Installation of an Electrical Box

Electrical boxes are required for safe power delivery and use.

Electrical boxes come in various shapes (round, square, rectangular), sizes, and can be made of metal or plastic. Some are designed for outdoor use. Some are used as attachment points for light fixtures, outlets, switches or simply as junction points for multiple wiring circuits. Some are designed for installation into exposed walls or ceilings ("new work" boxes) and others are designed for placement in finished surfaces ("old work" boxes). Common to all is that they serve the function of securing the ends of electric cables and protecting (and shielding) the wire connections. Almost all wiring projects require at least one electrical box.

Things You'll Need

• Drywall screws or common nails.
• Hammer
• Flat head screwdriver.
• Phillips head screwdriver.
• Drywall Saw
• Utility knife

Instructions

1. Decide whether work will take place at an exposed wall or ceiling or if the original surface must remain. Exposed walls require "new work" boxes. Metal boxes are nailed or screwed to a home's framework so that the open face of the box extends past the face of the frame the thickness of what will be the wall covering. Plastic boxes may have fasteners (usually nails) pre-mounted in the box. Simply position the box and drive nails with a hammer. Many new work boxes, metal or plastic, will have built-in guides that will allow for the thickness of a typical wall covering such as gypsum board.

2. Finished walls that will remain intact require old work boxes. These are installed by cutting a hole the size and shape of the box in the wall or ceiling (making sure the hole is in between frames) with a drywall saw or utility knife. Old work boxes usually have "ears" on opposite sides which are designed to secure the box to the finished wall itself. Old work boxes are not attached to the frame of the house. The box is pushed into the hole (a flange along the edge will keep it from falling in) until it is flush with the wall. Some boxes are designed for the "ears" to spring back and secure the box from coming back out. Others require one or two screws to be tightened.

3. Metal boxes may have built-in cable clamps which will require a screwdriver to tighten and secure the cable. Others may have a knock-out hole that will require a separate cable clamp. Knock out the piece of metal covering the hole with a hammer and flat head screwdriver, then place the disassembled clamp in the hole from the outside of the box with the threaded end facing in. Screw on the nut that came with the clamp and tighten it by hitting one of the bumps on the nut with a hammer and flat head screwdriver. Clamps are designed for armored or non-metallic cables and are not interchangeable. Plastic boxes usually have "push in" clamps which are designed only for non-metallic sheathed cables.

Tips & Warnings

• Always make sure that clamps and cables are secured to the old work box before the box is installed.

• Always make certain that electrical power is off when doing electrical work.

References

• "Ortho's All About Wiring Basics"; James D. Blume, Editor; 2000