BS CP 1013:1965

Methods for earthing electrical systems: 'system earthing' (i.e. limiting the potential above earth of the current-carrying conductors); and 'equipment earthing' (i.e. limiting the potential of non-current-carrying metalwork, to ensure the safety of human life, animals and property). Earth-electrodes, power stations, substations, overhead power lines, protective earthing, consumer's premises, tramways, railways, trolley-bus systems, inspection, testing and maintenance. Ships and aircraft are not cover ed.