55 230.91,230.92 4lU.62(C) Securing and supporting, 350.30 Farm,220-V Shooting Construction,410.155,410-VII, Size, 350.20 Feeders,calculations for, Definition,530.2 , 410-X 410- Uses not permitted,350.12 215.2(A),Art.220,An- Sign switches,600.6(A) Cords, see Cords, Uses permitted,350.10 nex D Splices and taps Flexible Liquidtight flexible nonmetallic Electrified truck parking Auxiliary gutters,366.56 Dip wet,Flexible corrosive loca- tions,(Type LFNC), space equipment,626,2 Wireways,376.56,378.56 [ions, corrosive Art. 356 Inductive,see Inductive loads Surge arresters,280.11 410.10(B),410.30(B) Bends, 356.24,356.26 Mobile home parks,550.31 Surge protective devices,285.11 Decorative lighting.410-XVI Construction specifications, Mobile homes,550.18 Swimming pool junction box Definition,Art, 1001 356-111 Motors,conductors,43(-II and transformer enclo. Dry-niche,680.23(C) Couplings and connectors, Nonlinear sores,680.24 Definition,680.2 356.42 Definition,Art. 100-1 Switchboards,408.16,408.17, Ducts or hoods, in,410.1O(C) Definition, 356.2 Service,calculations for,Art. 408.20 Electric discharge,see Electric Grounding and bonding, 356.60 220 Switches,damp or wet,404.4 discharge lighting Installation,356-11 Stage equipment,circuit loads, System grounding connections, Fluorescent,see Fluorescent Listing,356.6 520.41 250-11 luminaires Marking, 356.120 Location board Transformers and vaults,450.13 Flush,410-XI,410-XII Maximum number of conductors Definition,530.2 Unclassified Fountains,680.51 and fixture wires in, Locations Definition,500.2,505.2 Grounding,410-V Tables C5 through C6A Capacitors,460.2(A) Ventilation openings for trans- Indoor sports,mixed-use,and Number of conductors or cables Crane and hoist disconnecting former vaults, all-purpose facilities, in,356.22 means,610-IV 450.45(A) use in,410.10(E) Securing and supporting, Damp or wet,see Damp or wet Wet,see Wet locations; Damp Inspection,410.8 350.30,356.30 locations or wet locations Listing,410.6 Size,356.20 Definition,Art. 100-1 Locked rotor motor current Live parts,410.5 Splices and taps,356.56 Dry,see Dry location Code letters,430.7(B).Table Location,410-II Trimming,356.28 Electric discharge lighting trans- 430.7(B) Mounting,410.136,410.137 Uses not permitted,356.12 formers,over 1000 Conversion,Tables 430.251(A) No-niche,680.23(D),680.24(B), Uses permitted,356.10 volts,410.144 and(B) 680.26(B)(4) 70-806 NATIONAL FLECfRICAL CODE 2008 Edition INDEX Mobile homes Definition,680.2 Grounding electrode conductor, Installation,328-II Hazardous(classified)locations, Outlets required,see Lighting 545.12 Messenger-supported wiring,Art. 501.105,502.150 outlets Protection of conductors and 396 Meter socket enclosures,see Overcurrent protection, wires equipment,545.8 Definition,396.2 Cabinets,cutout boxes, and cords,240.5 Receptacle or switch with inte- Grounding,396.60 and meter socket enclo- Polarization,410.50 gral enclosure,545.10 Installation 396-II sures Portable,see Portable luminaires Service-entrance conductors, Messenger support,396.30 Metric equivalents Raceways,410.30(B),410.64 545.5,545.6 Splices and taps,396.56 Raceways,trade sizes,300.1(C) Recessed,see Recessed lumi- Service equipment,545.7 Uses not permitted,396.12 Metric units of measurement, naires Supply conductors,545.5 Uses permitted,396.10 90.9 Recreational vehicles.551.53 Wiring methods,545.4 Metal-clad cable(Type MC), Mineral-insulated metal-sheathed Showers,near,410.10(D), Manufactured homes,see also Art.330 cable(Type MI), 550.14(D),551.53(B) Mobile homes;Recre- Accessible attics,330.23 Art.332 Show windows,410.14 ational vehicles Ampacity,330.80 Ampacity. 332.80 Supports.410-IV Definition,550.2 Bends,330.24 Bends, 332.24 Swimming pools,spas, and Manufactured phase Boxes and fittings,330.40 Conductors,332.104 similar insta lations, Definition,455.2 Conductors,330.104 Construction specifications, 680.22(C),680.23, Marking,455.6(B) Construction specifications, 330-III 680.26(B)(4),680.33, Manufactured wiring systems, 330-111 Definition,332.2 680.43(B),680.51, Art.604 Definition,330.2 Lquipment-grounding conduc- 680.62(F),680.72 Construction,604.6 Equipment grounding conductor, tors,332.108 Theaters,Art.520 Definition,604.2 330.108 Fittings,332.40 Wet,410.10(A),410.30(B) Installation,604.7 Installation,330-11 Installation,332-II Wet-niche,680.23(B) Uses not permitted, 604.5 Insulation,330.112 Insulation,332.112 Definition,680.2 Uses permitted,604.4 Marking,310.11 Sheath,332.116 Wiring,410-V1 Marinas and boatyards,Art. 555 Sheath,330.116 Single conductors,332.31 Luminaire stud construction. Circuit breakers,555.11 Single conductors,330.31 Supports,332,30 410.36(C) Connections,555.9 Supports,330.30 Terminal seals,332.40(B) Cranes,555.23 Through or parallel to framing Through or parallel to framing Definitions,555.2 members,300.4(A), members,300.4,332.17 _M_ Disconnecting means,555.17 330.17 Uses not permitted,332.12 Machine rooms Distribution system,555.4 Uses not permitted,330.12 Uses permitted, 332.10 Branch circuits,lighting and Enclosures,555.10 Uses permitted,330.10 Mobile home lot receptacles,620.23 Ground-fault circuit interrupters, Metal-enclosed switchgear,see Definition,550.2 Definition,620.2 555.19(B)(1) Switchgear,metal- Mobile home parks,Art.550 Guarding equipment, 620.71 Grounding,555.15 enclosed Definitions,550.2 Wiring, 620.21(A)(3),620.37 Hazardous(classified)locations, Metal frame of building Distribution system,550.30 Machinery space 555.21 Bonding,250.104(C) Electrical wiring.system Branch circuits, lighting and Hoists,555.23 Grounding electrode, Definition,550.2 receptacles, 620.23 Load calculations,555.12 250.52(A)(2) Feeder and service demand Definition,620.2 Marine power outlets,555.11 Not permitted as equipment factors,550.18,550-III, Wiring,620.21(A)(3) Definition. 555.2 grounding conductor. Table 550.31 Machine tools,see Industrial ma- Motor fuel dispensing,555.21 250.136(A) Minimum allowable demand chinery Panelboards,555.11 Metal gutters,see Auxiliary factor,550.31 Made electrodes,250.50, 250.52 Railways,555.23 gutters Mobile home service equipment, Mandatory rules,90.5(A) Receptacles,555.19 Metal hoods,stage switchboard, 550.32 Manholes, 110-V Service equipment,location, 520.24 Definition,550.2 Access, 110.75 555.7 Metal outlet boxes,see Boxes, Mobile homes,Art.550;see also Covers, 110.75(D) Switches,555.11 metal Park trailers;Recre- Dimensions, 110.75(A) Transformers,555.5 Metals ational vehicles Location, 110.75(0) Wiring methods and installation, Corrosion,protection against, Accessory buildings or Marking, 110.75(E) 555.13 see Protection, structures Obstructions, 110.75(B) Markings, 110.21;see also Identi- Corrosion Definitions,550.2 Conductors fication: subhead under Dissimilar, 110.14,250.70, Appliances,550.12(B)and(D), Bending space for, 1 10.74 entries for specific wir- 342.14,344.14 550.14 Class 1,of different circuits, ing and equipment Ferrous,300.6(A),300.20 Arc-fault circuit-interrupter pro- 725.136(F) Circuit breakers,240.83, Metal siding,grounding of, tection,550.25 Class 2,3 installation, 240.86(A) 250.116 FPN Branch-circuit protective equip- 725.133,725.136(F) Fuses,240.60(C) Metal wireways,see Wireways, ment,550.11 Over 600 volts, Means of egress metal Branch circuits,550.12 300.3(C)(2)(e) Health care facilities,517.32(A) Metal working machine tools and Calculations of loads,550.18 Control circuits installed in, Illumination,517.32(A), plastic machinery,see CATV coaxial cables,bonding 522.24(B)(3) 517,42(A) Industrial machinery and grounding of, Fixed ladders. 110.79 Mechanical execution of work, Meters 820.106 Ventilation, 110.77, 110.78 110.12,640.6,720.11, Connection and location at ser- Communications circuits, Work space, 110.72, 110-73 725.24,760.24,770.24, vices,230.82, 800.106 Manufactured buildings,Art. 545 800.24,820.24,830.24 230.94 Ex.5 Definitions,550.2 Bonding and grounding,545.11 Medium voltage cable(Type Grounding of cases,250.174, Disconnecting means,550.11 Boxes,545.9 MV),Art.328 250.176 Expandable and dual units, Component interconnections, Construction specifications, Grounding to grounded circuit wiring,550.19 545.13 328-1I1 conductor,250.142(B) Feeder,550.33 Definitions,545.3 Definition,328.2 Ex.2 General requirements,550.4 2008 Edition NATIONAL ELECTRICAL CODE 70-807 Mobile homes INDEX Ground-fault circuit interrupter, Sealing,514.9 Hazardous(classified)locations, Multioutlet assembly,Art.380 550.13(B) Underground wiring,514,8 501.125,502.125, Calculation of load,220.14(H) Grounding,550.16 Wiring,514.4,514.7,514.8 503.125,505.16(E)(2), Definition,Art, 100-1 Insulated neutral required, Motor-generator are welders,fee 505.22 Metal,through dry partitions, 550,16(A)(1) Welders,electric Highest-rated or smallest-rated, 380.3 Luminaires,550.14,550.20 Motor homes,.see also Mobile 430.17 Use,380.2 Multiple section, wiring,550.19 homes; Recreational Industrial machinery,Art. 670 Multiple circuit connections, Nameplates,550.11(D) vehicles Liquids,protection from,430.11 grounding,250.144 Network-powered broadband Definition,551.2 Live parts,protection of. Multiple conductors(conductors communications cables, Motors,Art.430 430-XII in parallel),see Con- bonding and grounding Adjustable speed drive and drive Location,430.14 ducton, multiple of,830.106 Systems.430.88,430-X Maintenance,430.14(A) Multiple fuses(fuses in parallel), Optical fiber cables,770.106 Definitions,430.2 Marking,430.7 240.8,404.17 Outdoor outlets,luminaires,air- Air-conditioning units,Art.440 Motor control centers,430.98 Definition,Art, 100-11 cooling equipment. Appliances,motor-driven,sre Terminals,430.9(A) Multispeed motors 550.20 Appliances Motor control centers,430-VIII Branch circuits,430.22(B) Power supply. 550,10 Branch circuits,43(-II Multispeed,see Multispeed Locked-rotor code letters, Receptacle outlets,550.13 motors 430.7(3)(1) Combination loads,430.54, Service equipment,550.32 430.63 Overcurrent protection Marking,430.7(B)(1) Definition,550.2 Overload protection,430-111 Branch circuits,430-IV Overload protection,430.32(A). Testing,550.17 Short-circuit and ground-Fault Combined overcurrent protec- 430.32(C) Wiring methods and materials, protection,43(1 IV tion,430.55 ' Multiwire branch circuit,210.4 550.15 Control circuits,430.7 Taps,430.28,430.53(D) Hazardous Art. l0U-I Mobile X-ray equipment Equipment grounding con- y � Torque motors,430.52(D) doctors,250.122(ll) Hazardous locations,501.40, 660'4(B).650.21 Bushing,430.13 Motor control center,43(},94 502.40, 505.21 Definition,660.2 Capacitor,460,9 Motor feeders, en0-V Module,solar voltaic systems Circuit conductors,430-II Over feeders. volts, 30-V 5 Definition,690,2 Code letters,Table 430.7(B) -N- Mogul base lampholders Overheating,dust accumula- 210.6(C}(3),410.103 Conductors,430-11 tions,430.16 Nameplates,see subhead under Adjustable speed drive sys- Overload rolection,430-I11, entries for specific wir- Monorails 555.23,Art. 610 p Motion picture and television terns,430.122 430.55,430.124, ing and equipment Ampacities,430.6 430.225(B),460.9 Natural and artificially made studios,Art.530 Combination loads,430.25 Overtemperature protection, bodies of water,elec- Definitions,530.2 Continuous duty,430.22(A) 430.126 trical wiring and Dressing rooms,530-III Feeder conductors,sizing, Equipment grounding con- Over 600 volts,430-XI equipment for,Art,682 53{}19 doctors,250.122(D) Part winding,.see Part-winding Definitions,682.2 Film storage vault,530-V Feeder demand factor,430.26 motors Grounding and bonding,682-III Grounding,530.20 Intermittent duty,430.22(E) Rating or setting of branch- Installation,682--II Lamps,portable are,530.17 Motor and other loads, circuit short-circuit and Neat and workmanlike installa- Live puts,530,15 430.24 ground-fault devices, tion, 110.12.640.6(A), Luminaires,portable,530.16 Several motors,430.24 'fable 430.52 720.11,725.24,760,24, Overcurrent protection,530.18, Single motor,430.22 Restarting,automatic,430.43 770.24,800.24, 820.24, 530.63 Wound rotor secondary, Short circuit protection,430-IV, 830.24 Portable equipment,530.6 430.23 430-V Neon tubing,600.41 Stage or set,530-11 Control centers,see Control Starting,shunting,430.35 Definition,600.2 Substations,530-VI centers Swimming pools,fountains, and Network interface unit Viewing,cutting, and patching Control circuits,430-V1 similar installations, Definition,830.2 Controllers,see Controllers, 680.21,680.27(B)(1) Network-powered broadband tables,530 [V Wiring motor System isolation equipment, communicatio ns s s - Permanent,530.11 Current,full load,see Full-load 430.109(A)(7) tems,Art.830 Portable,530.12 current motor Definition,430.2 Access to electrical equipment Curtain,theater,520.48 Tables,430-XIV behind panels, 630.21 Motion picture projector rooms, Taps,430.28,430.53(D) Buildings, 830-11.830--V see Projector rooms, Definitions,43{},2 � Disconnecting means,430.75, Terminal housings,430.1_ Cables outside and entering motion picture g 430.245(A) buildings, 830-II Motion picture theaters,see The- 430.95, , Terminals,430.9 Aerial cables, above roofs aters 430.128,,430,2 430,227 Three overload units,Table 830.44(F), Between Motor-circuit switches Feeder demand factor,430.26 430.37 buildings 830,44(H),On Definition,Art. 100-1 Feeders,calculation of load, Ultimate trip current, buildings 830.44(1), Motor control center,see Control 220.40, 220-IV 430.32(A)(2) Clearance from ground centers Full-load current,see Full-load Ventilation,430.14(A),430.16 830.44(D),Climbing Motor fuel dispensing facilities, current motors Wiring diagram,Fig,430.1 space 830.44(B),Final Art.514.see also Haz- Fuseholder,size of,430.57 Wiring Space in enclosures, spans 830.441G), ardour(classified) General.430-1 430.10 Lead-in clearance locations Ground-fault protection,43(}-IV. Mounting of equipment, I10.1-1, 830.44(C), 830.44,On Circuit disconnects,514.11 430-V 314.23,404.9(A), poles 830.44(A),Over Classification of locations,514,3 Grounding, 250-VI,430.12(E), 404.10,410-4V pools 830.44(E) Definition,514.2 430.96,430-XIII Moving walks,see Elevators, Entrance cables,830.40 Equipment,514.4,514.7 Grouped,430.24,430.42, dumbwaiters,escalators, Low-power circuits, Grounding and bonding,514.16 430,53,430.87, moving walks,platform 830,40(B) Maintenance and servicing, 430.112 Ex. lifts,and stairway chair- Medium-power circuits, 514.13 Guards for attendants,430.233 lifts 830,40(A) 70-808 NATIONAL ELECCR[CAL CODE 2008 Edition INDEX Open wiring on insulators Installation methods within, Direct current generators, Uses permitted,382.1OW, Nonpower-limited fire alarm eir- 930-V 445.12(D),445.13 382.10(C) cult(NPLFA),760-IT Installation of cables and Equipment,grounding to, Construction specifications, Definition,760.2 equipment,830.133 250.142 382--III Nontamperable Low-power applications of Feeder load,220.61 Definition,382.2 Circuit breakers,240.82 cables,830.154;duels, Floating buildings,conductors Devices,382.42 Type S fuses,240.54(D) plenums.other air- in,553.9 Exposed,382.15 Number of services,230.2 handling spaces Grounding of Installation,382-11 Disconnecting means,230,71, 830.154(A): Plenums, AC systems,250.4,250.24, Listing.382.6 250.64(D) other wiring 250.26,250.34,250.36 Marking,382.120 Service-entrance conductor sets, 830.154(C);Raceway DC systems,250.4,250.34, Splices and taps,382.56 230.40 830.110: Riser 250.36,250.162(B) Supporting and securing, 382.30 Nurses'stations 830.154(B) High-voltage systems, Uses not permitted,382.12 Definition,517.2 Medium-power wiring, 250.182 through Uses permitted,382.10 Nursing homes,see also Health 830.151,Ducts,ple- 250.186 Nonmetallic-sheathed cable care facilities nums,other air- Identification,Art.200 ('popes NM,NMC,and Definition,517.2 handling spaces Messenger supported wiring, NIVIS),Art.334 Essential electrical systems, 830.15[(A),Plenums, 396.30(B) 517,40 other wiring Point Accessible attics,334.23 830.15](C), Raceway Definition,Art. 100-1 Bends, 3 .24.