GFI-501A Ground Fault Receptacle tester and circuit analyser. Tests ground fault breakers by overloading circuit and tripping GFCI. Easy to use, simply plug in and press black button to overload the circuit. Tests for seven condi-tions, open ground, open neutral, hot/ground reverse, hot/neutral reverse, correct wiring and ground fault interruption. Succession of yellow and red lights provide indication of circuit status or specify which wire is defective