Diagnose the fault in a low voltage distribution box by checking for overheating, loose connections, and using voltage testers for safe troubleshooting. Always turn off the power before you start any inspection. If your circuit breaker is on, but no power is getting to your outlet, light, or appliance, there is a simple process to go through in order to find the culprit. As a 29-year seasoned electrician, I'll walk you through exactly how I always approach the issue. Make sure the power supply is. By learning how to use a multimeter to test your breaker box, you can diagnose problems quickly and accurately, saving you time and money on costly repairs.