"Mano" wrote in message
...
Andy Wade wrote:
Tuthledeen wrote:
"Mano" wrote in message
...
OK open to ideas here with this one :-

Switch off individual breakers and see when/ if the problem goes away.
[...]

If the problem doesn't go away at all using any of the checks above you
then, most probably, have a defective MCB.

Not necessarily true. A neutral-earth short anywhere in the installation
(or an appliance) could cause the reported symptoms. Isolating individual
final circuits would not help in this case, unless the OP has double-pole
MCBs (unlikely).

I think you may have some confusion between the function of an mcb and
that of an rcd.

So do you, judging by your reply above. Anyway it's fairly rare for RCDs
to become defective and when they do fail they tend to become
insensitive, or won't trip at all, rather then becoming over-sensitive.

A faulty appliance is the most likely cause. Start with washing machine,
dishwasher, fridge & freezer (esp. if frost-free type), immersion heater,
toaster. Unplug or isolate these completely, such that the neutral is
disconnected too.

Ok all thanks for the ideas is switching of a circuit at the MCB enough to
issoloate everything on that leg or not I am suspicious of a freezer in
the garage but having turned off the seperate consumer panel there had
discounted that are we now saying I should have unplugged the freezer to
test this idea?


If you switched off the main switch in the garage CU (double pole)
then you have eliminated everything fed off it.

--
Graham

%Profound_observation%