Lamp-preserving zero-voltage switching (longer service life). Staircase light function with premature restart of the illumination time: Upon activating the sensor the output contact closes and upon opening the sensor the pre-selected time starts to run. Upon each activation of the sensor during the pre-selected time, the timer is restarted. After the last activation of the sensor and after the pre-selected time has elapsed, the light is switched off. Service function: Upon activation of the sensor for more than 5 s the output contact closes for 60 minutes, whereby the time can be shortened prematurely by more than 5 seconds by activating the sensor again. After the last activation of the sensor and after the pre-selected time has elapsed, the light is switched off. This function is ideal for maintenance and cleaning in the staircase. For 3 or 4-wire connection with automatic adjustment. Module type for 35 mm. DIN rail mounting.