Busways, or bus ducts, are long busbars with protective covers. Rather than branching from the main supply at one location, they allow new circuits to branch off anywhere along the busway. A busbar may be either supported on insulators, or wrapped in insulation.OverviewIn , a busbar (also bus bar) is a metallic strip or bar, typically housed inside,, and for local high current power distribution, transmission, or switching s. The busbar's material composition and cross-sectional size determine the maximum current it can safely carry. Busbars can have a cross-sectional area of as little as 10 square millimetres (0.016 sq in), but.