Strange RCD fault

[fattony]

Hi

I've been investigating a strange RCD fault in my house this afternoon, there are only 3 circuits on the RCD, GF sockets, 1F sockets and Garage.

It's a Crabtree board installed around 2000

I've tested the RCD a few times at 0.5 and at X1 both test fine, traced the tripping to GF sockets, unplugged everything but still tripping, insulation resistance test is fine.

For some reason when I switch the RCD on and then a MCB the RCD trips again, I can do this numerous times and after a few attempts the RCD stays energised.

I managed to have the RCD stay on and the GF sockets and started plugging appliances back in, fridge trips it out instantly, left it unplugged and reset the RCD, it eventually stays on, bingo I thought, switched 1F sockets on and that tripped the RCD.

I can't imagine 2 faults developed at the same time on 2 circuits so I'm wondering if it's the RCD, anyone had a similar problem?

Thanks

 

[Octopus]

WOT he said ^^^^

Last Friday I went to a house where the RCD wouldn't reset even with all the MCB's off - and the culprit was a new picture hook about 3 foot up the wall from the CU. Great continuity from the MET to the picture hook!

Re pulling the appliances out - this is precisely why I won't install sockets behind white goods any more - sooner or later the RCD will trip and the homeowner or a spark will need to isolate the circuit properly. IMHO you can't investigate a tripping RCD when you have to link L&N together!

 

[fattony]

Havent had much time to look at this today but I did an IR test on the garage and it was <200M, disconnected it from the DB anyway as logic tells me its more likely to be the garage than the upstairs sockets

RCD is holding in and my next move if it stays in will be to move the ground floor sockets back.

Regarding sockets behind white goods, whats your method now then? Years ago we used to install switched spur above worktop controlling a socket lower down, I've carried this procedure on even though its not a requirement of 7671

Thanks

 

[telectrix]

always a good idea to fit the appliance socket in back of an adjacent base unit. i went this way some years ago when , with the socket behind a washing machine was fitted, the bloody machine would not go back as the plug/socket was tight against the metal back of the machine when it still needed to go in another inch.

 

[Dave OCD]

always a good idea to fit the appliance socket in back of an adjacent base unit. i went this way some years ago when , with the socket behind a washing machine was fitted, the bloody machine would not go back as the plug/socket was tight against the metal back of the machine when it still needed to go in another inch.

Very frustrating I'd imagine.

 

[fattony]

Do you still fit a spur above or just the socket outlet?

Update, found the fault, it was a redundant flood light which had been spurred off the upstairs ring

 

[Dave OCD]

Do you still fit a spur above or just the socket outlet?

Update, found the fault, it was a redundant flood light which had been spurred off the upstairs ring

If the socket is in a kitchen base unit it's easily accessible for isolation so IMO another isolator is unnecessary.

 

[telectrix]

Do you still fit a spur above or just the socket outlet?

Update, found the fault, it was a redundant flood light which had been spurred off the upstairs ring

bet it was a N-E fault and/or water ingress

 

[hightower]

Can't believe it took 15 replies until someone mentioned N-E fault. Surely with these symptoms that was the obvious place to look.

Had a mate say every time he turned the outside lights on at the switch it tripped the RCD - full to brimming with water.

Funnily enough, just looked at PIR floodlight for a mate - was working fine with the PIR half full with water. Opened it up and emptied the water and it stopped working.

 

[Jacek Buczak]

Yep tripping rcd sometimes a lot jobs.Last times I have 2 problems with tripping is well one emergency lights water inside ,second times I disconnect every E wire from every outlets socket to find where is problem and problem be in spur from outlet socket with power to strips lights on ceiling.Problem do it lights.

 

[Pat H]

After that much troubleshooting I'd be inclined to drop a new RCD in. it could be intermittently faulty.

 

[westward10]

Yep tripping rcd sometimes a lot jobs.Last times I have 2 problems with tripping is well one emergency lights water inside ,second times I disconnect every E wire from every outlets socket to find where is problem and problem be in spur from outlet socket with power to strips lights on ceiling.Problem do it lights.

Are you a wanna be rapper.