RCBO keeps tripping - without explanation

[pads]

The wiring in the house is split into separate circuits each with their own RCBO for
3 for lighting (separate for ground floor; upper floor; and basement)
3 for power (again as above)
1 for cooker
1 for shower
2 for fridge/freezers

The problem exists only on the ground floor power circuit.
Whenever the vacuum (two core) is switched on in any socket, the RCBO trips. It's not the vacuum as it dos not happen on the upper floor. I have even tried an angle grinder- thinking maybe induction issues - but it does no trip.

Occasionally the circuit trips on its own, or if the computer is switched on.

I've checked all the sockets for damaged or trapped wiring, but nothing found.

Does anyone have any suggestions please.

Thanks
Peter

 

[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.