LAP PIR MOTION SENSOR

What you need is to go on line and type in pir light bulbs. find a supplier buy one and just plug it into your light fitting. No wiring required.

You can fit a pir onto the ceiling and simply connect it into the existing light switch, exactly the same way that you'd wire a two way light switch. But electricity isn't really something you should be fiddling about with if you don't understand it. It will kill you.

A motion detector is a device that detects moving objects, particularly people. A motion detector is often integrated as a component of a system that automatically performs a task or alerts a user of motion in an area. Motion detectors form a vital component of security, automated lighting control, home control, energy efficiency, and other useful systems.

To get any use out of the pir, the circuit would need to be altered i.e. Existing switch removed from circuit (or given a different role) and wiring altered/added. Job for an electrician. Theres no such thing as a gifted amateur where electricity is concerned. Think safety. The idea is a sound one, I did a similar thing in my own home but left the existing landing light in place and added a single downlight operated by a pir. Best of both worlds.