MEGATESTER: Electrical Unenergized Circuit Tester LED Tests unenergized circuits from 3v to 220v. Tests switches, fuses, cords, circuit breakers, tools, and much more. Troubleshoots electrical problems in less than a minute Doubles as a Flashlight - Cree Q3 LED bulb. 50,000 hours of life. Lifetime Guarantee - Tested and listed as safe by the UL