Situation is garden summerhouse fed by own 16A RCBO in consumer unit in garage over 4mm2 (overkill !) SWA . At summerhouse this goes to sockets (no FCU) and to lights via FCU with 5A fuse. The lights are all LED so consuming minimal current From the searches I've done it would seem that is okay, but one website claims - "Outbuildings, Garages and Sheds are all required to have their own fuseboard or consumer unit under the BS7671 regulations". It doesn't say where the reg say that, does anyone know, or is this rubbish ?