Effective Grounding Schemes in High Resistivity Soils for Mission Critical Facilities: A Case Study

Grounding systems with low earth resistance values are inevitable for the reliable functioning of critical instrumentation centres. In certain soils, the resistivity undergoes very large seasonal variations. Conventional earthing practices will not provide desired results in such cases. In such soil conditions, devising an optimal grounding system that offers acceptable level of earth resistance through out the year poses serious design challenges. This paper presents a solution to such cases. The approach is to derive a ‘multiple electrode, non-homogeneous soil solutions’. Two case studies successfully employing such grounding schemes are also discussed in the paper. This grounding arrangement can be well adopted in high resistivity soil conditions where low earth resistance values are pre-requisites for critical functional purposes.