This is the second installment in a series of articles that will summarize about 220 significant changes in the 2002 NEC. These articles are intended to give the reader an overview of the types of changes that have been made during the last three-year Code development cycle. The panels considered more than 4,000 proposals and more than 2,000 public comments for the 2002 Code. The proposals, comments and panel statements provide the rationale behind the changes. These articles will not cover every change, and they are not intended to provide a full explanation of the reasons for the changes, as that information is available at www.necdirect.org, and will also be available in continuing education courses, books and videos on the changes.
Chapter 3 — Wiring Methods and Materials
Many of the Articles in Chapter 3 have been rewritten and relocated. A few articles that covered more than one wiring method have been separated into individual articles, one for each wiring method. Many of the raceway types have been given acronym type names. For example, Rigid Metal Conduit is now abbreviated “RMC.” The articles have also been rewritten for usability and arranged in a parallel manner so that similar subject matter is covered in the same section of each article. For example, Sections 330.30, 332.30, 342.30 and 334.30 are all about securing and supporting. These articles in Chapter 3 have been relocated:
Cable Articles
320 — Type AC — Old 333
322 — Type FC — Old 328
324 — Type FCC — Old 363
326 — Type IGS — Old 325
328 — Type MV — Old 326
330 — Type MC — Old 334
332 — Type MI — Old 330
334 — Type NM — Old 336
336 — Type TC — Old 340
338 — Type SE — Old 338
340 — Type UF — Old 339
Raceway Articles
342 — IMC — Old 345
344 — RMC — Old 346
348 — FMC — Old 350
350 — LFMC — Old 351 (A)
352 — RNC — Old 347
354 — NUCC — Old 343
356 — LFNC — Old 351 (B)
358 — EMT — Old 348
360 — FMT — Old 349
362 — ENT — Old 331
Others Including Some Raceways:
366 — Auxiliary Gutters — Old 374
368 — Busways — Old 364
370 — Cablebus — Old 365
372 — Cellular Concrete Floor Raceways — Old 358
374 — Cellular Metal Floor Raceways — Old 356
376 — Metal Wireways — Old 362(A)
378 — Nonmetallic Wireways — Old 62 (B)
380 — Multioutlet Assembly — Old 353
382 — Nonmetallic Extensions Old 342
384 — Strut-Type Channel Race-way — Old 352 (C)
386 — Surface Metal Raceways — Old 352 (A)
388 — Surface Nonmetallic Race-ways — Old 352 (B)
390 — Underfloor Raceways — Old 354
Article 300 — Wiring Methods
Section 300.1(C) — Table 300.1(C) was added to provide a list of trade sizes and equivalent metric designators. A fine-print note explains that both metric designators and trade sizes are for identification only and do not represent actual dimensions. The metric designators are a permitted use of soft conversion from trade sizes according to Section 90.9.
Section 300.3(B)(3) — New language in this section refers to requirements for single conductor Type MC cables, which must have nonmagnetic cladding. This is intended to reduce the effects of induction where the individual circuit conductors are surrounded by a conductive layer and are not in the same cable.
Section 300.4(B)(1) — The grommets or bushings required for NM cable in metal studs must be listed.
Section 300.4(D) — The exception for mobile homes and recreational vehicles has been removed. Since spacing and protection requirements for wiring run parallel to framing members now apply, protective sleeves or plates are now required in mobile homes and recreational vehicles where the minimum clearance is not maintained.
Section 300.5(D)(3) — The requirement for a warning ribbon above a service lateral has been expanded to cover other service conductors that are not encased in concrete.
Section 300.5(K) — Cables and raceways installed using directional boring equipment must be approved for the purpose. The concern is that cables and raceways may “necked-down” or otherwise damaged during installation. Listing for the purpose is not required. Approval is at the discretion of the Authority Having Jurisdiction (AHJ).
Section 300.6(A) — Field-threaded conduit must have the threads recoated using an approved, electrically conductive, corrosion-resistant compound.
This recoating is required only where corrosion protection is necessary, such as in underground installations or in other corrosive environments.
Section 300.7(A) — Sleeves passing between areas of different temperatures must be sealed where condensation “is known to be a problem.” The substantiation for this change was to reduce energy loss as well as providing for equipment safety.
