Help from the electricians please

Hi, I'm having a problem with a 30mA trip tripping and I hope someone on here can help before I have to call someone out. (Does anyone live near Durham and fancy a job?)

The main 30mA trip tripped earlier and by trying the circuits one by one, I've isolated the fault being in the upstairs socket circuit. So everything has been either unplugged or switched off at its spur unit but each time I try the upstairs circuit back on it trips again.

Any suggestions on what I should do next or is it time to call out the pros?

 

Unless you fancy starting to strip down the ring final circuit and finding where the fault genuinely loes then youve done as much as you can, as long as everything is disconnected at spurs/unplugged

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If the RCD is tripping, unplug everything, turn the breaker off and unscrew all the sockets from the wall to check the connections. Possible that you have a short from neutral to earth.

 

It depends how confident you are with electrics. While the circuit is isolated, I'd unscrew all of the wall sockets and make sure no wires have come loose at the back and that the terminals are nipped up tight. Also that the earth wires are ok. Quite often a few wires may go into one terminal, especially where a spur is taken, and being solid core it's easy to apparently tighten the terminal screws but not effectively trap all of the wires to make good contact.

If that doesn't sort it then it could be an issue with the cable itself (damaged after being trapped under a floorboard or something?) and call in an electrician. Certainly do so if the wiring itself looks old or damaged

 

Unless you have double pole spur units then they will still trip the 30ma RCD if the appliance connected to the spur is faulty. I'd also go around the whole house and unplug everything in case the installer had spurred off the upstairs ring circuit to fit a socket elsewhere, happens a lot for sockets directly below or perhaps for an attic socket. If it still trips afterwards then my money is on a damaged cable probably from a plumber wrapping a pipe around it.

 

Thanks everyone for the info. I've assumed the switched spurs were double pole and it was enough to switch them off but maybe not. We've had a lot of rain lately and I think something outside is the most likely fault, we've security lights from the spurs.
I'm a bit baffled since no work is being done on the house etc and I believe it was rewired 7 or 8 years ago.
I hadn't thought of sockets etc being spurred elsewhere in the house. Good call, I'll check that now.

 

Water in an outside light would definitely trip the RCD

 

Slugs make quite good RCD test trip elements, crawling into wiring, or hiding in 16amp outdoor connectors.

 

Could be Mynocks. They like chewing on power cables.

 

Got to be plumbers.

 

I hope not, not a clue how to get rid of them!

 

I still haven't found the fault but have discovered that the utility room sockets are on the upstairs socket ring and the conservatory is spurred from the utility room.
Really handy as it means the freezer has been off most of the day!

I'm beginning to think a plumber wired the house, which no doubt explains why radiators are packing in one by one, as an electrician must have done the plumbing. I think it's called diversification!

 

Obvious question: have you done/added anything new that's kicked this off?

 

No, not a thing. That's why I'm especially baffled. All I can think is the weather but even with the outside light spurs switched off the RCD trips instantly.

 

@Barry Haynes
What? no jibes about spurs?!

 

What, plumbers? Just tell them you’ve run out of custard creams.

 

Have you checked if they are Double Pole spur units? If they're not then you need to disconnect the outgoing cables to the outside lights to confirm the lights aren't the cause of the tripping. I think Double Pole spurs have DP stamped on the back?

 

Thanks for the reply.
So far I’ve discovered two unswitched spurs in the utility room are just being used as junction boxes since both lives go in the same terminal, with both neutrals connected straight together as well. Another switched spur (for an outside light) is wired correctly.
I’ve separated them all but the RCD still trips.
About to continue removing sockets upstairs.

 

The switched spur that's wired correctly ' have you physically disconnected the outgoing cable that goes to the light? If you don't disconnect it the neutral path is still active and will trip the rcd if the light or outgoing cable is faulty/wet.

 

Yes, I’ve got all the wires (apart from the earths) disconnected and separate.