$0 830.110,Riser Ranges and dryers,grounding, Bends,334.24 830.151(B) 250.140, 250,142(B)Ex. Boxes and fittings,334.40 -O- Conductors,334.104 Occupancy, g Underground circuits entering 1 p y,lighlin loads, buildings, 830.47 Switchboard,stage,520.27(B), Construction,334-III 220.12,Table 220.12 Direct-buried cables and 520.51.520.53(0) Definition,334.2 Office furnishings,Art.605 raceways,830.47(B) Uninsulated,where permitted, Devices of insulating material, General, 605.2 Mechanical protection, 230.22 Ex., 230.30 Ex., 334.40(B) Lighting accessories,605.5 830.47(C) 230.41 Ex.,250.140 Devices with integral enclo- Partitions Pool%.830.47(D) Ex.,338.10(B) sures,334.40(C) Fixed-type,605.6 Underground systems, Neutral systems,high-impedance Equipment grounding conductor, Freestanding type,605.7, 830.47(A) grounded,see High- 334.108 605.8 Definitions,830.2 impedance grounded Exposed work,334.15 Interconnections,605.4 General neutral systems Installation,334-11 Wireways,605.3 Mechanical execution of Nightclubs,Art.518 Insulation,334.112 Official interpretations,see For- work,830.24 Nipples,conduit,see Conduit Listed,334.6 mad interpretations Scope,830.1 nipples Marking,310.11 Oil(filled)cutouts,490.21(D) Grounding methods, 830-IV Noise,see Electrical noise Nonmetallic outlet boxes, Definition,Art. 100-II Bonding and grounding at Nonautomatic 334.40(A) Oil-filled equipment,490.3;see mobile homes, 830.106 Definition,Art. 100-1 Sheath,334.116 also Transformers,oil- Cable network interface unit, Nonelectrical equipment,ground- Supports,334.30 insulated and primary protection, ing,250.116 Through or parallel to framing Oil immersion,500.7(1) 830.100 Nongrounding-type receptacles, members,300.4,334.17 Definition,500.2 Metallic members, 830.93 replacements, Unfinished basements, Oil-insulated transformers,see Listing,830-VI 250.130(C),4063(D) 334.15(C) Transformers Locations,830.3 Nonincendive circuits,500.7(F), Uses not permitted,334.12 On-site power production facility, Marking,830.179(A) 506.8(G) Uses permitted,334.10 695.3(A) Power limitations,830.15 Definition,500.2,506.2 Nonmetallic underground con- Definition,695.2 Protection,830-III Nonincendive component, On-site standby generator, Grounding of metallic mem- 500.7(H) duit with conductors (Type NUCC),Art. 354 695.3(B),695.3(B)(1), bers, 830.93 Definition,500.2 Bends,354.24,354.26 695.6(D)Ex. 2,695.16 Physical damage. protection Nonincendive equipment, Openings 695.2 Bushings,354.46 against, 830.44(I)(4), 500.7(G),506.8(11) p gs in equipment to be 830.47(0), Definition,500.2,506.2 Conductor terminations,354.50 O closed, 110.12(A), 830.100(A)(6),830.157 Nonlinear load Construction specifications, 312.5(A),314.17(A) Primary electrical protection. Definition,Art. 100-I 354-III Open wiring on insulators,Art. 830.90 Nonmetallic boxes,see Boxes, Definition,354.2 398 Grounding,344.60 Types,830.179 nonmetallic Accessible attics,398.23 Neutral,see also Conductors, Nonmetallic conduit,see Liq- Installation,354-II Clearances,398.19 Joints,354.48 grounded uidlight flexible nonme- Conductors,types permitted, Bare,230.22 Ex„230.30 Ex., tallic conduit;Nonme- Listing,344.6 398.104 230.41 Ex. tallic underground Marking,354.120 Construction specifications, Bonding to service equipment, conduit with conductors Number of conductors,354.22 398-111 250.92 Nonmetallic extensions,Art. 382 Size,354.20 Definition,398.2 Busways,over 600 volts, Bends,382.26 Splices and taps,344.56 Exposed work,398.15 368.258 Boxes and fittings, 382,40 Trimming.354.28 Flexible nonmetallic tubing, Common.see Common neutral Concealable Uses not permitted,354.12 398.15(A) Conductor,310.15(B)(4), Bends,382.26(B) Uses permitted,354.10 Installation,398-11 310.15(B)(6),Tables Definition,382.2 Nonmetallic wireways,see Wire- Securing and supporting,398.30 B.310.1 through Exposed,382.15(B) ways,nonmetallic Through or parallel to framing B.310.10 Listing,382,6 Nonpower-limited control circuits members,398.17 Definition.Art, 100-1 Securing and supporting, Amusement attractions, Uses not permitted,398.12 Continuity of, 300.13 382.30(B) 522.10(8) Uses permitted,398.10 2008 Edition NATIONAL ELECTRICAL CODE 70-809 Operable,externally INDEX Operable,externally Cellular metal floor raceways, Suitable for service equip- Electric pipeline, vessel heating Definition,Art. 100-1 374.7 ment,225.36 equipment,427,57 Operating device Underfloor raceways.390.7 Identification,225.37, Electric space-heating equip- Definition,620.2 Heating,air-conditioning, and 230,2(E) ment,424.22 Operating rooms,hospital, refrigeration equipment, Number of supplies, 225.30 Electric vehicle supply equip- 5I7-IV 21463,550.12(D) Outdoor lampholders,225.24, ment, 625.21 Emergency lighting system,Art. Laundry,see Laundry 225.25 Electroplating systems.669.9 700 Lighting.see Lighting outlets Over 600 volts,225-I11 Elevators,dumbwaiters_ escala- Optical fiber cables,Art. 7741 Loads,220.14 Point of attachment,225.16 tors, moving walks, Abandoned cables,770.25 Multioutlet assembly,see Multi- Spacing,open conductors, platform lifts,stairway Definition,770.2 outlet assembly 225.14 chairlifts, 620-V11 Access to electrical equipment. Outdoor,550.20,551.53(C), Supports Emergency systems,700-VI 7711.21 552.41{E),552.59 Masts,225.17 Enclosures,240-I11 Applications of listed cables and Power Open conductors,225.12 Exciters,445.12(A) raceways,770.154 Definition,Art. 100-1 Over buildings,225.15 Feeder taps,240.21, 240.92, Within buildings,770-I11 Receptacle, 210.50 240.92(B),430,28 Definition.Art. 100-1 Vegetation.225.26 Composite cables,770.3{A) Wiring on buildings,225.10 Fire alarm systems, 760.43, Definition,770.2 Dwellings,where required, Outside of buildings,when ser- 760.45,Chap.9,Tables Conductive cable,770.48(A) 210.5 vim considered,230.6 12(A)and 12(B) Definition, 770.2 Required.210-III Fire pumps,230,90(A)Ex,4, Vacuum assembly,central, Ovens,wall-mounted,see also Definitions,770.2.770.6 Y• ' 430.31 FPN, counter- Cooking unit 422 15 , Grounding,770.93,770-IV 695.4(8)(1),695.5(B), Installation,770-IV Outlet spacing,dwelling base- mounted;Ranges 695.5(C) Listing,770.113 board heaters,210.52 Branch circuits, 210.19(A)(3). 210.23(C),220.55, Fixture wires, 240.5,402.1.. Location,505.9(F), 770.3 Outline lighting,Art.600;see Flexible cords,see Cords, Marking,Table 770.179 also Signs Table 220.55 Note 4 flexible g' systems,Bonding,600.7(8) Connections,422.16M)(3). Fuel cell execution of work, 422.31(8} terns, 692.8,692.9 770.24 Definitions,Art. 100-1.600.2 Fuses and fuseholders, 240.8, Grounding,conductor size, Demand factors and loads,Table 240-V, 240.-.VI,404.17 Nonconductive cable,770.48 Definition,770.2 04 67(A),600.24(B) 220.55 Generators.445.12 Output circuits Feeders,calculation of load. Induction and dielectric heating Outside and entering buildings, Amplifiers,640.9(C) 220.82(B)(1) 77O 11 Fuel cells stems,692.61, Grounding,250.140 equipment, nets, Protection,77(1-III Y' g• Industrial control panels,409.21 692-VIII Overcurrent Industrial machinery,670.4(C) Raceway system,7 770.12, Heat generating equipment, Definition,Art. 100-1 Instrumentation tray cable(Type 770.26 .770..1515 4, 665.5 Overcurrent devices see also ITC),727.9 7io 7 Outside branch circuits and Overcurrent protection Integrated electricals stems, Definition. tiles, feeders,Art.225 Branch circuit,240.24(B){2) g 685.10 Y Substitution cables, ems, 4(. Calculation of load,225.3 Definition,Art. 100-I Interconnected electric power Optional standby systems,Art. Branch circuits.220-I, Enclosed,230.208(B) production sources, 702 P 220-II,225.3(A) Standard, 240.6 705.30 Capacity and rating, .5 Feeders,220-III,225.3(B) Overcurrent protection,Art.240 Generators,705.130 Circuit wiring.702-1[1 Circuit entrances and exits, Definition,702,2 Air-conditioning and refrigerat- Utility-interactive inverters, buildings,225.11 in equipment,444-111 705.65 Equipment approval,702.4 Conductors Amusement attractions,522.23 Legally required standby sys- Porable generator erat III Clearance Appliances,422.11 tems,701-IV Portable generator grounding, From buildings,225.19, PP 702.1[) g Single-appliance,210.20 Lighting track,410.153 '`'`5.61 Branch circuits,210.20,240.4 Location,230.91,230.92, Power sources,7U�IV From ground,225.18, 240.92,240-11 Signals,702.7 2 Busways, 368.17 Mobile home,550.11 25.60 Signs,702.8 Capacitors.460.8(B),460.25 Covering_2..25.4 � Motion picture and television 'Transfer equipment,702.6 Size,225.5,225.6,225.50 Circuit breakers,_40-VII P Organs Disconnection,225.31, 225.51 Circuits,remote control, signal- studios,53D.18,530.63 Motors,see Motors Electronic,640.1 through 225.53 ing•and power-limited Multiple fuses and circuit break- Pi Art.650 Class I systems.7_5.43 Pei Lighting equipment installed ers(in parallel), 240.8, Conductors,650.6 outdoors,225.7 Class 2 and Class 3 systems, 404.17 Grounding.250.112(B),650.4 Location of outdoor lamps, Chap.9,Tables 1 I(A) Occupant access to,240.24(B) Installation of conductors, 225.25 and I1(B) Organs,650.8 650.7 Mechanical rotection,225.20 Communications systems,see P Over 600 volts, 1 10.52,240-17C, Overcurrent protection,650.8 More than one building or struc- Communications cir- 460?5,490.52 Source of energy,650.4 ture,225-I1 cuits.protection Panelboards,408.36.408.54, Outdoor receptacles,210.8(A)(3), Access to occupants, 225.35 Conductors,see Conductors 408.55 Ex.I 210.52(E),406,8, Access to overcurrent protec- Cords,flexible and tinsel,240.5. Paralleled fuses and circuit 680.22(A),680.32 tive devices.225.40 400.13 breakers,240.8,404.17 Outlet hoses,see Boxes Disconnect Cord sets,extension,240.5 Park trailers,552.10(E) Outlets Construction,225.38 Cranes and hoists, 610-V Phase converters,455.7 Appliance,210.50(C) Disconnecting means, Critical operations power sys- Recreational vehicle parks, Definition,Art. 100-1 225.31 tents,708-IV 551,74 Devices,branch circuits,210.7 Grouping of,225.34 Current-limiting Recreational vehicles,551-IV, Discontinued Location of,225.32 Definition,240.2 551.43,551.45 Cellular concrete floor race- Maximum number, 225.33 Disconnecting and guarding, Remote-control circuits, ways,372.13 Rating of, 225.39 240-IV 240.4(G),Art. 725 70-810 NATIONAL ELECTRICAL CODE 2UD8 Edition INDEX Periodic duty Sensitive electronic equipment, Enclosed power switchgear and Protection of equipment. Branch circuits,552.46 647.4(A) industrial control assem- 110.34(F) Calculations,552.47 Services blies,490-III Resistors and reactors,470-II Combination electrical systems, Equipment,230-VII Accessibility of energized Separation,490,24,Table 490.24 552.20 Over 600 volts, 230.208 parts,490.35 Services,230-VIII Conductors and boxes,552.48, Solar photovoltaic systems. Arrangement of devices in Shielding solid dielectric- 552,49 690.6(E),690.9 assemblies,490.31 insulated conductors, Connection of terminals and Storage battery prime movers, Circuit breaker locking, 310.6 splices,552.51 480.4 490.46 Solar photovoltaic systems, Cord,552.44 Supervised industrial installa- Circuit breakers-interlocks, 690-IX Definition,552.2 tions,240-VIII 490.45 Temporary,Art.590 Distribution panelboard,552.45. Supplementary,240.10 Clearance for cable conduc- Tray installations,Art. 392 552.55ffl) Definition,Art, 100-1 tors entering enclosure, Tunnel installation, 110-IV Grounded conductors,552.50 Switchboards,408.2 490.34 Voltage regulators,490.23 Ground-fault circuit interrupters, Television studios,see Motion Door stops and cover plates, Wiring methods,300.37,300.50, 552.41(C) picture and television 490.38 Table 300.50, 300-11 Grounding,552,55,552.56 studios Enclosed equipment, 110.31, Low-voltage systems,552.10, 490-III 552.60(B) Theaters,stage switchboards, Fused interrupter switches, _p_ Luminaires,552.10(G),552,54, 52(}.23,520.25(Al' 490.44 552.59 520.50(C),520.52, Panel,solar photovoltaic systems 520.62(B) Gas discharge from interrupt- Definition,690.2 Nominal 120-or 1201240-volt ing devices,490.39 Panelboards,Art.408 systems,552.40, Transformers,450.3,450.4(A), General,490.30 552.60(A) 450.5{A)(2), Bonding,406.40,517.14, Grounding,490,36 517.19(D) Outdoor outlets, fixtures,equip- 450.5(B)(2) Grounding of devices,490.37 Circuit directory,408.4 ment,552.41{E),552.59 Vertical position,enclosures, Guarding,490.32,490.33 Component parts,408.53 Power supply,552.43 240.33 Inspection windows,490.40 Damp or wet locations,408.37 Receptacle outlets required, Welders,630.12,630.32 Interlocks-interrupter Definition,Art. 100-1 552.41,552.53 Welders,electric,630.12(B), switches,490.42,49045 Distribution,550.10(B), 550.11, Switches,552.52 630.32(B) Location of devices,490.41 551.45.551.54(B), Tests, factory,552.60 X-ray equipment,517.73,660.6 Service equipment,490.47 552.45,552.55(B) Wiring methods,552,48 Overhead gantry,626.23 Stored energy for opening, Definition,550.2,551.2 Parts,see specific