RCD trips when power lost

[yellowvanman]

Customer complaining that RCD trips when there is loss of power - lives out in the sticks and had some power outages during the winter storms.

CU is an old Wylex fuseboard with a 30mA RCD at the front end. TT earthing. RCD trips OK on test.

Can replicate the fault by simply turning off the main switch on the CU. Doesn't seem to be related to any one circuit being energised at the time of switching off.

Can anyone think of why the RCD should trip when power is lost or when the power is turned off?

Am planning to replace RCD with another and see if that exhibits same problem.

 

[sarky spark]

Active RCDs will do as you describe.

 

[Octopus]

Could simply be a knackered RCD - what were the test results like?

Worth trying a new one

 

[malcolmsanford]

You say that it is an old Wylex board. I'm guessing you may have the old Voltage operated RCD affectionately known as VOELCB.

These work on voltage fluctuations rather than earth faults and are often activated during electrical storms.



Would this be the beastie ?

 

[alanl]

If it is a VOELCB, then it should be changed, as I doubt it has been tested in many years.

 

[Knobhead]

If it is a VOELCB, then it should be changed, as I doubt it has been tested in many years.

I doubt anyone's got the gear to test it.

As I recall it’s done by voltage injection to the trip coil.

 

[telectrix]

my VOLCB tester.

as in a witch trial. if it breaks, it's innocent. if it survives, it's guilty.