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Thread: Double Breaker

  1. #1
    Join Date
    May 2009
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    Ham Lake, Mn
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    Default Double Breaker

    Is there a limit to the number of double breakers installed in a CB panel (besides rated/maximum amp draw). I am in the process of finishing my basement and am at the wiring phase. I have a 100amp Cutler Hammer panel with 22 poles and 22 spaces (I need to be able to run a total of 29 circuits). Does a double breaker count as two circuits even though it uses a single pole? My aletrnative is to upgrade the panel to a 100amp 30 pole 30 space. I want to get this right before the inspector is scheduled. Any help will be appreciated.

    Thanks.

  2. #2
    Join Date
    Jun 2007
    Location
    Fayette County, Ohio
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    5,836

    Default Re: Double Breaker

    No, you can use as many double breakers as you have the space. The total of the amperage marked on the breakers is of no significance. The individual breakers protect the individual circuits, the main prevents overloading the panel and the service. In other words you could put 300 amps total breakers in a 100 amp panel and it would be OK as long as the total draw at one time does not exceed 100 amps.
    Jack
    Be sure you live your life, because you are a long time dead.-Scottish Proverb

  3. #3
    Join Date
    May 2008
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    Default Re: Double Breaker

    Some panels DO have restrictions on just where in the panel the double breakers can be placed. Look at the panel manufacturer's label, this will tell you what "type" of breakers can be placed in each space.

    The "type" is usually a one or two letter code, and it should also be labeled on the breaker.

    In some cases, you can physically install breakers of a different type than is specified, but you would be stepping outside the ratings of the UL listing and your electrical inspector may not appreciate that.
    The "Senior Member" designation under my name doesn't mean I know a lot, it just means I talk a lot.I've been a DIYer since I was 12 (thanks, Dad!). I have read several books on various home improvement topics. I do not have any current code books I can refer to. I was an apprentice plumber for two years.

  4. #4
    Join Date
    Jan 2008
    Location
    Aurora, IL
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    12

    Default Re: Double Breaker

    I agree with the other answers. Something to keep in mind though: The price of some "piggy-back" or "tandem" breakers has gone through the roof (ahem...Square D QO). If the panel is in an accessible location and you're a pretty handy amateur electrician, It may actually be cheaper to put in a small 60 amp subpanel. I've actually crunched the numbers on a few jobs and it was cheaper to go with a subpanel. I would only suggest it if you're really sure of what you're doing though.

  5. #5
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    May 2008
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    Default Re: Double Breaker

    Just because it's a "200A" panel doesn't mean that you have to limit the total amperage of the branch circuits to less than 200A. For example, if there was enough space and you had the need, it's just fine to install 15 double-pole circuit breakers rated at 20A each -- a total of 300A. Of course, you want to make sure that the normal total load of the panel is less than the rating of the panel or you'll constantly be tripping the main breaker.

    P.S. -- Sorry, JLMcDaniel, I guess I just reiterated what you said.
    Last edited by Fencepost; 05-19-2009 at 10:31 AM.
    The "Senior Member" designation under my name doesn't mean I know a lot, it just means I talk a lot.I've been a DIYer since I was 12 (thanks, Dad!). I have read several books on various home improvement topics. I do not have any current code books I can refer to. I was an apprentice plumber for two years.

  6. #6
    Join Date
    Jan 2009
    Location
    New England
    Posts
    24

    Default Re: Double Breaker

    Remember to label your box. My old box is labeled in such a way I cannot make out what is what. That is going to be my next major project once the kitchen remodel is done.

  7. #7
    Join Date
    May 2009
    Posts
    21

    Default Re: Double Breaker

    this can be a real can of worms. two wire(with ground) circuits are fine. three wire(w/ground) are a whole lot differant. This is a neutral problem. You dont want both legs of a three wire homerun on the same twin breaker. the temptation to use three wire romex is great(2 circuits in one piece of romex) but with twin breakers you can have problems (expensive ones). there is more to it than this but if you are using twin breakers w/3 wire romex you should consult a licensed electrician

  8. #8
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    Default Re: Double Breaker

    Quote Originally Posted by sparky rw View Post
    this can be a real can of worms. two wire(with ground) circuits are fine. three wire(w/ground) are a whole lot differant. This is a neutral problem. You dont want both legs of a three wire homerun on the same twin breaker. the temptation to use three wire romex is great(2 circuits in one piece of romex) but with twin breakers you can have problems (expensive ones). there is more to it than this but if you are using twin breakers w/3 wire romex you should consult a licensed electrician
    What Sparky is trying to say is that if you have two 120V circuits in a single 12/3+G cable, the two circuits need to be on separate poles otherwise you'll overload the neutral. If you put both circuits on the same twin breaker, that will be the case. To avoid this, the two circuits must be on breakers that are connected to separate busbars in the panel.
    The "Senior Member" designation under my name doesn't mean I know a lot, it just means I talk a lot.I've been a DIYer since I was 12 (thanks, Dad!). I have read several books on various home improvement topics. I do not have any current code books I can refer to. I was an apprentice plumber for two years.

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