Welder Grounding

[Eng]

I have a client that would like a grounding bar installed in their welding bar so that they can clamp their welder ground to it. Is this a common item? I was always under the impression that while welding you ground to the equipment that you are welding. They have requested a ground bar with a grounding conductor connected to a ground rod.

Any issues/concerns with this?

 

[socalelect]

they want to earth ground the welder's secondary connection ?
andyes when welding grounding (connecting the work lead) as close as possible to where you are working is best due to EMF among a host of other things
if they in fact want to earth the welders secondary
this would probably cause problems due to the change in polarity that the welder makes and most are DC as well if its tig it could also be a high freq current as well

in the welding world the ground clamp is the work lead and the one the welder actually holds is called the electrode cable or gun or stinger lead

 

[kwired]

I have a client that would like a grounding bar installed in their welding bar...

Did you by chance mean welding booth, or at least some regular workstation where welding is normally performed on smaller objects brought to the workstation.

This would make sense and I have seen that done, maybe not the grounding electrode but just a place to clamp the welder work cable. objects being worked on are sitting on the grounded bench and require no direct connection to the work cable. Makes is easier to reposition the work as the job progresses.

 

[hurk27]

At one time I worked at a structural steel plant and a welder got a wild idea to use the building steel to bond the welder secondary ground to, then he would only have to take the stinger lead with him and put a jumper to where ever he was welding, the problem is it put allot of the building electrical grounding in parallel with it, and in some places there were no other connections but the EGC's, after burning up about 300' of conduit and wiring and EGC's and causing one 200 ton crane to be taken out of service till we rewired it, they found out it was not a good idea.

These welders were very high amperage 600 amps and up, and use Ni-rod at even higher amperages to gouge out bad welds.

So keeping the welders secondary isolated from the building and the electrical grounding can be important.

 

[zbang]

Reminds me of the welder who use the fire sprinkler system as a return for some work 12 floors up on the roof. Fortunately, we didn't get wet, but the building's engineer had a "frank discussion" with him about it.

 

[renosteinke]

I'm not sure what they're trying to accomplish .... that word 'ground' has several different uses here!

Ground rod: I don't see any harm, but if you drive one, it has to be bonded to the reast of the GEC circuit for the building. Bonding to structural iron might qualify in this instance.

Ground bar: A common practice, expecially with smaller pieces. Guys will attach the ground clamp to the workbench, and have the pieces ground through incidental contact with the bench. That's why benches are often copper-coated or made with aluminum; iron doesn't weld to them very well, but they conduct real good. Remember, electricity wants only to get 'home' to where it was made. In this case, that means back to the welding machine. That electricity has no interest in gouing into the earth beneath your feet, into the power grid, or anywhere else.

 

[hurk27]

I'm not sure what they're trying to accomplish .... that word 'ground' has several different uses here!

Ground rod: I don't see any harm, but if you drive one, it has to be bonded to the reast of the GEC circuit for the building. Bonding to structural iron might qualify in this instance.

Ground bar: A common practice, expecially with smaller pieces. Guys will attach the ground clamp to the workbench, and have the pieces ground through incidental contact with the bench. That's why benches are often copper-coated or made with aluminum; iron doesn't weld to them very well, but they conduct real good. Remember, electricity wants only to get 'home' to where it was made. In this case, that means back to the welding machine. That electricity has no interest in gouing into the earth beneath your feet, into the power grid, or anywhere else.

Above in red is not correct see 250.54 While it is permited it is not required.

 

[T.M.Haja Sahib]

The question is whether the leakage current due to welding could kill.Unfortunately,the answer is yes in damp situations and if proper precautions are not taken.In such conditions,the welding return current could 'fan out 'so much so that some of it may flow through the ground to reach the secondary neutral of the welding transformer through neutral earth lead.This would raise the ground potential gradient,thereby hazard to the welder.

 

[iwire]

In such conditions,the welding return current could 'fan out 'so much so that some of it may flow through the ground to reach the secondary neutral of the welding transformer through neutral earth lead.This would raise the ground potential gradient,thereby hazard to the welder.

Welder 'neutral'?

Use the earth as a path?



You will need to explain both of those statements.

 

[T.M.Haja Sahib]

Welder 'neutral'?

Use the earth as a path?



You will need to explain both of those statements.

But do you think a welder could not be electrocuted by the welding current ?

 

[kwired]

But do you think a welder could not be electrocuted by the welding current ?

I'm sure it is possible.

The best thing is to reduce the number of current paths not increase them.

There are only two points of potential - the welder output leads. Keep them as close together as practical and there will be less current paths. The person performing the welding (with a hand held electrode anyway) is in danger of open circuit voltage pretty much at all times anyway - he is holding the one item that has potential to anything else that may be connected to the other lead.

