Silly Q re electrocution

Guess a Q re being electrocuted is not really silly, at least not as silly as NOT asking it!
Anyhow, I have a Steel Work bench top. Idea was to clamp the earth lead to
the bench top, clamp the 'part' to the bench and the weld away.....
Right now I have a Stick welder (actually had it for a while - just never managed to learn to use it that well as everything I've need to do has been thin material) but I plan to get a MIG @ xmas from Santa.
Anyhow my Q, is If I touch one arm (for example) against the bench top and then touch the stick (eg changing it to a new one) or some such....am I risking a 'wake up' call? Normally I've powered down the stick welder to change, but occasionally I haven't & with the MIG I just wondered what happens if I accidently touched the tip / wire while leaning / resting on the benchtop?
BTW I normaly wear gloves anyhow, so this is really just a "what if" type question.
TIA for any info.
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FredBear <Fredbear2412(via)yahoo.com.au> wrote: : Guess a Q re being electrocuted is not really silly, at least not as silly : as NOT asking it!
: Anyhow, I have a Steel Work bench top. Idea was to clamp the earth lead to : the bench top, : clamp the 'part' to the bench and the weld away.....
: Right now I have a Stick welder (actually had it for a while - just never : managed to learn to : use it that well as everything I've need to do has been thin material) but I : plan to get : a MIG @ xmas from Santa.
: Anyhow my Q, is If I touch one arm (for example) against the bench top and : then touch the stick : (eg changing it to a new one) or some such....am I risking a 'wake up' call? : Normally I've powered down the stick welder to change, but occasionally I : haven't & with the MIG : I just wondered what happens if I accidently touched the tip / wire while : leaning / resting on the benchtop?
: BTW I normaly wear gloves anyhow, so this is really just a "what if" type : question.
: TIA for any info.
Well, it really is best to follow the safety instructions included in your owners manual. Some stick welders have open circuit voltages around 90+ volts and can give a pretty good bite. It can be more dangerous if it is AC.
The work cable should not be considered a ground. It is not. To ground your table (a good idea), you should run a ground wire to a water or gas pipe.
I would pick the safer method and turn off the machine when changing electrods or when not welding. I would not trust the gloves to provide the insulation. Sweat will make them conductive and leather has a lot of salts from the processing.
If you are doing tig with HF, you will soon learn to turn off the machine.
Regards, Tom
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Actually DC is more dangerous, especially at high voltages. AC at least shakes you and gives you *some* chance of breaking loose. DC locks the muscles into a cramp where you have little chance of breaking free. Because DC is usually used in low voltage classification, it rarely happens. The 110V DC generators on older welding machines are very dangerous. A good example of what happens is to take a solenoid and apply rated voltage with DC then AC.

Very true. I'm not sure if it's a good idea to ground the secondary winding of your welder by grounding the work table. It would be better to follow the recommendations of the manufacturer or if I may suggest, Gary Coffman here on the NG.

