RCD tripping

[KennyMac]

The RCD on my consumer unit keeps tripping.

I've isolated it to the MCB labelled cooker - if the MCB for this is open no trip, if it is closed it the RCD immediately trips.

If I turn the both the cooker switch and the plug on the same gang plate off, the RCD still trips so I'm fairly sure it can't be the cooker itself.

Any ideas or is it time to call out a sparky?

Thanks in advance...

 

[ColJack]

look in the switches and sockets for a dislodged wire..
failing that it's time to trace and eyeball every inch of the cable back to the board.. ( which most likely you can't do as it's sunk into the wall?? )

put any new shelves or cupboards up recently?
heard any scratching under the floors?

if it all looks ok ( or you can't be bothered to rip up floorboards etc ) then it's time to call in a sparky who will test the cables to see if there's a short or a breakdown in insulation somewhere..

 

[JohnD]

this might be caused by a screw or nail in the wall damaging a cable. Can you think of one?

or mice gnawing the cable

as ColJack alludes to

 

[KennyMac]

Thanks for the suggestions so far...

I've done no DIY recently (in fact I'm moving house in the next couple of months - typical eh?) and can't say I've heard any scratching.
Went to bed one night and everything was fine, woke up in the morning to find RCD tripped.

I've already had the plate with the switch/socket on but all wires look secure. There is one suspect earth that has had it casing cut so that you can slide about the last 2 inches of it up and down into outer grey cable. I can't access it easily as it is tucked away under a cupboard and I obviously don't want to pull the cables too hard to see how far the bare earth goes into the grey cable...

I wondered whether it could be a faulty switch or MCB or something...

Nevermind, looks like I'll have to get a sparky out.

Thanks again anyway...

 

[ColJack]

the earth is fine, it's not insulated inside the grey bit, we add the green and yellow sleeving when we strip it back to terminate it..