Does My ADT Motion Sensor Have Pet Immunity?
- Pet-immunity rating varies by sensor model (e.g. 40 lb vs 80 lb)
- Pet heavier than the sensor's rating
- Sensor mounted too low, in the pet's path
Problem Description
You want to know if your ADT motion sensor has pet immunity so it won't trigger false alarms from pets. Pet immunity varies by sensor model — some ignore animals up to 40 lbs, others up to 80 lbs. Check the model number on the back of the sensor. This guide covers identifying your model and its pet immunity rating.
Why This Happens in Real Homes
Pet immunity isn't a single feature that's simply on or off across ADT sensors - it's a rating that varies by model, with common thresholds around 40 pounds or 80 pounds. So the first thing to do is identify your exact sensor by the model number on the back and look up its pet-immunity rating, because a sensor rated for 40 lb will reliably ignore a cat or small dog but can be triggered by a large dog. If your pet is heavier than the rating, no amount of adjustment fully fixes it, and the right move is upgrading to a higher-rated pet-immune model.
How pet immunity actually works is by geometry as much as electronics: pet-immune PIR sensors are designed with a detection pattern that looks out and slightly up, so a person walking is detected while an animal on the floor stays below the active beams. That means mounting matters enormously - install the sensor at the recommended 7-8 foot height and angle so pets remain beneath the detection zone. The common failure isn't the rating but placement: a sensor mounted too low, or angled down at the floor, or positioned where a pet can climb onto furniture and into the beam, will false-alarm regardless of its rating. Enable pet-immunity mode if your model has a setting, keep furniture out of the zone, and do a test with your pet moving around after setup to confirm it behaves.
Symptoms
- Unsure if the sensor ignores pets
- Pet triggers false alarms
- Want to confirm the pet-immunity weight rating
- Adding a pet to a home with existing sensors
- Large pet setting off the alarm
- Small pet occasionally triggering it
- Checking the sensor model number
- Deciding sensor placement for pets
Recognize these? Here's what usually causes it.
Common Causes
- Pet-immunity rating varies by sensor model (e.g. 40 lb vs 80 lb)
- Pet heavier than the sensor's rating
- Sensor mounted too low, in the pet's path
- Pet climbing on furniture into the detection zone
- Model doesn't support pet immunity
- Pet-immunity mode not enabled in settings
- Multiple pets adding up past the threshold
- Sensor angled down toward the floor
Most fixes happen in the first 3 steps.
Always notify your monitoring provider before performing system tests to prevent dispatching emergency services unnecessarily. Never disable your security system for extended periods. If you smell gas or suspect a real emergency call 911 directly rather than relying on your smart system.
Tools & Requirements
These tools will help you complete this fix.
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Step-by-Step Solution
Check your sensor model for pet immunity rating
ADT offers motion sensors with different pet immunity levels. Standard pet-immune sensors ignore animals up to 40 lbs. Some models handle up to 80 lbs. Check the sensor model number on the back of the device and look up its pet immunity rating. If you have a large dog (over the sensor rating), the sensor will trigger on the dog and cause false alarms. You may need a sensor upgrade for larger pets.
Mount the sensor at the correct height
Pet-immune motion sensors are calibrated for a specific mounting height — typically 7-8 feet. The sensor lens is designed to ignore heat signatures at floor level (where pets are) and detect them at human height. If mounted too low (4-5 feet), the sensor sees pets at a closer, larger scale and treats them as human-sized. If mounted too high (above 9 feet), the detection pattern shifts and may miss humans or false-trigger on large pets.
Angle the sensor away from pet areas
Even with pet immunity, a sensor pointed directly at a pet bed, food bowl, or cat tree can false-trigger when the pet moves vigorously. Angle the sensor so pet areas are at the edge of the detection field, not the center. Avoid mounting where a pet can jump onto furniture and be at sensor height — a cat on a bookshelf is at human height and will trigger any PIR sensor regardless of pet immunity settings.
Keep pets away from the sensor lens
A pet directly in front of the sensor (within 3-4 feet) appears much larger to the PIR lens than it actually is and can trigger even a pet-immune sensor. If your pet sleeps near the sensor or walks directly under it frequently, relocate the sensor to a spot where the pet's path is at least 6-8 feet away from the sensor. Pets crossing the far edge of the detection zone are much less likely to trigger than pets close to the sensor.
Replace with a dual-technology sensor
If false alarms from pets continue with a standard PIR sensor: upgrade to a dual-technology motion sensor. These combine PIR (heat detection) with microwave detection. Both technologies must trigger simultaneously for the alarm to activate. A pet triggers the PIR but not the microwave, so the alarm does not fire. Contact your ADT dealer or technician to install dual-tech sensors in rooms where pets cause repeated false alarms.
Quick Solutions
Still having issues? This is usually the deeper cause below.
If the sensor still misses events after repositioning, check whether a scheduled 'home' or 'away' mode is overriding the sensitivity setting silently.
Set up geofencing so your system arms automatically when everyone leaves home and disarms when the first person returns. This eliminates the chance of forgetting to arm the system and provides seamless daily security.
Pet immunity is optimistic marketing — it assumes the sensor is mounted at the correct height, which almost nobody gets right on first install.
- Pet-immunity rating varies by sensor model (e.g. 40 lb
- Pet heavier than the sensor's rating
- Sensor mounted too low, in the pet's path
- Pet climbing on furniture into the detection zone
- Model doesn't support pet immunity
Before you go — try one of these (they fix most cases).
Official Manufacturer Manual
ADT provides official product documentation through their online manual rather than downloadable PDF. Access setup guides, troubleshooting steps, and product specifications for your ADT Motion Sensor.
Source: help.adt.com
Need More Help? ADT Support
Note: The contact information below connects you directly to ADT's official customer support team, not Trunetto. They can help with warranty claims, device replacements, and advanced technical issues.
Accessories owners commonly pair with ADT Motion Sensor.
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