This recommended practice outlines a test procedure for the evaluation of the impulse voltage capability of insulation systems of form-wound alternating current rotating electrical machinery. This test procedure forms a base for the accumulation, analysis, and reporting of information concerning impulse voltage withstand strength of ground and turn insulation, both new and aged. The immediate goal is a better understanding of relevant aging mechanisms; the ultimate aim of this document is to aid in estimating life of an insulation system under specified service conditions.It must be emphasized that this test procedure is intended, at this time, for trial use. Future revisions, made after experience with it, should result in more definitive specifications being possible.