The instrument is a bench-type ground circuit tester. The GF-25A features automatic one button operation, with PASS or FAIL test result indicated by lights on the front panel and an internal buzzer. A supervisor-adjustable test duration circuit allows the test to continue for a predetermined amount of time after the Test Button has been released. The instrument advises the operator of any internal malfunction affecting the output. A one-time setup procedure allows the instrument to compensate for lead resistance, allowing the instrument to measure the true resistance of the grounding circuit of the equipment under test. The GF-25A meets TÜV criteria for automatic production line ground circuit testers.