Although the principles of this part also apply to transmission line insulation, the values of
the withstand voltages may be different from the standard withstand voltages.
The apparatus committees are responsible for specifying the withstand voltages and the
test procedures suitable for the relevant equipment taking into consideration the
recommendations of this Standard.
NOTE - In IEC 71 -2 Application Guide, (under revision), all rules for insulation co-ordination given in this
Standard are justified in detail, in particular the association of the standard withstand voltages with the
highest voltage for equipment. When more than one set of standard withstand voltages is associated with
the same highest voltage for equipment, guidance is provided for the selection of the most suitable set.