"Earthing" is connecting the power system or electrical devices or building facilities to the earth. Earthing and bonding are an integral part of any modern electrical protection system design. An effective, low impedance earthing system is a key element of this system. It is crucial to help provide personnel safety, as well as reliable protection for vital equipments and to minimize the interruptions of service and costly downtime. It is a fundamental fact that electricity always flows to the point of lowest potential. The task is to help ensure that electricity, including faults, lightning and electronic noise flows to this point with maximum safety to people, while maintaining the reliability of equipment. Therefore we must help ensure the safe, controlled flow of electricity with minimum voltage drop to earth in all cases. Reliable protection of personnel and structures demands a systematic and comprehensive approach to minimize threats caused by transients and other system disturbances. For instance, no air terminal can safely capture and arrest the lightning energy without a dependable route to earth. Equally, even the most expensive surge protection device (SPD) will not provide optimum protection if a low-impedance electrical connection to the earth is not present.
1. The most important reason is to help protect people.
2. To help provide protection of structures and equipment from unintentional
contact with live conductors.
3. To help support maximum safety from electrical system faults and lightning