Extech CB20 Circuit Breaker Finder / Receptacle Tester.

Circuit Breaker Finder/GFCI Receptacle Tester
Locate the correct circuit breaker or fuse without turning off the power with the Extech CB20 Circuit Breaker Finder, which employs automatic sensitivity to quickly and accurately pinpoint the correct 90V to 120VAC circuit breaker or fuse. The CB20 is ideal for a range of applications, including locating branch circuit breakers without causing accidental power shutoffs, confirming proper wiring during electrical installation or repair, and testing receptacle ground fault operation.

CB20 Overview
Simply plug the transmitter into an outlet and trace for the correct breaker at the electrical box. The CB20 transmitter's bright red and green LEDs indicate if the receptacle is correctly wired or will indicate which of the two test conditions and six fault conditions exists. Other features include push-button GFCI testing, plus audible and visual circuit breaker indication.