Applies to post insulators and post insulator units of ceramic material or glass for indoor and outdoor service in electrical installations or equipment operating on alternating current with a nominal voltage greater than 1 000 V and a frequency not greater than 100 Hz. Notes: -May also be regarded as a provisional standard for insulators for use on d.c. systems, see IEC 60438. -When considering hollow insulators, see HD 329. -Tests on indoor post insulators of organic material will be covered by a future publication: Tests on indoor post insulators of organic material for systems with nominal voltages greater than 1 000 V up to but not including 300 kV. -For artificial pollution and radio-interference tests, see EN 60437 and 60507. -For numerical values for insulator characteristics and for selection of insulators for specific operating conditions, see EN 60273.