Aluminium/Copper Split Con

Does this help? https://www.elandcables.com/media/39051/aluminium-split-concentric-pvc-cable.pdf

   - Andy.

It is likely that 80A is the maximum you will get on a 25/16 concentric. What colour is the cutout? Some DNOs will only put a 100A fuse in the newer grey coloured cutouts. 


Regards,


Alan.

Thanks Andy, but unfortunately it is for 25mm2 Aluminium x 25mm2 Cu x 25mm2 Cu  whereas the cable I am looking for is 25mm2 Aluminium Live x 16mm2 Cu N and 25mm2 Cu Earth. Which suggests the max current will based on the 16mm Cu neutral (and Earth)?


Clive

Alan, the cut-out is a grey Henley Series 7 100A Type II b

(I'm thinking ahead re EVC)


Clive

Thanks Andy, but unfortunately it is for 25mm2 Aluminium x 25mm2 Cu x 25mm2 Cu  whereas the cable I am looking for is 25mm2 Aluminium Live x 16mm2 Cu N and 25mm2 Cu Earth.

Are you sure? Aluminium has a higher resistance than copper per mm² so it would seem rather a waste of copper to make the copper N the same c.s.a. as the aluminium line. The data sheet says for the 25mm nominal size (presumably c.s.a. of the Al line conductor) both L and N have a resistance of 1.2 Ohms/km - which suggests to me the Al is a size larger than the Cu.


  - Andy.

Are you sure? In “DNO speak” these are known as 1 core cables, and usually specified by the size and material of the phase conductor only. I would expect 25mm2 Al to have an insulated phase, covered 16mm2 Cu neutral and 16mm2 bare Cu earth. I would also expect to find two insulating packers, separating the neutral cores from the earths. A 35mm2 Al cable would have covered 25mm2 Cu neutral and 16mm2 bare Cu earth, plus two insulating packers. 


The grey cutout should be good for 100A. 


Regards,


Alan.

Just re-reading your original post, I may be able to explain the problem. With the red/black split concentric, the covered neutrals were black, but the two insulating fillers were also black. This has caused most a great deal of confusion, as attempting to strip a filler does not reveal any copper. 


Regards,


Alan.

Sorry Alan, my mistake there, a typo. The Red is 25 mm2 Aluminium and the Neutral is 16 mm2 Cu of seven strands with thin Black insulation and the 16 mm2 Earth 5 strands of Cu.  The outer sheath is embossed, from memory 25 x 16 x 16.  I will try and find the piece that the jointer gave me to add to my "cable collection" and check!  (It is quite a collection in fact, includes a piece of TAT-1 as well as the original mid 1800s transatlantic telegraphy submarine cable.) 


Our original service cable to the under the stairs cut-out, was PILC with an overall diameter of about 1 inch and I am guessing the two cores are either 7/0.064 or 7/0.080 - I will have to strip the end of a small piece that I also have and measure it!


Any ideas as to what the rating of those PILCs would be please?


Clive

I’ll have to check my cable tables later. I am still fairly confident two of your “conductors” nearest to the earths have no copper in them. If you look at the insulation on the phase and compare it to the neutrals, you can see why we usually call it “covered” rather than “insulated”. 


Regards,


Alan.

I found my small piece of split-con and the details are:-


Manufactured by Wessel. It has been embossed 2001 ALI/CU (This piece is not long enough to show anything else.)


The Centre Conductor is a single Aluminium 5.6 mm in diameter, with Red insulation giving an overall diameter of 7.6 mm. Equals 25 mm2.


There are 7 Black covered cores of 1.7 mm diameter Copper, with an overall diameter of 2.23 mm, Equals 16 mm2.


There are 4 (NOT 5 as I posted previously) bare Copper cores each 2.25 diameter. Equals 16 mm2.


Between the Neutral and Earth cores, there are two white polyester(?) fibre spacers. (Similar to bailer twine - there's a word from my farming past...)


I will try a post a photo tomorrow.

Clive