Jonathan wrote:
We're planning the ring for builtin appliances in a new kitchen, and
would welcome advice on placing the sockets. Firstly, the sockets must
be hidden, and so below worktop height. In general we estimate about
50mm clearance between wall and back of appliance. A plug is about
30mm depth, and so a flush socket might just do, but could be tight.
Recessing the sockets into the wall would give more clearance, but
this would be more awkward to do. Once the floor is tiled, there will
be about 120mm clearance between bottom of floor units and floor, and
so we were considering mounting surface sockets under cupboards
adjacent to the applicances. However, having the ring be out of the
wall, and either the ring or a spur entering the wall to feed surface
sockets didn't seem that neat. So, no option seem that great, and
advice on where sockets are usually placed for builtin appliances
would be most welcome, and also about the idea (and "legality") of
sockets under cupboards.

Legally you do need to be able to isolate the appliance so fitting
sockets completely inaccessibly behind a built-in appliance is a no-no.

I put my (flush) sockets behind cupboards adjacent to the appliance, and
cut a hole in the back panel of the cupboard in front of where the
socket was, just big enough to get a hand through, switch off the
socket, and to be able to pull the plug back through in order to change
the fuse if need be. If you plan the position of the hole/socket
carefully, the hole will be well above the base of the cupboard or any
shelf therein, so stuff won't fall through the hole and down the back
into oblivion.

David