Monitoring of an electrical component

The method involves operating an electrical component (1) comprising error notifying unit (2), by supplying power from switching power supply (6) via supply lines (4). Rectifier element (7) arranged in specific supply line is configured to actuate switch (S) in error notifying unit. The error or fault generated in electrical component is passed via rectifier element, and detected using detection device (8). An independent claim is included for a circuit device for monitoring electrical component.