Earthing (security establishing) busbars are commonly uncovered and catapulted straightforwardly onto any metal undercarriage of their hole. A busbar is usually a conductor or an assembly of conductors for collecting electric currents and categorizing them into outgoing feeders. The material synthesis and cross-sectional size of the busbar decide the greatest measure of current that can be securely conveyed. Busbars can have a cross-sectional area of just 10 square millimeters (0.016 sq in), yet electrical substations may utilize metal cylinders 50 millimeters (2.0 in) in width (2,000 square millimeters (3.1 sq in)) or more as busbars. An aluminum smelter will have extremely huge busbars used to convey a huge number of amperes to the electrochemical cells that produce aluminum from liquid salts.