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Technically Dead: Electrocution
By Mark Kinsler

[ Yesterday John Tuttle wrote about his wife wading
 [ in water where a live extension cord was plugged in...

The reason that nobody felt a shock was that his or her body wasn't in
a position to complete a circuit.

First off, water isn't as conductive as all that, unless it contains a
lot of dissolved salts.  Second, any current that flowed out of, say,
a "hot" slot in one of the outlets very likely found its way right
back into the neutral slot.  That would be by far the lowest-resistance
path it would have found.

As to the movies, please don't depend upon filmmakers and journalists
for technical education.  These guys know nothing, and many of the
experts whom they consult know even less: how many inaccurate
representations of mechanical music devices have you seen in
entertainment media?

Perhaps the commonest incidents involving water and electric power are
those involving a AC radio or hair-dryer that falls in an occupied
bathtub.  Occupant is in bathtub, where he is firmly connected to the
neutral wire of the power line through the ground provided by the
plumbing.

Then it's the hair-dryer's turn to take a bath.  The machine is plugged
into the wall outlet, so there will be one or more exposed contacts
exposed to the inrushing water.  The water is rendered more conductive
by soap or bubble bath.  This doesn't affect the bather, because
almost all of the current that flows goes through the water and up the
neutral wire of the hair dryer.

But the terrified bather sees the situation and, not bothering to
realize that he's still alive, grabs the hair dryer and lifts it out
of the water.  If water bridges the gap (from terminal to the plastic
hair-dryer case and from case to hand) between the hot terminal to his
hand, _and_ if the neutral terminal in the dryer is no longer immersed,
current will flow from hot terminal to hand, through the unfortunate
bather's body, and thence to the plumbing, which is connected to the
neutral line of the power company.

The police find a body and a hair dryer, both floating in the bathtub.

And you darn well ought to have ground-fault interrupters (residual-
current interrupters in Europe) connected to your basement, kitchen,
and bathroom outlets.  Hair dryers all come with these devices built
into the cord nowadays.

M Kinsler
512 E Mulberry St. Lancaster, Ohio USA 740 687 6368
http://www.frognet.net/~kinsler

 [ Mike Ames reported a story to me where he was swimming in
 [ a swimming pool with a broken light fixture.  As he swam
 [ towards the broken fixture (which he was unaware of) he
 [ began to feel the shock get gradually stronger.  He turned
 [ around and swam the other way and lived to tell about it.
 [ My recommendation:  Don't try this at home!    Jody


(Message sent Thu 30 May 2002, 17:40:05 GMT, from time zone GMT-0400.)

Key Words in Subject:  Dead, Electrocution, Technically