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Friday, July 15, 2022
Question:
Hello CQD,
In a three-story building, there are lights in the stairs and corridors that are each supplied by a circuit from an emergency panel backed by a generator. These lights and circuits are the only sources of illumination in these areas. The generator will automatically come on line in loss of power. Does this meet the intent of article 700.17 of the NEC?
Chuck Prado
A
Answer:
Hello Chuck,
The installation described appears to meet the requirements of Section 700.17 and 700.18. However, there is important information in Section 700.16(B) regarding reliability. This section indicates that Emergency lighting systems shall be designed and installed so that the failure of any individual lighting element, such as the burning out of a lamp, cannot leave in total darkness any space that requires emergency illumination. Control devices in the emergency lighting system shall be listed for use in emergency systems. Listed unit equipment in accordance with 700.12(F) shall be considered as meeting the requirements of this section. Often in stairways wired as you described, unit equipment is sometimes installed to maintain the lighting in the stair until the emergency illumination from the generator is provided after a short delay of transfer.