A sensor system that constantly monitors an irradiance level of a UV lamp and is operated by power from a sensor thereof, wherein the UV lamp is powered by a ballast. The sensor system includes a current sensor, a UV sensor, a voltage comparator, and a display. The current sensor is disposed in the electronic assembly and picks-up current from the ballast, and in response thereto, powers the voltage comparator. The UV sensor is disposed externally to the assembly and picks-up the irradiance from the UV lamp. The voltage comparator is disposed in the electronic assembly, is in electronic communication with the current sensor and the UV sensor, is powered by the current sensor, and compares voltage from the UV sensor to a predetermined value. The display is visible from the electronic assembly, is in electronic communication with the voltage comparator, and indicates result of comparison of the voltage comparator to thereby determine status of the UV lamp.