220 service using 12 gauge wire

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Old 06-04-13, 01:13 AM
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220 service using 12 gauge wire

Hi juice pros. My little brother wants to get a mig welder and set up shop in my garage for his new business venture. I now know they have welders that can operate on 120v circuits but he was asking if it would be possible to get 220 service in there in case he needs a bigger welder.
Many years ago I installed underground UF 12 gauge which was then barely fed through rigid pipe approx 25-30 feet from house to garage. I then had electrician connect that wire to house panel and in the garage he put in a breaker panel and wired the outlets and overhead lights.

Is it possible to put 220 service in the garage with this set up? I don't want to dig a trench again to install another line. Thanks!
 
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Old 06-04-13, 02:25 AM
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Welcome to the forums! 12 gauge wire will only carry 20 amps, tops. You probably have only 120 volt service at this time. What size breaker did he hook the wires to in your house panel? Unless you can run larger (#6 or so) THWN wires through the conduit and remove the 12-2 UF, I'd say it was trench digging time again.
 
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Old 06-04-13, 06:17 AM
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Thx for the welcome..

....or welcome back. I used to get advice and info a long time ago on here. Your answer is what I thought I would get. I wish I put in a larger line at the time. The fuse is 15A in the house. I never tried screwing in a 20A fuse but I guess I might as well since the wire is 12 gauge going out to the garage. This 'garage fuse" is not connected to anything but the line to the garage. I'm not sure though a 20A would even fit in the socket. Maybe I'll just use a penny. KIDDING
 
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Old 06-04-13, 06:30 AM
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With just two #12 wires (not counting the bare ground wire) you have a choice of 20 amps at 240 volts only or 20 amps at 120 volts only.
 
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Old 06-04-13, 06:34 AM
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Welcome back.

First off your house has 240 not 220. A common misunderstanding.
Second you can't have two sources of power to a detached building so to have both 240 volts and 120 volts you must abandon the current 120 volts and install a subpanel.

Just a heads up. Best practice is to not run UF in conduit. No need except for short lengths to protect it above ground and it can be a bugger to pull.

The fuse box poses the greatest challenge to running the necessary power. Unless you have an unused pull-out for cartridge fuses the largest service you can run with Edison based fuses is 30 amp and you will need two Edison fuses to even run a 240. It may be time to talk about upgrading to a breaker panel.
 
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Old 06-04-13, 01:14 PM
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he was asking if it would be possible to get 220 service in there in case he needs a bigger welder.
Many years ago I installed underground UF 12 gauge which was then barely fed through rigid pipe approx 25-30 feet from house to garage.
220V, no. 240V, yes.

What size is the conduit? If it's large enough, you may be able to use the Type UF to pull a pull string through the pipe, and use that to pull new THHN/THWN wires in. Of course, doing that won't resolve any problems with your existing panel.

What would the amp draw of the new welder be?
 
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