3-phase SqD panel

Discussion in 'General Electronics Chat' started by watchman, Aug 21, 2013.

  1. watchman

    Thread Starter New Member

    Aug 21, 2013
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    Will the protection capability of the circuit breakers be degraded in a 480V 3-phase panel, with 480V breakers, if it is installed with a 230V 3-phase feed?
     
  2. radiohead

    Active Member

    May 28, 2009
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    31
    It is recommended to use the proper breakers for the voltage feed.
     
  3. #12

    Expert

    Nov 30, 2010
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    It seems OK from here to use 480 volt breakers on a 230 volt supply. Anybody have any reference material or other evidence that something is wrong with this use?
     
  4. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Breakers operate on current over time, so the voltage should not affect it especially if using lower voltage than the rating.
    Remember any equipment converted over to 230v the current will be proportionately higher.
    Max.
     
  5. #12

    Expert

    Nov 30, 2010
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    I think this is, "Somebody found a free service panel" and they want to know if it will work with 230V 3 phase.
     
  6. GetDeviceInfo

    Senior Member

    Jun 7, 2009
    1,571
    230
    'protection capability' sends me directly to the short circuit rating of the OC device, which is spec'd at rated voltage. If you consider that at short circuit currents, your voltage has likely dropped dramatically. Your panel board/service short circuit rating is that of the lowest rated device. In regards to the trip currents, you need a device that will handle the voltage, so you'll be good.
     
  7. gerty

    AAC Fanatic!

    Aug 30, 2007
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    Will it work? Yes...
    Will it pass inspection? Not here in TN, you must use a panel with the proper voltage rating. Your mileage may vary....

    Edit: You make no mention as to whether it's a Delta or Wye connection, so it may NOT work.
     
    #12 likes this.
  8. watchman

    Thread Starter New Member

    Aug 21, 2013
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    As I understand it, a breaker is a thermally-operated switch. Current over time through a conductor at a given voltage generates a given amount of heat. When that heat reaches the "trip" level the switch operates and opens the circuit. Am I incorrect that a breaker designed to trip at 20A @ 480V will not generate the same amount of heat with 20A @ 230V?
     
  9. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Check one of the breakers, it will most likely show you the voltage range for normal operation, it could well be marked 230-480vac.
    There is no difference in 20amps across a thermal load detection.
    Max.
     
  10. gerty

    AAC Fanatic!

    Aug 30, 2007
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    +1.. 20 amps is 20 amps, across a thermal...
    Is it a 208 WYE service ( you'll need a neutral bar).
    Is it a Delta panel, (has no neutral).
    3 phase panels are marked with their voltage/amp ratings, here in TN they must match the applied voltage to pass inspection.
     
    Last edited: Aug 22, 2013
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