I have a shed that I'm proposing to run a spur out to from the house. I have identified a suitable socket on the ring main, and am going to run some armoured cable some 5m between the 2 buildings. I am going to put a fused 13a switch on the inside of the house wall, and the shed already has a fuse box and has been wired professionally. Will this be ok and safe? I am using a PC, a light and a 1 kilowatt oil filled radiator in the shed.