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  1. #1
    Join Date
    Dec 2007
    Location
    Holladay, UT
    Posts
    577

    Default Service Amperage Rating

    I am a little confused as I have read conflicting statements about this. I inspected a large (8000 sq. ft.) new home. At the exterior service panel were two double pole 200 Amp breakers each connected to its own distribution panel in basement. Is this a 200 or 400 Amp service?

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    Tom Rees / A Closer Look Home Inspection / Salt Lake City, Utah
    http://acloserlookslc.com/

  2. #2
    Join Date
    Mar 2007
    Location
    Fletcher, NC
    Posts
    28,032

    Default Re: Service Amperage Rating

    Quote Originally Posted by Tom Rees View Post
    At the exterior service panel were two double pole 200 Amp breakers each connected to its own distribution panel in basement. Is this a 200 or 400 Amp service?
    Yes.

    It would depend on the size of the service entrance conductors, and it they are sized to 400 amps, then it would be a 400 amp service, however, if they were sized to 300 amps (which is allowed), the the service size is 300 amps. If the service entrance conductors are bus bars, then it would depend on the rating of the bus bars. If either the service entrance or the bus bars are rated over 400 amp, then the limitation would be the 2-200 amp mains, or 400 amps.

    Multiple mains cannot just be added together, however, with a little determination you can usually (but not always) determine what is the limiting factor and the smallest limiting factor would be the service rating.

    Jerry Peck
    Construction/Litigation/Code Consultant - Retired
    www.AskCodeMan.com

  3. #3
    Join Date
    Dec 2007
    Location
    Holladay, UT
    Posts
    577

    Default Re: Service Amperage Rating

    Thanks Jerry. It was what I thought but some people put wrong info in my head.

    Tom Rees / A Closer Look Home Inspection / Salt Lake City, Utah
    http://acloserlookslc.com/

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