Mains electricity - shocks

Orion21

Orion21

Orion21

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Joined
20 Feb 2006
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343
Physics was never my strong point but I just got to wondering about mains electricity and electric shocks / electrocution.

If for example you unplugged a TV power cable from the TV but left the power socket switched on could you get a dangerous electric shock from the end of the cable?

Essentially I am wondering where the current / voltage drawn on the plug is determined, is it in the appliance itself or at the plug for the appliance? As I am aware it is the combination of these that matters in terms of getting electrocuted.

Or do all plugs draw the same level of current / voltage when unplugged from an appliance but plugged into and switched on at the mains?
 
What?

Are you asking if you have a power lead plugged into a plug socket, but with nothing attached on the end, does it draw any current?
 
If you close the circuit on the mains, with your meat as the conductor, it will give you all the currents that will fit in you. Not pleasant, don't try it.
 
The current drawn from the mains depends on the resistance of the appliance connected, given that the voltage is constant.

You're not going to get a lethal shock from the mains because the RCD in your consumer unit will trip. So all you'll get is a brief shock.
 
If the power cable is a kettle lead style, then there is no draw, as there's no complete circuit if its not plugged in to anything at the end.

If you stick a screwdriver in the live, then yes you'll get a shock.
 
Sliver said:
You're not going to get a lethal shock from the mains because the RCD in your consumer unit will trip. So all you'll get is a brief shock.
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Assuming you have RCDs...

On the other hand you could have an old fused unit with ridiculously overspecced wire or possibly a nail acting as a fuse and you WILL NOT trip that out.
 
Your resistance to the current also depends on how wet you are.

As the power is directly proportional (with regards to current) to that, you want to be as dry as possible.
 
Sliver said:
Well that goes without saying. I was assuming his property was in accordance with current regulations.
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Assume nothing, I thought better to be clear rather than read about some poor guy in tomorrows paper that was turned into a charcoal briquette whilst uplugging his tv with his his tongue.:D
 
Dunks said:
What?

Are you asking if you have a power lead plugged into a plug socket, but with nothing attached on the end, does it draw any current?
Click to expand...

No I am asking if I somehow managed to make contact with the end of a cable if I unplugged it from an appliance (e.g. TV) what current / voltage would I be hit with when completing the circuit?

I ask as I thought that phone chargers etc generally converted this down to a lower current / voltage before the end of the wire so would likely be at less risk.

I'm just curious and this isn't something that is my strong point although I wouldn't pull out the power lead from an appliance without switching it off first as it isn't worth the risk with electricity unless you know what you're doing for sure. I may however pull out the plug without switching it off if it's on an extension cable but the UK insulated plugs should make this safe enough to my understanding.
 
Orion21 said:
No I am asking if I somehow managed to make contact with the end of a cable if I unplugged it from an appliance (e.g. TV) what current / voltage would I be hit with when completing the circuit?
Click to expand...

You'd be hit with 230 volts and the current would depend on your body's resistance. Like I said earlier though, assuming your property is line with current regs, the RCD would trip in milliseconds so all you'd experience is a brief shock.
 
If you have a device with a rubbish power supply which has no bleed resistance to discharge any capacitors when you unplug the device then you may be able to discharge any residual current through yourself if you touch the live + neutral together (I have had this happen to me before on some ancient bodged test gear) didn't really hurt too much.

Nowhere near as bad as when I was an apprentice and we used to zap each other with the 1000V insulation resistance test gear :)
 
Sliver said:
You'd be hit with 230 volts and the current would depend on your body's resistance. Like I said earlier though, assuming your property is line with current regs, the RCD would trip in milliseconds so all you'd experience is a brief shock.
Click to expand...

Thanks that makes sense, I guess the difference is that the chargers would have a transformer before the end on the cable that would reduce the current / votes, whereas that reducing is done in the actually appliance for most things.
 
I've been electrocuted 3 times by 240 mains, twice on CRT TVs (as a kid tinkering) and once on a PSU. It's not nice and hurts :D

I've been electrocuted a few times by 110V on site too but this is fairly mild tbh.
 
jsmoke said:
If you were suspended in air and touched the live would you still be shocked, would air particles complete the circuit?
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No as the circuit wouldn't be complete, air acts like an insulator at low voltages such as the mains. However if you bridged the circuit by touching both the live and neutral or earth, then you'd get a belt.
 
Sliver said:
You're not going to get a lethal shock from the mains because the RCD in your consumer unit will trip. So all you'll get is a brief shock.
Click to expand...

Video evidence of you licking a power supply lead needed as proof or I'm calling BS!
 
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