Welder Grounding

[hurk27]

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?

What your not understanding is the output leads of a welder have no reference to ground, Earth, or any other item that servers in place of ground, welding on a piece of metal sitting on ground will still not cause current to try to flow back to the welder machine.

The secret to welding without getting shocked is isolation, many use mats to stand on, all use gloves, but the important thing to not damage other electrical systems is to not use the building as part of the current paths as I posted about before, bonding the welder work lead creates a reference to Earth that would not normally be there, this is a mistake that many welders do thinking the current wants to return to Earth, they think doing this will remove the shock hazard, this is a myth that many non-electricians do not understand and even some electricians that still think this way, by not grounding the work lead you have a much less reference area located only in the area of the work being welded, if the items that are being welded are also bonded to a grounding system then care must be taken to put the work lead as close to where the work being done is, and care must be taken by the operator doing the work to not get between the metal that is grounded and his stinger lead, the fact that the work is grounded has no effect on the safety of the operator other then he better be waring shoes that provide electrical isolation from the ground he is standing on, remember we are not talking about very high voltage, most OCV is barely over 100 volts, so most shoes would provide isolation from this voltage with no problems.

The operator who sweats allot should also put a isolation mat down, but what about high steel welders, in most cases they are sitting right on the beams they are welding, again they must take care to keep themselves isolated from the stinger lead, watch for frayed cables is a must, and when inserting and or removing a welding rod in the stinger, they should have a dry pair of gloves on.

 

[Besoeker]

The operator who sweats allot should also put a isolation mat down, but what about high steel welders, in most cases they are sitting right on the beams they are welding, again they must take care to keep themselves isolated from the stinger lead, watch for frayed cables is a must, and when inserting and or removing a welding rod in the stinger, they should have a dry pair of gloves on.

Typically, what sort of voltages do welders (the kit, not those who use it) operate at?

 

[iwire]

Typically, what sort of voltages do welders (the kit, not those who use it) operate at?

I believe open circuit voltages are often around 70 volts.

 

[hurk27]

Some of the power heads we had at Allied Structural Steel had an OCV of 110, but like Iwire stated most are 100 volts or less, it is very common as it is not the voltage they need but the current, with just enough voltage to maintain the arc.

 

[mikeames]

I have this welder (180 amp 240v) and measured 240v AC and 18v DC between the wire and the work clamp

I used this meter

 

[socalelect]

gloves will not prevent you from getting bit if the humidity is high . i know this from exp . it has happened several times to me when inserting a new rod usually thru the left arm and out my leg it hurts bad . so now ive turned into a little girl and i set the rod down and "grab" it with the stinger


as far as " open circuit voltage " when runnin constant current i think its limited to 70 volts DC and its lower on when running AC output
the welder i use most often has a constant voltage function on that setting ocv is 40 volts dc max but unlimited current of the machine which is 400 amps

osha has a bunch of rules for max open circuit voltage for welders espicially on AC output , but ac is generally only used for high freq tig and the cheapy home depot stick welders

as far as connecting the work lead as i said in the begining of this thread its best to ground as close as practical to where you are welding

i have seen guys welding on equipment and connected at one end and welded on the other end and arced a bunch of bearings together

 

[hurk27]

I have this welder (180 amp 240v) and measured 240v AC and 18v DC between the wire and the work clamp

I used this meter

Not sure where you are reading the 240 volts AC from but according to the factory spec's for that machine it is a DC machine with an OCV of only 33 vdc which can be read here:
http://www.lincolnelectric.com/assets/en_us/products/k2698-1/e745.pdf
Scroll down to the bottom for the spec's
Many meters will read funky readings when using an AC setting to read DC, if the power supply is a switching type, the meter is reading the caps voltage and it is something of a ghost voltage that will go away when loaded, try placing a 120 volt 100 watt lamp across the work lead and stinger and I bet it barely lights.

 

[Besoeker]

Not sure where you are reading the 240 volts AC from but according to the factory spec's for that machine it is a DC machine with an OCV of only 33 vdc which can be read here:
http://www.lincolnelectric.com/assets/en_us/products/k2698-1/e745.pdf

I was thinking that in could be of that order.
We're manufacturing some welding rectifier systems at the moment and they are rated 10Vdc on load. They'd probably give a couple or so more on open circuit.
Welders are not my area of expertise but I would have though the risk of fatal electrocution from the output was pretty minimal.

 

[iwire]

I was thinking that in could be of that order.
We're manufacturing some welding rectifier systems at the moment and they are rated 10Vdc on load. They'd probably give a couple or so more on open circuit.

A great many stick welders are straight up AC.

Welders are not my area of expertise

Nor mine but I have done a fair bit of Arc, MIG and some TIG welding and I can tell you without a doubt you can get lit up pretty well if you are not paying attention. Water is a game changer. When you are trying to weld a repair on say, a snow plow that is still packed with melting snow, or working in the blazing sun and sweating a lot ......... well it can surprise you.

but I would have though the risk of fatal electrocution from the output was pretty minimal.

I think that sums it up, it is possible and it has happened but the chances are low. I bet more people die choking on hard candy.

