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Thread: Basic electric service panel questions

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    DIY Member JMingrone's Avatar
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    Default Basic electric service panel questions

    I'm having a home inspection this weekend on the house I'm selling and I'm a little concerned about the electrical inspection.

    A couple quick questions:
    1) For a 200 amp service, you draw 200 amps from each leg, right?
    2) Is it a problem (does code require) that the breakers on each leg total to less than 200? Or is it only necessary that the actual load being drawn be less than 200 amps? I have a total of 230 amps of breakers on one leg and 200 on the other.

    Will this be a problem?

    Thanks

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    DIY Senior Member Murphy625's Avatar
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    Yes.. 200 max on each leg.
    No. Breakers can total far more than the mains. The mains are protected by their own breaker. It is assumed that you will never draw the maximum current on every breaker simultaneously. If you did, the main breaker on a mains panel, or the feeder circuit breaker on a main lug panel would trip.

    Always remember, breakers are not there to protect the devices. Breakers are only meant to protect the wires.

    Hope that helps,

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    DIY Member JMingrone's Avatar
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    Great, thanks!

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    Retired Defense Industry Engineer jadnashua's Avatar
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    It might be an issue if the panel was full of breakers and you had lots of heavy use appliances in the home, other than that, not a problem. For example, say you had multiple, big water heaters, big a/c units, a pool heater, a commercial style 8-pot stove and multiple ovens...then 200A may not be adequate. This isn't an issue for the vast majority of people...
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    Moderator & Master Plumber hj's Avatar
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    It could also be a problem if you had ALL the high draw 120v items, such as microwave, space heaters, blow dryers, etc., all on the same leg of the feed and they all operated simultaneously at the same time as the major 240v ones, such as A/C units, water heaters, pump, and oven, which although unlikely could happen at some time.
    Last edited by hj; 07-18-2013 at 07:22 AM.
    Licensed residential and commercial plumber

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    Jack of all trades DonL's Avatar
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    Quote Originally Posted by hj View Post
    It could also be a problem if you had ALL the high draw 120v items, such as microwave, space heaters, blow dryers, etc., all on the same leg of the feed and they all operated simultaneously at the same time as the major 240v ones, such as A/C units, water heaters, pump, and oven, which although unlikely could happen at some time.

    That is Exactly how a lot of Inspectors Test here, when you are buying a house.

    But they are the Good ones, and you pay well for a good inspection.


    Good Luck.
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    DIY Senior Member Murphy625's Avatar
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    Quote Originally Posted by hj View Post
    It could also be a problem if you had ALL the high draw 120v items, such as microwave, space heaters, blow dryers, etc., all on the same leg of the feed and they all operated simultaneously at the same time as the major 240v ones, such as A/C units, water heaters, pump, and oven, which although unlikely could happen at some time.
    Ok.. I'll bite..
    The way I'm reading your reply, it seems that you're implying that drawing too many amps on one leg is somehow more detrimental than drawing too many amps equally on both legs.

    What difference does it make?

    And for the sake of this discussion, lets leave out the theoretical voltage drop issues.

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