Welding and risk of electric shock

Question

I would like to learn to weld (stick welding) for my own purposes (mostly for small repairs and building simple metal constructions). So far I'm trying to educate myself by reading and watching instructional videos, but so far I haven't found an answer to one question which is bothering me (I know it may sound stupid):

Assuming that welding equipment is fully functional (free of any defects and everything is set up properly), is there a risk of electric shock if a welder inadvertently touch part of construction which he is welding?

Answer 1

No. Current will always take the path of least resistance. The path of least resistance is through the ground clamp that you secure to the workpiece, or another conductor that the workpiece is touching. If this ground clamp becomes disconnected, you can't weld (or start to), because the circuit would be broken.

If you're welding in wet conditions or providing a path to ground (i.e. holding the ground clamp and touching the electrode) then there is certainly a risk of electrocution.

You should always make efforts to provide the safest possible path to ground though, do not clamp to oxidised/painted metal and do not weld in wet conditions. The main risks involved in welding are more concerned with burns, corneal inflamamtion and retinal burning from the UV generated by the arc.

Answer 2

As long as the equipment isn't faulty and you don't do anything really silly you are very unlikely to get electrocuted from stick welding simply because the voltages involved are not large enough.

Indeed in most welding processes it is fairly normal to be touching the work at some point during welding, albeit you are usually wearing gloves.

While it isn't impossible to get a shock from stick welding and of course you need to be aware of general electrical safety it's not an immediate hazard that you need to actively avoid, in the way that burning yourself on the hot metal is.

When you absolutely can get a shock is TIG welding with a machine with high frequency start. If the work isn't well earthed and you're touching it you will get an unpleasant shock as the high frequency element superimposed on the current is much better at being conducted through the human body than the main DC or low frequency AC current.

Answer 3

I am a welder, and here to tell you, you can definitely get shocked. True, if everything is in good condition, proper PPE you are golden. This means your ground has good connection (the bolt holding the wire to the clamp is tight, strong spring for clamp, clean surface on base metal in contact with the ground clamp, not going through any moving parts i.e. bearings, swivels), wearing gloves and good thick soled shoes, the more you sweat the higher chance you have, being engineers you understand salt water is a great conductor I am sure. High Frequency increases your chance to get a pants wetting experience (never happened to me but have seen guys pee themselves while TIGing).

Which is really why I am scouring the web to understand more about why HF will reach out and get ya. I get that's what it's for in welding, the electrical arc will reach out to the base metal instead of touching the electrode (tungsten) resulting in a contamination, but how does it?

Back to it though, some reasons for getting shocked.

1. bad ground of course
2. filings inside the welder from grinding (make sure you blow it out every 6 months or so) Best is to always unplug and take off the housing.

3. being wet (sweat, standing in water, early morning dew soaked gloves, ect.) making yourself a better conductor than the copper wire ground. This goes for other people around you. Early in my career I almost killed a guy (stick welding) on the other end of a project (around 20' away) because he was standing in water with soaked shoes touching it with bare hands.

   My advice is to never count on perfect conditions and always act like the gun is loaded, so to speak.

   There are many other hazards to welding but this should answer your question on getting shocked and how to best avoid it.

                 (source for the lower portion)
   

   https://www.brighthubengineering.com/power-plants/89792-ac-and-dc-shock-comparison/

   AC current is alternating in nature and follows a sine curve. It is continuously changing direction and passing through zero to a maximum positive value and then to a maximum negative value. The voltage of an AC current is a RMS or root mean square value, and the peak or maximum value is 1.4 times the RMS value. However DC current will make a single continuous contraction of the muscles compared to AC current, which will make a series of contractions depending on the frequency it is supplied at. In terms of fatalities, both kill but more milliamps are required of DC current than AC current at the same voltage.

Answer 4

Unlike TIG and MIG, stick welding does carry some risk of electric shock for the following reasons:

• There is no trigger switch on a stick welder, rather there is always a voltage between the electrode and the ground clamp.
• You need to touch the (consumable) electrode of a stick welder in order to replace it.

Therefore, you can give yourself an electric shock if you are replacing the electrode without turning off the welder, and you make skin contact with the grounded workpiece, or anything electrically connected to it. Perhaps the most likely scenario would be if the workpiece was on a metal workbench, you were wearing thin clothing or pants and a shirt rather than coveralls, and your hip brushed against the workbench while you were replacing the electrode. This risk can easily be avoided.

It is worth noting that stick welder voltages are lower than mains voltage (perhaps reaching only 80-100V), and are usually DC (unless welding aluminium), so the risk of death or injury is much lower than a mains voltage electric shock.

Touching the workpiece does not present a risk of electric shock unless you are also touching the electrode, and vice-versa. Like all forms of welding though, you can burn yourself due to the object still being hot.

Additionally, welding involves far greater risks than electrocution, such as eye damage from UV light (avoidable by using a welding hood), exposure to hazardous fumes (avoidable through extraction and/or respirator use), and burns due to UV exposure or direct heat (avoidable though use of gloves and coveralls), and the potential for starting fires (avoidable by removing all flammable materials from the vicinity).

Answer 5

To get shocked, the voltage applied to your skin (by touching an electrode) must be large enough to establish a current in your skin from the point of contact to the ground connection (usually your feet in contact with the ground).

At the voltages used for welding (just a few volts) this doesn't happen: at a potential of a couple of volts, your skin is a good enough insulator to prevent a current from flowing which is big enough for you to sense as a shock. Similarly, if you grabbed the two terminals of a 12-volt battery with your hands, the 12 volts isn't enough to force a current into your skin, up one arm, across your chest, and down the other arm. 120 volts will do the trick however!