In article , John
Rumm scribeth thus
On 13/02/2011 23:36, Felicity S. wrote:
Andrew wrote:

When you have current leaking through the ground, it causes a
voltage difference across the ground. Let's say we're standing
on a piece of ground which has a voltage difference of 10V/foot.
Your feet are probably about a foot apart, and even with bare feet,
you wouldn't even feel 10V. Even if you did, the current path (up
one leg and down the other) isn't going to kill you. A horses feet
might be 6' apart, so it's going to have 60V across it. Futhermore,
that will be across the chest (heart, lungs) and much more
debilitating. Metal shoes will make better ground contact, pressing
right into the damp soil, although it's a very serious problem for
unshoed livestock too.

In that case, what voltage *would* it take to kill a human, when the
current passes through each leg and not across the chest?

Voltage is a bit of a non issue in this case. Its the magnitude of the
current and duration that will largely dictate the level of injury along
with the general health and state of the victim. Obviously higher
voltages make it easier to push the current through the body, and high
enough ones make possible severe injury from follow on effects like arc
flash.




The volts is the most, or most important part as you can have Mega amps
at say 1 volt thats not, well unless its connected perhaps to electrodes
buried in the brain, going to have much effect through the average Joe
or Horsey.

Course you can have Mega Volts at a yoctoamp and thats not really going
to have an effect either..

The matter is a combination of volts, the current capacity of that
source. The Resistance of the connection to the victim and the
electrical source and the resistance of the victims skin and the path of
the current..

In the case of a Human from one leg to the other is less dangerous than
from hand to hand which has the Heart etc in the path.

Course sufficient volts across whatever member of the body can cause
debilitating effects and heating burning and possibly death...


It seems to me that in this case there must have been quite a voltage
gradient across that ground either from a source that had the "other
side" of itself earthed elsewhere, or possibly two conductors a distance
apart and the flow was across the ground. Course we'll see what the
official line is from those investigating..
--
Tony Sayer