Assessment of Soil Resistivity and Earth Electrode Resistance for Power System Grounding in Alimosho, Lagos State, Nigeria

Abstract

Earthing systems safely redirect high currents into the ground. For example, lightning can produce high-magnitude transient currents and voltages with rapid rise times that must be effectively discharged to avoid electrical shocks. Therefore, a well-designed earthing system that can safely disperse large currents is essential for safety. The study is aimed at carrying out a comprehensive interpretation of the soil resistivity of Agbado-Okeodo and AKESAN towns in Alimosho, to estimate the soil resistivity values in order to site substations and transformers within the study area and identify ways to improve soil quality, provide the lowest ground resistivity over an extended time using the current guidelines for grounding electrodes and earthing procedures. Using the Wenner Array method, we measured soil resistivity along a 330 kV transmission line to assess its influence on earth-electrode grounding. The findings showed earth electrode resistance between 4.90 and 22.40 Ohms and soil resistivity from 94.26 to 391.61 Ohm-meters across the two locations. The results indicated a strong link between earth electrode resistance and soil type, highlighting the importance of soil resistivity for more effective grounding systems.