how many split breakers can go in a breaker box??

jaansuNovember 14, 2009

First perhaps a stupid question. I have a 200 amp breaker box but if I add up the breakers, it comes to near 800 amps. Is the thought that while I have 200 amp service, it is unlikely I would ever be drawing full current through even 25 % of them?

A couple of years ago a electrician installed split breakers in about 40% of the slots in my main breaker box to handle extra outlets I wanted throughout the house. We are about to undergo a kitchen remodel that includes a second electric oven but little more power required. The contractor was making noises that he thought a new main box might be needed. It didn't seem that the oven was the problem but that we would have more dedicated circuits needed to bring to current code. So why can't more of the regular breakers be split to get the extra lines? There are still plenty of 15 and 20 amp breakers that could be split. Is there a limit on split breakers to a box?

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I want to say the limit is 42 but that may depend on what version of the code your municipality is using. The manufacturer of the panel will also limit the number of circuits. Check the label for the number.

The combined amperage of the individual breaker will always (or almost always) exceed that of the main breaker. You typically don't use everything at once but there are calculations you or your electrician can perform to see if you have a large enough service.

    Bookmark   November 14, 2009 at 2:39PM
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Ron Natalie

The limit is what the panel supports. It used to be code to limit the maximum OCD's to 42. Some panels accepted less. Some only accept tandems in certain slots to prevent you from exceeding the old 42 limit. It should be marked on the panel somewhere.

    Bookmark   November 14, 2009 at 6:29PM
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The sum of your breakers can be more than the service size, which is ok. Load capacity can only be %80 of the circuit breaker size. The only thing you need to worry about is the actual load. This cannot be more than your service size, which may be what your electrician is talking about. He may think you are getting close to the service size.
Do a load service calculation to determine what the actual load is.

    Bookmark   November 15, 2009 at 1:29AM
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i used to think of it as 10a per pole per amp of main
150 a main 1phase 30 poles max
200 a main ditto 40 poles max
100 a main 20 poles max

    Bookmark   November 16, 2009 at 3:20AM
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"i used to think of it as 10a per pole per amp of main"

No such requirement exists.

    Bookmark   November 16, 2009 at 8:53AM
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