How much damage could I have really done

[pbfourever]

So let me start from the beginning. It was about 10 pm getting ready to shut down for the night in the fab shop I work in. I was finished welding and there was another guy welding tig alum. grounded on the same 40 foot table as mine. I went to take MY ground off but took his off on accident. He also had a damn stable arc going when I popped that ground off. I was holding the table he was welding on and had the ground firmly in my hand. I know I was pretty fortunate but what could it had done. He was running about 250 amps.

[zapster]

Nothing..

You are still standing arn't you?

I would have punched you for inturupting my weld but that would be it..

Unless YOU were holding the torch then nothing but a black eye...

The ground was completed thru your machine even though it was not on..


...zap!

[Bikespot]

Is it even possible to kill your self some how?

What if you held the end of the torch and the ground and turned it on? Then electricity would be going through you.

[TEK]

[QUOTE=zapster;183024]Nothing..
I dont agree....you were very lucky he was only at 250amp. Anything over that and you may have torn a hole in the fabric of space and we all would of died...


The ground was completed thru your machine even though it was not on..

I dont quite follow that one.......

[drivethruboy54]

i should think there isnt suficient voltage to have messed you up too bad. Voltage is pressure in electricity, and closed circuit voltage being on average below 20 volts, thats not enough push to go overcome the resistance from the body.

Once the ground breaks contact with the work, it will arc between the ground clamp and the work, and will lose even more voltage. The biggest voltage drops in welding occur across the arc, so your losing even more pressure and limiting the current flow through the leads.


i could be wrong, but ive pulled grounds off by accident before running 232 at over 300 amps, in the mud and rain, nothing happens except a REALLY angry welder. Electricity is not my thing, but im fairly certain i have the right idea...

[Tensaiteki]

Nothing..
The ground was completed thru your machine even though it was not on..

I disagree. This is the problem with people calling it a "ground clamp" instead of the more technically correct "work lead/work clamp." On a typical setup the work lead is not connected to an earth ground (or the ground wire in the electrical system). The only way the circuit could've been completed through his machine is if both machines had their work leads (inexplicably) connected to an earth ground, in which case the circuit would go from the torch, to the work, to the table, to the work lead on the other machine, to the earth ground connection, to the earth, to the earth ground connection on the active machine, then to the work lead connection on the active machine.

As far as danger, it really depends on your hands. When I run GTAW my voltage rarely gets over 11-12V. This voltage is not sufficient to overcome the resistance of dry skin or dry gloves. However, if your hands and.or gloves are sweaty or otherwise wet, you could get a dangerous shock right across the heart (especially with one hand on the table and one on the work clamp). While you can very easily receive a fatal shock under these circumstances the resistance of the body (even wet) will not let the full welding current pass.

Assuming your hands were dry, the biggest danger (aside from the aforementioned angry weldor) would be the flash from the arc that would almost certainly be created between the clamp and the table as it is removed. This arc would also damage the clamp.

[MAC702]

Ditto.

[chopper5]

it can shock the S!!!! out of you :dizzy:

[wlbrown]

HELLO,
why would you remove the ground?
wlbrown

[MAC702]

Why not? Sometimes I do, if I'm going to sweep my area, or otherwise want to leave my work area in a neat manner.

[pbfourever]

HELLO,
why would you remove the ground?
wlbrown

because the two ground were next to each other and i only saw one of them at the time and it happened to be the one that was in use.

[Cruizer]

Realistically not much, you can touch both positive and neg terminals with dry hands and maybe get a light shock if you have office workers hands, There is just too much internal body resistance to feel much. With wet hands you'll feel a little more.

[deadman1474]

[QUOTE=zapster;183024]Nothing..
I dont agree....you were very lucky he was only at 250amp. Anything over that and you may have torn a hole in the fabric of space and we all would of died...


The ground was completed thru your machine even though it was not on..

I dont quite follow that one.......

I agree with zap 100% electricity takes the path of lest restiance and there was a different ground on the table that it would take. It's not going to keep welding but its also not going to kill you in my opinion. Unless you rilly piss off the welder.

