Newbie question trying to understand electricity

[gthomson]

I'm new to welding based on electricity.
Did oxy/acetalyene 40 years ago for a class in high school.
Now taking a class on welding for MIG, TIG, etc...


In the first hands-on class last week, one guy seemed to have a good technique for MIG welding, and teacher mentioned that also.


Hard to get a good picture of his technique with only two hands, though.
It was something like the pic below - left hand going across to the right.
And then his right hand rode across it from left to right with the MIG tip.


I thought he'd be electrocuted because he was touching the metal that was grounded, and also on the other end with the MIG torch.


Are these the reasons he wasn't electrocuted?
On the left arm, he had a thick glove, so that kept it from being conductive from the grounded metal table to him?
On the right, holding the MIG torch, just pressing the MIG torch button activates the wire feed, but it's not a piece involved in the conductivity side of things - it's insulated from that.


So I'm now wondering 'how can I be electrocuted while MIG welding?' - I'd like to avoid that.
Better question is maybe 'how do I not get electrocuted while MIG welding?'
Have you ever known somebody that got electrocuted while MIG welding, and how did it happen?
Or is it something so rare that it's not something to really think of as a problem that might happen?

[scsmith42]

The human body has a natural resistance up to around 50 volts. Above that voltage most folks can feel it, below it they don’t unless their hands are wet.

Most MIG welding is performed at less than 30 volts, so you are not in danger of being shocked.

[G-ManBart]

There's actually a lot going on here, but the short version is it's not too likely you can electrocute yourself MIG welding.

I'll probably get jumped on for this comment, but situations like this are why I dislike when people call the work clamp a "ground" clamp...it muddies the water. You said the work piece was grounded, and I'm assuming you mean it had the work cable/clamp on it. That isn't ground, although the work could have been grounded if it was in contact with a metal table that was actually grounded. The work clamp is simply the negative line in the circuit (in this case). Current is supposed to be flowing through both the torch and the work cable where current isn't supposed to be flowing through a ground. As far as why you won't get electrocuted even while touching the work, it's because electricity follows the path of least resistance, and human bodies have high resistance in comparison to a copper cable like the torch/whip/wire and the work cable.

I have read about welding electrocution deaths, but it's usually stick welding while laying in water/wet ground and using leads that are cracked...that sort of thing.

[M J D]

I can't think of one time Ive gotten zapped mig welding. A few times with wet gloves stick welding with DC current. More times than I care to remember stick welding with AC current.

[12V71]

I can't think of one time Ive gotten zapped mig welding. A few times with wet gloves stick welding with DC current. More times than I care to remember stick welding with AC current.

I've done it holding a part to be tacked on to an existing structure without gloves and hitting the part I was holding by hand with the wire. I don't do that anymore...

[Oscar]

The MIG "tip" is actually a nozzle (the tip is inside where the wire actually comes out). The nozzle is not electrically hot ever unless the system is physically compromised from the start. Sames goes for the neck of the MIG gun. It is insulated from the actual current-carrying components within it.

[Jack Ryan]

Electric current flows in a loop – positive to negative, active to neutral. To receive an electric shock, or to be electrocuted, you must form part of that loop. In addition, the voltage must high enough to overcome the resistance of your body and the source must be able to supply enough current to do damage.

To be in the loop, you must be touching the work and the electrode (the wire for GMAW/FCAW). This is possible but unlikely and would generally require the arc to extinguish to pose a threat.

Welding voltage is generally too low to cause a threat, but the open circuit voltage might be high enough. Modern welders usually limit the open circuit voltage as a safety measure.

Some welders and plasma cutters use “HF start”. This voltage is quite high (10-15kV) but the supply current is very low so there is a very, very low chance of electrocution. People with pacemakers would be advised not to purposely generate sparks from the electrode to the finger and there is a small chance of receiving a RF burn.

I think that overall, there is a very small chance of being electrocuted and it you make sure that your equipment is in good order and use common sense, that chance would approach zero.

Jack

[farmersammm]

The workpiece is only "grounded" when your sweaty arm is on it, and yer feet are in a puddle, or wet ground

[gregket1]

A gross oversimplification but the easy way to understand all electrical flow is this: Electricity is lazy, it will take the easiest path to get where it needs to go to complete the circuit.

Since it is easier for electricity to flow through metal than through humans, we are generally safe. I’ve seen many people holding the stick-electrodes with their hand while welding.

If you keep You on the opposite side of the electrode from the clamp, you are safe because the electricity is flowing away from you. Ask the deep sea welders how important this is.

If you forget to attach the clamp and your body is the only path for the electricity to get from one electrode to the other, you are toast. Depending on voltage and amperage, possibly literally.


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[Kelvin]

Electric current flows in a loop – positive to negative...

What are you, Benjamin Frankiln, or just British? Or a time traveler?

