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Taking 1 leg of 120/240v circuit... up to code/safe?

Posted by badmajon (My Page) on
Sat, Mar 12, 11 at 20:03

Hi. I have two welders, one is a standard 240v/22 amp MIG, the other is an odd 120v/26 amp stick/arc welder.

Would it be possible for me to install a dryer style 120/240v 30 amp breaker (the ones with a neutral), and pigtail/split one of the 240v leads and the ground? Then I'd have three hot wires, one neutral and two ground. I'd take the two hots and a ground and put them into the standard 240/30a plug, and the third 240, the neutral and the other ground into the 120/30a plug.

Does that sound like a good idea? Would it be up to code?

The other solution is to simply install two breakers. That's not much harder, but I'd like to simplify if possible given that I won't be operating both welders at the same time.

Follow-Up Postings:

RE: Taking 1 leg of 120/240v circuit... up to code/safe?

The equipment grounding conductor MUST NOT be used as a circuit conductor. Under certain conditions, that can be fatally dangerous. If you add an appropriate neutral, properly installed, the plan is fine.

RE: Taking 1 leg of 120/240v circuit... up to code/safe?

A completely different code section covers welding equipment.

Article 630

Like motor circuits wire size is no longer directly set by breaker size.

RE: Taking 1 leg of 120/240v circuit... up to code/safe?

My basic reading of 630 says that under certain circumstances wire can be undersized based on the duty cycle of the welder. In a residential setting it might be better to run full sized wire to future-proof the circuit recognizing that the next owner might own a different tool and never look at the wire size.

If the MIG welder doesn't require a groundED (neutral) conductor, then you don't need to use a 4-wire receptacle but in this case you would need to pull 3 wire (+ ground) cable or 4 wires in conduit for a neutral required for the 120v stick welder.

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