After installing and switching on power, the detector is in operation state. When it detect smoke, the LED always light. SPECIFICAITONSOperating voltage:DC12V~ DC30V Static current::10μA~50μAAmbient temperature:-10~40degreesPower current should not exceed 30mAAfter installing and switching on power, the detector is in operation state. When it detect smoke, the LED always light.