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 2026 NEC.

Bonding more than 250V to ground

We are having a debate on the job over bonding. Does a 480/277V feeder require bonding locknuts?

In general, Section 250.97 requires the electrical continuity of metal raceways and any cables with metal sheaths containing other than service conductors be ensured by one or more of the methods specified for services in 250.92(B), except for the permission to bond equipment to the grounded service conductor. However, there is an exception that applies where oversized, concentric or eccentric knockouts are not encountered, or if a box or enclosure with concentric or eccentric knockouts is listed to provide a reliable bonding connection. In these cases, reliable bonding can be achieved by standard threadless couplings and connectors, two locknuts on RMC/IMC with one inside and one outside of boxes and cabinets, or fittings with shoulders that seat tightly against the box or cabinet (such as EMT connectors, FMC connectors and cable connectors), with one locknut on the inside of boxes and cabinets, and other listed fittings.

Required receptacle outlet

Why does the NEC require a receptacle outlet near an outdoor swimming pool? It seems to go against the idea of keeping anything electrical from energizing the pool frame or water.

The requirement you are referencing is in Section 680.22(A)(1) and applies to permanently installed pools. At least one 125V, 15A or 20A receptacle on a general-purpose branch circuit must be located not less than 6 feet from, and not more than 20 feet from, the inside wall of the pool and must not be placed more than 6½ feet high. This requirement is safety­-driven. It allows for pool maintenance with a readily accessible GFCI-protected receptacle; see 680.5. Additionally, the placement of this receptacle is designed to facilitate the use of electrical appliances such as a radio from a safe distance. Without this requirement, the nearest receptacle may be indoors. Users of the pool would then be likely to use an extension cord, which could easily reach into the pool, or plug it into a receptacle without GFCI protection.

Feeder or branch circuit?

The installation of a chiller unit has us a bit confused. The drawings note it as a feeder in the schedule. The same schedule has notes stating the primary conductors to transformers are branch-circuit conductors. Is that true? I have always had a problem applying the definitions as they rely on other definitions. Is there an easy way to identify conductors quickly and accurately?

The answers to your questions on how to identify the NEC conductor types are found in the definitions in Article 100. It is imperative that the code user understand conductor types. Branch circuits are the circuit conductors between the final overcurrent protective device (OCPD) protecting the circuit and the outlet or outlets supplied. An outlet is any point on a wiring system where current is taken to supply utilization equipment. The defined term “equipment” includes utilization equipment and other equipment that does not use electrical energy but is necessary to facilitate that function.

For example, fittings, devices, appliances, luminaires, apparatus and machinery are equipment, but fittings and devices do not use electric energy for electronic, electromechanical, chemical, heating, lighting or similar purposes. A transformer is equipment, either single-phase or polyphase, that uses electromagnetic induction to convert current and voltage in a primary circuit into current and voltage in a secondary circuit. Transformers do not use energy. They are, however, essential to facilitate the use of electrical energy at utilization voltages.

Service conductors start at the service point and end at the service disconnecting means. The service point is where the utility company ends and conductors under the scope of the NEC begin. The service equipment consists of a disconnecting means as required in 230.70 and an OCPD, which is required to be an integral part of the service disconnect or located immediately adjacent as required in Section 230.91. A disconnecting means that opens service conductors without an OCPD is not a service disconnect; it is simply an isolation switch.

A feeder is defined as the circuit conductors between the service equipment, the source of a separately derived system or other power supply source, and the final branch-circuit OCPD. For example, service conductors may terminate in a service disconnect (circuit breaker) in a switchboard. From there, feeders may supply panelboards, which then supply branch circuits. From that same switchboard, a 400A OCPD may supply a chiller unit, and those conductors would be a branch circuit.

The feeder definition can be confusing with respect to transformers. The defined term “feeder” includes circuit conductors between the source of a separately derived system and the final branch-circuit OCPD. This may seem to infer that the primary conductors are branch circuits, but they are not. They are feeders, as they do not supply utilization equipment and do not terminate at the final branch-circuit OCPD.

The NEC defines transformer secondary conductors as originating at the secondary winding terminals of a transformer. In general, transformer secondary conductors are tap conductors and must comply with 240.21(C). Only where the requirements of 240.21(C)(1) are applied could the transformer secondary conductors be permitted to be protected by the primary OCPD. This is an unusual scenario, applying only to transformer secondary conductors supplied by the secondary side of a single-­phase transformer having a 2-wire (single-voltage) secondary, or a three-phase, delta-delta connected transformer with a 3-wire (single-voltage) secondary. In general, this means that all wye-­connected transformer secondary conductors must follow the tap rules in 240.21(C).

AFCI/GFCI required?

A bathroom renovation in a home will include a towel bar at 120V and an in-wall electric heater at 240V. Both are to be hard-wired. The heater is 6 feet away from the shower and the towel bar is 3½ feet away. Do they require AFCI and GFCI protection?

In general, GFCI protection is not required by the NEC for hard-wired towel bars or electric heaters. Section 210.8 requires 125V through 250V receptacles supplied by single-phase branch circuits in the locations listed to be provided with GFCI protection. GFCI protection requirements for specific appliances in 210.8(D) do not reference towel bars or electric heaters. AFCI protection requirements in Section 210.12(B) are limited to 120V, nominal, single-phase, 10A, 15A and 20A branch circuits supplying outlets or devices installed in the 14 list items provided. Bathrooms are not listed, so AFCI protection is not required for the towel bar or heater.

It is extremely important to review the installation instructions for the towel bar and heater. Some manufacturers may require GFCI protection when this equipment is installed in a bathroom. If that is the case, Section 110.3(B) will require GFCI protection.

Unobstructed egress

The installation of a 208/120V, 1,600A service was found noncompliant by the inspector. The electrical equipment room has only one door. However, the engineer noted on the drawings that there was unobstructed egress and a single door was permitted. The inspector is telling us that we need 12 feet of room from the face of the equipment to the opposite wall to have unobstructed egress. Is that correct?

No, the inspector has misapplied this requirement. The general rule is that large equipment (over 6 feet wide and 1,200A or more, or service disconnects where the combined ampere rating is 1,200A) requires one entrance to and egress from the required working space at each end of the working space. Two permissive rules allow for a single door. The first is unobstructed egress. This simply means that there is a continuous and unobstructed way of egress out of the room and there are no obstacles such as transformers to get around. There is no minimum distance. All requirements of 110.26 for workspace clearance must be met. The second permissive method applies where the depth of the working space is twice that required by Section 110.26.

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