An electrical conduit is a global term to describe any closed pipe, channel, or duct used to route or protect electrical wiring. Conduits may be round, square, or oval in cross section and may be of one piece construction or feature removable covers or lids. Commonly used conduit construction materials include mild steel, aluminum, and PVC plastic and each featuring its own specific methods of joining individual sections. Electrical conduit may be surface mounted on walls and ceiling joists or may be buried under ground or embedded into walls. Most conduit systems also feature selections of auxiliary fittings such as inspection boxes, bends, and junctions which aid in their installation and maintenance.
Electrical wiring is fairly sensitive and prone to impact and rodent damage, moisture ingress, and weathering. An electrical conduit system protects wiring and makes complex routing neater. These systems consist of closed pipes, trunking, or ducts which prevent wiring from getting wet, being kinked, crushed or cut by passing traffic, eaten by rodents, or degraded by ultraviolet exposure. Most conduit systems consist of round section pipes, although square ducting is also fairly common, particularly where large volumes of wiring are involved. Square ducting is typically open on one side with a removable lid which makes access to the wiring easier.
Although most modern electrical conduit is made of mild steel, aluminum or PVC plastic, many older systems still feature pipes made from pitch impregnated cellulose fiber and fired clay. Perhaps the best example of these is the bitumenized Orangeburg conduit still very much in evidence in many older homes. These old pipes are generally oval in cross section with adhesive and gasket free joints. Although serviceable, these conduit types are generally less durable than modern systems and often fail due to brittleness and compression damage. Fired clay conduit is also a dated system; this variant is not as common as Orangeburg pipe but also very brittle and prone to impact damage.
Most electrical conduit systems have large selections of associated fittings which make installation and maintenance a relative breeze. These include a variety of bends, inspection boxes, junction boxes, joints, light fittings, and socket outlets. Many conduit types including steel and PVC pipes may also be bent on site to accommodate any routing or obstacle clearance requirements. Conduit runs may be mounted on the surface of walls, across ceiling joists, or within the wall cavity. In some cases, the conduit can also be buried underground or embedded in chased grooves in brick walls which are typically plastered over once the conduit is secure.