I have 6mm T&E in steel conduit going to a cooker unit which is no longer used. Also in the conduit is a 2.5mm T&E, also not used. I intend to use the 6mm for kitchen wiring with a design current of 36A. Kevins cable calculator advises the 6mm is good up 38A but it appears a bit marginal (especially since I was going to protect with a 40A RCD). Is it permissible to parallel up the 6mm and the 2.5mm at both ends.