"Francis Burton" wrote in message
...
In article ,
greenaum wrote:
But yes, deadliness is determined by current flow and time. But

It may take only a very short duration pulse to 'stop' (fibrillate)
a heart, especially if it comes at the right time, in the T-wave of
the ECG. The current required to do this is less than would cause
damage through electroporation. The reason that 50Hz (or 60Hz) AC
current is dangerous, even at relatively low, non-burning currents,
compared to DC, is that it exposes the heart to a long series of
shocks, increasing the probability of one of them being at exactly
the right time to induce VF. (AC will also pace the heart at a fast
rate, increasing its susceptibility to VF for various reasons.)

Conversely I've heard that a DC shock of the same voltage and current as the
RMS AC equivalent can more dangerous because the muscles of the hand will
contract permanently around the live object whereas with AC they will
contract on one half-cycle and expand on the next half-cycle, increasing the
chance that the victim will be able to pull his hand away.

But ideally you want to avoid the shock altogether. Having had a mains shock
from the terminals in the power switch of a telly (turned off at the switch
increas of the wall - blush!), I don't want to repeat the experience: even
though it was just across either side of a knuckle, my whole arm was numb
and tingly for about an hour afterwards.