Help! Sockets keep tripping with all appliances unplugged!

[mevtickin3]

Hi guys, really would appreciate some urgent help.

Just come back from holiday to find house with no power. Checked the mains board (which is about 10 years old) and the rcd had tripped. I reset it and after exactly 10 seconds it tripped again. I went and unplugged everything from the sockets and switched all fused spurs off, tried again but still trips. I have found that I can get it to stay on if I have just 1 of the 2 socket mcbs on (they are both just labelled sockets), and this gives me power to the kitchen and utility sockets but no others!!! so I have to assume that the sockets ring has been split into kitchen/utilty and 1 for everything else. It's the everything else mcb that keeps tripping, always after exactly 10 seconds???? The mcb is a hager mt132/b32, and the circuit is rcd protected on the hager fuse board. Lights, cooker, heating all work fine, it's just that ring of sockets which have nothing plugged into them. Oh and I haven't changed anything as I was away when it tripped

I would really appreciate any help, as I'm literally powerless.
Thanks, Gary. [/b]

 

[Spark123]

Could be a N-E fault on one of the circuits, you say you have unplugged everything? Did you switch all fused spurs etc off? Any outside lights?
Failing that you'll need an electrician to Insulation Resistance (Megger) test the circuits.

 

[mevtickin3]

Thx for the reply. I've checked all fused spurs are off too, what is a n-e fault, and what would cause it as it happened whilst the house was empty sometime over the last 2 days. Prior to that all was good.

I have insurance for home services up to £500, should that be adequate if it is what you suspect?

Thx again, and is there anything else I can try in the meantime, ice checked some of the sockets for loose cabling all fine so far.

 

[Spark123]

N-E is a neutral to earth fault, it might be or it might be a live to earth fault with a bit of resistance in it.
Any outside lights?
Not sure on your insurance, you'll have to ask them.

 

[mevtickin3]

Yes we do have outside lights, but they are all turned off at the relevant fused spurs. That's the things, everything is turned off, so I don't understand how the RCD can trip without anything connected?

Is it a fault actually in the mains wiring then, and if it is should I check all the sockets for good wiring. And can I assume the problem is isolated to the sockets given that is the only RCD tripping?

Many thanks for your help, it's appreciated.
Gary.

 

[sparkwright]

have you any UNswitched fused spurs anywhere? are you sure any sort diy work wasn't done just before you went away?

 

[ColJack]

suspended floor downstairs? ( ie floorboards ) ?

might be a mouse or rat problem...

View media item 9882

 

[mevtickin3]

oooohhhh update: Pulled out the fuse from the unswitched fused spur and it's alll good, there must be something wrong with the outside socket! water ingress perhaps... I'll check it in the morning and leave it isolated for now.

Thankyou so much for your help.... It's really appreciated guys...

 

[sparkwright]

Thanks, there is an unswitched fused spur, which I think is for the outside sockets. What shall I check on that? replace the fuse?

the easiest way to confirm if there is a problem here would be to disconnect the load side live AND neutral. then restore power and see if it stays on.

reason for doing this is just removing fuse wouldn't disconnect the neutral.

 

[ColJack]

ah.. outside socket..
go outside and open it..
it's probably full of water..

 

[mevtickin3]

oooohhhh update: Pulled out the fuse from the unswitched fused spur and it's alll good, there must be something wrong with the outside socket! water ingress perhaps... I'll check it in the morning (it's dark) and leave it isolated for now.

Thankyou so much for your help.... It's really appreciated guys...

 

[mevtickin3]

It wasn't filled with water, but it had been installed (before I moved in) without the grommit at the back, and it looks like some moisture had corroded the wiring and terminals.

I replaced the socket and all works fine now. Thank you for your help diagnosing this.