How Well Does PIR Pet Immunity Work?

I don't have much experience with residential applications, and my boss wants assurances that if he puts a PIR with pet immunity in his house, his 2 small cats will not cause false alarms. The application is within the spec (immunity to 30 lbs) of the product I am looking at (Bosch), but I am hoping someone has the experience to say that pet immunity typically works as advertised, or that mixing motion detectors with cats is asking for trouble.

Thank you!

Pet Immunity generally works, at least in my experience it does. I doubt those cats are close to the 30 pound threshold, so this application seems safe.

Often with 'Pet Immunity' designs, the sensor itself doesn't detect all the way to the surface of the floor, so animals close to the ground aren't detected.

In other cases, the sensor is designed only to trip if the blob of contrast being detected is a certain size. This is where the weight factor comes in. Under 30 pounds, the size and heat of an object is rather small, so even if the sensor detects movement, it just ignores it.

I have a cat (probably ~10 lbs.) and pet immune PIRs in my house. They're not Bosch, they're generic Z-Wave models, but they're also spec'd to 30 pounds.

I won't say I've had no false alarms, but they're infrequent. I may have had two since I installed them last November/December.

I'd also try and keep the PIR pattern aimed off the floor slightly, which further decreases the chance of a cat triggering one.

They normaly do work well. The issue we have seen is if you have furniture where the animals can jump up on or if you mount the motion near steps. This puts the animal above the "pet zone" and can trigger the motion detector. Keep this in mind when you install the motion and you should be fine.

So then could someone avoid triggering the alarm by crawling on the floor? ;)