(For our purposes, in 21st-century USA, electrons -- with a negative charge -- flow from the negative pole to the positive pole ... and this info can come in handy when you're learning about DC tig, but also all DC welding...)

I wouldn't worry too much about getting shocked or electrocuted. Wear dry gloves and wear shoes when you're welding, and don't be the only path for the electrons to follow, for example by clamping the stinger on your tongue and the work clamp on your ... toe. Beware of when you're welding in sweat-soaked clothes. Use common sense. You'll be fine. And be especially careful if welding with AC current, as the 60Hz oscillation can put your heart into fibrillation...AC welding current is a bit more hazardous than DC, or so they say.

As for stick welding, it's the bare tip of the stick you want to be careful of. The flux coating on the stick has insulating qualities...and if you stop welding halfway through a stick of 7018 and some other electrode types, the flux will have melted into an insulating blob of glass on the end of the stick that you will have to break or file off to get the current flowing again...

Just get into the habit now of only welding with dry gloves on. This will also help protect you from burns. (Sunburn is also an issue with arc welding.) And welcome to the forum!

[William McCormick]

Electric current flows in a loop – positive to negative, active to neutral. To receive an electric shock, or to be electrocuted, you must form part of that loop. In addition, the voltage must high enough to overcome the resistance of your body and the source must be able to supply enough current to do damage.

To be in the loop, you must be touching the work and the electrode (the wire for GMAW/FCAW). This is possible but unlikely and would generally require the arc to extinguish to pose a threat.

Welding voltage is generally too low to cause a threat, but the open circuit voltage might be high enough. Modern welders usually limit the open circuit voltage as a safety measure.

Some welders and plasma cutters use “HF start”. This voltage is quite high (10-15kV) but the supply current is very low so there is a very, very low chance of electrocution. People with pacemakers would be advised not to purposely generate sparks from the electrode to the finger and there is a small chance of receiving a RF burn.

I think that overall, there is a very small chance of being electrocuted and it you make sure that your equipment is in good order and use common sense, that chance would approach zero.

Jack

Thanks to the jack arses in universities that thought it would be better to hide Benjamin Franklin's amazing work on electricity and open-air transistors, they changed the way Benjamin Franklin labeled electricity. So that now electricity does not flow from the (+) to the (-) but rather the opposite. Today the particles of electricity the electromotive force and pressure leave the (-) terminal and flow to the (+) terminal.

The ARC rod in reverse polarity beams a cathode ray back to the workpiece, which made many people think that is how the current flowed, however that is not true at all. Benjamin Franklin figured that out almost 300 years ago, with his pointed and flat electrode test. He had a grounded rod driven into the floor of his basement with a wire from it to a fireplace ball he had on a wooden table. He had another wire from his hillside home's roof to the basement and another fireplace ball on the same table. When a storm cloud approached it would send a current that would jump from one ball to the other. He had a few accidents where the ball attached to the copper wire on the roof jumped to a wire and he was badly burned. So he did some experiments using a pointed and flat electrode. When he attached the pointed electrode to the roof and a flat plate electrode to the grounded rod in the floor, it would create a loud bang but leave the pointed electrode rather intact. When he reversed the electrodes he burned his hands and face very badly as the pointed electrode melted and hit him with a cathode ray.

After World War Two they decided that the citizens of the earth should not understand a bomb, electricity, or basic science. They openly announced that they would hide the secret of the atom from the citizens of the earth which leaves me with the question if they are not citizens who are they? Goerge Washington wrote, "When we assume the role of the soldier we do not give up the citizen." So I am a bit confused. In any event, the terms of electricity today are a hot mess. The positive terminal would be a terminal with an abundance of particles of electricity. Particles of electricity repel all other particles of electricity and matter there is nothing negative about them. There is no such particle as a neutron which should give you an idea of how screwed up "physicists" are and how screwed up the "universities" they learned and teach from are.

After World War Two welding companies refused to put (+) or (-) on welding machines because it was a lie. They used Straight Polarity and Reverse Polarity instead. Straight polarity meant the electricity came from the electrode to the workpiece. Reverse polarity meant the power went from the workpiece to the electrode and the electrode reciprocated with a cathode ray against the flow of the power supply.

Sincerely,

William McCormick

[William McCormick]

What are you, Benjamin Frankiln, or just British? Or a time traveler?

(For our purposes, in 21st-century USA, electrons -- with a negative charge -- flow from the negative pole to the positive pole ... and this info can come in handy when you're learning about DC tig, but also all DC welding...)

I wouldn't worry too much about getting shocked or electrocuted. Wear dry gloves and wear shoes when you're welding, and don't be the only path for the electrons to follow, for example by clamping the stinger on your tongue and the work clamp on your ... toe. Beware of when you're welding in sweat-soaked clothes. Use common sense. You'll be fine. And be especially careful if welding with AC current, as the 60Hz oscillation can put your heart into fibrillation...AC welding current is a bit more hazardous than DC, or so they say.

