Motion-activated lights can provide an extra layer of protection to your home or business's outdoor security, or add a novel touch to indoor illumination systems. Because they automatically turn off when no one is around, they can also conserve energy and, subsequently, save you money. However; when considering motion-activated lights, one factor to take into account is that motion sensors are often affected by hot and cold temperatures.
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How They Work
The sensors on most motion-activated lights detect moving objects by picking up their radiated heat. Motion activated lights pick up objects such as animals, human and running vehicles particularly well because those objects are generally very warm. Once the object is detected and the light activated, the light stays on for a pre-programmed amount of time, then automatically shuts off when there is no further motion. Most outdoor motion lights also have a built-in photocell, which ensures the sensor only detects heat when it is dark out, and the light stays off during the day.
Of course, many objects radiate heat even when they don't move, such as sleeping humans or pets who are resting within the range of a motion-activated light. The heat sensors in motion-activated lights are, therefore, calibrated to detect significant changes in the field of otherwise unchanging temperature surrounding them. For this reason, motion activated lights become more sensitive in colder temperatures. The colder the temperature field that surrounds them, the easier it is for them to detect heated objects entering that field.
On the flip side, the hotter the temperature field is surrounding a motion activated light, the less sensitive it is to heated objects entering the field. Because the change in temperature between the heated object and the heated field around it is less drastic, the motion-activated light may have a harder time detecting it. If you install and test your motion-activated light on a day when the temperature is 98.6 degrees, you are invisible to it. Fortunately, very few places in the world have nights hot enough to affect the performance of a motion-activated light.
You can expect a sturdy, well-built, outdoor motion-activating lighting system to last up to 15 years. An indoor system should last even longer because it is not susceptible to weather elements. In areas with extreme hot or cold temperatures, or significantly high humidity, the life spans of motion-activated lights can be shortened. The sensors themselves tend to hold up well under such conditions; however, the control station that operates the lights may break down relatively quickly — within five to 10 years. This is because extreme weather, particularly moisture, can damage the relay system connecting the lights to the control box.