What does the LUX knob do on the motion sensor?

The LUX dial controls the natural light level that initiates operation and prevents the security light from operating during daylight hours. 

 

When set to the highest level the light will continue to work even in daylight, we recommend that the dial be turned counter clock wise and leave it set 1/4 of the way, this way the light will only work at night and remain off during day time hours.