The concept of an outlet tester is pretty simple: plug the gadget into a suspect wall receptacle, and an array of LEDs light up in various patterns to alert the user to any wiring faults. They&#821… ...

Turn Off Power at the Main Circuit Locate the circuit breaker or fuse that controls the outlet you plan to replace and shut off the power to the circuit. Plug a lamp, radio or the GFCI tester into ...

Often called a “cube” or “block” tester, this device simply plugs into an outlet and displays lights that indicate the most common outlet wiring issues.