 

[T.M.Haja Sahib]

I'm sure it is possible.

The best thing is to reduce the number of current paths not increase them.

There are only two points of potential - the welder output leads. Keep them as close together as practical and there will be less current paths. The person performing the welding (with a hand held electrode anyway) is in danger of open circuit voltage pretty much at all times anyway - he is holding the one item that has potential to anything else that may be connected to the other lead.

There was one news paper report that a young welder doing his work on a grill in a very damp situation lost his life due to electrocution.It is not clear whether he died due to his accidental bridging of the open circuit voltage as mentioned above or due to flowing of part of ground current component of welding current through him.

 

[kwired]

There was one news paper report that a young welder doing his work on a grill in a very damp situation lost his life due to electrocution.It is not clear whether he died due to his accidental bridging of the open circuit voltage as mentioned above or due to flowing of part of ground current component of welding current through him.

For one thing, the exposure to the welder secondary voltage is just the nature of the beast.

Just like it is not a good idea to stick your hand near the flame when using a torch.

Not knowing any details what are the chances a ground rod at the welder secondary would have made any difference in this accident, especially if proper practice of clamping the ground lead near the work is done.

Most portable welders have fairly short leads - makes it difficult to not have both output leads close together, probably for good reason.

 

[T.M.Haja Sahib]

Not knowing any details what are the chances a ground rod at the welder secondary would have made any difference in this accident, especially if proper practice of clamping the ground lead near the work is done.

I too think that a ground rod at the welder secondary might have no effect.May be that accident happened this way:The earth lead was connected to the grill at a remote place from the actual welding point.The return current not only flowed through the grill but also part of it through the damp ground before entering the secondary neutral via the earth lead.This ground current might have killed the welder.

 

[iwire]

before entering the secondary neutral via the earth lead.This ground current might have killed the welder.

There is no neutral.

 

[iwire]

Let me elaborate, the output of a welder is typically two wire, one called 'work' and one called 'electrode'.

Neither of those leads are connected to anything until the person doing the welding connects them to something.

The only path to the secondary winding is via these two leads, the equipment grounding conductor plays no part in the secondary side circuit.


Things I have seen done that have not worked out to well.

A welder backed his truck up to a loading dock and connected his 'work' lead to the dock leveler, he draged his 'electrode' lead into the building and went about welding on the structural steel inside the building.

Because the dock plate was isolated from the building steel except for the grounding conductor, this resulted in melting the equipment grounding conductor connected to the dock plate and required about a days work to fix.


Another time at a building with cement walls and a steel roof a welder connected his 'work' lead to a 1/2" EMT just inside the door of the building and then went to work welding on the roof.

This melted the EGC inside the EMT and melted out a couple of the EMT connectors.

 

[T.M.Haja Sahib]

There is no neutral.

Replace ''earth lead'' by ''work lead'' and ''secondary neutral via the earth lead'' by
'' work lead'' in post #14 (as desired by you). Then does the explanation given in post #14 make sense to you?


​

 

[iwire]

Replace ''earth lead'' by ''work lead'' and ''secondary neutral via the earth lead'' by
'' work lead'' in post #14 (as desired by you). Then does the explanation given in post #14 make sense to you?​

Well I have no idea why you would have called that a neutral but be that as it may post 14 still makes no sense as the work lead is not intentionally connect to earth at all. From the electrode lead there is only one path back to the welder machine and that is via the work lead.​

 

[T.M.Haja Sahib]

.......post 14 still makes no sense as the work lead is not intentionally connect to earth at all. From the electrode lead there is only one path back to the welder machine and that is via the work lead.

What about the unintentional connection of the work lead to the ground through the grill work which was fixed to the ground and on which the welder was doing his work?

 

[kwired]

Well I have no idea why you would have called that a neutral but be that as it may post 14 still makes no sense as the work lead is not intentionally connect to earth at all. From the electrode lead there is only one path back to the welder machine and that is via the work lead.

What about the unintentional connection of the work lead to the ground through the grill work which was fixed to the ground and on which the welder was doing his work?

And exactly why people that weld should follow certain safety procedures. We talk a lot on this forum about live work and arc flash protection. I'm not a professional welder, and my welding skills stink. But I would guess anyone that has some formal training has gone through some safety training to include the importance of wearing protective gear such as face shield, long sleeves, flame retardant clothing, gloves, etc. They also probably learn a little about the electric current that is used to do a very important part of what they are doing. Maybe not all the details that an electrical worker learns but they need to understand where that current is/can flow if work lead is not close to the work.

I guess that if your job requires you to weld there are OSHA regulations that many of us don't ever see or think about.