Electrical junction boxes are a vital part of your electrical wiring system. It is a box, made of plastic or metal, which contains electrical connections, and is designed to keep electrical connections out of sight and also to prevent tampering. Electrical junction boxes are part of the wiring systems of domestic, commercial and industrial buildings, although you probably won’t see them most of the time.

Where are they?

In domestic and commercial buildings, electrical junction boxes are often kept out of sight. They form part of the electrical wiring, or conduit, system, that connects lights, plug sockets, fans and heaters to the mains, but you rarely see them.They can be fitted into the plaster of a wall, or cast into concrete so that they are very hard to see, although modern building regulations state that they must be visible to a certain extent. Other types of electrical wiring junction box are designed for surface mounting and are often fitted under floorboards, behind access panels or even in the ceiling. Junction boxes can be made of plastic, steel, fibreglass, bakelite or aluminium. 

What do they do?

The electrical junction box is the container for the wires in a wiring area. The wires are joined together and fed by the main breaker, then the junction box sends power from the main breaker through the wires inside it. In this way, it removes the need to run a wire to the main breaker for every electrical component in the room – such as lights, plug sockets and so forth. Instead, each room or wiring area has a junction box and that connects to the main breaker.

Therefore, the junction box acts as a kind of control centre for the room or wiring area. Different kinds and sizes of electrical junction box. can be fitted, depending on the size and number of wires it will contain, and the kind of electrical components it will be powering.

Junction boxes are also part of the safety system, and they are used where circuit integrity has to be maintained. Emergency lighting systems, emergency power lines and power for other emergency systems such as alarms or sprinklers need to be protected from tampering and also from any accidental damage. These junction boxes are fireproofed and sturdy, to prevent short circuits within the junction box in case of a fire.

Other junction boxes are waterproof – bathrooms, for example, must have electricity, so junction boxes for use outside or in areas where there will be water need to be waterproofed securely.

Although you don’t see them, junction boxes form a very important part of the electrical wiring systems in our homes, schools, hospitals, factories and offices. They allow different kinds of electrical components to be safely and effectively connected to the main breaker, without the disruption of running wire through the whole building for every component. They contribute to the systems that keep us safe at all times and they prevent electrical accidents from occurring.