Can I add a motion sensor to an existing light?

Quick Answer

Yes, you can add a motion sensor to an existing light fixture to enable motion-activated lighting. This can be a relatively simple do-it-yourself project that doesn’t require completely rewiring the light. You’ll just need to get a compatible motion sensor, disconnect the light from power, connect the motion sensor to the light wiring, mount the sensor, and restore power. Make sure to follow all electrical safety precautions when working with wiring.

Steps to Add a Motion Sensor

Here are the basic steps to add a motion sensor to an existing hardwired light:

1. Turn off power to the light at the circuit breaker. Verify power is off with a non-contact voltage tester.
2. Remove the light fixture cover and bulbs to access the wiring.
3. Disconnect the power wires from the light fixture.
4. Connect the light’s power wires to the matching wires on the motion sensor using wire nuts.
5. Mount and position the motion sensor according to the manufacturer’s guidelines.
6. Turn power back on at the circuit breaker.
7. Test that the motion sensor successfully activates the light.
8. Make any needed adjustments to the motion sensor activation range and time settings.

See the detailed step-by-step instructions below for more in-depth guidance on how to connect a motion sensor to an existing 120V hardwired light fixture.

Choosing a Motion Sensor

When selecting a motion sensor for an existing hardwired light, you’ll want one that’s compatible with the light fixture and easiest to wire into the existing electrical system. Consider the following:

• Power source – Choose a 120V AC wired motion sensor that can simply tie into your existing light wiring. Battery powered or low voltage motion lights require fully separate wiring.
• Wiring compatibility – Select a motion sensor made to wire directly to an existing light fixture without rewiring the entire circuit. Look for quick wire nuts or push-in wiring.
• Lighting load – Match the motion sensor’s rated wattage or amperage capacity to the wattage of your light fixture. This info should be printed on the light and motion sensor.
• Detection features – Decide if you need dual motion & ambient light sensors, adjustable motion sensitivity, detection ranges up to 30 ft, etc. The more detection options, the more flexibility you’ll have in adjustment.
• Housing – Choose an internal sensor Housing box that can easily mount directly on top of your existing exterior light fixture.

Indoor and outdoor motion sensors are available. Be sure to use an exterior motion sensor outside that is weatherproof and designed for outdoor use according to its IP rating.

Wiring a Motion Sensor to an Existing Light

Follow these step-by-step instructions to connect a motion sensor to an existing 120V wired light fixture. This guides you through installing a generic indoor motion sensor, but a similar process applies to wiring most 120V AC motion sensors to existing lights.

Turn Off Power and Access Wires

Start by turning off power to the light fixture at the main circuit breaker panel, in order to safely work on the wiring.

1. Locate the circuit breaker controlling the light fixture and switch it to the OFF position.
2. Verify power is off by testing the light switch and wires with a non-contact voltage tester. The tester should NOT detect voltage.
3. Remove the cover plate from the light switch if applicable.
4. Take the cover off the light fixture to access the internal wires. This usually involves unscrewing a couple screws.
5. Remove the light bulb(s) from the fixture.

The wiring connecting to the light fixture will usually consist of 2 or 3 wires:

• Hot or live wire – Black insulated wire that carries current from the circuit breaker panel.
• Neutral wire – White insulated wire that completes the circuit back to the panel.
• Ground wire – Bare copper or green insulated wire that grounds the fixture.

There may also be a grounding screw or a wire from the light fixture chassis connected to ground.

Now the light’s wiring is accessible to install the motion sensor.

Install and Connect Motion Sensor

With the power off and wires exposed, you can connect the motion sensor to the light fixture.

1. Separate the sensor module from the mounting plate if required.
2. Connect the motion sensor wires to the light fixture wires with wire nuts:
   • Sensor hot/live to light hot
   • Sensor neutral to light neutral
   • Sensor ground to light ground
3. Attach the motion sensor module to the mounting plate.
4. Secure the motion sensor mounting plate to the electrical box or light fixture.

The motion sensor switch provides a bridging connection between the incoming hot wire and the light fixture hot wire, allowing the motion sensor to control power to the light.

The neutral and ground provide completed circuits to safely operate the light and motion sensor.

Restore Power and Test Operation

With the motion sensor completely installed and wired, turn power back on to test it.

1. Turn on the circuit breaker to restore power to the light and motion sensor.
2. Turn on the light switch if there is one.
3. Walk in front of the motion sensor and verify the light turns on automatically.
4. Adjust the motion sensor activation range, duration settings, and light level (for dusk-to-dawn sensors) as needed.

The motion sensor should now successfully control the existing light automatically based on occupancy and ambient light levels. Enjoy your new hands-free, energy-saving motion activated light!

Exterior Lights and Motion Sensors

For exterior lighting around a home, motion sensors are extremely popular to provide hands-free exterior lighting for safety, security, and convenience. Motion activated security lights or flood lights are a great example.

To add motion activation to your existing outdoor lights, the process is very similar as wiring an indoor motion sensor. There are just a few additional things to keep in mind:

• Make sure you purchase an exterior-rated motion sensor that can withstand the elements. Verify it has an IP65 or higher ingress protection rating.
• Most exterior motion sensors are LED compatible only, so verify LED compatibility if you have LED security lights or flood lights.
• Look for a motion sensor with multiple detection options – motion, temperature, adjustments – to avoid false triggering.
• Consider a motion sensor with a photocell to automatically activate from dusk to dawn for added convenience.
• Make sure the motion sensor is rated for the wattage of your exterior lights.

The wiring process is the same, just be sure to use silicone-filled wire nuts for reliable, waterproof connections when wiring exterior lights and motion sensors.

