This guide is intended for use in establishing a methodology to evaluate expected long-term performance of infrequently operated switch contacts used within insulating liquid–immersed transformers. These switch contacts are typically found in de-energized tapchangers, dual voltage switches, reversing switches, on-load tapchangers, and step-voltage regulators, but the test might possibly be used to evaluate any contact that is used in insulating liquids with similar operating characteristics and within similar environments.