[Shop-talk] How likely am i to be able to pull electrical wire?

[Carl Lindahl]

I would agree completely. The mouse or rat, or rodent could have been
fairly well insulated until he chewed though both the hot and either
ground covering or neutral that knawing the hot leg didn't do
anything.

Assuming the rodent was in the wall it was stuck against romex, a 2x4,
fiberglass insulation (if present) and sheetrock, none of which are
good conductors, some are even "fairly" good insulators." With the
right conditions in the wall the rat could have easily chewed all the
insulation off of the hot wire and without touching the ground or
neutral, been fine from any electrical shock.

As soon as the rodent crossed either the neutral or ground wire this
is where you probably noticed the arcing and other fine events. As
stated below his high resistance would only let a few amps flow
through his body compaired to a dead short which would trip the
breaker.

I don't have any numbers, but assuming the rat could conduct even 10
to 20 amps, if the circuit was a 15 or 20 amp breaker, the rat "short"
would not have tripped it because of the high resistance. A dead short
would pull a much larger amount of current imeaditly and pull the
breaker open.

I have seen rodents before in outdoor disconnect meet their fait and
no one knew the better because they can't trip the 15, 20, 30, 60 amp,
etc breakers.

Then you could always looks at the nice "electronicly adjustible" trip
breakers that some 3 phase industrial sites use. You can move the trip
around to suite your needs, all except for a dead short.

Carl

On 6/25/07, Randall <tr3driver at ca.rr.com> wrote:
> > My question is, why didn't this trip the breaker? And why did
> > it keep working for some period of time? (How long does it
> > take for a rodent to become a skeleton inside a wall?) There
> > was clear evidence of arcing -- the paper that wraps the bare
> > ground wire was charred. I replaced the breaker, on
> > principle, but it is a bit worrying.
>
> Just a WAG ... I'd say the "short" was through part of the mouse and high
> enough resistance that it never drew enough current to trip the breaker.
> Most likely the wire was not chewed through all the way, only partially, and
> it later broke from thermal flexing or whatever (same thing that makes old
> floors creak when no one is walking on them).
>
> Randall
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