A busbar, commonly called a bus, is a metallic bar or tube that is used to conduct electricity in generator switchyards, substations, and in high-voltage switchgear and panel boards. Busbars are used when the current is too high for other conductors such as wires or cable. Busbars are produced in a variety of shapes such as flat strips, solid bars, or rods and are made from materials such as copper, brass, or aluminum. 

Important design factors include the ability to dissipate heat, sufficient rigidity to support the busbar’s own weight, and sufficient flexibility to manage movement caused by vibration and thermal expansion. The capacity of a given busbar is determined by the material used and the size of the busbar. Busbars in substations and switchyards are commonly supported by large insulators. They are mounted high enough so that they will not come in contact with individuals or equipment. In other applications they may be covered by insulation. Busbars are connected to other electrical equipment by bolts, clamps, or welding.

A copper busbar in switchgear
Aluminum tube busbar in a generation switchyard