[Nomand]

All over the world upto 36V AC/DC is considered to be a safe voltage - used in mines, confined spaces, factories etc. I beleive that even if you wanted (wetting hands, gloves etc) you would not be able to kill yourself this way. But you might ruined guy's work though...

[Mandau]

Lucky u have yur shoes and glove on... or else... god bless ya:)

[Donald Branscom]

It is ILLEGAL for two welders to be working at the same table at the same time for that VERY REASON!

Argue if you want, but you are lucky to be alive. Just think if the OTHER guy died!

If you do not believe me, check with the American Welding Society.
Why do you think welding schools have special considerations about grounding for that reason.

It only takes ONE AMP to Kill a person. What saved you is the fact that when that ground was diconnected the ground found the next best path and luckily it was better than the one you were holding.

[zapster]

It is ILLEGAL for two welders to be working at the same table at the same time for that VERY REASON!



Then explane to me why we had 5 guys welding on the same 40 foot platen table when I did military work?
All day every day!
One on a mig and 4 on tig..
I can see where 5 guys on one ground would be a problem but that's not the situation..

This ought to be good.

...zap!

[TSOR]

Does the military follow the same rules??

[ironken]

It is ILLEGAL for two welders to be working at the same table at the same time for that VERY REASON!

Argue if you want, but you are lucky to be alive. Just think if the OTHER guy died!

If you do not believe me, check with the American Welding Society.
Why do you think welding schools have special considerations about grounding for that reason.

It only takes ONE AMP to Kill a person. What saved you is the fact that when that ground was diconnected the ground found the next best path and luckily it was better than the one you were holding.

Dude, I have read a few of your posts and they are all far too serious! You are no dummy. I can see that from some of the info you give. But, sheesh...lighten up! Yes, electrical shock can kill. Welding can be dangerous. But, the way you spell it out, it is like we defy death every time we flip on the machine. Common sense applies to all industry. Maybe the Discovery Channel should be contacted to do a reality show called, "The Deadly Arc, and the Maverics Who Defy Death and Harness it."

[zapster]

Does the military follow the same rules??

Naaaaa
They have their own set of rules..

...zap!

[DSW]

It is ILLEGAL for two welders to be working at the same table at the same time for that VERY REASON!


What about ship welding? You think Newport News only has one welder working on a section at one time? (Maybe that explains cost overruns, the more sections you add the fewer welders can work!) From my understanding it is critical to be sure the machines are set propperly when welding with 2 machines on the same object. I don't have that worry so I can't give any more info than what I learned long ago.

[zapster]

I just got off the phone with my brother..
Master Electrician Licence here in Mass working for NStar..

He said you could have 20 machines going at the same time if the ground thru the one machine could handle it at one time..
There is only one common ground wire coming into the building and everything electric eventually goes to the same place now don't it?

Dont matter he said if the machine or whatever is on or off in that reguard..

Kinda explanes why I fried the ground wire from the positioner cord one day when the ground cable fell off the positioner...

Learn something new everyday now don't we..:)

...zap!

[BiGs]

Ive been shocked a few times on AC while tig welding, its not fun. I prefer the tingling of the DC shocks. 250amp AC would have been a hell of a jolt.

[denrep]

...He said you could have 20 machines going at the same time if the ground thru the one machine could handle it at one time....
I would disagree, he probably misunderstood the hypothetical questions.

Just not possible that any one machine would have the ampacity to handle the "work" load of 20 machines. Although 20 machines, each with it's own loop, could certainly work together

...
There is only one common ground wire coming into the building and everything electric eventually goes to the same place now don't it?

No, everything electric does not go to the same place.

Earth ground of the building's electrical service is not the same as, -and should not be confused with- the path or loop of a welders secondary "work" (ground) circuit.

But as for the work clamp being pulled off while welding; I agree... no big deal.

[deadman1474]

I would disagree, he probably misunderstood the hypothetical questions.

Just not possible that any one machine would have the ampacity to handle the "work" load of 20 machines. Although 20 machines, each with it's own loop, could certainly work together


No, everything electric does not go to the same place.

