This standard specifies tie-top type and clamp-top type porcelain linebost insulators (hereinafter referred to as insulators), and applies to the following insulators. a) Tie-top type insulators, which were previously specified by JIS, are specified in the main body of this standard. b) Tie-top type and clamp-top type insulators for AC overhead lines with a nominal voltage exceeding 1000 V and a frequency lower than 100 Hz as specified in IEC 60720. Specified in the Annex (Regulations) to this standard. Note that either the main body or annexes (regulations) of this standard shall be used consistently for one product, and the corresponding provisions and contents of both may be selected or mixed as appropriate. cannot be applied.