The Extech 380363 insulation tester measures up to 10 G-Ohm with 250V, 500V and 1000V Test Voltages. Features include: Lo-Ohms for testing connections, analog bargraph for viewing trends, AC/DC Voltage measurement to 999V, manual data record/recall function (9 sets), and live circuit display warning and beeper. Can be used to test motor, transformer windings, instruments, and appliances, check for moisture in wire and cable assemblies, safely evaluate a new wiring installation, and check for carbon tracking in breakers, relays, and switches. Extech Insulation Testers offer high sensitivity to assure reliable monitoring of low resistance motor windings.