Would I be right in thinking the only culprits (appliance wise) are
those
that have an earth connection - so I can disregard all double
insulated apps
(which I think is most of them except kitchen apps)?

well, the earthed ones are far more likely culprits, thought its not
quite a 100% thing. Nearly though. Prime suspects are always things
with water heating elemtns in: washing machine, dishwasher, kettle,
oven as well, and the biggest cause of all is immersion heater.

Well the immersion heater was removed a few months ago so thats not the
problem (very scary when I looked at the connections on the element btw -
how it had never burst into flames I'll never know!)

Alternatively, insulation test or pat test all appliances,
including
the fixed ones. Of course it'll cost you.

Hmmm, last resort...

Why not test everything with a multimeter first? No guarantee it'll
pick out the duff appliance(s), but it usually will, and its cheap and
easy. Check resistance on max R range between earth and (L&N connected
together). Suspect the item(s) with the lowest insulation resistance
reading.

Note: make sure the switch on the appliance is on, and item set to
boil, otherwise you'll only be testing a part of the appliance.
Obviously I dont maen it should be plugged in during test

Worth a try I guess - wasnt sure how well a multimeter would work on this
without sending high voltages around, but I'll get the Fluke out and see if
anything turns up.


cheers.