Do Motion Sensors Work Through Glass? Getting Best Of Your Motion Sensor 2024

Do Motion Sensors Work Through Glass? Stay with me as I discuss this sensitive topic to ensure your home security is at its best. This article will help you understand more about your motion sensors.

Motion sensors are excellent necessities for your home or business security system. They are electronic devices that detect and measure movements and alert you in several suspicious situations.  

It is recommended to identify the perfect location to install a motion sensor to enhance its effectiveness. You can install the sensors on house corners, in entryways, where valuables are stored, and in master bedrooms, to mention a few. 

Do Motion Sensors Work Through Glass?

Do Motion Sensors Work Through Glass?
Wireless Motion Sensor at Work

No, motion sensors do not work through the glass because modern glass is designed to block or absorb all infrared radiations that come to its surfacePassive Infrared Sensors (PIR) are one of the most famous motion sensors.

It uses light to detect body heat (infrared energy). Almost everything; walls, humans, doors, furniture, and even windows, produce heat. 

Therefore, if you install the motion sensor on the glass, the glass will absorb the heat, thus interfering with the device’s functionality.

Under normal circumstances, the IR energy cannot be detected through the glass. This explains why motion sensors will hardly work through insulated windows.

However, this rule has its exceptions. For instance, there are other non-insulated and older glasses through which infrared energy passes. Such glasses will set off the motion sensor. 

Also, the light penetrating through the glass window may be enough to change IR energy in a small concentrated area. This will confuse the PIR sensor, causing it to activate unnecessarily.

For this reason, you are best advised to install your motion sensors away from windows. Another exceptional situation is using a microwave motion sensor with a dual-technology.

Microwave sensors are uniquely devised to pick up motion through solid objects. They send out microwave signals that bounce from any objects in the targeted vicinity.

However, it’s unlikely that you will find standalone microwave motion sensors as they usually cause too many false alarms.

This is why we have dual-technology sensors in the markets consisting of microwave and PIR sensors. This technology allows the alarm to occur if both technologies are simultaneously triggered.

Takeaway: Most motion sensors use PIR technology to detect movement; this technology cannot work through glass. 

Do Motion Sensor Light Bulbs Work Through Frosted Glass?

Whether the glass is clear or frosted, PIR motion sensor light bulbs will not work through glass. We must figure out how these sensors work to understand why this happens.

Motions sensor light bulbs use PIR technology. Passive Infrared Radiation (PIR) describes a type of radiation containing about 0.7 to 1-millimeter wavelengths.

Therefore, once a human being, animal, or any object approaches the targeted area of the PIR sensor, it will detect the infrared energy. This, in turn, will trigger the lights to turn on.

However, if the object (human or animal) stands behind a glass pane; (whether frosted or clear), the glass will absorb the infrared energy. As a result, the sensor will not pick up any infrared energy and will not set off the lights.

NOTE: Infrared energy is not visible to the human eye.

While humans can’t see this type of energy, they can detect it in heat. This explains why most motion sensor light bulbs contain infrared emitters.

However, a clear or frosted glass barrier will lead to the absorption of all the heat. This will paralyze the sensor’s ability to detect movement beyond the glass as there’s no heat.

Now that we know motion sensors will not work through frosted glasses, some are still intrigued, “does proximity and thickness of glass affect the motion sensor?

If the glass pane is thin enough, it will not absorb all the infrared energy. Also, if the targeted body is close enough to the “thin glass pane,” then it is likely that the IR signal will shine through it.

While a window pane ought to be thick enough to prevent the PIR motion light bulb from functioning, there is still a debate because what happens when you’ve installed the sensor in a glass-protected recess?

No straightforward answer exists because any glass, regardless of its thickness level, can prevent an IR signal from passing through. However, your motion sensor will likely work if you install it against a thin glass layer. 

Even so, we cannot rule out the chances that the molecules in the glass will prevent the wavelength from passing through. Installing a motion sensor light bulb on the glass window is quite unreliable.

Therefore, if you install it directly behind a thin glass-protected area and you are lucky enough to get it working, don’t be too excited, as it’s unlikely to trigger every time there is motion.

