Motion sensors provide additional home security by alerting you when someone or something crosses a designated area inside your home. When combined with indoor wireless security cameras, or other home security options, motion sensors are a great complement to an existing security system.

Many modern motion sensors are built for homes with pets, allowing you to adjust the sensitivity level so they don’t recognize cats or dogs. 

This pet immunity helps prevent false alarms.

This article will cover different motion sensors and dive into the key difference between sensors like an active sensor and a PIR sensor.


What are motion sensors?


A motion detector, aka motion sensor, detects movement. Motion sensors are used in many security applications. For example, a light turns on when movement is detected, or an alert gets sent to your phone or the police if someone crosses the sensor.

Motion sensors are not just used in security, but we also use them in our daily lives. Whenever your smartphone’s orientation changes as you move it, or when you place your hands beneath an automatic paper towel dispenser or a cup under your fridge’s water spout, motion sensors are working to make your life easier.

ADT’s pet-immune motion sensors are packed with features to help protect your home.

  • Sleek design seamlessly integrates into your decor and lifestyle.

  • Maximum 40x56 feet of coverage.

  • One thousand feet line of sight from the command panel.

  • Programmable pet immunity up to 80 lb.

  • If the sensor detects motion, you’ll automatically receive a triggered alert and video.

  • Uses passive IR technology to signal your alarm panel if motion or body heat is detected in your destinated coverage area.

  • Detector supports over-the-air firmware updates for future enhancements.

  • Five-year battery life with typical use.


How do motion sensors work with pets?

You may worry that a pet will set the sensor off, triggering a false alarm. Newer systems now can ignore anything under 85 pounds, so most pets are off the hook. In fact, with ADT’s motion sensors, you can set the sensitivity level to the specific weight of your pet.

Many of these sensors use PIR motion-detecting technology, which uses infrared light reflected from other objects. Sometimes, these sensors can ignore your pet up to a specific size or allow you to disregard just a single large dog or even multiple small cats.

A traditional motion sensor gets tripped by anything that crosses its sensors, including your pets. This increases the potential for false alarms, so if you own a cat or dog, a pet-immune sensor is perfect for your home.



What is a PIR motion sensor? 

A PIR motion sensor is also known as a passive infrared sensor. These sensors measure infrared lights from other objects, but they don’t emit their own LED light.

Because they’re good at sensing movement, you’ll find them used in applications for automatic or smart lighting, security alarms or motion detectors.

How does a PIR motion sensor work?

An active infrared sensor shoots out a light beam towards the receiver. If nothing is blocking the receiver, the sensor sees the signal and determines nothing is in the room. If the receiver doesn’t see the IR beam and an object is between them, it alerts you.


What is an active IR sensor?

An IR sensor has a light-emitting diode (LED) and a receiver. It works by using the LED light reflected from an object bounced back and sensed by the receiver.

These sensors detect obstacles and are used in robots, night vision devices, and radiation thermometers. Meteorologists and climatologists use IR sensors frequently in their work, too.


Where should you install pet motion sensors?


The best placement for a pet sensor is in a high corner of the room, about 6 to 8 feet away from the ground, so that they can cover as much area as possible. (We recommend 7.5 feet.)

Avoid placing them:

  • Near a door or window, which could block their range.

  • Near a heating element, since many sensors use infrared features and a heater could cause a false alarm.

  • Aimed towards windows, fireplaces, air conditioners, area heaters, forced air heating vents or drapes.

  • In direct sunlight as sudden changes in temperature may trigger a false positive.

  • Near ductwork or other large metallic surfaces may affect the RF signals. 

  • Outdoors or in a non-temperature controlled environment.  

  • On a shelf.



Motion detectors and cats:


Cats are smaller than many dogs and prone to climbing or jumping around, so they may be more likely to trigger a false alarm. To potentially reduce this, get an IR sensor since they sense heat, not movement. The best way to reduce it is to ensure that your new motion detector is pet immune.

Where to place motion detectors when you own a cat?

A great thing about motion detectors is that you can move them around the home. Test spots out to determine what works best for the number of cats you have. Alternatively, you can also have a professional install your equipment for you.

Here are a few tips to help reduce false alarms when you own a cat:

  • Mount sensors where there aren’t things for your cats to jump on.

  • Install detectors high up on walls, where cats aren’t likely to be caught on the sensor.

  • Adjust the sensitivity if you have multiple cats, especially if they often play around together.

  • If these tips don’t work, you might be better off only adding a motion detector in the entryways.

  • Keep an indoor camera rolling, so you’ll know if your pet is setting off your camera or something else is doing that.


Motion detectors and dogs:


Dogs come in all shapes and sizes, from the tiny chihuahua to friendly golden retrievers. No matter what shape and size your pups come in, a motion detector helps protect you and them.

Just like with cats, the best way to reduce potential false alarms is to make sure your new motion sensor has pet immunity.

Where to place motion detectors when you own a dog:

Your furry friend is a part of your family, so you want to factor them into your alarm system. We’ve compiled a few tips to help prevent pet owners with dogs from experiencing false positives.

  • Consider adding doggy gates to block off rooms when you’re out of the home to reduce false positives.

  • Avoid pointing sensors towards stairs since your pet may set off the sensor.

  • Add an indoor camera to verify what is setting your alarm off.



At ADT, we love our pets. 


That’s why we’ve made sure our motion sensors account for them. 

Take your home security to the next level with sensors that ignore pets up to 40 pounds. No matter how many four-legged family members you have, ADT home security will work with you to create the perfect home security package.


Frequently Asked Questions about Pets and Motion Sensors

Do animals set off outdoor motion sensors?

Anything that crosses the outdoor sensors will set them off, whether a dog, cat, raccoon or another animal. Many outdoor motion detectors allow you to adjust the settings so your sensor doesn’t detect specific sizes.

To help prevent animals from triggering a false alarm, be mindful of where you place your outdoor sensors.


Can you have a security system with pets?

Many motion sensors, like the ones ADT offers, are designed so pets don’t trigger them. Once the system is armed, you’re free to let your cat or dog roam! ADT’s sensors allow you to set the sensitivity of your motion sensors up to 80 pounds.  


What to do if your pet keeps setting off your motion sensor?

If your motion sensor keeps getting triggered by your pets, try moving it to a higher or different location. And if that doesn’t work, you may need to block off the room where your sensors are from your pets.


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