Welder Ground Lead

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zbang said:
Floods?

And many fire inspectors get really shirty about anything attached to a sprinkler pipe. If you're not supposed to use the sprinkler pipe to support some CAT5, then using it as a 100amp conductor is probably also prohibited. I'll ask my friend who used to be a sprinkler fitter next time I see him.
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So it is just a "not MY pipes" thing. The welding current ain't gonna hurt it. Wonder what kind of current/voltage spike it sees on a lightning strike, being grounded to the building and being a nice straight run of metal.
 
MAC702 said:
So it is just a "not MY pipes" thing. The welding current ain't gonna hurt it. Wonder what kind of current/voltage spike it sees on a lightning strike, being grounded to the building and being a nice straight run of metal.
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After your years of welding experience and then electrical experience to add, you should be promoting a safer workplace, not supporting these bad habits. Know better already.
 
mivey said:
After your years of welding experience and then electrical experience to add, you should be promoting a safer workplace, not supporting these bad habits. Know better already.
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I'm acknowledging this is a common practice, not so much advocating it, but also recognizing lack of evidence it causes problems.

You can help discuss WHY you think these are bad habits, or you can just label them and move on.

We've even had an unrecanted, unsupported post that says using building steel is illegal...
 
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MAC702 said:
I'm asking for evidence, not lectures.

I'm acknowledging this is a common practice, not advocating it.

You can help discuss WHY you think these are bad habits, or you can just label them and move on.

We've even had an unrecanted, unsupported post that says using building steel is illegal...
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It seemed to me that your posts were supporting the practice. Sorry if I misread that.

I have said why they are bad practices.

Using the building steel as a working conductor and having the work lead far removed from the work zone is contrary to welder instructions and seems to me it would make the welder liable for damage/injury/death. The resulting penalty that could result certainly points to the activity being non-legit/illegal.
 
mike7330 said:
http://www.ecmweb.com/shock-electro...welding-current-damage-your-electrical-system
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Here are a few choice points from that:
For 12 years, I worked as an incident investigator, primarily doing electrical accident investigations that involved electric welding incidents, stray welding current and shock investigations, electrical burns, electrical explosions, fires, and fatality consultations.
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What we found when we became involved with welding incident investigations was that many stick welders (SMAW) suffered hundreds more electric shock incidents than electricians.
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Let’s think about what is available to carry the welding current. There is the building steel, the building grounding system, the many electrical circuit ground conductors, and maybe a few coaxial cables.
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Welding current flowing in anything but the welding cables designed to carry it can cause significant damage in a building’s electrical system.
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The truth is many times the damage is not immediately recognized — maybe there was no visible damage during this onetime event as the current load splits through those multiple paths. But that’s not always the case. I remember consulting on one fatality investigation in which the end result of stray welding current and an incomplete electrical inspection before power was restored. The victim died instantly due to a 420mA electrical current flowing across his chest.
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In a more recent event in a welder training facility, stray welding current overheated the ground conductor, which melted through a phase conductor inside a welder power receptacle and caused an electrical explosion (Photo 4) and the protective device to operate.
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Only correct positioning of both welding leads at the site of the welding process will control stray welding current. Otherwise, with the welding arc, high current extra low-voltage electric power is free to roam indiscriminately throughout your building.
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mivey said:
It seemed to me that your posts were supporting the practice. Sorry if I misread that.

I have said why they are bad practices.

Using the building steel as a working conductor and having the work lead far removed from the work zone is contrary to welder instructions and seems to me it would make the welder liable for damage/injury/death. The resulting penalty that could result certainly points to the activity being non-legit/illegal.
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As both an electrician since 1998 and a weldor since childhood, I admit I am torn, and may not be presenting my case well.

I'm really trying to see IF there is a real problem with this beyond the "how dare they?" concern. I see a lot of disdain for the practice, but from us as electricians. Aside from this issue with the MC, have there been incidents? And while this MC arcing was not kosher, it also got noticed and fixed and no damage was done. There is always the possibility of something during construction causing fires or damage, but is this one of the ones that's been to blame?

I've posed the question on the forum at Miller Welding, where I've been a contributing member since its inception. My welding experiences are not usually on the kinds of jobs that posed the OP.
 
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ecm article said:
...with the welding arc, high current extra low-voltage electric power is free to roam indiscriminately throughout your building.
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Indiscriminately?

The same paths the welding current is taking is used for lightning strikes. The latter is completely outside my realm of study or expertise, but it makes me wonder which is worse, and therefore if either is necessarily relatively bad.

A good weldor makes good decisions about his work clamp, and like with most trades, a bad weldor is probably dangerous in far more concerning ways.
 
MAC702 said:
Indiscriminately?

The same paths the welding current is taking is used for lightning strikes. The latter is completely outside my realm of study or expertise, but it makes me wonder which is worse, and therefore if either is necessarily relatively bad.

A good weldor makes good decisions about his work clamp, and like with most trades, a bad weldor is probably dangerous in far more concerning ways.
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Not the same characteristics (duration, frequency, etc.)

Think about a 10,000A brief lightning strike on a conduit vs a 10,000A relatively long-term load current.

Same goes for a fraction of a second 100A strike vs a long-term welding current of 100A.

