in electrical junction box is a container for electrical connections, usually intended to conceal them from sight and deter tampering. A small metal or plastic 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, under floors or concealed behind an access panel - particularly in domestic or commercial buildings. An appropriate type (such as that shown on the right) 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.