Junction box

Functions of the junction box

A small metal, plastic or fiberglass junction box may form part of an electrical conduit or thermoplastic-sheathed cable (TPS) wiring system in a building. If designed for surface mounting, it is used mostly in ceilings, concrete or concealed behind an access panel—particularly in domestic or commercial buildings. An appropriate type (such as that shown in the gallery) may be buried in the plaster of a wall (although full concealment is no longer allowed by modern codes and standards) or cast into concrete—with only the cover visible.

It sometimes includes built-in terminals for the joining of wires.

A similar, usually wall mounted, container used mainly to accommodate switches, sockets and the associated connecting wiring is called a pattress.

The term junction box may also be used for a larger item, such as a piece of street furniture. In the UK, such items are often 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.

Image:Junction box.jpg|Electrical junction box in the process of installation. Electrical conduits terminate at the sides and cables pass through or are joined inside the box. File:Junction box2.jpg|A metal junction box File:Australian Internal Surface Mounted Junction Box.jpg|Australian Internal Surface Mounted Junction Box—showing wiring stages. File:Kuhlo-dosa med Wago.png|Swedish junction box in Kuhlo-style with lever-connector Wago 221, where ground and neutral are connected in common.

Solar panel

A PV junction box is attached to the back of the solar panel and it is its output interface.

References

Back Junction Boxes

References

1. (25 February 2024). "What is a Junction Box (Electrical Box)?".