This standard is applicable to: - ceramic and glass hollow insulators intended for general use in electrical equipment; - ceramic hollow insulators intended for use with a permanent gas pressure in switchgear and controlgear. These insulators are intended for indoor and outdoor use in electrical equipment, operating on alternating current with a rated voltage greater than 1000 V and a frequency not greater than 100Hz or for use in direct-current equipment with a rated voltage of greater than 1500 V.