ASTM D495 is the “tandard Test Method for High-Voltage, Low-Current, Dry Arc Resistance of Solid Electrical Insulation”. The test is used as a preliminary screening method to compare how solid insulating materials resist degradation when exposed to a high-voltage, low-current arc near the material surface. The arc can thermally and chemically decompose the insulation, erode the surface, and eventually form a conductive carbonized track. In practical terms, the test measures the time required for the material surface to lose insulating integrity under dry, clean, controlled laboratory arcing conditions.
In the test, electrodes are positioned over or near the surface of the insulating specimen and a controlled high-voltage, low-current arc is applied; The result is commonly reported as arc resistance time, not as a direct service-life prediction. For aerospace or EWIS use, ASTM D495 is best treated as a comparative material-screening data point that should be supported by application-specific testing.
