This European Standard 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 a.c. and nominal frequency up to and including 60 Hz, so as to provide safety and proper functioning for the use intended. For the purpose of interpreting this standard, an electrical power installation is considered to be one of the following: a) substation, including substation for railway power supply; b) electrical 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 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.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 In general, a standard for an item of equipment takes precedence over this standard.This European Standard does not apply to the design and erection of earthing systems of any of the following:– overhead and underground lines between separate installations;– electric railways;– mining equipment and installations;– fluorescent lamp installations;– installations on ships and off-shore installations;– electrostatic equipment (e.g. electrostatic precipitators, spray-painting units);– test sites;– medical equipment, e.g. medical X-ray equipment. This European Standard does not apply to the requirements for carrying out live working on electrical installations.