At extra high voltages (more than 300 kV) in outdoor buses, corona discharge around the connections becomes a source of radio-frequency interference and power loss, so special connection fittings designed for those voltages are used.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.