Section 300.11(C) — The prohibited use of raceways as a means of support for other systems or wiring is extended to cables. Cables are a little different however, because the exceptions that allow certain related Class 2 cables to be attached to a raceway do not apply to cables.
Section 300.15 — This section was rewritten to more clearly identify what types of equipment may be used without or in lieu of boxes. All subsections have been reworded into complete sentences that state explicitly what is permitted, required or not required.
Section 300.22(B) and (C) — Only wiring methods without an overall nonmetallic covering are allowed in environmental air spaces. The exception for limited lengths of liquidtight flexible metal conduit has been deleted.
Article 305 — Temporary Wiring
Article 305 has been relocated and renumbered as Article 527 in Chapter 5.
Article 312 — Cabinets, Cutout Boxes, and Meter Socket Enclosures
Article 373 in the 1996 NEC has been relocated and renumbered as Article 312. This is in keeping with the general organization of the Code and the chapter, which provides the most general rules near the beginning and more specific rules near the end.
Section 312.6 (B)(2) — Wire bending space requirements for compact stranded aluminum conductors have been reduced where the conductors enter an enclosure through a wall opposite the terminals. This change allows conductors of the same ampacity to have the same wire bending space, even though the equivalent aluminum conductors may be slightly larger in diameter.
Article 314 — Outlet, Device, Pull and Junction Boxes; Conduit Bodies; Fittings and Manholes
Article 314 has been relocated and renumbered from its old location in Article 370. The title was also revised to include manholes. A part covering manholes and other enclosures for personnel entry was added to this article in the 1999 Code.
Section 314.16(A)(2) — Required volume markings have been changed to generic markings from the previous requirement that required marking in cubic inches. Now boxes may be marked in cubic inches or cubic centimeters. The marking requirement applies only to boxes up to 100 cubic in. or 1650 cubic cm.
Section 314.22 — Surface extensions must be made with an extension box. A surface box mounted over a flush box is not permitted. Flexible extensions may still be made from a cover of a flush box if the cover is unlikely to fall off and grounding continuity does not depend on the cover-to-box connection.
Section 314.23 (B)(1) — This minor revision adds screws to the permitted fastening means for boxes. Previously, only nails were mentioned.
Section 314.27 (A) — Wall mounted fixtures that weigh 6 lbs or less can be supported with plaster rings or device boxes using No. 6 or larger screws. The 16 in. size limit was deleted.
Section 314.27 (B) — The rules for boxes used for support of luminaires were moved from Article 410 to this section.
Section 314.54 — Criteria for the arrangement of conductors in manholes has been added. Conductors must be cabled, racked or otherwise arranged to provide safe access for personnel entry.
Article 320 — Armored Cable: Type AC
Section 320.30 (B)(3) — Type AC cable may be extended more than 6 ft from an outlet to a luminaire if supported within 6 ft of the luminaire.
Article 330 — Metal-Clad Cable: Type MC
Section 330.30 (B)(2) — Type MC cable may be extended more than 6 ft from an outlet to a luminaire if supported within 6 ft of the luminaire.
Section 330.80 — Methods of determining ampacities for single conductor Type MC cables grouped together have been added.
Section 330.116 — Single conductor Type MC cable is permitted but must have a nonmagnetic sheath or armor.
Article 332 — Mineral-insulated, Metal-Sheathed Cable: Type MI
Section 332.80 — Ampacity determination for Type Mineral Insulated, Metal-Sheathed cable is now covered in Article 332. The temperature rating of the end seal fittings becomes a limiting factor in the selection of an ampacity.
Article 334 — Nonmetallic-Sheathed Cable: Types NM, NMC and NMS
Section 334.6 — Cable Types NM, NMC and NMS must be listed.
Section 334.10 — Type NM cable is now permitted to be used in any occupancy type that is combustible construction. Annex E includes definitions of construction types. The long-standing but controversial three-story height limitation has been eliminated. The use of the cable is still subject to specific occupancy restrictions in Chapter 5.
Section 334.17 — The listed grommets required in metal studs by Section 300.4(B)(1) are required to remain in place.
