Page 2 of 3 FirstFirst 123 LastLast
Results 11 to 20 of 26

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

  1. #11
    Join Date
    Aug 2004
    Location
    Northern illinois
    Posts
    16,937
    I think this chain of logic precludes doing this.

    700.25 Branch Circuit Emergency Lighting Transfer Switch.
    Emergency lighting loads supplied by branch circuits rated at
    not greater than 20 amperes shall be permitted to be transferred
    from the normal branch circuit to an emergency branch
    circuit using a listed branch circuit emergency lighting transfer
    switch
    . The mechanically held requirement of 700.5(C) shall
    not apply to listed branch circuit emergency lighting transfer
    switches.
    700.2 Definitions.
    Branch Circuit Emergency Lighting Transfer Switch. A device
    connected on the load side of a branch circuit overcurrent
    protective device that transfers only emergency lighting loads
    from the normal supply to an emergency supply.

    Informational Note: See ANSI/UL 1008, Transfer Switch Equipment,
    for information covering branch circuit emergency lighting
    transfer switches
    However, I suspect you could buy a device that is not a whole lot more than a contactor to accomplish the same thing as long as it is listed properly.
    Bob

  2. #12
    Join Date
    Jan 2009
    Location
    3 Hr 2 Min from Winged Horses
    Posts
    15,766
    Quote Originally Posted by petersonra View Post
    What code provision does it violate?
    I did not say it was illegal, I have no clue.

    I said I would not do it unless I had CYA for myself, hence the drawing and stamp.
    "Electricity is really just organized lightning." George Carlin


    Derek

  3. #13
    Join Date
    Dec 2007
    Location
    NE Nebraska
    Posts
    38,252
    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
    Outside of any issues in chapter 7, one would need to transfer the neutral when switching, if the "normal" circuit were a MWBC, you would still have problems with transferring neutral.
    I live for today, I'm just a day behind.

  4. #14
    Join Date
    Dec 2012
    Location
    Placerville, CA, USA
    Posts
    19,653
    Quote Originally Posted by kwired View Post
    Outside of any issues in chapter 7, one would need to transfer the neutral when switching, if the "normal" circuit were a MWBC, you would still have problems with transferring neutral.
    Which is why you can specify and purchase an ATS or MTS with a switched neutral that first interrupts the normal ungrounded conductors, then transfers the neutral, then closes the alternate ungrounded conductors. This keeps you from suffering a voltage divider imbalance during the time the neutral is interrupted. The same sequencing of neutral transfer also happens when transferring back.

  5. #15
    Join Date
    Dec 2007
    Location
    NE Nebraska
    Posts
    38,252
    Quote Originally Posted by GoldDigger View Post
    Which is why you can specify and purchase an ATS or MTS with a switched neutral that first interrupts the normal ungrounded conductors, then transfers the neutral, then closes the alternate ungrounded conductors. This keeps you from suffering a voltage divider imbalance during the time the neutral is interrupted. The same sequencing of neutral transfer also happens when transferring back.
    Now we are getting away from what OP initially wanted to do with just a definite purpose contactor though.
    I live for today, I'm just a day behind.

  6. #16
    Join Date
    Dec 2011
    Location
    Ocala, Florida, USA
    Posts
    2,764
    Quote Originally Posted by kwired View Post
    Now we are getting away from what OP initially wanted to do with just a definite purpose contactor though.

    sort of not, though. If these posts were predicated with No, but you can.... that should make you more comfortable. The simple answer is no you can't use a definite purpose contractor to switch legally required emergency systems, and you can't use legally required emergency power to power lights that aren't part of the legally required emergency systems. I think it is a grey area whether you can power a whole room's lights from the legally required emergency system.

    So, all of those "unrelated" posts are actually potential solutions to the problem the OP presented an illegal solution to.

    that is what I am thinking anyway.


    I know what I don't know, and I know where to go to find it!

  7. #17
    Join Date
    Oct 2018
    Location
    Las Vegas, NV
    Posts
    7
    Quote Originally Posted by Strathead View Post
    sort of not, though. If these posts were predicated with No, but you can.... that should make you more comfortable. The simple answer is no you can't use a definite purpose contractor to switch legally required emergency systems, and you can't use legally required emergency power to power lights that aren't part of the legally required emergency systems. I think it is a grey area whether you can power a whole room's lights from the legally required emergency system.

    So, all of those "unrelated" posts are actually potential solutions to the problem the OP presented an illegal solution to.

    that is what I am thinking anyway.
    Sorry if we're off in the weeds here.

    Our facility uses four-pole (2 NO, 2 NC) Square D definite purpose contactors in every zone for emergency egress lighting. In these zones, normal power and emergency power are the same voltage.

    In every zone, there is a subset of fluorescents that is required to be on for egress. Under normal operating conditions, all fluorescents are switched, so that zones can be dark (we're in a theatre). The egress subset is powered through the two NO poles of the contactor -- when the contactor line-voltage coil is energized (i.e., building power is present), everything is switchable. When the contactor coil loses power (building power is lost), the subset of fluorescents is fed emergency power via the two NC poles, and stays on until power is restored.

  8. #18
    Join Date
    Dec 2011
    Location
    Ocala, Florida, USA
    Posts
    2,764
    Quote Originally Posted by dng View Post
    Sorry if we're off in the weeds here.

    Our facility uses four-pole (2 NO, 2 NC) Square D definite purpose contactors in every zone for emergency egress lighting. In these zones, normal power and emergency power are the same voltage.

    In every zone, there is a subset of fluorescents that is required to be on for egress. Under normal operating conditions, all fluorescents are switched, so that zones can be dark (we're in a theatre). The egress subset is powered through the two NO poles of the contactor -- when the contactor line-voltage coil is energized (i.e., building power is present), everything is switchable. When the contactor coil loses power (building power is lost), the subset of fluorescents is fed emergency power via the two NC poles, and stays on until power is restored.
    Please see post #7 Petersonra gets credit. Use of a definite purpose contactor for this purpose is illegal.


    I know what I don't know, and I know where to go to find it!

  9. #19
    Join Date
    Dec 2011
    Location
    Ocala, Florida, USA
    Posts
    2,764
    Quote Originally Posted by Strathead View Post
    Please see post #7 Petersonra gets credit. Use of a definite purpose contactor for this purpose is illegal.
    Oh, otherwise, using a listed transfer device that is also listed for both voltages would be legal in reference to any of the codes I know. Well, there are little things, like complying with the additional grounding requirements of over 250 volts to ground in the conduit runs.


    I know what I don't know, and I know where to go to find it!

  10. #20
    Join Date
    Dec 2008
    Location
    Oklahoma
    Posts
    658

    Wouldn't be easier to add another light fixture??

    Wouldn't be easier to add another light fixture??

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •