Soil Resistivity Adequacy Assessments: Case Study of Proposed School of Environmental Technology Building Federal University of Technology, Akure

Abstract

Earthing system are used to divert faulty currents to the ground or earth. Thus, a properly designed earthing system capable of dissipating fault currents safely to the ground or earth is required for safety of life and property hence the focus of this project in determining earthing resistance/resistivity adequacy of a Proposed School of Environmental Technology Building (PHASE III), Federal University of Technology, Akure, Nigeria. 4-point measuring technique, Wernner method, using digital earth tester, model 6472-AEMC is used in this work. The site is divided into five transverse for the tree buildings on site. The result shows that the earthing resistance of one building (transverses 1 and 3) generally varies from 3.9? to 54 ?, second building: 2.3? to 11.9? and for third building: 2.2? to 6.4 ?. Of the samples taken, building 1, 2 and 3 conformed to 4%, 47% and 50% of International Electrochemical Standard (IEC) and 48%, 60% and 100% of British International Standard (BIS). Transverse 5 is the best transverse for earthing because 50% of the points met IEC and 100% of the points met BIS standard for earthing resistance value. Earthing rod or mat can be installed at some points in building 1 and 2 in their transverse but not at every point but at any point in building 3 transverse. Earthing rod or mat at can be installed at 150mm (minimum) in the transverse that meet up the international code’s resistance value requirement.

The result also establishes that resistance is directly proportional to soil resistivity, the lower the earth resistance the lower the soil resistivity. Building 3 which is closest to swamp area has lower resistance value (2.2?). The site is okay for earthing without any earthing improvement. Earthing resistance value test should be carried out on site prior earthing installation.