This International Standard deals with impulse puncture testing in air of ceramic and glass insulator units of class B (see IEC 60383-1): cap and pin, pin type (including pin-post type) and class B long rod insulators. This standard may be applied also in tests on Class B insulators of other materials (e.g. polymers and composites). However, it may be useful to consider the possible need to adjust the test procedure accordingly. This standard is published with the object of specifying a standard procedure for impulse voltage puncture tests on insulators in air. Both type and sample test procedures are given