1 of 2
Photo 1: Fill with setting-type compound
Bevel the edge of the drywall with a utility knife. Then fill in the
gap with fast-setting joint compound.
2 of 2
Photo 2: Mud and tape
Spread the fast-setting compound into the gap and surrounding
area and embed the tape right up to the edge of the electrical box.
Let it set up and apply the final two coats of lightweight compound.
Sand with a medium-grit sanding sponge.
We've all done it—cut the electrical box opening too large.
Sure, you can cover it with a “jumbo” electrical plate, but
that can look pretty stupid, especially if there are other
boxes nearby. Instead of squishing joint compound into the
gap (it'll always crack), try this fix.
First prepare the gap and fill it with compound (Photo 1). Then apply joint tape and additional mud coats (Photo 2).