This guide describes methods of testing and specifications for electrical insulating oils of petroleum origin intended for use in electrical cables, transformers, oil circuit breakers, and other electrical apparatus where the oils are used as insulating, or heat transfer media, or both. This guide is classified into the following categories: sampling practices, physical tests, electrical tests, chemical tests, and specifications. The test methods shall be as follows: aniline point; coefficient of thermal expansion; color; examination; flash and fire point; interfacial tension; pour point of petroleum products; refractive index; relative density; specific heat; thermal conductivity; turbidity; viscosity; dielectric breakdown voltage; dissipation factor and relative permittivity; gassing tendency; resistivity; stability under electrical discharge; acidity; carbon-type composition; compatibility with construction material; copper content; furanic compounds; gas analysis; gas content; inorganic chlorides and sulfates; neutralization numbers; oxidation inhibitor content; oxidation stability; polychlorinated biphenyl content; sediment and soluble sludge; sulfur; water content; mineral insulating oil for electrical apparatus; and high firepoint electrical insulating oils.