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About This Project
Why come home at night to a dark door? Or try to walk an icy sidewalk you can’t see? And what about those occasional strange noises you hear outside in the middle of the night?
Outdoor lights that are automatically activated by motion detectors can solve all these problems—and others. They’ll automatically come on to light up the kids who cut through the yard or the intruder on the deck, and they’ll even expose the furry critter that’s been raiding your garbage can.
In most cases, motion detector lights are easy to install if you’re simply replacing an existing outside light fixture. And they won’t cost you a fortune: Prices range from about $25 for a basic two-bulb floodlight—like the one we show in our photos—to about $60 for a decent-quality front door light.
In this article, we’ll tell you how motion detector lights work, show you the best places to put them, and walk you through a safe and trouble-free installation.
How Motion Detectors WorkMotion detectors are small electronic eyes that detect infrared waves—heat waves that radiate from moving objects. When the detector senses an object moving across its field of view—especially warmer objects such as people, animals and cars—it electronically turns on the lights. The light stays on anywhere from 1 to 20 minutes, depending on how you preset the timer. Then the detector automatically shuts the light off unless it continues to sense movement. A photocell deactivates the light during daylight hours.
Most motion detectors have a semicircular field of view of up to 240 degrees and a distance range, adjustable on most detectors, that extends to 70 ft. or more. The detector will react to the movement of your dog, an approaching person, a passing car or sometimes even wind-blown leaves.
Nuisance “trips,” such as blowing leaves or a passing car, can fool the detector and turn the lights on when you don’t want them. These can be annoying to both you and your neighbors, and in fact, some homeowners won’t install motion detector lights for this reason.
However, you can solve most unwanted switching-on by adjusting the distance-range setting and by carefully aiming the sensor to limit its field of view. You can also narrow the field of view even more by applying tape to the sensor. If nuisance trips concern you, be sure to buy a light that has an adjustable distance-range setting, and an aimable detector unit.
Motion detectors allow you to operate the light in the conventional, manual way, usually by flipping the switch off for a second, then back on. This allows you to keep the light on at night when you want to, even when there’s no motion. By double-flipping a second time, you return to automatic.
Where to Put Them
For best effectiveness, position motion detector sensors
to cover the walks leading to your front and back doors and the driveway. That way the lights will come on when you come home at
night. You can also use them to light up decks, patios and any potentially
hazardous locations such as around stairways and swimming
pools.
If improved security is a priority, position the lights to cover all the approaches to your house, including fence gates, the patio door, the darker areas of your yard, and around trees and bushes. Good lighting can’t guarantee security, of course, but it’s one of the best low-cost ways to get unwanted intruders to back away.
Ideally, it’s best to mount motion detector lights 6 to 10 ft. above the ground and position them so that most movement will occur across the sensitivity zone rather than directly toward the detector.
Obviously you can’t always do that if you use existing light locations. One solution is to buy a remote motion sensor unit that you can mount some distance away from the light itself. Remote sensors cost $15 to $25. The wires connecting them to the light are low-voltage and not dangerous, so you don’t have to enclose them in metal or plastic conduit.
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