Hi, first post here & I would really appreciate some input from any electrical experts.

We gave our son an MM180 for Christmas and later learned that the 220 outlet in his studio (he's a sculptor) is not live. The building is totally rewired--except for that circuit.

The MM180 specs are:

Input Power
230 V, 21.7 A, 60 Hz
Rated Output
135 A at 22.5 VDC, 30% Duty Cycle
Welding Amperage Range
30 - 180 Amps

In reading here and on other forums, I think I have two options.

  1. extend a 220 circuit that is almost never used another 100 feet to his studio. This is a 4-wire, 120/240-volt circuit, so if I understand correctly, I would have to cap the neutral on either end and make sure the ground is connected correctly. this circuit is fed by a double 30-amp breaker, 10-gauge wire, and is currently about 60 feet long. I would be adding 90 to 100 feet of 10 gauge to it. Does all this sound right? Can I use the two hots coming from the double 30-amp breaker?
  2. run a totally new, dedicated circuit of 10-2 plus ground, in conduit, about 150 feet from panel to receptacle. If I do this, there are only two empty slots in the breaker panel and they are opposite to one another. would I take the hot wires off of two single, 30-amp breakers in this case?

I've done a fair amount of 110-v wiring in my time; not that much 220. I just want this to be safe and done right.