[Greenbuilding] Electric shock
Joe Killian
kaa-ajk at sonic.net
Sat Feb 7 14:14:46 CST 2015
Ben,
I know exactly what touching 110V feels like. Just yesterday I was
talking with our testlab manager about our high-school experiences with
electricity, which for both of us included many occasions of touching
110V AC, as well as higher DC voltages in radios & TVs & automotive
spark coils & Van DeGraff generators, 300 VDC to several or many
thousands VDC. Many of the occasions would be on purpose. No perceived
ill effects (unless you consider how crazy we appear :-) ).
In the course of obtaining my college physics & EE degree, I came
across information that some 10 to 20 milliAmpers Through-the-heart was
sufficient to cause the heart to stop, a definite ill effect. But, as
you point out, to go through the heart the current has to enter
somewhere and leave somewhere else on the other side of the heart, so
being ungrounded, and especially working with one hand only, one is
pretty safe. Birds sit on power lines all the time - thousands or
hundreds of thousands of volts, but only touch one voltage. They leave
later no worse off for their perch. (I have witnessed a jay that spread
it's wings & touched two wires at different potentials - he ended up
fried & on the ground.)
Even with being grounded or using two hands, getting the dangerous 10
to 20 milliAmpers to travel through you is not at all guaranteed unless
the voltage is high (like thousand or more), or you contact VERY firmly
- otherwise the contact resistance is too high to permit that much
current. I've grasped resistance leads many times seeing how low I
could achieve - takes a very firm grasp or puncturing the skin to get
resistance low enough to warrant worrying.
So the bottom line is don't worry about it at all.
That said, I do turn off the breaker before working on house wiring -
unlike the father of our testlab manager (but it never hurt him either).
Joe
On 2/7/2015 11:30 AM, Benjamin Pratt wrote:
> All-
> Quite a bit of googling has not answered my question so I thought I'd
> ask here. If I shock myself on 110v current while ungrounded (wearing
> rubber soled shoes on a wood floor for instance), is it dangerous or
> harmful to my health? It doesn't really bother me much but many people
> seem to think it is really dangerous and harmful. I try to avoid being
> shocked, and have never been shocked while grounded, but I have been
> shocked while ungrounded numerous times without any lasting ill effects.
> Ben
>
>
>
> b e n j a m i n p r a t t
>
> professor art+design
> the university of wisconsin stout
>
>
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