Site measurements [earthing systems]

One of the most important factors influencing the performance of the earthing system is the resistivity of the medium in which the earth electrodes are situated, i.e. the soil. For uniform soil, the electrode system resistance is proportional to the soil resistivity. It is thus important that the soil resistivity is assessed as accurately as possible. The paper discusses soil resistivity measurements and interpretation, including soil resistivity measurement using Wenner array, Schlumberger array, rod resistance measurement, bore hole logging, etc. Earthing system impedance/resistance measurement and interpretation is also discussed including fall of potential measurement, high current injection, earthing system components measurement. Sources of error are briefly discussed