Provides, in a convenient form, common rules for the design and the erection of electrical power installations in systems with nominal voltages 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.This standard applies to all high voltage installations except as stated otherwise in some cases specified in other parts of IEC 61936.This standard does not apply to the design and erection of any of the following:- overhead and underground lines between separate installations;- electric railways (but not the substation feeding a railway system);- mining equipment and installations ;- fluorescent lamp installations;- installations on ships and off-shore installations;- electrostatic equipment;- test sites;- medical equipment, e.g. medical X-ray equipment.This standard does not apply to the design of factory-built, type-tested switchgear for which separate IEC standards exist.This standard does not apply to the requirements for carrying out live working on electrical installations.For the purpose of interpreting this standard, an electrical power installation is considered to be one of the following.a) SubstationA closed electrical operating area in a transmission or distribution network. When switchgear and/or transformers are located outside a closed electrical operating area, this is also taken to be an installation.b) One (or more) power station(s) located on a single siteThe installation includes generators and transformers with all associated switchgear and all electrical auxiliary systems. Connections between generating stations located on different sites are excluded.c) The electrical system of a factory, industrial plant or other industrial, agricultural, commercial or public premisesConnections between closed electrical areas (including substations), located on the same site, are taken to be part of the installation, except where such connections form part of a transmission or distribution network.The electrical power installation includes, among others, the following equipment:- rotating electrical machines;- switchgear;- transformers and reactors;- converters;- cables;- lines;- 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 type core reactor.NOTE In general, a standard for an item of equipment takes precedence over this standard.