type such as Definition,626.2 490.43 Enclosure,408.38 Live parts Overhead spans,225.6(A) Enclosure for electrical installa- Flash protection, 110.16 Part-winding motors,430.4 Overload lions, 110.31 General,408.30 Code letter markings, Definition,Art. 100-I Equipment,Art.490 Grounding,408,40,517.19(D) 430.7(B)(5) Protection,see also Overcurrent Fuel cell systems,692-VIII Installation, 110.26(F) Patching tables,motion picture, protection Fuses and£usehoiders. Marking,408,58 530-IV Cranes and hoists,610.43 490.21(B) Overcurrent protection 408.36, Path,grounding,250.2, Fire pumps,695.6(D) Grounding,Art.250,490.36, 408,54,408.55 Ex.] 250.4(A)(5),250.28 Motors,motor circuits,and 490.37.490.74 Relative arrangement of Patient bed location,517.18. controllers,430-II1, Headroom above working switches and fuses, 517.19 430.55,430.225(B), spaces, 110.32 409.39 Definition,517.2 460,9,610.43(A) to(C), Illumination of working spaces, Sensitive electronic equipment, Patient care areas,517.13;see 620.61(B) 110.34(D) 647.4(A) also Health care 31 0.60, Indoor installations, 110.31(B) Service equipment,408.3(C), facilities Ampacity,310.15,31 Over 600 volts,Art. Insulation shielding,300.40 408.36 Ex. 1,408.36 Definition,517.2 392.11,392.13 Isolating means,490.22 Ex.3 Patient vicinity Bending,300.34 Load interrupters,490.21(E) Spacing,minimum,408,56 Definition,517.2 Boxes,pull and junction,314,IV Mobile and portable equipment, Support for busbars and conduc- Pediatric locations,517.18(C! Busways,368--IV 490--IV tors,408,3 Pendant conductors,lamps, Capacitors,460-1I Collector rings,490.54 Use as enclosure,312.8 410.54 Circuit breakers,.tee Circuit Enclosures,490.53 Wire-bending space,408.55 Pendants General,490.51 Working spaces about, 110.26 Aircraft hangars,513.7(B) breakers High voltage cables for main Pans,fixture,410.23 Anesthetizing locations, Circuit c interrupting device power supply,490.56 Paralleled 517.6](B)(3) Ex.2, Circuit interrupting devices, Overcurrent protection, Alternate sources,Art.705 517.61(C)(1)Ex. 490.21 490.52 Elevators,dumbwaiters,escala- Bathrooms,410.10(D) Conductors. I10-III,300.39 Power cable connections to tors,moving walks, Clothes closets,410.16(B) Definitions,Art. 100-11,490.2 mobile machines, 620.f 2(A)(1) Connector,cord,210.50(A) Distribution cutouts,490.21(C) 490.55 Power production sources, Dressing rooms,theater,520.71 Electrode-type boilers,490-V Moisture,mechanical protection, Art.705 Flexible cord,400.7(A)(1) Branch circuit requirements, metal-sheathed cables, Paralleled circuit breakers and Garages,commercial, 490.72 300.42 fuses,240.8,404.17 511,7(A)(2), Electricity supply system, Oil-filled equipment and cutouts, Paralleled conductors,see Con- 511.16(B)(1) 490.71 490.3,490.21(D) ductors,paralleled Hazardous(classified)Class II General,490.70 Outdoor installations, 110.31(0) Park trailers,Art.552.see also locations, Grounding,490.74 Outside branch circuits and Mobile homes;Recre- 502.130(A)OL Pressure and temperature feeders,225--III ational vehicles 502,130(8)(4) limit control,490.73 Ovcreurrent protection, 110.52, Appliance accessibility and fas- Mobile homes,550.14(C) Elevation of unguarded live 240-IX,460.25,490.52 tening,552.58 Periodic duty parts, 110.34(E) Portable cables,400.36 Bonding,552.57 Definition,Art. 100-1 2008 Edition NATIONAL ELECTRICAL CODE 70-911 Permanent plaque or directory INDEX Permanent plaque or directory, CATV coaxial cable. Portable power distribution unit, Programmed power distribution, 225,37, 230.2(E). 820.3(B),820.110, 520.62 see Closed-loop and 705.10 820.154(A),820.179(A), Definition,520.2 programmed power Permission,special 820.182(A) Portable switchboards,theater distribution Definition,Art. 100-I Communications circuits, stages,520-IV Projector rooms,motion picture, Person,qualified 800.154(A),800.179(A), Portable wiring,motion picture Art.540 Definition,Art. 100-1 800.182 studios,530.12 Audio signal equipment,540.50, Phase converters,Art.455 Pliable raceways,.tee Raceways, Positive-pressure ventilation, 540-IV Capacitors,455.23 pliable 500.7(D),501.125(AL Definitions,540.2 Conductors,455.6 Plugging boxes,motion picture 505.8(B),506.8(B) Projectors,nonprofessional, Definition,455.2 studios,530.14, Power,emergency systems,see 540-I11 Different types of,455-I1 530.18(E) I Emergency systems Listing,540.32 Disconnecting means,455.8. Definition,530.2 Power and control tray cable Projection rooms,540.31 455.20 Plugs,attachment,see Attachment (Type TO,Art.336 Projectors,professional type, Equipment grounding connec- plugs Ampacity,336.80 540-11 tion,455.5 Point of common coupling Bends,336.24 Conductor size,540.13 Marking,455.4 Definition,705.2 Conductors,336.104 Conductors on hot equipment, Overcurtent protection,455.7 Point of entrance Construction specifications, 540.14 Power interruption,455.22 Definition,800.2, 820.2,830.2 336-III Flexible cords.540.15 Rotary Polarization Definition,336.2 Listing,540.20 Definition,455.2 Appliances,422.40 Installation,336-II Location of equipment. Start-up,455.21 Connections,200.1I Jacket,336.116 540.11 Static Luminaires,410.50 Marking,336.120 Marking,540.21 Definition,455.2 Plugs,receptacles,and connec- Uses not permitted,336.12 Projector room,540.10 Terminal housings,455.10 tors, 2U0.IG(B) Uses permitted,336.10 Work space,540.12 Photovoltaic systems,see Solar Portable handlamps,410.82(A) Power factor Proscenium photovoltaic systems Receptacle adapters,406.9(B)(3) Definition,Annex D Definition,520.2 Physical damage,see Protection, Screw-shell-type lampholders, Power-limited control circuits Protection physical damage 410.50 Amusement attractions. Combustible material,appli- Pipe,gas,see Gas pipe Poles 522,10(A) ances,422.17 Pipe electrodes,250.52(A)(1), Climbing space,conductors, Power-limited fire alarm circuit Communications systems,see 250.52(4)(5), 250.53, 225.14(D) (PLFA) Communications circuits 250.56,250.66(A), Conductors, mechanical protec- Definition,760.2 Corrosion 250.70 tion, 225.20 Power-limited tray cable R)rpe Aluminum metal equipment. Pipe healing Supporting luminaires, PI TC),725.154, 300.6(B) Cable outlet,mobile home, 410,30(B) 725.154(D)(1), Boxes,metal, 314.40(A), 550.13(E) Pool covers,see Covers 725.179(E) 314.72(A) Cord-and-plug connected assem- Pools,see also Swimming pools, Class 1,Division 2 locations, Cable trays,392,5(0) bly,422.50 fountains,and similar 501.10(8)(1) Conductors,310.9 Pipeline,see also Fixed electric installations Marking,310.11 Deicing,snow-melting equip- heating equipment for Definitions,680.2 Power outlet,see Outlets,power ment,426 26,426.43 and vessels Portable appliances,see A li Power production sources see Electrical metallic tubing, pipelines Pp� AP•- P , Definition.427.2 ances Interconnected electric 358.10(8)Flat conductor cable,324,101 Pipe organs,see Organs,pipe Portable equipment power production General equipment, ,.124 Piping systems,bonding,250.104 Definition,520.2 sources Intermediate metal conduit, Places or assembly,see Assembly. Disconnecting means,517.17(C) Power source,alternate,517.34, 342.1(}(8)and(nd places of Double insulation,250.114 Ex, 551.33 Metal-clad cable, d O.1lfi Plants Generators,250.34 Definition,517.2 Metal equipment, 300.116 Bulk storage.Art.515 Grounding,250.114,250.138 Power supply and(B) Cleaning and dyeing, Conductor size,250.122, Mobile homes,550•10 Mineral-insulated metal- 500.5(B)(1).Art. 501, Table 250.122 Supervisory control and data sheathed cable,332.12 Art.505 High-voltage equipment, acquisition(SCADA), Rigid metal conduit, Clothing manufacturing, 250.188, 250.190 Annex G 344.10(B)and(D) 500.5(D),Art. 503,An. Stage and studio,520.5(B), Power supply assembly,recre- Strut-type channel raceways, 506 520-V,530.6 ational vehicles,551,44 384.100(8) Plate electrodes,250.52(A)(7). X-ray,660.4(B),660.21 Definition.551.2 Underfloor raceways, 250.53,250.56, Definition,660.2 Preassembled cable in nonmetal- 390.2(B) 250.66(A) Portable handlamps,410.82 liic conduit,see Nonme- Ground fault,see Ground-fault Platform lifts,see Elevators, Portable luminaires,410.82, tallic underground con- protection dumbwaiters,escalators, 511.4(B)(2), duit with conductors Ground fault circuit interrupter, moving walks,platform 513.10(E)(1),515.7(0). Premises see Ground-fault circuit lifts,and stairway chair 516A(D) Definition,800.2,820.2 interrupters lifts Flexible cords for,Table 400.4, Premises wiring(system) Hazardous(classified)locations, Plenums,300.22 400.7 Definition,Art. 100-1 500.7,505.8,506.8 Definition,Art. 100-I Handlamps,410.82 Pressure(solderless)connectors Liquids,motors,430.11 Network-powered broadband Live parts,410,5 Definition,Art. 100-1 Live parts. ]10 27,445.14, communications cable.., Motion picture studios,in, Prevention or fire spread,see Fire 450.8(C) 830.3(B),830.154(A), 530.16 spread Motor overload,430.55. 830.179(A)(2) Show windows,showcases. Product safety standards, 430.225(6),4,10-11I Wiring in,300.22 400.11 Ex.2 Annex A Motor overtemperature,430.126 70-812 NATIONAL.ELECTRICAL CODE 2008 Edition INDEX Radio and television equipment Overcurrent,see Overcurrent Recreational vehicle park Ground-fault circuit interrupt- Installed in grooves,300.4(F) protection underground branch ers,680.22(B) Insulating bushings,NX)A(G), Overload,see Overload circuits and feeders, Storable pools,680.31 300.16(B) Physical damage 551.80(B) Purged and pressurized Intermediate metal conduit Armored cable,320.12, Reinforcing thermosetting Definition,500.2 (Type IMC),see Inter- 320.15 resin conduit,355.10(F), mediate metal conduit Audio signal processing,am- 355.12(0) (Type IMC) plificatiun.and repro- Remote-control circuits, Liquidtight flexible metal con- duction equipment, 725.31(B) "Q' duit(Type LFMC),see 640.45 Resistors and reactors, Qualified person,see Person. Liquidtight flexible Busways,368.12(A) 470.18(A) qualified metal conduit(Type Cabinets,cutout boxes,and Rigid polyvinyl chloride con- LFMC) meter socket enclosures, duit,352.12(C) Liquidtight flexible nonmetallic 312.5 Service-entrance conductors, R. conduit tType LFNC), Conductors,250.64(8).300.4, 230.50 Raceways see Liquidtight flexible 300.50(B) Service-lateral conductors, Adjustment factors for more nonmetallic conduit CATV coaxial cable, 230.32 than three current- (Type LFNC) 820.100(A)(6) Space-heating systems, carrying conductors in Luminaires(fixtures)as,410.64 Communications systems, 424.12(A) Network-powered broadband raceway,Table 8.310.1 l 800.100(A)(6) Surface raceways,386.12(l), communications cables. Bonding,250-V,501.30(A), Motor control circuits, 388.12(2) 502.30(A),503.30(A), 830.110,830.133(A)(1), 430,73 Transformers,450.8(A) 505.25(A) 830.154(B)(2) Network-powered broad- OF cable,340.12(10) Busways,see Busways Number of conductors,300.17; band communications Underground installations, Cables trays,supported by, see also Conductor fill cable,830.44(1)(4), 230.32,230.50(A), Optical fiber cable,770.3, 830.47(C). 300.5(D)and(J) 392.6(]) 770.12,770.26, 820.133,820.115454, 830.100(A)(6),830.157 Wireways,376.12(l), CATV coaxial cable, , 0, 770.154,770.182 Optical fiber cables, 378.12(1) 820.182 Definition,770.2 770.1W(A)(5) Protective devices,see Arc-fauit Pliable,362.2 Cellular concrete floor,see Cel- Radio and television re- circuit interrupters;Cir- Rigid metal conduit(Type tutor concrete floor race- ceiving station, cuit breakers;Fuses; RMC),see Rigid metal ways 810.21(D) Ground-fault circuit in- Cellular metal floor,see Cellular conduit(Type RMC) Cords,flexible,400.8(7), lerrupters;Overcurrent Rigid polyvinyl conduit(Type 400.14,640.45 protection metal floor raceways PVC),see Rigid polyvi- Critical operations power sys- Protective equipment,see Guard- Communications circuits, nyl chloride conduit tams.708.1O(C)(1) 800.110,800.133(A)(1),ing,guards 8{)0,[54 80{}.182 (Type PVC) Electrical metallic tubing. Protector,communications sys- , Secured,300.11(A) 358.12(1) tems,see Communica- Conductors in service,230.7 Service,see Service raceways Continuity,300.10,300.12 Electrical nonmetallic tubing, tions circuits Signaling Class I circuits. Cords,flexible,installed in, 362.12(10) Public address systems,Art.640 725.48,725.51 Electric signs,neon tubing in, Emergency power systems, 400'14 Strut-type channel,see Strut- 600 Definition,Art. 100-1 .41(D) 700.1 FPN 3 type channel raceway 53 230 22 225 Drainage, . , . Emergency system, Public assembly places,Art.518 Support For nonelectrical equip- 517.30(C)(3) Emergency lighting system. Electrical metallic tubing(Type ment,300.11(B) Lamps,electric discharge Art.700 EMT),see Electrical Supporting conductors,vertical, lighting,410.145 Pull boxes,see also Boxes;June- metallic tubing(Type 300.19 Lighting track,410.151(C)(1) tion boxes EMT) Surface metal,see Surface metal Liquidtight flexible metal Accessibility,314.29 Electrical nonmetallic tubing raceways conduit, 350.12(1) Construction specifications, (Type ENT),see Electri- Surface nonmetallic,see Surface Liquidtight flexible nonmetal- 314.72,314-111 cal nonmetallic tubing nonmetallic raceways lic conduit,356.12(1) Gutters,auxiliary,used as, (Type ENT) Underfloor,see Underfloor race- Luminaires,410.10(E), 366.58(B) Emergency circuits,indepen- ways 501.130(A)(2), Nonmetallic wireways used as, dent,700.9(B) Underground, 300.5,300.50 502.130(A)(2) 378.23(B) Equipment grounding conductor Wireways,see Wireways,metal; Metal-clad cable,300.42, Over 600 volts,314-IV installation,250,120(A) Wireways,nonmetallic 330.12 Sites Expansion joints,250.98, Wiring,exterior surfaces of Mineral-insulated metal- 4 AWG and larger conduc- 300.7(B),352.44 buildings,225.22 sheathed cable, tors,314,28(A) Exposed to different tempera- Radiant heating panels and radi- 332.1000) 6 AWG and smaller conduc- tures,300.7 ant heating sets,see Multioutlet assembly, tors,314.16 Flexible metal conduit(Type Fixed electric space- 380.2(B)(2) Over 600 volts,314.71 FMC),see Flexible heating equipment Nonmetallic-sheathed cable, Pumps,see also Fire pumps metal conduit(Type Radio and television equipment, 334.15(B) Canned,Class I hazardous(clas- FMC) Art.810.see also Com- Open conductors and cables, sifted)locations. Flexible metallic tubing(Type munity antenna televi- 230.50(B)(2) 501.15(F)(3), FMT),see Flexible me- sion and radio distribu- Open wiring,398.15(A), 505.16(E)(3) tallic tubing(Type tion(CATV)systems 398.15(C) Grounding,water