Max breaker size

fotostatNovember 27, 2009

I have a house with an 8-3 direct burial cable ran from the main panel in the house to the garage. In the main panel it's just looped around and taped up, it still needs to be landed on a breaker. In the garage there is just a coil on the wall waiting for a sub panel to be installed.

For this type of cable, what is the max breaker size I could put in the main panel? 40A? I know there are times that you could get 50A with an 8 gauge conductor, I'm just not sure when.

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Ron Natalie

Depends on what kind of cable it is. If it's UF you're stuck with 40A, if it's USE it's 50A, USE-2 55A. Assuming that it's all copper.

    Bookmark   November 27, 2009 at 8:06PM
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It's just UF :-(

    Bookmark   November 27, 2009 at 9:02PM
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If this is a detached garage it might not pass inspection. I have heard of some inspectors rejecting a sub panel in a detached structure if it is not minimum 60 amp. 8/3 is only good for 40 amp.
I don't think it is a problem if it within the same structure.

    Bookmark   November 28, 2009 at 11:00AM
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It's detached.

The line was already run when I bought the place, I'm not digging it (and the expensive landscaping and cement work) up to replace it with a bigger cable. 40 Amps 240V is PLENTY for my uses.

I'll call up and ask about any minimum size. If there is, then they'll lose out on their permit fee.

    Bookmark   November 28, 2009 at 5:33PM
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The disconnect/panel at the detached structure needs to be at least 60A, but it can be fed from a 40A breaker, so you should have no problem, as long as the wire is 8/3 with ground. You will need a ground rod at the detached structure.

    Bookmark   November 28, 2009 at 5:48PM
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Thanks normel, that'll work!

Another code issue that makes no sense, but at least I'm compliant so there won't be any issue.

    Bookmark   November 28, 2009 at 9:45PM
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If you think you are compliant then you should read this thread.

If you don't get a permit then I hope you don't have any issues when you go to sell the house.

    Bookmark   November 29, 2009 at 11:36AM
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