The mounting bracket for my new wall light fixture is incompatible with the existing electrical box. While it seems reasonable to drill the mounting plate so that the top/bottom mounting screws can be used, the horizontal mounting pins for the fixture extend beyond the cavity of the electrical box onto the plaster wall.
Is it safe to simply remove the plaster behind the pins so that the plate will lay flat against the wall? Is it safe that the grounding screw will be outside of the box on top of the plaster wall?
I'm handy, but I know very little about electrical work.