On 27/12/2010 20:26, Fredxx wrote:
On the other hand ice is more resistive than water, so any current you
can pass into the stopcock will largely heat only the plugs of ice.
Assuming the plug of water the other side is earthed somehow! It might
also be a good idea to isolate the internal piping first.

No chance of getting an earth through water in a plastic pipe if it's
more than a metre or so long.

--
Mike Clarke