Earthing bathroom light

[Nathan Critchlow-Watton]

I know this query has come up lots of times, but I can't find an answer to the same situation!

I've re-wired the bathroom; I now have

Central light, running to switch outside bathroom. From light fitting,

3-core and earth runs to triple-pole isolator (metal back box) then to humidistat fan.

Shaver socket, with isolating transformer (also in metal back box) connected to lighting circuit under floor via junction box

Lamp over the sink ("correct" bathroom type), cable run from lighting junction box under the floor.

All of the above in either zone 2 or 3.

All pipework etc. connected equipotentially with 10mm earth cable.

Apart from connecting up earth in the T&E to back box, light fittings etc., do I need to run a separate earth from/to anywhere else?! I was confused by the Mike Lawrence book which shows a separate earth (?4mm) running to the equipotential earthing from the back of a socket.

Thanks very much, Nathan

[David Hansen]

On 21 Feb 2006 03:15:13 -0800 someone who may be "Nathan Critchlow-Watton" wrote this:-

You should really run a supplementary bonding conductor to the earth terminal of the transformer, though you will probably only get it into the terminal by removing some of the "strands".

If the lights are Class I you should connect a supplementary bonding conductor to their earth terminals.

Sockets in a bathroom? What sort of sockets?

The thread, "Elecric shower blown fuse" refers to a fairly well known diagram of supplementary bonding and extracts from a book. Have you studied that? Do you have any questions on it?

[Owain]

Yup, the socket back boxes etc need to be equipotentially bonded to the pipes. If everything's on the one circuit a single link from one back box or junction box to the pipe bonding should be adequate.

The purpose of this is to ensure the back boxes etc are at the same potential as the pipes, not to earth the pipes.

Owain