1 hour ago, Terry Hunter said:

Site has been live for two years and it was set hence activating when the Police went it - my thoughts a mixture of the beams set as being default medium sensitivity and the intruder being fully covered.

So you have beams not pirs?

 

1 hour ago, PeterJames said:

Infra red radiation is anything that sends out heat - basically has a temperature above around five degrees Kelvin - gives off infrared radiation. Therefore passive infra detector is looking for heat changes, but it is also looking for motion.  

I knows, but you said:

 

"Infra red is the detection method NOT what the detector is looking for, infra red detector detects heat or INFRA RED radiation"