Gives guidance on the supervision and maintenance of the quality of the insulating oil in electrical equipment. This standard is applicable to mineral insulating oils, originally supplied conforming to IEC 60296, and used in transformers, switchgear and other electrical apparatus where oil sampling is reasonably practicable and where the normal operating conditions specified in the equipment specifications apply. This standard assists the power equipment operator to evaluate the condition of the oil and maintain it in a serviceable condition. It also provides a common basis for the preparation of more specific and complete local codes of practice. This standard includes recommendations on tests and evaluation procedures and outlines methods for reconditioning and reclaiming oil and the decontamination of oil contaminated with PCB. NOTE The condition monitoring of electrical equipment, for example by analysis of dissolved gases, furanic compounds or other means is outside the scope of this standard. The main changes with regard to the previous edition are as follows: This standard has been revised to take into account changes in oil and equipment technology and to have due regard for the best practices currently in use world-wide. The action limits for all oil tests have been revised and changes made where necessary to enable users to use current methodology and comply with requirements and regulations affecting safety and environmental aspects. This guidance incorporates changes introduced in associated standards since the publication of the second edition.