Electrical switches and outlets that move around because the box is too recessed can be a safety problem. Outlet shims offer a quick and inexpensive solution.
By the DIY experts of The Family Handyman Magazine:May 2009
Outlet shims solve the problem created when electrical boxes are recessed too deeply; use them as needed for new installations and for repairs to old, wobbly outlets.
Turn off the power and check with a voltage tester to make sure there's no power to the outlet. Unscrew the outlet and add enough shims to bring the outlet flush to the wall.
Screw the outlet to the box and reinstall the cover plate. Turn the power back on.
The constant movement of loose electrical outlets can loosen the wires connected to the outlet and create dangerous arcing. Luckily, the fix is simple. If the outlet is recessed less than 1/4 in. in noncombustible material, you can fur it out with outlet shims as shown. If it's recessed more than 1/4 in., use a plastic extension ring. You'll find both in the electrical department at home centers.
Turn power off before doing this repair.
Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.
Avoid last-minute shopping trips by having all your materials ready ahead of time. Here's a list.