Bus duct, or busway, is a prefabricated electrical distribution system. In other words, it is a system that distributes electrical power throughout a building. The two types of these systems are feeder and plug-in. A feeder busway distributes power to one area, whereas a plug-in busway is used to distribute power over a larger area. The busway ducting includes several components.
Insulated metal bus bars, usually made of copper or aluminum, are inside the ducting. They are the main components of a busway system because they conduct electricity along the busway and are the "backbone" of the whole structure. Although they are called bars, some are actually tubular in form. Some bars are wafer thin, but the ones used in substations are sometimes metal tubes of 50mm thickness, or about 2 inches.
Quite often, a busway begins with a tap box, of which there are several types. A tap box feeds power to the busway and is connected via wire and pipe to a distribution panel. An end cable tap box is the most common kind of tap box. It plugs into one end of the busway run, and a neck that protrudes from it encloses lugs needed to deliver power to the bus bars. You can remove the sides of the housing to gain access to the lugs if necessary. A plug-in tap box plugs into a plug-in busway via a port hole. A big advantage is that it can plug in at any point along a bus run. A center tap box is designed to supply power to the middle section of a busway run.
All dead ends on a busway need to be closed. This is accomplished with an end closure or end cap. An end cable tap box needs one end cap. A plug-in or center-tap box needs two end caps. Additional bus duct components include elbows, transition pieces, short pieces, fittings, devices and accessories. The components on which you can suspend a busway, of which an almost unlimited selection exists, include bracket supports, strap hangers, rod hangers and messenger cable suspensions.