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Earthing metal sockets?

Postby Bluto » Mon Aug 18, 2008 2:08 am

Hello, can anyone help please? I've asked at several DIY stores and can't seem to get an answer? :? I recently bought some brass-effect, 13A double pole, 2 gang socket faceplates, which I intended to use to replace the white plastic versions on the 5 sockets in my dining room. Prior to carrying out any work, I tested each of the 5 original sockets with a 3 LED socket tester and each indicated that it was working fine and set up correctly. However, when I opened up the sockets to start replacing the faceplates, I found that none of them were earthed to the back of the metal knockout boxes. :shock: Is this correct? Is it because the faceplates were plastic? I also wondered if it might be because of my meter set-up, which contains a 100A 30mA RCD protected circuit breaker, which I know works because after some recent problems with my boiler, the breaker kicked in even before the boiler's 2A fuse had chance to blow? Any pointers would be much appreciated. :oops:
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Postby kbrownie » Mon Aug 18, 2008 12:01 pm

The mains earth should be connected to the face plate and the metal backbox will be earthed via the metal machine screws used to fix plate on to metal backbox. If the backboxes where plastic ie dry-lining ones the face plate should be earthed but no need to earth backbox.
I always earth both the face plate and the metal backbox to each other.
This should make sure there is always a good connection, some don't but I prefer to do it that way.
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Postby ericmark » Mon Aug 18, 2008 1:41 pm

It is common to rely on the mounting screws to connect the earth between back box and socket.

Postby sparx » Tue Aug 19, 2008 6:38 pm

Hi Bluto,

You won't get an answer from a DIY shop assistant, they are not qualified to answer and so are discouraged from doing so in case they mislead some one & the store gets sued!

I agree with the others, the wiring should go to the face plate whether its plastic or metal clad since it is the earth pin that needs connecting plus metal plate if fitted.
As for 'pigtail' earth to back box, again only required if system of wiring uses metal conduit for it's earth, nowadays only found on older houses, usually local authority owned.
for those with the 'big red book' to look at 17th ed. regs 543.2.2(vi),
543.2.7 apply,

personally I don't fit 'pigtails' into an already crowded box,
regards SPARX
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Postby Bluto » Tue Aug 19, 2008 11:55 pm

Thanks everyone, this info is extremely useful and just what I was after. This has been my 1st outing on diydoctor and I'm well impressed, I'm going to see if I can maybe help someone else out now with one of their problems and return the favour. Best wishes, Bluto.
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Postby TOPSPARK » Wed Aug 20, 2008 9:15 pm

When installing metal face plates on the back of these is an earthing connection and you should take a flying earth from the face plate to the backbox so if the socket is taken off for any reason the metalwork is still earthed in his reply sparx should've pointed this out as if there is a fault whilst disconnected from the back box the face plate is still earthed.
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