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This series of articles 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 NE Code 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 readily available on NFPA's Web page on the NEC,, and will also be available in continuing education courses, books and videos on the changes.

This summary will describe the changes in the order they appear in the new 2002 Code so the reader can, if they wish, concentrate on those areas in which they are most interested.


Some changes will appear throughout the new Code. Many changes have been made to improve the usability of the NEC for the traditional U.S. users as well as international users. One of the most obvious global changes that affects the entire book is the conversion from the familiar “dash” format to a “dot” format in section numbering. Thus Section 250-50 becomes 250.50.

Another global change concerns measurements, which will now be listed in SI (metric) units first, followed by English (foot/pound) measurements in parentheses. Generally, a hard conversion is preferred. In hard conversions, the “equivalent” measurements are actually approximations. For example, although 15m and 50 ft are not precisely the same distance, both offer easily applied round numbers that provide equivalent safety. Trade sizes have been assigned metric designators because the trade sizes are not actual dimensions. Conversions and the use of metric designators are covered in Section 90.9. A table of trade sizes and equivalent metric designators is located in Section 300.1(C).

The use of numbers to describe wire sizes has also been changed throughout the NEC. A “No. 10-in. wire is more accurately called a size “10 AWG” (American Wire Gauge) wire, so references to wire sizes have changed accordingly.

The organization of the NEC has been changed slightly to provide a more uniform arrangement of articles, parts, sections, subsections and lists. Article numbering has not changed, but parts are now identified by a Roman numeral rather than an upper case letter.

Section numbering has not changed either, although many articles have been rewritten or reorganized to have consistent numbering. Subsections are now numbered using upper case letters, with the next lower level being identified by numbers. All lists are now numbered.

Other editorial changes and changes for usability include adding headings to most subsections, changing Appendices to “Annexes,” and rewriting exceptions into complete sentences, especially where the main rule contains more than one discrete requirement.

The term “fixture” has been replaced throughout the Code with the more complete and technically accurate term “luminaire.” For the time being, the term luminaire will be followed by “fixture” in parentheses.


This new article provides a set of administrative rules for adopting entities. The article covers such things as permits, plan review, inspections and appeals. Article 80 does not apply unless specifically adopted by the enforcing agency.


Section 90.1(d). This new subsection says that the fundamental principals of the IEC are addressed by the NEC.

Section 90.3. This section was clarified by replacing the word “independent” with “not subject to the requirements of Chapters 1 through 7” to make it more clear that communications circuits are covered by the Code.

Section 90.4. Waiving of requirements by an AHJ because an alternative method is deemed to provide equivalent safety must be done by “special permission,” which must be in writing. The written record is needed to provide a “paper trail” when alternative installations are permitted.

Section 90.4 has also been changed to specifically include Signaling and Communications in the scope of the Code for enforcement purposes.

Section 90.9. This new section covers units of measurement as noted in the discussion of metrication above. It explains the difference between hard and soft conversions, states a preference for hard conversions, and lists the conditions under which soft (mathematically equal) conversions are permitted.


Authority Having Jurisdiction. A new definition and Fine Print Note have been added to define “AHJ.” The definition and note explain that the AHJ could be an individual, a public entity or a designated agent.

Ground-Fault Circuit Interrupter. The revised definition and Fine Print Note explain that the term Ground-Fault Circuit Interrupter as used in the NEC refers to Class A (4-6 ma trip level) devices only.

Live Parts. This definition has been revised to read “energized conductive components.”

Luminaire. This term includes lamps, ballasts, provisions for directing light, positioning and protecting lamps and connections to supply and is thus a broader and more inclusive term than “fixture.”

Qualified Person. The definition of a qualified person has been revised to require safety training. This will make the definition more compatible with OSHA and NFPA 70E requirements.

Structure. A new definition of structure has been added: “That which is built or constructed.”


Section 110. A new scope statement has been added to this article. This represents an example of the effort to provide a scope statement in every article for improved usability. However, in this case, nothing was changed from the previously implied but unstated scope.

