Installing electric box

Metallic boxes can be used with either nonmetallic Type NM-B or metallic sheathed electrical cable. Nonmetallic plastic boxes are designed for use only with nonmetallic sheathed electrical cable. Whatever the material, electrical boxes can be loosely divided into two types:. Installing an old work box into an existing wall to add an outlet or wall switch is an easy project that requires just a few common tools that you may already own if you're familiar with basic electrical repairs.

The most difficult part of the project is running cable through the walls ; this process can take several hours, even though the box itself can likely be installed in a matter of minutes.

Before getting started, it helps to understand the purpose and anatomy of an old work electrical box. An old work box is designed to be installed after the fact—on walls that are already finished. They are often used in situations where you are adding outlets or extending an existing circuit in a room that is already finished.

Because these situations don't allow you the opportunity to attach the box directly to studs, these boxes need a different means of anchoring. To anchor them in place, these boxes have a clever fastening system that uses retention tabs and mounting ears located in opposite corners of the box.

Once the box is inserted into the wall cutout and the screws are tightened, the rear retention tabs open up and draw up tight against the back of the drywall or plaster while mounting ears on the front of the box press against the front face of the wall. The front ears and back retention tabs essentially "pinch" the box tightly in place against the wall surface. If you will be running live electrical wire to the new electrical box, it is absolutely essential that you turn off the circuit breaker that controls the circuit before you pull and attach the cable.

If you don't know which breaker to throw, you'll want to turn off the main breaker , which will cut power to the entire house. The screw that goes into the retention tab on the box may sometimes be very tight when the box comes from the manufacturer.

This would require you to put considerable pressure against the wall when you turn the screw, which may damage the wall. This effectively precuts the threads in the plastic retention tab, making the screw easier to turn later when you are securing the box in the wall. After the screw is drawn up slightly, back the screw out to allow the retention tab to go back into its original folded position. Old work electrical boxes made from PVC use an integrated quick-clamping system to hold the nonmetallic NM-B cable to the box.

These clamping tabs can be a little difficult to open up. This will loosen the clamp and make it easier to insert the cable. Next, you'll need to create the wall cutout. Position the electrical box backward against the wall, in the exact position you plan to install it.

Take a pencil and trace the outline of the box on the wall, avoiding the box's "ears. Make several passes with a sharp knife. Drill starter holes at each corner and then cut with a jigsaw. Press the saw firmly against the wall to minimize lath vibration. Alternatively use a rotary cutter equipped with a plaster-cutting bit. Practice first because it is hard to control. The round plastic ceiling box left has "wings" that rotate out and behind the wall surface.

One metal box center has a flange that springs outward when the box is inserted; tightening a screw brings the flange forward.

A variation on this has side clamps that move out and toward the front as screws are tightened. Yet another type right uses separate mounting brackets that slide in after the box is inserted and bend over the sides of the box to lock it in place.

Attach lightweight fixtures onto drywall or plaster without wall studs. Follow these expert tips to easily install an electrical box.

Each product we feature has been independently selected and reviewed by our editorial team. If you make a purchase using the links included, we may earn commission. Save Pin FB More. Bedroom with bedside lamps and wooden nightstands. Credit: Edmund Barr. Follow our step-by-step instructions for installing an electrical box in drywall. Stud finder Torpedo level Utility knife Screwdriver Hammer Drill Drywall saw or rotary cutter or jigsaw Remodel boxes acceptable under local code Cable clamps, if needed.

Seckinger, George D. Patent 2,,, issued March 3, These box mounting strips permit mounting an electrical box in a wall without having to secure the box to a wall stud. These clips may be used with standard steel electrical boxes that include plaster ears. Illustration, adapted from Caddy's Old Work Box installation sheet cited below.

Hire a licensed electrician. Take a look at this metal box with BX wiring shown above: you will need a bit of a notch to re-insert this box into the wall cutout in an "old work box" installation. An alternative to old work electrical box clips is to use the newer plastic swing-arm or swing-ear "old-work" electrical boxes like the round electrical "box" shown below.

Watch out : do not use a swing-arm electrical box mount nor any other old-work electrical box mounting system to support ceiling light fixtures or fans whose weight may exceed the box mount system rating and cause the fixture to fall from the ceiling. These U. In the U. Contributions to this list are invited from all readers. Above: the "Madison Bar" or electrical box support designed and patented by Albrecht and filed by Madison Equipment Co. Try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.

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