Product Description The Task Of Locating Ac Circuits Is Now Made Quick And Easy Thanks To Ideal Electrical. No More Guessing Or Trial And Error When It Comes To Locating The Correct Circuit Breaker Supplying Power To An Ac Outlet Or Lighting Fixture. Positively Identifies Circuit Breakers And Fuses Without Service Interruption. Digital Receiver & Gfci Circuit Tester. Non-Contact Voltage Sensor From 80-300Vac Automatically And Quickly Finds Correct Breaker. Transmitter Works On 120Vac Circuits. Proper Wiring Is Crucial To Ensure Safety And Performance Of Branch Circuits. From A Safety Perspective, Shock Hazards And Fires Are Mainly Due To Poor Installation Or Failure Of Protective Devices, Such As Gfcis. If The Receiver Is Left On And Not Utilized For 10 Minutes (No Energized Ac Circuit Or Transmitter Signals Are Detected), It Will Automatically Shut Down To Conserve Its Battery Life. From the Manufacturer IDEAL 61-534 Circuit Breaker Finder with GFCI Tester