::bows to the Gods of Electricity here in this thread::
Una (who loves coal but hates electricity)
Link to one of the earlier threads where this shocking issue was discussed:
And a double bow to the kinky coal goddess. 
Crafter Man Is the Authority here, he is completely correct.
…however, it is the amount of electrical energy relative to the period of time in which it is delivered, that kills.
Circuit conditions will tend to be as previously described, but this explains why you can play with high voltage lines and not be killed and yet it is possible, under unusual conditions, to be injured by a 50 Volt supply.
It can be a very capricious thing, electricity, as a circuit might not be capable of delivering a lethal shock continously but might be able to store enough power for a one ooff shock, and the path the current takes is critical, you may survive a massive shock of tens of amps if it takes a route away form the heart(say from one part of your hand to another- a fairly common mode of electric shock), and yet be struck down by a flash that would not illuminate a 50 Watt lamp.
A medic would be able to provide a figure for this, but think along the lines of emergency rescusitation procedures.Here the shock delivered is in joules (electrical energy is measured in joules per second=Watts)
This energy may be required to stop the heart, in defibrillation, and then restart it.
Don’t forget that the majority of your resistance to current flow is in your skin.
A bleeding cut on both hasnds makes even small voltages with the capacity for large current fow ( car battery) can be quite deadly…
(hand to hand with your heat in the path)