Running a 1-phase 240V welder off 3-phase 240V power receptacle?

[Rivets]

If L1 is 120vac to ground and L2 is 120vac to ground, they are 120 degree out of phase, not 180 degrees like standard single phase power.

Not sure what the power supply will think about that.

Maybe you can rent a good (AVR or diesel) generator, or this can be a good excuse to buy one.

Did you look for 110vac outlets in the place like we talked about and tried to trace them to a panel with 220? In commercial buildings, I see 220vac 1PH separate from the 208, 277, 480 all the time.

Hi Mike,

L1 - L2 is only one phase. So is L2 - L3, and L3 - L1.

The 240 volt, 120 degree 3 phase relationship only comes into play when the single phases above are interconnected to a suitable load eg. a 3 phase motor. It has to be that way, because each terminal pair above is connected across a single transformer winding.

So, the 240 volt welder power supply will only see one phase when connected to any one of the above 3 combinations.

Don't know about the "wild" leg.

Cheers,
Rivets