Section 334.30(B)(2) — Type NM cable may be extended more than 4-½ ft from an outlet to a luminaire if supported within 4-½ ft of the luminaire.
Article 338 — Service-Entrance Cable: Types SE and USE
(Article 338 is one of the only Articles in Chapter 3 that did not get renumbered.)
Section 338.10 (B) — Uninsulated conductors in Type SE cable may only be used for equipment grounding when the cable is used for branch circuits or feeders.
Section 342.24 — The minimum radius of bends has been revised to measure to the centerline of the conduit rather than to the inner edge of the bend. Dimensions are given in Table 344.24. This change allows for slightly tighter bends.
Section 342.30(B)(3) — The support spacing for exposed vertical risers has been extended to 20 ft for fixed equipment. The previous rule allowed this greater support spacing only for industrial machinery.
Article 344 Rigid Metal Conduit — Type RMC
Section 344.24 — The minimum radius of bends has been revised to measure to the centerline of the conduit rather than to the inner edge. Dimensions are given in revised Table 344.24, which combines the dimensions for one-shot and other field bends in one table. The new rule allows for slightly tighter bends. Table 344.24 applies to most other raceways that can be field bent because the other raceway articles refer to Table 344.24 for bending dimensions.
Section 344.30(B)(3) — Support spacings for exposed vertical risers has been extended to 20 ft for fixed equipment in addition to industrial machinery.
Article 362 — Electrical Nonmetallic Tubing: Type ENT
Section 362.10(2) and (5) — This section now allows ENT above three floors and above suspended ceilings without a thermal barrier in fully sprinkled buildings.
Article 392 — Cable Trays
Section 392.10 (B) — This section added 50 mm (2 in.) size for ventilated channel cable trays used with single-conductor cables. A proposal to recognize an 8 in. size was rejected. The 2 in. size is not recognized for multiconductor cables.
Article 400 — Flexible Cords and Cables
Section 400.8(5) — Flexible cord may not be located above suspended or dropped ceilings. Such spaces may be considered to be “exposed” as defined in Article 100, and previous wording only prohibited concealed installations.
Article 404 — Switches
Article 404 was relocated from Chapter 3. The previous number was Article 380. Chapter 4, Equipment for General Use, is a more logical location for Switches than Chapter 3, Wiring Methods.
Section 404.6 (C) — Bolted pressure contact switches must have barriers that guard energized blades. The blades in some such switches do remain energized in the open position.
Section 404.14 (E) — Dimmers are restricted to use with permanently controlled incandescent luminaires unless specifically listed otherwise. This is intended to restrict the use of general purpose dimmers on receptacles used as lighting outlets.
Section 404.15 (B) — Occupancy switches and similar devices with a marked “off” position must disconnect all ungrounded conductors when the switch is in the “off” position.
Some occupancy switches have relied on a backfeed or a small leakage current through the load to maintain power to the device.
Article 406 — Receptacles, Cord Connectors and Attachment Plugs (Caps)
This new article was part of Article 410 in the previous Code.
Section 406.3(D) — Requirements for replacement receptacles have been logically relocated from Article 210 as such rules were about the receptacles, not about the branch circuits.
Section 406.8 (B)(1) — This section has been revised to clarify requirements for receptacle covers in wet locations. All 15A and 20A, 125V receptacles installed outdoors in wet locations must now have covers that remain weatherproof with or without a plug inserted.
Other receptacles in wet locations must also be weatherproof with or without the plug inserted if the equipment is likely to be left unattended while in use. Such receptacles can be weatherproof only with the plug removed if the equipment will be attended while in use.
Article 408 — Switchboards and Panelboards
This article was relocated from Chapter 3. It was Article 384 in the 1999 NEC.
Article 410 — Luminaires (Lighting Fixtures), Lampholders and Lamps
Section 410.18 (B) — Alternative methods of grounding like those permitted for replacement of ungrounded receptacles are now also permitted for replacement luminares.
Section 410.31 — Section 410.31 has been rewritten and replaced by Sections 410.31, 410.32 and 410.33. Section 410.31 covers luminaires used as raceways. Section 410.32 covers luminaires connected together end-to-end or by recognized wiring methods. It permits certain circuits to be run through such fixtures. 410.33 covers the branch circuit conductors that may be run within 3 in. of a ballast.
