Guide to Motion Sensors

Safety Team
Updated Feb 26, 2021
5 min read

Motion detectors are a key part of building a robust home security system. Motion sensor alarms can provide instant alerts to keep you aware of any potential dangers and even act as deterrents for would-be burglars. In many cases, they can prevent a crime from taking place. In order to make the best use of your motion sensors, though, it helps to know more about how they work and how to install them effectively.

What Are Motion Sensors Used For?

Motion sensors are primarily used in home security. A motion detector will trigger if it senses body heat or movement on your property, which is a great way to keep burglars away before they can commit a crime. 

Besides home security, motion detectors also have plenty of other uses. Motion sensors can react to a variety of situations, like if pets or children enter a room where they aren't supposed to be. A motion sensor can also trigger a doorbell as soon as someone approaches the front door or it can be used to trigger a light for the same reason. When paired with lighting, motion sensors can also be used to switch lights on when someone enters a room. This can save on energy costs as lights will automatically shut off if the sensor does not detect any movement. 

What Are the Different Types of Motion Sensors?

There are several different types of motion sensors that use different types of technology. The most commonly used types are:

  • Passive infrared (PIR) sensors: This is the most common type of motion detector sensor, and it's designed to detect body heat and movement.
  • Microwave motion sensors: This technology uses microwave pulses, which provides more coverage but is usually more expensive.
  • Ultrasonic motion sensors: This type of sensor emits ultrasonic waves that pick up on movement by detecting wave reflection. 
  • Dual-technology motion sensors: Rather than using one type of technology, this type of sensor combines multiple. For example, a sensor could combine both PIR and microwave technology to increase effectiveness. 

How Do Motion Sensors Work?

When asking the question “How do sensors work?” it’s important to know about the different types first. Motion sensors typically work with a passive infrared sensor, which works by sending out rays to detect heat. These rays will fan out from the sensor so it’s more sensitive the closer something is to it. However, these rays won’t be able to penetrate through walls or furniture, which means they need to be placed somewhere without obstacles. 

PIR is the most common technology used for motion sensors but there are several other types. Ultrasonic sensors, vibration sensors, area reflective and microwave sensors are some of the less commonly used types, and each uses a different type of sensor to detect movement. Sometimes a sensor will combine two technologies which can either boost range or reduce the number of false alarms. 

Are Motion Sensors Effective?

The effectiveness of a motion sensor will depend on a few different things. Factors such as the technology used and the placement of the motion sensor will determine how successful it is. Provided a motion sensor is placed in a strategic place, it can pick up potential threats fairly easily. 

While they are highly effective on their own, you will need to install them in places without any obstacles and check the batteries regularly. For a more well-rounded approach to home security, you could pair motion sensors with motion-activated lights, cameras or alarms to work as an effective deterrent to stop any burglar in their tracks. To go one step further, you could even opt for professional security monitoring. 

Can Motion Sensors Help Prevent Burglaries?

Motion sensors, when strategically placed, can act as both a deterrent and an alert for burglary attempts. Placing a motion sensor above windows and doors is a great way to keep your home safe because you will either get an alert or an alarm will sound if the sensors detect any movement. If attached to an automated light that comes on when it senses movement, this can act as a simple yet powerful deterrent for potential intruders. 

Where Should I Place Motion Sensors?

Where you place your motion sensors is very important to get the most out of them. Ideally, you want to install a motion sensor in a strategic place that covers a wide area — saving you from having to get lots of sensors.

  • High up: Placing your motion sensor in a high place will give the sensor a birds-eye view of the space. It’s recommended that 6 to 8 feet is a good height because it will cover enough space without being so high it leads to blind spots.
  • Over a doorway: Intruders will often approach a doorway, so putting a motion sensor just above it is a perfect spot to catch a potential burglar in the act.
  • High-traffic areas: If an intruder were to enter your home, they would most likely have to walk through the same high-traffic areas that you and your family do. Putting a motion sensor in a high-traffic area such as a hallway or porch will no doubt catch any intruders and alert you quickly. 
  • In the corner of a room: Placing a motion sensor in the corner of a room will likely give it the widest possible view of the room.
  • Windows: If an intruder can’t get through a door, their next step will be to gain access through a window, which makes them a great spot to place motion sensors. 

If you are unsure about where to place motion sensors, it might be worth enlisting the help of a home security company that offers professional installation. This method also gives you the option of signing up for professional monitoring services for added protection for your home. 


Motion sensors can be a crucial part of keeping your home safe from intruders or burglars. They can be used both inside and outside the home and pair well with many other types of security equipment including cameras, security lights and burglar alarms. 

When comparing motion detectors, look for the technology used, whether they come with cameras or floodlights, how they are powered, whether they can be customized to avoid pets and how easy they are to install.

Home Security Experts

Safety Team

The Safety Team is a group of experts that handle provider research, product reviews and recalls to make your home safety and security search as easy as 1-2-3.

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