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Thread: PNL BUS/BRKR RATING

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    PNL BUS/BRKR RATING

    In what situation would a panelboard have different amperage for the MCB and the bus? Most times I see them the same but do remember them being different once in while? Thanks.

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    Quote Originally Posted by mstrlucky74 View Post
    In what situation would a panelboard have different amperage for the MCB and the bus? Most times I see them the same but do remember them being different once in while? Thanks.
    Some panels have a 200 amp MCB with 225 amp bus. I believe in some cases it is cheaper for a manufacturer to make one bus and use it in multiple panelboards.

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    Quote Originally Posted by packersparky View Post
    Some panels have a 200 amp MCB with 225 amp bus. I believe in some cases it is cheaper for a manufacturer to make one bus and use it in multiple panelboards.
    Actually in all cases. Panel bus sizes are only going to be among a few ratings, different from one mfr to another. 60A, then 100 or 125A, 200/225/ 250A, 400A, 600A, 1200A etc. So if you need a 90A main breaker your panel bus is going to be 100A or 125A, depending on the standard product your selected mfr uses. If you need a 300A main, its going to be a 400A bus, etc.
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    This comes up in solar a lot. I agree manufacturers use the same bus for different main breakers, but the manufacturer rarely will tell you or document this.
    I had some 125 and 250A Siemens factory MLO panelboards and they were exactly the same. I took one of each out of the box and was looking over them and I mixed them up and couldn't tell which was the "125" and which was the "250"

    Edit. Just wanted to be clear that you can factory order whatever you want
    Last edited by electrofelon; 06-13-19 at 11:42 AM.
    Ethan Brush - East West Electric. NY, WA. MA

    "You can't generalize"

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