3- or 4-wire to 120v subpanel in unattached "garage"?

dcsullivansApril 22, 2013

Hi -

We have a storage shed about 100' feet from the house on our property. It has no power now, and i'd like to run some out there so that I can have a couple of flood lights, have an outlet for the weed wacker, the occasional portable saw, etc. I only need a 120v circuit at this time.

I plan to run 1 or 1.5" PVC conduit underground with either 3 or 4 THWN lines (neutral, ground, and either 1 or 2 hots.) I'm thinking of using #10 wire, not so much for the amperage capacity, but to limit voltage drop.

Since I only need 120v, I'm planning on leaving the second hot wire (red) capped off at each end. My thinking is that if I ever needed 240v, I'd be able to upgrade without any additional digging, pulling wire, rewiring, etc.

I'm thinking that I'll install a small subpanel in the shed, but connect only 1 side of the bus. The neutral and ground will be isolated from one another, and I'll install 2x 8' grounding rods outside the shed.

Any thoughts or comments on this plan?

In particular, any reason to connect up both hots to the panel right away, even though I only need two somewhat smaller circuits at this time?


This post was edited by dcsullivans on Mon, Apr 22, 13 at 15:05

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any reason to connect up both hots to the panel right away

Why would you not hook up both hots? You'll have done 99.9% of the work already, so why not hook it up?

    Bookmark   April 22, 2013 at 3:59PM
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No real reason, other than I have to have a double-pole ready to go at the main panel.

Things are already a little crowded in there, so I might have to do a little juggling.

    Bookmark   April 22, 2013 at 4:34PM
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The newest NEC requires 4-wire feeds to separate building panels.

What year NEC is the AHJ using

it is NOT always the latest one.

There is a separate provision that allows a single circuit to feed a detached structure without any panel at all.

20 A is the max, and GFCI protection is required on the feed.

A mutliwire circuit is a 'single circuit.'

This post was edited by brickeyee on Mon, Apr 22, 13 at 19:52

    Bookmark   April 22, 2013 at 7:49PM
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2005 NEC.

I'd rather run the 4-wire than do just the single circuit, even though that's probably all I need at the moment.


    Bookmark   April 22, 2013 at 9:26PM
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