Power cut trips Rcd

[Belle427]

On a couple of occasions a power cut in the night has tripped our consumer unit Rcd. Luckily ive been half awake and also the neighbours alarm battery must be dead as it sounds until power is restored!
Anyway, i had trouble resetting it when the power came back on, i had to turn off the 3 mcbs it protects and it was then ok.
Seems odd it should trip with a power cut, has anyone seen anything like this before?
Ive enclosed a picture of the offending side of the board.
Just to add its a Pme supply.
Thanks in advance.

 

[securespark]

Well, the first thing I would do is test the RCD and give it a ramp test.

Then I would check your wiring for insulation resistance, but both these tests need specialist equipment.

It is odd that an issue potentially on the incoming supply should trip the RCD.

 

[ban-all-sheds]

Anyway, i had trouble resetting it when the power came back on, i had to turn off the 3 mcbs it protects and it was then ok.

Has it done that before?

For some RCDs that is normal behaviour.

 

[Belle427]

We have only been at this house 6 months but yes it has tripped out with some power cuts previously.
It has not tripped out though for any other reason in normal operation.

 

[ban-all-sheds]

Anyway, i had trouble resetting it when the power came back on, i had to turn off the 3 mcbs it protects and it was then ok.

Has it done that before?

For some RCDs that is normal behaviour.

 

[Risteard]

Well, the first thing I would do is test the RCD and give it a ramp test.

The 1/2 current test will already have proved that it isn't oversensitive. The ramp test will add nothing.

 

[securespark]

Perhaps more accurately, The 1/2 test should have proved....

 

[ericmark]

My house is the same, not always, but often it will trip with a power cut, they are very old today I know I could get better models less prone to tripping in electric storms and power cuts, it's on my to do list. Also common when resetting one the other will trip, tested many times, passes the 1/2 test, both identical but one with most circuits on it I can do a ELI test, the other always trips. Fitted in the 90's it seems they have a run of trips, may trip once a week for two months, then will go 3 years before next trip, and nothing done to the installation between. Simply the old trips are more sensitive to spikes on the supply.