Split concentric submains

Silly Sausage · Oct 27, 2013

543.4 refers to PEN conductors, split con is under discussion here.

addition:

543.4.7 because Earth would be disconnected.

Guest55 · Oct 27, 2013

hmm , getting warmer with this debate now ;-)

following on from tonys post ,

pvc concentric cable was indeed developed for use by the dno's as it is lighter and cheaper than swa , flexible in the cold , and can be worked on live fairly easily as you know the live core is in the centre of the cable , making stripping it back alot safer with the power on.

which all means its great for the dnos.

the issues i have with its general use in buildings wiring is that the neutral conductors are not afforded the same level of insulation and protection as the live.
and as the earth conductors are bare anyway , it wouldnt take much in the way of abuse before you start getting crappy ins. res. readings between N & E.

all things considered though , its good stuff but its applications must be selected carefully.

Knobhead · Oct 27, 2013

Biff, nail on head!

Split concentric is for post DNO termination, concentric pre termination.

Handled and terminated right, its excellent cable. I’d much rather work with a 25mm S/C than the equivalent SWA.

I took a piece of DNO concentric and put a 1KV test on it. It took seven good clouts with a 2Lb hammer for it to even start breaking down. Not very scientific I know, normal test methods for me.

Andy78 · Oct 27, 2013

Tony said:
Biff, nail on head!

Split concentric is for post DNO termination, concentric pre termination.

Handled and terminated right, its excellent cable. I’d much rather work with a 25mm S/C than the equivalent SWA.

I took a piece of DNO concentric and put a 1KV test on it. It took seven good clouts with a 2Lb hammer for it to even start breaking down. Not very scientific I know, normal test methods for me.

That'll do for me.
I first saw the durability of MI shown to me in this way. A live piece of 2L1.5 with a lamp attached and lit was pounded with a lump hammer on an anvil. Was flattened to about an inch wide before the cable failed.

tbs1983 · Oct 27, 2013

we use split con in my job on street lighting. we get a lot of neutral-earth faults with it. mostly dead shorts. Tend to use SWA as much as possible now on new installs & rewires as we find it a lot more reliable.

Knobhead · Oct 27, 2013

tbs1983 said:
we use split con in my job on street lighting. we get a lot of neutral-earth faults with it. mostly dead shorts. Tend to use SWA as much as possible now on new installs & rewires as we find it a lot more reliable.

Faults are mainly due to incorrect termination, I’ll guarantee it.

Rockingit · Oct 28, 2013

Never having terminated split-con or that I can recall, ever having seen it demonstrated, what is the correct/preferred method?

Rockingit · Oct 28, 2013

biff55 said:
the issues i have with its general use in buildings wiring is that the neutral conductors are not afforded the same level of insulation and protection as the live.

Apart from the obvious one of the live being itself 'protected' by N & E, I can't see how that really stacks up? You've a 7 stranded core covered in one layer of insulation, and a N of 7 x singles (or small stranded) all individually wrapped to produce the same csa - so on aggregate that's far more PVC covering the N than the L!