Section 410.32 — Luminaires are not required to be listed as raceways where they are connected together end-to-end or connected together by recognized wiring methods.
Section 410.80(A) — Electric discharge lighting over 1,000V must be listed and installed according to the listing.
Article 430 — Motors, Motor Circuits and Controllers
Section 430.32 (C)(Formerly 430-34) — More than one size adjustment is allowed for overload protection of motors where necessary to get the motor started and running, but the 140% limit (130% in some cases) still applies.
Section 430.52 — Table 430.52 has been relocated to Section 430.52. The table has been modified to group Design E and Energy-Efficient Design B motors together under the same sizing rules.
Sections 430.62(A) and 430.63 — New (mandatory) exceptions require motor feeder overcurrent protective devices to comply with 430.94 if they are also used to provide overcurrent protection of an MCC. MCCs must be protected at the rating of the common power bus.
Section 430.102 — Local disconnects will be required at (in sight of) motors unless the disconnect for the controller is also in sight of the motor. Lockable disconnects at controllers no longer provide a blanket exception. New exceptions apply for industrial facilities with written safety (lock-out/tag-out) programs or where a greater hazard is created. A fine- print note provides examples of greater hazards.
Article 440 — Air-Conditioning and Refrigerating Equipment
Section 440.14 — A/C disconnects may not be mounted on panels intended for access to the A/C equipment.
Section 440.32 — Additional language covers conductor sizing for wye-start, delta-run compressor motors. The sizing requirements here are the same as in 430.22(C).
Section 440.62(C) — Cord- and plug-connected room air conditioners may exceed 50% of a branch circuit that also supplies other loads if the other loads are interlocked to prevent simultaneous operation of the air conditioner and the other loads. The load is still limited to 80% of the circuit rating.
Section 440.65 — Leakage Current Detection and Interruption (LCDI) or AFCI protection must be provided for cord-and-plug-connected room air conditioners. The protection is required to be in the attachment plug cap or within 12 in. of the plug cap. LCDI protection is defined in Section 440.2.
Article 490 — Equipment, Over 600V, Nominal
Section 490.21 — Specific wording for warning signs has been eliminated. Warning signs are still required under subsections (B)(7), (C)(2) and (E) but the wording is no longer specified.
Article 501 — Class I Locations
Section 501.4(B)(3) — This change modifies the rules for Nonincendive Field Wiring.
Article 504 — Intrinsically Safe Systems
Section 504.80(B) — The marking requirements for intrinsically safe wiring were revised to be certain that at least one marking will be visible in each separated area or room.
Article 505 — Class I, Zone 0, 1, and 2 Locations
Article 505 has been rewritten to be a more complete article so that referring back to Article 501 for installation requirements is not generally required.
Section 505.8(I) — Combustible gas detection is now recognized as a protection technique in Class I, Zone classified areas.
Section 505.9(A) — Equipment identification and approval requirements were revised and clarified. Listing is generally required for equipment in Zone-classified areas, but some equipment identified in other ways is also permitted.
Article 513 — Aircraft Hangars
Zone classification and protection techniques are recognized in aircraft hangars.
Article 514 — Motor Fuel Dispensing Facilities
This article has a new title. The title has been changed from “Gasoline Dispensing and Service Stations” to “Motor Fuel Dispensing Facility” to broaden the scope of the article and to cover other fuels, such as propane.
Article 515 — Bulk Storage Plants
Zone classification and protection techniques are recognized in bulk storage plants.
Article 517 — Health Care Facilities
Section 517.2 — The definition of “Health Care Facility” was modified to clearly include psychiatric facilities.
Section 517.18 — Tamper-resistant covers or receptacles are required for all types of receptacles in pediatric care areas. Previously only 15A and 20A 125V receptacles were covered by this requirement.
Section 517.30(E) — All receptacles supplied by the emergency system in a hospital must be identified, not just those on the critical branch.
Section 517.34 Exc. — The time-lag interval for delayed automatic connection of the equipment system is no longer required for small essential electrical systems, which permits the use of a single transfer switch in such cases.