Smart Light Switches with Motion Sensors

If you’re interested in fully automating and controlling your lights via your smartphone, another option is a smart light switch with built-in motion and ambient light detection.

Smart light switches replace your standard in-wall light switches to offer app control, scheduling, motion sensing, and more. Popular options include:

• Philips Hue Smart Light Switches
• Lutron Caseta Smart Light Switches
• Leviton Decora Smart Switches

These provide integrated motion sensing capabilities without needing separate sensor modules. Plus they allow control of lights right from your phone and integration with home automation platforms.

The installation process is similar, just make sure to get a smart switch made specifically for your type of wiring (neutral wire required, 3-way switches, etc.)

Conclusion

Adding motion sensing to existing lighting provides many benefits like automated control, increased convenience, improved security, and greater energy efficiency. Thankfully wiring motion sensors to your existing interior and exterior light fixtures is totally doable as a DIY project.

Just make sure to shut off power, get a compatible motion sensor for your wiring and lighting load, connect the wires securely using provided wire nuts, mount the sensor properly, turn power back on, and adjust settings as needed. Follow safety precautions when working with electrical wiring. With a little time your existing lights can now function automatically hands-free!

Frequently Asked Questions about Adding Motion Sensors to Existing Lights

What are the benefits of adding motion sensors to lights?

The main benefits of adding motion sensors to existing lights include:

• Hands-free automated light activation – Lights turn on and off based on occupancy and ambient light levels.
• Increased safety and security – Motion activated lights can deter crime and make entryways safer at night.
• Energy savings – Lights only turn on when needed instead of staying on constantly.
• Flexible lighting control – Sensors allow easy adjustment of the activation range, duration, light levels, etc.

What are the cost considerations?

The main costs involved in adding motion sensors to lights include:

• Motion sensor unit – Prices range from $10-$100 depending on detection features.
• Electrical boxes – New exterior electrical boxes range from $5-$20 for installation.
• Wiring – New wiring if existing wiring cannot accommodate a motion sensor.
• Electrician fees – Around $40-$100 per hour if choosing to hire an electrician for installation.

Many times the existing wiring can handle new motion sensors. Overall, adding motion sensors represents an inexpensive way to upgrade existing lights.

What kind of motion sensors are best for exterior lights?

For exterior lights, you’ll want to choose an outdoor-rated motion sensor with the following features:

• Weatherproof IP65 or higher rated housing
• Temperature compensation or dual sensing to prevent false triggering
• Detection range up to 40 ft or more
• Field of view up to 240° for wide coverage
• Adjustable light duration and sensitivity settings
• Quick installation wiring
• Clear motion sensor lens cover

Units with photocells, LED compatibility, and smart features are also useful for exterior security lighting.

How do I prevent false motion sensor triggering?

To prevent false triggering of motion sensor lights:

• Adjust the motion sensitivity down or detection range to cover only needed areas
• Use “dual” motion+temperature or motion+ambient light sensors that verify motion before triggering
• Set an appropriate light duration time so the light doesn’t stay on too long after motion stops
• Position the motion sensor to avoid picking up moving objects like branches, cars, birds, etc.
• Install a motion sensor with temperature compensation to prevent triggering from heat sources like AC units

Properly installing and adjusting motion sensors for your specific situation is key to avoiding false activations.

Comparisons of Motion Sensor Types

There are a few main options when choosing motion sensors for lighting automation:

Integrated LED Motion Lights

• All-in-one motion sensor and LED light fixture
• Fully self-contained and wireless using batteries or solar power
• Designed for easy outdoor installation on walls or under eaves
• Limited customize-ability since the light source is integrated

Wired AC Motion Sensors

• AC powered motion sensors that wire into existing junction boxes and light fixtures
• Hardwired to control externally wired lighting loads
• Compatible with all light bulb types – LED, incandescent, fluorescent, etc.
• Require wiring but allow motion control of your existing lights

Smart Light Switches with Motion Sensors

• Replaces existing light switches to enable app control via smartphone
• Built-in motion and ambient light level sensing capabilities
• Lets you automate lights via scheduling and remote access too
• Requires neutral wires in switch electrical boxes

The best option depends on your specific needs, lighting setup, and budget. Smart switches provide the most features but at higher cost.

Motion Sensor Selection Criteria

Feature	Considerations
Detection Type	PIR, Microwave, or Dual Tech motion sensors
Detection Range	Sensing distance like 30 feet – match to space size
Lighting Load	Sensor power rating must meet light wattage
Indoor vs. Outdoor	Outdoor sensors need IP65 rating and wider temps
Customizations	Adjustable settings, timers, light levels, multiple heads

Consider the detection performance, electrical loads, location, and customizations needed when selecting a motion sensor model. The right motion sensor ultimately depends on your specific lighting automation needs and setup.

Cost Comparison of Motion Sensors

Motion Sensor	Cost
Corded Wall-Mounted	$15-$50
Wireless Battery-Powered	$40-$80
Integrated LED Security Light	$80-$150
Smart Light Switch	$40-$100

Prices vary based on detection features, lighting load capacities, durability, and smart capabilities. Simple indoor motion sensors are most affordable, while premium smart outdoor options with more features run higher. Labor costs also apply for installation.

How to Troubleshoot Motion Sensor Issues

Having problems with your motion sensor lighting? Try these tips:

• Verify the motion sensor has power – check bulb, fuse, wiring
• Check motion sensor settings like duration, sensitivity, daylight sensor
• Adjust motion sensor positioning to cover the desired area
• Look for physical obstructions blocking the sensor’s view
• