This standard applies to line post insulators with insulating parts of ceramic material intended for a.c. overhead lines with a nominal voltage higher than 1 000 V and a frequency not higher than 100 Hz. This standard applies to tie-top type line post insulators intended for vertical or horizontal mounting and clamp-top type line post insulators intended for vertical mounting and for horizontal mounting. This standard applies to line post insulators with normal creepage distance for use on overhead lines situated in clean or moderately polluted areas and to line post insulators with longer creepage distance for use on overhead lines situated in polluted areas. Note. - The extension of this standard to glass insulators may be considered later.