RCBO keeps tripping - without explanation

[telectrix]

yep. could just be a N skinned a bit. i had a FCU the other week was damp and tracking across terminals.

 

[gazj82]

Disconnect the bad circuit and test against the circuits in the board. The times I have changed a board to RCBO's to find out some bugger has nicked a nuetral from a ring main for a lighting circuit.

Also check no sockets on this ring have neutral and earth switched. i.e maybe where your computer is plugged in. Obviously any appliance plugged into a socket like this will create a fault to earth. (probably irrelevent if you are sure you have unplugged everyting.)

 

[pads]

I have fingers crossed - think I have found it.
There is a fused spur outlet which has not ben used for about 15 years (and I had almost forgotten about).
Had some panelling put in recently and guess what must have nailed through the cable.
Luckily the outlet is actually on a spur (not directly on the ring). So I've disconnected t.

On testing the cable to the fused outlet (now hidden behind panelling) I get those very same low insulation results.

So hopefully case solved.

Thanks for hints folks

 

[Guest111]

had one very similar and it was a neutral on a socket,just the tiniest score in the insulation caused by a fixing screw,you could hardly see it when you removed the socket but it was just the way the cable had been pushed back and made contact with a screw.