Workpiece Grounding

[henrym]

It was a theoretical problem.

Aren't all of the grounds in a house or shop electrical system connected? So the ground part of any outlet will have continuity to any other outlet. Wouldn't the two work bench scenario be the same as connecting the work clamp to the ground of one outlet and the welding electrode to another one? If you did that the welding current would flow through the electrical wiring from one outlet to another.

I see what you mean if both benches are just sitting on the ground but not connected to the ground of the electrical system.

Eric

yes, the ground prong in every outlet is connected to the same grounded cable. which is what worries me about clamping a live welding lead to the ground line. and whey I originally thought a separate ground just for the workpiece/table would be a good idea.

Welding current will only travel a vary short distance through earth so if you have earth ground connected to two benches and weld ground to only one there will be no weld current flow from the weld grounded bench to the earth grounded bench ... Note!! a lot of people confuse the common pole in house current is ground. It Is Not. do not connect this to your work piece

but!!! if everything that is grounded is wired together...

fyi. the drawing you posted seems to refer to the ground wire as "common or ground"

the neutral or common wire is the center-taped return wire for 120v household use.

the ground wire is normally not a part of most circuits, and generally provides a safe direct fault path, so the breaker of fuse will go in the event of an electrical insulation failure/equipment damage etc.

[woofer456]

It was a theoretical problem.

Aren't all of the grounds in a house or shop electrical system connected? So the ground part of any outlet will have continuity to any other outlet. Wouldn't the two work bench scenario be the same as connecting the work clamp to the ground of one outlet and the welding electrode to another one? If you did that the welding current would flow through the electrical wiring from one outlet to another.

Eric

Eric
Yes all of the grounds in a house or shop electrical system are connected, and the ground part of any outlet will have continuity to any other outlet......So if you want your work bench grounded to earth and don’t want this to happen. Connect your work bench to earth through a separate grounding rod….
…As a welder one needs to take steps to insure that the object he is welding has a completed welding circuit.
… Another potential problem is laying metal cased power tool on the work bench, as this would be the same as connecting the work bench to the house outlet ground……
…All modern homes have no-fault circuit on all outlets in the garage and outdoor outlets, so if the ground wire is subjected to any sort of electrical current it will trip the breaker for that circuit.

My work bench is grounded through a separate grounding rod to earth. And although the potential for grounding the outlets through a power tools exist, I have (many times) welded with metal cased power tools on the bench and haven't had any problems….
I personally have a grid in the floor of my shop that is welding circuit grounded (with the ground clamp of my welder) and the grid is also connected to my work bench with enough continuity to carry a welding current and if I were to put another work bench in my shop it would also be connected to the grid.
Sorry about the drawing referring as the common as being ground this is not true.
Henerym: if this post covers something you have already posted sorry I (being a poor speller) was composing this post as you posted your last one.
Bob

[matteh99]

I don't think there is a problem with connecting the welder work clamp to the buildings electrical ground as long as the work clamp is on the piece you want to weld. If the work clamp is connected correctly there is no reason for current to flow through the electrical ground circuit.

Of course if the welders input and output aren't isolated then there would also be an issues. But I think most welders are isolated...

Eric

[henrym]

My work bench is grounded through a separate grounding rod to earth. And although the potential for grounding the outlets through a power tools exist, I have (many times) welded with metal cased power tools on the bench and haven't had any problems….
I personally have a grid in the floor of my shop that is welding circuit grounded (with the ground clamp of my welder) and the grid is also connected to my work bench with enough continuity to carry a welding current and if I were to put another work bench in my shop it would also be connected to the grid.
Sorry about the drawing referring as the common as being ground this is not true.
Henerym: if this post covers something you have already posted sorry I (being a poor speller) was composing this post as you posted your last one.
Bob

all is good! more input to this subject is always welcome.

I still see little problem in having a separate ground dedicated to a welding workpiece. honestly can anyone explain why it should be connected to the regular ground circuit? I'd be worried about accidentally starting an arc on any grounded object in the area, with everything being connected to the same ground wire and welding lead...

[JJW]

Great information and commentary. Makes me make sure I'm doing electrical stuff safetly.
Regards,
John

[KHK]

Attached are two drawings that are from;
Miller Welder
Owners manual for Dynasty DX
Nov 1998

One showes incorrect grounding, and the other shows correct grounding.
Notice that this is for HIGH FREQUENCY!! If you are not using HF this extreme grounding is NOT required. I would think that if you are doing both normal and HF, you would ground for HF and leave it alone.

[henrym]

thanks, Keith! looks like my initial guess of 10-12 AWG wire connected to a ground rod near the workpiece was proper. nice to see more good diagrams.

interesting about the "conductive" and "radiative" object difference.

[JJW]

KHK, Thanks for posting the diagrams!

[junes]

i have never done that. All i do is keep all of the electronics away from the welder. By no means keep you ipod or anything like that around it not even your cell phone. Also a radio should be ok. You should only get fuzz at the beginning of the weld when the HF kicks in unless of course your welding aluminum with a transformer machine. Same goes for the tv