DIY Doctor UK DIY Forums

Hi guys I have just had a brick built shed/workshop/man cave. It is approx 50m from the house. I would like to add electric as I’m planing on have a fridge/freezer, tv, treadmill as well as about 9 sockets & 2 led tube lights installed. What would be the best setup in terms of size & type of cable? & would u suggest having a separate consumer unit? Any help would be greatly appreciated. Thanks

Its not as simple as you would have thought.
What you require depends on a variety of factors, for example what will you actually have, tools?, TV?, heater? not to mention the earthing arrangements.
Believe it or not fridges / freezers do draw a lot of current on start up. Also some freezers will not work in an out building (Too cold, seriously)

Therefore I suggest you get an electrician in to do the job for you. How ever if you feel up to it, you could offer to dig the trench to put the cable in (You can't clip it to a fence) and while you are at it, you may as well lay 2 conduits, 1 for the mains cable, and the other for a phone cable, cat 5 cable. (Computer)
You only want to do the job once, do it right and safe in the first place.

Unless one of the inverter fridge/freezers then you need to consider it at 10 amp when working out volt drop, and volt drop is important with a fridge/freezer, what you say you want does not seem to exceed 13A, if 13A or under simple FCU will do the job, one in house with 13A fuse and a switched one in shed with 3A fuse for lights.

Once over 13A then another ball park.

So 13A you are right on the edge using 2.5 SWA cable it would be good for 53 meters, power not lights, I would be looking at 6 mm SWA as it is common size so not too expensive and it would allow more power latter if required.

6mm is slightly too small for 32A volt drop wise but with a 32A supply it is unlikely you would use full 32A so close enough. For lights 6mm would need a 20 amp supply, however although 3% volt drop is limit for lights, with LED they would still work with the 5% allowed for power.

So I would likely use 6mm cable with 20A MCB in house consumer unit which would allow for electric heating, and within the 5% volt drop for lighting.

However you need to inspect and test and sign paper work to say you have designed, installed and inspected and tested, so you need to work out volt drop and likely earth loop impedance not me, personally I would use three core and use a copper earth, but your designing so you need to work it out not me.

Moasif
A 10 mm2 Armoured cable would be best for starters