arc welder wiring issue?

[Wisconsintimber]

I have a typical old style 220v 125amp ac Lincoln arc welder. My question is...is there supposed to be voltage on the ground clamp side?  I sometimes get a shock from the work piece when the ground clamp is connected even when I'm not even holding the work(electrode) end, especially if welding outside.  I have also shorted out a trouble light that I sat on my welding table when the ground clamp was clamped to it.  So I tested and I have about 80v going from the ground clamp to the steel on my shed.  Seems alarming to me?  I also have a 250a ideal arc so I plugged that in and got the same results...Do I have a short in the shop wiring?

[Patrick NC]

I am not a licensed electrician but it sounds like a ground problem. Might be a good idea to get a qualified electrician to have a look. 

[mike_belben]

Your shed and your ground clamp need to be at the same potential to prevent shock hazard.  Does the shed service have a properly bonded, dedicated ground?  Does the welder ground line have continuity to the welder chassis and the shed ground circuit?

[YellowHammer]

Yes, you have a potentially very serious problem.  I don't know exactly how your shed is wired, but it sure doesn't sound like it has a local ground rod tied into the electrical panel ground bus as required by code for just this purpose.  Or the shed itself isn't grounded as well.  It's time to open up the electrical panel and see how it is wired, if all the neutrals and grounds are properly tightened, if the bonding grounds are intact, etc and check all the circuits especially the welder circuit.  You may just have a loose lug.  

A ground rod on a welder is exactly that, ground.  There should be near zero voltage when measured to local ground.  You weld with the electrode, not the ground rod.   ;D

I once saw a certified electrician get blown to the ground when he touched a doorknob of a metal building that was otherwise electrically isolated on concrete blocks and had lost its local ground.  The wire to the ground rod had been cut by a lawn mower.  

[Chuck White]

Yes, you have a potentially very serious problem.  I don’t know exactly how your shed is wired, but it sure doesn’t sound like it has a local ground rod tied into the electrical panel ground bus as required by code for just this purpose.  Or the shed itself isn’t grounded as well.  It’s time to open up the electrical panel and see how it is wired, if all the neutrals and grounds are properly tightened, if the bonding grounds are intact, etc and check all the circuits especially the welder circuit.  You may just have a loose lug.  

A ground rod on a welder is exactly that, ground.  There should be near zero voltage when measured to local ground.  You weld with the electrode, not the ground rod.   ;D

I once saw a certified electrician get blown to the ground when he touched a doorknob of a metal building that was otherwise electrically isolated on concrete blocks and had lost its local ground.  The wire to the ground rod had been cut by a lawn mower.  

The first thing I thought of was the grounds, especially the panel BONDING SCREW!
If the bonding screw is not in place, nothing in the shop will be wired correctly!

[Tom King]

Don't use it like that until it gets fixed.  I lost an Uncle to electrocution.

[Don P]

One thing, subpanels do not use the panel bonding screw. The only ground to neutral bond occurs at the initial mains entrance panel. All downstream panels maintain separation of ground and neutral back to that initial panel.

[Wisconsintimber]

Thanks for the replies!  The shop was wired by an electrician and does have a ground rod.  Its about 20 years old and I suspect that it has been an issue the whole time.  I was thinking about the neutral bonded to ground as well...have to look closer or get someone out here to look at it.

The reason I was confused is being ac, the current does alternate and not just go one direction like dc?

[Tom King]

If there are two separate grounds, not connected, all sorts of strange things can happen.

[YellowHammer]

I'm not sure whats going on, but during 30 years of welding, of all types, I've never been shocked to any degree unless I somehow became the ground.  If fact, attaching the ground is basically putting the welding machine on "safe" where it can't get you.

It only takes a few milliamps to kill you, 30 milliamps can stop your heart.  

Being shocked during seeming routine handling of the workpiece or welder is a mystery to me, and would be intolerable.  If you google "Shocked by Welder" there is a lengthy number of injuries and fatal case studies from people getting zapped by their malfunctioning welder.  

I'd call up the manufacturer, it would be interesting to hear what they say.







 

[Iwawoodwork]

Could one leg of the voltage side (120v) have gotten switched with the ground leg if 3 wires, or the neutral leg ?    to those of you who have more electrical skills/knowledge than I , would this cause that type of issue.

[charles mann]

I had a similar issue the other day. Granted gloves and work piece were very damp, but i put my stinger whip on my cutting rig, went to flip the work piece and when i grabbed the mag ground, i felt really good body jolting lil tingle. I went to make sure my bobcat was still grounded, it was, then started walking the leads and found a nick in both the ground and work lead. I had just got the machine out of the shop after getting the carb, voltage reg, fuel pump and fuel shut off solenoid replaced and a good cleaning of the course, fine adjustment and the ac/dc/tig selector. It had nvr shocked me before, even when damp. So i waited till the rain stopped, changed gloves and enviro-tapped the nicks in the leads and didnt have an issue afterwards. Ill check it again next time things are damp and see if the problem exists. 

[mike_belben]

I dont know but i been zapped a few times.  Way back using a tig at a shop i worked in when i was 14, and more recently by a weldernator i built to glue the gate together.  None compare to the 400HZ i got through the chest while unplugging a cannon plug to pack up a radar altimeter test set for deployment.  Your heart can beat that fast and no it doesnt feel good!

[Magicman]

This sounds like either the welder or the receptacle's ground is loose/missing.  It needs to be repaired/fixed.

[btulloh]

This sounds like either the welder or the receptacle's ground is loose/missing.  It needs to be repaired/fixed.

X2 on that.  That's the kind of thing that can happen at times even though the overall wiring, grounding, and bonding scheme is designed correctly.  Usually the simplest explanation is the most likely.  
I ran into this sort of thing with a friends Miller mig rig a while back.  Everything had always been fine, but then this same type of grounding issue came up.  Turned out that the wires in the plug had come loose and the ground connection was missing.  Odd thing and no reason why the terminals in the plug had loosened, but they had.  Fixed the plug, all good.
Moral of the story - check the simple parts first - the plug, the socket it's plugged into, etc.
Dangerous condition as it exists now.

[mike_belben]

Hot and cold does interesting things.  Theres a sheet of plywood on my shed with smooth nails.. They back out a full 2" every year on their own.  

Rural entertainment.   

[Wisconsintimber]

So I looked to make sure and the connections were tight in the panel.  The ground is bonded to neutral so I removed that just for testing purposes and it tested the same...got me thinking, what is the voltage from the electrode to ground...basically nothing!(5v)  I'm thinking that before I got it  someone switched the leads around?  The leads are hardwired into the welder on this one so maybe they switched the ends???  
I need to look more into this and check the grounds at the receptacle...

Also rechecked my other welder and that one seems fine.  Don't remember what I was looking at when I tested that one the first time...