Do Ring Motion Sensors Work Through Glass?

All ring doorbells use advanced motion detection to function. They contain built-in PIR sensors that work within a given zone. They work through an integrated camera and passive infrared energy detection.

A ring doorbell could work through a glass in some situations. For instance, it can work through glass if the doorbell doesn’t reflect, absorb, or block the infrared energy.

Most glasses will absorb infrared energy. Because of this, they can impair the ability of a ring doorbell’s motion detection at night.

NOTE: Since most ring doorbells use advanced motion detection, expect them to work through the transparent glass. Therefore, the ring motion sensors will function perfectly during the daytime.

Let’s look at how the ring motion sensors work through glass.

How Does a Ring Doorbell Work Through Glass?

Ring motion sensors contain integrated onboard video cameras that record movements within a targeted zone. 

You can configure the settings of your “targeted zone” settings by expanding and reshaping the coverage to suit your preferences. This video camera will only work flawlessly when the demarcated zone receives sufficient light. 

Therefore, the ring motion sensor will work through the glass during the daytime when it receives its usual view field. However, if the glass is translucent or opaque, it will impair the functioning of the motion glass sensor.

Also, if the glass has a high refractive index or low transmittance, it will tamper with the ring’s PIR sensors’ heat detection ability at night. This is because the video camera can only detect movement if there is sufficient light at night.

If there is no light, ring motion sensors rely on a passive infrared zone. The zone is considerably smaller than the 160° field of view that the camera uses.

The Passive Infrared area is a semicircle, and the PIR sensors are located at the sensors. Therefore, if a glass window or a door panel obstructs the sensors from receiving infrared energy from people in the PIR zone, the ring motion sensor won’t function. It will not detect any presence or movement.

This confirms that a ring motion sensor will partially work at night. Its ability to work is influenced by the glass type, thickness, and quality, among other features.

Takeaway: While all glasses generally block heat sources and impair the functionality of any PIR sensor, the case is different for ring doorbell motion detectors. A ring motion sensor that uses an integrated camera and a sensor will optimally work through the transparent glass. 

However, factors like light availability and surrounding effects like shadows or shades on the camera’s view field will interfere with the ring motion sensor’s performance.

What Can Block a Motion Sensor?

We must agree that motion sensors are critical essentials in any security system. The motion sensor lights are often triggered whenever they detect any movement from humans, animals, or other objects.

Unfortunately, the lights are sometimes triggered by false alarms, which becomes irritating and frustrating. You’ll want to regulate the settings to avoid false triggers if this happens. Therefore, one would want to know possible ways to block the motion sensors.

You can block the motion sensor by the simple art of covering it. However, the type of sensor also influences how well you can cover it.

For instance, PIR sensors are listed among the most popular and the easiest to block. You can also block the microwave motion sensors using aluminum foil. However, if you use ultrasonic or tomographic motion sensors, it will be impossible to block them. 

What Triggers Motion Sensors

To better understand this concept, let’s also have a glimpse of things that trigger a motion sensor, how to adjust the sensitivity, and how best to block it.

Here is a list of things that could set off your motion sensor.


Humans are the most common triggers of motion sensors. The sensors are designed to activate whenever a person approaches them.

Motion sensors don’t use light or a camera. For this reason, a human will trigger it regardless of the time of the day. 


Animals are also common triggers. They could be your pets at home or wild animals wandering around. However, not all animals will trigger the sensor as it depends on their size.

PIR motion sensors (commonly used in outdoor environments) are triggered once they detect infrared heat signals. Therefore, an animal must be warm-blooded to produce the heat needed to trigger the sensor. This feature exempts several insects from activating the alarm.

Since pets may regularly offset false alarms, most motion sensors contain pet-friendly features, the multi-directional ones. This feature only triggers the sensors when a high and low sensor simultaneously detects something. This would mean only an upright human is more likely to trigger the alarm.

Wind-Blown Objects

Some sensors have high sensitivity such that wind-blown objects would easily trigger them. This is also determined by the type of sensor and its location. Sensors installed indoors, and wind-blown objects easily trigger those using microwaves or ultrasonic technologies.

