This document is applicable to specify the requirements for the design and erection of earthing systems of electrical installations, in systems with nominal voltage above 1 kV AC and nominal frequency up to and including 60 Hz, so as to provide safety and proper functioning for the use intended. NOTE 1 – The technical and procedural principles of this document can be applied when 3rd parties’ installations and facilities are planned and/or erected in the vicinity of HV electrical power installations. For the purpose of interpreting this document, an electrical power installation is considered to be one of the following: a) substation, including substation for railway power supply; b) electrical power installations on mast, pole and tower; switchgear and/or transformers located outside a closed electrical operating area; c) one (or more) power station(s) located on a single site; the electrical power installation includes generators and transformers with all associated switchgear and all electrical auxiliary systems. Connections between generating stations located on different sites are excluded; d) the electrical system of a factory, industrial plant or other industrial, agricultural, commercial or public premises; e) electrical power installations on offshore facilities for the purpose of generation, transmission, distribution and/or storage of electricity; f) transition towers/poles between overhead lines and underground lines. The electrical power installation includes, among others, the following equipment: – rotating electrical machines; – switchgear; – transformers and reactors; – converters; – cables; – wiring systems; – batteries; – capacitors; – earthing systems; – buildings and fences which are part of a closed electrical operating area; – associated protection, control and auxiliary systems; – large air core reactor. NOTE 2 – In general, a standard for an item of equipment takes precedence over this document. This document does n ...