Section 110.14 (C). This section has been clarified. It now states that Table 310.16 is to be used in selecting conductor ampacities to comply with termination provisions. Other tables may be used for ampacities of conductors based on specific conditions of use, but for termination provisions, Table 310.16 applies.

Section 110.16. A new rule requires field marking of arc-flash hazards. The marking does not require a calculation of the incident energy that is used to select personal protective equipment under NFPA 70E, but does advise workers of the possible need for personal protective equipment.

Section 110.22. The wording in this section has been clarified to require all disconnects to be marked to indicate their purpose (unless the purpose is evident). Previous wording only required marking where the disconnect itself was required.

Section 110.23. A new requirement says unused current transformers associated with potentially energized circuits must be shorted. This will prevent a hazardous voltage from building up on the transformer.

Section 110.26(C)(2). This section covers entrances to workspace for “large equipment.” Panic bars or equivalent hardware will be required on large equipment room doors, and the doors will be required to open in the direction of exit travel.

Section 110.26(F). The 6-ft dedicated space above panels cannot be encroached upon with non-electrical equipment. Foreign systems may be installed above the dedicated space if the electrical equipment is suitably protected, but the protection, typically leak protection, must also be located outside above the dedicated space. Suspended ceilings with removable panels are the only foreign systems permitted within 6 ft of the top of a switchboard, panelboard, distribution board or MCC.

Section 110.31. A new table of required minimum distances between live parts and fences has been added for over 600V installations.

Section 110.31(A). This new section provides fire resistance requirements for electrical vaults for equipment over 600V. The requirements are essentially the same as the requirements in Article 450 for transformer vaults.

Section 110.33. Revisions to this section require panic bars or equivalent hardware on doors leading from working spaces for equipment over 600V. The doors will also be required to open in the direction of exit travel.

Section 110.58. Motors and transformers over 600V located in tunnels must have a disconnect within sight.


Section 200.6 (A). With this revision, grounded conductors may now be either white or gray. The color “natural gray” has been removed. A Fine Print Note at the end of the section warns Code users that some people may have used gray for ungrounded conductors in the past.

Section 200.6(D). Gray and white may be used to distinguish between grounded conductors of different systems. White wire with a colored stripe is still permitted but not required.


Section 210.7(C). Simultaneous disconnection is required for multiple circuits (could be multiwire branch circuits) when supplying equipment on a single yoke. This rule essentially extends the residential requirement of Section 210.4(B) to all occupancies.

210.8(A)(5). A new Exception No. 3 says receptacles dedicated to fire and burglar alarm systems in unfinished basements are not required to be GFCI protected. GFCI protection on circuits supplying fire alarm systems is not permitted by NFPA 72, National Fire Alarm Code. Other GFCI-protected receptacles are still required in unfinished basement areas.

210.8(A) and (B). GFCI requirements for dwelling kitchens are extended to all occupancies. However, in dwelling units only receptacles serving countertop areas must be GFCI protected, in other occupancies, all 15A and 20A, 125V receptacles in kitchens are covered, not just those serving countertops.

210.12. AFCI requirements have been expanded to cover all 15A and 20A, 125V (nominal) outlets, not just bedroom receptacle outlets. The new requirement covers lighting outlets and outlets for such things as smoke detectors as well as receptacle outlets. The AFCI protection must be provided for the entire branch circuit.

210.19(B). This new subsection covers branch circuits over 600V. Generally, conductors are to be sized at 125% of the “designed potential load that will be operated simultaneously.” Special rules apply to supervised installations, but those rules require documented training and experience for qualified persons.

210.21(B)(3). A new exception permits the rating of receptacles for electric discharge lighting to be less than the branch circuit rating. The receptacle rating may be based instead on Section 410.30(C) (125% of luminaire full-load current).

