How to treat this cable

[doni]

Each core is separated and is on the existing ring - 2.5mm?

Not sure of the effect on current carrying capacity due to being buried in concrete.

Untitled

• doni
• 21 Mar 2011
• 1

 

[RF Lighting]

What on earth is it?

Looks like it wants cutting off and replacing with some proper BASEC approved cable.

I'd be concerned about the rest of the installation too if that 'cable' and the state of the back box are anything to go by

 

[westie101]

It looks like some strange outer sheathing that has had singles pushed through it!

 

[JohnD]

shed supply?

 

[doni]

The flat was built in the mid 80's - top flat - concrete floor - the whole ring has been done in this stuff - feels like a hard rubber - each core is spearated. The cable goes under the concrete - about 2 inches below floor level.

I wish to break into the main - knocking out about four sockets and relocate four other somewhere else in 2.5mm, clipped to stud wall - away from insulation - so I know I don't have to worry about my work - just trying to calculate the effect of this stuff being buried in concrete.

 

[doni]

Looks like it wants cutting off and replacing with some proper BASEC approved cable.

I'd be concerned about the rest of the installation too if that 'cable' and the state of the back box are anything to go by

That'll be a hell of a lot of chasing up the walls to the loft to replace all of the cable. The back box looks like it has been broken like that at the bottom because the cable won't fit in the normal hole (it's too big)!

 

[ChrisRogers]

I've seen exactly the same cable in 1.5mm used in an extension.

I guess its the same as singles in conduit?

 

[doni]

OK - more generally then - what would be the correction to apply - if any to 2.5mm in concrete - I have the tables for cables laid in insulation and cables running together in groups, but don't know the effect for cable in concrete

 

[westie101]

If any help, there are no de-rating factors applied to DNO cables in concrete. We don't like them there and usually find someone else has happily surrounded them in concrete

 

[doni]

Thanks Westie.

I have just been searching on the internet and found that concrete had good thermal dissipation - so maybe there is no factor to apply.

 

[sparkydude]

that stuff is called pre wired conduit , saw it years ago in professional electrician magazine , like octoflex as it used to be known

nick

 

[sparkwright]

It's designed specially to go in concrete floors.

 

[Click-Sure]

Yep, its pretty rare! saw it on a HA job in Wolverhampton, one of those 'new' ideas that dissapeared pretty quickly! cant see anything wrong with it tho.

 

[1john]

Seen this around here in a council mainsonette (flat) a bit of a nightmare to get it into a knockout mind. I think I had to adapt a 6mm cable into a cooker switch but cant remember for sure. The ring final circuit was also wired in it too.

 

[ajrobb]

With the live conductors so far apart, I wonder if it has a higher current carrying capacity than PVC T+E?