With respect to circuits exceeding 277V, nominal to ground, but not exceeding 600V, nominal between conductors, is it permitted to supply luminaires powered from direct-current (DC) systems (excluding exceptions)?

A) No, this is not permitted.
B) Yes, if luminaires contain a listed DC-rated ballast that provides isolation between the DC power source and the lamp circuit, and protection from electric shock when changing lamps.
C) Yes, if the luminaire contains a listed DC-rated ballast and has no provision for changing lamps.
D) Yes, if either condition outlined in (B) and (C) above is met.

Find the Answer

Answer: D

As noted in Sec. 210.6(D)(3) of the 2017 NEC, it is permitted if luminaires contain a listed, DC-rated ballast that provides isolation between the DC power source and the lamp circuit and protection from electric shock when changing lamps, or if the luminaire contains a listed, DC-rated ballast and has no provision for changing lamps.

Owen is the owner and president of National Code Seminars and the holder of master electrician certifications in 46 states. He can be reached at [email protected].