Food trucks and the NEC

We are a third-party electrical inspection agency and were contacted by a township official to inspect a food truck. Is this covered by the NEC? Is a food truck a recreational vehicle (RV)?

A food truck is not an RV. The NEC defines the latter as temporary living quarters for recreational, camping or travel use, which either has its own motive power or is mounted on or drawn by another vehicle.

Food trucks today typically have a standby generator to supply general power required to make coffee and operate small appliances. In Article 90, Section 90.2(C) outlines installations covered by the Code and 90.2(D) outlines installations that are not covered. Section 90.2(D) list item (1) clarifies that automotive vehicles other than mobile homes and recreational vehicles are not covered by the NEC. While a food truck is not covered, requirements for optional standby systems, GFCI protection and much more can be enforced by the local building officials and fire marshal. Additionally, there are many other requirements that may apply, including, but not limited to, NFPA 1, 58 and 96. See the NFPA’s “Food Truck Safety Fact Sheet.”

Bonding pool water?

Where a gunite (basically rebar with spray-on concrete) pool is installed with the unencapsulated rebar that is properly bonded, do we need another device to bond pool water?

No, according to Section 680.26(B)(1), a sprayed concrete type pool has a conductive pool shell requiring bonding of the rebar as described in your question. The conductive pool shell bonds the water. Section 680.26(C) for bonding the pool water applies only where none of the bonded parts specified in 680.26(B)(1) through (B)(7) are in direct connection with the water. Where there is not a conductive pool shell, or some other bonded metal in direct connection with the pool water, 680.26(C) requires an approved corrosion-resistant conductive surface that always exposes not less than 9 square inches of surface area to the water. There are many devices available to achieve this bonding requirement, and they are typically installed in the pool piping system or skimmer.

Does 517.13 apply?

In a limited-care facility (assisted living), are the patient bedrooms required to meet the redundant grounding requirements in 517.13? We are being told to wire that way, but it does not make sense. Also, where 517.13 applies, does that include communications systems? 

No, see Part II of Article 517. Section 517.10 significantly clarifies the applicability of Part II of Article 517, which contains requirements for wiring and protection, including 517.13. These requirements apply only to patient care spaces in healthcare facilities. 

Determining where Part II does not apply has created some confusion in the past. The NEC was modified to provide significant clarity on this. See 517.10(B) list item (2), which excludes spaces of nursing homes and limited­-care facilities wired in accordance with NEC chapters 1–4 where these spaces are used exclusively as patient sleeping rooms. Supplemental requirements or modifications of existing requirements for communications circuits in healthcare facilities are located in Part IV of Article 517. See Section 517.80, which clarifies that communications systems are not required to comply with the grounding requirements of 517.13.

460V motor at 480V?

Is it permissible to wire a motor marked 460V at 480V? I have never heard of a 460V system. Where can I find information on the voltages in the Code? 

Yes, motors marked 460V are designed to operate on 480V systems. The general requirement is that the voltage considered is that at which the circuit operates. See Section 110.4. For calculation of branch-circuit and feeder loads only, Section 220.5(A) lists nominal system voltages as 120, 120/240, 208Y/120, 240, 347, 480Y/277, 480, 600Y/347 and 600, unless other voltages are specified. 

NEMA standards assume a voltage drop of up to 4% from the nominal voltage for motors. In this case, 460V is a standard utilization voltage for motors and provides for a range of voltage fluctuation. The assumed 4% voltage drop for motors results in motor nameplates marked with utilization voltages. For example, Table 430.250 includes utilization voltages of 200V, 230V and 460V. If we add the assumed 4% voltage drop, we see the nominal voltages at 1.04 x 200 = 208, 1.04 x 230 = 239.2 (240) and 1.04 x 460 = 478.4 (480).

Limited-access working space

Where are the rules for working space above a lay-in ceiling? We just failed an inspection. This will be hard to comply with. 

The requirements you reference are in Section 110.26(A)(4) for limited access. This section applies to equipment in a space with limited access likely to require examination adjustment servicing or maintenance while energized. For example, duct heaters and VAV boxes would fall under this rule. 

In addition to the general requirements of Section 110.26, which include the depth, width and height of working space, 110.26(A)(4) provides permissive requirements for spaces with limited access. These requirements include permission to be above a lay-in ceiling, provided there is an opening not smaller than 22 inches by 22 inches, or in a crawl space with an accessible opening not smaller than 22 inches by 30 inches. This requirement also permits ceiling support structural members or access panels to be in the working space.

Listed FMC?

Is flexible metal conduit (FMC) required to be listed? I got red tagged for using nonlisted FMC because the inspector saw coils of new FMC that was not listed. This is what the supply house sent to the job site. Why do they make it if it cannot be legally installed?

See Section 348.6, which requires all FMC and associated fittings to be listed. There is no requirement that a manufacturer must list their products. A manufacturer may ship a product overseas where listing is not a requirement. It is imperative to request listed products from supply houses when there is a listing requirement in the NEC. If contractors are using nonlisted FMC, manufacturers will continue to sell it.

Number of circuit breaker enclosures?

Drawings for an industrial site note that several transformers are limited to not more than six circuit breakers on the secondary. We have eight small loads to supply and want to avoid a single overcurrent device and feeder taps. Is this an NEC requirement?

There is a limited amount of information provided in your question. It seems the transformer in question is being protected with primary and secondary overcurrent protection. Typical installations are provided with primary protection only, which is sized at 125% of the primary amps. It is permitted to use a larger overcurrent device on the primary (250%) where secondary protection is provided at 125% of the secondary amps. See Table 450.3(B). 

Where secondary protection is required, Table Note No. 2 applies. Table notes are enforceable, while informational notes are for informational purposes only. Table Note 2 permits not more than six circuit breakers or six sets of fuses grouped in one location from the transformer secondary. Where this is done, the total rating of the overcurrent devices (not more than six) cannot exceed the allowed value for a single overcurrent device. This means if the maximum secondary protection is required at 400A, the total value of circuit breaker or fuse ratings cannot exceed 400A. In all cases, transformer secondary conductors must be installed in accordance with 240.21(C).

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