EV chargers as a continuous load

Locally, we are being forced to use type MC cable to supply electric vehicle chargers because the full load amps of the EV charger, when at 125%, exceed the 60°C ampacity column for type NM cable. Many of these installations charge the car to 100% in under 3 hours. Why are we forced to consider them a continuous load?

The NEC defines a continuous load as one where the maximum current is expected to continue for 3 hours or more. This requirement applies globally throughout the Code. It is important to note that there are many requirements that specifically call out electrical equipment as a continuous load without respect to how long maximum current continues. See Section 625.42, which clearly requires that all EV charging loads be considered continuous for the purposes of Article 625 requiring conductor ampacity at 125% of the EV charging equipment rated full load amps.

Listed holiday decorations

Every year, a local organization puts out a Christmas display in a local park for residents. We volunteer every year to energize the displays and follow all of the rules for temporary power. This year, we were told by the electrical inspector that the handmade displays were not listed and could not be used. Political pressure permitted the holiday lighting to be energized throughout the holiday season. Was the inspector correct?

The inspector was correct. See Section 590.5, which requires that decorative lighting used for holiday lighting and similar purposes, in accordance with 590.3(B), be listed and labeled on the product. It is unfortunate that, in some cases, the safety-driven rules contained within the NEC are subverted for political purposes. Decorative holiday lighting is typically installed where the public has easy access to it. The listing requirement is necessary to protect people and property from fire and shock hazards.

Field evaluation of equipment

Why is a field evaluation of equipment required in one municipality or state but not in a neighboring area? We have installed recycling equipment, power distribution and controls made in Europe in many areas with no issues. Yet in other locales, we are made to jump through dozens of hoops that seem wholly unnecessary. What makes equipment listed? Why can’t the inspector make the call? Why involve a third party?

Equipment listing and certification requirements in the United States are completely different than those in other parts of the world. They are apples and oranges and cannot be intermixed in most installations without a field evaluation. The NEC requires all conductors and equipment to be approved; see Section 110.2. This means that the installation must be acceptable to the authority having jurisdiction (AHJ), which is typically the electrical inspector. An AHJ is an organization, office or individual responsible for enforcing the requirements of a code or standard or for approving equipment, materials, an installation or a procedure. 

While the NEC requires all conductors and equipment to be approved, there is not a blanket requirement for listing. Individual requirements exist throughout the Code, typically in the xxx.6 section such as 410.6, which requires all luminaires, lampholders and retrofit kits be listed. Where listed equipment is encountered, the internal wiring or construction of the equipment is not inspected at the time of installation unless alterations were performed or the equipment was damaged; see Section 90.7. 

Your question refers to the installation of recycling equipment, power distribution and controls, which affects a significant number of listing requirements in the NEC. Where an electrical inspector encounters such equipment, it is incumbent on them to require a field evaluation, which results in an applied field label. The electrical inspector would not have the equipment, the background/­experience or the capability of reviewing what could be hundreds of devices and their associated product standards. Additionally, they may only be performed by a field evaluation body meeting the qualification and competency requirements as outlined in NFPA 790. These third-party investigations include, but are not limited to, the considerations listed in 110.3(A). Attempting to justify an installation because it was approved in another area is not a basis for approval. 

Luminaires as raceway

In straight runs of tubed lighting fixtures that will be installed together, can we use the fixture as a raceway? The design has them supplied by two circuits with every other fixture on a different circuit.

Yes, see Section 410.64, which permits luminaires designed for end-to-end connection to form a continuous assembly to contain conductors of a two-wire branch circuit, or one multiwire branch circuit. Additionally, this section permits one additional two-wire branch circuit separately supplying one or more of the connected fixtures. They could be supplied with a single multiwire branch circuit or two separate branch circuits. 

Emergency feeders

An engineer is stating that NFPA 110 governs the installation of emergency feeders, requiring Type MI cable in all cases. It is our opinion that an emergency feeder installed in a fully sprinklered space is acceptable. Can you help?

The NEC has purview over the installation of emergency feeders. NFPA 110, Standard for Emergency and Standby Power Systems, contains requirements covering the performance of emergency and standby power systems providing an alternate source of electrical power to loads in buildings and facilities in the event that the primary power source fails. When dealing with different codes and standards, it is imperative to understand and properly apply the scope of each document. 

