Have this outlet on the side of the house, what i'd like to do is change out the box to a 2 gang and then run wire under the deck (3 season room) to the front of the house to another 2 gang box. The wire you see coming down is for 12v lawn scaping lighting, which to be honest i'd like to replace that transformer with something that a little more advanced (changes turn on and turn off time automatically for time of year over just a set on off time like it has now) but that's a project for a different day. I'm assuming I should be using conduit but what kind do I need? What is the appropriate type of boxes to use? I want this to at least be able to pass a house inspector eye since we are selling this house in a few years and don't want any issues. Also, any types on mounting a the box on the stone? I know to use masonry anchors but how do I get a flat box to mount to a not so flat stone foundation?
Go walk onto a residential apartment building in your area, see what those guys are using. Maybe get some free materials while you’re there. For the box you can use standoffs with the tapcons but it will never look pretty
For me it's teck cable (or the American equivalent), the simplest (but maybe not the cheapest or prettiest) way to run power outdoors in hostile conditions.