One of the most powerful tools integrated in a Nimbus security system is the interlogix Wall Mount PIR Sensor. These sensors are quite effective, but we are often asked how they work. PIR detectors, or passive infrared motion detectors, measure the infrared energy of an area. PIR systems are not infrared cameras, they don’t see your shape as you walk into a room. Instead, these sensors detect sudden spikes in infrared energy such as the body heat of a large mammal. Infrared energy in any room fluctuates slowly, but the sudden entrance of a human or animal to the area is significant enough to trip the sensor. The interlogix 6540 pictured here can be set to Pet Immune mode. This means that cats and dogs, with significantly smaller bodies than their owners, are less likely to trip the sensors.