Combining Mig Welder and Plasma Cutter Grounds

Industrial Toys · Nov 22, 2016

Thanks for that. Just called them. INTERESTING!

The cutting lead is actually positive! The torch is negative.

So they do not recommend combining grounds, especially if both machines COULD be used at the same time.

He asked what the welder polarity was, and I don't know. I am guessing, that is a floating ground as well. Otherwise, if you were welding on something that was electrically grounded and lost your ground clamp, the welding currents would go through your (skinny) electrical system ground with predictable results.

CNC Dan · Nov 22, 2016

forgot to quote. re-posted below.

CNC Dan · Nov 22, 2016

ovrszd said:
Yep, you cleared my stupidity. I have no idea if his proposition will work. Thanks for your patience and politeness.

This is why most machine owner's manuals now call it a 'work' clamp and not a 'ground' clamp.
And the output of most(all?) modern welders is isolated from the input power/neutral/ground.

But I think on some older welders, that may not be true. And if the transformer insulation has broken down, you may have some connection from the welders output to chassis ground.

ENC · Nov 24, 2016

I know on my big box store model Lincoln might machine that I have to reverse the polarity by switching which lug the cables are screwed to when switching from Flux core to shield gas wire.

dickfoster · Nov 25, 2016

Industrial Toys said:
Thanks for that. Just called them. INTERESTING!

The cutting lead is actually positive! The torch is negative.

So they do not recommend combining grounds, especially if both machines COULD be used at the same time.

He asked what the welder polarity was, and I don't know. I am guessing, that is a floating ground as well. Otherwise, if you were welding on something that was electrically grounded and lost your ground clamp, the welding currents would go through your (skinny) electrical system ground with predictable results.

MIG welder polarity varies.