Extech Extech GFCI Receptacle Tester, ET10, 120V AED55.75 (Incl.VAT) The ET10 is a GFCI Receptacle Tester which is used for testing GFCI circuits for faulty wiring in 3-wire receptacles. Tests for faulty wiring in 3-wire receptacles: Correct, Open Ground, Open Neutral, Open Hot, Hot/Ground Reverse, and Hot/Neutral Reverse... Available on Request