Installing Electrical Boxes

MATERIALS: Remodeling (old-work) box, screws

TOOLS: Electronic stud finder, utility knife, drywall saw, saber saw or rotary cutter, screwdriver, drill

Floor-level receptacles are usually 12 to 15 inches off the floor. Rather than pulling out their measuring tape, electricians often set their hammer head down on the floor and use the length of the hammer to position the center of floor-level receptacles in the wall.

Installing electrical boxes is easy in new construction because the walls I aren’t in the way. You have more I variables when working with existing walls. Self-attaching remodeling boxes make the job easier. All you have to do is cut a hole, run the cable, clamp the cable to the box, and install it in the wall.

Use a stud finder to make sure you won’t hit a stud, joist, wiring, or anything else hiding in the wall. Lay out the hole by tracing around the box, or ask the store for the layout template. (The templates are shipped with the electrical boxes but usually get separated from them by the time they reach the store shelf.) Cut the hole carefully. The box should fit into the hole snugly, but not so tightly that you have to force it. If the hole is too wide, the box may not effectively attach to the drywall or plaster.

IN NEW CONSTRUCTION ATTACH ALL THE BOXES TO THE STUDS BEFORE RUNNING CABLE. Receptacle boxes are usually placed 12 inches above the floor, and switch boxes 45 inches above the floor. Hold a nail-on box with its front edge positioned out from the stud the thickness of the drywall, and nail it in place.

Installing remodeling boxes

1 CUTTING A HOLE IN DRYWALL. Use a pencil to mark the location of the hole (check for studs) and score the paper surface with a utility knife. Cut along the inside of the knife-cut with a drywall saw. The resulting hole will be free of ragged edges. You also can cut drywall with a spiral cutting tool or a saber saw.

2 CUTTING A HOLE IN PLASTER WITH A SPIRAL CUTTING TOOL. Because of the motor's high RPMs, this tool won't rattle lath or loosen plaster Set the base on the wall and tip the blade away from the surface while you let it come to full speed. Then tilt the blade gently into the wall. Have extra blades on hand; they dull quickly on plaster.

3 CUTTING A HOLE IN PLASTER WITH A SABER SAW. Cutting through a lath and plaster wall is difficult and often results in cracked plaster. Drill holes at each corner and score the face of the plaster with a utility knife. Cut with a saber saw equipped with a fine-tooth blade. Press hard against the wall to reduce lath vibration.

INSTALLING A BOX WITH SPRING FLANGES. If you buy this kind of box, make sure both flanges spring out firmly from the box. Push the box into the hole until the flanges are free to spring outward. As you tighten the center screw, the flanges should move toward you until they fit snugly against the back of the drywall or plaster.

INSTALLING A BOX WITH SIDE CLAMPS. After pushing the box into the hole, tighten the screw on each side. Each clamp extends behind the wall to hold the box in place.

USING MOUNTING BRACKETS. Push a metal box with plaster ears into the hole. Slip a bracket in on each side, pushing it behind the wall's surface. Pull the bracket toward you until it's tight, push the box tightly against the wall, then fold the tabs into the box with your thumbs. Tighten the tabs with pliers.

INSTALLING A BOX WITH FOLD-OUT EARS. These plastic remodeling boxes have ears that swing out behind the drywall or plaster. Push the box into the hole, then turn the screws clockwise until the ears clamp onto the back of the drywall or plaster. Switch boxes are also available with this same wall-grabbing mechanism.


1 ADJUST THE PLASTER EARS. Many metal boxes have adjustable ears. Cut the hole and chip out the plaster above and below so the ears will fit. Loosen the two screws and adjust each ear so the face of the box becomes flush with the wall surface. Tighten the screws.

2 ANCHOR THE BOX TO THE LATH. Lath cracks easily, so work carefully. Drill pilot holes, and drive short screws to anchor the ears to the lath. Expect to do some wall patching after using this method.

Installing ceiling boxes

MATERIALS: Ceiling box, brace, 1 1/4-inch wood screws

TOOLS: Drywall saw, hammer, drill, screwdriver, reciprocating saw or metal-cutting keyhole saw, adjustable wrench

1 When framing is accessible, attach a ceiling box to a joist. Install this type of box in unfinished ceilings or ceilings with a large hole. Drill pilot holes and drive in 1 1/4-inch wood screws to attach it to joist.

2 Install a braced box from above. Buy a new-work box with a brace. Slide the box along the brace to position it. Tighten the clamp. Attach the brace to the joist by driving in 1 1/4-inch wood screws.

It’s essential that the new ceiling box can carry t\ weight of the fixture you are planning to hang. Talk a sales associate to make sure you’re buying the right box and installing it properly.

1 SLIP IN THE BRACE. Assemble the box on the brace to understand how it goes together, then take it apart. Push the brace in through the hole and spread it apart until it touches the joists on both sides. The legs of the brace at each end should rest on top of the drywall or plaster.

2 TIGHTEN THE BRACE. Measure to make sure that the brace is centered in the hole. Position it on the joists at the correct height so that the box will be flush with the surface of the ceiling. Use an adjustable wrench or channel-type pliers to tighten the brace only until it is firm. Tightening beyond this point can cause the ceiling to crack.

3 ATTACH THE BOX. Attach the U-bolt assembly to the brace so that the assembly is centered in the hole and the bolts face down. Thread cable through the cable connector and into the fan-rated box. Slip the box up so the bolts slide through it and tighten the nuts to secure the box.

Log in to comment