Tests ground fault breakers by overloading circuit and tripping GFCI. Plug tester into any ground fault receptacle (110-125 volt AC) and press black button to overload circuit. Tests for seven conditions; ground fault interruption, open ground, open neutral, open hot, hot/ground reverse, hot/neutral reverse and correct wiring. Yellow and red lights provide indication of circuit status or specify which wire is defective. Carded.