Can grounding wrist prevent electrical shock?

Question

Today while repairing some electronics and wearing anti-static wristband like on picture below I got thinking - in theory, would it be possible to avoid shock while working on mains by grounding yourself using such antistatic wristband / some copper wire wrapped around your wrist?

In theory I think such band / wire should give less resistance than body to ground and it should make electrical current go through it to ground rather than through whole body to feet, but maybe I'm wrong? Also I know that anti-static wristband probably wouldn't be suitable for higher voltages / currents but it's used as proof of concept, below I also sketched what I'm talking about to clarify

yellow = mains voltage e.g. 230v AC

brown = ground

green = grounding wire running from wrist to ground

black = test specimen

We assume that in both cases on the left and right test specimen is touching ground with his both feet even though on picture it doesn't look like it and that wire is making perfect contact with his wrist and ground, and "prevent shock" means that electrical shock effects would be slightly reduced and current flowing through whole body would be much smaller

Answer 1

DO NOT WORK ON ELECTRICAL MAINS UNLESS YOU ARE A PROPERLY TRAINED AND LICENSED ELECTRICIAN

Seriously, this stuff can kill or maim you invisibly, without warning, and far faster than you can react to protect yourself. Don’t do it.

Here is an image of a "good" electrical injury (real electrical injury)

Here is an image of a "bad" electrical injury (not really, but you get the idea)

That said, the grounding wire is not designed to protect the wearer, it is designed to protect the electronic equipment that the wearer is handling. As you know, humans can frequently build up static electricity. When discharged suddenly this produces a small amount of current at a fairly high voltage.

To prevent such small-current high-voltage discharges from damaging electronics a grounding strap can be used. The grounding strap is a small wire, so it handles only small currents, but it prevents static from building up while connected.

On a mains the concerns are completely reversed. We want to protect the human from the mains, not vice versa. Furthermore, mains voltages are modest (far lower than static discharge voltages) and the big problem is the high currents that can be supplied. As such, the solution for electronics-protection will not work for human-protection on the mains.

Those straps actually have a modestly high resistance, so even in the best case scenario a substantial amount of current will go through the body. Furthermore, because they are so flimsy they will melt quickly and stop any minor protection. Finally, whatever tissue is between the point of contact and the grounding strap will still be injured even if the above two problems are solved through modifications of the strap. If the strap is on the left hand and the mains was contacted by the right hand then that path includes the heart (see the second picture above).

Answer 2

No, it will not protect you and might even put you in greater danger. A grounding strap or wire provides a path from the high voltage source to ground that passes through your body. That's the opposite of what you want for safety. The grounding wire in an outlet or appliance provides a path to ground from the metal housing, directing any current AWAY from the user.

The reason grounding straps are used is to siphon away any charge or voltage that builds up on the person, so they do not become the high voltage source that ruins an electronic part. It's a totally different situation and hazard being prevented.

I echo the stern safety warning of the previous reply – if you have to ask this question, you are NOT even remotely qualified to work on electrical equipment. Hopefully this was just an academic question.