This is due to the tester having ‘Fixed limits’; where there are two limits the tester will test to the lower limit. Table 15.3 on page 77 of the IEE Code of Practice 3rd edition indicates that Portable or Hand Held class I appliances should not exceed 0.75 mAmps while IT, Movable and Stationary class I appliances should not exceed 3.5 mAmps; the KT71 is set to the lower limit of 0.75.
For IT, Movable and Stationary class I appliances, as long as the reading does not exceed 3.5 mAmps, you can pass the appliance on the leakage test even though the tester indicates a fail. Just press the ‘START’ button to continue.