I don't think anyone would say lightning is good but it is certainly an unplanned event rather than a planned purposeful event.
 
MAC702 said:
... Aside from this issue with the MC, have there been incidents? ...
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Both Don and the magazine article have described other incidents.
It didn't take me long with google to find more, , including on this forum:
Welding currents go astray.
http://forums.mikeholt.com/showthread.php?t=158601
http://forums.mikeholt.com/showthread.php?t=169337

And while this MC arcing was not kosher, it also got noticed and fixed and no damage was done.
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Um, how do you know that no damage was done?

There is always the possibility of something during construction causing fires or damage, but is this one of the ones that's been to blame?
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Seems like the damage part is indisputable. Quantifying is something else, but it seems it happens.


MAC702 said:
Indiscriminately?

The same paths the welding current is taking is used for lightning strikes.
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Um, no, I don't believe that is true. To my knowledge no designer of a lightning protection system would use electrical system conduits as part of the LPS. And it is also pretty irrelevant to compare a natural phenomenon over which we have relatively little control to a human initiated process over which we have a lot.

A good weldor makes good decisions about his work clamp, and like with most trades, a bad weldor is probably dangerous in far more concerning ways.
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I can agree with that. I would probably put the OP example in the bad decisions camp though, if as was described they have their electrode at various locations up to 200ft away with no regard to moving the work lead clamp appropriately.
 
jaggedben said:
Um, no, I don't believe that is true. To my knowledge no designer of a lightning protection system would use electrical system conduits as part of the LPS. And it is also pretty irrelevant to compare a natural phenomenon over which we have relatively little control to a human initiated process over which we have a lot.
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???
LPS is required to be tied to EGC....... and metal conduit is too. kinda inherent by the rules of NEC. thats not my view though on how LPS should be done.
 
MAC702 said:
As both an electrician since 1998 and a weldor since childhood, I admit I am torn, and may not be presenting my case well.

I'm really trying to see IF there is a real problem with this beyond the "how dare they?" concern. I see a lot of disdain for the practice, but from us as electricians. Aside from this issue with the MC, have there been incidents? And while this MC arcing was not kosher, it also got noticed and fixed and no damage was done. There is always the possibility of something during construction causing fires or damage, but is this one of the ones that's been to blame?

I've posed the question on the forum at Miller Welding, where I've been a contributing member since its inception. My welding experiences are not usually on the kinds of jobs that posed the OP.
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The cases I have worked on were where there was LFMC in part of the circuit that was carrying the welding current. In most cases it was just the LFMC and the wire in it that were damaged. In some cases, the internal EGC in the conduit also carried enough current to melt the insulation and make removal of the conductors impossible requiring conduit replacement. I don't think I have seen any issues where just the metal conduit itself was the welding current path, but I can see where it could be if someone had not tightened the couplings. Have also had to replace load cells where the load cells became part of the path because of the remote welding lead connection.
 
FionaZuppa said:
???
LPS is required to be tied to EGC....... and metal conduit is too. kinda inherent by the rules of NEC. thats not my view though on how LPS should be done.
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To my knowledge the NFPA favors tying the LPS to the grounding electrode system, not the EGC per se. If done right, I believe there is no general reason why lightning current should be prone to travel on EGCs throughout the building. Lightning wants to go to ground, and the down conductors will hopefully carry it there without sending it onto EGCs and conduits that aren't in the path. Of course there are instances where makes its way where its not wanted, but I believe it's wrong as a general statement to say that significant lightning current routinely travels all over the electrical systems in buildings with well designed LPSs.
 
jaggedben said:
To my knowledge the NFPA favors tying the LPS to the grounding electrode system, not the EGC per se. If done right, I believe there is no general reason why lightning current should be prone to travel on EGCs throughout the building. Lightning wants to go to ground, and the down conductors will hopefully carry it there without sending it onto EGCs and conduits that aren't in the path. Of course there are instances where makes its way where its not wanted, but I believe it's wrong as a general statement to say that significant lightning current routinely travels all over the electrical systems in buildings with well designed LPSs.
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That is a fair assessment.
 
did i miss something. doesnt the EGC have to tie to the GEC at some point?
once tied, 4 million volts travels everywhere, everything has some ohms :thumbsup:
 
FionaZuppa said:
did i miss something. doesnt the EGC have to tie to the GEC at some point?
once tied, 4 million volts travels everywhere, everything has some ohms :thumbsup:
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That may be true to some degree but current and voltage have to be present to exchange energy. You can dump a bucket of water in a basin, but the water runs down the drain (the grounding electrode / electrode system). Other currents may be present if there are weak points (flashovers, other earth bonds, etc.)
 
mivey said:
That may be true to some degree but current and voltage have to be present to exchange energy. You can dump a bucket of water in a basin, but the water runs down the drain (the grounding electrode / electrode system). Other currents may be present if there are weak points (flashovers, other earth bonds, etc.)
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4,000 amps to gec, 300 amps across egc
does it really matter how you dump your bucket?
 
I think the more general point is that lightning currents are not comparable to welding currents in either behavior or duration. It does not follow that the welding currents are safe because lightning currents may, in the odd circumstance, travel over the same metal without causing damage. And of course, sometimes lightning on EGCs does cause damage.
 
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