When working with electrically powered equipment the most obvious threat
is that of getting an electric shock.
The danger is electric current overcomes the electrical signals sent
by your brain to control muscle movement, this can cause the muscles affected
to go into spasm. You should bear in mind that the heart is a large muscle which can
be stopped by the electrical surge.
A current in excess of 10mA (10 milliamps) flowing through the body can
paralyse the person receiving it, The person would be unable to get free
from a live power source.
Dry skin has several hundred thousand ohms resistance
to electrical current flow. When your skin is wet, cut or pierced by a
strand of wire the resistance is very much less; possibly as low as a
few hundred ohms. Under these conditions it is possible to receive a fatal
shock from voltages as low 30 volts.