capping

[Buzz-light-bulb]

Does anyone know anywhere in the regulations that it states I have to use capping to protect cables when embedded in plaster as I am currently on a rewire, it says in on site guide that if there's no rcd protection it does require metal earthed capping

 

[mark80]

Capping does not have to be used, it's only really to protect the cables from the plasterer when patching in. Plastic or metal capping offers no mechanical protection to the cables if the customer wants to drill a hole in the wrong place. Aslong as you are RCD protecting the cables then they require no additional mechanical protection.

Edit: are you not RCD protecting the cables within the wall? If not, why? As you are creating a hell of a task trying to provide earthed capping etc to protect the cables if not!

 

[telectrix]

capping is just to protect from plasterer damaging cables. not required when it's just a chase or dry lined. RCD is the best way to comply with 522.6.101.

 

[Buzz-light-bulb]

Yes I'm protecting with rcd sorry I forgot to input that

 

[kingeri]

You wouldn't earth metal capping! Don't confuse metal capping with providing earthed metal protection for a cable, they are two totally different things!

 

[telectrix]

as kingeri says. earthed metaillic protection is steel conduit, not tissue thin capping that won't stop a nail.

 

[DPG]

It's amazing the number of people that think that earthed metal capping is classed as protection. Daz

 

[Engineer54]

You could realistically say the same for SWA cable that's been imbedded in a wall or whatever. The SWA isn't going to stop a nail either, but it doesn't require RCD protection!!

 

[DPG]

Yep, you've got a point there Eng. Daz

 

[mark80]

I didn't mean to say capping, replying too quickly without thinking. TBH I don't think conduit would stop a drill bit going through if you were determined enough to put your picture there. Mind you, atleast the replacement cable would be easy to pull back down haha!

 

[MDJ]

Agree that capping is only for protection against the plasterers trowel, that said I always double cap with metal capping when doing a rewire, It was the way I was taught and to be honest 2 pieces of capping one on top of the other is quite tough to damage, seriously you try it.

 

[D Skelton]

Can't see the problem with using earthed metal capping so long as it could be confirmed that its copper equivalent csa was the same as or more than that required for that circuit. We use BS8436 cable which is essentially some T+E wrapped in some steel capping lol.

It's got nothing to do with whether or not the cable is protected from penetration by a nail or screw, it's got to do with whether or not there is an earth fault path other than the person hammering the nail into the wall and through the cable, which can withstand the fault current for any given duration.

The steel wire strands in an SWA don't protect the cable from damage, they earth anything slicing through it before it makes contact with one of the live conductors.

 

[DPG]

Can't see the problem with using earthed metal capping so long as it could be confirmed that its copper equivalent csa was the same as or more than that required for that circuit. We use BS8436 cable which is essentially some T+E wrapped in some steel capping lol.

It's got nothing to do with whether or not the cable is protected from penetration by a nail or screw, it's got to do with whether or not there is an earth fault path other than the person hammering the nail into the wall and through the cable, which can withstand the fault current for any given duration.

The steel wire strands in an SWA don't protect the cable from damage, they earth anything slicing through it before it makes contact with one of the live conductors.

I've just read the post where he says he is still protecting with an RCD. Apologies - I thought he was trying to avoid RCD protection. Daz

 

[mark80]

I don't see how whether earthing conduit or capping is feasible anyway, unless you welded the cable onto it, the joint surely must need to be accessible for inspection and testing purposes? If you earth the top of it, the joint will be under the floorboards. If you decide to earth it off the cable at the socket or switch, then surely you could create more danger if the cpc was then broken in the cable, leaving the metal conduit in the wall potentially live.

 

[D Skelton]

I have never done it so far, but if the situation ever arised where I needed to omit RCD protection for a cable hidden in a wall and for some reason couldn't use SWA, galv conduit or BS8436 then I wouldn't feel at all worried about using a couple of lengths of capping on top of each other, rivetted together and crimp connected to the cpc of that circuit.

This however is a far distance from steel capping your cable whilst mistakenly believing that it will offer the said cable some sort of protection.

 

[DPG]

Really?? Earthed capping to avoid RCD protection?? Daz

 

[D Skelton]

Really?? Earthed capping to avoid RCD protection?? Daz

Like I said, there are at least five other options available to me before I would choose that option. But, if I did have to choose that option (not that I ever would have to) then theoretically there is no problem with it at all.

 

[DPG]

I thought it would need to be 3mm steel ( or equivalent). 2 pieces of thin galv wouldn't be anywhere near equivalent of 3mm steel. Daz

 

[D Skelton]

I thought it would need to be 3mm steel ( or equivalent). 2 pieces of thin galv wouldn't be anywhere near equivalent of 3mm steel. Daz

Like I said, just like SWA, it isn't there to protect the cable, it is there to provide an earth fault path back to the point of origin if ever the cable was penetrated.

3mm steel wouldn't need to be earthed because that is there to stop the cable getting penetrated in the first place!

 

[DPG]

Yeah, I get that but we're talking about cables at a depth <50mm and no RCD. What about what the regs say about suitable protection? Daz