Backbox trips RCD

[shaemoan]

I have replaced a backbox as the old one was not deep enough to accommodate a new socket. However it keeps tripping the RCD.

With the socket not screwed in with the face plate screws and the earth lead to the backbox disconnected, everything works fine. As soon as an earth connection is made (either screwing socket in or attaching the fixed cable) it will periodically trip. It might take 5 minutes or 12 hours.

It is defiantly this socket as with it hanging off the wall there have been no trips for long enough for me to eliminate anything else.

I have checked I didn't knick any of the cables and everything is in its hole far and tightly.

Any help with this would save me from insanity.

 

[PrenticeBoyofDerry]

Is it a metal or plastic socket?
Is this the socket that was originally installed prior to increase backbox depth?
Are any of the conductors damaged?
Have you sleeved the earth?
You have connected the correct conductors to the correct terminals on the socket/backbox?

Any pictures of this to upload?

Does it only trip whilst the circuit is energised?
Is the socket not loaded at the time of the tripping/nothing plugged in to it?

Try taking the socket plate off altogether, connect the lives together in a connector, in a separate connector connect the neutrals together and then the same with the earths if all is good, then connect the earth to the backbox and hopefully no trip and we can blame the socket.

 

[flyingsparks]

Did you drill any holes to fix the back box to the wall? Or did you use longer screws? If there was another cable behind the back biz and it got damaged, when earthing the box it could cause this to happen

 

[PrenticeBoyofDerry]

Did you drill any holes to fix the back box to the wall? Or did you use longer screws? If there was another cable behind the back biz and it got damaged, when earthing the box it could cause this to happen

That was my next question!

 

[shaemoan]

It is a metal front socket which is replacing an old plastic socket. The old socket was damaged but not causing any problems that I could see, but still wanted replacing.
The new socket is one of those very flush types meaning the back of it is quite fat (reason for new backbox).
I did sleeve all of the earth cables and check for damage on all the insulation.
With the socket not connected to the backbox in any way it does work fine, and wont trip the RCD when you plug things into it and turn them on.

 

[shaemoan]

Yes I did have to drill new screw holes. When drilling I didn't make it through to the other side of the breeze block. The screws used were only 35mm which is defiantly less than the depth of the holes.

 

[PrenticeBoyofDerry]

Okay, try taking socket plate off and connecting conductors as my edit.
All lives together
All neutrals together
All earths together but not connected to back box.
Then energise and hopefully no trips.
Then attach earth link to backbox and see what happens, if it trips the backbox is picking up an earth-leakage, possible as Flyingsparks has pointed out, you have may have damaged a conductor sinking the deeper box. is there a socket on the reverse side of wall?

If t does not trip, I would try another socket plate.

 

[shaemoan]

I'll give what you suggest with taking the socket off a go, and let you know the results. The other side of the wall is the exterior brickwork. I've no reason to suspect there is any cabling that runs inside the wall cavity.

 

[PrenticeBoyofDerry]

I look forward to your reply, we cannot rule out a faulty socket plate. I had a similar issue with a eurolite metallic switch plate.

 

[deadshort]

Hi, Can I ask is this a conduit job?

Regards,

DS

 

[flyingsparks]

Did you drill any holes to fix the back box to the wall? Or did you use longer screws? If there was another cable behind the back biz and it got damaged, when earthing the box it could cause this to happen

That was my next question!

Beat you to it..

 

[shaemoan]

Well I tried it with no socket and success. A fresh socket is now on and fully attached and no tripping. Looks like its solved.
Thanks everyone for your help

 

[PrenticeBoyofDerry]

Well I tried it with no socket and success. A fresh socket is now on and fully attached and no tripping. Looks like its solved.
Thanks everyone for your help

Happy to help!