This will especially happen if the windows open, so the wind blows the curtains high into the room. It’ll also happen if an air conditioner scatters a pile of papers.

Passing Cars

If you poorly aim your motion sensor, it will quickly get triggered by vehicles passing by. We always advise against aiming your motion sensor near a road as too many heat-producing vehicles could trigger it.

Also, your motion sensor could be so sensitive that anything minute quickly sets it off. Luckily, you can adjust your device’s settings to avoid unnecessary triggers. Here is how you do it:

Your sensor may contain a toggle or switch location, depending on the brand. You can adjust it manually or use a screwdriver to rotate a slotted dial.

It’s always important to keep and read your manual as it will inform you on the adjustability of your motion sensor and how to do it.

Also, there are some “smart” motion sensors whose apps you can install on your phone or tablet, thanks to technology! They are flexible as you can adjust your settings whenever, wherever. You’d need to check the adjustment option on your app for such sensors.

As we mentioned earlier, motion sensors are available in a variety, with the PIR being the most common. Let’s learn how to block them, depending on the type.

Types of Motion Sensors



A microwave motion sensor has quite an active sensor. It sends microwaves in a demarcated zone, and then identifies those that bounce back. If the microwaves bounce back, they will have identified a movement that will trigger the lights.

Absorbing the microwaves, instead of rebounding them, will help block a microwave sensor. However, the materials you can use to block are limited as microwaves can pass through many solids.

Aluminum foil will work excellently in blocking a microwave sensor. It will absorb the microwaves and prevent the lights from activating. Wrap the sensor in a foil, and voila!


Tomographic sensors are designed to establish a field of radio waves within a room. Therefore, the sensor is triggered if anything interferes with the radio waves.

Due to this nature, blocking a tomographic sensor is impossible.

Try using an aluminum foil to reflect the radio waves. While this may confuse the sensor, it could also trigger.


Ultrasonic sensors are uniquely built compared to other types of sensors. They depend on the emitter and receiver to function.

To trigger the sensor, the emitter and receive ultrasonic waves between each other. Therefore, blocking the ultrasonic ones is also impossible, like the tomographic sensor. Attempting to do it will lead to the triggering of the sensor.

The only way to block such a sensor is by maintaining the signal between the emitter and the sensor. However, this is a pipe dream.

The trick here is to install a master switch that would ease the turning on and off of the sensor.

Let’s now learn how to block the most commonly used sensor, the PIR.

PIR sensor functions by detecting infrared signals from heat. Therefore, it makes sense that you will need to trick the sensor into imagining there’s no temperature change to block the PIR sensor.

Most people prefer black electrical tape as it is thick enough to prevent heat from penetrating. Applying it is also a piece of cake! You can block it using any insulating material. 

We’ve also mentioned glass severally in this article. Most motion sensors that use the PIR technology can hardly work through glass. Glass will absorb the heat. Therefore, block a PIR sensor by placing it behind glass.

Takeaway: Everyone has a couple of reasons for blocking their motion sensors, be it house renovation or your away-from-home vacation. Blocking a microwave and ultrasonic sensor may prove futile. Block a microwave sensor using aluminum foil and a PIR sensor using black tape of a glass.

What Can Interfere with Motion Sensors?

We recommend maintaining your motion sensor for excellent effectiveness. 

Like any other device, after prolonged use, dust and debris will accumulate on the screen of your motion sensor. These elements will interfere with the infrared energy, rendering your sensor less effective. The solution is to clean it at least once every several months. Use a dry or slightly damp microfiber cloth to clean it.

Also, consider blocking the sensor when renovating your house to prevent elements like paint from getting to the device. If paint enters the sensor, you must replace the system.

Other material that could block and interfere with a motion sensor includes the following:


Styrofoam is one of the best insulators available in the market. It can interfere with a motion sensor by inhibiting heat.

Aluminum Foil

Aluminum foil is also an effective material that can interfere with the functioning of your motion sensor. Its unique conduction properties enable it to block radio and electromagnetic waves entirely. Using it to cover your sensor’s lens will reduce its sensitivity and consequently block its vision.

