IEC/TS 80815-1:2008(E) applies to the selection of insulators, and the determination of their relevant dimensions, to be used in high-voltage systems with respect to pollution. This part of IEC 60815 gives general definitions, methods for the evaluation of pollution site severity (SPS) and outlines the principles to arrive at an informed judgement on the probable behaviour of a given insulator in certain pollution environments. This first edition of IEC/TS 60815-1 cancels and replaces IEC/TR 60815, which was issued as a technical report in 1986.