The previous Code had a diagram of such an installation, but the literal Code language required delayed connections to equipment, and that requires more than one transfer switch.
Section 517.41(E) — Distinctive identification for emergency receptacles is now required in nursing homes and limited care facilities.
Section 517.43 Exc. — The time-lag interval for delayed automatic connection of the equipment system is no longer required for small essential electrical systems in nursing homes, which permits the use of a single transfer switch in such cases.
Article 520 — Theaters, Audience Areas of Motion Picture and Television Studios, Performance Areas and Similar Locations
The title of Article 520 was changed to include “Performance Areas.”
Section 520.1 — The scope of this article was revised to specifically include outdoor areas such as stadiums used for musical, dramatic or other performances.
Article 525 — Carnivals, Circuses, Fairs and Similar Events
Section 525.20(G) — The permitted uses of cords are revised and clarified. Cords must be arranged to minimize tripping hazards. Mats may be used if the tripping hazard is not increased. Cables are permitted to be buried temporarily and do not have to comply with the burial depths of 300.5.
Article 527 — Temporary Installations
Article 527 was previously Article 305. Temporary wiring rules modify the usual rules of Chapter 3 and so do not belong in Chapter 3. There was some discussion about whether temporary wiring is a “special occupancy” as implied by its location in Chapter 5 or a “special condition” covered by Chapter 7, but the decision was made to locate temporary installations in Chapter 5.
Section 527.3(B) — The 90-day time limit for temporary wiring applies to “holiday decorative lighting” rather than just “Christmas decorative lighting” so that temporary decoration for such holidays as Halloween is now covered.
Section 527.4(J) — Vegetation is not permitted as support for overhead spans of temporary branch circuits or feeders. This does not affect the use of lighting in trees and other vegetation, but branch circuits may not be strung overhead between trees or other vegetation.
Section 527.6(A) — An assured equipment grounding conductor program may be used in lieu of GFCI protection, but only in industrial occupancies where equipment is not GFCI-compatible or where a greater hazard would be introduced by a power interruption.
Article 547 — Agricultural Buildings
Section 547.5 (C) — The requirements for enclosures in agricultural buildings have been clarified.
Section 547.5 (G) — GFCI protection is now required on all 125V, 15A or 20A receptacles installed outdoors or in wet or damp locations in addition to the areas having an equipotential plane.
Section 547.9 — Requirements for power distribution at groups of agricultural buildings was clarified from the extensive revisions made in the 1999 NEC. The disconnect at a distribution point is now called a “site isolating device.” The device must provide for connecting a grounding electrode conductor to a grounded conductor, but is not required to include overcurrent protection or to be listed as service equipment. Utility-supplied disconnects may be used in some cases.
Equipment grounding conductors installed between the site isolating device and a building disconnect must be sized equivalent to the ungrounded conductors.
Section 547.10 — Requirements for equipotential planes have been clarified, especially for dirt confinement areas. GFCI protection may be used in lieu of equipotential planes where floors are dirt. Voltage gradient ramps are no longer required.
Article 550 — Mobile Homes, Manufactured Homes and Mobile Home Parks
Article 550 has been rewritten to correlate with NFPA 501 and HUD standards.
Section 550.15 — Aluminum wiring, including aluminum alloys and copper-clad aluminum, is no longer permitted in branch-circuit wiring in mobile homes and manufactured housing.
Section 550.25 — AFCI protection is required for bedroom branch circuits in mobile homes and manufactured housing. AFCI protection is not currently required by HUD standards or NFPA 501.
Article 555 — Marinas and Boatyards
Section 555.1 — The revised scope of this article excludes private, noncommercial docking facilities for single-family dwellings.
Section 555.2 — A definition of “Electrical Datum Plane” has been added. This is generally 2 ft above highest normal water level or high tide. For floating piers and landing stages it is 30 in. above water level and 12 in. above the deck. The datum plane establishes a minimum level for locating electrical connections and receptacles.
Section 555.19(A)(4) — The minimum rating of receptacles that provide shore power for boats is now 30A. Boat length is no longer a consideration in selecting receptacle ratings. 60A and 100A pin-and-sleeve receptacles have been added.