What Is An Electrical Junction Box?

An electrical junction box is a very important part of your electrical wiring system. Without a junction box, you simply cannot have that many different types of electrical outlets, switches, or data hookups in a room.

Control Box

An electrical junction box.

The electrical junction box is the place where all the wires in a room, or wiring area, are joined together and fed by the main breaker. Junction boxes can then be called a control room of sorts. They send power from the main breaker to the other parts of the room. These junction boxes are usually hidden behind the drywall, or paneling as they serve no aesthetic function.

Metal or Plastic

An electrical junction box can be made of either metal or plastic. They usually measure 2½ inches deep or 3½ inches deep. The larger of the two is able to hold up to five different wires, while the smaller only holds three wires.

Needed for Several Installations

An electrical junction box.

If you are going to be installing several different types of electrical components in a room, then you will need to tie into the existing wiring somewhere. A junction box makes that easier by allowing you to connect directly to the main breaker. This negates the need to running wire through the entire house back to the breaker.