Specifies requirements for non-linear metal-oxide resistor type surge arresters without spark gaps designed to limit voltage surges on a.c. power circuits. This Standard is based on and includes the full text of IEC 99-4:1991 with variations and additions for Australia included within the body of the text.RECONFIRMATION NOTICETechnical Committee EL-007 has reviewed the content of this publication and inaccordance with Standards Australia procedures for reconfirmation, it has beendetermined that the publication is still valid and does not require change.Reconfirmed documents cannot be amended, but may be formally revised and a newedition published.Certain documents referenced in the publication may have been amended since theoriginal date of publication. Users are advised to ensure that they are using the latestversions of such documents as appropriate, unless advised otherwise in thisReconfirmation Notice.Approved for reconfirmation in accordance with Standards Australia procedures forreconfirmation on 18 May 2015.Reconfirmed documents cannot be amended, but may be formally revised and a newedition published.The following are represented on Technical Committee EL-007:AusgridAustralian Industry GroupEnergy Networks AssociationEngineers AustraliaThe University of New South Wales