Split concentric submains

[kevben]

I am currently on a big flat development project (old high school being converted to 50 flats, plus a 3 phase landlord supply). I had planned on installing 25mm 3core SWA for all flat submains as the Flats are all Electric with no Gas.
However, i am now considering installing 25mm or 35mm split concentric cable as the installation method would not require RCD protection.
It seems to me to be an easier option when it comes to termination at both: the supply Main Fuse (installed via trunking at the Bemco Cupboard) & at the Flat Consumer Unit.
The area that has been designated for the Bemco Cupboard (for all 50 x Flats etc) is extremely small, hence the potential option of installing split concentric cable versus SWA.
I have come across this method of submain installation on many occasions but have i never personally installed it.

I would appreciate any advice regarding using split concentric cable & also the current capacity of such cable (some flats will be approximately 120m cable lengths).

Thanks - KevBen

 

[Knobhead]

Now you're taking the ****!! lol!!!

Am I!
Have you ever got your hands on genuine DNO concentric cable?

It's as tough as old boots!

 

[Knobhead]

I didn't say it wasn't, but i wouldn't use any unarmoured cable in a direct burial situation, this cable is far better installed in a Duct...

It's not for direct burial, I thought we had established the fact.

It seems not.

 

[Knobhead]

We’ll continue the argument tomorrow. I need to take my medication at the moment, otherwise there will no further arguments.

 

[Rockingit]

Pretty sure they don't produce a concentric cable purely for the DNO's, that would cost the DNO's an arm and a leg for special cable....

Last DNO concentric for TN-C-S that I saw had a solid Aluminium live core, and a copper spiral Neutral. I can't see this as being commonplace, surely?

Oh, and it was ducted.