Mounting a double outdoor socket on an uneven lumpy stone wall question

[Lexicon]

What is the preferred trade method of doing this avoiding chasing out a flat surface ?
The socket housing has a flat rear rubber gasket surface.

 

[roys]

Knock off the worse of the wall lumps, I then pack out any gap where the screws are with tap washers as you can buy them in packs of 50 they are about 5mm thick with a 3 or 4mm hole in it and made from quite a hard rubber. I also seal up the cable where it enters the rear of the socket, and around the side and top edges against the wall. Also drill a 3 mm ish drain hole in bottom of box.

 

[SPECIAL LOCATION]

With almost every outdoor accessory I fit I tend to use one or more tap washers between the accessory and the wall..

As too often plastic back-boxes can start to twist when you are securing it up tight, and the tap washers have some flexibility so you can compensate for any uneven bits on the wall!

Which reminds me I need to pick up another bag..
e.g. https://www.amazon.co.uk/Rubber-Washers-Plumbing-External-Diameter/dp/B07FVV551C/ref=sr_1_8
Other suppliers and/or brands are available!

Sometimes its useful to have both the large and the smaller diameter washers.
Try your local plumbers merchants, see if they do bags of traditional flat washers for hand basin (small) and bath taps (large).

 

[roys]

Snap

 

[binky]

you can survive without the rubber gasket, use a TRS gland for the cable entry, or silicone the hole. NB dont bring the cable in through the top of the back box, unless you want it to fill up with water. Also do drill a small drain hole in the bottom.

 

[Nicky Tesla]

A good dollop of putty and a couple of screws and packers.

 

[Lexicon]

TRS gland and tap washers seem to be the way to go