Any welder guys here?

A little OT, but since PLCs are used on welding machines, not too far off...

We have a dual-head machine that uses plasma arc welders for fusion welding. We are replacing one of these with a TIG welder to handle some more delicate parts and reduce the cost of ownership over the plasma.

My concern - brought to me yesterday by one of the maintenance guys, since I know next to nothing about welding - is that the plasma torch uses a negative ground, and the TIG welder uses a positive ground.

Now, in my experience, when you connect positive to negative, bad things can happen. The maintenance guy says, and I quote, "Yeah, it's called 'welding'".

With all due respect to my good friend of 18 years, I don't want a short-circuit to fry $20k worth of welding equipment, so I thought I'd seek some additional opinions on the wisdom of this.

By the way, the chucks on both welders are separated by 14k ohms of resistance. No idea if that's enough.

Thanks in advance,

TM

There are two big players in welding... Lincoln and Miller, I would contact them

https://www.lincolnelectric.com/en-us/Pages/default.aspx

https://www.millerwelds.com/

I would also contact both, then I would ask the rep that is selling you the rig, I am (was) certified in mig, tig and arc and have been welding since the age of 12 but I have now idea if anything would happen, guessing that if both were not running/arcing at the same time then nothing would happen

EDIT: you may also want to ask here https://forum.millerwelds.com/

No problem.
A welder is simply an electron pump. When electrons flow into the workpiece the energy provides deep penetration, in TIG welding the electrode lasts much longer. Many welding manufactures call the leads "electrode" and "work" instead of "positive" and "Ground". There is an internal transformer that isolates the output (secondary) from everything else.
Advise above was good...call the supplier as you may have some noise issues from the change.

A ground is a ground is a ground, as long as your connections are good. That's the key, having a good ground network. There are companies that specialize in testing/repairing your building's ground network. It might be worth calling them in. Earth grounds deteriorate over time, if you have a lot of welders as we do, it's worth having it tested and/or repaired.