External Meter tails Help

Power Ball · Nov 9, 2013

Hi Guys went to look at a friends house he has just bought, at some point the CU has been moved from just behind DNO board to 6 meters away using 10mm T&E as a temp feed loose cliped inside. The Outside cabinet has the meter head in with 25mm tails going to an isolater switch and the temp feed from that.

I would like to make this right for him so was looking to use SWA on the out side of the building 6 meters then into the back of the new CU both the cabinet and the CU are on the same wall just 6 Meters away

Firstly what size SWA do I need 25mm ?

or would I be better to use normal 25mm meter tails inside plastic conduit insted of swa ?

Any advise would be good I am Part P Quallified but done very little work like this and have just been recovering from a big operation I had 6 months ago so still not very active at the mo..

Thanks

Chas

telectrix · Nov 10, 2013

SWA for me. 25mm 3 core. gland into galv adaptable box below CU and feed tails through. ditto at isolator.

HandySparks · Nov 10, 2013

What's the earthing system?

SPARTYKUS · Nov 10, 2013

Or use 16.0mm Armoured as you'll probably need to fuse down for the supplier as its more than a few metres. 16 will take well over 80 Amps. Clipped or on tray/in free air.

or in a bath of liquid nitrogen.

Power Ball · Nov 10, 2013

HandySparks said:
What's the earthing system?

Hi
It is a TNC-S system but looking at calcs I think 16mm swa connected to a fused sw Isolator at dno end and terminate into a metal box at cu with tails into the CU, does this sound OK.

Power Ball · Nov 10, 2013

Should have said it is TNC-S earthing system, looking at calcs I think 16mm swa from a sw fused isolator at DNO end and terminate into a steel box and tails to cu ,,, or would it be safe to go streight into cu with swa,, which does not seam right or safe to me??

Thanks

Chas

HandySparks · Nov 10, 2013

If TN-C-S, then just a fused isolator at the supply end will be OK. You need to assess whether an 80A fuse and 16mm² SWA will be OK, which it will be in the majority of domestic situations, or whether you need to fit a 100A fuse and 25mm² cable. The size of the existing supplier's fuse may be a guide.

I wouldn't worry about trying to get any discrimination between the supplier's fuse and the additional one.

If the CU is metal, then obviously you can terminate directly into that. If plastic, terminate into a galv box positioned against the CU and just run the cores and bedding into the CU.