0
$\begingroup$

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

enter image description here

enter image description here

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

Improve this question
$\endgroup$
1
  • $\begingroup$ Sorry i will downvote you because you ask a question about safety . All these things are well documented and you can find them on internet . Don't even try to deviate if you love your wife. $\endgroup$
    – Larsa se eidaklaxtarsa
    Sep 14, 2021 at 16:36

2 Answers 2

Reset to default
5
$\begingroup$

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)

enter image description here

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

enter image description here

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).

Improve this answer
$\endgroup$
3
$\begingroup$

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.

Improve this answer
$\endgroup$
3
  • $\begingroup$ It was purely academic, I didn't asked it as pre real life testing stage but was just curious how it would went out and how much of current normally going through human body could be "redirected" to wire attached somewhere to humans body and also that's why I used strap as example of concept and mentioned thicker wire but it seems that everybody seems to be concerned about safety. In my head question was more "what if we could make perfectly conducting anti static wrist wrap with thick wires and perfect contact pad - maybe it would help remove majority of current or maybe totally stupid idea?" $\endgroup$
    – bestestefan
    Sep 14, 2021 at 19:33
  • $\begingroup$ No, as I mentioned this hypothetical device would actually make the situation much worse. You want stray current to be guided to ground away from a person, which is what a grounding wire does. A wrist strap is better to think of as a drain for charge, not voltage (although they are related). In fact, you also want the circuit board you are working on to be grounded as well to dissipate its charge. It's the charge jumping from one thing to another that causes damage. $\endgroup$
    – RC_23
    Sep 15, 2021 at 5:53
  • $\begingroup$ Your picture reminded me a bit of the Faraday suits that workers sometimes wear when servicing high voltage electronical lines. It's basically a metal mesh full body suit, like medieval chain mail. It's purpose is to give any arcs a path around the body, so none of the current passes through the body. But a grounding wire on your wrist would not accomplish this. $\endgroup$
    – RC_23
    Sep 16, 2021 at 1:26

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.