gas pipe.
Never never never to a gas pipe in the rare event something goes wrong. It is bad enough to wire a ground to a "hot" water pipe. The Water Heater gaskets etc. create spark gaps that will burn holes in the pipe instantly. I hate to think what would happen if there were a spark gap somewhere in the gas pipe grounded to a welder or power system.
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:>Some stick welders have open circuit voltages around 90+ :>volts and can give a pretty good bite. It can be more dangerous if it is :>AC.
: Actually DC is more dangerous, especially at high voltages. AC at least shakes : you and gives you *some* chance of breaking loose. DC locks the muscles into a : cramp where you have little chance of breaking free. Because DC is usually used : in low voltage classification, it rarely happens. The 110V DC generators on : older welding machines are very dangerous. A good example of what happens is to : take a solenoid and apply rated voltage with DC then AC.
I believe you have it backwards. Muscles respond to a pulsing nerve stimulation to maintain a contraction. They will only react once to dc then they depolarize. It is an AC signal that will cause you to grip the conductor and be unable to release.
:>The work cable should not be considered a ground. It is not.
: Very true. I'm not sure if it's a good idea to ground the secondary winding of : your welder by grounding the work table. It would be better to follow the : recommendations of the manufacturer or if I may suggest, Gary Coffman here on : the NG.
In all of the manuals for my Miller machines they recommend grounding the table. If you are using HF, it is necessary to minimize RFI.
:>To ground your table (a good idea), you should run a ground wire to a water >or : gas pipe.
: Never never never to a gas pipe in the rare event something goes wrong. It is : bad enough to wire a ground to a "hot" water pipe. The Water Heater gaskets etc. : create spark gaps that will burn holes in the pipe instantly. I hate to think : what would happen if there were a spark gap somewhere in the gas pipe grounded : to a welder or power system.
OK, I agree, not to a gas pipe. You are correct and it makes sense.
Tom
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As long as we're both here to talk about it, I think we're doing ok. I do differ in my opinion though. We agree that the muscles react only once to DC but where we differ is I say they don't relax until the current stops or the muscle strength yields (death). In other words, yes they only contract once but are locked and all motion like heart beats and breathing stop. You may be right but I don't want to find out. I've been bit by AC plenty but never by DC. I always thought it was DC used in the electric chairs. The accounts I heard sounded like what I described as a single tensing up. No trembling.
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AC is used in electric chairs.
From personal experience, AC contracts and DC expands. I was stuck on 277 and COULD NOT let it go. I some how managed to drop myself from the top of a 7 foot ladder. The sound in your head from the AC is unbelievable ! AC travels through the bones and heats up from inside out. If you get locked up on AC then the meat on the insides gets "cooked" and the bones soften. Most external damage from AC is from arcing, the skin gets cauterized so you end up with nasty scars.
The problem with DC is that it travels in one direction and it can blow out where it connects. Say you have a wire in your hand and your elbow touches ground then DC can blow out the skin at the elbow because of resistance and heating and the direction that DC is traveling. DC tends to "throw" you, your muscles expand and extend the limbs. I grabbed a spark plug wire on a lawn mower when I was young to see if it had a spark , pulled the starter and was promptly thrown back from the mower and spark plug when the generator charged and my arm muscles extended.
These are only two of many personal experiences. I got the information about AC traveling through the bones from the emergency room doctor that attended me after I got the 277 volt shock and it makes sense as I only had a very small burn on my thumb and no other burns. You could squeeze my wrist bones together.
BTW, I was connected from hand to hand on the 277. Electricity traveled across my shoulders and even went up my neck. I had a hold of a piece of grounded metal flex in my left hand and the hot wire was only touching my right thumb, I could NOT let either of them go. My head was thrown back, my neck muscles constricted, my arms frozen in place gripping the flex stronger than I could normally and the noise was hideous. A really odd thing about it all was there was no pain, none. But it scares the hell out of you when you see black twice and no longer feel your body. I saved my life by unlocking my knees and dropping off the top of the ladder, I don't know how. I am my own hero for saving me my life. You will never be so terrified as when you get locked up on hot wires and can't let them go.
Yeesh! Looks like I need counseling or something<G>. Sorry to drift off with the life story. Turn the power off.
No1
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Thanks for the story No1. It just goes to show how much there is to learn on this NG!
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My experience differs from yours. I contacted a 285 volt DC bus in a WP33 power supply (very stiff supply) and could not let go. I had to break a regulator tube (killing the supply) with the screwdriver in my other hand to get free.
Electricity causes the muscles to contract, period. If the contraction jerks you away from the power source, well and good, but if it clamps you tighter to it, tough luck.
Unfortunately, when you grab something with your hand, the muscle contaction causes the hand to clamp down tighter. If you brush it with the back of your hand, the contraction draws the hand away from the power source. So it depends on how you contact the live power source whether you'll be clamped to it or knocked free.
BTW nothing forces a muscle to violently extend. It can only contract or relax. Muscles operate in pairs across the joints so that the contraction of one will extend the other, and vice versa. So if, for example, the current passes through the biceps, your arm will contract. If it passes through the triceps, your arm will extend. But it is always the contraction of a muscle which causes the movement.
Gary
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A typical stick welder has an open circuit voltage of 50 to 80 volts. (More is better for getting a quick arc start) So if you hold on to the bench and the electrode that you are inserting, you get the full OC voltage. Not pleasant, usually not damaging.
On the good side, the coating on many rods is non conductive, you wear gloves, and you don't touch the table so it is not normally a problem. For pipeline welders standing in 3 inches of water in a trench, it can get real nasty.
Mig welders have a relay that energizes everything when you pull the trigger. Otherwise it is cold.
FredBear wrote:

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Cheaper MIG welders used to save money by not having the relay and having a live torch. Worth checking if not sure.
Roy J wrote:

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99% (OK, I made that up, but it is pretty close) of pipeline welding is done on the bank, on skids, at the perfect height. Tie ins are made in the ditch. If the ditch has 3 " of water in it, the welder would have the hoe operator dig down to dry material, that's what the operator gets paid for. In the odd set of circumstances where a tie in just absolutely has to be made in adverse conditions, the welder will try to keep dry gloves on, stay on his mud board, or stop the job due to safety considerations.
JTMcC.