Earth ground of the building's electrical service is not the same as, -and should not be confused with- the path or loop of a welders secondary "work" (ground) circuit.

But as for the work clamp being pulled off while welding; I agree... no big deal.

Zap please correct me if I am wrong but what I think that you are trying to say is that you are not going to be able to weld off of the other welders ground.

But since electricity takes the path of least restince it is going to go from your gun to the other machines ground. It won't still weld but at least you will be still be here. Now I just wonder if there was only one welder on that table and you took his ground camp off since there was no other welder to be grounded out to would this be worse for you??

Well I will ask one of the electrical enginers tommarow and we will finally be able to settle this once and for all,
Cody

[MAC702]

It is ILLEGAL for two welders to be working at the same table at the same time for that VERY REASON!...

Illegal where and enforced by what agency?

[denrep]

...But since electricity takes the path of least restince it is going to go from your gun to the other machines ground....

...Now I just wonder if there was only one welder on that table and you took his ground camp off since there was no other welder to be grounded out to would this be worse for you?? ...

Sometimes the path of least resistance, is for current not to overcome the resistance, and not flow; especially with low voltages. For example - Without worry, you can grab both terminals of your truck's battery, and it may have a potential for delivering 1000 amps.

The terms ground, negative, and work, are confusingly similar, but not the same.

Think about the "ground" circuit... In straight polarity, the work clamp is positive, and the electrode is negative. If the welder's output negative terminal was connected to the buildings ground, via ground wiring, then the moment you connected the "positive" work clamp to a "negative" grounded piece, you would have a welding circuit.

The welder's output circuit, is separate and isolated from the input circuit. That's why several welders, even at different polarity or current settings, can weld on the same piece. Each welder is operating on it's own current loop.

When the relatively low voltage welding circuit was broken by removing the work clamp, current simply quit flowing; it did not desperately seek an alternate path, as a high voltage current would.

But... Don't get complacent about any electric circuit. There is always the possibility of freak and stray currents, through unforseen current paths, or back feeds.

Shared work clamps have been studied before:
http://weldingweb.com/showthread.php?p=145687&highlight=work+clamp#post145687

[MoonRise]

Safety note:

Even a 12 volt vehicle battery can KILL you, if certain conditions occur.

Usually, your skin resistance is high enough that no/minimal current can flow from a 12V source (the battery). Even if your hands are slightly damp, you are -probably- OK with 12V.

But, if you were to make a connection across the battery terminals to a more conductive substance -inside- your body, like if there are burrs on the battery terminals and you put your thumbs across both terminals and the burrs punctured your skin enough to reach blood, you have just put a 12V (actually 13+V or so) source capable of sufficient amperage to flow through the nice conductive salty blood right from one thumb up the arm and across the heart and down the other arm and out the other thumb.

BAM! You're dead.

Take the appropriate safety precautions needed for the task.

And I do believe that I read some reg somewhere that yes indeed running multiple work-clamps ('grounds') to the same workpiece/table at the same time is 'illegal'. Some of my neurons are mumbling maybe 'California OSHA' or something like that. I don't feel like searching deeper.

[zapster]

Man 'O Man!
We can really dig into anything as a community now can't we...:cool2:

...zap!

[boatbuoy]

"It is ILLEGAL for two welders to be working at the same table at the same time for that VERY REASON!"
where can i find this rule ,law,or regulation?? osha doesn't mention such a thing. the alaska pipeline would still just be a dream if only one welder could work on it.

[Jonesy70]

Bottom line...becareful as to which ground you remove...Elecricity DOES travel the path of lease resistance. there was not enough "pressure" to over come your bodies resistance to be shocked!!...I have done the same thing before but only been custed at or had things thrown at me...consider us both luckey those times...I have only been shocked while welding in the rain (I can be such a brain surgen at times) or because I was so sweaty that I might has well been douced by a bucket of water!!! I tryed to put a rod in my stinger and BANG...I took a hit...not much more than a sting..but enough to make my hair stand up on my neck!!

So becareful