pumps, FMT) Amateur transmitting and re- Overcurrent devices, 250.112(L), 250.112(M) Grounding,250.132,250-IV ceiving stations, 810-II1 240,24(C),240.30(A) Pool Short sections,250.86 Ex.2, Community television antenna, Raceways,300.5(D)(4), Double insulated,680.21(B), 250.132 810.4 300.50(B) 680.31 Induced currents,300.20 Definitions,810.2 2008 Edition NATIONAL ELECTRICAL CODE 70-513 Radio and television equipment INDEX Interior installation-transmit- Marinas and boatyards,555.19 Recreational vehicles(camping Reinforced thermosetting resin ling stations,810-1V Maximum curd-and-plug- trailers,motor homes, conduit(Type RTRC), Noise suppressors,810.5 connected load to, park trailers,travel Art. 355 Receiving equipment 111 antenna 210.21(B)(2),Table trailers,truck camp- Bends,355,24, 355.26 systems,810-I1 210.21(B)(2),210.23 ers),Art.551 Bushings,355.46 Radiographic equipment,see Minimum ratings,406.2(8) Alternate power source,restric- Construction,Art.355-111 X-ray equipment Mobile homes, 550.13 tion,551.33 Definition,355.2 Railway conductors,power and Mounting,406.4,406.80 Appliance accessibility and far- Grounding, 355.60 light, 110.19 Nungrounding-type,replace- tening,551.57 Installation,355-i1 Rainproof went,250,130(C), Attachment plugs,551.20(F), Joints and expansion fittings, Definition.Art. 100-1 406,3(D) 551.46(C) 355.44, 355.48 Raintight Nonmetallic extensions,382.42 Banding,551,55(B),551.56 Listing,355.6 Definition,Art. 100-1 Outdoor,see Outdoor Branch circuits,551.42,551.43 Marking, 355.120 Ranges,422.16(B)(3),422.33(B); receptacles Calculation for loads,551.42(D) Number of conductors, 355.22 see also Cooking unit, Outlets,210,50 Combination electrical sysiems, Securing and supporting, counter-mounted; Ov- Definition,Art. 10(-I 551,20,551-11 355.30,Table 355,30 ens,wall-mounted Dwellings,where required. Conductors,551.48 Size,355,20 Branch circuits, 210.19(A)(3) 210,52 Connections Splices and taps,355.56 Calculation of load, 220.55. Loads,220.14 Grounding,551.54,551.55 Trimming, 355.28 Table 220.55 Patient bed location,517.18(B), Power supply.551.46 Uses not permitted,355.12 Conductors,210.19 517.19(B) Splices and terminals,551.50 Uses permitted,355.10 Maximum load. 220.18 Ratings for various size circuits, Definitions,551.2 Relays Feeders,calculation of load, 210.21(B)(31,Table Distribution panelboard.551.45 Hazardous(classified)locations, 220.40,220.82(B)(1) 210.21(B)(3) Expandable units,connection, 501.105,502,150 Grounding,250.140 Recreational vehicles,551.52 551.47(P) Overload, motor Overcurrent Hoods,cord-and-plug connected, Replacement,406,3(D) Generator installations,551.30 protection,430.40 422.16(B)(4) Selected,health care facilities. Ground-fault circuit-interrupter. Reverse-current, transformers, Loads, demand factors and, 517.33iA) 551.40(C),551.41(C) 450.6(B) Table 220.55 Definition,517.2 Grounding,551.54,551.55 Remote control Mobile homes,550,15(E), Sensitive electronic equipment, Grounding conductor splices, Circuits,see Remote-control, 550.16(A)(1) 647.7 551.50 signaling,and power- Receptacles, 250.140 Ex. Show windows, in, 210.62 Identification of grounded con- limited circuits Rated load current,440.4(A) Stages and sets,530.21 ductor,551.49 Of induction and dielectric heat- Definition,4402 Swimming pools,680.22(A). Luminaires,551.53 ing equipment,6653 Reactors,see Resistors and 680 32 680 34 Multiple supply source,551.31 Switches,517.63(D) reactors 680.43(A),680.62(E) Other power sources,551.32 Remote-control,signaling,and Readily accessible,see Accessible, Tamper-resistant,4{Hs.[1 Outlet boxes.55 1.48 power-limited circuits, readily 250.11211),Art.725 Reaming,ends of metal conduits, Temporary installations, Overcurrent protection g 5904 D),590.6(A) Branch circuit,55[.43 Access to electrical equipment, . 342.28,344.28,358-28 ( 725.21 Re-bar electrodes,250.50 Ex., Terminals, identification, Distribution panelboard, 20010(B1 551.45 Class 1 circuits,725-II . 250.52(A)(2), Circuits extending beyond 25052(A)(3) Theaters,520.45 Power sources,other,551-111 one building,725.52 Receptacles,cord connectors, Voltages between adjacent de- Power supply assembly,551.44, Conductors,725.89 and attachment plugs vices,406.4(G) 551.46 P g Recessed luminaires 41 U-XI, Receptacles,551,2{)(F),551.41, Different circuits, 725 48 (caps),Art.406 410-Xir p SS1.S2 Extending beyond one Anesthetizing locations, building,725.52 517.64(F) Clearances,installation,410.116 Supply source 120-volt or Insulation,725.49(B) Branch circuits,210.7,210.52 Construction,410-XII 120/240-volt system, Number in raceways. Configurations.550.10(C). As raceways,410,64 551-IV 725.51 551.46(C),552.44(CI Temperatures,410.115 Switches,551.51 Critical branch,517.33(A) Wiring,410.117 System voltages,551-1V Overcurrent protection, 725.43 Definition,Art. 100-1 Recording systems,Art.640 Tags, labels,and marking, Size and use,725.49(AI Disconnecting means,422.33, Recreational areas,and dining 551.46(D) Locations,725.3,725.45 440,63 essential electrical sys- Tests,factory,551-V Overcurrent protection, Electrified truck parking space tems,health care racil- Wiring methods,551.47 725.43,725.45 supply equipment, ity,517.42(E) Recreational vehicle site Physical protection, 626.24(B),626.31(C) Recreational vehicle parks, Definition,551.2 725.31(B) Face later,406.4,406.5 551-Vt Supply equipment,551.71, P Power limitations,725.41 Grounding type,250.130(C). Calculated load,551.73 551.77 Wiring methods,725.46 250.146,406.3(A), Demand factors,Table 551.73 Definition,551,2 Class 2 and Class 3 circuits, 406.9,517.13, Definitions,551.2 Grounding,551.76 725--IIi 517.19(G) Disconnecting means,551.77(B) Recreational vehicle stand Applications of PLTC cables, Hazardous(classified) locations, Distribution system,551.72 Definition,551.2 725.154 501.145,502.145, Grounding,551.75,551.76 Refrigeration compressor motors Circuits extending beyond 503.145 Outdoor equipment, protection and controls,An,440 one building.725.141 Health care facilities,517.13, of,551.78 Refrigeration equipment,see Air- Conductors,725.130,725,143 517.18,517,19, Overcurrent protection,551.74 conditioning and refrig- Installation,725.133 through 517.61(B)(5),517(C)(2) Overhead conductors,clearance erating equipment 725.141 Insulated grounded terminals, for,551,79 Refrigerators,grounding,250.114 Interconnection of power sup- 350.146(D),517.16 Receptacles,551.71,551.81 Regulator bypass switch plies,725.121(B) Less than 50 volts,720.6,720.7 Underground wiring,551.80 Definition,Art, 100-1[ Listing,725-IV 70--814 NATIONAL ELECTRICAL CODE 2009 Edition INDEX Service equipment Locations,725.3 Construction specifications, Rotary phase converter Service-entrance cable(Types SE Marking,725.124,725.179 344--111 Definition,455.2 and USE),Art.338 Overcurrent protection,Chap. Couplings and connectors, Running threads,342.42(B), Bends,338.24 9,Tables I1(A)and 344.42 344.42(B) Branch circuits or feeders, II(B) Definition,344.2 338.10(B) Power sources,725.12](A), Dissimilar metals,344.14 Construction,338-I11 Chap.9,Tables I](A) Expansion fittings,300.7(B) Definition,338.2 and(B) Ferrous,300.6(A) -S- Grounding frames of ranges and Separation,725.136 Grounding,344.60 Safety,examination of equipment clothes dryers, Wiring methods Installation,344-I1 for,90.7 250.140 Ex. Load side,725.130 Listing,344.6 Screw shells Installation,338-1I Supply side,725.127 Marking,344.120 Identification Installation methods,for branch Classifications,definitions,725.2 Maximum number of conductors Polarity.200.10,410.50 circuits and feeders. Class 1,725-11 and fixture wires in. Terminals,200.10 338.10(B)(4) Class 2 and Class 3,725-I11 Tables C8 and C8(A) Lamphnlders,410-IX Marking,338.120 Definition,Art. 100-I Number of conductors,344.22. Sealable equipment Service-entrance conductors,Definition,Art. ]00-I Identification,725.30 Chap.9,Table 1 2304V,338.10(A) Mechanical execution of work, Reaming and threading,344.28 Sealing,see also Hazardous (clas- Uses not permitted,338.12 725.24 Size,344.20 permitted,sified)locations Uses 338.10 Motors,430-VI Splices and taps,344.56 Conduit systems,501.15, Service-entrance conductors, Overcurrent protection, Standard lengths,344.130 502.15,505.16,506.16 230-IV,338.10(A) 240.4fG),725.43, Supporting and securing, Intrinsically safe systems, Conductor sets,number of, 50470 23040 II(A)725.45. and I1(B) 344.30,Chap.9,Tables 314.23{E)and(F), Raceway seal,underground Considered outside of buildin 11(A) service 2348 g' , . Safety-control equipment. Uses permitted,344.10 230.6 725.31 Wet locations,344,10(D) Temperature changes, Definitions,Art. 100-1 300.7(A) Disconnecting eans,230-VI Remote machine room and Rigid polyvinyl chloride conduit Hermetically,500.7(7) g Y Drip loos 230.52 control room (Type PVC),Art.352 Definition,500.2 Insulation,230.41 Definition,620.2 Bends.352.24,352.26 Secondary ties,transformers, Remote machinery space and Bushings,352.46 Mounting supports, 450.6 Overcurrent protectionon,,23 230.90, control space Construction specifications, Sensitive electronic equipment, 230.91,230.92,230.208 Definition,620.2 352-III Art. 647 Over 600 volts,230-VIII Requirements for electrical Definition,352.2 Grounding,647.6 Physical damage,230.50 installations,Art. I10 Expansion fittings,300.7(B), Lighting equipment,647.8 Service head,230.54 Residential occupancies,see 352.44,Table 352.44 Receptacles,647.7 Size, 230.42 Dwellings Grounding,352.60 Single-phase supply system, Splices,230.46 Resistance Installation,352-1I 647.3 Underground,300.5(D)(3) AC resistance and reactance, Joints,352.48 Three-phase supply system, Definition,Art.100-1 cables.Chap.9,Table 9 Listing,352.6 647.5 Conductor properties,Chap.9, Marking,352.120 Wiring ethods,647.4 Wiring methods,equipment, Table 8 Maximum number of conductors g Service-entrance equipment,see Separable power supply cable Service equipment Heating elements,see Fixed and fixture wires in, assembly,626.25 Service equipment,230-V electric heating equip- Tables C9 through Definition,626.2 Definition,Art. 1004 ment for pipelines and C12(A) Separately derived systems, Disconnecting means,230-VI vessels Number of conductors, 352.22 250.20(D), 250.21(A), Connections,supply side, Of rod•pipe,and plate elec- Schedule 80,300.5(D)(4), 250.28(D), 250.30, 230.82 trodes,250.56 300.50(B),55 1.80(B 250.35(A) Connections to terminals, Welders,630-111 Securing and supporting,352.30 Definition,Art. 100-1 230,81 Resistors and reactors,Art.470 Size,352.20 Grounding electrode conductors. Electrically operated. Combustible material,on,near. Splices and taps,352.56 250.169 230.94 Ex. 6 470.3,470.18(C) Supporting and securing,Table Metal piping and frames,bond. Grounded conductor,discon- Conductor insulation,470.4 352.30 ing of,250.104(D) nection of,230.75 Hazardous(classified)Class II Trimming ends, 352.28 Portable generators,702.10(A) Ground-fault,protection at, locations,502.120 Uses not permitted,352.12 Surge protective devices,con- 230.95,705.32 Location,470.2 Uses permitted,352.10 nection of,285.24(C) Grounding electrode conduc- Over 600 volts,470-II Road show connection panel, Service cables,see also Service- for installation. General,470.18 520.50 entrance cable(Types 250,64(D) Grounding.470,19 Rod electrodes,250.52(A)(5). SE and USE! Indicating,230.77 Oif-filled reactors,470.20 250.53, 250.56, Definition,Art. 100-I Location,230.70(A) Space separation,470.3 250.66(A),250.70 Service conductors,see Conduc- Marking,230.66,230.70(B) Restaurants,service or feeder Roof decking,cables and race- tors,service Maximum number of discon- load,220.88 ways installed under, Service drops netts,six switch rule, Rheostats,construction specifica- 300.4(E) Clearances,230.24 230.71 tions,430.82(0) Roofs,conduits exposed to Connections,service head, Multiple occupancy buildings, Ride device sunlight on, 230.54 230.72(C) Definition,522.2 310.15(B)(2)(c) Definition,Art, 100-1 Over 600 volts,230.205, Rigid metal conduit(Type Room air conditioners,see Air Means of attachment,230.27 230,206 RMC),Art. 344 conditioners,room Minimum size, 230.23 Rating,230.79,230.80 Bends,344.24,344.26 Rooms,motion picture projector, Point of attachment,230.26. Simultaneous openings, Bushings,344.46 see Projector rooms, 230.28 230.74 Cinder fill,344.10(C) motion picture Supports over buildings,230.29 Six switch rule,230.71 2008 Edition NATIONAL ELECTRICAL CODE 70--815 Service equipment INDEX Suitable for use.230.70(C) Signaling circuits,see also Fire Snow melting,see Fixed outdoor Cellular concrete floor raceways. Guarding, 230.62 alarm systems;Remote- electric deicing and 372,12 Industrial control panels as, control,signaling-and snow-melting equipment Cellular metal floor raceways, 409.108 power-limited circuit., Solar cell 374.6 Mobile homes/manufactured Critical operations power sys- Definition,690.2 Concealed knob-and-tube, homes,550.32 tems,70M.14 Solar photovoltaic systems, 394,56 Motor control centers as,430.95 Definition,Art. 100-1 Art.690 Conduit bodies, 300.15, Overcurrent protection,230-VII Health care facilities,517-VI AC modules.690.6 314.16(0)(2) Accessibility,240.24(A) Installation requirements,Art. Circuit requirements,690-11 Construction sites,590,4(6) Location,230.91,230.92 725,Art.760 Circuit Siang and current,690.5 Deicing and snow-melting, Over 600 volts,230.205 Signals for healed appliances, Connection to other sources, 426.24(B) Relative location,230.94 422.42 690--VII Electrical metallic tubing, Specific circuits,230.93 Sign body Definitions,Art, 100-1,690.2 355.56 Ungrounded conductors, Definition,600.2 Disconnecting means,690-111 Electrical nonmetallic tubing, 2.10.90(A) Signs Ground-fault protection,690.5 362,56 Over 600 volts,metal enclosed Discharge,lighting,electric, Grounding,690-V Equipment grounding conduc- and metal clad equip- 410-Xlll,410-XIV Installation.690.4 tors,250.122(G) ment.490.47 Electric,Art.600 Marking,690-V1 Flat cable assemblies,322.56 Panelboards,405-111 Ballasts,transformers,and Maximum voltage,690.7 Flexible cords and cables,40).9, Service lateral electronic power sup- Overcuffent protection, 400,36 Delnition,Art. 100-1 plies,600.21 through 690.6(E),690.9 Flexible metal conduit,345.56 Service loads,calculations,Art. 600.24 Over 600 volts,690-IX Flexible metallic tubing,360.56 220,Annex D Bonding, 600.7(13) Stand-alone systems,690.10 General provisions, 110.14 Service point Branch circuits,600.5 