There are 4 wires , is Live wire (L); the outermost line is Neutral wire (N);Yellow line and inside line connect to light bulb or -saving lamp . Function: Auto switch on/off in the dark when you enter into the induction range, and the time delay has 3 way of 15 seconds, 45 seconds, 5 minutes adjustable.In addition to the automatic control of LED lights, it can also be used to control exhaust fans, doorbells or other devices. Infrared Sensor Switch working voltage: 100-240V ;Best sensing distance:3-5M ; Mounting Hole Diameter:25mm/0.98inch PIR motion sensor switch has feature of small size and , easy to install and operate in room or cabinet, plug and play. Widely Suitable for auto lighting corridors, stairs , bathrooms, basements, warehouses, garages,closet, advertisement light and other places.