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How to Choose an Electrical Box

Ask This Old House master electrician Heath Eastman explains the uses and purposes of different types of electrical boxes.


1. Heath breaks down electrical boxes into a few categories and explains their differences.

2. Heath starts by explaining that new work boxes are used whenever the walls are being opened up for work. This could be in new construction but also in renovations. They come with brackets on the side to nail directly into a stud from the side.

3. Old work boxes are used whenever the walls are closed up and small additions to the wiring are required.
a. Most of these have tabs that will pop out when pushed into the wall so that they can hold onto the drywall or plaster from the back.
b. They also make some old work boxes that come with angled brackets on the inside of the box that will allow you to screw through the box and into a stud without opening the wall.

4. Plastic boxes are most common and should be used with non-metallic cable wiring.

5. Metal boxes are used when the wiring is sheathed in a metal jacket.

6. Single-gang boxes are intended to hold one electrical device, like a switch or a receptacle.

7. Double-gang boxes are intended to hold two electrical devices.

8. Round electrical boxes are used for lighting fixtures on the wall, like a sconce.

9. Fan-rated electrical boxes are meant to hold ceiling lights with a substantial amount of weight. They do sell other types of boxes for ceiling lights, but Heath recommends always installing fan-rated, metal boxes so that any type of ceiling light can always be safely installed at that location.


Heath described the best style of electrical box for various uses. In general, he recommends plastic boxes for switches and receptacles and metal boxes for light fixtures. Metal boxes are required when the existing wiring in the home is metal clad cable and must be bonded to the ground wire.

All of the boxes Heath demonstrated are available at home centers and electrical supply houses.

Special assistance with this project was provided by Eaton and Eastman Electric.