More of What’s Changed for Article 100: Accepting (NEC) change, part 4

By Mark Earley | May 15, 2022
Illustration of a gray circuit box against an orange background. Image by / Andre Nery.
There is still more to report on in Article 100. As you look through the 2023 National Electrical Code — or review the first and second draft reports online—you will see there were many definition changes.




There is still more to report on in Article 100. As you look through the 2023 National Electrical Code — or review the first and second draft reports online—you will see there were many definition changes. However, most changes do not move the needle because they are simply editorial improvements. I won’t cover those unless there is a compelling reason that I believe makes it worthwhile.

Ground-fault circuit interrupter, special purpose. Class A GFCI protection is used on circuits of 150V or less to ground and 60A or less, single-phase and three-phase to protect receptacles and outlets. Class A GFCIs trip at 4–6 milliamperes (mA). They are the class that provides protection for personnel. Class C, D and E trip at 15–20 mA.

Class C GFCIs are for use on circuits over 150V to ground with a maximum line-to-ground voltage of 300V. In addition, either double insulation or reliable equipment grounding must also be provided. They can be used on systems operating 480V line-to-line.

Class D GFCIs are used on circuits with one or more conductors operating at over 300V to ground. They are required to have a larger-sized equipment grounding conductor to provide a low-impedance path to ground to ensure the voltage across a human body will not exceed 150V.

Class E GFCIs are also for use on circuits operating at over 300V to ground. However, they have a high-speed tripping device, which negates the need for an oversized equipment grounding conductor.

Special purpose GFCIs will be required for a number of applications where the voltage to ground exceeds 150V.

Some terms have been used in the NEC for decades without definitions. The 2023 Code rectifies that in several instances.

Ground-fault detector-interrupter. Section 690.41(B) requires ground-fault detector-interrupter (GFDI) protection of photovoltaic (PV) DC circuits that exceed 30V or 8A. Smaller systems consisting of two modules in parallel do not require GFDI protection. A GFDI is designed to provide protection from fires involving PV DC circuits. There have been several fires involving PV systems at retail locations.

Hazardous (classified) location. It seems odd that this term has been used in the NEC for decades and in other NFPA codes and standards without an official definition. Yet, the specific classes have been defined. In Article 100, the new definition is stated as “locations where fire or explosion hazards might exist due to flammable gases, flammable liquid-produced vapors, combustible liquid-produced vapors, combustible dusts, combustible fiber/flyings, or ignitable fibers/flyings.” This definition can be used with the class/division and zone classification systems.

Industrial mobile cable, Type IM. This cable type was introduced during the 2020 NEC cycle as Type P cable. Its requirements could be found in Article 337. During the first draft stage for the 2023 cycle, the cable was also given the name “drilling rig cable,” which reflected the cable’s original application. During the second draft stage, a decision was made to rename it “industrial mobile cable” because its application had been broadened well beyond drilling rigs in some applications in Class I, II and III locations, as well as some zone applications. It is also permitted in other applications.

Industrial installations, supervised. The term “supervised industrial installation” has been used in the NEC for several cycles. It has been used to allow different, often relaxed requirements for facilities that met certain conditions. In the past, it has applied where “conditions of maintenance and engineering supervision ensure that only qualified persons monitor and service the system.”

A new definition was added to Article 100 to establish what constitutes such an installation. The additional criteria includes an industrial process load or manufacturing process load of at least 2,500 kilovolt-amperes. The facility must have at least one service that operates at more than 150V to ground and more than 300V phase-to- phase. The existence of the definition makes it unnecessary to state the terms every time a rule requiring supervised industrial installations is stated. This definition only applies to Article 240.

Inverter, multimode. Inverters are an element of renewable energy systems, including PV, wind power and energy storage systems. Their primary role is to convert DC to AC. Most inverters are interactive, meaning that they operate in parallel with the utility. Multimode inverters are interactive with the utility, but they can also operate in island mode, which happens when they separate from the utility and continue to provide output power.

