Assessment of Soil Resistivity on Grounding of Electrical Systems: A Case Study of North-East Zone, Nigeria

Electricity is dangerous and required proper grounding to prevent unwanted voltage from passing through personnel, critical equipment and other nearby metallic objects. This paper presents the impact of soil resistivity on earth electrode grounding by carrying out extensive measurement of tower footing earth electrode resistance and soil resistivity along the 330kV transmission line between Jos and Gombe in the North-East zone of Nigeria, using the Fall-of-Potential method and Wenner Array method. The study revealed that the values of earth electrode resistance range from 0.3 to 20 Ohms while the soil resistivity ranges from 60 to 1000 Ohm-m. The results confirmed that the values of earth electrode resistance have great impact on the types of soil in which the earth mat was grounded; hence effort should be made to improve soil resistivity for effective grounding of systems.