12/2 vs 12/3

Old 11-01-04, 01:28 PM
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12/2 vs 12/3

Hi all.

I'm trying to add more outlets to my garage - even though the house is less than 10 years old, there's still only one outlet in the garage and that's not particularly well-placed.

My plan is for three more 110v outlets on the easily accessible wall - on the far side of the garage from the breakers. I was thinking that 20a should be sufficient. I was thinking to pull the wire myself before getting an electrician out to install the GFCI breaker and connect the wires to the box, my time is cheap and theirs is not.

I went to the store to pick up a roll of wire. I bought a huge roll of 12/2, but they also had 12/3... since 12/2 has two conductors plus the ground, is there any reason I'd need to run 12/3 for 110? I figured that it'd be a good plan to ask before I opened the spool in case I needed to return it and get the other.

What about later when I add 220 for an air compressor - that'd be like 12/3 or 10/3 needed for 220, depending on amp rating of the compressor, right?

Thanks for any advice.
Old 11-01-04, 01:50 PM
Join Date: Sep 2000
Location: United States
Posts: 17,733
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You bought the right stuff. 12/2 will be all you need for receptacles and lighting. Even for your 240-volt compressor, all you'll need is X/2, where X depends on amps.

You need 12/3 only if you plan any 3-way switches.

Don't run this cable on the surface. It needs some form of physical protection.

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