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Thread: Main 400 Amp Breaker

  1. #1
    Join Date
    Apr 2017
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    texas
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    Main 400 Amp Breaker

    Is it okay to install a 400amp main when the Servie transocket is 200amp?

  2. #2
    Join Date
    Dec 2012
    Location
    Placerville, CA, USA
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    17,477
    What is a Servie transocket?

    In general POCO will not like to see a service disconnect with OCPD greater than their designation of the service size. Even though the actual calculated or connected load may be smaller than that.

  3. #3
    Join Date
    Apr 2017
    Location
    texas
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    Yes, i was thinking that.
    Its a temporary service and want to use the existing panels on site. The main is a 400 amp feeding a 100 amp breaker and another 70 amp.

  4. #4
    Join Date
    Dec 2007
    Location
    NE Nebraska
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    32,120
    Quote Originally Posted by GoldDigger View Post
    What is a Servie transocket?

    In general POCO will not like to see a service disconnect with OCPD greater than their designation of the service size. Even though the actual calculated or connected load may be smaller than that.
    Maybe. Some only care about the load. Some still even have transformers that are a little undersized compared to what we would have to install.

    Not so long ago I installed a 208/120 service with a 1200 amp main. POCO selected their equipment and rate schedule based on load not the service disconnect. Actual load was less then 600 amps, and they supplied it with a 225 KVA transformer. Should load ever increase enough they need different equipment they will adjust accordingly. Demand charges may kick in before that happens and prompt customer to initiate communications to the POCO about usage.

    Also recall another similar situation - 208/120 again, 6 mains that if you add them together totaled 1050 amps, was only supplied with about 750 amps of service conductor ampacity, actual load probably less then 300 amps, capacity to handle a future chiller was built into the install though. Still was supplied with a 150 kVA transformer, maybe even only a 112.5.

  5. #5
    Join Date
    Oct 2009
    Location
    Austin, TX, USA
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    Quote Originally Posted by Chris Lloyd View Post
    Is it okay to install a 400amp main when the Servi[c]e transocket is 200amp?
    If it is fused I would put 200A fuses in it.

  6. #6
    Join Date
    Nov 2003
    Location
    Roanoke, VA.
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    3,988
    Quote Originally Posted by ggunn View Post
    If it is fused I would put 200A fuses in it.
    He would need fuse reducers (adapters)
    200 amp fuse is too small to fit in 400 amp disconnect.
    Sometimes I don't know whether I'm the boxer or the bag.

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