What is a Pet-Immune Motion Detector?

A pet-immune or pet-friendly motion detector is a type of passive infrared (PIR) motion detector that is designed to prevent false alarms from occurring. When a pet-immune motion detector is properly mounted, it will allow pets to walk freely through the protected area without setting off the device.

A PIR motion detector works by sensing the infrared energy signature of a potential intruder. Pet-immune motion detectors achieve their immunity by avoiding the detection of IR energy in areas where pets are usually found, such as the floor. These devices are intentionally designed this way to keep pets from setting off the motion detector and causing false alarms, while still being able to detect a human intruder.

There are several different pet immune motions available, each with different specifications. Some are rated for pets up to 40 lbs, while others provide immunity up to 80 lbs. However, pet-immune motion detectors are not perfect, and it is possible for these devices to be activated by pets if they are not mounted properly or if the pet is moving in an area where the motion detector can "see" it.

There are only a few ways to affect how much or how little a PIR motion can “see”. Mounting height, general placement, lens type and masking the lens can all affect the scope of detection. In some instances, the device may have a pulse count or a sensitivity setting that can be adjusted. All of these factors will help determine how sensitive the motion is to pets.

Most pet-immune motions require a mounting height of at least 7 feet. They are built with no “look-down” sensor, and their lenses are designed to detect in a pattern that does not include the floor. If there is a sensitivity setting on the motion, there will be a recommended setting for maximum pet-immunity. Their instructions will also come with a recommendation that the detector be mounted in such a way that no pet, regardless of size, can come within 6 feet of the front of the device by climbing stairs, drapes or furniture. Even the tiniest pet will cause a pet-immune motion to activate if it gets within 6 feet of the front of it, hence the 7-foot mounting height restriction.