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Thread: Maximum number of breakers in a switchboard

  1. #1

    Default Maximum number of breakers in a switchboard

    I have been told that if I have more than six breakers or disconnects in a switchboard that I need a main breaker. The switchboard is 575 volts, 2000 amp bus. A main breaker would increase my cost significantly. 230.71 mentions the max number of disconnects but it doesn't say I need a main breaker.

    Can anyone offer me some help?

  2. #2

    Default

    The answer to the question word for word as you asked it is yes and no. Reason for this is conditions you did not mention. If this panel is a main service rated panel in a main structure with no previous overcurrent device aka breaker or fuse then the 6 disconnect rule applies. Each breaker in that panel would be considered as a mian service rated disconnect with 6 being the maximum you can have. The above statement for example would be a panel fed directly from a service company meterbase and not prior fuse or breaker. A second example of this being a yes answer would be if you are feeding a detached accessory structure from a main structure. The fuse or breaker installed in that accessory detached structure where the feeder entered would have a maximum of 6 disconnect rules including the number of breakers in a main lug only panel without a main breaker.

    If the question you asked is concerning a panel that is a slave from a main service rated panel in the same building as that main service rated panel the answer would be no a main would not be required and the 6 disconnect rule would not apply. This is because there is a fuse or breaker in the same building that can be used as the main form of disconnect and this panel being a slave of the main panel would be a subpanel thus not being a main service rated panel. If your panel is a slave of a main service rated panel being a sub panel of that main panel then there would be no limit.

    Even though breakers in a panel are circuit breakers if there is no other means of shutting off that panel then the 6 disconnect rule would apply. Sub panels have a breaker in a panel feeding power to that subpanel that will shut of that entire subpanel then the 6 disconnect rule does not apply.

    They often call the 6 disconnect rule in other words maximum of 6 sweeps of the hand to shut down power coming from that panel.

    Hope this helps

    Wg

  3. #3
    Join Date
    Dec 2003
    Location
    WA
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    4,631

    Default

    Quote Originally Posted by Paul Kluesner View Post
    I have been told that if I have more than six breakers or disconnects in a switchboard that I need a main breaker. The switchboard is 575 volts, 2000 amp bus. A main breaker would increase my cost significantly. 230.71 mentions the max number of disconnects but it doesn't say I need a main breaker.

    Can anyone offer me some help?


    Need more information.

    To add:
    For services, If we look at 230.71(A), you will find that it presents that no more than 6 handles shall disconnect a service from the structure being served.

    Yet, for a detached building--being fed from another. You should look at Part 2 of NEC 225 . (Special attention to 225.36)
    Learning brings success. While you are waiting, I'm getting better!

  4. #4

    Default Thanks

    Thanks for the replies. This switchboard is being fed by five generator strings, the 6th breaker is for a capacitor bank. I hope this is enough information.

  5. #5

    Default

    Now you caused much more confusion and lack of info needed. What do you mean by 5 generator leads. Are you saying you have hooked five generators to five different breakers to feed this panel ? What is the capacitor connection used for ?

    Wg

  6. #6
    Join Date
    Dec 2003
    Location
    Welland Ontario
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    Default

    This sounds way beyond DIY which this site is for. Sounds like you have 6 generators powering a site with a capacitor bank for power factor correction.

  7. #7
    Join Date
    Nov 2008
    Location
    Victoria, BC, Canada
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    Default

    It was way beyond DIY when he mentioned 575 volts and 2000 amps....

  8. #8
    Join Date
    Nov 2004
    Location
    Boston, MA
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    What I can't have 2,000a residential service ?

    I have a big Christmas display !!
    Last edited by scuba_dave; November 25th, 2009 at 11:20 AM.
    DIY Homeowner...not a Pro or licensed electrician

  9. #9
    Join Date
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    WA
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    I agree, if the OP is not a Licensed Electrician (Contractor). Yet, if the OP an electrical professional, then we are here to help.
    Learning brings success. While you are waiting, I'm getting better!

  10. #10
    Join Date
    Jun 2007
    Location
    Central Minnesota
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    Default

    I thought this site was for professionals and DIY'ers alike. Heck we even have a Commercial / industrial section.

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