I need to mount a new metal gang box in my wall (I need to make it a double instead of a single)
the wall is wood paneling, so I can't just cut a bigger hole a putty it, would it be breaking code to cut back half an inch or so of the outside lip of the box so I can fit a drill bit up and in there to screw it to the 2x4 or does putting that small hole in the metal box void it?
I need to use the metal box for grounding reasons.
dang, I can't find the section in the code but basically, when mounting a box in a flammable material (like wood paneling) the box must be flush with the face of the wall. sounds like you need an old work box aka cut in box. Here is one type. Many of them (including this type) is gangable so you can put 2 or more together to make a 2 gang (or larger) box.