Whenever wires have to be joined together in home circuitry, you need a junction box. In very old homes, you might find capped-off wires behind the walls, but these are a fire hazard and are no longer allowed by the National Electrical Code. In some cases a receptacle or switch box may serve as a junction point, but if neither is available where the wires need to be joined, you have to install a junction box.
- Skill level:
- Moderately Easy
Things you need
- Plastic junction box
- J-box cover
- Utility knife
- Wire splicer
- Twist-on wire connectors
Make sure the power is off before you begin.
Nail the junction box into an available stud or rafter. J-boxes come with preset nails so you can easily to this.
Feed the wires through the self-clamping openings in the back of the box. Feed through enough wire so you have about 8 inches to work with.
Remove about 6 inches of sheathing from both wires by cutting around the circumference with a utility knife, being careful not to cut into the insulation on the wires inside.
Strip about 1/2-inch of insulation from all black and white wires with the splicing tool.
Hold the white wires together so the ends are parallel and twist them together clockwise with pliers. When they are securely joined, screw on a wire cap. Repeat with the black wires.
Twist the ground wires together. You do not need to cap these.
Screw the cover on with the screws provided.
Tips and warnings
- Twist-on wire connectors come in many different sizes. Be sure you are using the correct size for the gauge of wire you are joining.
- Although you can connect more than two wires in a j-box, there is a limit to how many wires the box is supposed to hold. Check your local codes.
- Never cut into wires or splice them until you are sure the power is off. If you are not sure, use a voltage tester.
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