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Thread: Ground bar bonding to breaker box

  1. #1
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    Ground bar bonding to breaker box

    What does code say about the need of bonding the equipment ground bar to the chassis of the breaker box on a sub-panel, that is connected to the main with EMT conduit?

  2. #2
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    NEC says "Where circuit conductors are spliced within a box, or terminated on equipment within or supported by a box, any equipment grounding conductor(s) associated with those circuit conductors shall be connected within the box or to the box with devices suitable for the use ..." 250.148.

    Even better, in case someone feels that a panelboard enclosure isn't a box , is 408.40. "... The terminal bar shall be bonded to the cabinet and panelboard frame, if of metal, ..."

  3. #3
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    Quote Originally Posted by hardworker View Post
    What does code say about the need of bonding the equipment ground bar to the chassis of the breaker box on a sub-panel, that is connected to the main with EMT conduit?
    If this is an equipment ground bar then the screws that are provided with the accessory will suffice to bond the bar to the box. If you are using EMT then there is no need to include an egc-- if that is what you are asking.

  4. #4
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    Quote Originally Posted by Volta View Post
    Even better, in case someone feels that a panelboard enclosure isn't a box , is 408.40. "... The terminal bar shall be bonded to the cabinet and panelboard frame, if of metal, ..."

    We all know that by definition it isn't.

    It's a cabinet.
    Rob

    Chief Moderator

    All responses based on the 2011 NEC unless otherwise noted

  5. #5
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    Quote Originally Posted by infinity View Post
    We all know that by definition it isn't.

    It's a cabinet.
    I don't disagree . . . much :grin:.

    Having some trouble finding that definition of box, though. :confused: .

    I do see where a panelboard shall be mounted in "cabinets, cutout boxes, or enclosures designed for the purpose ..." 408.38.

  6. #6
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    There are two code articles for panels (the incorrect but widely used term)
    312 is the box
    408 is the guts
    Many electricians have only installed loadcenters, which are the box and guts together.
    Moderator-Washington State
    Ancora Imparo

  7. #7
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    If the equipment ground bar is already factory installed in a panel, is it already bonded by the screws they used to factory install it or do you have to add some sort of bonding device to it?

  8. #8
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    Quote Originally Posted by hardworker View Post
    If the equipment ground bar is already factory installed in a panel, is it already bonded by the screws they used to factory install it or do you have to add some sort of bonding device to it?
    Already bonded by the mounting screws, unless it is a special case of an isolated ground bar 250.146(D).

  9. #9
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    Quote Originally Posted by hardworker View Post
    If the equipment ground bar is already factory installed in a panel, is it already bonded by the screws they used to factory install it or do you have to add some sort of bonding device to it?
    Check with the manufacturer. Chances are the bar is already bonded but it's good to be on the safe side.
    Eric Kench, P.E.


    If it's not broken don't fix it

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