700.17 1&2 (Branch Circuit for Emergency Lighting)

[Greenboy]

I am curious to learn regarding article 700.17. It is not clear to me if we meet the intent of this code article. We have (1) circuit feeding lights in a stairwell, from a emergency panel, downsteam from an life Safety ATS. The panel is on during normal power, and when power is disrupted, the generator kicks on, transfer switch switches to gen power, and within 10 seconds, the panel comes back on line.

My view is I meet the intent of 700.17(1). Therefore, I do not need to meet the intent of 700.17(2).

However, I have been reviewing on line, and it appears that I do not meet the intent of the code, with different interpretations of that code.

The inspector is telling me that I need (2) circuits feeding the area in case 1 circuit fails, and leave the area dark.

Please help

 

[Danielt]

I agree that you don't meet this code.
I would think battery back-ups in the stairwell lights would comply with 700.17(1), per 700.12 F
Or putting every other light on a different circuit to comply with 700.17(2)

 

[Greenboy]

I do satisfy the 700.12 B (Generator Set) though. The Gen set has been programmed/tested to come on within 10 seconds per 700.12.

700.12 F would apply if I do not have the generator. Stated in 700.12, it states "The supply system for emergency purposes in addition to the normal services to the building and meeting the general requirements of this section, shall be one or more of the types of systems described in 700.12(A) through (E)."

700.17 (1) states - "An emergency lighting supply, independent of the normal lighting supply, with provisions for automatically transferring the emergency lights upon the event of failure of the normal lighting branch circuit." Am I not satisfying this code with the use of a transfer switch?

 

[MEngineering101]

I would say the ATS does not meet the "failure of the normal branch circuit,' as the ATS is probably only monitoring the utility feed and not each individual branch circuit. So if a branch circuit breaker in a panel were to trip, the ATS will not start the generator, or transfer power to an untripped circuit breaker. In my experience, only unit equipment, integral battery packs or central inverters can economically meet 700.17(1).

For stairwell lighting, our typical design approach is to evenly distribute the lighting load between one normal branch (occ sensor controlled) circuit and an emergency (night lighting) branch circuit. This meets the intent of 700.17(2). If energy code does not allow night lights, than an ALCR is specified on the emergency lighting circuit.