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Thread: Emergency Lighting on Generator

  1. #1
    Join Date
    Aug 2015
    Location
    Cincinnati, OH
    Posts
    356

    Emergency Lighting on Generator

    I'm going to try to explain this to the best of my ability. See attached sketch for reference -

    I have always worked with individual lights/exit signs with internal battery packs so this is a new area for me. I'm searching through 700 and trying to get an answer for my question, but no luck as of yet. Is a set up like this permissible per code?

    Basically the idea is to serve an emergency panel from a genset and ATS. In the example I'm showing normal lighting in a room fed from a separate panel (panel A) and a dedicated emergency circuit coming from the emergency panel (panel X).
    The potential issue I see with this is that if you lose power somewhere downstream of the ATS or downstream of panel X (EM branch circuits), that would be a way in which you would not be guaranteeing egress lighting in these areas. So then if you lost the normal lighting circuit in that area you would have a situation where there would be no lighting at all. Is this just accepted in the code as a "that's a very unlikely situation" or is this not allowed per code?

    Can someone offer any clarification or point me in the right direction here?

    Thanks,
    - Drew
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    Where sin increased, grace abounded all the more
    Rom 5:20

  2. #2
    Join Date
    Nov 2017
    Location
    Colorado & New Mexico
    Posts
    6
    I don't see a code problem with that setup. The no-lights situation you describe would require two separate circuit failures to happen within the 90 minutes you're required to provide egress lighting.

    Side note - if your generator is providing the only emergency power to a life safety load (like egress lighting), it needs to meet performance standards for a "Level 1" power source as defined in NFPA 110. Nothing too exotic in there, but mention it to your generator supplier.

  3. #3
    Join Date
    Jun 2003
    Posts
    6,727
    That would be a typical setup for emergency lighting. Odds are a failure won't happen on both the emergency side and the normal side at the same time.

    In addition to the comment about the generator and ATS being a Level 1 system, you won't be able to put any non-emergency loads on that ATS.

    If the client wants any non-emergency loads backed up (any receptacles, computer UPS's, heating or AC, or almost anything besides the exit and emergency lighting or the fire alarm panel) you will need to add a second ATS.

  4. #4
    Join Date
    Feb 2004
    Location
    Austin, TX
    Posts
    121
    It's just as likely that your battery back up lights will fail as the scenario you described, in fact, we recently had a utility power outage and therefore, many employees did not leave the building and the batteries failed within 1-1/2 hours as expected but nonetheless, the employees who stayed behind were complaining that the emergency lights had went out!
    Ken
    Electrical Project Coordinator


    "Communication, its a wonderful thing, when it happens."

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