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Thread: Use Definite Purpose Contactor To Switch Different Voltages To LED High Bay

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    Use Definite Purpose Contactor To Switch Different Voltages To LED High Bay

    Hi --

    We're having an LED high-bay fixture installed that will operate on voltages from 110 to 277. The lighting in this particular area is wired for 120 volts, and is normally switched off at the end of the day.

    The stand-by emergency power available to us is supplied at 277 volts (which is what most of the fluorescent fixtures in our facility use).

    We'd like to have this fixture wired into the stand-by system. Is it legal to use a definite-purpose contactor to switch between the two different voltages, i.e., when the coil on the contactor is energized, the fixture receives 120, but with power-loss to the coil, to fixture receives 277?

    Any help is appreciated -- Cheers

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    I do not know the answer, never encountered this situation, but I am not liking this solution.
    "Electricity is really just organized lightning." George Carlin


    Derek

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    Quote Originally Posted by jumper View Post
    I do not know the answer, never encountered this situation, but I am not liking this solution.
    I don't see any major issue with it. I'd want to switch out the hot and neutral leads so you do not accidentally connect the neutral from one system to the neutral of the other.

    Use an IEC style contactor that has the contacts mechanically linked so if you get a welded contact the whole contactor will still switch or not switch.

    Whether it is a code legal solution is something else.
    Bob

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    Quote Originally Posted by petersonra View Post
    I don't see any major issue with it. I'd want to switch out the hot and neutral leads so you do not accidentally connect the neutral from one system to the neutral of the other.

    Use an IEC style contactor that has the contacts mechanically linked so if you get a welded contact the whole contactor will still switch or not switch.

    Whether it is a code legal solution is something else.
    You draw it, stamp it and I will install it.

    Code legal, safe, or anything else is your problem then as long as I do correctly.

    No problem.

    Else, no way I can endorse this solution.
    "Electricity is really just organized lightning." George Carlin


    Derek

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    Don't know if your LED driver is the same, but with multi-voltage fluorescent ballasts if you power it up with one voltage you can no longer use it on any other.


    -Hal

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    Why not reconnect the thing to 277 for normal power?

    If neutral is common to other 120 volt loads you should be separating that anyway if you want to run at both voltages, not that it won't "work" it just isn't code compliant.
    I live for today, I'm just a day behind.

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    Quote Originally Posted by kwired View Post
    Why not reconnect the thing to 277 for normal power?

    If neutral is common to other 120 volt loads you should be separating that anyway if you want to run at both voltages, not that it won't "work" it just isn't code compliant.
    Out of curiosity, what do you believe makes the proposed solution not code compliant? I agree that's probably a poor idea as it will confuse people down the road who have to troubleshoot it, but I'm not sure it's actually not allowed.

    As long as both the neutral and phase conductors are switched together, and the switching mechanism is mechanically interlocked (IEC-style reversing contactor, referenced above) it should work.

    I've actually done something similar with an line powered, but battery- & inverter-backed special effect a few years ago.



    SceneryDriver

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    Quote Originally Posted by kwired View Post
    Why not reconnect the thing to 277 for normal power?

    If neutral is common to other 120 volt loads you should be separating that anyway if you want to run at both voltages, not that it won't "work" it just isn't code compliant.
    Yeah, we actually have considered that as well. We'll just need to be sure that we can separate out that circuit. Thanks for the reply.

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    Quote Originally Posted by SceneryDriver View Post
    Out of curiosity, what do you believe makes the proposed solution not code compliant? I agree that's probably a poor idea as it will confuse people down the road who have to troubleshoot it, but I'm not sure it's actually not allowed.

    As long as both the neutral and phase conductors are switched together, and the switching mechanism is mechanically interlocked (IEC-style reversing contactor, referenced above) it should work.

    I've actually done something similar with an line powered, but battery- & inverter-backed special effect a few years ago.



    SceneryDriver
    Was just hoping for a little advice -- it's definitely unusual and weird. We just want to have some viewpoints before making the spec, mostly to be sure that our explanation is understandable. Thanks for the reply.

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    Quote Originally Posted by jumper View Post
    Else, no way I can endorse this solution.
    What code provision does it violate?
    Bob

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