As for stick welding, it's the bare tip of the stick you want to be careful of. The flux coating on the stick has insulating qualities...and if you stop welding halfway through a stick of 7018 and some other electrode types, the flux will have melted into an insulating blob of glass on the end of the stick that you will have to break or file off to get the current flowing again...

Just get into the habit now of only welding with dry gloves on. This will also help protect you from burns. (Sunburn is also an issue with arc welding.) And welcome to the forum!

If you are sweating laying on your back welding the underside of the handicap railing horizontal in the summer, and you touch the flux coated welding rod with your sweaty glove or bare hand you will feel it. It does not seem to kill you but you know you are passing current. Dry gloves in the railing and fencing industry are a myth. When it gets really bad or I have a broken rod holder I buy a pair of women's latex gloves and put them under the damp or wet leather gloves, that seems to stop everything.

But you can die well connected to the ground, or barely connected to the ground.

Sincerely,

William McCormick

[Denis G]

Google "Conduction of Electrical Current to and Through the Human Body: A Review" .
Here's a link to the article: https://www.ncbi.nlm.nih.gov/pmc/art...lasty09e44.pdf

There are many more ways to kill yourself with welding. Fuel tank and pressure vessel repair come to mind.

[milomilo]

I've done it holding a part to be tacked on to an existing structure without gloves and hitting the part I was holding by hand with the wire. I don't do that anymore...

Been there done that.. Kinda like peeing on an electric fence wire. Only takes once to decide not to do that again!!!!

[Jack Ryan]

What are you, Benjamin Frankiln, or just British? Or a time traveler?

(For our purposes, in 21st-century USA, electrons -- with a negative charge -- flow from the negative pole to the positive pole ... and this info can come in handy when you're learning about DC tig, but also all DC welding...)

Conventional current, that used to teach the subject, flows from positive to negative.

Most people also know that electrons and negative ions flow from negative to positive and that positrons and positive ions flow from positive to negative. In a plasma (like an arc), there are both positive (ions) and negative (electrons) particles.

I was not concerned about the particles that made up the current, their charge or the direction in which they travelled, so I used the abstract form - conventional current - which flows from positive to negative.

Jack

[Willie B]

Electric current flows in a loop – positive to negative, active to neutral. To receive an electric shock, or to be electrocuted, you must form part of that loop. In addition, the voltage must high enough to overcome the resistance of your body and the source must be able to supply enough current to do damage.

To be in the loop, you must be touching the work and the electrode (the wire for GMAW/FCAW). This is possible but unlikely and would generally require the arc to extinguish to pose a threat.

Welding voltage is generally too low to cause a threat, but the open circuit voltage might be high enough. Modern welders usually limit the open circuit voltage as a safety measure.

Some welders and plasma cutters use “HF start”. This voltage is quite high (10-15kV) but the supply current is very low so there is a very, very low chance of electrocution. People with pacemakers would be advised not to purposely generate sparks from the electrode to the finger and there is a small chance of receiving a RF burn.

I think that overall, there is a very small chance of being electrocuted and it you make sure that your equipment is in good order and use common sense, that chance would approach zero.

Jack

You are almost correct. Electrons (negatively charged) flow to positive.

[Willie B]

Welders are limited in voltage. Old transformer based welders might have up to 100 volts. It is enough to give you a thrill!
Newer machines may have a much lower Open Current Voltage.

Shock happens when you place yourself between the two leads of the welder. It rarely happens when an active arc is present.

In youth I frequently stick welded on wet ground in sneakers, also wet. A big weldment sitting on wet ground is contiguous with the work lead. Touching the stinger with wet gloves completed the circuit, work lead to workpiece. workpiece to earth, earth to wet sneakers, sneakers to feet, feet are part of body. From body to gloves (wet) & back through stinger to welder completing the circuit. I don't like it, but despite the shocks, I'm still perfect.

MIG reduces the likelihood you'll touch a live object. Also reduces risk of shock.

TIG is another matter. It'll bite you now & again. You'll very likely survive.

[Slowxj]

Haven't been bitten by mig or sick yet... even used both in steady drizzling rain due to necessity...
High frequency tig bit me once though... it smarted lol

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[Jack Ryan]

You are almost correct. Electrons (negatively charged) flow to positive.

That is precisely what I wrote in my last post:

Most people also know that electrons and negative ions flow from negative to positive

and I made no mention of electrons in the post before that.

Jack

[William McCormick]

Conventional current, that used to teach the subject, flows from positive to negative.

Most people also know that electrons and negative ions flow from negative to positive and that positrons and positive ions flow from positive to negative. In a plasma (like an arc), there are both positive (ions) and negative (electrons) particles.

