I cut a notch, but the 2x4 that holds the shelf perfectly covers the outlet. I just took the box off, flipped the switch upside down, and reattached it to the wall. Of course I busted up the wall a bit, and the one hole doesn't hold it well, but with the case facing down, the notch in the shelf will hold it against the wall.
I'm having major issues with this shelf as far as getting it level, stability, getting it to but up against the wall, getting it secured to the wall without the masonry bolts pulling out, etc. Basically everything. I think I have to walk away from this and come back. I suspect that with no "base" on this unit, everything is moving around a lot more and making everything more difficult in general. To be continued I guess.