The scope of NFPA 110 in Section 1.1.1 is limited to power systems, including power sources, transfer equipment, controls, supervisory equipment and all related electrical and mechanical auxiliary and accessory equipment needed to supply electrical power to the load terminals of the transfer equipment. Note that the scope of NFPA 110 ends at the load terminals of the transfer switches. The permissive requirements in NEC Section 700.10(D)(2)(1) for feeders on the load side of the transfer switch installed in spaces or areas fully protected by an approved automatic fire protection system would apply.

Outdoor de-icing on GFCI?

An inspector failed us for using a two-pole GFCI circuit breaker to protect de-icing cable installed above gutters on a commercial roof. We had to purchase and install a circuit breaker marked GFPE. Is that correct? 

See Section 426.28, which requires ground-fault protection for fixed outdoor electric de-icing and snow-melting equipment with a trip level the manufacturer specified. It is typical for manufacturers of this equipment to require ground-fault protection trip levels at up to 30 milliamps (mA). A class A GFCI will trip when the ground-fault current is 6 mA or higher. Section 110.3(B) and 426.28 would apply, requiring compliance with the manufacturer specifications.

Extended stay hotel requirements

Do I need two small appliance circuits in a tiny kitchen with a cooktop in an extended stay hotel? It seems silly for a tiny kitchen countertop. There will be two receptacle outlets (different branch circuits) on 16 inches of countertop.

Yes, Section 210.17 requires all guest rooms or guest suites in hotels, motels and assisted living facilities with permanent provisions for cooking meet the rules for branch circuits in dwelling units. This includes, but is not limited to, the required 120V, 20A branch circuits in 210.11(C)(1) for small appliance branch circuits (two), (C)(2) for laundry area (if provided), (C)(3) for bathroom receptacle outlet(s) and required receptacle outlets in 210.52.

Is a multiwire branch circuit required?

During a renovation in the showroom of a lighting display area, we identified duplex receptacles supplied by two branch circuits instead of a multiwire branch circuit. The two single-pole circuit breakers did have a handle tie. Is that OK?

Yes, see Section 210.7, which requires that where multiple branch circuits supply devices or equipment on the same yoke or mounting strap, such as a duplex receptacle, a means to simultaneously disconnect the ungrounded conductors is required to be provided at the point at which the branch circuits originate. It is important to note that a “means to simultaneously disconnect” does not mean common trip (a two-pole circuit breaker). A multiwire branch circuit could have been used in this installation, but it is not required. Section 210.7 exists to ensure that when working on a device supplied by more than one ungrounded conductor, a single operation of the hand (a handle tie on two single-pole circuit breakers) will open both circuits at the source of supply. Similarly, where a multiwire branch circuit is used in any installation, a means that will “simultaneously disconnect” all ungrounded conductors at the point where the branch circuit originates is required by 210.4(B).

Common grounding electrode conductor

Where a service lateral will supply services (one location, four service disconnects) in four retail stores in a single structure, is it required to install individual grounding electrode conductors from the metal underground water pipe to each service disconnecting means? There is a service lateral and wireway, which will supply each service enclosure immediately above the wireway. There are no other grounding electrodes. The utility service connection and the metal underground water pipe are on opposite ends of the structure. 

A common grounding electrode conductor and taps are permitted. It is important to note that a single structure or building is, in general, permitted to have only one service. Where a structure is separated from adjoining structures by firewalls, the NEC recognizes multiple buildings, and a service to each building is permitted. 

Section 250.64(D) permits a building or structure with multiple disconnecting means installed in separate enclosures to use a common grounding electrode conductor and grounding electrode conductor taps. “Tap conductor” applies only in Article 240 and does not apply to the grounding electrode conductor taps or the service conductor taps into each individual service disconnecting means. The tap rules (240.21) do not apply. 

The common grounding electrode conductor (in this case from a metal underground water pipe) is required to be continuous [general rule in 250.64(C)]. The common grounding electrode conductor must remain without a splice or joint at each point it is connected to the grounding electrode conductor taps; see 250.64(D)(1). Where the only grounding electrode present is a metal underground water pipe, it is required to be supplemented with an additional electrode; see 250.53(D)(2). Any of the electrodes listed in 250.52(A)(2) (including ground rods) are permitted to supplement the metal underground water pipe electrode.

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