"scott" <sco### [at] scottcom> wrote:
> >> Nope. As the Wikipedia article explains, there are sprung-loaded plastic
> >> covers that only move out of the way as the earth pin is inserted.
> >
> >  Is it guaranteed that the difference in potential between the earth pin
> > and the physical ground is always very close to zero?
>
> The Earth wires in your house (in the UK at least) are connected to the
> physical ground at your house, usually by being connected to the mains water
> pipe or some similar big lump of metal in the ground.  So I don't think
> there can be much of a difference, there is probably some building standard
> that gives limits on the resistance.  I assume these limits are set so that
> any potentially dangerous Earth voltage would result in the current in the
> defective device blowing a fuse.


do :)
In new builds you will often find a metal rod driven into the ground as an
earthing electrode.

--

Stephen

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