210.50(A). The wording, “supported by a permanently installed cord pendant” has been changed to “supplied by a permanently connected cord pendant.” The revised language emphasizes the electrical connection rather than the mechanical support. Such cord pendants with connectors are considered to be receptacle outlets.

210.52(D). This section was clarified to require bathroom receptacles to be located on a wall “or partition” adjacent to the basin “or basin countertop.”

210.52(G). Receptacles are required in each separate unfinished area of a dwelling unit basement. Where two unfinished areas are created by finishing a portion of a basement, two GFCI-protected receptacles will be required, one for each unfinished space.

210.63. A receptacle for servicing of “HACR” equipment must be provided on the same level and within 25 ft of all such equipment regardless of location. Previously, this rule applied only to rooftops, attics and crawl spaces and excluded rooftops in one- and two-family dwellings. Although this rule is intended to harmonize with mechanical code requirements, mechanical codes usually require receptacles for all mechanical equipment, including ventilation equipment (the “V” in “HVAC”). The NEC requirement does not cover ventilation equipment.


215.2(B). This new subsection was added to cover feeders over 600V. Three rules are provided for determining minimum capacity. For transformers, the load is not less than the sum of the nameplate ratings of the transformers. For other feeders, the load is “125% of the designed potential load of the utilization equipment that will be operated simultaneously.” Another option covers situations where design and installation are under engineering supervision and servicing is by “qualified persons with documented training and experience in over 600V systems.”

215.5. Revisions to this section changed “connected load” to “computed load” for the basis of a feeder diagram when such diagrams are required by the AHJ.


220.3(B)(8). Only that portion of a multioutlet assembly that actually contains receptacles is to be counted in the linear footage used for load calculations.

220.12(B). Where multicircuit track is installed for track lighting in other than dwelling units or hotel or motel guest rooms, the feeder load is considered to be evenly divided between the circuits.

220.18. The demand factor table for household clothes dryers has been revised for the fifth and sixth dryer. Previously, the demand load for four dryers was the same as for five dryers if they were all the same rating.


Section 225.26. The exception that allowed vegetation to be used for support in temporary installations has been deleted. Article 305 (now Article 527) did not permit this anyway.

Section 225.31(B). Section 230.6 may be used to determine when conductors are considered outside a building.


230.10. This new section prohibits trees or other vegetation from being used for the support of service conductors.

Section 230.33. Service laterals may be spliced or tapped subject to the same requirements given in 230.46 for service entrance conductors.

Section 230.82(2) and (8). Meter disconnecting disconnect switches are now permitted on the line side of a service disconnect.

Section 230.212. This section has been revised to change the voltage threshold from 15,000V to 35,000V with regard to the requirement that service conductors be terminated in metal-enclosed switchgear or a vault where they enter a building.


Section 240.2. This section contains all the definitions applicable to Article 240. The previous sections 240-2, 240-3 and 240-4 were renumbered as Sections 240.3, 240.4 and 240.5 respectively to accommodate the definitions in this location. Generally, when an article has definitions of terms that are specific to the article, those definitions are now in Section .2 of the article.

Section 240.2. The definition of “Tap Conductors” has been revised by adding a comma after “other than a service conductor” to clarify that service conductors are not to be considered tap conductors.

Section 240.21 (B)(5) and (C)(4). These sections have been clarified to include the intent of 230-6 in defining “conductors considered outside a building.”

Section 240.21 (C)(3). Although this rule has always been limited to industrial occupancies in the text of the main rule, “Industrial” has been made the first word in the Section heading to try to reduce misunderstandings and misapplications of the rule.

Section 240.21 (C)(5) and (6). Subsection (5) remains unchanged in covering secondaries where the transformer primary conductors are tapped from a feeder, but subsection (6) has been added to clarify that the full 25-ft rule can be applied to the secondary when the transformer primary conductors are protected at their ampacity, that is, when the primary conductors are not tap conductors. This was the intent of the previous language, but a literal interpretation would have required at least a short length of smaller “tap conductor”primary circuit.

