BuzzLand said:
Yes but the point is that because it's AC voltage, once it's stepped down there's even less 'max current'
Having working on enough household electrics jobs when DIYing to say the following.
The worst I've ever had is a jolt here and there off mains voltage I can tell you a shocked hand and wrist is nothing to write home about.

Stop scaremongering and listen instead of towing the tired exaggeration monkeys. :)
Click to expand...

That max current is more than enough to kill a person. For example, take the average power shower, which operates at about 9kW. Its operating current at 230V will be around 40A. Your telling me that an AC supply, which can clearly supply that amount of current, cant produce a current which is able to kill a person?

This whole, "my friend bob" word of mouth advice can sometimes be very dangerous, this sort of discussion needs to be based on scientific fact, not somebody's opinion. You can call it scaremongering if you like, but I know anyone with any common sense won't try it.
 
What your not taking into account is the insulating properties of the shoes,carpet,floorboards your on to ground the house can act like a Faraday cage and is an equipotential zone.

When you realise that the ground is in fact a neutral return path to sub station, the only thing that affects it are the resistance of line conductor, resistance of person and resistance of ground return path.
 
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It's irrelevant whether the person is grounded or not, if you touch the live a neutral pins in a socket, you provide a dead short, hence the electrocution. I agree however, that if you wire a land rover to mains, and touched the body of the vehicle, the amount of current that you would conduct would depend on how good a route to earth your body provides, which is determined by the insulating properties of your shoes etc.

I'm simply disputing the statement that a mains supply is incapable of killing a person, and disagreeing with the flippant attitude towards it.
 
jamesmartin said:
i allways thought ac was safer as it would repulse you after shocking you whereas dc would hold you
Click to expand...

nope, ac can make you grab on and fry... that's why firemen always go into buildings with their backs of their hands in front - if they hit a power cable and it causes the muscle to clench, it will clench thin air and not a power cable
 
'You talk about AC having less amperage: "fck all Amps compared to DC and can be transmitted over longer distances as 10,000+ volts and require's less insulation". It's transmitted over large distances, using a step up transformer which massively increases the voltage across the Tx lines whilst reducing current. This reduces resistance across the lines, thereby reducing inherent power losses through heat which would be generated otherwise. This voltage is stepped down however before it is used in our homes, and the max current available is far greater, and certainly enough to kill. '

the bold bit is worng, because the current is stepped down this reduces the heating effect as P= I squared x resistance, the resistance of the wire stays the same but because the current (i) has reduced the heating effect reduces dramatically as why it is used in overhead wires which range from 32000 volts to 400000 volts.

i do agree that ac can kill but from experience i also know that it doesnt always, as i have been schocked myself and you can release under ac current as it spasams your muscles wheras dc locks them tight all of them hence dc is more dangerous. it also matters where the shock comes from as almost all appliances run on dc current and so you may survive a shock from a socket as it is ac but if it has gone through a dc inverter thenm your chances radically decrease.
 
200tdi ayre said:
'You talk about AC having less amperage: "fck all Amps compared to DC and can be transmitted over longer distances as 10,000+ volts and require's less insulation". It's transmitted over large distances, using a step up transformer which massively increases the voltage across the Tx lines whilst reducing current. This reduces resistance across the lines, thereby reducing inherent power losses through heat which would be generated otherwise. This voltage is stepped down however before it is used in our homes, and the max current available is far greater, and certainly enough to kill. '

the bold bit is worng, because the current is stepped down this reduces the heating effect as P= I squared x resistance, the resistance of the wire stays the same but because the current (i) has reduced the heating effect reduces dramatically as why it is used in overhead wires which range from 32000 volts to 400000 volts.

i do agree that ac can kill but from experience i also know that it doesnt always, as i have been schocked myself and you can release under ac current as it spasams your muscles wheras dc locks them tight all of them hence dc is more dangerous. it also matters where the shock comes from as almost all appliances run on dc current and so you may survive a shock from a socket as it is ac but if it has gone through a dc inverter thenm your chances radically decrease.
Click to expand...

Yes you're correct, resistance is a constant, obeying ohm's law in an ohmic conductor such as the copper wires. Had my head in a dissertation for the last 3 weeks to I've been a bit frazzled lol
 
DiscoLew said:
It's irrelevant whether the person is grounded or not, if you touch the live a neutral pins in a socket, you provide a dead short, hence the electrocution.
Click to expand...

Sorry Lew, that's wrong. What kills is the path that the current travels to earth (or return/ground). If you touch the live with your hand and your elbow of the same arm is touching ground, you will get burn points at finger and elbow. If however your other hand is touching the ground point, the path of current will follow the arteries throught the heart and create fibrillation (heart flutter) so that it no longer pumps blood. A Defribillator is designed to send a current through the heart to STOP it and allow its own system to start up again.

Barefoot in a puddle of water is more likely to pass a current than Wellingtons in that puddle.

PS sticking your tongue on a 9V DC (PP3) battery can also kill..... it has happened!
 
Yes you're correct, resistance is a constant, obeying ohm's law in an ohmic conductor such as the copper wires. Had my head in a dissertation for the last 3 weeks to I've been a bit frazzled lol

well its not quite a constant, the resistance also depends upon the temperature, the resistance is usiually given at a standard temperature of 20 degrees i think, as if super cooled resistance can fall to zero, and if heated the resistance increases, the constant is the resistivity of the material not the resistance.
 
Skynet said:
Sorry Lew, that's wrong. What kills is the path that the current travels to earth (or return/ground). If you touch the live with your hand and your elbow of the same arm is touching ground, you will get burn points at finger and elbow. If however your other hand is touching the ground point, the path of current will follow the arteries throught the heart and create fibrillation (heart flutter) so that it no longer pumps blood. A Defribillator is designed to send a current through the heart to STOP it and allow its own system to start up again.

Barefoot in a puddle of water is more likely to pass a current than Wellingtons in that puddle.

PS sticking your tongue on a 9V DC (PP3) battery can also kill..... it has happened!
Click to expand...

The next sentence agreed with what you say above, the irrelevance comment was aimed at disputing the fact that electrocution cannot occur when playing with a mains supply.
 
200tdi ayre said:
Yes you're correct, resistance is a constant, obeying ohm's law in an ohmic conductor such as the copper wires. Had my head in a dissertation for the last 3 weeks to I've been a bit frazzled lol

well its not quite a constant, the resistance also depends upon the temperature, the resistance is usiually given at a standard temperature of 20 degrees i think, as if super cooled resistance can fall to zero, and if heated the resistance increases, the constant is the resistivity of the material not the resistance.
Click to expand...

I'm well aware of that, but it remains fairly constant temperatures we get in this country. Absolute zero is -273 degrees centigrade after all.
 
When I was extending my garage about 20yrs ago I was digging the founds with a wooden shafted pick axe. I was wearing wellies. I chopped through the mains cable for the house, sounded like a gas mains but we dont have mains gas. The guys repaired it without switching the street off. Rather them than me. I didnt get a shock.
 
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