An aliphatic polyamide film or fibrous material is employed for electrical insulation in individual conductors, groups of conductors, magnet wire, magnet wire coils, and layers in liquid filled electrical transformers. The material is stabilized with additives that produce improved moisture resistance, moisture stability, thermal stability, thermal conductivity, reduced insulation thickness, reduced shrinkage, and improved insulation elasticity for the insulation material thereby providing a longer useful life for the material.