Currents and potentials along extensive underground conductors

The current and potential along an extensive underground conductor are determined for voltage, current and conductive energisations. The general expressions for current and potential are derived, and it is shown that the approximate relations may be obtained from differential equations based on the equivalent circuit for the underground conductor. In the case of conductive energisation, the point, parallel and perpendicular earth electrodes are considered. it is shown that parallel or perpendicular earth electrodes, being sufficiently short, may be replaced by an equivalent point earth electrode