I'm having trouble working out the formula for electrocution. (Yeah,
ok, "Stick your finger in a power point".)
Here in Oz we run 240v which is much nastier than 110v. From what I
read 100mA is very fatal and even 20-30mA can be. But doing the sums
it just doesn't add up.
I measure my resistance to ground with a multimeter and it reads
anywhere from 2M ohms and up depending on shoes, floor covering etc.
Using V=IR on 2M and 240v gives a current of 0.1mA. Is that enough to
kill you?
I well remember welding my elbow to a tuning coil! That was 8000
volts at High Frequency, on a military RF transmitter. I have the
scar to this day, forty years later. Of course there was no
restricion on current to speak of and the thing that saved me was the
muscle jolt that flung me away from the equipment.
Unusual circumstances, I know, but it sure emphasised the lectures
about electric shock I had received up to then.
OK, getting back to 240 volt shocks as opposed to 110 volt shocks: I
have heard, and I have no intention of putting this to the test, that
the percentage of 110 volt shocks resulting in death is higher than
that for 240 volts. This doesn't make any sense at first glance, but
apparantly, 240 volts is more likely to cause just the kind of muscle
spasm that saved my stupid young life, and fling you off the
conductor. 110 volts, on the other hand, just lets you sit there and
sizzle!
Some general points; the condition of your skin, the path of the
current, what you are wearing on your feet and several other factors
will affect the path and strength of the current. Generally, don't
sweat and mess with electricity. Sweat, blood lymph fluid and all the
rest of the goop inside you is, from an electrical point of view, a
solution of sodium chloride, and a pretty good conductor. If you
sweat, this conductor is extended beyond the skin. This, by the
way,is why the poor bastard in the electric chair had a sponge with a
salt solution under the electric skull cap, clean conduction straight
through the brain.
Any amount of current can kill you if it is applied to the heart at
the point where the nerves are firing and it messes up the rythm
completely. There was an interesting article in, I believe,
Scientific american, a few years ago about just this. Apparantly,
during most of the heart's cycle, the effects of current were minimal,
but durting a few periods during the cycle the heart is particularly
prone to damage and failure and a shock then will drop you like a
slaughtered ox.
This explains why some people walk away from a shock which should have
been lethal, while aother die from a relatively minor shock.
Now, about that bear fence; presumably you have a problem with bears,
which means you are living in North America. Have you condsidered the
amount of deep doo doo you could drop into if your fence electrocuted
a child, for example. The litigation would probably bankrupt you!
Also, if it's designed to hurt a bear, it will be lethal to other
animals, deer for example who may touch it with their noses, not to
mention smaller animals.
Now unless you really hate all mammals, that bear fence sounds like a
rather poor idea. Aren't there any alternatives?
John