"Spike" wrote in message
...
It seems that the accepted method of earthing the metal back-box when
wiring
a ring main socket is to terminate the two T&E cable earth cores (suitably
sleeved Gn/Y) into the 13A socket earth terminal, and then to run a
separate
earth wire from the 13A socket earth terminal back to the earth terminal
on
the metal back-box.

I don't know if it is mandatory to specifically wire the earths in this
way,
or not. I have been unable to find anything conclusive on the Internet,
or
in the IEE 17th Edition Wiring Regulations.

In the past I have used this alternative procedu

Sleeve the first section of the two T&E cable earth cores (Gn/Y) and take
them directly to the earth terminal on the metal back-box. Do NOT cut the
earth cores - instead fold them back on themselves, so they enter the
back-box earth terminal doubled-over. Now sleeve the trailing ends of the
two T&E cable earth cores (Gn/Y) and connect them into the 13A socket
earth
terminal. The T&E cable earth cores remain continuous and uncut from
where
they exit the stripped T&E cable, all the way to the 13A socket earth
terminal, but they pick up the back-box earth terminal on the way.

My thoughts on this method a

1. The metal back-box would always be earthed, even if someone
disconnected and removed the 13A socket.

2. If the earth wires became loose and fell out of the 13A socket earth
terminal, the continuity of the earth would remain whilst the 13A socket
was
screwed into place on the metal back-box.

3. If the earth wires became loose and fell out of the metal back-box
earth terminal, the13A socket would still be earthed, as the earth cores
are
continuous (uncut).

4. This wiring method does make the earth core wiring tidy and more
compact. It also avoids the problem of terminating three earth cores into
one earth terminal on the 13A socket (although I accept that many 13A
sockets now have two earth terminals). IMO, three cores into one terminal
is a recipe for a loose core.

The only downside I can see would be if the earth terminal on the metal
back-box was a bit crude and behaved more like a guillotine, cutting
through
the earth cores.

Is there any reason not to wire the earth in this manner?

Any thoughts, comments, criticisms anyone?

--
Spike

Hi

The earthing of back boxes is not mandatory if there is at least one fixed
lug.

However, if you are going to do it, then either of your methods are fine.
When I have to to earth the back box I use method 1 as it is a) faster and
b) easier to split the earth if required for testing/ fault finding etc.

I have also frequently encountered a 3rd method. Which is to use just one of
the cpcs folded over in the manner you suggested.

Cheers

Adam