Strong Magnetic Field

A strong magnetic field will help your doors and window sensors function as they use magnetic strips. The door and the frame are conjoined with a strip, forming a circuit. If you break this circuit, then the sensor will be triggered.

This is a vulnerable motion-sensing technology, as you can easily manipulate it. For instance, introducing a stronger magnetic field will interfere with the sensor’s functioning. 

Pointing Infrared Lights at Lens

As wrong as it sounds, pointing at a stable beam of an infrared wave will interfere with your sensor, thereby resetting it. For this to happen, keep pointing the light in the direction of the lens till it becomes dysfunctional. 

NOTE: This will not work for all motion sensors. For some, pointing the infrared radiation will trigger rather than interfere with the alarm.

Electrical Tapes

Black electrical Tapes have severally proven to be effective in interfering with a motion sensor’s function. Place the tape from the edge and cover the sensor completely. You will have blocked it, thus preventing it from functioning normally.


Cardboard pieces also interfere with the functioning of a motion sensor by limiting its field view. To do this, raise cardboard against the camera’s lens and block its sight.

If the board is not sufficiently thick or if the sensor can view through it, you will not have blocked it effectively.

Summarily, several elements can interfere with your motion sensors. Dust and debris are the most common and natural elements.

However, cardboard, black tape, aluminum foil, and Styrofoam are some of the artificial elements you can use to interfere with your motion sensor intentionally.

Where Should I Place the Motion Sensor?

Choosing the location of a motion sensor is crucial as it determines how well-protected you are from insecure situations. Discussed below are some of the most effective places to place a motion sensor:

Corner Spaces

The corner space is excellent as it provides your motion sensor with an extensive view. It will help to install a motion sensor in the corner of each room, aimed at the doorway. This way, anyone entering the room will likely set off the alarm.

Near Valuables

Burglars will break into your house, looking for valuables like expensive jewelry. This is why you should place your motion sensors directly or behind the most valuable items. If anyone moves close to them, you’ll be informed right on time.

Outside Patios

Installing motion sensors on the patio outside your home is a wise idea—prowlers like to sneak into the back doors. The sensors will immediately inform you once they detect the Prowler’s movement close to the backdoor.

Second Floor Bedrooms

While burglars will most likely enter your house in the first-floor entryways, installing motion sensors on the second-floor bedrooms is also safe.

Others imagine they’ll be sleek enough not to get caught sneaking through the second-floor bedrooms or windows. The motion sensor will alert you if anyone approaches this area when you least expect it.


Basements are also common entry locations for burglars, so it will help to install several sensors here. If the basement contains lots of clutter, place them where it won’t be blocked. 

Also, install the motion sensor near the staircase leading upstairs.


Contrary to popular opinion, motion sensors can work at any angle. Some intruders will want to manipulate the sensors if they enter the house, knowing where they are located.

If you install it on the ceiling, it’s unlikely that they’ll suspect it. This is a suitable location to prevent a thief from avoiding the detectors.

Within Decorations

Integrating motion sensors Inyo your household decors is also a worthwhile idea. You can hide them within your photos and knickknack so intruders won’t easily spot them.

We now know the best places to install our motion sensors. The following are the least effective places to install them:

Near Windows

Installing your motion sensors near windows is not the best idea, as it may result in frequent false alarms. The windows usually receive direct sunlight, which can confuse heat-activated sensors.

It is also a wrong idea since it will help effectively work if the burglar walks parallel to them instead of straight ahead.

Near Heat Sources

You also don’t want to install your motion sensor near a heat source, as it can create false alarms. Consider installing the motion sensors away from air vents and radiators, as any change in heat could unnecessarily trigger the alarm.

How Can I Make Motion Sensors Work Through Glass?

As we mentioned earlier, motion sensors can hardly work through the glass as most of them use passive infrared technology to detect movement. Insulated glasses, in particular, are designed to absorb heat. If this happens, the PIR sensor will not detect any heat.

However, you can make your motion sensor work through glass using a different motion sensor technology and a non-insulated window type.

Older plates and non-insulated glass will allow a considerable amount of infrared energy to penetrate. This energy will be enough to trigger the motion sensor. Also, if the light penetrating the window is concentrated in a given area, it will provide enough temperature change to trigger the alarm.

