Bob Eager wrote:
On Sun, 25 Nov 2007 15:44:31 UTC, "Graham." wrote:

Particularly suspect anything that is closely associated with water
Kettles
CH water pumps
Junction boxes exposed to the elements

And immersion heater, if you have one. A previous house of ours had a
corroded immersion heater and it did just this (as it should).

Interesting option we do have one but its turned off never used. Does
that rule it out ?