Re: Potentially stupid question about AC

[supertimer@aol.com (Supertimer)]

CUTblakeney@home.com (Jeff Blakeney) wrote:

>>But AC is self contained, right?  That is, the negative and
>>positive are reversing in the two wires (live and neutral)
>>themselves, so where does the ground fit into the balance?
>
>The ground is a safety feature.  It should never carry any current but
>if there is an imbalance between the live and neutral, the ground will
>carry the excess current to "ground" instead of letting the excess
>destroy your electric device.
>
>If the ground is carrying any current, it is indicative of a problem
>somewhere in the system.

I guess what I'm asking is why the ground absorbs the
excess current.  Electrons going out of one of the two
wires and into the other makes sense because they both
come from the transformer (which in turn steps down the
feed from the power station).  But why does the ground
take the charge?

Is it because the potential difference between the ground
and the atmosphere (the cause of lightning) is so great
that the ground acts as a sink for electrons?  Or are the
electrons going into the ground because somewhere in
the power feed is also grounded (power station or
transformer)?