If you can install a conventional outdoor light fixture, you can install a motion sensor light, although aiming and adjusting it takes extra effort.
Time Two to eight hours
ComplexityIntermediate
Cost$50 - $200
Introduction
An important reason to install motion sensor lights in the city is to deter human intruders, but up here in California's coastal mountains, we're more concerned about the four-footed kind, and the lights really do help keep them away. We have regularly been plagued by hungry visitors that include bobcats, foxes, raccoons and deer. I even came face-to-face with a mountain lion, but thankfully I was close enough to the door to my house to avoid actual contact. That encounter, along with the loss of prized plants and a few house cats, prompted us to deploy motion lights, and things have been more or less quiet ever since.
Most motion lights contain passive infrared (PR) sensors that detect heat emitted by living bodies, but some of them use microwave (MW) sensors that detect reflections of the pulses they continually send out. In the city, PR sensors are more common, because they aren't triggered by electrical background noise and are less prone to nuisance trips. People in rural areas may prefer MW sensors, particularly if they want to detect small, raccoon-sized intruders. Dual sensor models incorporate both types of sensors.
Installing motion sensor lights isn't much different than installing conventional light fixtures, but you have to place and aim them correctly if you want them to be useful. Electricians Ryan Gregor and Ben Kolo both have years of experience installing residential and commercial motion sensor lights, and they have some helpful tips to keep you on the right track.
Tools Required
- Drill
- ladder
- Non-contact voltage tester
- Pliers
- Screwdriver
- wire stripper
Materials Required
- Electric box
- Electrical cable
- Electrical tape
- Motion sensor light fixture
- Silicone caulk
- Wire connectors
Project step-by-step (8)
Step 1
Choose a location
You can install motion sensor lights anywhere, but if you want them to provide security and not simply illuminate your path in the dark, place them high enough to be able to survey the area and point them away from sources of nuisance trips, such as doors and windows.
“To function effectively as part of a security system, motion sensor lights must be installed at the correct height and in the right location. Generally, they should be mounted at least seven feet from the ground level, allowing them to cover a larger area and detect movement more accurately,” advises Gregor. They can go as high as 10 feet, according to Kolo.
- Pro tip: If there’s no electrical wiring at your planned point of installation and you don’t want to install any, wireless solar-powered options are available. They usually come with detachable panels that can be installed in a sunny location some distance away from the actual light.
Step 2
Run wires and install an electrical box
A motion sensor light is almost identical to a conventional light fixture in terms of wiring, but because it has its own switch, it shouldn’t be controlled by another switch in the house. If you’re replacing a conventional switched outdoor light fixture, you can either bypass the switch for that fixture by removing the switch and connecting the black wires attached to it, or you can leave the switch in the ON position.
When you aren’t replacing an existing fixture, new wiring can come from any lighting or receptacle circuit in the house or directly from the panel. Kolo cautions that all electrical work needs to be done according to building code requirements, that you must use weatherproof electrical boxes and covers and that you must ensure the system is grounded.
- Pro tip: The recommended wire gauge for a 15-amp light circuit is 14 AWG, but if you’re branching off a circuit with 12-gauge wire, use 12 AWG wire instead.
Step 3
Turn off the power
This is Rule Number One of electrical wiring. If you’re replacing an existing light fixture, don’t rely on the switch to turn off the power. Someone could turn on the switch while you’re working. Instead, turn off the breaker that controls the circuit the light is on. In the next step, you’ll use a voltage tester to double-check that the power is off before wiring.
Step 4
Wire the new fixture
If you’re replacing an existing light fixture, unscrew the fixture from the electrical box and pull it away far enough to access the wires. Probe the wires with a non-contact voltage tester. If the tester beeps or lights up, the power is still on, so go back to the breaker box and turn off the correct breaker. Once you’ve done that, you can disconnect the wires and remove the fixture.
To wire the motion sensor light, first identify the hot (black), neutral (white) and ground (bare or green) wires in the circuit wire and in the fixture. Twist the hot wires together clockwise, using pliers, then twist the white and bare or green ones together in the same way. Screw a wire connector onto each wire pair.
- Pro tip: Most outdoor fixtures have a rubber gasket to seal the fixture to the electrical box and keep out moisture. You have to pass the wires through this gasket before you connect them.
Step 5
Mount the fixture
Every fixture is a little different, but most come with a crossbar that screws to the electrical box and has holes for the screws that hold the fixture.
- Screw the crossbar to the fixture.
- Push all the wires into the electrical box, then set the fixture in place with the gasket set firmly against the mounting surface.
- Screw the fixture to the crossbar using the screws provided.
Pro tip: If you’re mounting the fixture on a rough surface like stucco or brick, apply a bead of silicone caulk around the perimeter of the gasket to keep water out.
Step 6
Aim the motion sensor and lights
The sensor is the dome-shaped or rectangular box on the bottom of the fixture. On most models, it rotates independently of the light bulbs. Aim it at the center of the “walk zone,” which is the area you want to protect, and point it slightly downward.
“You’re aiming for movement across that zone,” says Gregor. “Imagine someone walking by – the sensor should pick them up throughout their approach. For example, on a long driveway, position the light halfway down, not right at the garage.”
Regarding the lights, Kolo advises: “Avoid light obstruction by aiming lights away from windows and doors. This will cut down on glare while illuminating the intended area.”
- Pro tip: Keep the bulbs as far away from the sensor as possible. The heat from the bulbs can trigger the sensor and turn on the lights when there’s no one there.
Step 7
Adjust the controls
Underneath the sensor or on one side, you’ll find two controls. One adjusts the sensor’s range, and the other adjusts the lights’ on-time.
- Set the on-time to your preference. The lights can stay on for one, five or twenty minutes after the sensor trips. On some models, they can turn off after just a few seconds.
- Adjust the range to its maximum, then turn on the power (if you haven’t done that already) and have someone enter the walk zone from far away. If the lights come on when the person is too far away, reduce the range setting until the far limit of the walk zone is where you want it.
Step 8
Limit the field of view, if necessary
Most motion sensors have a lateral view of 180 degrees, which means someone can turn on the lights even when they aren’t standing in front of the sensor. If you don’t find this useful and want to limit the field of view more than the adjustments allow, cover the edges of the sensor with plastic tape.
About the Experts
- Ryan Gregor has over a decade of experience in the electrical field. He is the founder of RCG Electrical in Adelaide, Australia.
- Ben Kolo worked for many years as an electrician before he became the franchise owner of Mr. Electric, a Neighborly company in Central Iowa.
Originally Published: May 15, 2019
