The earthing system is necessary for the safety and security of people and equipments and it is important as a preventive process to avoid the dangers of lightning strikes and static electricity or in case of any power transmission lines failure or fault current.
-IEC 60050-195:1998: International Electrotechnical Vocabulary - Part 195: Earthing and protection against electric shock -IEC 364-7-707: Electrical installations of buildings. Part 7: Requirements for special installations or locations.