Tips to Avoid Being Spotted by Motion Detectors

an outdoor motion sensored light mounted to the roof
  • Beginner

Motion detectors are systems designed to signal an alarm at any movement that is noticed in the monitored area. Motion detectors are commonly used in everything from automatic doors and customer alert bells in retail stores to home security. There are different types of motion alarm detectors, but there are some universal steps you can take to avoid being spotted by many security systems.

Disclaimer: This advice is meant to inform homeowners of ways their home security system may be at risk. As with all security, caution must be taken to ensure no blind spots are looked over and different ways an intruder may try to circumnavigate your system have been accounted for. Be sure to follow these tips to only test the integrity of your own security system.

Types of Motion Detectors

The most common type of motion detector used in security systems (especially indoors) is a beam detector. These detectors send an infrared beam from one point to another into a light detector. When any object interrupts the path of the infrared beam, it will signal the alarm.

Proximity detectors send out a pulsed signal, usually a high-frequency signal, through the surrounding area and measure how long it takes for the signal to bounce off surrounding objects and come back. If any object enters the area, it will cause the signal to return quicker. This will set off the alarm.

Passive detectors are usually used outdoors and do not send out any type of signal. They instead have special motion light sensors that pick up any infrared light coming from other objects. Everything puts off some level of infrared light, based mainly on the temperature of the object. When an infrared signal is sent to the detector it will trigger whatever alarm is in place.

Don't Rush

outdoor motion sensored light mounted to a brick wall

Always move as slowly as possible in the area of the motion detector. Taking a few slow steps then standing still for periods of time can trick some systems into not recognizing you are there. You should also watch the area where the motion light detector is monitoring. Some models will move to scan a larger area and it may be possible to simply avoid being in the motion detectors path altogether.

Stay Quiet

Another important factor is the noise that you make. Sound will cause the light waves to bend so try to make as little noise as possible. Notice the type of ground you’re walking on and if possible remove your shoes. The slightest noise can cause a motion detector to set off.

Adjust Your Body Temperature

For passive alarm detectors that pick up infrared light your body emits, you can try to adjust your body’s temperature. The detector will look for any change in the infrared it receives from its surroundings but if your temperature matches the room temperature, you may be able to avoid setting off the alarm.

Deflect the Sensors Light

a stack of tempered glass sheets

One last trick you can try is to carry a piece of glass in front of you while approaching the motion detector. When light hits the glass covering your body it will bounce off and return to the sensor. If the light all returns at the same time, the sensor may think it was caused by a wall and not set off the alarm.


The color of clothes you wear makes no difference. In movies people always wear black and while that may help you not be spotted by other people, it makes no difference to the motion detector. Also keep in mind that while the tips provided in this article can help to avoid setting off a motion detector, there is no guaranteed way to do so. Many variables can still set an alarm off despite whatever precautions you take to avoid doing so.