This International Standard gives guidance on the supervision and maintenance of the qualityof 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 cod