[quote author=JerryD link=1098546631/15#20 date=1099090875]but 2/3 of 32 amps is 21.33 amps, still more than the 20 amp rating of the cable. How is this allowed? [/quote]
I want to put this to rest
but to awnser your question, ring mains are an exception where the IEE regulations set out the maxium floor area surved, the type and size of cable that can be used, and maxium cable length
This allows a ring main of 32A using 2.5mm Twin+Earth Cable + 100M of Cable in total.
You could as an alternative have a Radial of 50m of 2.5mm T+E on a 20A CC
Or Radial of 100m with 4mm Twin Cable, with a CB rated at 32A..