Megger mit200 insulation testers megger mit220 en the megger mit220 insulation tester is a tough and compact pocket sized instrument which is safe and functional the bright clear lcd displays readings in concise digital form but also simulates an analog pointer response for evaluating circuit charge and discharge characteristics if it detects voltages in excess of 25v acdc it will generate a voltage warning circuits over 50v acdc will inhibit the insulation test protecting the operator