Installation of Bury Cable

Old 12-06-07, 02:01 PM
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Installation of Bury Cable

I have a 10 x 14 shed about 100 feet from the house. I had a 50 amp sub panel installed in the electrical room of the house, so I have capacity. I think I only need 20a, single circuit in shed (single inside and outside light, single duplex recepticle inside).

What size of bury cable should I use and at what depth? Also the best method to install bury cable? I'm assuming some sort of rental trencher.

Old 12-06-07, 02:18 PM
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Depends on how confident you are about only needing a single circuit, both now and into the future.

Also depends on how much of that 20 amps you might typically be using, and for what kind of equipment.

If you are confident about the single circuit, and if you'll almost never be using the full 20 amps, and if you don't have any large motor loads, then just run 12/2 UF-B, protected by a GFCI receptacle before it leaves the house, buried at least 12 inches deep, and sleeved in PVC conduit while above ground and to the bottom of the trench. Use a simple light switch as a master shutoff just inside the shed.

There are many other options if my "if" statements above are not true. Give us more details if you want to know more.
Old 12-06-07, 04:43 PM
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I thought it was 18" for nonconduit cable (UF) and 12" for THWN in conduit?
Old 12-06-07, 05:01 PM
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GFCI changes those numbers.
Old 12-06-07, 05:09 PM
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Go here and look at article 300 (table 300.5 column 4) and you will see to what John is referring. You need to click agree then click open the nec then click the index icon after the big red page appears.
Old 12-06-07, 07:49 PM
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Recommend you bury 12/3 wire. The cost is minimally more, and if you ever want to use more than 20A, you'll have it there ready to go without having to re-trench.

Now's also a good time consider an extra conduit for a telephone, remote speakers, intercom, network, etc.

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