UK RCD issue baffling me

[brianmoooore]

It could be an abandoned cable going nowhere. In a case like this, I'd fully disconnect it and wait to see if anyone complains.

 

[mainline]

It could be an abandoned cable going nowhere. In a case like this, I'd fully disconnect it and wait to see if anyone complains.

In a case like this, I would advise calling a decent electrician.

 

[ChiliTom]

Sparky is coming back tomorrow. Now I've found the problem cable he can try and figure out what it does, I've absolutely no idea. It was actually in a connection block behind a mirror, but runs off somewhere random.

 

[MikeSp]

I have a dual board consumer unit. Both sides have a RCD. The left hand side of the board has all the MCBs for all the 6 ring mains for the property. The right side of the board has the lighting and hob and cooker for the house.

Whenever a current is drawn from a socket the right side RCD trips, but not the left side. So my lights trip but sockets stay on. It happens on any of the 6 ring mains. And seems to be any appliance that draws a large current such as a hoover, kettle, immersion heater etc.

I do have a alarm system but I have totally isolated it by unwiring it front the spur it was connected to. Still the same issue.

I do also have under cabinet lights that are ran from a ring main... I have yet to investigate these.

The MCBs switched off were because they were just straight up tripping the right side RCD. Probably because they all had stuff like a fridge, boiler etc drawing current. The right hand side lighting circuit that is turned off also automatically trips the right RCD.
View attachment 118549

Electrician has tested each circuit and can't find a fault. The board has been wired correctly with no crossed over neutrals.

Anyone got any clue where to start some more fault finding? I am a ex Army Electrician, that was 17th ed trained... But that was about a decade ago but I know enough to be safe.

Cheers

I had a more confusing version of this. Switching on a kitchen socket caused a RCD on a different CU to trip.

The cause was found to be a squirrel nibbled cable, with the neutral and earth shorting. Easy to fix after the exceptionally difficult task of finding exactly where the cables were chewed.

 

[ChiliTom]

Turns out it was a wire that fed the dinning room lights from the connection behind my mirror... Strange. Stripped the old cable out no visible damage at all but was faulty. New wire installed and all good. Just a few holes in my wall now

 

[brianmoooore]

no visible damage at all but was faulty.

Seen this where T&E has been fixed with a flat bend of too tight a radius.