Best type of conduit to use?

if you are doing this in T and E, then mini-trunking or indeed almost anything will be OK (including clipped direct, but it looks awful..

For the odd times I do, I tend to do outdoor sockets on a switch and  fused spur, so that when folk go on holiday or it gets damaged by the kids bikes, there is an obvious place to turn it off, but that is not strictly needed for the regs. Also it means you can cover the drill hole with the box..

Remember to drill slightly down hill so water drains to the outside, rather than inwards,and make sure condensation has an escape hole on the underside

A double pole isolator in the form of a switched fused connection unit is good, or a removable 13 Amp plug, as long as it can be kept out of the rain. Total double pole disconnection is essential when the pond pump gets filled with water and becomes faulty due to old age, thus tripping off the supply circuit and perhaps others of a split load consumer unit. They all always do get filled with water and become faulty......eventually.


Z.

To clarify, I was suggesting the outdoor socket(s)  and the fused spur that feeds it on opposite sides of the wall, so the FCU is indoors in the living room or conservatory or whatever, while  the socket it isolates is the  brick wall thicknesses behind it on the outside . Labelling the indoor switch  'outdoor power' helps prevent random call backs about it not working from less technical users.

The other advantage of an FCU is if an outside flood light is needed too, it can all be fed by the same 13A branch