I was not concerned about the particles that made up the current, their charge or the direction in which they travelled, so I used the abstract form - conventional current - which flows from positive to negative.

Jack

Everyone doesn't know that positrons flow from the (+) terminal to the (-) terminal because they do not. There are no such things as positrons. That was the French scientist Du Fay's theory that was enforced by England three hundred years ago. England did not want the English citizen to understand electricity or much of anything else. Benjamin Franklin's tests, the lightning rod, and flying a kite in an electrical storm did away with Du Fay's wacky theories. Only the wacky universities of today could have brought Du Fay's work to life once again like a Frankenstein monster. When you see a cathode ray you are watching particles of electricity leave a terminal that is short of particles of electricity, beaming back against the abundance of particles of electricity from the power supply. That is what Benjamin Franklin figured out almost three hundred years ago with some copper wire and some iron electrodes. But the universities have clouded his work to a point that they themselves are not fit to handle electricity. They often claim you cannot fly a kite in an electrical storm, when of course if you understand electricity, you can. People do not have the stomach for what is in charge and what children have been fed as truth in "school". The reason for all the confusion is if you can understand a cathode ray you know how to make atomic weapons in your garage without radioactive materials. The counterintelligence was openly announced after World War Two, many did not know what the government planned to do when they said they would hide the secret of the atom from the citizens of earth or we would not be having this conversation.

The molten surface of an electrode being struck by an abundance of particles of electricity creates an area so high in voltage that it is capable of detonating many common materials. You can use a tiny ARC on the surface of mercury for the purpose of detonating rather difficult to detonate substances. It is that initiating explosive voltage created by the cathode ray that beams back to the workpiece against the flow of an abundance of particles of electricity from the welding machine's power supply from an ARC rod. Just like the molten surface of the cloud when struck with enough electricity from the surface of the earth will reciprocate with a lightning bolt. There is no voltage that could travel through the air in our atmosphere to the earth that could carry lightning voltage. But the high voltage on the surface of the cloud being of explosive initiation voltage can cause air molecules to expand to a point they create a near-vacuum that will carry that voltage and current in a zig zap pattern to earth. That zig-zag pattern is the key to understanding the difference between the loop and initiating explosive voltage that is not in a loop and is created by slowing ambient radiation. Loop voltage travels in a straight path from A to B, an ARC (Anode, Rectified, Cathode) travels in a non-straight path because it is not a point A to point B communication. It is explosive voltage looking to go anywhere of less voltage. The loop voltage only travels from point A to point B in the shortest distance possible. That is how Benjamin Franklin steered the lightning away from homes because he understood the ARC that is only looking for a place of less voltage.






Sincerely,

William McCormick

[William McCormick]

Duplicate post

[Jack Ryan]

Everyone doesn't know...

I'm sorry but I'll have to bail at this point as I forgot my tin hat.

Apologies to the original poster but you should not be overly concerned about electrocution as long as common sense prevails.

Jack

[William McCormick]

I'm sorry but I'll have to bail at this point as I forgot my tin hat.

Apologies to the original poster but you should not be overly concerned about electrocution as long as common sense prevails.

Jack

You chose a very small sentence fragment from my post that does not confront the subject of my post at all. I also disagree with your observation that you forgot your tin hat, I think if you look in the mirror you will see it is sitting squarely on your head.

I started welding when I was 9 and I welded for over twenty years doing things I hope others never have to do. I thought I pretty much had seen it all, until one day I fell back on my heels while welding and the same effect that I had experienced a hundred times before without any damage to myself suddenly stopped my heart. It took me six months before I could walk upstairs without being winded. In that time I researched what had happened to me. And I found it was capacitance. The surface area of your feet in contact with the ground or your butt with a chair determines how electricity will flow or not flow through your body. I have done testing so I understand it. I would also say it is rare that someone will experience this same accident however it can happen I know.


Sincerely,

William McCormick

[Kelvin]

So...I guess if positive particles (as well as negative particles) travel in a plasma stream, then "cold" travels the same way as "heat travels."

So I guess that means the "cold" moves from the workpiece (and the electrode) into the welder. What happens when the cold particles accumulate in the welder? Do you have to empty them out from time to time?

I guess this is why SA-200 welders slow down after they've been used too long continuously ... too much cold buildup!

[Louie1961]

You will only receive a shock from welding current if you place yourself in the circuit between the work lead and the electrode. I have never been shocked by MIG. I have been shocked once while stick welding because of a crack in an electrode holder which let me touch the bare metal underneath. I have been shocked a bunch by my old TIG welder, mostly from the high frequency starting circuit and wet gloves. AC current is more dangerous than DC current. MIG welders are some of the safest welders because they use DC current and low voltages, and are only energized while the trigger is pulled. All of this refers to secondary shock from welding current and not a primary shock from electrical service from the wall.