Also, use a microwave motion sensor with dual technology if you want it to work through glass. This is because a microwave sensor has properties that enable it to detect motion through solid objects. Therefore, you are advised to adjust the microwave compaction of the sensor during installation for the best effectivity. 

A radar motion sensor bulb is also an excellent choice if you want it to work through glass. Such bulbs contain photocell sensors that detect infrared and visible light.

Even though glass absorbs heat, it also allows light to pass through; thus, a radar motion sensor bulb will detect this light and trigger the alarm.

Which Type of Proximity Sensor Is Not Used to Detect Glass Objects?

A proximity sensor is a non-contact sensor that detects the presence of an object soon as it approaches the sensor’s field.

A variety of proximity sensors, sound, light, infrared radiation, or electromagnetic fields can be used to detect a target (object/human).

You can use these proximity sensors in phones, recycling plants, self-driving cars, anti-aircraft systems, and assembly lines.

The inductive and capacitive proximity sensors are the most used.

Inductive Proximity Sensor

Since an inductive proximity sensor uses an electromagnetic field, it is specially designed to identify metal objects only.

Once the metal target is within the electromagnetic vicinity, the inductive characteristics of the metal will tamper with the electromagnetic field’s properties. 

For this reason, an inductive proximity sensor can only detect metallic objects. The inductive nature of the metal object will determine whether it will be detected at a greater or shorter distance.

In summary, an inductive proximity sensor cannot be used to detect glass objects.

The following are other types of proximity sensors that CAN BE used to detect glass objects:

Capacitive Proximity Sensor

Unlike inductive proximity sensors, which are limited to detecting metallic objects, capacitive ones are not.

They can detect anything that can conduct an electrical charge; this could be glass, plastic, water, wood, metals, name them! It is no surprise that it is primarily used in liquid-level detection.

Therefore, capacitive proximity sensors can be used to detect glass.

Photoelectric Type Sensors

They are available in two main types; reflective and through-beam photoelectric sensors.

The reflective proximity sensors consist of a photoelectric receiver. They detect objects once the sensor emits light and reflects it at the photoelectric receiver. 

The through-beam sensors are designed to detect objects when they break the beam of light between the emitter in the sensor and the receiver.

This proximity sensor measures the distance and a target’s presence through a light transmitter. This light transmitter is always infrared and has a photoelectric receiver. 

Through-beam sensors are popular in industrial manufacturing. 

Due to their nature, photoelectric sensors can be used to detect glass objects.

Ultrasonic Type Sensor

This type of proximity sensor measures the distance of a “targeted object.” It does this through the emission of ultrasonic sound waves that are converted into an electrical signal when reflected.

These sound waves often travel faster than an audible sound’s speed. An audible sound is that which the human senses can detect.

Like photoelectric, ultrasonic sensors also consists of the transmitter that produces the sound using piezoelectric crystals and the receiver. The receiver receives the sound once it has traveled from the target.

Ultrasonic sensors can be used in automobile self-parking technology and anti-collision safety systems. They are also handy in robotic obstacle detection systems and manufacturing technology. 

This type of sensor can be used to detect glass bottles.

Reminder: The inductive proximity sensor is the only one that cannot detect glass objects because it is specially designed to detect metallic objects only.

Pros and Cons of Wired and Wireless Motion Detectors?

There is something for everyone! Technological advancements have made even the unimaginable things possible! There are various motion detectors in the market, from the PIR motion sensors, the microwave sensors, the ultrasonic, photoelectric, wired, and wireless.

With all these detectors, one is bound to be torn on which brand to choose. We can narrow down and classify all motion detectors into two primary categories: wired and wireless. We will discuss the advantages and disadvantages to help you decide which type best suits your needs.

Wired Motion Sensors

The name “wired” describes the functioning mechanism of these types of sensors. They are “wired” or integrated into your building’s electrical system. Therefore, these devices are powered by your home’s electrical wiring.

Once a wired Motion sensor detects motion, it will signify the ethernet cable or the phone line in your home to the security camera. The camera will respond by recording the happenings in the targeted area.

