Earthing (or grounding) is an essential part of any electrical installation. Within industrial and pharmaceutical plants with potentially explosive atmospheres earthing plays an essential role in maintaining the electrical and instrumentation systems in safe condition. The earthing system, although a single physical system, it carries out many different functions including automatic detection and clearance of electrical faults, prevention of dangerous potential differences which could cause injury, prevention and dissipation of static charges, screening and reduction of interference in instrumentation system and provision of a reference point for intrinsically safe Zener barriers systems