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I'd agree on the main pipeline construction although it wasn't always that nice. But the distribution pipe in town does not seem to have the nice working conditions when they tie in or have repairs. But all it takes is some damp conditions like a morning dew or mist to really change things. ( I was going to say 'Charge' things, sorry about that!)
JTMcC wrote:

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done
ditch.
operator
stay
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Yeah, I learned that the hardway. Back in my Green horn days.(27 years ago) I got myself in a BAD situation, because I did not make sure the situation WAS safe. (it's common sense to most, but I ran on a dumb philosophy in that day, "if there's a will, there's a way" LOL! I was a good little workin' goy, that did not question "authority" at the time, and did as was told. You wise up quickly, after you get bit good and hard, (if you live through it). I got an oppurtunity to "see" what welding current "Looks Like" from the inside, with all it's variuos harmonics and all. It even leaves a taste in your mouth, that stays for the rest of the day. LOL!
I get back to the shop, after completing the job, and this old timer takes one look at me and starts laughing his aXX off, and "says what the hell happened to you!?" I explained the events that transpired, he got serious, and I never forgot what he told me. He said, "There is never a job you HAVE to do, if the situation is not safe. You should have made the operator dig it out proper, and as soon as you saw the line was rotted, packed it up and came back to the shop."
The supervisor, and the rest of the crew (city/county) had left as sooon as I had the nipple welded on, and had the flange clocked/tacked, and saddle fitted/tacked in place. I was all alone down in the hole. I laugh about it now, and think to myself, what a dumb-axx! LOL! I found out later, the "officials" knew all about the condition of the line but it was hush-hush, as the city had collected money for replacement of this stretch of line years before, but spent it elsewhere. If you do not look out for yourself, and have the common sense to know when somebody is asking you to do something stupid, you'll be the "dead dumb goy" in the end. I mean when I cracked the crete off the line and saw all the moister, scale, and deep pitting, when chipped clean, I should have stopped right there, but I was a green horn, with a programmed "work ethic". These were only 14 ga. to start with. I had done 20 plus "hot taps" in better situations before landing this one. Ah, ......memories of youth and stupidity. <VBEG>
Kruppt
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No one I know of would work in 3" of water unless it was a

And
I've also got a picture of a friend of mine about 20' out in a lake, wearing fishing waders, in water almost up to his waist, welding a lookout on a 36" steel pipe pile. His leads were strung out on the bottom of the lake, I told him he was lucky to not get a citation for illegal fishing : )
JTMcC.
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"FredBear" <Fredbear2412(via)yahoo.com.au> wrote in message
...

Digital multimeters cost under $10 today and then you know.
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I don't worry about it, BUT I do make it a practise to follow a couple of safety practises all the time. One is not to touch conducting surfaces with both hands. Current from hand to hand goes thru the chest.
Second if there is any thought that you might get a shock, touch the object with the back of your hand. A shock makes you do things unvoluntarily. Like close your hand and grip the thing that is giving you the shock. These are just things I do without thinking. Good habits to get into.
But I never turn off a stick welder to change rods and I can't remember ever getting shocked. Before I start I put the additional rods so they can be picked up while wearing gloves, so most of the time I do it while wearing gloves. Not because I want to be wearing gloves when I do it, just so I don't have to take the gloves off and put them back on. And generally I don't weld in the rain. Just because I do all my welding for fun and it isn't as much fun in the rain.
Dan
"FredBear" <Fredbear2412(via)yahoo.com.au> wrote in message

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On 24 Nov 2003 10:39:44 -0800, snipped-for-privacy@krl.org (Dan Caster) wrote:

I learned that the hard way a lot of years ago, while setting up a pressurecassting machine, while the power was on. A nice 220 volts in one hand and out the other. Right through the gloves. Got stuck for a moment, but managed to jump free. Dont try that at home Now I always turn of the Mig before touching the tip. And mine is an old one where the tip is always live. Henning
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I am not a professional welder, or even much of an amateur, but I do know a couple of things about electricity, as do the rest you, also, judging by the postings I have read over the months. First--you all agree that the so-called "ground" cable is not a ground, and should not be thought of that way. It is the return conductor of the welding circuit. Second--when you weld on cars, you all agree that the return should be clamped very close to the area of the weld, to protect the car's electrical circuitry and any bearings from the heavy return current.
So, if you have to weld a pipe while standing in several inches of water or mud, I believe you would be safe if you followed the same precautions. Attach the return cable close to the weld, and make sure the ground water is not in the circuit.
Is there something I am missing?
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I also remember reading here about welders erecting sign posts or something similar in the rain, getting shocked and laughing it off. The gist of the story was to stay out of the circuit and you'll be fine. Don't earth ground the welder secondary.
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