This standard describes methods for the determination of water in insulating liquids and in oil-impregnated cellulosic insulation with coulometrically generated Karl Fischer reagent. The method in clause 2 is applicable to water concentrations above 2 mg/kg in liquids having viscosity less than 100 mm2/s at 40°C. The test method in clause 3, where water is extracted by means of a nitrogen stream, is the preferred method for insulating liquids of viscosity higher than 100 mm2/s.