Voltcraft et 100 insulation measuring device voltcraft et 100 p the voltcraft et 100 insulation device is able to measure resistance up to maximum of 4000m omega with test voltages 125 250 500 1000v in addition the et 100 offers the measurement functions for dc and ac voltages up to max 600v cat iii and for resistance in up to 400 omega br the soft moulded rubber protection around the device makes sure it is well protected p voltcraft et 100 insulation tester