On 28/02/2019 14:15, Paul Herber wrote:
On Thu, 28 Feb 2019 12:21:12 +0000, bert wrote:

In one bedroom we have a ceiling fan supplied from the lighting circuit.
It's been there for over 10 years no problems.
In the past few nights a couple of times when switching it off the RCD
protecting the ring mains has tripped. But the lighting circuits don't
go through it and the lights are still on including the one which is
part of the fan and the fan itself can be switched back on.
Puzzled as to how this can happen - and where to start looking.

Earthed via a the ring-main circuit?




Probably not, RCDs don't just detect earth leakage but any current
imbalance between live and neutral.

It wouldn't actually matter where it was earthed if there was leakage to
earth and it wouldn't affect other circuit unless they also had an earth
leakage problem as RCDs aren't connect to earth.