If you have seen the movie Predator, then you may remember the scene where Dutch (played by Arnold Schwarzenegger) avoids getting captured and killed by the Predator when he accidentally covers himself in mud, which hides the heat from his body. The Predator, using body heat signatures to identify its prey, can't detect Dutch even though looking right at him -- the mud hides his body's heat signature. Well, I haven't tested it (yet?), but the same concepts should apply when trying to avoid detection by a motion sensor light! (if you test this, let me know and I'll post the results!)

In previous articles I have discussed how motion sensor lights work, and how the heat from objects moving across the motion sensing field will trigger a motion sensing light. This article is not meant to give you ideas for sneaking past someone's motion sensor, but instead is to help you better understand how your lights work and possibly help you better place your motion lights to pick up the type of motion you want to trigger your lights. I will plan to set up some testing in my backyard (using my kids - they will love it!) to see how well we can avoid our motion sensing lights--I'll post any results. Here are some suggestions and ideas on avoiding motion sensors (note that these apply to heat-sensing motion detectors like those typically found in motion lights - these do not necessarily apply to sound, beam or other detectors):

Dusk to Dawn Feature

Many times we are asked about the meaning of the "Dusk to Dawn" feature of motion lights.  This is a very nice feature that you will find on most motion sensor lights, so understanding this will help you make the best choice when choosing the light that is right for you. In short, the dusk-to-dawn feature of a light will cause your motion light to only activate when it is dark.  In daylight hours when existing and ambient light is present, the light will not activiate when motion is detected.  This feature uses a small photocell like the one pictured above to detect the presence of available and existing light.  If light is detected, the motion light will not trigger.  If light is not detected, then the light will turn on when motion is detected.

Motion detectors sense moving objects by picking up the heat that radiates from the object.  The motion light will automatically turn on when the motion detector senses an object moving within its detection range -- the sensor will work especially well when warm objects move within the detection area, such as animals, people and cars.

Once motion is detected and the light turns on, the light will remain on for a set period of time.  Most outdoor motion lights will allow you to set the amount of time that the light will remain on, typically anywhere from 1 minute to 25 minutes.  Then, if the detector no longer senses movement after the set time, the light will automatically turn off.  In addition, most outdoor motion lights include a photocell that will deactivate the light during daylight.  As a result, the light will only turn on when motion is detected during darkness.

You will see many motion detector lights with a feature called "Dual Brite" or "Dual Brite Timer". What is the Dual Brite feature? It is a very convenient and valuable feature that adds a new level of function to a motion light. Below, I'll describe how the Dual Brite feature works.

The Dual Brite feature adds another set of light control settings to a motion light.  When the Dual Brite setting is on, the light will automatically turn on in a half-bright mode for a set period of time after dusk.  So when it gets dark, the light automatically switches on in dim mode, providing you with convenient lighting during times when it gets dark early in the evening, and the security of automatic dusk lighting.  The Dual Brite setting does not interfere with normal motion light settings--if the motion detector picks up motion, the light will switch on in full power mode, even if the light is already on in dim mode from the Dual Brite setting.