Junction Box

Junction Box An electrical junction box is a container for electrical connections, usually intended to conceal them from sight and meter tampering. A small metal or plastic junction box may form part of an electrical conduit wiring system in a building, or may be buried in the plaster of a wall, concealed behind an access panel or cast into concrete with only the lid showing. It sometimes includes terminals for joining wires. A similar container used for joining wires to electrical switches or sockets is called a pattress. The term may also be used for a larger item such as a piece of street furniture. In the UK, this is sometimes called a cabinet. See Enclosure (electrical). Junction boxes form an integral part of a circuit protection system where circuit integrity has to be provided, as for emergency lighting or emergency power lines, or the wiring between a nuclear reactor and a control room. In such an installation, the fireproofing around the incoming or outgoing cables must also be extended to cover the junction box to prevent short circuits inside the box during an accidental fire.

How Does a Junction Box Work?

  1. Junction Box

    • A junction box is a box (either plastic or metal) used by electricians to join wires together. They can be located in walls or ceilings and are usually covered by a cover plate.


    • Knock-outs are circular pieces on the sides of each junction box. When you take out the circular piece of plastic or metal, you can put a connector on that holds the wire or conduit to the junction box.


    • Junction boxes come in many different styles. You can purchase ones that have a deeper box (allowing more wires to be in the box) or smaller ones that accommodate only a few wires. You can also attach them to 2 x 4's, beams in ceilings or even to the drywall.

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20th Jan 2015

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