Advantages of Wired Motion Sensors 


They Are Reliable

There are limited to zero chances that the signals that travel within a wired system in your home will get lost. For this reason, you can fully count on a wired Motion sensor to provide security and alert you in case of any suspicious activity. 

They Are Secure

Unlike most modern technologies that use wireless and susceptible connections, wired sensors do not. This is advantageous because such a system leaves no room for hacking by cyber criminals as they don’t depend on a wireless internet connection. This will give you vital peace of mind as you are sure you are well-protected, with no one manipulating or “hacking” into your systems.


Sometimes life can get so busy that you’d barely think about replacing the batteries in your security device. This is usually the least of your concerns when using a wired Motion sensor system. It uses your home’s connectivity as a power source, so you’ll never need to worry about replacing the batteries.

Disadvantages of Wired Motion Sensors


They Are Difficult to Install

We’ve mentioned that a wired sensor relies on your home’s electrical connectivity as its power source. For this reason, installing them correctly can be an uphill task. We recommend hiring a licensed electrician to ensure the job is perfectly done.

Some Require Outlets

If you are using plug-in sensors, you are also tasked with locating them near an outlet for the best effectiveness. For instance, installing them in a garden or at the far end of the garden might be challenging as it’s unlikely to have a plug outlet here. In such a case, you only have limited options on where to place them. 

Poor Mobility/ Inconvenience

Since a long-wired Motion sensor is integrated into your home’s electrical system, moving them elsewhere is quite challenging. This would mean disconnecting and reinstalling them in your new home, which can be costly and time-consuming. 

Wireless Motion Sensors

The name “wireless” literally describes its mechanism. It uses an internet or cellular network to signal your home’s security system.

 Unlike the “wired” sensors connected to your home’s electrical system, the wireless ones are not.

Wireless sensors do not use electricity as batteries generally power them.

Advantages of Wireless Motion Sensors

They Are Easy to Install

Unlike wired sensors with a complex installation process, wireless ones are easier to install. They do not need to integrate into your home’s electrical system so you can do it as a DIY project.

They Are Convenient

Technological innovations are meant to make life more manageable and comfortable, which is what wireless sensors do! Imagine operating your home security system in the comfort of your phone, at home, at work, or when away on vacation! Smart wireless

Motion sensors also come with mobile apps. These security devices will notify you through your smartphone when you’re away. The ability to remotely monitor and control the wireless security system gives them an upper hand over others in the market!

They Are Mobile

Wireless Motion sensors are more portable than wired ones. All you have to do is pick them up and tag them along to anywhere you are moving! While the wired sensors will require you to disconnect and reinstall them in the home’s system when you move, this is not the case for the wireless. 

Let’s now look at the flip side of the coin! The followings are the Cons/ disadvantages associated with wireless Motion sensors.

Disadvantages of Wireless Motion Sensors


They Are Susceptible to Hackers

This is one of the most notable shortcomings of wireless Motion sensors. Since they use the internet connected by WIFI or cellular network, they are more prone to being hacked by cybercriminals. Therefore, protect your security system from such an eventuality by using solid or uncrackable passwords.


While wired sensors have limited chances of losing signals, wireless ones are the opposite! The signals sent through the internet can get lost because of connectivity or other human-manipulated issues.

Wireless Motion sensors Use Batteries

This means that when the batteries get depleted, and you are unaware, you’ll be exposed to danger. One must periodically change the batteries for optimal protection to prevent this from happening. However, one can also forget! Your device will no longer be able to detect suspicious movements. And this is quite a disadvantage.

Final Thoughts

When you install your motion sensor into your home’s security system, you want to ensure that it works as efficiently as possible. This will give you peace of mind knowing that you and your family are protected in case of an eventuality. This article has discussed the question…

Do Motion Sensors Work Through Glass?

Since most motion sensors use PIR technology, they will hardly work through glass. This is because glass absorbs heat, so the sensor will not identify any infrared energy.

However, you can make your sensor work through glass by using old or non-insulated glass. You can also use a microwave sensor.

Have we covered everything you need about motion sensors and their association with glass? Let us know your thoughts! What type of sensor do you find most effective on glass?

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