How to effectively place motion sensors in your home

Every motion sensor in your home is like an extra set of eyes watching the places you can’t see, so it’s important to make sure each sensor has a clear line of sight. We’ll give you a brief overview of how motion detectors work and a few tips on where to position motion sensors in the home like a pro.

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The most common type of motion sensor used in home security is a passive infrared sensor, otherwise known as a PIR sensor. PIR sensors send out rays designed to detect heat. The sensor’s rays fan out, so they’re most concentrated right next to the sensor, and become less sensitive farther away from the sensor. The rays can’t detect heat through walls or furniture, so it's important to place these sensors where the rays are clear of obstacles.

Less common are microwave sensors, ultrasonic sensors, vibration sensors, and area reflective type sensors. Dual technology sensors combine PIR technology and microwave technology for fewer false alarms. To learn more about how motion sensors work and the role they play in a home security system, read our Beginner's Guide to Motion Sensors.

You know those areas of your home where the flooring gets worn down the most because everyone walks through them? Those are great locations for motion sensors because an intruder will have to walk through those spots as well. 

Imagine you’re trying to get a good photograph of a large room. Where would you stand to take it? Yup, a corner. The same location that gives you the widest view of a room will give your sensor a good view of the room as well.

You want your motion detector to get a birds-eye view of the space, but placing it too high can lead to blind spots down low. About two metres up on the wall is the sweet spot for most motion sensors. You can put a motion sensor on the ceiling, but first make sure it has a full 360-degree viewing angle. 

You know how pranksters like to position buckets of water over doorways to drop on unsuspecting victims? You can use that same technique to keep your motion sensors out of intruders’ sight by placing them just over an exterior door inside your home. They won’t know it’s there until it’s already sounded an alarm. 

Basement windows and doors are prime entry points for intruders who want to stay off your radar. Motion sensors work great in basements because most basements have wide spaces with few barriers and they don’t heat up like garages do.

Catch thieves red-handed by placing motion sensors behind valuables. This makes the sensor blind to movement unless the crook moves the object and reveals themselves to the motion sensor, triggering an alarm.

Putting your active sensors in the wrong location can lead to blind spots and false alarms. Here are a few sensor locations to avoid.

Think of your infrared motion detection beam like a torch beam. If you place it above a piece of tall furniture that sticks out far from the wall, the furniture could create a “shadow” or a blind spot. Avoid putting motion sensors on a wall near the top of a bulky entertainment center, wardrobe, or other large piece of furniture.

Motion sensor infrared works by detecting sudden changes in temperature. Putting a motion sensor near a heating vent, oven, light fixture, or anywhere else likely to have a sudden increase in temperature is a recipe for false alarms.

Unless you're lucky enough to have double-glazed windows, you should also avoid placing sensors where they could heat up from the sun.

Again, motion sensors use their infrared beams for high temperature detection, so it’s a good idea to avoid putting them in non-climate-controlled spaces that might heat up, like garages, attics, patios, and sunrooms. Consider alternative security solutions for these spaces, like door and window sensors, glass break sensors, or a security camera.

If you have pets and you don’t want your motion sensors to get triggered by your dog or cat, avoid putting sensors at the top of stairs. As your pet climbs the stairs, it will look bigger to the motion detector and it could set off an alarm.

While it’s a good rule of thumb to avoid putting motion sensors across from doors, it’s really dependent on your home’s layout. Remember that PIR sensors can’t see through walls, so you may be limiting a sensor’s detection scope if you put it directly across from a doorway in a confined area.

It’s easy to think of a motion sensor as a standalone home security device to guard against intruders, but pairing motion detection technology with other smart tech can help you save on energy bills, keep family members safe, and streamline your life.

If there are areas of your home you’d like to keep off-limits to kids, pets, or aging family members, let motion sensors do the work for you. A well-placed motion sensor can alert you to movement in an off-limits area when you’re not home. When you are home, you can disarm the sensor.