Proposes the adoption of IEC 99-4:1991 as an Australian Standard with the exception of Appendix AA. Applies to non-linear metal-oxide resistor type surge arresters without spark gaps designed to limit voltage surges on a.c. power circuits. Appendix GG modifies and supplements the proposed Standard to cover metal-oxide surge arresters with gaps for a.c. systems. Copies of IEC 99-4:1991 may be purchased from or viewed at any Standards Australia office.