xena explained on 04/07/2007 :
I don't get this leccy thing at all. 12v doesn't hurt if you touch both
terminals.

It does if the voltage is enough to overcome the resistance of your
body. The highest resistance is normally that of your skin. Try the 12v
on your tongue - on second thoughts perhaps not. Try the 12v via a
couple of pins in your skin.

The voltage has to be enough to overcome your body resistance...

My electric fence at 8,200V (yes 8.2KV) stings a bit but doesn't
kill,

...and the current enough and for a long enough period to do damage.

yet somewhere in the middle, 1mA at 240v can kill??

It can, but it depends upon the individual, the exposure conditions,
the current path through the body and of course the length of time of
exposure to the current.

The worst possible route for the current is in one arm and out the
other, via the heart - hence the good working practise of working with
your spare hand in your pocket body covered and well insulated dry
shoes. The worst you can then suffer is a belt across your hand.

An old party trick I used to do was to allow the 30Kv spark from a
colour CRT TV, to arc across to my finger tip. Very high voltage, but
very little actual current - due to my normaly dry skin I don't usually
feel much.

Even the 10mA RCD's are not certain to prevent death and or injury, but
they do limit the time of exposure to a very short time period. They
are a delicate balance between protection and nuisance tripping due to
normal circuit leakage currents.

--

Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk