Simply plug in this outlet tester and watch the red and amber indicators. Detects faulty wiring in 3-prong outlets. Plug in the receptacle tester for quick verification of your outlet's electrical circuit condition. It uses simple indicator lights (two amber, one red) to let you know if your circuit is operating correctly and is safe for use with your gear. Using the indicator lights, it will give you six results, letting you know that the circuit has:Open ground Open neutral Open hot Hot/ground reverse Hot/neutral reverse Correct