Jim Dollard has an extensive background in codes and standards. Send questions about the National Electrical Code (NEC) to Jim at [email protected]. Answers are based on the 2023 NEC.

Warning signs required?

During the final stages of a large commercial project, a consultant told us that warning signs must be added to the door for each electrical equipment room. Is that an NEC requirement?

No, see Section 110.27(C) that requires all entrances to rooms and other guarded locations that contain “exposed live parts” to be marked with warning signs that permit entry to only qualified persons. This warning requirement applies only in very old installations that may still have exposed live parts and areas such as utility (service) vaults inside a privately owned structure that may include exposed live parts supplying single-phase transformers in a three-phase arrangement.

Electric pool water heaters

Does a hard-wired 240V, 30A, all-electric pool water heater require GFCI protection? We are getting conflicting answers from enforcement agencies; it seems they do not understand Article 680. It is an in-ground pool behind a dwelling unit. Article 680.28 applies only to gas heaters, right?

Because the electric pool heater in question is outside of a dwelling unit, your answer is located in Chapter 2 and not Article 680. It is important to keep in mind the arrangement of the NEC as provided in Section 90.3. The NEC is logically divided into the introduction and nine chapters. Chapters 1, 2, 3 and 4 apply generally, meaning they apply everywhere, in dwellings, marinas, hospitals, hazardous locations and much more. Chapters 5, 6 and 7 apply to special occupancies, special equipment or other special conditions and may supplement or modify the requirements in chapters 1–7.

The GFCI requirements in 210.8(F) apply only to dwelling units. This requires outdoor outlets, such as this pool heater, where supplied by single-phase branch circuits rated 150V or less to ground, 50A or less, be provided with GFCI protection. This requirement applies to cord-and-plug-­connected units and those that are hard wired. 

Remember, an outlet is defined as a point on the wiring system at which current is taken to supply utilization equipment. With respect to specific Article 680 requirements, all-electric pool water heaters are addressed in the general requirement in 680.10(A), but no GFCI requirement exists there. In Part II for permanently installed pools (as noted in your question), Section 680.28 requires all circuits supplying gas-fired swimming pool and spa water heaters operating at voltages above the low-voltage contact limit to be provided with GFCI protection.

Protection from inadvertent contact

We installed over a dozen transformers on a commercial installation. In each case, the inspector flagged us for the lack of barriers on the main circuit breaker in each panelboard supplied. Is that right? I thought that was only for residential services, but he said it was a feeder requirement. Do we need this for all feeders?

The inspector is correct; see Section 215.15. The requirement is for barriers to be placed such that no energized, uninsulated, ungrounded busbar or terminal is exposed to inadvertent contact by people or maintenance equipment while servicing load terminations in panelboards, switchboards, switchgear or motor control centers. 

It is important to note that this does not apply to all feeders. This requirement applies to the termination of feeder taps (240.21(B)) and transformer secondary conductors (240.21(C)). These conductors are not protected at their rated ampacity by the feeder overcurrent protective device or the primary overcurrent protection on a transformer. This is a safety driven requirement that recognizes the concept of electrically safe work conditions in NFPA 70E. This requirement now applies to all service supplied equipment (230.62(C)) as well as feeder taps and transformer secondary conductors.

ERMS

We installed a 1,200A electronic trip molded-case circuit breaker and adjusted it down to 1,000A. The inspector failed us due to the lack of arc energy reduction. We are at 1,000A and the Code does not require it, right? Is an energy reduction maintenance switch (ERMS) required?

The inspector is correct. A means of arc energy reduction is required. See the parent text of Section 240.87, which requires arc energy reduction for circuit breakers where the highest continuous current trip setting for which the actual overcurrent device installed in the device is rated “or can be adjusted” is 1,200A or higher. Here the circuit breaker can be adjusted to 1,200A. An ERMS is just one permitted method to achieve compliance. See 240.87(B). It is possible that the instantaneous trip setting or the override will operate at less than the available arcing current. Where this is the case, an engineer can perform those calculations and provide documentation to the inspector. 

Dry-type transformer ventilation

Can a 75 kVA dry-type transformer be placed up against drywall in a corner? It is the only spot on the floor in this electrical closet it will fit.

No, the transformer is required to be marked with the required clearances from walls. This is necessary to dispose of the transformer full-load heat losses without creating a temperature rise in excess of the rating. Perhaps there is space above in the electrical closet to hang the transformer and maintain the required spacing. Additionally, where the surface of the transformer is horizontal and readily accessible, signage or a label of some type must be placed on the flat surface to prohibit storage on top of the transformer, which would limit the dissipation of heat. See Section 450.9 for requirements on transformer ventilation.

Does everything need to be listed?

We have an inspector that wants every item in an electrical installation listed for the application. Is that required?

No, there is no blanket NEC requirement mandating that everything be listed. There are specific requirements scattered throughout the Code. They are primarily found in the XXX.6 section of an article, but many exist elsewhere. 

Two examples include 334.6 that requires Type NM and Type NMC cables and associated fittings must be listed and 410.6 requiring all luminaires, lampholders and retrofit kits be listed. Other specific listing requirements exist, such as those for supporting and securing cable assemblies. For example, see 330.30(A), which mandates MC cable be supported and secured by staples; cable ties listed and identified for securement and support; straps, hangers or similar fittings; or other approved means designed and installed so as not to damage the cable. Note that the only item required to be listed in this section are cable ties identified for securement and support.

Where a branch circuit begins

Hope you can solve a disagreement we are having about hospital-grade armored cable. I installed home run MC cable into a 12x12 junction box and took several receptacle branch circuits into medical exam rooms with hospital-grade armored cable. I say this is Code-compliant but my partner disagrees. Reading the hospital requirements, it sure looks like I am correct. Do you agree?

No, see Section 517.13, which requires all wiring that serves patient care spaces to comply with 517.13(A) and (B). Section 517.13(A) provides requirements on the permitted wiring methods. This section mandates that all “branch circuits” serving patient care spaces be provided with an effective ground-fault current path by installation in a metal raceway system or a cable having a metallic armor or sheath assembly. A “branch circuit” is defined (see Article 100) as the circuit conductors between the final overcurrent device protecting the circuit and the outlet(s). This means that the conductors from the panelboard or other distribution equipment containing the final OCPD to the receptacle outlets in the medical exam room must comply with all of the requirements in 517.13.

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