Newbie question trying to understand electricity

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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?


Reply: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.Miller Trailblazer Pro 350DMiller Suitcase MIGMiller Spectrum 2050Miller Syncrowave 250DXLincoln 210MP
Reply: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.Check out my bench vise website:  http://mivise.comMiller Syncrowave 250DXMillermatic 350P with XR AlumaProMiller Regency 200 with 22A feeder and Spoolmatic 3Hobart Champion EliteEverlast PowerTig 210EXT
Reply: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.
Reply:

Originally Posted by 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.
Reply: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.

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Reply: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
Reply:

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


Reply: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. Sent from my iPad using Tapatalk
Reply:

Originally Posted by Jack Ryan

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

Originally Posted by 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
Reply:

Originally Posted by Kelvin

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!
Reply: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.pdfThere are many more ways to kill yourself with welding.  Fuel tank and pressure vessel repair come to mind.
Reply:

Originally Posted by 12V71

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...


Reply:

Originally Posted by Kelvin

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...)
Reply:

Originally Posted by 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
Reply: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.An optimist is usually wrong, and when the unexpected happens is unprepared. A pessimist is usually right, when wrong, is delighted, and well prepared.
Reply: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 lolSent from my SM-A426U using Tapatalk
Reply:

Originally Posted by Willie B

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

Originally Posted by Jack Ryan

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
Reply:Duplicate postIf I wasn't so.....crazy, I wouldn't try to act normal, and you would be afraid.
Reply:

Originally Posted by William McCormick

Everyone doesn't know...