Under-floor heating
We installed under-floor heating in an apartment complex in each foyer/entryway. These are not installed in kitchens or bathrooms. The electrical inspector informed us that GFCI protection is required, but there is no reference in Section 210.8. Is it required?

Yes, GFCI protection is required. See Section 424.99, which contains requirements for electric radiant heating systems installed under floor coverings. Section 424.99(B)(5) requires GFCI protection above and beyond the requirements found in 210.8. Additionally, all electric baseboard heaters, heating cables, duct heaters and radiant heating systems must be listed and labeled.

Ceiling fan in bathrooms
Is part of a ceiling fan blade permitted to be within 3 feet of a bathtub rim? Notes on drawings state nothing is permitted in a zone measured 3 feet horizontally and 8 feet vertically from the top of the rim. The condo baths are all the same, and we estimate that 1 foot of the fan blades will enter the space. Is that permitted?

See Section 422.18(B), which prohibits “metal parts” of a ceiling fan in bathrooms and shower spaces inside of a zone measured 3 feet horizontally and 8 feet vertically from the top of the bathtub rim. It is likely that the ceiling fan blades are nonmetallic, meaning that they are permitted to enter that zone.

Pool pump motor replacement
Last year, we replaced a three-phase 208V pool pump motor, protected at 40A, that had failed in a hotel pool. In our state, all commercial pools must be inspected once every three years. The inspector noted that the pool pump motor was replaced and GFCI protection was required. Is that correct for a three-phase pump?

Yes, Section 680.21 contains requirements for motors associated with pools. Pool pump motor replacements are specifically addressed in 680.21(D), which requires repaired or replaced pool pump motors to have GFCI protection in compliance with 680.5(B) or (C). In this case, 680.5(B) applies and requires GFCI protection of receptacles and outlets (hard-wired pump motors) on branch circuits rated 150V or less to ground and 60A or less, single- or three-phase.

Natural gas for standby generator?
On a design-build project, we proposed a generator for emergency power to be supplied with natural gas. During plan review, it was noted that this was not acceptable. Why would natural gas not be permitted? Why would we need a diesel-powered generator?

Part III of Article 700, Emergency Systems, contains requirements for emergency power sources. Section 700.12(C) requires that the emergency power source be suitably rated and have the capacity to supply and maintain the total load as determined by the design of the emergency distribution system. 

Section 700.12(C)(1) requires the emergency standby source to have an on-site fuel supply sufficient for not less than two hours of operation. The use of a public gas system is addressed in Section 700.12(C)(3), requiring that the emergency standby source not be solely dependent on a public utility gas system. There is an exception that would permit a public gas system to be recognized as the fuel supply for the emergency source only where the authority having jurisdiction agrees there is a low probability of simultaneous failure of the public gas system and normal source of power from the electric utility. This requirement exists because first responders will remove the electric utility and natural gas supplies in a fire situation. While first responders will remove public gas supply and normal power (utility service) from a burning building/structure, they will not remove the diesel supply to an on-site standby generator.

Type SER at 60°C?
In a Type III-constructed apartment complex, are SER cables used as feeders in insulated walls limited to 60°C ampacity?

No, see Section 338.10(B)(4). In general, where used as branch circuits or feeders, Type S, service entrance cable used for interior wiring must meet the installation requirements of Part II in Article 334. However, 338.10(B)(4)(a)(1) specifically excludes Section 334.80, which limits the application of types NM cable to ampacities that do not exceed those for 60°C conductors. It is important to maintain space between the SER cables, or the conductor ampacities must be adjusted for more than three current-carrying conductors in accordance with Table 310.15(C)(1); see 338.10(B)(4)(a)(2). While it is not likely you are installing Type SE cable with ungrounded conductor sizes 10 AWG and smaller, where these smaller conductors are installed in contact with thermal insulation, the conductor ampacity is limited to 60°C after any adjustment and correction factors.

Sashkin / stock.adobe.com