Megger mit400 insulation tester megger mit410 en the megger mit410 insulation and continuity tester has been designed for electrical testing applications in the utilities industrial and commercial sectors and by domestic electricians its wide range of features makes the mit410 ideal for maintenance and service repair engineers a safety rating of cat iv 600 v makes them suitable for use in high energy systems up to the substation transformer while lower test voltages can be used in domest