Sizing mains tails

DanBrown · Mar 27, 2009

Can anyone shed a bit of light on correct sizing of mains tails...
I am always let to believe that all cables need to be protected by the correct size fuse...
So i know in a domestic that 25mm2 is the minimum permitted cable CSA and can take 114 Amps.
What happens in a commercial building for example and has a 300A service head??, according to OSG the closest to match 300A is 95mm2 CSA and that can only take 284A.. What is the correct size to use?

Thanks in advance guys..

bcm_spark · Mar 27, 2009

is it 100A per phase?

Spudnik · Mar 27, 2009

I would think that you have 100A per phase, so in which case 25mm tails and 16mm M.E. would be fine.

DanBrown · Mar 27, 2009

No, i actually meant 300A per phase

kung · Mar 27, 2009

Hi Dan
300a per phase is 35mm they will always fit these to anything from 100A to 300A and CT whole currant ! only time this changes is in some factories where they dont norm have meters they fit a small sub station near/next to building which is 400A and run 50mm into building for supply !
Regards
Kung.