On Monday, 5 April 2021 at 11:27:36 UTC+1, ARW wrote:
On 04/04/2021 14:20, Tricky Dicky wrote:




If you have loft insulation and the cables will run either across or through it you may have to uprate the cable to 1.5mm2 which make for a tighter fit.

Maybe not now we have LED lighting.

http://wiki.diyfaq.org.uk/index.php/Cables#Cable_Sizes

1.0mm T&E has a CCC of 16A so if we have to derate this by 50% it can
still be covered with a 6A MCB. Further say we then had to apply another
0.7 derating due to it been say 50deg then you still have 5.6A to play
with. That is 1.29kW. Now only if the OP has a load somewhere in that
region do you need to consider upping the cable size.

50 degrees sounds a bit high?

In practice the first floor lights will be less than 200W.

Length of run is no problem. So 1.0 is looking attractive.