220 v for sub-panel

avirex7823g1March 6, 2010

Registration here comes under the "difficulty file."

Now back to the reason for the post. I have a main panel in the two car garage, and I have a sub panel in the detached garage. I have #6 gauge 2 wires...Red, Black, White, and Green connected to a two pole 50 amp circuit breaker in the main panel. The #6 four wires run in a 1-1/2" gray PVC pipe ...2 feet under ground to the sub panel. There are six slots for circuit breakers. I have four 20 amp single breakers with 110 v to all the receptacles I need in the garage. I need to install a 220v receptacle for my 220 volt welder. Question. Do I need to install a 50 amp two pole breaker? As on the other end in the main panel there is the 50 amp two pole that feeds the sub panel. What size wire will I need to feed the wall receptacle? The plug on the welder in a three prong. Do I need to run two Blacks and White to the wall receptacle, or four wires? Also, will I need to make the main panel two pole circuit breaker a 100 amp?

Thanks for the great replies.

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Ron Natalie

If you have six or fewer circuit breakers in the same panel you can get by without a disconnect. Normally, I'd say put one in anyhow but if the panel is so small to preclude ever getting over 6 circuits anyway, there's no point.

Welders are a special part of the electrical code, and you've not given us enough information as to how to size the conductors or the breaker. Usually the easiest way to determine this is to look at the manufacturers recommendation in the manual. If the plug for the welder only has three prongs then you run three wire (two hots for the 240V and a ground). If it's 240, the color WHITE should not be used. It should be some color other than white, gray or green.

You can not protect #6 with a 100A breaker. If you need more amps (which I'm not sure you do), you'll need to run larger feeder wires.

    Bookmark   March 7, 2010 at 8:22AM
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ronnatalie, Thanks for the reply.
Here's what the manual states.
INPUT: 230v. 60 HZ, 22.5A, 1 Phase.
OUTPUT: 120A @20VDC. 25%. MAX O.C.V=30VDC. Max 150A

I'm thinking of using 10AWG wire from the sub panel to the wall receptacle with a 60 amp breaker. I will have to go back to the main panel and change the 2 pole breaker to 60 amp, as it now has a 50 amp breaker supplying the sub panel.

Would this be appropriate to use?

    Bookmark   March 7, 2010 at 9:25AM
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Ron Natalie

The 10AWG and 60A breaker would be fine for this welder (I assume this is some sort of arc / tig /mig).

You wouldn't need to upgrade the feeder breaker, though with #6 COPPER conductors you could if you wanted to.

    Bookmark   March 7, 2010 at 11:33AM
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