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Old July 15th 10, 03:40 PM posted to uk.d-i-y
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Default Discussion - Earthing a ring main 13A socket metal back-box

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




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Old July 15th 10, 04:04 PM posted to uk.d-i-y
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Default Discussion - Earthing a ring main 13A socket metal back-box


"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


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Old July 15th 10, 04:37 PM posted to uk.d-i-y
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Default Discussion - Earthing a ring main 13A socket metal back-box

On 15 July, 15:40, "Spike" wrote:
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


I also use method 1, simply because the backbox terminal is rather
crude.
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Old July 15th 10, 04:54 PM posted to uk.d-i-y
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Default Discussion - Earthing a ring main 13A socket metal back-box

dom wrote:

I also use method 1, simply because the backbox terminal
is rather crude.


The back-boxes I usually buy have a nice, brass tunnel terminal.

So there's no code of practice that specifies exactly how the back-box earth
should be connected?

--
Spike


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Old July 15th 10, 06:06 PM posted to uk.d-i-y
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Default Discussion - Earthing a ring main 13A socket metal back-box



"Spike" wrote in message
...

So there's no code of practice that specifies exactly how the back-box
earth should be connected?
Spike

Correct, because as was stated in the first reply there is normally no
requirement to earth the back box.

Regards
Bruce



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Old July 15th 10, 06:18 PM posted to uk.d-i-y
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Default Discussion - Earthing a ring main 13A socket metal back-box

BruceB wrote:


"Spike" wrote in message
...

So there's no code of practice that specifies exactly how the back-box
earth should be connected?
Spike

Correct, because as was stated in the first reply there is normally no
requirement to earth the back box.

Regards
Bruce



which is how you get a nice shock off the screws used to connect the
front plate to the back box.

Are you serious?
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Old July 15th 10, 06:46 PM posted to uk.d-i-y
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Default Discussion - Earthing a ring main 13A socket metal back-box

The Natural Philosopher
wibbled on Thursday 15 July 2010 18:18

BruceB wrote:


"Spike" wrote in message
...

So there's no code of practice that specifies exactly how the back-box
earth should be connected?
Spike

Correct, because as was stated in the first reply there is normally no
requirement to earth the back box.

Regards
Bruce



which is how you get a nice shock off the screws used to connect the
front plate to the back box.

Are you serious?


With the caveat of there being at least one fixed lug, he's right.
Accessories usually have earthed metal rings in the screwholes.

Personally I do run a fly to the backbox even though it isn't strictly
necessary in my case, because it takes about 30 seconds extra effort.

--
Tim Watts

Managers, politicians and environmentalists: Nature's carbon buffer.

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Old July 15th 10, 08:36 PM posted to uk.d-i-y
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Default Discussion - Earthing a ring main 13A socket metal back-box



"Tim Watts" wrote in message
...
The Natural Philosopher
wibbled on Thursday 15 July 2010 18:18


Personally I do run a fly to the backbox even though it isn't strictly
necessary in my case, because it takes about 30 seconds extra effort.

--

I would not criticise anyone who does normally run an extra wire to the back
box, many were trained that way. I normally do not run one because I take
the view an extra wire is just one more thing to go wrong, come loose and
cause trouble.
Regards
Bruce

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Old July 15th 10, 10:46 PM posted to uk.d-i-y
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Default Discussion - Earthing a ring main 13A socket metal back-box


"The Natural Philosopher" wrote in message
...
BruceB wrote:


"Spike" wrote in message
...

So there's no code of practice that specifies exactly how the back-box
earth should be connected?
Spike

Correct, because as was stated in the first reply there is normally no
requirement to earth the back box.

Regards
Bruce



which is how you get a nice shock off the screws used to connect the front
plate to the back box.

Are you serious?


http://www.gtectraining.co.uk/images/back%20boxes.pdf

is the best link I can find.

Cheers

Adam


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Old July 16th 10, 03:56 AM posted to uk.d-i-y
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Default Discussion - Earthing a ring main 13A socket metal back-box

On 15 July, 22:46, "ARWadsworth"
wrote:
"The Natural Philosopher" wrote in ...



BruceB wrote:


"Spike" wrote in message
...


So there's no code of practice that specifies exactly how the back-box
earth should be connected?
Spike


Correct, because as was stated in the first reply there is normally no
requirement to earth the back box.


Regards
Bruce


which is how you get a nice shock off the screws used to connect the front
plate to the back box.


Are you serious?


http://www.gtectraining.co.uk/images/back%20boxes.pdf

is the best link I can find.

Cheers

Adam


Thanks, very useful.


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