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Thread: Another Emergency Lighting Thread

  1. #1
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    Another Emergency Lighting Thread

    AHJ is requiring us to install emergency lighting in a classroom at a school. I'm not sure that the IBC requires it, but I'm not fighting that. The building has a generator. The owner wants to switch the one emergency fixture with the rest of the fixtures in the space (makes sense). Normally I would use a Bodine GTD or similar, but having re-read NEC 700, 700.25 doesn't seem to allow the transfer from normal to emergency power at the fixture. I've also found that the spec sheet for the GTD is a dead link on Bodine's Website (maybe a coincidence). I was told to look at using an IOTA ETS. This device powers the fixture from the emergency circuit and never the normal circuit, and will allow you to bypass the switch input, but it looks like I'll need a separate switch just for this one emergency light.

    How are you guys handling instances where there is just one emergency fixture in a space?

    Sorry for the lengthy post, thanks.

  2. #2
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    The more they overthink the plumbing, the easier it is to stop up the drain

  3. #3
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    Quote Originally Posted by dkidd View Post
    I did read through that, the BCELTS seems like overkill for a single fixture. I'd need one for every instance I have a single fixture in a space as emergency. AHJ is making us use them in toilets/workrooms/clasrooms/offices(its crazy). Maybe I'm wrong, and this is what the industry has been forced to use.

    Just came across the wattstopper ELCU-200, i think that would work and satisfy Art. 700. Its meant for up to 20A but I think use on a single fixture would be ok.

  4. #4
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    Is the owner against simply using a battery backup fixture per NEC 700.12? If the generator serves emergency lighting it must also be classified level 1 per NFPA 110.

  5. #5
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    Quote Originally Posted by LIM View Post
    Is the owner against simply using a battery backup fixture per NEC 700.12? If the generator serves emergency lighting it must also be classified level 1 per NFPA 110.
    ^^^^^That right there will send the generator cost through the roof. Even worse, if you already have a generator, now you'll have two.

  6. #6
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    Battery backup

    New to this not sure how to post a new thread but ... Was wondering if I need to run two separate conduits for emergency lights that are running off a battery backup inverter not a generator?

  7. #7
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    Quote Originally Posted by B4097 View Post
    New to this not sure how to post a new thread but ... Was wondering if I need to run two separate conduits for emergency lights that are running off a battery backup inverter not a generator?
    Unless there is a local or contract requirement, why is anyone using a generator or inverter to run e-lights? For example, what triggers the generator or inverter to kick the lights on? You don't always have a total building blackout. If you lose lights in part of the building how does the gen/inverter supply only that part of the building? This is why battery backup e-lights are supposed to be wired on the lighting circuit that serves the area they cover.

  8. #8
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    Quote Originally Posted by gadfly56 View Post
    Unless there is a local or contract requirement, why is anyone using a generator or inverter to run e-lights? For example, what triggers the generator or inverter to kick the lights on? You don't always have a total building blackout. If you lose lights in part of the building how does the gen/inverter supply only that part of the building? This is why battery backup e-lights are supposed to be wired on the lighting circuit that serves the area they cover.
    Say you're an owner of a building/campus with 500+ emergency fixtures, would you rather have 500+ battery packs to maintain or one genset/transfer switch. The expense of replacing battery packs every, idk, 5years can add up. Secondly, with a genset, you can expect full light output from emergency fixtures (battery packs typically don't run fixtures at full light output), hopefully reducing the sheer number needed.

    Generally speaking, emergency fixtures will have a device that senses the presence of normal power, when the normal power circuit is lost the device bypasses the switch state and says, turn on. If you loose power on any branch circuit feeding lighting, the emergency fixtures in that area would override the switch state and turn on, as they are powered by an emergency circuit. The emergency circuit is fed from a transfer switch (transfer switch is fed by normal power and backed up by genset). Transfer switch tells genset to turn on when normal feed is lost.

    That's a quick and dirty explanation, I'd suggest a google search.

  9. #9
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    Quote Originally Posted by IMFOTP View Post
    Say you're an owner of a building/campus with 500+ emergency fixtures, would you rather have 500+ battery packs to maintain or one genset/transfer switch. The expense of replacing battery packs every, idk, 5years can add up. Secondly, with a genset, you can expect full light output from emergency fixtures (battery packs typically don't run fixtures at full light output), hopefully reducing the sheer number needed.

    Generally speaking, emergency fixtures will have a device that senses the presence of normal power, when the normal power circuit is lost the device bypasses the switch state and says, turn on. If you loose power on any branch circuit feeding lighting, the emergency fixtures in that area would override the switch state and turn on, as they are powered by an emergency circuit. The emergency circuit is fed from a transfer switch (transfer switch is fed by normal power and backed up by genset). Transfer switch tells genset to turn on when normal feed is lost.

    That's a quick and dirty explanation, I'd suggest a google search.
    Yeah, but that's not how it works. Nobody subdivides the emergency lighting circuit to follow the lighting plan. Central systems are all-or-nothing affairs. And it matters how you detect loss of lighting. Or, in fact, for UPS style systems the emergency power is always on and utilizes existing lighting fixtures that are designated as "emergency". They are unswitched and never go off. So, instead of 500 discrete units you have conversion losses, battery maintenance, and power consumption to consider.

  10. #10
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    Quote Originally Posted by gadfly56 View Post
    Yeah, but that's not how it works.
    uh, yes it is. If “nobody follows the lighting plan”, that’s on you, my jobs we follow it. The constant “on” emergency fixtures are antiquated and i’d say certainly not appropriate in a lot, if not most spaces. GTDs have been around for what, 20 yrs(?) at least, that’s how I’d sense loss of power and bypass switching. No reason to burn those lights 24/7.

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