An electrical term that any A&D professional should know. Though it doesn’t have to be rectangular, it’s a container that is used for electrical connections. Whether in the wall, under a raised floor or in the ceiling, they are intended to conceal the connections from sight, deter tampering and comply with codes and regulations for the safety of the building’s inhabitants — i.e., prevent the spread of fire. The term can also be used for electrical connections in cars, as well as audio/visual and cable connections. Some specialty J-boxes are built to withstand explosions or the harsh conditions of marine applications.