RCD/MCB tripping, nothing plugged in.

[securespark]

To be sure it is a wiring fault, you would have to be sure you have isolated all your appliances fully (ie both line and neutral). This may be tricky to do in all cases.

Consider stuff like outside lights, feeds to and circuits in outbuildings, pond pumps, showers, boilers, kettles, washing machines, dishwashers tumble driers, anything that uses, or is exposed to, water.

 

[SJRSJR]

Thanks for all the replies. I'm pretty confident that other than the cupboard light, nothing else is connected to this circuit.

Yes, the cupboard light is on an FCU. I took the fuse out but the RCD is still tripping.

Can MCBs be faulty? Do you just swap them over?

 

[crystal ball]

MCBs and RCDs can be faulty, fairly uncommon but it happens, next step is testing the affected circuits for earth fault(s), you will need some expertise and the right equipment

 

[SJRSJR]

Thanks. I'll be calling an electrician in the morning

 

[SJRSJR]

Thought I'd let you know the upshot of this.

When I was waiting for the electrician to call back I thought I'd check the sockets on the circuit. Sod's law would have it that the last one was where I found the problem - the twisted 3 strand earth connections had snapped off where they leave the cable casing.

Luckily there was plenty of give so I could shorten the cable and re-connect and now it's okay.

I'm puzzled as to why it happened though. It's not a damp wall and the cable wasn't distorted but there was a scorch mark on the live. It's red/black with white casing - is it just old?

 

[winston1]

A disconnected earth that cannot touch anything else like that should not cause a RCD to trip.

 

[JohnW2]

A disconnected earth that cannot touch anything else like that should not cause a RCD to trip.

Indeed, but given that there was a "scorch mark" on the L, maybe it did 'touch something' at some point!

Kind Regards, John