The most frequent culprit is a burnt-out light bulb, which should be replaced with a known working model of the correct wattage and base type. A loose bulb that has vibrated out of its socket will also cut the electrical path; tightening it gently may restore power. A non-functioning light fixture is a common household issue. Before diagnosing the problem, recognize the hazards of residential electrical systems. Any physical inspection of wiring or components must begin by switching off the power at the main circuit breaker panel. This safety step prevents. 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.