A bonding jumper is a reliable conductor to ensure the required electrical conductivity between metal raceways required to be electrically connected.
Bonding" is a method by which all electrically conductive materials and metallic surfaces of equipment and structures, not normally intended to be energized, are effectively interconnected together via a low impedance conductive means and path in order to avoid any appreciable potential difference between any separate points. The bonded interconnections of any specific electrically conductive materials, metallic surfaces of enclosures, electrical equipment, pipes, tubes or structures via a low impedance path are completely independent and unrelated to any intended contact or connection to Earth. For example, airplanes do not have any connection to the planet Earth when they are airborne. However, it is extremely important for the safety and welfare of passengers, crew and aircraft that all metallic parts and structures of an airplane be effectively bonded together. The laboratories and satellites orbiting in space above the planet Earth obviously have no direct connection with the surface of our planet. All conductive surfaces of these orbiting laboratories and satellites, though, must be effectively bonded together to avoid differences of potential from being induced across their surfaces from the countless charged particles and magnetic waves traveling through space.
The common way to effectively bond different metallic surfaces of enclosures, electrical equipment, pipes, tubes or structures together is with a copper conductor, rated lugs and appropriate bolts, fasteners or screws. Other bonding means between different metallic parts and pieces might employ brackets, clamps, exothermic bonds or welds to make effective connections.
In addition to preventing potential differences that may result in hazards, effectively bonded equipment can also be employed to adequately and safely conduct phase-to-ground fault currents, induced currents, surge currents, lightning currents or transient currents during abnormal conditions.