Storage batteries,690-VIII High density polyethylene con- Definition.Art. 100-1 Definitions,Art. 100-1,600.2 Wiring methods,690-IV duit,353.56 Service raceways Disconnects,600.6 Solderless(pressure)connectors Intermediate metal conduit, Conductors,others permitted in, Enclosures, 600.8 Definition,Art. 100-1 342.56 230.7 Field-installed secondary wir- Solidly grounded Liquidtight flexible nonmetallic Drainage,230.53 ing,600.12 Definition,Art. 100-1 conduit,356.56 Service head,230.54 Field-installed skeleton tub- Sound recording equipment, Messenger-supported wiring, Underground,230-111 ing,600-11 Art. 640 396,56 Services,An. 230 Applicability,neon second- Audio signal processing,ampli- Nonmetallic extensions,352.56 Definition.Art. 1(X}4 ary circuit conductors, fication,and reproduc- Nonmetallic underground con- Emergency systems separate 6(X).30,600.42(A) tion equipment,540.50 duit with conductors, service,7(XI.12(DI Grounding,250.112(G), Theaters,520,4 354.56 Farm,220-V 600.7(A),600.24(B) Space Reinforce thermosetting resin Ground-fault protection, 230.95 Listing, 600.3 Cabinets and cutout boxes, conduit,355.56 Insulation,230.22 Location, 600.9,600.10(D), 312.7,312.9,312.11 Rigid metal conduit, 344.56 Number,230.2 60(}.21,600.42(G), Climbing,see Climbing space, Rigid polyvinyl chloride con- Disconnecting means, 230.71, 60042(H) line conductors on poles duit,352.56 250.64(D) Markings,600.4 Lightning roils,conductor enclo- Space-heating cables,424.40. Service-entrance conductor Portable or mobile,600.10 surer,equipment, 424.41(D) sets,230,40 Section signs,600.4(0) 250.60,250.106 FPN Strut-type channel raceways, Overhead supply, 23011 Definition,6((}.2 No. 2 384.56 Over 600 volts, 23(}-V111 Exit,health care facilities, Outside branch circuits and Surface raceways,386.56, Supply to one building not 517.32(B).517,42(B) feeders,225.14 388.56 through another, 230.3 Mandated standby,701.9(A) Over 600 volts,separation, Underfloor raceways, 390.6 Two or more buildings, 250.32 Outline lighting,Art.600 110.33, 110.34 Underground,300.5(E), Underground,230-I11 Standby,702.8 Working,see Working space 300,50(0) Service stations,gasoline,see Warning,.tee Warning signs Space heating,fixed,see Fixed Wireways, 376.56,378.56 Motor fuel dispensing Site-isolating devices,547.9(A) electric space-heating Spray application,dipping,and facilities Definition,547.2 equipment coating processes, Setting for circuit breaker) Skeleton tubing 600-11 Spacing between bare metal Art.516 Definition,Art. 10(}-1 Definition,600.2 parts,408.56,Table Classification of locutions,516.3 Shielding,see Guarding,guards Smoke ventilator control,stage, 408.56 Definitions,516.2 Short-circuit current rating 520.49 Spas and hot tubs,680-IV Equipment,516.4,516.7,516.10 Definition,Art. 100-1. 110.10 Snap switches,see also AC-DC Definitions.680.2 Grounding,516,16 Surge protective devices,285.6 general-use snap Indoor installations,680.43 Wiring,516.4,516.7 Short-time duty switches Outdoor installations,650.42 Spray washers,high-pressure, Definition,Art. 1(WI Accessibility,grouping, Packaged equipment assembly 422.49 Showcases,wall cases,410.59 404,8(B) Definition,680.2 Spread or fire or products or Show windows Definition,Art. 100-I Protection,680,43,680,43(A)(2) combustion,see Fire Definition,Art. 100-1 Electric-discharge lighting over Special permission,see Permis- spread Flexible cords,400.11 1000 volts,410.147 sion,special Stage effect(special effect) Luminaires,410.14 Grounding,404.9(B) Spider(cable splicing block) Definition,530.2 Branch circuits,220,14(G) Motors,430,83(C), Definition,530.2 Stage equipment,theaters Feeders,220.40,220.431AI 430.109(A)(3). Splices and taps Fixed,520-III Receptacles,210.62, 430,109(C)(1) Antennas, 810.14 Portable,520.5(B),520-V 314.27(C) Ex. Mounting,404.10 Auxiliary gutters,366.56 Definition,520.2 Sidelights,borders,and prosee- Multipole,404.8(C) Cabinets and cutout boxes, Stage property nium,520.44 Ratings,404.14 312.8 Definition,530.2 7"16 NATIONAL ELECTRICAL CODE 2008 Edition INDEX Switches Stages,motion picture and televi- Supports,see subhead under on- Ground-fault circuit interrupters, Dry location,408.20 sion,530-11 tries for specific wiling 680.5 Easily ignitable materials,near, Definition,530.2 and equipment Fountains,680.51(A) 408.17 Stage set Suppressors,radio noise,810.5 Hydromassage bathtubs, Flash protection, 110.16 Definition,530.2 Surface metal raceways,Art. 386 680.71 Grounding frames and swc- Stairway chairlifts,Art.620; .see Combination raceways,386.70 Junction boxes for,680.24 tues. 250.112(A) also Elevators,dumb- Construction specifications, Luminaires,680.22(C)(4), Grounding instruments,408.22 waiters,escalators, mov- 386-I1I 680.23(A)(3).680.24(8) Guarding live parts, 110.27 ing walks,platform lilts, Definition,386.2 Pool covers,680.27(B)(21 Illumination, 110.26(D) and stairway chairlifts Grounding,386.60 Pool pump outlets,680.22(B) Installation,indoor and outdoor. Stand-alone system Installation,38641 Receptacles,680.5,680.6, 110.26 Definition, 690.2 Listing,386.6 680.22(A)(4),680.32, Instruments,meters,and relays Standby systems,see Emergency Number of conductors or cables, 680.43(A),680.44, on,250,174 systems;Legally re- 386.22 680.57(B),680.58, Location,408.16,408.17, quired standby systems: Securing and supporting.386.30 680.62(E) 408.20 Optional standby Size of conductors, 386.21 Signs,680.57(B) Portable,theater stages,520-IV systems Splices and taps. 386.56 Spas,hot tubs,680.43, Stage,520-I1,520-IV Static phase converter Uses not permitted,386,12 680.44 Support,busbars,conductors, Definition,455.2 Uses permitted, 386.10 Storable pool equipment, for, 408.3 Steel,structural,bonding, Surface nonmetallic raceways, 680.32,680.33(B)(3) Working spaces about, 110.26 250.104 Art.388 Therapeutic pools,680.62(A), Switches,Art.404.see also Haz- Steel siding, 250.116 FPN Combination raceways,388.70 680.62(E) ardour(classified)loca- Storage batteries,Art.480 Construction specifications, Wiring to,680.24(8) lions;specific types of Aircraft hangars,513.10(B) 388-III Grounding,680.6.680.7(B), switches Charging equipment,503.160 Definition,388.2 680.23(B)(3)and(F)(2), Accessibility and grouping, Critical operations power sys- Grounding,388.60 680.24(D),680.24(F), 404.8 tems,708.20(E) Listing,388.6 680.25(B),680.43(F), AC-DC general use snap Definition,480.2 Marking, 388.120 680.54,680.55, switches,.see AC-DC Disconnecting means,480.5 Number of conductors or cables 680.57(E),680.62(D) general-use snap Electric vehicle nonvented in,388.22 Heaters and heating equipment switches Definition.625.2 Securing and supporting,388.30 Deck area heating,680.27tC) AC general use snap switch, Emergency systems, 700.k2(A). Size of conductors, 388.21 Paul water heaters,680.9 403.14 700.12(B)(4) Splices and taps,388.56 Hydromassage bathtubs, Air-conditioning and refrigerat- Garages,511.10 Uses not permitted.388.12 680-VI,680-VII ing equipment 440-II Installation, 690.71 Uses permitted,388.10 Junction boxes and enclosures, Appliances,422.34,422.35 Insulation,480.6.480.7 Surfaces,exposed conductive 680,23(C),68024 Bypass isolation,700.6(8), Locations,480.9 Definition,517.2 Lighting,411.4(B),680.22(Ch YP 701.7(B) Overcutrent protection for prime Surge arresters,see Lightning 680.23.680.26(13)(4), Definition,Art. 100-I movers.480.4 (surge) arresters 680.33,680.43(B), Circuit breakers used as, Racks and trays.480.8 Surge protection,see Lightning 680.51,680.62(F), 24083(D) Solar photovoltaic systems, (surge)protection 680.72 690-VIII Surge protective devices(SPI)s), Overhead conductor clearances, Definitions,Art. lUU-I Sound recording equipment, Art. 285,501.35,502.35 680.8 Devices over 600 volts 640.9(B) Conductor routing,285.12 Permanently installed,680-11 In busways,368.239 Vents,480.10 Connection,285-III Receptacles,location and pro- Definition,Art. 100-11 Structures Definition,Art. 100-1 tection.680.22(A), Dimmer,see Dimmers Definition, Art. 100-1 Installation,285-II 680.32,680.34, Disconnecting means Strut-type channel raceway, Listing,285.5 680.43(A),680.62(E) Appliances,422-111 Art.384 Location.285.11 Spas and hot tubs,68()-IV Motors,controller,430-IX Construction specifications, Number required, 285.4 Storable,680-III Services,230-VI 384-111 Short circuit current rating. Definition,680.2 Emergency systems,700-V Definition,384.2 285.6 Switches and switching devices, X-ray equipment,517.72, Grounding,384.60 Uses not permitted,285.3 680.22(D),680.41 660-11 Installation, 384-II Swimming pools,fountains,and Therapeutic pools and tubs, Enclosures,installation in, Listing,384.6 similar installations, 680-VI 404.3•404.12,404.18, Marking, 384.120 Art.680 Transformers,680.23(A)(2), 450.8(0) Number of conductors, 384.22 Approval of equipment,680.4 680,24(B) Essential electrical systems, Securing and supporting,384.30 Bonding,680.26,680.42(B), Underwater audio equipment, transfer switches, Size of conductors,384.21 680.43(D),680.53, 680.23 517.41(B) Splices and taps,384.56 680.57(E),680.62(B), Underwater luminaires,680.23, General-use,Art.404 Uses not permitted.384.12 680.62(C),680.74 680.26(B)(4),680.33, Definition,Art. 100-1 Uses permitted,384.10 Ceiling fans.680.22(C), 680.43(B)(2) Identification, 110.22 Submersible equipment,680.51 680.43(B) Switchboards,Art.408 Indicating,404.7,422.35, Substations Curd-and-plug-connected equip- Clearances, 110.26,408.5, 424.21 Motion picture and television ment,680.7, 408.18 Interrupter studios,530-VI 680.21(A)(5), Combustible material,location Definition,Art. 100-11 Over 600 volts,490-III 680.22(C)(5),680.31, relative to,408.17 Isolating,501.115(B)(2) Supervisory control and data 680.42(A)(2),680.56 Conductor insulation,408.19 Capacitors,over 600 volts, acquisition(SCADA), Deck area heating,680.27(0) Construction specifications. 460,24(B) Annex G Definitions,680.2 408-IV Definition,Art. 100-1 Support fittings fill, boxes, Fountains,680-V Damp or wet locations,408.16 Motors over 100 HP, 314.16(B)(3) Drinking fountain,422,52 Definition,Art. 100-1 430.109(E) 2W8 Edition NATIONAL ELECTRICAL CODF 70-817 Switches INDEX Services,over 600 volts. Conductor,three single- Bulk storage plants,electrical Classification of maximum 225.51,230.204 insulated in under- area classifications, surface temperature of Knife,see Knife switches ground electrical ducts, Table 515.3 Group II equipment, Limit,cranes and hoists,610.55 over 2000 volts,Table Cable markings,Tables 725.179, Table 505.9(D)(1) Manually operable,Art.404 310.78 760.176(G).760.179(I), Gas classification groups, Motor-circuit Crane and hoist motor con- 770,113 Table 505.9(C)(1)(2) Definition,Art. 100-1 ductors,Table Cable substitutions.725.154, Minimum distance of ob- Motor controllers,430-VQ 610.14(A) 760.154(D),770.154(E), structions from flame- Panelboards,408.36(A),408.39 Fixture wire,Table 402.5 820.154(E),830.154 proof flange openings, Regulator bypass Flexible cord,Table 400.5 Cable trays,grounding,Table Table 505.7(D) Definition,Art. 100-11 General conductors.0 392.7(B) Types of protection desig- Remote-control,517.63(D) through 2000 volts Cable fill,Tables 392.9, nation,Table Service, 230-VI Aluminum,copper,or 392,9(E),392.9(F), 505.9(C)(2)(4) Signs,outline lighting,600.6 copper-clad aluminum, 392.10(A) Insulations,Tables 310.13(A) Snap,see Snap switches single-conductor in free Cable trays,wiring methods, through 310.13(C) Theater dressing rooms,520.73 air,Tables 310.17, Table 392.3(A) Maximum number in,Annex Transfer,see Transfer switches 310.19 Calculation of feeder loads by C Tables Tunnels, 110.55 Aluminum,copper,or occupancies,Table Electrical metallic tubing, Unit,appliances,422.34,422.35 copper-clad aluminum. 220,42 Tables C1 and C1(A) Switchgear,metal-enclosed, two or three single- Conductors Electrical nonmetallic tub- insulated conductors 110.34{F),230.211, Adjustment factors for more ing,Tables C2 and 490111 supported on messenger, than three current- C2(A) Definition,Art. 1U0-1 Table 310.20 carrying conductors in Flexible metal conduit, Aluminum,copper,or raceway,cable,Table Tables C3 and C3(A) copper-clad aluminum B.310.11 Intermediate metal conduit, in raceways or cables Application.Tables 310.13(A) Tables C4 and C4(A) -T- types AC,NM,NMC through 310.13(C). Liquidlight flexible metal Tables,Chap.9,Annex B , SE,Tables 310.16, 402.3 conduit.Tables C7 and Annex C 310.18 Clearances,conductors enter- C7(A) AC resistance and reactance Bare or covered conduc- ing bus enclosures, Liquidtight flexible nonme- cables,Chap. 9,Table 9 tors,Table 310.21 408.5 tallic conduit,C6, Ampacities Multiconductor cables, Clearances, services,Table Tables C5 through Amusement attraction con- types TC, MC,and MI 230.51(C) C6(A) ductors,Table 522.22 in free air,Table Conduit and tubing fill for, Rigid metal conduit. Cable insulated,over 2000 B.310.3 Annex C Tables Tables C8 and C8(A) volts Three-conductor cable in Deflection,minimum bending Rigid nonmetallic conduit, Three-conductor aluminum raceway in free air, space in cabinets,cutout Tables C9 through in isolated conduit in Table B.310.1 Three insulated conductors boxes,312.6(B),Tables C12(A) air,Table 310.76 312.6(A) Metal boxes, number in, Three-conductor aluminum in cable in underground electrical ducts,Table Dimensions Table 314.16(A) in underground ele0.8 8.310.6 Compact aluminum build- Minimum size of,Table cal ducts,Table 310.80 Three-conductor aluminum Three single-insulated con- ing wiring.Chap.9 310.5 ductors directly buried Compact copper and alu- Over 2000 to 35,000 volts isolated in air,Table in earth,types UF,USE, minum building wiring, Ampacities,Tables 310.81 310.72 Table 5A through r Table 8.310.10 g 314.86 Three-conductor copper Three single-insulated con. Insulated conductors,and Properties,Chap,9,Table 8 cable in isolated conduit ductors in nonmagnetic fixture wires.Chap.9, Support, vertical raceways, in air,Table 310.75 underground electrical Table 5 300.19(A) Three-conductor copper in ducts,Table B.310.5 Rubber,thermoplastic- Volume required per con- underground electrical Three single-insulated con- covered,Chap.9, ductor,Table 314.16(B) ducts,Table 310.79 ductors in undetground Table 5 Conduit or tubing Three-conductor copper electrical ducts,Table Fixture wires,Table 402.3, Combination of conductors, isolated in air,Table B.310.7 Chap.9,Table 5 percent area fill,Chap. 310.71 Three triptexed single in- Flexible cords and cables, 9,Table l Triplexed or three single- sulated conductors di- types,Table 4W.4 Conduit and tubing fill,for conductor aluminum in rectly buried in earth Grounding,size conductors and fixture isolated conduit in air, (UF and USE cables). For AC equipment,Table wires,Annex C Tables Table 310.74 Table B.310.9 250.122 Dimensions,Chap, 9,Table 4 Triplexed or three single- Two or three insulated For grounded systems, Expansion characteristics, conductor aluminum in conductors cabled Table 250.66 Table 352.44 underground electrical within an overall cover- Hazardous(classified)loca- Flexible metal (trade size i/s), ducts,Table 310.77 ing directly buried in tions,Classes 1,11,and Table 348,22 Triplexed or three single- earth,Table B.310.8 III,Divisions 1 and 2 Number of conductors in. conductor copper in Wound-rotor secondaries, Classification of maximum Annex C Tables isolated conduit in air, Table 430.23(C) surface temperature, PVC rigid nonmetallic,ex- Table 310.73 Bare metal parts,spacings be- Table 500.8(C) pansion characteristics, Conductor,single-insulated, tween switchboard and Class III temperatures, 352,44 isolated in air,over panelboard,Table Table 500.8(D)(2) Supports,Tables 2000 volts 40856 Hazardous(classified)loca- 344.30(B)(2). 