Never come accross this sort of cable before...

[ashleycowx]

Hey all,

Was working on a pretty new build the other day, not sure what this cable is though, never really come across it before, its all wrapped in 1 sheath, then has 1 main line conductor, 4 non sheathed earth conductors and about 10 seperate neutral cables all sheathed separately...

Haven't got a pic of the earth but these are the neutrals and line...

 

[Sidewinder]

You would not normally as it is not a recognised cable type under BS7671, it cannot "officially" be used instead of SWA as not all live conductors are enclosed by an earthed metallic sheath.

It is called split concentric.

I did post the BS no for it recently, but I can't recall it off the top of my head.

If it is used in an application that requires an earthed metallic outer then it would be a C2 on a PIR IMHO.

 

[ashleycowx]

Hey

Ah Split concentric, taa v much..

This cable was used instead of meter tails to a main CU of the property (A 1 bed apartment of a 3 story block with the meter cabinet just the other side of the wall)..

 

[Andy™]

as above. it can be used, but its treated the same as T&E for mechanical protection etc

 

[kelvfoozinda]

Has an aluminium brown conductor though, probably not suitable to put straight into a main switch like that. Who fitted it?

 

[Andy™]

Has an aluminium brown conductor though

not always.

 

[binky]

You would not normally as it is not a recognised cable type under BS7671, it cannot "officially" be used instead of SWA as not all live conductors are enclosed by an earthed metallic sheath.It is called split concentric.

I did post the BS no for it recently, but I can't recall it off the top of my head.

If it is used in an application that requires an earthed metallic outer then it would be a C2 on a PIR IMHO.

why do DNOs use it for overhead supplies then? If you are correct sidey, I better re-wire my garage supply - I like the stuff as it's physically small and goes arond corners better, I always considered it a viable alternative to swa, if not quite as well protected as SWA. Not generally used due to price. Long argument coming ??? opcorn :^O

 

[Sidewinder]

Binky,

No argument, I have already posted the reasons why it is not suitable in place of SWA under BS7671, along with references to the relevant standards in other threads.

 

[NozSpark]

During my assessment I had a bit of DNO straight con ion the dashboard and my assessor and I got into a discussion about it.

I had been asked by an existing customer to connect some up that he had installed between his house and garage,, IIRC he had buried about 20M of it... I told him no chance and wished him luck trying to get someone to connect it. The main reasons being that it offered absolutely no mechanical protection (the same as split con)

Obviously straight con doesn't have enough conductors either for use as we are not allowed to use CNE in users installations without Home Office approval

 

[streetlighter]

It's a common find on old highway lighting installs to find split concentric cable used instead of SWA. Only tends to be found in board supply columns on new installations.

 

[Barx]

Did a load of rewires in bungalows in Hull where the meter cupboard wasn't even part of the main building, it was mounted in a wall over the path that was outside the front door. Why it was like that, I have no idea but these were done from meter to CU in split con' in a duct under path.

 

[Sidewinder]

Actually a recognised street lighting cable believe it or not!

It's just that we aren't "trusted" with it!

 

[Andy™]

problem with split con is that it doesnt have an earthed sheath - some of the sheath is neutral

and you cant use straight con because there is no earth, unless you use it as TNC. DNO can use it though

also, you cant use it for just L&N (& TT the end) because the neutral is not insulated, just sheathed

DNO use it all the time though. ive got a bit of 3c35 ali core that was an offcut from a job i was on a few weeks ago, although its not use use to me (its only 2mtr long anyway)

 

[binky]

I have to say I rarely use split con, and then it has never been buried, where I would only consider it if in conduit of some other sort of mechanical protection. I tend to use it at highish levels up walls to minimise visual impact, such as when feeding new supply to upstairs flats. Places where mechanical / vermin damage is unlikely. I was however under the impression that it was acceptable as swop for SWA having seen DNO use it so much, but always had nagging doubt about that as DNOs are weird

. Will return to SWA for all future jobs.