This shed is being supplied by a 50mm 5core SWA. This is to supply it at 100 Amp 3 Phase with minimal voltage drop, as the building further downstream will be an office with sensitive electronics inside.
This building will have a Hager JK12SPD board which is a 3 phase board (380V which used to be 415V before regs changes) and domestic properties have a single phase supply (230v which used to be 240V before regs changes )
We have stone buildings here but the majority are plastered on the inside so we use cable channeling to cover cables and protect them from the mortar mix. Most outlets on a property like this will have flush outlets and switches
I have had bare granite barn conversions which were wired in galvanised trunking with galvanised conduit drops, with surface services like outlets and switches
Running cables can be a nightmare in some old buildings as they tend to be very fragile which often causes damage to floors and ceilings just by disturbing them. Old ceilings over here are made up of lime plaster with horsehair in it and that is plastered over thin slots of wood we call laths