Hi Guys, Need advice on power supply to outbuilding which I'm planning to build shortly before building an extension and loft conversion on main house (inc full re-wire.) How do I go about calculating what I will need in terms of cable size and presumably a small secondary consumer unit? what about earth? The building will be around 30m from house, 40m from consumer unit. We would like to 'camp' in the outbuilding so we are out of the house and still onsite for the build which will mean a toilet and maybe some kind of water heating (presuming any domestic electric shower is a no go - maybe a 2kw water heater - not expecting anything other than a trickle for a shower) plus 1 or 2 electric heaters. And of course lighting and sockets. Outbuilding will be timber frame, fully insulated (50mm celotex floor, 50mm celotex +100mm rockwool walls & ceiling) and just under 30sqm footprint. I'll be digging a trench to connect to mains drainage and will dig a smaller trench within this to 750mm+ for a water pipe below frost level. somewhere above this in the trench will go a power cable and outdoor cat6 (recommended distances?) From a quick search cable cost for 40m is; 10mm - £3pm = £120 16mm - £5pm = £200 25mm - £7pm = £280 So in my eyes, thats no big deal just get what I need. As I said, temporary living accommodation, anti-frost heating, a small water heater if possible and then in the future, maybe a carpentry workshop or maybe a man cave with guest accommodation. We have planning approved, building control appointed and an electrician lined up but I'm a belt and braces kind of guy and would like to cover this myself. Any advice welcome! Let me know if you need a list of appliances that might be used?