How to Install an Electrical Junction Box

An electrical junction box .
  • 2 hours
  • Intermediate
  • 20
What You'll Need
Needle Nose Pliers
Electrical Junction Box
Wire Nuts

An electrical junction box is a safety box used to cover wires that have been joined in a single electrical unit. An electrical junction box can either be made of metal or plastic. To save on costs, plastic junction boxes offer a cheaper alternative to metal. Since most electrical codes today require that wire splices should never be placed outside of a protective covering, these boxes are required to be installed when joining electrical wires. To install an electrical junction box, read on for further instructions.

Step 1 - Plan and Prepare

Before installing the junction box, determine the best location where it can be mounted. The box can be mounted anywhere inside the room — on the ceiling or on the walls. When the location has been set, run the wires to meet in that location. Use a drill in case the wires need to run through walls.

Step 2 - Shut Down the Power Supply

Before working on the wire splicing and installation of the junction box, make sure to turn off the circuit breaker inside the main panel, to prevent accidents. Afterward, double-check the current using a voltmeter or multimeter. Safety should always be a priority when working with electrical projects, so make sure that there is no current running through the wires.

Step 3 - Mount the Box

Before proceeding to connect the two sets of wires together, mount the box onto the planned location first. Make sure that the screws are set tight to hold the box firmly.

Step 4 - Insert the Wires

An electrical junction box.

Take off the cover plate of the electrical junction box first. Then open or remove the two knockouts on the box to insert both sets of wires inside the box using cable clamps to secure them. Slide the wires inside the box until a sufficient length is inserted.

Step 5 - Connect the Wires

Follow the color codes on the wires completely. All of the black or hot wires should be connected together. White or neutral wires should be connected to other neutral wires as well. Connect the green or bare wire to the other green or bare wire to complete the connection. To make the connection, twist the wires together using pliers. Make sure to use wire nuts to cover the connection between wires. Color-coded wire nuts determine what sizes and how many wires can fit inside each specific wire nut. Wire nuts can also be used to secure the bare ground wire connections.

Step 6 - Install the Cover

To complete the installation, put the cover back on the junction box to hide the connections. It is important to tuck the wires in completely in order to allow the cover plate to be installed back with ease. Install the necessary screws to hold the cover plate. Turn the electrical power back on and check if the connection is successful.