This is the inside of a large garden shed. OK garden is 20 acres of woodland the house is not lived in except for when visitors come this guy lives in the shed. Well it is around 8 sheds which were combined into one when the poll tax came in and they wanted to charge poll tax on each shed.
There are sheds and there are sheds and the name shed does not really describe some of the structures.
When wiring we do tend to look at if there is any requirement for heating. Clearly in the picture shown he has a log burning stove and 20 acres of woodland to produce the logs. There is a huge covered log stack and wood is laid down for three years before burning so no lack of fuel. However he still uses an electric fire. Wood burners do not light by the flick of a switch and so it is common to use electric while the stove is heating up.
I am sure we all think we will never use an electric fire but any building large enough to have a log burner will likely at some point want electric heat.
I have questioned a few times about the minimum temperature a fridge/freezer will work in. Clearly any freezer will auto defrost needs it warm enough and dry enough for the water to run onto the motor top and evaporate. And since there is no heating in a fridge it can't keep food at 5°C if outside it's less than 5°C. As a result only chest freezers which have no auto defrost are suitable for use when the ambient temperature is less than 10°C. For a shed I would think a fridge would be set at 12°C the standard temperature for beer and wine so the ambient would need to be around 14°C but I use a cool box and it is only ever switched on when eating and/or drinking outside the house and clearly no problem in storing in shed.
To me shed electrics come in two stages.
1) Simple FCU in house if required a RCD FCU which supplies shed to a socket and from the socket to a switched FCU with 3A fuse feeding the lights. It will require notification where I live but not in England.
2) A supply direct from consumer unit to a mini consumer unit in the shed which in turn supplies sockets and lights.
So the big question is if 13A is enough? If so it's the method 1) which is cheap and possible to DIY. If 13A is not good enough then since notifying costs so much it's down to an electrician to do the work.
So method 1) the ring final can likely supply the shed and if you use a metal FCU you can easy gland into the box with SWA cable. Same with shed use metal clad boxes and easy to gland SWA. I would use three core even though you could use the steel as an earth mainly as likely it will never be tested and so your not sure if the earth is good.
