"Huge" wrote in message
...
On 2017-12-29, Peter Parry wrote:

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The hood may have little to do with it. It could be the result of a
Neutral to Earth fault anywhere in the house. This can cause a
leakage current just insufficient to trip the RCD. When the cooker
hood is switched on or speed changed there is enough (harmless)
inductive coupling to surrounding metalwork/cabling to trip the RCD.

A friend once had a house where plugging an extension lead in was
fine - but as soon as you walked out with it and put it on the grass
(with nothing plugged in) the RCD tripped. The fault was eventually
traced to a nail through the upstairs ring which bridged neutral and
earth.

Just to cheer your holiday up these faults can take ages to find.

Just to cheer you up even more, we've been trying to track down a
similar fault for 2 years now.

Why can't you find it by measuring the leakage, then turn breakers
off in turn until it goes, then break that circuit in half chop method
until you find where its got the problem ? Nothing even remotely
like 2 years to find it.