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Thread: Sub panel

  1. #1

    Default Sub panel

    I would like to install a subpanel to supply power to a pool house, I have a total of 10 circuits, listed as follows.

    3 20 amp to support gfi over bar and bath sink
    1 20amp for refer
    1 20amp to support 14' of 220v electric hydronic baseboard heater
    1 20amp to support 12' of 220v electric hydronic baseboard heater
    1 20 amp to support electric hot water heater
    3 15 amp to for lights and outlets

    The sub panel will be located 40' from the main panel. I have 3 questions. What gauge wire should I use, What amp breaker should i use, and should i put a breaker in the subpanel as well as the main.
    Last edited by gf2@inbox.com; 12-22-2008 at 04:18 PM.

  2. #2
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    Default Re: Sub panel

    please talk to an electrician and don't rely on posts from unknown posters.

    there are some on this website that know their stuff on electrical. but there are certain ones who post on every subject and only do google research. it becomes obvious rather quickly. just double check all information.
    Last edited by havanagranite; 12-22-2008 at 07:13 PM.

  3. #3
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    Default Re: Sub panel

    gf2,

    Is the "pool house" attached to the house structure or is it a free standing auxiliary structure?


    Quote Originally Posted by havanagranite View Post
    please talk to an electrician and don't rely on posts from unknown posters.
    Yes by all means do not use information or opinions from this forum as a substitute for advice from a licensed qualified professional, because this is a Home owner forum and everyone who posts here are unknown and despite whatever claims they or any other poster may make, are not anything but that. Check out anything for yourself.

  4. #4

    Default Re: Sub panel

    It is seperate and it is about a 70 foot run

  5. #5
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    Default Re: Sub panel

    I don't want to take anything away from the comments of other posters. The advice of an electrician or expert is far better than the speculations of an anonymous person. However, as long as you take what I say with the proper grain of salt, here are my thoughts. I have some experience and training, but I'm NOT an electrician.

    The wire size for each of the circuits you described will most likely be dictated by the rating of the breaker. Thus, the 15 amp circuits will be protected by 15 amp breakers and use #14AWG or larger copper wire, and the 20 amp circuits will be protected with 20 amp breakers and use #12AWG or larger copper wire.

    It is not required that the total amperage of the sub-panel be equal or greater than the sum of the circuit breaker ratings. In other words, even though the sum of all of your circuits is 185 amps, you won't need a sub-panel rated for 185 amps or more. You could use a 100A or smaller panel.

    The breaker panel you buy to use as the sub-panel will probably come with a master breaker in it, If not, I'd recommend you put a main breaker in the sub-panel that can shut all the circuits off with a single flip of the switch. Since the sub-panel is 40 feet from the main panel, you must also have a breaker in the main panel protecting the sub-panel circuit.

    For the main-panel to sub-panel circuit, you need to use a wire guage sufficient to carry the rated amperage of the breaker protecting it. That means the breaker in the main-panel. Also, the circuit must be dedicated to the sub-panel... no splitting off to feed the HVAC or some odd device.


    Let's pretend you purchased a 100A breaker panel to use as the sub-panel. You could put a 50A, 60A, or even 100A 240V breaker in the main panel. The rating of the breaker in the main-panel (the one protecting the circuit to the pool house) does NOT have to match the main-breaker in the sub-panel itself, but it will probably cause less stress on the next guy that owns your home if it did.

    The ampacity of the wires from the main-panel to the sub-panel must be capable of carrying more than the rating of the 50A, 60A, or 100A breaker you put in the main-panel. Undersized wires protected by oversized breakers can heat up and cause a fire before the breaker flips. Oversizing the wire will not cause any harm.

    You will need 4 wires running from the main-panel to the sub-panel. Two for the two 120 volt legs, a neutral, and a ground. If the wire you buy isn't color coded, use black and red for the two hot legs, white for the neutral, and green for the ground

    Finally, the neutral can contact the ground only in the main-panel. This is usually done through the metal panel box itself, with copper or aluminum screws. But in the sub-panel, the neutral must be isolated from the ground.

  6. #6
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    Default Re: Sub panel

    Because it's a separate building I would recommend it have a main so you don't have to run to the house to turn the power off.
    I would suggest a 100 amp sub with a 100 amp breaker in the main panel.
    You should use #2 copper or #1 aluminum 3 conductor plus ground.
    Jack
    Be sure you live your life, because you are a long time dead.-Scottish Proverb

  7. #7
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    Default Re: Sub panel

    Quote Originally Posted by JLMCDANIEL View Post
    Because it's a separate building I would recommend it have a main so you don't have to run to the house to turn the power off.
    I would suggest a 100 amp sub with a 100 amp breaker in the main panel.
    You should use #2 copper or #1 aluminum 3 conductor plus ground.
    Jack
    In Pa that would be allowed as long as the main load center is rated for 200 amps.
    I did not see mention of that, as we both would agree that is paramount.

  8. #8
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    Default Re: Sub panel

    Quote Originally Posted by Ernie_Fergler View Post
    In Pa that would be allowed as long as the main load center is rated for 200 amps.
    I did not see mention of that, as we both would agree that is paramount.
    Excellent point Ernie. I'm a little embarrassed I don't catch that.
    Jack
    Be sure you live your life, because you are a long time dead.-Scottish Proverb

  9. #9
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    Default Re: Sub panel

    Quote Originally Posted by JLMCDANIEL View Post
    Excellent point Ernie. I'm a little embarrassed I don't catch that.
    Jack
    I had to Google it myself.....
    Great minds Google alike.

  10. #10
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    Red face Re: Sub panel

    If you are feeding a separate building, you will need a separate grounding electrode system as well as other requirements specific to pool equipment. Use an electrician. Water and electricity can be a deadly combination. (Yes, I am an electrician, but I work for the local utility company, so I don't have any out of work buddies that I'm trying to find work for).
    Just because you can, it doesn't mean you should!

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