Best way to extend an incoming supply

[Southern Spark]

I am starting a rewire of a 4 bed maissonette next week. The meter and original c/u is by the front entrance, but the client wants it moved up to the first floor, which will then be near his front door. I want to keep the supply C.S.A at 25 mm, and obviously I will be incorporating a switched fuse to protect the supply, but I was wondering what is the best type of cable to use... the overall length of run is about 15 - 20 m, it will be run under floor boards for some of the run and coming up the wall in a cupboard. Is it ok to use normal tails for this?? I have never seen it done before like this. In the past I have used 16mm T and E, but like i say, there is a lot of heavy loads on the circuits, so I would like to keep it at 25mm, thanks.

 

[telectrix]

you could use 16mm xlpe SWA.

 

[Guest123]

Split con maybe an option also. It must be treated in the same manner as T&E with regard to installation practices and possible RCD protection etc.

 

[Welchyboy]

I have done this too recently, EDF moved meter from cu approx 20m away, SWA for me was too stiff for some of the route so i fed 25mm tails from 80A switch/fuse unit and 16mm earth and 10mm earth (to bring to bonding back to the new origin rather than the c.u.)
I used 32mm galv conduit with an earth clamp at the points the cable needed to be concealed within the wall, make sure if your running through joists they are >50mm from top and bottom and should be fine, abviously cable tie the single cores and earth together so they are basically a big twin and earth

P.S. 20m of 25mm singles + 16mm earth + 10mm earth = ££££

 

[Southern Spark]

Thanks for the responses so far guys... I was thinking split concentric myself, would this be alright. I have not installed it before. Is it not classed as singularly insulated? I like the sound of bringing it up in a bit of 32 mm galv with a nice set into the bottom of the board. What is split con like to work with? is it easy to run through joists??? thanks a lot guys... I love this place

 

[Southern Spark]

oh, one other thing, what is the price like on split con? compared to armoured/ tails etc

 

[SPARTYKUS]

I thought split con was dodgy for domestic (but cannot back this up with a definitive reg or post, just remember sommat) - as its not really 'meant' for running through a house, so to speak. Something to do with BS numbers, and it being used by the distributors who have different regulations to adhere to...

I am quite happy to be slapped about the head now by people of much greater knowledge ....

fix bayonets!

 

[mogga]

split conn may work out cheaper than tails and deffo cheaper than SWA its a dawdle to work with so long as its treated with respect its NOT SWA and doesnt like scufing to much

 

[Knobhead]

Only used it a couple of times in an office block. 35mm feeding about 6 sub boards. After years of mauling SWA’s around I thought I has in heaven using it.

Just a word of warning when you cut the outer serving don’t go to deep otherwise you’ll be slicing the neutral insulation. If you ring the cable at the point you want the serving to end you will hear if your going to deep as there is a melinex binder around the N & E conductors, it crackles if you cut it.

Have fun!

 

[Engineer54]

There are pukka heatshrink trouser crutch sealing breakout accessories available for concentric cables, although you can if competent, use a standard 3 core heatshrink trouser breakout. I would always use these breakout accessories they seal the cable and give a professional finish to the job. You can use amalgamating tape, but unless you know how to work it, it can end up looking like a pig's ear of a termination. I would always use appropriately coloured heatshrink sleeving on both the neutral and the earth conductors.

A little more expense and a little more time i know, but well worth the effort in the finished terminations. Not really that keen on using concentric stuff mind, much prefer SWA route myself!!

 

[caldymark]

I have done this too recently, EDF moved meter from cu approx 20m away, SWA for me was too stiff for some of the route so i fed 25mm tails from 80A switch/fuse unit and 16mm earth and 10mm earth (to bring to bonding back to the new origin rather than the c.u.)
I used 32mm galv conduit with an earth clamp at the points the cable needed to be concealed within the wall, make sure if your running through joists they are >50mm from top and bottom and should be fine, abviously cable tie the single cores and earth together so they are basically a big twin and earth

P.S. 20m of 25mm singles + 16mm earth + 10mm earth = ££££

I would be grateful for clarification of the above.
My consumer unit is to be moved across a double garage. Presently adjacent to the incoming supply and gas meter it is to be connected from the new DNO installed isolator using 10m long 25mm tails and 16mm earth. And yes I can confirm that it's costly.

My question is about the earth connection to the gas meter. Does this have to be run (in 10mm) from the new consumer unit location - another 10m of cable? Or can it be connected to the adjacent incomer where the 16mm for the consumer unit is connected - about 1.5m of cable.

Thanks and regards.

 

[Welchyboy]

Well i run my main bonds back to where the new incoming supply/switch fuse is now located as this now becomes the new origin of the supply (where, in the regs its supposed to be connected to), your consumer unit will no longer be at the origin.
in reality theres probably not an issue with running your bonds back to the new consumer unit, as long as they are all installed pukka, but it sounds like less work connecting them at the incoming supply

 

[Knobhead]

connected from the new DNO installed isolator using 10m long 25mm tails and 16mm earth. And yes I can confirm that it's costly.

That’s a NoNo, other lads will tell you better. You can’t run the tails for 10M

 

[Hawk81]

I would be grateful for clarification of the above.
My consumer unit is to be moved across a double garage. Presently adjacent to the incoming supply and gas meter it is to be connected from the new DNO installed isolator using 10m long 25mm tails and 16mm earth. And yes I can confirm that it's costly.

.

You must fit your own fuse on these tails. DNO fuse only covers tails up to 3 meters long. Rcd protection will probably also required depending on installation method

 

[caldymark]

Thanks Welchyboy I am now clear that the new origin of the supply will be at the start of the newly created sub-main. Also, thanks for the feedback Tony and Hawk81. Yes the installation will have a switch fuse, sorry I didn't mention it. I should have realised that writing "10 m tails" would sound alarm bells with competent persons.
Cheers.