2. Resistance of materials to various dielectric stresses

Since air withstand conditions the external dimensioning of electrical installations, we will deal more specifically with the withstand of insulation in air and that of creepage distances along external insulation. Similarly, for equipment insulated with sulfur hexafluoride (SF ₆ ), we give the essentials of the dielectric properties needed to coordinate insulation. On the other hand, with regard to the internal insulation of equipment, whether solid, liquid or composite (paper in oil, etc.), we give only a few indications, as they are difficult to generalize for the coordination of insulation, referring for more details to the specialized articles in this treatise.