 

[GeorgeB]

I was thinking that in could be of that order.
We're manufacturing some welding rectifier systems at the moment and they are rated 10Vdc on load. They'd probably give a couple or so more on open circuit.
Welders are not my area of expertise but I would have though the risk of fatal electrocution from the output was pretty minimal.

Perhaps those are for a spot welder; voltages are much lower. "Typical" arc voltages are in the 20-35V from what I've seen. The transformer design in "buzz-box" welders has (to we electrical guys) unusual characteristics, kind of a cross between constant current and constant voltage. Lincoln Electric's FAQ includes: Q: What voltages are used in the arc welding process?
A: Arc welding involves open circuit (when not welding) voltages which are typically from as low as 20 volts to as high as 100 volts.

 

[T.M.Haja Sahib]

What your not understanding is the output leads of a welder have no reference to ground, Earth, or any other item that servers in place of ground, welding on a piece of metal sitting on ground will still not cause current to try to flow back to the welder machine.

If you followed my posting in this thread,you could see the damp ground caused some of the welding return current to take the path through it before its returning to the transformer secondary through the work lead connected to the grill work .This leakage ground current might have caused the fatal accident of post #12.But do you any other explanation for the said fatal accident that I did not understand?

but what about high steel welders, in most cases they are sitting right on the beams they are welding,

Simple.Even though welding current still follows through it,the body resistance of welder is very much higher compared to the beam and so negligible amount of current flows through him with no harmful effect, just as there is no harm to birds perching on overhead power lines.

 

[iwire]

If you followed my posting in this thread,you could see the damp ground caused some of the welding return current to take the path through it before its returning to the transformer secondary through the work lead connected to the grill work .This leakage ground current might have caused the fatal accident of post #12.But do you any other explanation for the said fatal accident that I did not understand?

None of us have any facts at all to draw a conclusion.

Here is all we have been provided.

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.

The only fact I can gleam from that is that you posted it.

 

[T.M.Haja Sahib]

None of us have any facts at all to draw a conclusion.

Here is all we have been provided.

http://forums.mikeholt.com/showthread.php?p=1357543#post1357543 ''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.''

You could eloborate,if you are pleased, what kind of ''facts'' are required to draw a conclusion.

 

[don_resqcapt19]

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

Actually since the open circuit voltage of many welding machines is over 50 volts there is a shock hazard and NFPA 70E and the OSHA rules require the use of 1000 volt rated gloves

 

[T.M.Haja Sahib]

Actually since the open circuit voltage of many welding machines is over 50 volts there is a shock hazard and NFPA 70E and the OSHA rules require the use of 1000 volt rated gloves

What about the safety footwear for the welder?

 

[iwire]

You could eloborate,if you are pleased, what kind of ''facts'' are required to draw a conclusion.

:slaphead::slaphead:

 

[roger]

You could eloborate,if you are pleased, what kind of ''facts'' are required to draw a conclusion.

Most people would want more than a news paper or magazine article for facts. Can you provide us with who did the investigation and forensic work to determine the cause of death? Can you provide the actual OSHA (or what ever agency) documentation? With out something a little better that a reporters article we have nothing substantial.

Roger

 

[iwire]

Most people would want more than a news paper or magazine article for facts. Can you provide us with who did the investigation and forensic work to determine the cause of death? Can you provide the actual OSHA (or what ever agency) documentation? With out something a little better that a reporters article we have nothing substantial.

Maybe I overlooked it but I don't even think we got a link to the article.

 

[Besoeker]

Most people would want more than a news paper or magazine article for facts.

Completely agree.
One of my guys had an incident at his house about a month ago. The fire service was called.

It was reported in thus in the local rag:

Firefighters were called to a house in South ** after overloaded plug sockets started an electrical fire.
The occupants smelled smoke at 6am and evacuated their home, in **** Street, before two fire engines from the Walford station arrived.

The living room of the property suffered minor fire and smoke damage before crews were able to extinguish the flames and move the furniture outside.

Attending officer DE said the occupants were fortunate the fire was not more serious.

He said: ?They had a lucky escape ? there were nearly 12 extension leads plugged in to one another. In the run up to Christmas this is the time we want to be reminding people to make sure they don?t over load plug sockets. Make sure that when you?re pulling lights out of the loft they have been safety tested.?

This is actually what happened:

Just wanted to clarify a few things about the electrical fire. The occupants weren't evacuated, nor was the furniture!! There were 2 extension leads not 12 (that had adaptor plugs in).There wasn't even a fire just singeing on the curtain,it was noticed before a fire started. And the cause of the electrical fault??
The old cat they had decided to wee on the plugs which caused it to fuse !!! Something that could not have been foreseen.

 

[T.M.Haja Sahib]

Most people would want more than a news paper or magazine article for facts. Can you provide us with who did the investigation and forensic work to determine the cause of death? Can you provide the actual OSHA (or what ever agency) documentation? With out something a little better that a reporters article we have nothing substantial.

Sorry,I have none other than what I stated in post #12.

But I am afraid you missed my point.

I just wanted to explore the possibility of death by ground leakage current due to welding return current on the basis of that fatal accident, as there is no way to establish the actual cause of that welder's death due to lack of sufficient data at hand.