There've been a few posts regarding fusing down when going from one cable size to a smaller one. How is one supposed to do this when going from 6mm to 4mm, since the latter is good for 32A and I haven't seen a normal FCU of this size. Reaons for asking is that I've got a couple of rooms of my house on a 4mm radial. However the rooms are (as the cable runs) about 15m away from the CU, so I ran the 15m section of cable to the first branch in 6mm, then did all the smaller sections in 4mm. The circuit is on a 32MCB at the CU, so everything would be fine by the regs if it was all in 4mm. But... am I still supposed to insert a fuse at the point where the 6mm changes to 4mm?