I need to wire for a MIG welder (Miller 211). Manual recommends max. 25 A circuit breaker with trip curve comparable to time delay fuse and min. 14 gauge wire per NEC Table 310.16. I'm thinking I would like at least one but perhaps two 120V 20A outlets for light, grinder, etc. Initially, I thought I could run 14/4 and put an outlet on each leg, but then got to thinking what would happen in the event one of the 120V devices faulted but not enough to trip the breaker. This setup would also asymmetrically load the two legs when using both the welder and a tool, although that isn't very likely and could trip the breaker.

So, the questions that come to mind:
1. What is correct way to wire this?
2. 14 gauge seems light?

I am not seeing what you mention for specs in the datasheet:

http://www.millerwelds.com/pdf/spec_sheets/DC12-54.pdf

If your manual states #14 wire, then go for it, but I would run #12.

If you run 4 wire cable, that would be two circuits, each with a separate neutral?

You do mention "run 14/4 and put an outlet on each leg", so you plan on using a shared neutral?

I would not recommend that either.

Circuits using shared neutral should be protected ith the same size rating circuit breaker.

Has this helped? If not can you elaborate?

I am not seeing what you mention for specs in the datasheet:

The wiring info is in the manual (http://www.millerwelds.com/om/o239988e_mil.pdf) on page 18.


If not can you elaborate?

I was thinking out loud if two 120V outlets could be pulled off a single 240V circuit and have everything work properly in the event of a fault, and what I was thinking seemed to run into a logical dead end for having the 120Vs protected properly. So, is running a 240V circuit and two separate 120V circuits each with appropriately sized breakers the proper way to do this? If so, is there a single armored cable for doing it in one run or is conduit with individual conductors the way to go?

OK now I see your unit is 240 volts. The unit will need a separate dedicated circuit.

Since the unit needs a 25 amp breaker, you cannot use the circuit or breaker for 20 amp devices.

There is 4 wire romex or even MC cable available, MC cable has 6 and 8 wire cable available.

Of course, conduit will allow multiple circuits, but cable is available as I mention.

I would be running #12 wire for the welder, and two wires, hot and neutral for each 120 volt circuit.

I would be running #12 wire for the welder, and two wires, hot and neutral for each 120 volt circuit.

Then that's what I'll be running unless the inspector has his own ideas. Thanks.

Is this a garage location or would the installation benefit by installing, say a 60 A sub-panel?

I haven't decided where it's going yet. Eventually it will be in a separate workshop fed with it's own service so this is "temporary". I may run exterior outlets and drag everything outside.