Likely to become energized. This term was used in a number of places in the NEC without a definition. It clearly required some judgment to make the decision. Oddly, there was guidance on the use of the term in the NEC Style Manual. The new definition is, “Conductive material that could become energized because of the failure of electrical insulation or electrical spacing.”

Some definition changes in the 2023 Code are simply editorial improvements.

Location, wet. This definition really didn’t change. However, it is a simple example of how lists can be used to state definitions or requirements more clearly. This definition is: “A location that is one or more of the following:

  • Unprotected and exposed to weather
  • Subject to saturation with water and other liquids
  • Underground
  • In concrete slabs or masonry in direct contact with the earth”

Microgrid, health care. The term “microgrid” has been used in the NEC for a couple of cycles. “DC microgrid” was defined in Article 712 last cycle. However, the term microgrid was used in Article 710 for standalone or islanded systems without a definition. A new definition of microgrid was added to Article 100 for this cycle. A new definition was also added for healthcare microgrids. This definition was extracted from the 2021 edition of NFPA 99, Health Care Facilities Code. Healthcare facilities have more detailed power supply requirements than other occupancies covered by the Code. If a healthcare microgrid is used as the primary power supply, it is not permitted to also serve as the alternate power supply.

Microgrids are permitted to supply the essential electrical system. They are also permitted to supply nonessential loads and to share distributed resources with the normal system as long as a failure of the normal system will not compromise the essential electrical system.

Panelboard and panelboard, enclosed. There has been an existing definition of panelboard in Article 100, which is under the jurisdiction of CMP-9. At the first draft stage, CMP-9 made two revisions to the definition. The first revision recognized that panelboards could be placed into other types of enclosures besides cabinets and cutout boxes. The second change was intended to address floor-mounted appliance outlet centers.

By the second draft meeting, the panel realized that the language they adopted for the floor-mounted commercial appliance centers presented a potential conflict with the prohibition of mounting panelboards in the face-up position in 408.43. Starting with this cycle, panelboards are now also prohibited from being mounted in the face-down position. So, the only change retained was for the expansion of the enclosure types.

Meanwhile, CMP-1 dealt with sections 110.16, Arc Flash Hazard Warnings; 110.26, Spaces About Electrical Equipment; and 110.28, Enclosure Types. Sections 110.16(A), 110.26(A)(1)(c), 110.26(A)(3), Exception No. 2, 110.26(D) and 110.28 were revised to recognize that these requirements only apply to those panelboards that are enclosed in a cabinet, enclosure or cutout box. CMP-1’s meeting was held after CMP-9’s meeting. Since “enclosed panelboard” was a new term, CMP-1 created a new definition for it at the first draft stage to clarify. The Correlating Committee reassigned the term to CMP-9 for the second draft stage so that panel would have jurisdiction over both terms.

Receptacle, weight supporting ceiling (WSCR). Plug-and-play permanently installed lighting was introduced in the 2017 Code . At that time, The WSCR and weight-supporting attachment fitting (WSAF) were referred to in 314.27(E) and 422.18 as “locking support and mounting receptacle, and a compatible factory installed attachment fitting designed for support.”

These new generic names, WSCR and WSAF, are intended to provide a more descriptive name and acronym for the receptacle type and the attachment fitting. A WSCR is required in 314.27(E) to be a listed device. However, the WSAF is required to be a recognized component of a listed luminaire or paddle fan. As a recognized component, it is not purchased separately for assembly to a luminaire; it is supplied by the luminaire or paddle fan manufacturer as part of the fixture.

Servicing. The 2017 Code introduced reconditioning for the first time. However, a definition for “reconditioned” was not introduced until the 2020 Code , along with a number of new rules that permit or prohibit the reconditioning of various types of equipment. The new rules in 2017 and the increased attention on reconditioned equipment in the 2020 edition raised a number of questions about how reconditioning differs from maintenance and repair of electrical equipment.

Header image by / Andre Nery.

About The Author

EARLEY, P.E., is an electrical engineer. Retired from the National Fire Protection Association, he was secretary of the National Electrical Code Committee for 30 years and is president of Alumni Code Consulting Group.





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