Two grounds on the same work piece.

DCEN · Sun Dec 06, 2015 11:42 pm

Hey guys I have a really kind of dumb question, but can you hurt anything if you have the ground clamps from seperate machines on the same workpiece when welding with the other machine. For example I have a Lincoln ac buzz box and a flux cored mig, if I have the grounds to both machines on the work and weld with one of them can i hurt the other machine. Sorry it's such a long post but it's a question that I have wondered about for a while.

exnailpounder · Mon Dec 07, 2015 3:42 pm

Thats a good question. I have left my plasma ground and mig ground on the same fixture and never had anything happen but when I am not in a hurry I disconnect ground of the machine I am not using. I have wondered that myself.

Braehill · Mon Dec 07, 2015 3:56 pm

Our old maintenance shop had a common ground for 6 welders and about 10 different tables so I wouldn't think this should be a problem. These were transformer based machines not inverters, I don't know enough about an inverter's circuitry to say if it's safe with them.

I use the building as my ground in the new shop all the time and have both the plasma and the old transformer welder hooked to it most days. The plasma cutter is inverter based, it's a Thermal Dynamics Cutmaster 52. Never gave it much thought though, maybe it's a bad idea. I'm anxious to hear from the gallery.

Len

ldbtx · Mon Dec 07, 2015 5:11 pm

I can't see where it'd be a problem. It's just one side of the circuit, and it take two sides to make a complete circuit. One shop I worked in, we'd have two machines grounded to the same workpiece and two guys welding on it at the same time. No issues. These were, as in Len's case, transformer machines. My feeling is that it won't hurt inverter machines, but I'm not going to bet somebody else's machine on it. Sometime I'll try it with my inverter TIG and the Miller 252 here at work and report back.

DCEN · Mon Dec 07, 2015 10:10 pm

Wow thanks for such a fast response, and I didn't think it would but figured I'd ask just to be sure. Thanks again.

Poland308 · Mon Dec 07, 2015 10:53 pm

Think most grounds from a machine should be tied internally to your power ground so if you had a bad ground on the machine your using it could ground through the other machine cord. If it happened to be the light gauge ground cord of your plasma it could over heat that cord. It would take a whole series of what ifs but it could happen. I've personally seen chain falls get so hot you couldn't touch them because of a bad ground cable.

rake · Mon Dec 07, 2015 11:07 pm

When I was at the shipyard it was nothing to have grounds from 20 or more machines attached to the same package.
They would also have a ground directly to earth attached to the packages.

Poland308 · Mon Dec 07, 2015 11:09 pm

It took a real fluke acurance and some poorly maintained equipment to cause what I saw.

lsufan15 · Mon Dec 07, 2015 11:47 pm

we also have 8packs all grounded to the same ground and they've been running great for years. I think you will have no trouble.

nickn372 · Tue Dec 08, 2015 3:15 am

A couple little tidbits on this one....

1. Electricity always seeks it's source. It needs to complete it's circuit otherwise it's only potential not current.

2. With welding you are simply completing an electrical circuit. A simple circuit goes from its source through its resistance and back to its source. So unless you hook two welders in series you only have basic circuits being completed.

3. Electricity flows from positive to negative by the path of least resistance. So in order for it to damage another machine the path of least resistance would need to be through the other machine which is highly unlikely. Not unheard of but you may have as good of a chance of lightning hitting the machine.

Any kind of suspect practice in welding can cause damage to people and machinery. Cross your I's and dot your T's and you'll b fine.

ldbtx · Tue Dec 08, 2015 12:43 pm

nickn372 wrote:A couple little tidbits on this one....
...

3. Electricity flows from positive to negative by the path of least resistance.

...

Just a little clarification here. Traditional electrical theory explains a circuit as if the current flows from positive to negative. However, the actual electron flow is from negative to positive.

soutthpaw · Wed Dec 16, 2015 2:38 pm

Yeah, I do it all the time, no problem because nothing is completing a circuit through the second welder.

Sent from mobile. Not responsible for Typos

LtBadd · Wed Dec 16, 2015 8:11 pm

ldbtx wrote:
nickn372 wrote:A couple little tidbits on this one....
...

3. Electricity flows from positive to negative by the path of least resistance.

...
Just a little clarification here. Traditional electrical theory explains a circuit as if the current flows from positive to negative. However, the actual electron flow is from negative to positive.

Damn those pesky electrons!

WerkSpace · Wed Dec 16, 2015 9:24 pm

How fast is electricity? Slower than you might think...

In a direct current circuit, it takes an electron over an hour to pass thru a meter of wire.
In an alternating circuit, the electrons vibrate and will not actually pass thru the wire.