352.30(B) Aluminum,Table 310.70 Branch-circuit requirements, tions,Class 1,Zones 0, Construction,types of,Annex E Copper,Table 310.69 Table 210.24 1,and 2 Tables W"18 NATIONAL ELECTRICAL CODE 2008 Edition INDEX Thermally protected (thermal protection) Cooking appliances,demand Locked-rotor,code letters, Tamperproof receptacles,see Receptacles,590.4(D).590.6(A). factors and loads,Tables Table 430.7(B) Receptacles 590.6(8) 220.55,Table 220.56 Locked-rotor current conver- Taps,see also Splices and taps Services,590.4(A) Electrified truck parking space Sion,Tables 430.251(A) Branch circuit,210.19(A) Splices,590.4(G) feeder/service load cal- and(B) Busways,368.17(C)Ex. 1 Terminations at devices,590.4(1) culations.Table Maximum rating or setting. Equipment grounding conduc- Time constraints,590.3 626.11(BI branch-circuit protective tors.250,122(G) Terminal housings Farm load, method for comput- devices.Table 430.52 Feeders,see Feeders,laps Generator,445.17 ing,Tables 220.102, Maximum rating or setting. Grounding electrode conductors, Motor,430.12 220,103 control circuit overcur- 250.64(D)(1) Grounding through, Fixture wires rent protective device, Luminaires.410.117(C) 430.245(A) Conduit and tubing fill for, Table 430.72(B) Overcurrent protection,240.21. Phase converters,455.10 Annex C Tables Minimum spacings between 240.92(B) Terminals Maximum number in bare live parts,motor Remote-control circuit%. 725.45 Connections to, 110.14,250.8, Electrical metallic tubing, control centers,Table Separately derived systems, 250.68 Tables CI and CI(A) 430.97 250.30(A)(4) Electric discharge tubing,signs. Electrical nonmetallic tub- Number and location,over- Service-entrance conductors, etc.,600.42 ing,Tables C2 and load units,Table 430.37 230.46 Identification C2(A) Other articles,Table 430.5 Task illumination,517.33(A) Flat conductor cable, Flexible metal conduit, Secondary ampacity,Table Definition.517.2 322.120(C) Tables C3 and C31A) 430.23(C) Telecommunications equipment, Motors,controllers,430.9(A) Intermediate metal conduit, Terminal,spacing and hour- 800.18,800.170;see Polarity,200.9 through Tables C4 and C4(A) 200.11 ing,Tables 430.I2fB1, also Communications Liquidlight flexible metal 430.12(C)(1), cifeuits Wiring device,250.126 conduit,Tubles C7 and Tests 430.12(C)i2) Telegraph systems,see Cammuni- C7(A) Emergency systems,700.4 Multifamily dwellings,optional cations circuits Liquidlight flexible nonme- calculation demand fac- Telephone exchanges,circuit Ground-fault protection, tallic conduit,Tables C5 tors,Table 220.84 load,220.14 Ex. 230.95(C) through CNAI Insulation resistance,space heat- Rigid metal conduit, ing cables,44.45 communications systems cations circuits Tables C8 and CS(A) Rigid polyvinyl chloride Cable substitution,Table Television and radio distribution Legally required standby sys- tems,70L5 conduit,Tables C9 Luminaires,410.85 through CI_(A) Cover requirements,Table nity antenna television � Mobile homes,550.17 830.47 and radio distribution General fighting loads 2 .12 Limitations,Table 830.15 1CATV)systems Park trailers,vehicles,pansies.Table 220.12 Recreational vehicles,551.60 Household clothes dryers,de- Optional calculations,three or Television equipment see Radio 'theaters,Art.520 mand loads,Table more multifamily units, and television Audio signal processing,520.4 2 20.54 Table 220.84 equipment Branch circuits,520.9 Household ranges and similar Radio and TV equipment,an- Television studios,Art.520, tenna sizes Art 530 Conductors,number in raceway, . cooking appliances,de- 520.6 Amateur stations,Table Temperature controls mane 5 and loads, 810.52 Boilers,overtemperature limit Definitions, , 220.55 5 Table 220.5 Dressing room,520-VI Receiving stations,Table control,424.73,424.83 Live parts, separation Emergency systems.Art.700 Minimum distance from 810.INA) Fixed electric heating equipment Grounding. 520-VII fence to live parts, Rating factors for power resis- for pipelines and ves. Fixed electric equipment. Table 110.31 tors.Table 430.29 sell,427.56 250.112(F) Over 600 volts Recreational vehicle park de- Fixed outdoor electric deicing Live parts.520.7 Air separation,Table mand factors,Table and snow-melting P,rrlahle equipment,520.10 490.24 551.73 equipment,426,51 Stage equipment Elevation,Table 110.34(E) Restaurants,optional method Motor overlemperature pro[ec- Fixed,52(1--I1 Working space,Table load calculation.Table tion,430.126 Portable,520-V 110.34(A) 220,88 Temperature limitations Switchboard Working clearances,Table Schools,optional method load Conductors,310.10 Fixed,520-Il 110.26(A)(1) calculation,Table Nonmetallic raceways and tub- Portable,520-IV Mobile home park demand fac- 220.86 ing,see subhead under Wiring methods,520.5 tors,Tuble 550.31 Support services,Table entries for specific race- Therapeutic equipment, Motor fuel dispensing facilities 230.51(C) way or tubing type 517.73(B) Class 1 locations,Table Transformers,medium and high In outlet boxes for luminaires Therapeutic high-frequency di- 514.3(B)(1) voltage,Tables (fixtures),410.21 athermy equipment Electrical equipment classi- 450.3(A),450.3(B) Service-entrance cable, Definition,517.2 lied areas,Table Underground wiring,minimum 338.10(B)(3) Therapeutic pools and tubs, 514.3(B)(2) cover,Tables 300.5, Temporary installations,Art. 590 680-VI Motors Table 300.50 All wiring installations,590.2 Definitions,680.2 Conductor rating factors for Wire-bending space,minimum. Branch circuits,590.4(C) Thermal devices power resistors,Table Tables 312.61 A), Disconnecting means,590.41E) Overcurrent protection,240.9 430.29 312,6(B) Feeders, 590.4(B) Thermally protected(thermal Duty cycle service,Table Tamperability Ground-fault protection,590.6 protection) 430.22(5) Circuit breakers,nontamperable. Guarding over 600 volts,590.7 Definition,Art. 100-1 Full-load currents,Tables 240.82 Lamp protection,590.4(F) Fixtures,recessed,410.115(0) 430.247 through Type S fuses,nontamperable, Protection from accidental Fluorescent lamp ballasts in lu- 430.250 240.54(D) damage,590.4(H) minaires,410.130(E) 2008 Edition NATIONAL ELECTRICAL CODE 70419 Thermally protected (thermal protection) INDEX Luminaires,recessed, Hazardous(classified)Class II Transmitting stations,radio and Underground feeder and branch- 410,115(C) locations,control trans- television,810-III circuit cable(Itype Thermal protector formers at,502.120 Transport refrigerated unit UF),Art, 340 Definition,Art. 100-1 Installations,indoor and out- (TRU),626-III Ampacity,340.80 Thermal resistivity,310.60, door,450.21 through Definition,626.2 Bending radius,340.24 8.310.15(13)(2) 450.27 Travel trailer,see also Park Conductors,340.104 Three overload units,motors, Instrument,grounding,250-IX trailers Construction specifications, Table 430.37 Connections at services, Definition,551.2 340-I11 Tools 230.82(4) Trays,storage batteries,480.8(B) Definition,340.2 Double insulaled, 250.114 Ex. Isolation Trees,luminaires(lighting fix- Equipment grounding conductor, Metal working machine,see Definition,517.2 tures)supported by, 340.108 Industrial machinery Electric deicing,snow- 410.360 Installation, 340-II Motor-operated,hand-held, melting equipment, Truck camper;see also Recre- Insulation,340.112 �ruuuding• 426 3l ational vehicles Sheath,340.116 25(!,114(31{c). Electric pipeline,vessel heat- Definition,551.2 2 P�Pe Uses not permitted,340.12 50.114(4)(c) ing equipment,427.26 Truck coupler Uses permitted, 340.10 Track lighting,.see Lighting track Health care facilities, Definition,626.2 Underground installations,see Trailers,types of,see also Park 517.19(F),517.20, Truck flanged surface inlet, Manholes:Tunnels: trailers 517.63(E),517.63(F), 626.25(B)(4) Vaults Definition,551.2 517.76,517,160(A)(4) Definition,626.2 Underground service-entrance Transfer switches Trucks Less-flammable liquid-insulated, cable(USE),see Critical operations power sys- Definition,626,2 4SU.23 terns,708.24 Service-entrance cable Location,accessibility,450.13 Electrified,parking space equip- (Types SE and USE) Definition,Art. 10(YA Marking,450.11 ment,see Electrified Underground wiring,and US see Emergency systems,7(10.6 Modification of,450.28 truck parking space also Hazardous 5;see cell systems,692,59 equipment Motor control circuit,430.72(C) fied) locations Legally required standby sys- Tubing,see also Conduits Nonflammable nuid-insulated, Aircraft hangars,513.8 [ems,701.7 Definitions,600.2 g 450.24 Ampacities. 310.60(C)(2), Optional standby system:,,702.6 Electrical metallic,see Electrical Oil-insulated 'fables 310.77 through Transformers,Art.450,see also metallic tubing g 26 450 Indoors, . 310.85 Hazardous!classified) Electrical nonmetallic,see Elec- Outdoors,450.27 Bulk storage plants,515.8 locations Outdoors, 450.3 tricot nonmetallic tubing g P Arnuwment attractions, Overcurrent P Electric discharge,signs,etc., Buried conductors,Types USE, 522.10(A)(1) through 450.5 600.41 UF, 340.10 Power-limited and signaling cir- Conductor types in raceways, Are welders,630-11 Power-limited metallic,Art YPe'.360. see Askarcl-insulated.450.25 cuits,remote control, Flexible metallic tubing 310.7 Audio,see Audio signal pro- 725.41,725.41(A)(1), Tunnels Dry and damp locations, cessing,amplification, 725.45(D) Access, 1 10.76 3I0.8(B) and reproduction Remote control circuits for, Installations over 6W volts, Earth movement and,300.5(1) equipment 430.75(B),725.41, nominal, I10-IV Intermediate metal conduit, Autotransformers,430.109(D), 725.41(A)(1),725.45(D) Ventilation, 110.57, 110.77, 342.10(B)and(C) 450.4 Research and development, 110.78 Liquidtight flexible metal Audio,640.91D) 450.1 Ex.8 TV,see Radio and television conduit, 350.10(3) Definition, 640? Secondary ties,450.6 equipment Minimum cover requirements, Ballast for lighting units, Signs and outline lighting, Two-fer,520,69 3W.S(A) 410.138 600.21.600.23.6W.24 Definition,520.2 Motor fuel dispensing Facilities, Branch circuits,210.9 Solar photovoltaic systems, 514.8 Feeders,215.11 690.9(B) Over 600 volts, 300.50 Grounding,450.5 Specific provisions,450--II _U_ Protection of, 300.5(D),300.5(1) Motor starting, 30.82(B), Swimming pools, Fountains,and Raceways,service,250.84 g� Underfloor raceways,Art. 39p 430.1 09(D) similar installations, Conductors Reinforcin g termosettin g resin Ca acitom Art,460 680.23(A)(2),680.24(B) Ampacity,390.17 conduit,355.1o(G) Installation,Art.450 Terminal wiring space,450.12 Number in raceway,390.5 Rigid metal conduit,344.10 X-ray equipment S 17.76, Tunnels, 110.55 Size of,390.4 Rigid polyvinyl chloride 660-111 Two-winding, underwater light- Connections to cabinets,wall conduit,352,10(G) Definitions,450.2,551.2 ing.680.23(A)(2) outlets,390.15 Service cable,250.84 Dry-Iype,450.1 Ex. 2,450.8(B), Unused current transformers, Covering,390.3 Services,230-11I 450.21,450.22 short-circuiting of, Dead ends,390.10 "S"loops, 300.5(1)FPN Electric discharge lighting 110.23 Discontinued outlets,390.7 Splices and taps,300.5(E), systems Vaults,450-4II Inserts,390.14 300.50(C) More than 1000 volts, Ventilation,450.9 Junction boxes, 390.13 Swimming pools,680.10 410-XIV X-ray equipment,517.76, Laid in straight lines,390.8 Wet locations. 310.8(C) 1000 volts or less,410-XIII 660-III Markers,390.9 Ungrounded Elevators,dumbwaiters,escala- Transformer vaults,450-I1I Splices and taps,junction boxes, Definition,Art. 100-1 tors,moving walks, Doorways,450.43 390.6 Uninterruptible power supplies platform lifts,and stair- Drainage,450.46 Uses not permitted,390.2(B) (UPS),645.11, way chair lilts, Location,450.41 Uses permitted,390.2(A) 700.12(C),701.11(C) 620.13(C) Storage,450.48 Underground circuits,communi- Unit equipment,emergency and Fire pumps,695.5 Ventilation openings,450.45 cation,800.47 standby systems, Grounding,450.5,450.6(C), Walls,roofs,and floors,450.42 Underground enclosures, 110.59; 700.12(F),701,(1(G) 450.10 Water pipes and accessories, see also Manholes: Unused openings Guarding,450.8 450.47 Vaults Boxes and fittings, 110.12(A) 70-820 NATIONAL ELECTRICAL CODE 2008 Edition INDEX Working space Utility-interactive inverters,20113 Voltage and volts Solar photovoltaic systems. Wired luminaire sections, Ex.,705.12(D), Branch circuits,limits, 210.6 690.51C),690.10(C), 410.137(C) 705.30(D), 705-II Circuit 690.17 Wires,see also Conductors,Cords; Definition.Art. 100-1 Definition,Art. 101-1 Transformers,450.8(D) Fixture wires Hybrid systems,705.82 Drop Utility interactive inverters. In concrete footings,electrodes, Definition.705.2 Branch circuits,210.19(A) 705.12(D)(7) 250.52(A)(37 Output circuit,705.60(A)(2), FPN No.4 Water,natural and artificially Definition,800.2 705,65(A) Conductors. 