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Old February 12th 05, 07:03 PM
John Borrman
 
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Default Earthing Metal back boxes and matal face plates

Hi,
Just a quick question. Replacing lights and sockets with metal face plates.
Just have a question. I know you are meant to run an earth cable from the
plates to the back box. But some of them dont have a earth terminal on the
back box, so I was wondering, is it entirely essential if it is is there a
way around attaching the earth to the back box
Thanks

J



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Old February 12th 05, 07:13 PM
Andrew Chesters
 
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John Borrman wrote:
Hi,
Just a quick question. Replacing lights and sockets with metal face plates.
Just have a question. I know you are meant to run an earth cable from the
plates to the back box. But some of them dont have a earth terminal on the
back box, so I was wondering, is it entirely essential if it is is there a
way around attaching the earth to the back box
Thanks

J


OTT in my book, but the IEE say otherwise. (Wonder if they have
shares.... and other unworthy thoughts)

However on a practical note, crimp a ring on your stub of earth wire and
put that under the fixing screw.
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Old February 13th 05, 08:56 AM
John Borrman
 
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Yes, and if your back boxes haven't got an earth terminal they need
replacing.


Would it suffice under IEE regs as Andrew recomended to crimp a earth wire
to ring and connect this to the fixing screw? Its just that all walls have
been plastered and painted now.... cant face replacing all the face plates.

You can't rely on the earth provided by the faceplate screws

mike



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Old February 13th 05, 10:30 AM
mike ring
 
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"John Borrman" wrote in
:

Yes, and if your back boxes haven't got an earth terminal they need
replacing.


Would it suffice under IEE regs as Andrew recomended to crimp a earth
wire to ring and connect this to the fixing screw? Its just that all
walls have been plastered and painted now.... cant face replacing all
the face plates.


I'm not an expert, and I may have misunderstood his post, I took it to mean
that a good earth to the faceplate was enough.

But looking back, if he meant fabricate a good earth to the box, and
continue it to the faceplate, I'm sure that's ok.

(Can't see his post any more, me reader's thrown a wobbly, I must have hit
a wrong key by accident)

pikey mike
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Old February 13th 05, 10:59 AM
John Borrman
 
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Cheers for that, rather fabricate an earth than replace all the boxes....




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Old February 13th 05, 11:19 AM
Dave Stanton
 
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On Sun, 13 Feb 2005 08:56:03 +0000, John Borrman wrote:

Yes, and if your back boxes haven't got an earth terminal they need
replacing.


Would it suffice under IEE regs as Andrew recomended to crimp a earth wire
to ring and connect this to the fixing screw? Its just that all walls have
been plastered and painted now.... cant face replacing all the face
plates.

You can't rely on the earth provided by the faceplate screws

mike


I would add a corrugated washer between ring and metal of box to give it
some bite.

Dave

--
For what we are about to balls up may common sense prevent us doing it
again
in the future!!
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Old February 13th 05, 01:24 PM
Andy Wade
 
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John Borrman wrote:

Cheers for that, rather fabricate an earth than replace all the boxes....


IF we're talking about flush metal mounting boxes that are sunk into the
wall (i.e. not accessible when the wiring accessory is in place),

AND the wiring system is twin-and earth and, explicitly, is NOT MICC or
metal conduit, where the earthing is provided by the metal sheath of the
cable or the conduit, via the mounting box,

AND the metal face plates each have an earth terminal,

THEN it's OK to connect all the incoming earth wires to the faceplate
terminal and there's no specific requirement for a separate earth wire
to the back box. The box (which is not an exposed-conductive-part in
these circumstances) will be earthed via the accessory mounting screws.

--
Andy
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Old February 14th 05, 01:15 AM
Mike
 
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Default


"Andy Wade" wrote in message
...
John Borrman wrote:

Cheers for that, rather fabricate an earth than replace all the

boxes....

IF we're talking about flush metal mounting boxes that are sunk into the
wall (i.e. not accessible when the wiring accessory is in place),

AND the wiring system is twin-and earth and, explicitly, is NOT MICC or
metal conduit, where the earthing is provided by the metal sheath of the
cable or the conduit, via the mounting box,

AND the metal face plates each have an earth terminal,

THEN it's OK to connect all the incoming earth wires to the faceplate
terminal and there's no specific requirement for a separate earth wire
to the back box. The box (which is not an exposed-conductive-part in
these circumstances) will be earthed via the accessory mounting screws.



Andy - this sounds far too sensible for the IEE regs. Are you sure this is
correct as everybody else seems to think the wire is needed, including that
apprentices thing on TV a few weeks back.

That said, I've never put it in either as I think it has no useful purpose
and until Part P came along was allowed to argue so.


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Old February 14th 05, 01:49 AM
Andy Wade
 
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Mike wrote:

Andy - this sounds far too sensible for the IEE regs. Are you sure this is
correct as everybody else seems to think the wire is needed,


It's required in the circumstances where the earth (CPC) is supplied
_to_ the box first through metal conduit, etc. - otherwise I'll stand by
my interpretation.

including that apprentices thing on TV a few weeks back.


I saw that and it involved metalclad fittings and metal conduit. I
don't think the conduit was providing the CPC, but it and the boxes were
certainly accessible (exposed-conductive-parts) so needed to be reliably
earthed. Quite a different situation to what we're talking about here.

--
Andy
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Old February 14th 05, 08:03 PM
Mike
 
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"Andy Wade" wrote in message
...
Mike wrote:

Andy - this sounds far too sensible for the IEE regs. Are you sure this

is
correct as everybody else seems to think the wire is needed,


It's required in the circumstances where the earth (CPC) is supplied
_to_ the box first through metal conduit, etc. - otherwise I'll stand by
my interpretation.


Thanks. I'll refer the BCO to you if he complains :-)




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