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Mains 3-phase wiring question

Discussion in 'Electrical Engineering' started by Mike Cook, Dec 4, 2011.

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  1. Mike Cook

    Mike Cook Guest

    In a print shop, the service entrance equipment has three 125A breakers.
    These feed three 120/208 breaker panels. There is a fourth space in the SE
    panel for another breaker.

    We have need to power one new printing press which draws just under 150A. If
    the total load calculations work out, is there any reason we couldn't use a
    suitable-sized breaker in the SE panel to supply this one load rather than
    install another 120/208 breaker panel?

    Thanks.
     
  2. It depends upon what the SE panel is rated for. Yes the Panels them
    selves have ratings for the bus bars.
    Obviously your running 375A so far. Is it a 400A panel or ....
    If you pop the cover you should see a tag inside as to what the rating
    is. Be careful you got Niagara Falls behind that panel ;)

    Cheers
     
  3. Mike Cook

    Mike Cook Guest

    Why do you think this is an unbalanced load? I have to think a 150a
    It is 3-phase.
     
  4. John S

    John S Guest

    Ask your insurance company.
     
  5. Mike Cook

    Mike Cook Guest

    You didn't say how much current you are being supplied.
    Thanks Tom and others for your comments.

    Yes, we will consult with an electrician or the Utility to avoid any
    assumptions before we do the work.

    Cheers!
     
  6. Mike Cook

    Mike Cook Guest

    Ask your insurance company.

    Insurance is OK with anything within NEC.
     
  7. Gary Walters

    Gary Walters Guest

    IIRC, there was one extra slot available for the circuit breaker. How do
    3-pole breaker.
     
  8. Mike Cook

    Mike Cook Guest

    IIRC, there was one extra slot available for the circuit breaker. How do
    Ah. OK, technically there's 3 slots available. There are only 3-pole breakers
    in this panel so I didn't count individual bus tabs, but 3-pole breaker
    locations.
     
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