A bus duct, as its name suggests, is made up of two main parts: the bus and the duct.

The bus refers to the copper or aluminum busbar that conducts electrical current and is responsible for power transmission.

The duct is a prefabricated electrical enclosure in which the energy‑carrying busbars are installed.

Other names for a bus duct include “busbar trunking” and “busway”, which carry similar meanings.

The term “trunking” refers to a prefabricated electrical channel designed to accommodate conductors, which may include copper cables or copper/aluminum busbars.