1. Scope 1.1 This guide lists properties of an example of new high fire-point insulating oil of petroleum origin for use as a dielectric and cooling medium in new and existing power and distribution electrical apparatus, such as transformers and switchgear. 1.2 High fire-point insulating oil differs from conventional mineral insulating oil by possessing a fire-point of at least 300°C. This property is necessary in order to comply with certain application requirements of the National Electrical Code (Article 450-23) or other agencies. The material discussed in this guide is miscible with other petroleum based insulating oils. Mixing high fire-point liquids with lower fire point hydrocarbon insulating oils (for example, Specification D3487 mineral oil) may result in fire points of less than 300°C. 1.3 The material described in this guide may not be miscible with electrical insulating liquids of non-petroleum origin. The user should contact the manufacturer of the high fire-point insulating oil for guidance in this respect. 1.4 This guide is intended to give an example of a high fire-point insulating oil that is compatible with materials of construction of existing apparatus. This guide applies only to new insulating oil as received, prior to any processing. The user should contact the manufacturers of the equipment or oil if questions of recommended characteristics or maintenance procedures arise.