How to install an outlet into a masonry wall.
Okay, first we’re gonna take a diamond wheel and a grinder, and maybe a shop vac to control dust, and we’re gonna grind out the shape of the electrical box. Then, we’re gonna cut a pathway down the wall and chisel out the remaining material to allow a nice chase for the wire to run.
Next, we’re gonna drill around the perimeter of the box with a masonry drill to try to remove more of the material. The rest of it can be chiseled out with a masonry chisel.
Next, we’re gonna drill from our pathway for the wire into the box chamber so that our wire can fit nicely in place. Yours might be slightly different, but you get the idea.
Now once everything fits into place, we can seat the box into the wall with some expanding spray foam. Now what I’ve done ahead of time is cut a prop stick for it so that once I spray it, I can prop it in place and let it dry overnight so that it sits nice and tight. In our case, we ran Romex down the wall, but in some local areas you need to use shielded cable like MC wire or something, but you get the idea there too.