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    bigdoe's Avatar
    bigdoe Posts: 1, Reputation: 1
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    #1

    Aug 24, 2010, 06:38 PM
    Can I put a 150 amp breaker in a 200 amp panel to feed a 150 amp sub panel?
    Can I put a 150 amp breaker in a 200 amp panel to feed a 150 amp sub panel with a 200 amp service?
    KISS's Avatar
    KISS Posts: 12,510, Reputation: 839
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    #2

    Aug 24, 2010, 08:19 PM

    Not likely because the max breaker size for the panel will probably be limited to 100 or 125 A.
    donf's Avatar
    donf Posts: 5,679, Reputation: 582
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    #3

    Aug 25, 2010, 11:52 AM

    Okay,

    Let's think about this for a moment.

    You have a 200 Amp service to your home. You want to divert 150 amps of the 200 amps to service a sub-panel?

    Do you realize that your main service would starve while the sub-panel is in use?

    Might I suggest this, properly size the load that the sub-panel needs and then determine the size of the breaker and sub-panelboard needed for the sub-panel.

    Breakers are normally only sized to an 80% load for example, [edited] a 100 amp breaker will normally carry only 80 amps.

    Most garages, that I have seen, use only about 60 Amps which is enough to run some tools, power strips and lights. I have no doubts that there are larger panels and feeders in use, I have never worked on any.

    You really need to give us much more information regarding the calculated loads for both the main service panel and the calculated load for sub-panel before we can provide accurate information to you.
    tkrussell's Avatar
    tkrussell Posts: 9,655, Reputation: 724
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    #4

    Aug 25, 2010, 01:15 PM
    Don, Bigdoe asked a simple question, Kiss provided the simple correct answer.

    Why all the assumptions?

    Bigdoe never stated it was for a home, or garage, or anything.

    Many times homeowners get a 200 amp panelboard at a service location, and they don't want to run all the branch circuits to that panel, but want a load center closer to the branch circuits.


    See now you got me making assumptions.

    Simply answer the questions. In this case it was done.


    And, can you explain this statement you made:

    Breakers are normally only sized to an 80% load for example, will normally carry only 80 amps.
    donf's Avatar
    donf Posts: 5,679, Reputation: 582
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    #5

    Aug 25, 2010, 06:29 PM

    Okay, TK,

    I was not making assumptions, I was using examples for why more information was needed. [edited] The question could have been answered simply by saying, "Look at the panel Spec Sheet to get the largest "Circuit" breaker listed for the panel" and the poster toddles off and puts a 125 amp breaker in to feed a 125 A sub panel to power a 5 bay garage with car lifts, compressors, A/C, Heat ect. How many times have you told me not to assume the poster knows what they are doing, ask them? [edited]

    Your case in point, without knowing what the poster is trying to do makes an exact answer difficult.

    As to the statement you questioned, there was text missing. The full line should have read, ".. a 100 amp breaker will normally only carry 80 amps."
    donf's Avatar
    donf Posts: 5,679, Reputation: 582
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    #6

    Aug 27, 2010, 12:16 PM

    Just as an aside, I went through some Square D panels and turned up some 200 A panels will allow a "Branch Circuit" breaker up to 200 amps. It is a double throw, 4 pole breaker.

    The Panelboard - is P/N QO13040L200G.

    So, the correct answer is yes, if the panel specifications allow it.
    tkrussell's Avatar
    tkrussell Posts: 9,655, Reputation: 724
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    #7

    Aug 27, 2010, 12:46 PM
    Don... Don... Don, what am I going to do with you?

    http://ecatalog.squared.com/pubs/Ele...0110PL9401.pdf


    Gotcha. Well done, that answered the question. And I sure learned something about the product.

    And as I reflect, I see what you were, I think, try to warn big doe about, just a different approach.

    Using a 200 Amp breaker in a 200 Amp panel really needs wise, and even perhaps, professional advice, and take close look at the application. This 200 Amp breaker should only be used in special cases.

    Any use of this breaker requires accurate load calculations to be done on the panel, and upstream of the panel.

    I can appreciate the effort in what you found, Square D Digest is not the easiest catalog to navigate, to be polite. Believe me, I am not this polite when I speak with Sq D reps.

    I included the available datasheet for the product as back up of your find.
    KISS's Avatar
    KISS Posts: 12,510, Reputation: 839
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    #8

    Aug 27, 2010, 10:08 PM

    At least I'm off the hook too:

    Quote Originally Posted by KISS
    Not likely because the max breaker size for the panel will probably be limited to 100 or 125 A.
    Does allow the possibility of donf's answer. You know the old saying: "Never say "Never".

    Nice work don.

    So, did you get that panel replaced yet?
    tkrussell's Avatar
    tkrussell Posts: 9,655, Reputation: 724
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    #9

    Aug 28, 2010, 03:17 AM
    I agree Kiss, until Don found this QO 150 and 200 Amp branch circuit breaker, my knowledge was that the maximum branch breaker allowed by all brands of panels was either 100 or 125 amp.

    Since I don't do much residential, I don't have much reason to read everything available on the QO brand.

    If I needed a 200 amp feeder, I certainly would not consider installing a 150 or 200 amp branch circuit off a 200 amp panelboard.

    Honestly, I wish Don did not find it, can give some DIY'er the wrong idea. Lord knows they come up with enough on their own.

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