Geo-electric Ground Earthing Investigation in Basement Complex Environment

Abstract

The ground earthing investigation was carried out in the vicinity electrical transformer within the Iyana-emirin community, Ado Ekiti to understand the causes of incessant facility damage due to thunder strike and eventual explosion. Profiling measurement using the dipole-dipole electrode configuration was employed for three traverses around the facility while eight points along these traverses were sounded. The sounding data identified four lithologic layers (lateritic topsoil, clay, sandy clay, weathered layer, and basement) in the study area. 2D resistivity images were generated along four traverses with respect to depth. Results from the VES and 2D resistivity image indicated that the layer within the earthing medium is resistive. The study reveals that the facility damage experienced in the area is due to the high resistivity values across the study area getting above the recommended earthing standard (2 - 5 ꭥm)/(5 – 25 ꭥm) for substation installation. There is a need to carry out artificial enhancement by introducing conductive materials (like lime, salt, charcoal, and ashes) into the subsurface to reduce the resistivity thereby making it suitable for the intended purpose. Also, the identified low resistivity portion could be targeted for burying earthing/grounding material and further enhanced for better performance.