310.15(AH I) made bodies of,see Wireways,metal,Art.376 Definition, 70.5.2 FPN No. 1 Natural and artificially Ampacities,376.22 Feeders,2I5.2(A)(3) FPN made bodies of water, Utilization equipment Construction specifications, Boxes No. 2 electrical wiring and 376-III Minimum depth of,314.24 Sensitive electronic equip- equipment for Dead ends,376.58 Outlet,314.27(E) ment. 647.4(D) Water healers,422.11(E), Definition,376.2 Definition,Art. 1170-1 Electric discharge lighting.410- 422.1 I(F)(3).422.13 Deflected insulated,376.23(A) X111,410-XIV Controls,422.47 Extensions,376,70 General provisions, 110.4 Nameplate load,220.82(C)(3) Installation,376-11 Ground, to Protection,422.11(E), Insulated conductors,376.23 -V- Definition. Art. 100-1 422.11(FI(3f Marking, 376.120 Vacuum outlet assemblies,cen- High Water pipe Number of conductors,376.22 tral,422.15 Definition,490.2 Bonding Imetal),250.104 Securing and supporting„376.30 Valve actuator motor(YAM) Less than 50,Art.720 Connections, 250.8,250.68(61 2 assemblies, Limitations,clevalor.,,dumb- Size es ad taps,conductors,0,56 2 As grounding electrode, Splices and taps,37fi.5G 430.102(A) Ex. 3 waiters, mov. 250.52(A)(I),250.53(D) Uses not permitted.376.12 Definition,430.2 g Watertight Vapors,flammable liquid- Low (H]-I U,,es permitted,376,10 Definition,Art. I reduced, see Hazard- Definition.551.2 Wireways,nonmetallic,Art.378 P Weatherproof ous(classified)locations Marking. 240.83(E) Definition,Art. lUO-I Nominal Construction specifications, Varying duty Welders,electric,Art. 630 378-111 Definition,Art. I(N)-I Definition,Art, 10x1-I 630-111 Arc,63(1-11 Dead ends,378.58 Vaults 110.71, 110.73. 110-V Nominal battery Definition,378.2 Access, 110.76 Definition,«18(1.2 Resistance, Deflected insulated,378'3(A) Capacitors,460.2 Over 600 vole Wilding cable,63(}-IV , Art,490 Wet locations,see also Damp or Expansion fittings,378.44 Film storage, 530-V Receptacles, s oltages between wet Ices al o Extensions,378.10(4).378.70 Service over 600 volt_.- 110.31, adjacen(.406.4(G) Conductors,types,locations 8(C). Grounding,378.60 230.212 Swimming pool underwater Installation,378-11 Service 600 volts or less, luminaires. 680.23(A)(4) Table 310.13(A) Insulated conductors,378.23 Control circuits in,522.28 230.673) Wiring methods,3(H}.2 Definition,Art. 1(x1-] Marking,375.120 Transformer-450-111 Electrical metallic tubing, Number of conductors,378„22 Ventilation, 110.77, 110.78 358e 0(CI Securing and supporting,375.30 Vehicles,see Electric vehicles; �V Electric signs and outline light- Size es and taps, 3 8.56 Wading pools Splices and to s 378.56 Recreational vehicles ing,600.9(D), s and Definition,b5(1.2 Uses not permitted.378.12 Vending machines,cord-and- 600.21(C).6W.42(G),Wall cases,410.59 Uses permitted,378.10 plug-connected,42_„.51 Wolf-mounted ovens,see Ovens. 60042(H1(2) Wiring integrity, 110.7 Ventilated Enameled equipment, 9 2 wall-mounted Wiring methods, 1 10.8,Art.300 Cable trays, 39�.91E1, 3),..10 3U0.6fA)fl) Warning signs(labels),al equip- Ducts,300.2 1,300.22 Definition,Art. Ill!)-I Gutters,sheet metal auxiliary, 2 meet,.see rrlsn Labels 2 Exposed Ventilating ducks,wiring,3(x}...1. 366.10(A)(.-I required 300.22 Health care facilities,517.20 Definition,Art. 10(1-1 Ventilating piping for motors, {} se Aircraft hangars,S13.7IF)• General requirements fur, e q 513.1 Intermediate metal conduit, etc.502.128,503.125 s 342.10(D) General requirements Electroplating.bond spraying, for wiring methods Ventilation Luminaires in,410.IUfA1. Electrostatic hand spraying, Aircraft hangars,513.3(D) 516.1U(A)f81 410.34(B) Hazardous iclassified) locations, Battery locations,480,9(A) Elevators,dumbwaiters,eccala- Mounting orequipment, see subhead under en- Equipment,general, 110.f 3(B) tors, moving walks. 300.6(D) tries for specific hazard- Garages,commercial,5I1.3(C1 platform lifts,and stair- Nonmetallic wireways, ous location involved Manholes, tunnels,and vaults, way chairlifts,620.3(A), 378.1 0(3) Health care facilities.517-II 110,57, 110.77, 110.75 62052(B) Raceways installed in locations intrinsically safe systems, Motor fuel dispensing facilities, Flash protection, 110.16 above grade.300.9 504.20 lubrication and service Fuel cell system6,692.1O(C), Recreational vehicle parks, Manufactured homes,550.10 rooms-without dis- 692.17,692.56, 551.78(A) Mobile home parks,550.10 pensing,Table 692.65(B) Reinforcing thermosetting resin Mobile homes,550.10 514.3(BI(1I GuarJmg live parts 600 volts or conduit,355.100) Planning, 90.8 Motors,430.14(A),430.16 lens. 110.27(C) Rigid metal conduit,344.1{}(D) Temporary,see Temporary in- Transformers,450.9,450.45 Induction and dielectric heating, Rigid polyvinyl chloride con- stallations Vessels,see also Fixed electric 665.23 duil,352.10(D) Theaters,520.5 heating equipment for Locked room or enclosure with Underground locations as, Types and materials.Chap.3 pipelines and vessels live pans over 600 300.5(B) Within sight From,.see In sight Definition,427.2 volts, 110.34(C), Wet procedure locations from Viewing tables,motion picture, 49U.2I(B)(7)Ex.. Health care facilities,517.20 Working space 530-1V 490.2 1(C It 2),490.211 E), Definition,517.2 About electrical equipment. Volatile flammable liquid 490.44(B 1,490.53. Windows,show,see Show 110.26, 110.32 through Definition.Art. 100-1 490.55 windows 110.3.1, 110,72. 110.73 2008 Edition NATIONAL ELECTRICAL CODE 74-821 Working space INDEX Adjacent to live parts(circuits _g_ _Z„ over 000 volts), 1103 2 X-ray equipment,517—V,Art.660 'Lone 0, 1,and 2 locations,seta to 110.34 Control,517.74,660-11 Hazardous(classified) Manholes, 110,72, 110.73 Definilions.517.2,660.2 locations,Class 1,Zone Motion picture projectors, Guarding and grounding, 0, 1,and 2 locations 540.12 517.78,660—IV Zone 20,21,and 22,see Hazard- Switchboards, 110.26,408.18 Transformers and capacitors, ous(classified) Workmanlike installation, 1 10.12. 517.76,660111 locations,Zone 20, 21, 640.6(A),720.11, 725.24,760.24.800.24, and 22 820.24,830.24 70-822 NATIONAL ELECTRICAL CODE 2008 Edition Tentative Interim Amendment NFPA 7a® National Electrical Code@ 2008 Edition Reference: 645.17 TU 08-1 (SC 08-7 36/TIA Log#925) Pursuant to Section 5 of the NFPA Regulations Governing Committee Projects, the National Fire Protection Association has issued the following Tentative Interim Amendment to NFPA 709 National Electrical Codex, 2008 edition.The TIA was processed by the Technical Committee on CMP-12,and was issued by the Standards Council on July 24, 2008,with an effective date of August 13, 2008. A Tentative Interim Amendment is tentative because it has not been processed through the entire standards-making procedures. It is interim because it is effective only between editions of the stan- dard.A TIA automatically becomes a proposal of the proponent for the next edition of the standard; as such,it then is subject to all of the procedures of the standards-making process. 1. In NEC Article 645, revise 645.17 as follows: 645.17 Power Distribution Units. Power distribution units that are used for information technology equipment shall be permitted to have multiple pandboards within a single cabinet, provided that- the power distribution unit is utiliza- tion equipment listed for information technology application. The final text would read: 645.17 Power Distribution Units. Power distribution units that are used for information technology equipment shall be permitted to have multiple panelboards within a single cabinet, provided that the power distribution unit is utilization equipment listed for information technology application. Copyright D 2008 All RighLS Reserved NATIONAL FIRE PROTECTION ASSOCJATION Sequence of Events Leading to Issuance Committee Membership Classifications of an NFPA Committee Document The following classifications apply to Technical Commit- tee members and represent their principal interest in the activity of the committee. Step 1: Call for Proposals M Manufacturer:A representative of a maker or mar- •Proposed new Document or new edition of an existing keter of a product, assembly. or system, or portion Document is entered into one of two yearly revision cy- thereof, that is affected by the standard. cles, and a Call for Proposals is published. U User:A representative of an entity that is subject to Step 2: Report on Proposals (ROP) the provisions of the standard or that voluntarily uses the standard. *Committee meets to act on Proposals, to develop its own I/M InstallerliWaintainer:•A representative of an entity that is in the business of installing or maintaining Proposals,and to prepare its Report. •Committee votes by written ballot on Proposals. If two- a product,assembly, or system affected by the stan- lard. thirds approve, Report goes forward. Lacking two-thirds L Labor labor representative or employee con- cerned with safety in the workplace. •Report on Proposals (ROP) is published for public re R/T l ppliarl Rvserrrrla/7PStctrg Laboratory:A representative view and comment. of an independent testing laboratory or indepen- Step 3• Report on Comments (ROC) dent applied research organization that promul- gates and/or enforces standards. •Committee meets to act on Public Comments to develop E Enforcing Authority:A representative of an agency its own Comments, and to prepare its report. or an organization that promulgates and/or en- •Committee votes by written ballot on Comments. If two- forces standards, thirds approve, Report goes forward. Lacking two-thirds I Insurance:A representative of an insurance com- approval, Report returns to Committee. pany, broker, agent, bureau, or inspection agency. •Report on Comments (ROC) is published for public re- C Consumer:A person who is, or represents, the ul- view, timate purchaser of a product, system, or service affected by the standard, but who is not included Step 4: Technical Report Session in the Ber class if icati on. SE Special Expert:A person not representing any of •"Notices of intent to make a motion"are filed, are reviewed, the previous classifications, but who has a special and valid motions are certified for presentation at the expertise in the scope of the standard or portion Technical Report Session. ("Consent Documents" that thereof have no certified motions bypass the Technical Report Session and proceed to the Standards Council for issu- NOTES; ance.) 1. "Standard" connotes code, standard, recommended •NFPA membership meets each June at the.annual Meet- practice, or guide. ing Technical Report Session and acts on Technical 2 A representative includes an employee. Committee Reports (ROP and ROC) for Documents While these classifications will be used by the Standards with "certified amending motions." Council to achieve a balance for Technical Committees, . Committee(s) vote on any amendments to Report ap- the Standards Council may determine that new classifi- proved at NFPA Annual Membership Meeting, cations of members or unique interests need representa- Step 5• Standards Council Issuance tion in order to foster the best possible committee delib- erations on any project. In this connection, the Standards *Notification of intent to file an appeal to the Standards Council may make appointments as it deems appropriate Council on Association action must be filed within 20 in the public interest, such as the classification of"Utili- days of the NFPA Annual Membership Meeting. ties" in the National Electrical Code Committee. "Standards Council decides, based on all evidence, 4. Representatives of subsidiaries of any group are gener- whether or not to issue Document or to take other ac- ally considered to have the same classification as the par- tion,including hearing any appeals. ent organization. NEC SCHEDULE FOR 2011 (2010 World Safety Conference and Exposition®) No.of Weeks Between each Date Event Event Nov. 7,2008 - Receipt of Proposals Jan. 11-24, 2009 10(+1) Code-Making Panel Meetings(ROP) Jan. 30,2009 1 Mail Ballots to CMPs Feb. 27,2009 4 Receipt of Ballots April 27-May 1, 2009 8 Correlating Committee Meeting June 1-4,2009 -- NFPA Annual Meeting—TBD June 19,2009 7 NEC-ROP to Printer July 14, 2009 4 NEC-ROP to Mailing House Oct. 23,2009 14 Closing Date for Comments Dec. 1-Dec. 14,2009 5 Code-Making Panel Meetings(ROC) Dec. 18,2009 1 Mail Ballots to CMPs Jan. 12,2010 3 Receipt of Ballots Feb.22-26,2010 5 Correlating Committee Meeting March 5,2010 1 NEC-ROC to Printer March 28,2010 3 NEC-ROC to Mailing House May 7,2010 6 Intent to Make Motion(ITMAM) May 21, 2010 2 Posting of ITMAMs June 6-10, 2010 2 NFPA Annual Meeting--TBD July 2010 Standards Council Issuance Sept. 2010 Release of 2011 NEC Rev 6/13106 Anyone may submit proposals to amend the 2008 Code.A sample form for this purpose may be obtained from the Secretary of the Standards Council at NFPA headquarters, and a copy is included in this Code. Method of Submitting a Proposal to Revise the National Electrical Code The following is based on the NFPA Regulations Governing Committee Projects, adopted by the Board of Directors in October 1996(last amended in March 2004). A proposal to revise the 2008 edition of the National Electrical Code must be submitted so that the proposal is received at NFPA headquarters by November 7, 2008,as indicated in the time schedule for the 2011 National Electrical Code.A proposal received after this date will be returned to the submitter.The proposal is to be sent to the Secretary of the Standards Council at NFPA Headquarters, 1 Batterymarch Park,P.O.Box 9101,Quincy,MA 02169- 7471. Each proposal must include the following: 1. Identification of the submitter(the person's name)and his or her affiliation(i.e.,committee,organization, company),where appropriate 2. An indication that the proposal is for revision of the 2008 National Electrical Code and identification of the specific section number,table number(or equivalent identification)of the section,etc.,to be revised 3. A statement of the problem and substantiation for the proposal 4. The proposed text of the proposal including the wording to be added,revised(and how revised),or deleted Proposals that do not include all of the above information may not be acted on by the National Electrical Code Committee. It is preferred that the forms available from NFPA for submittal of proposals be used.A separate proposal form should be used for revision of each section of the Code. Proposal forms appear on the following pages. FORM FOR PROPOSALS FOR 2011 NATIONAL ELECTRICAL CODE® INSTRUCTIONS—PLEASE READ CAREFULLY FOR OFFICE USE ONLY Type or print legibly in black ink. Use a separate copy for each proposal. Limit Log#: each proposal to a SINGLE section.All proposals must be received by NFPA by 5 p.m.,EST,Friday,November 7,2008,to be considered for the 2011 National Rate Rec'd: Electrical Code. Proposals received after 5:00 p.m„EST,Friday,November 7,2008, will be returned to the submitter. If supplementary material (photographs, diagrams,reports, etc.) is included,you may be required to submit sufficient copies for all members and alternates of the technical committee. Please indicate in which formal you wish to receive your ROP/ROC ❑electronic ❑paper ®download (Note: If choosing the download option,you must view the ROP/ROC from our website:no copy will be sent to you.) Date 8/1/20OX Name John B.Smith Tel.No. 253-555-1234 "ompany ABC Electric Company street Address 9 Seattle St. City Tacoma State WA Zip 98402 Please indicate organization represented(if any) National Electrical Contractors Association 1. Section/Paragraph 210-60(A) 2. Proposal Recommends(check one): ❑new text ®revised text ❑ deleted text 3. Proposal(include proposed new or revised wording,or identification of wording to be deleted): [Note: Proposed text should be in legislative format;i.e.,use underscore to denote wording to be inserted(inserted wording)and strike-through to denote wording to be deleted (deleted wording).] Guest rooms or guest suites fnee6ng the definitien ' provided with permanent provisions for cooking shall have receptacle outlets installed in accordance with all of the applicable rules in 210.52. 