Most have a mixture of 12 vdc and 230 vac with a battery and a float charger between the two. Water pump likely 12 vdc but tea urn likely 230 vac lights and fridge could be either.
721.521.2 The wiring systems shall be installed using one or more of the following: (i) Insulated single-core cables. with flexible class 5 conductors, in non-metallic conduit (ii) Insulated single-core cables, with stranded class 2 conductors (minimum of 7 strands), in non-metallic conduit (iii) Sheathed flexible cables. All cables shall, as a minimum, meet the requirements of BS EN 60332-1-2. Non-metallic conduits shall comply with BS EN 61386-21. Cable management systems shall comply with BS EN 61386.
In other words flex is used. There are a whole series of notices and regulations as to what the local council will require I don't know. Even things not down on regulations may be required like fixing boiler double sinks and hot water for washing and I have not a clue as to which ones are recommended and which must be done.
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