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-   -   Educational Conversation (https://www.askmehelpdesk.com/showthread.php?t=289774)

  • Dec 8, 2008, 11:40 AM
    donf
    Educational Conversation
    Okay, for the purpose of discussion only I would like to continue the discussion from another post regarding the MCB (Main Circuit Breaker) size.

    If you have a 200 Amp service, you should have a Main Service Panel that is listed for 200 amps as well as a 200 Amp MCB, correct?

    You do not want a 100 amp service being protected by a 200 amp MCB because the Main Circuit Breaker would not trip fast enough in the case of a major ground fault, correct?

    A 100 amp service protected by a 200 amp breaker would have to have a ground fault current greater than 200 amps before it would clear the fault, correct? Serious damage could occur to the premises wiring if it was suddenly exposed to a 200+ current running through it. Even worse, suppose the current only climbs to 150 amp, the 200 amp breaker will not react and remove the fault, correct?
  • Dec 8, 2008, 12:41 PM
    ArunRouge

    Yes to all your questions
  • Dec 8, 2008, 05:40 PM
    tkrussell
    A 100 amp service, IE: panel, wire, etc, protected by a 200 Amp breaker is a code violation, and should not be allowed to occur.

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