This International Standard describes methods of test for the determination of the electrical breakdown potential of anodic oxidation coatings on aluminium and its alloys on flat or near-flat surfaces and on round wire. The methods are applicable to anodic oxidation coatings used primarily as electrical insulators. The methods are not applicable to coatings in the vicinity of cut edges, the edges of holes, or sharp changes of angle on, for example, extruded shapes. NOTE 1 The methods described do not give satisfactory results for unsealed coatings. NOTE 2 Electrical breakdown potential is affected by relative humidity.