Section 240.24(B) Exception. 2. This section has been clarified. Ready access to branch circuit overcurrent devices is not required for occupants of hotel/motel guest rooms.

Section 240.33. The requirement for vertical mounting of overcurrent device enclosures has been relaxed where vertical mounting is impracticable.

Section 240.83 (D). Circuit breakers used as switches for fluorescent lighting circuits must have an “SWD” marking as before, but where used with HID (High Intensity Discharge) lighting, the circuit breaker must be marked “HID.” The “HID” marking may be used in lieu of an “SWD” marking on fluorescent lighting circuits.

Section 240.85 and FPN. “Slash-rated” circuit breakers such as those rated “120/240V” or “480Y/277V” may be applied only on solidly grounded systems where the voltage to ground does not exceed the lower of the two ratings.

Section 240.92 (C). The language in this section has been modified to include the intent of 230-6 in determining when conductors are considered outside a building.


Sections 250-2, 3 and 4. These sections have been renumbered and reordered to accommodate all Article 250 definitions in Section 250.2.

Section 250.4(B). A new subsection was added to explain the performance requirements for grounding, bonding and fault current paths in ungrounded systems.

Section 250.20. This section has been revised to clarify that systems not required to be grounded, but grounded by choice, must still comply with Article 250.

Section 250.21. References to health care and electrolytic cells have been deleted from the list of systems not required to be grounded because these systems are not permitted to be grounded under 250.22. Only those circuits required to be ungrounded by Articles 517 and 668 are covered by 250.22. Other circuits in Articles 517 and 668 may still be required or permitted to be grounded. A general reference to systems not specifically required to be grounded under 250.20 (B), such as three-wire delta systems, has been added to clarify that these systems are permitted to be grounded.

Section 250.22. The secondary circuits of low voltage lighting are not permitted to be grounded by Article 411, so that prohibition has been added here as well.

Section 250.24(B)(1). This new rule requires the size of a grounded conductor in a three-phase, three-wire “corner-grounded” delta service to be not smaller than the ungrounded conductors.

Section 250.26(4). This section now covers multiphase systems where one phase is grounded by requirement or by choice. Previously only those systems in which a phase was required to be grounded were covered.

Section 250.30 (A)(3). A new subsection allows a continuous grounding electrode conductor to be extended through a building for one or more separately derived systems. The common grounding electrode conductor must be bonded to building steel if such steel exists in the areas served by the separately derived system(s). Tap connections must be made by exothermic welding or irreversible compression connectors that are listed for the purpose. This change more efficiently accommodates the change in the 1999 NEC that limited the use of a water pipe as a grounding electrode for separately derived systems to the first 5 ft of the pipe entering the building.

Section 250.32 (B). The grounded conductor to a separate building is required to be no smaller than the larger of the sizes required by 220.22 or 250.122. Equipment grounding conductors to separate buildings, where used, are sized according to 250.122.

Section 250.32 (F). The grounding electrode conductor at a separate building is to be sized from 250.66 rather than 250.122.

Article 250 Part III. This part, which covers the grounding electrode conductor and system, has been reorganized. Sections 250.50, 250.52 and 250.53 were revised and rearranged to cover the system, the electrodes and the installation of the electrodes respectively.

Section 250.52(A)(1). The exception that permits some exposed interior water piping to be used as part of the electrode system or to interconnect electrodes has been revised and clarified to permit “exposed” piping to include short sections passing perpendicular through walls, floors or ceilings.

Section 250.53(G). Ground rods should be driven. The preferred method is perpendicular to the ground surface, followed by driving at up to a 45-deg angle from the ground surface. Burial in trenches is a third (last) choice after attempting to drive a rod at an angle of up to 45 deg from vertical and encountering rock bottom.

Section 250.56. Water pipes are required to be supplemented by another electrode. If a ground rod is used and the ground rod resistance to ground exceeds 25 ohms, that ground rod must be supplemented. It cannot be supplemented with a water pipe.

