On 27 Aug, 14:11, Fred wrote:
Title says it really.
Yesterday we had some lightning which obviously led to some supply
issues resulting in flickering supply.

I thnk I reset the breaker 10x yesterday
I've tested the RCD and it trips at exactly 30mA.
[Tested by connecting 1 through 6 *47K resistors from live to earth -
each adds 2mA of leakage.]

I had a visit from EDF a few months ago. The first guy found something
that I believe is key. *[Not certain of the exact numbers here as I'm
working from memory.] He said my earth imedance was 0.37 ohm to
substation, and the spec limit is 0.38 ohms..

Then [just to get out I feel] he said he would arrange for a voltage
recorder for a week or so. Of course everything was perfect during
that period, so no action.
I called up EDF again today and got through to someone who insisted it
is my problem and that their supply could not possibly cause my
breaker to trip. Further the earth impedance is in spec - even if
1/100 ohm from spec. I really didn't like his atitude.

Any suggestions ?
I'm at the end of my tether and tired of re-setting the clocks!
My ideas (pssibly off the wall) include:
1. 100mA breaker instead of 30mA - but I don't like the loss of safety
protection so it's a last resort.
2. I believe it may be related to capacitance of the wiring as it's a
large extended 70s house. I'm thinking about adding a 240VAC rated
capacitor(s) at the entry point to try and swamp my wiring
capacitance.
3. Add my own earth spike to reduce earth impedance.

Thanks,
Fred

In days of yore, RCDs were very prone to tripping due to transients in
the system. New ones are much better. It's possible you won't find
any insulation problem at all or even the source of any transients.
If this is the case, if you RCD is old, a new one may well cure the
problem.
The source of any transients may not be in your property at all.

It's not possible to completely test out RCD devices at home, often
substitution is the answer & see what happens.