Current for Design of Grounding Systems

A simple method to estimate the current for calculating the size of the grounding conductor and for evaluating the step, touch and transferred potentials, is presented. The factors effective in making these currents different from the total fault current have been indicated. Various types of substations, different fault locations and a wide rangeof parameters of aerial ground wire encountered in practice are considered. Data presented emphasizes the saving in grounding design costs that can be realised by using maximum realistic ground currents rather than maximum calculated total fault currents for evaluation of step & touch potentials.