This removes the unintended, apparently circular reference in the 1999 Code that permitted a water pipe and a ground rod to supplement each other. The supplementary electrode(s) for a water pipe are required to be able to function adequately without the water pipe.

Section 250.64(C). This clarification explains that busbars may be connected together (spliced) to form a grounding electrode conductor. Busbars may not be used to splice other types of conductors unless the splices are made with exothermic welding or irreversible compression connections.

Section 250.97, Exception. Fittings used for bonding around concentric or eccentric knockouts must be identified for the purpose in addition to being listed.

Section 250.102 (E). Equipment bonding jumpers longer than 6 ft are permitted at outside pole locations where installed outside a raceway for bonding isolated metal sections or exposed risers.

Section 250.104 (A)(1) through (3). The requirement for bonding interior metal water piping has been expanded to cover water piping attached to the building exterior. Also, the bonding conductors used to connect to the water piping at separate (multiple) buildings are to be sized from Table 250.66 rather than from 250.122.

Section 250.104 (A) Exception. A separate jumper from a separately derived system to a local water pipe is not required if the building steel is used as the electrode and the water pipe is bonded to the building steel in the area served by the separately derived system.

Section 250.104 (B) and (C). The requirements for bonding gas piping revert to the rules of the 1996 NEC which treated gas piping as “other metal piping” (other than water). The equipment grounding conductor associated with the equipment that may energize the gas piping may also be used for bonding the gas pipe. Gas piping is now specifically mentioned under the rules for other metal piping.

Section 250.114(3). Kitchen waste disposers have been added to the list of cord- and plug-connected equipment that must be grounded in residential occupancies. Waste disposers not connected by cord and plug are covered under Section 250.110.

Section 250.118. “Aluminum or copper-clad aluminum conductors” replace “other corrosion-resistant conductors” as types of conductors that may be used for equipment grounding. Type MC cable must be listed and identified for grounding and must rely on a combination of the metal cladding and an included grounding conductor. Auxiliary gutters listed for grounding were added to the previously mentioned metal raceways that are suitable for grounding because auxiliary gutters are not considered to be raceways.

Section 250.120(B). Aluminum and copper-clad aluminum equipment grounding conductors are permitted subject to the same restrictions that apply to grounding electrode conductors. The restrictions, no terminations within 18 in of earth, not in direct contact with masonry or earth and not subject to corrosive conditions, have been added to this section rather than referring to the requirements for grounding electrode conductors.

Section 250.122(B). Where ungrounded conductors are increased in size for any reason, not just for voltage drop, the equipment grounding conductors must be increased in size proportionally based on circular mil areas.

Section 250.146 (A). Bonding of a receptacle grounding terminal to a box by direct yoke-to-box contact is now limited to surface boxes.

Section 250.148. Equipment grounding conductors other than isolated grounding conductors must be attached to boxes they pass through, but only where the circuit conductors are spliced or terminated on equipment within or supported by a box. Thus, junction and outlet boxes are still covered, but pull boxes without splices or terminations are no longer covered by this rule.

Section 250.184 (D). A new subsection provides minimum requirements for “multigrounded neutral conductors' where they are used in systems over 1,000V. Requirements cover neutral sizing, locations and spacing of electrodes and grounding of cable shields.


A new article has been added to cover the installation of Transient Voltage Surge Suppression (TVSS) devices. This article was added to provide installation requirements for a type of equipment that is seeing expanded use in all occupancies, and to differentiate between TVSS devices and the Surge Arrestors covered by Article 280.

To be continued next month.


Noel Williams is licensed as an electrical inspector in Utah and licensed as a master electrician in Utah, Wyoming and Colorado. He's also co-author of the NFPA's 1999 NEC Changes.

Dann Strube is a nationally recognized NE Code expert and electrical Code consultant. He's a certified electrical inspector in Indiana.

Gregory P. Bierals is president of the Electrical Design Institute. He presents seminars nationwide on NEC subjects.