4. Statement of Problem and Substantiation for Proposal:(Note: State the problem that would be resolved by your recommendation;give the specific reason for your Proposal,including copies of tests,research papers,lire experience,etc.If more than 200 words,it may be abstracted for publication.) The existing language is modified to eliminate confusion between the electrical and building codes as to the precise definition of these types of accommodations. 5. Copyright Assignment (a) ®I am the author of the text or other material(such as illustrations,graphs)proposed in this Proposal. (b) ❑Some or all of the text or other material proposed in this Proposal was not authored by me. Its source is as follows (please identify which material and provide complete information on its source): I agree that a»r material that I author, either indisiduullr or with others, in connection with hark performed hP an NFPA Technical Committee shall he considered to be xvtrks made fir hire fur the.%FPA_ To the extent that 1 recant anY rights in copyright as to such material,or as to ant,other material aruhored hr me Thal I suhmu far the rise qJ an NFPA Technical Committee in the drgf ing of au,VFPA code, standard, or other NFPA docrmrent, 1 herehr grant and assign all and fill ell rights in copyright to the NFPA. I feerrher ggree and acknowledge that I acquire no rights in am publication of the NFPA and that copyright and all rights in materials produced hr.VFI'A Technical Comminees are osyned hr the NCPA and that the NFPA men•register copyright in irs own name. Signature(Required) PLEASE USE SEPARATE FORM FOR EACH PROPOSAL•NFPA Fax: (617)770-3500 Mail to: Secretary,Standards Council,National Fire Protection Association, 1 Batterymarch Park,Quincy,MA 02169-7471 7/17/2007 FORM FOR PROPOSALS FOR 2011 NATIONAL ELECTRICAL CODE® INSTRUCTIONS—PLEASE READ CAREFULLY FOR OFFICE USE ONLY Type or print legibly in black ink. Use a separate copy for each proposal. Limit Log#: each proposal to a SINGLE section. All proposals must be received by NFPA by 5 p.m.,EST,Friday,November 7,2008,to be considered for the 201 I National Date Rec'd: Electrical Code. Proposals received after 5:00 p.m., EST,Friday,November 7,2008, will be returned to the submitter. If supplementary material(photographs,diagrams,reports, etc.)is included,you may be required to submit sufficient copies for all members and alternates of the technical committee. Please indicate in which format you wish to receive your ROP/ROC ❑electronic ❑paper ❑download (Note: If choosing the download option,you must view the ROP/ROC from our website;no copy will be sent to you.) Date Name Tel.No. Company Street Address City State Zip Please indicate organization represented(if any) 1. Section/Paragraph 2. Proposal Recommends(check one): ❑new text ❑revised text ❑deleted text 3. Proposal(include proposed new or revised wording,or identification of wording to be deleted): [Note: Proposed text should be in legislative format;i.e.,use underscore to denote wording to be inserted(inserted wording)and strike-through to denote wording to be deleted (deleted-►veFdifl )•l 4. Statement of Problem and Substantiation for Proposal:(Note:State the problem that would be resolved by your recommendation;give the specific reason for your Proposal,including copies of tests,research papers,fire experience,etc. If more than 200 words,it may be abstracted for publication.) 5. Copyright Assignment (a) ❑ 1 am the author of the text or other material(such as illustrations,graphs)proposed in this Proposal. (b) ❑Some or all of the text or other material proposed in this Proposal was not authored by me. Its source is as follows (please identify which material and provide complete information on its source): I agree that any material that I author, either individually or with others, in connection with work performed by an NFPA Technical Committee shall he considered to he i orks made for hire for the NFPA. To the extent that 1 retain any rights in copyright as to such material,or as to any other material authored by me that 1 submit far the use of an NFPA Technical Committee in the drafting of an NFPA code, standard, or other NFPA document, I hereby grant and assign all and full rights in copyright to the NFPA. 1 fitrther agree and acknowledge that I acquire no rights in any puhlicatton of the NFPA and that copyright and all rights in materials produced by NFPA Technical Committees are ou-ned by the NFPA and that the NFPA may register copyright in its own name. Signature(Required) PLEASE USE SEPARATE FORM FOR EACH PROPOSAL•NFPA Fax: (6I7)770-3500 Mail to: Secretary,Standards Council,National Fire Protection Association, 1 Batterymarch Park,Quincy,MA 02169-7471 711 712 00 7 FORM FOR PROPOSALS FOR 2011 NATIONAL ELECTRICAL CODE® INSTRUCTIONS—PLEASE READ CAREFULLY FOR OFFICE USE ONLY Type of print legibly in black ink. Use a separate copy for each proposal. Limit frog#: each proposal to a SINGLE section.All proposals must be received by NFPA by 5 p.m.,EST,Friday,November 7,2008,to be considered for the 2011 National Date Rec'd: Electrical Code. Proposals received after 5:00 p.m., EST, Friday,November 7,2008, will be returned to the submitter. If supplementary material (photographs,diagrams,reports, etc.) is included,you may be required to submit sufficient copies for all members and alternates of the technical committee. Please indicate in which format you wish to receive your ROP/ROC ❑electronic ❑paper ❑download (Note: Ir choosing the download option,you must view the ROP/ROC from our website;no copy will be sent to you.) Date Name Tel.No. Company Street Address City State Zip Please indicate organization represented(if any) 1. Section/Paragraph 2. Proposal Recommends(check one): ❑new text ❑revised text ❑deleted text 3. Proposal(include proposed new or revised wording,or identification of wording to be deleted): [Note:Proposed text should be in legislative format;i.e.,use underscore to denote wording to be inserted(inserted warding)and strike-through to denote wording to be deleted (deleted werdiFi )] 4. Statement or Problem and Substantiation for Proposal:(Note:State the problem that would be resolved by your recommendation;give the specific reason for your Proposal, including copies of tests.research papers,fire experience,etc.If more than 200 words,it may be abstracted for publication.) 5. Copyright Assignment (a) ❑ I am the author of the text or other material(such as illustrations,graphs)proposed in this Proposal. (b) ❑Some or all of the text or other material proposed in this Proposal was not authored by me. Its source is as follows (please identify which material and provide complete information on its source): I agree that any material that I author. either individually or with others, in connection with work performed by an NFPA Technical Committee shall be considered 10 be works made for hire for the NFPA. To the extent that I retain any rights to copyright as to such material,or as to any other material authored by me that I submit for the use of an NFPA Technical Committee in the drafting of an NFPA code. standard. or other NFPA document, 1 hereby grant and assign all and full rights in copyright to the NFPA. 1 further agree and acknowledge that I acquire no rights in any publication of the NFPA and that copyright and all rights in materials produced by NFPA Technical Committees are owned by the NFPA and that the NFPA may register copyright in its own name. Signature(Required) PLEASE USE SEPARATE FORM FOR EACH PROPOSAL•NFPA Fax: (617)770-3500 Mail to: Secretary,Standards Council,National Fire Protection Association, I Batterymarch Park,Quincy,MA 02169-7471 7/17/2007 FORM FOR PROPOSALS FOR 2011 NATIONAL ELECTRICAL CODES INSTRUCTIONS—PLEASE READ CAREFULLY FOR OFFICE USE ONLY Type or print legibly in black ink. Use a separate copy for each proposal. Limit Log#: each proposal to a SINGLE section.All proposals must be received by NFPA by 5 p.m., EST,Friday,November 7,2008,to be considered for the 2011 National Date Rec'd: Electrical Code. Proposals received after 5:00 p.m., EST,Friday,November 7,2008, will be returned to the submitter. If supplementary material (photographs,diagrams,reports, etc.)is included,you may be required to submit sufficient copies for all members and alternates of the technical committee. Please indicate in which format you wish to receive your ROP/ROC ❑electronic ❑paper ❑download (Note: If choosing the download option,you must view the ROPIROC from our websi(e;no copy will be sent to you.) Date Name Tel,No. ,ompany Street Address City State Zip Please indicate organization represented(if any) 1. Section/Paragraph 2. Proposal Recommends(check one): ❑new text ❑revised text ❑deleted text 3. Proposal(include proposed new or revised wording,or identification of wording to be deleted): [Note:Proposed text should be in legislative format;i.e.,use underscore to denote wording to be inserted(inserted wordint!)and strike-through to denote wording to be deleted deleted aia 4. Statement of Problem and Substantiation for Proposal:(Note: State the problem that would be resolved by your recommendation;give the specific reason for your Proposal,including copies of tests,research papers,fire experience,etc. If more than 200 words,it may be abstracted for publication.) 5. Copyright Assignment (a) ❑ I am the author of the text or other material(such as illustrations,graphs)proposed in this Proposal. (b) ❑Some or all of the text or other material proposed in this Proposal was not authored by me. Its source is as follows (please identify which material and provide complete information on its source): I agree that an material that I author,either individually or with others.in connection with work perforated by air NFPA Technical Committee shall be considered to be works made for hire for the NFPA. To the extent that 1 retain any rights in copyright ax to such material,or as to any other material authored by me that I submit for the use of an NFPA Technical Committee in the drafting of an NFPA code, standard, or other NFPA document. I hereby grant acrd assign all and full rights in copyright to the NFPA. I further agree and acknowledge that 1 acquire no rights in anY publication of the NFPA and shirt copyright and all rights in materials produced by NFP,4 Technical Committees are owned by the NFPA and that the NFPA may register copyright in its own name. Signature(Required) PLEASE USE SEPARATE FORM FOR EACH PROPOSAL+NFPA Fax: (617)774-3540 Mail to: Secretary,Standards Council,National Fire Protection Association, I Batterymarch Park,Quincy,MA 02169-7471 V 17f2007 DAT STAY Up To= E0 � NFPA ToDAYI. 9YES please enroll me as a member of NFPA for the term checked below. Activate al I benefits, and ship my Member Kit including the Benefits Guide, Member Directory, and other resources to help me make the most of my NFPA membership. Please allow three to four weeks for the kit to arrive. BILLING INFORMATION: NI—me Title ,dnization Address City State Zip/Postai Code Country Phone E-mail Priority Code:8JW15-1Z PLEASE ANSWER THE FOLLOWING QUESTIONS: Job Title (check one) ❑ 1 year($150) 'krchitect, Engineer, Consultant, Contractor (C17) ❑2 years ($270) SAVE 430 tcilities Safety Officer(1`14) ❑3 years ($390)SAVE 40 ❑ Fire Chief, Other Fire Service (All) Annual r sl.pduesincludea$45wbxnplgntokfA4loumal®Regular mempershpoNFPA,nomdualand ❑ Loss Control, Risk Manager (L11) iron-traMferable NFPA journalIsareg+5teredt rademarkol the NaWal Fire fttectionAssmialion,Quincy,MA02169 Voting privileges begin after 180 days of indrodwal membersh p Prices when to change ❑ Inspector, Building Official, Fire Marshal (F03) ❑ Owner, President, Manager, Administrator (C10) PAYMENT MET�t0l): ❑ Other(please specify): (G11) Check One: Type of Organization (check one) ❑ Payment Enclosed (Make check payable toNFA4.) ❑ Architecture, Engineering, Contracting (A14) ❑ Purchase Order(Pteaseattach this form toyourPO.) ❑ Commercial Firm (Office, Retail, Lodging, Restaurant) (G13) ❑ BIII Me Later(Not avarrableon International membershps.) ❑ Electrical Services, Installation (J11) Charge My: ❑VISA ❑ MasterCard ❑AmEx ❑ Discover -ire Service, Public and Private(AA1) government(C12) Card # ❑ Industrial Firm (Factory, Warehouse) (C11) ❑ Institutional (Health Care, Education, Detention, Museums) (B11) Expiration Date ❑ Insurance, Risk Management (1312) ❑ Utilities (G12) Name on Card ❑ Other (please specify): (G11) Signature international members Please note prepayment 6 requaed or all IntMnatrOnal orders Be Sure 10 encktse a check or 4 EAsy'Mys TO JOIN WWI your preferred ciedrl card oPtar Fax: 1-800-593-6372, Outside the U.S.+1-508-895-8301 'I: NFPA Membership Services Center, 100% MONEY-BACK GUARANTEE 11 Tracy Drive, Avon, MA 02322-9908 online: nfpa.org If anytime during your first year you decide Call: 1-800-344-3555 membership is not for you, let us know and you`ll Outside the U.S. call +1-617-770-3000 receive a X00% refund of your dues. �, "MembermOnly" 'Benefits NFPA Keeps You Up-To-Date! 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