Specifies the procedure for the selection of the standard withstand voltages for the phase-to-earth, phase-to-phase and longitudinal insulation of the equipment and the installation of three-phase a.c. systems having a highest voltage for equipment above 1 kV. It also lists the standardized values from which the standard withstand voltages shall be selected. This Standard is technically equivalent to, and has been reproduced from, IEC 71-1:1993.