metal capping not needed according to 17th

[Des 56]

Although we don't use it here I know what capping is for. I just can't work out what metal capping would be for at all though, it just seems pointless.

How dare you suggest such a thing !
Just wait a while and I will rack my brain to think of one!

Mmmmmmmmmmmmmm
Still thinking

Mmmmmm
No,sorry can't think of anything (however trivial the anything may be)

I think you have just sussed out that some of the means of protection that could be afforded gets muddled up by designers who believe myths rather than how to comply,now where's that pot of paint gone

 

[Pete999]

Hillbilies, that is

Showing your age, I expected lots of comments, like whats he on about.

 

[SPARTYKUS]

Although we don't use it here I know what capping is for. I just can't work out what metal capping would be for at all though, it just seems pointless.

Answer in post 64. And then again in 77.

 

[Gavin A]

So again, what's the point of metal capping, other than to waste money on it?

if you bond it to earth then it becomes an earthed metallic covering as per 522.6.101 (i).

If you don't bond it to earth then it's as much use as a chocolate fireguard, certainly doesn't class as mechanical protection against nail penetration, only protection by sending the fault current down the earth path (and probably tripping the MCB) rather than through the body of the numbnuts who's just banged a nail into the cable, or anyone else who happened to come along at a later date and touch the nail and a radiator or something at the same time.

 

[Gavin A]

I'm a little surprised to find I'm the first to make that point on page 8 of this thread.

The regulation for mechanical protection is 522.6.101 (iv), the 2 things (mechanical protection and earthed metallic covering) are different classes of protection within the same regulation for protection of cables buried under 50mm from the surface, and can be applied instead of an RCD (unless that's needed for other reasons) and / or when not running cables in safe zones.

(ps that's from the BGB, haven't got the yellow version yet)

 

[Anthony S]

I'm a little surprised to find I'm the first to make that point on page 8 of this thread.

The regulation for mechanical protection is 522.6.101 (iv), the 2 things (mechanical protection and earthed metallic covering) are different classes of protection within the same regulation for protection of cables buried under 50mm from the surface, and can be applied instead of an RCD (unless that's needed for other reasons) and / or when not running cables in safe zones.

(ps that's from the BGB, haven't got the yellow version yet)

I was thinking of conduit for some reason that's why I've edited.

But I think the metallic covering your talking about is refering to the cable ie s.w.a and not capping.

 

[123]

if you bond it to earth then it becomes an earthed metallic covering as per 522.6.101 (i).

If you don't bond it to earth then it's as much use as a chocolate fireguard, certainly doesn't class as mechanical protection against nail penetration, only protection by sending the fault current down the earth path (and probably tripping the MCB) rather than through the body of the numbnuts who's just banged a nail into the cable, or anyone else who happened to come along at a later date and touch the nail and a radiator or something at the same time.

Well that's entirely different as I wasn't aware it could be used like that.

We don't use capping here, its generally 20mm conduit although oval can be used. To the best of my knowledge no wholesalers stock capping, be it plastic or metal.

 

[Gavin A]

I was thinking of conduit for some reason that's why I've edited.

But I think the metallic covering your talking about is refering to the cable ie s.w.a and not capping.

hmm actually, looks like you're right with that regulation as all the BS's referenced relate to SWA or similar. I'm sure it complies with one of 1,2,3 of that regulation for earthed metal conduit, trunks, ducting etc. Can't see why it wouldn't as long as the capping was equivalent to the CSA of the CPC, but I'm not forking out £100 or so for mutiple BS regulations to see exactly what they say.

It's possible that technically it doesn't comply with those british standards though, but that's how we've used it on occasions where we can't use a 30mA RCD due to the leakage current of inverters. Can't see why there'd be a need to try to have to channel so far into the brick / block to get full conduit in when it only needs protecting from one direction, and isn't relying on mechanical protection.