Normally I wouldn't see the need to earth a UB but in this case I'm
running some cables through it. I'm planning to use a bit of plastic
pipe in the hole to prevent damage to the wire but wonder if I should
earth the steel as well.

If so what is the best way to connect the earth wire to the steel? The
steel is coated in a couple of layers of intumescent paint for fire
protection.

Fash

Fash wrote:

Normally I wouldn't see the need to earth a UB but in this case I'm
running some cables through it. I'm planning to use a bit of plastic
pipe in the hole to prevent damage to the wire but wonder if I should
earth the steel as well.

The beam is not an exposed-conductive-part, probably on two counts: (a)
it's not part of the electrical installation and (b) it will probably be
enclosed so it can't be touched. Therefore it does not need earthing.

However it may need bonding. If the steel is in contact with the ground
it will count as an extraneous-conductive-part and will need main
bonding (10 mm^2, usually) - as will any extensive structural steelwork
built off the ground, whether accessible or not. This won't apply if
the UB is just used as a horizontal beam or lintel to bridge an opening
and sits on masonry well off the ground.

If so what is the best way to connect the earth wire to the steel? The
steel is coated in a couple of layers of intumescent paint for fire
protection.

(If required) provide a suitable threaded stud on the steelwork, (M10
say) - this could be welded on or could be screwed into a tapped hole
and secured by locknuts. Crimp a round lug to the earth wire, sized to
match both wire and stud sizes and fasten securely to stud using a lock
washer, nyloc nut or locknut etc. to ensure it won't come undone.
(Connection to remain accessible for inspection and to be labelled in
the usual way.)

--
Andy

"Andy Wade"

=== Clip..

The beam is not an exposed-conductive-part, probably on two counts: (a)
it's not part of the electrical installation and (b) it will probably be
enclosed so it can't be touched. Therefore it does not need earthing.


==== Clip

--
Andy

Hmm interesting... So when using Galvanised Capping ...

http://www.tlc-direct.co.uk/Products/SC1.html

Do I need to earth the capping?

I suppose it could be classed as part of the electrical installation.

Thanks,
Roy

RzB wrote:

Hmm interesting... So when using Galvanised Capping ...
[...]
Do I need to earth the capping?

No - assuming T&E cable, properly installed.

I suppose it could be classed as part of the electrical installation.

It is part of the electrical installation but reg. 471-09-04 states that
the use of cable with a non-metallic sheath - i.e. PVC twin & earth - is
deemed to provide protection against shock for both direct and indirect
contact. Thus capping is not an exposed-conductive-part since it is
effectively deemed unable to become live in the event of a fault.
Therefore it doesn't need to be earthed, QED.

--
Andy

Hmm interesting... So when using Galvanised Capping ...
[...]
Do I need to earth the capping?

No - assuming T&E cable, properly installed.

I suppose it could be classed as part of the electrical installation.

It is part of the electrical installation but reg. 471-09-04 states that
the use of cable with a non-metallic sheath - i.e. PVC twin & earth - is
deemed to provide protection against shock for both direct and indirect
contact. Thus capping is not an exposed-conductive-part since it is
effectively deemed unable to become live in the event of a fault.
Therefore it doesn't need to be earthed, QED.

--
Andy

Yes - but I guess the time when it might become live is when someone
drills through it, and the cable it's supposed to be protecting. Mind you,
I guess they would have to be pretty determined to get through steel
with a masonry bit!

Thanks,
Roy

RzB wrote:

Yes - but I guess the time when it might become live is when someone
drills through it, and the cable it's supposed to be protecting. Mind you,
I guess they would have to be pretty determined to get through steel
with a masonry bit!

Yes but capping isn't considered to be protection for the cable, other
than during plastering operations, so it should only be used in the
defined safe zones. Everyone is of course fully aware of these zones
and no-one would ever think of drilling in one...

If you want better protection, and/or want your cables to roam free,
use earthed steel conduit or put the cables 50 mm deep.

--
Andy

"Andy Wade" wrote in message
...
RzB wrote:

Yes - but I guess the time when it might become live is when someone
drills through it, and the cable it's supposed to be protecting. Mind
you,
I guess they would have to be pretty determined to get through steel
with a masonry bit!

Yes but capping isn't considered to be protection for the cable, other
than during plastering operations, so it should only be used in the
defined safe zones. Everyone is of course fully aware of these zones and
no-one would ever think of drilling in one...

If you want better protection, and/or want your cables to roam free, use
earthed steel conduit or put the cables 50 mm deep.

--
Andy

I have a situation where I am taking cable at right angles
to a "connection" point, but that connection point will not be
visible. Behind kitchen floor cabinet. So I have to protect the cable.

I thought capping was a suitable alternative to conduit.
I read 522.06.06 (iii) and thought that capping would provide
the necessary alternative mechanical protection to conduit.

Is that not a generally accepted view?

Is steel conduit thicker than capping perhaps?

Can't say that I like doing this at all - but in this case It's a bit
awkward to avoid. Hmmm...

Many thanks for your help,
Roy

RzB wrote:

I have a situation where I am taking cable at right angles
to a "connection" point, but that connection point will not be
visible. Behind kitchen floor cabinet. So I have to protect the cable.

I thought capping was a suitable alternative to conduit.
I read 522.06.06 (iii) and thought that capping would provide
the necessary alternative mechanical protection to conduit.

Is that not a generally accepted view?

Is steel conduit thicker than capping perhaps?

Hmm, interesting question. The regulation does specifically mention
"conduit, trunking or ducting satisfying the requirements [...] for a
[circuit] protective conductor" for the circuit concerned. Capping is
certainly not any of these things, and is very much thinner than the
walls of normal conduit tube, or standard metal trunking. The official
view, therefore would undoubtedly be that earthed capping would not
comply. Nevertheless for the smaller sizes of T&E it almost certainly
would meet the CSA requirements for a CPC, so you could argue that it
would comply with the /spirit/ of 522-06-06. Then you have the issue of
how you make the earth connection - soldering, probably. I think I'll
leave you on your own on this one though...

Can't say that I like doing this at all - but in this case It's a bit
awkward to avoid. Hmmm...

As it's behind a cupboard, could it go on the surface (in PVC
mini-trunking, perhaps)?

--
Andy

"Andy Wade" wrote in message

Hmm, interesting question. The regulation does specifically mention
"conduit, trunking or ducting satisfying the requirements [...] for a
[circuit] protective conductor" for the circuit concerned. Capping is
certainly not any of these things, and is very much thinner than the walls
of normal conduit tube, or standard metal trunking. The official view,
therefore would undoubtedly be that earthed capping would not comply.
Nevertheless for the smaller sizes of T&E it almost certainly would meet
the CSA requirements for a CPC, so you could argue that it would comply
with the /spirit/ of 522-06-06. Then you have the issue of how you make
the earth connection - soldering, probably. I think I'll leave you on
your own on this one though...

I bought some capping today - as you say it's far to thin to give the
required
protection. Back to the drawing board.. Probably have to use conduit.


Can't say that I like doing this at all - but in this case It's a bit
awkward to avoid. Hmmm...

As it's behind a cupboard, could it go on the surface (in PVC
mini-trunking, perhaps)?

No no, I didn't explain myself properly...

The connection point is behind a kitchen floor unit.
From there the cable needs to go up the wall to the ceiling.
So once it's above the worksurface it's vunerable...

Many thanks for your advice,
Roy





--
Andy