A conduit box is a metal box that protects electrical or telecommunications connections. The boxes have many different names such as junction boxes, electric cabinets or enclosures. Inside a conduit box, there are wires that connect the local power or communications systems to the main system. These gray or green boxes are common in many low-density population areas; high-density areas typically have underground boxes to create an additional layer of protection. These boxes are also commonplace inside factories, power plants, and other industrial areas as well as some commercial and residential buildings.
The main purpose of a conduit box is to protect the wires inside. These boxes are typically made of sturdy reinforced steel that is insulated against electrical discharges originating from inside or outside the box. They usually have a seal around the access panel that creates a watertight interior. The door often has both an interior and exterior lock to further prevent tampering. In addition to its protective role, a conduit box is also more visually appealing than clumps of spliced wires.
The inside of a conduit box has connections for various local systems and for the main line. Since one of these boxes can carry electricity, phone systems or cable television, the insides vary slightly. In most cases, the main line comes in through the bottom or side of the box and splits to a series of local connectors. The local wires come into the box, usually from the bottom, and connect to their terminals. Using this system, a repair person can selectively turn local systems on and off without interrupting other users.
The most likely place to run across these boxes is on the street, but that isn’t the only way. Many industrial machines require huge amounts of power. Since these systems need access to a larger-than-normal power system, it isn’t uncommon for individual machines to end up wired similarly to a house. This is often done through a conduit box present near the machines. One factory may have several personal junction boxes based on its electrical needs.
Commercial and residential buildings may have internal junction boxes as well. These are most common in buildings with multiple groups of unconnected people, like an apartment or office building. These conduit boxes split the interior systems, giving each subgroup its own access to power and communications. This both helps on billing and provides basic protection from power overloads. The most common locations for a conduit box in this situation are the utility room or basement.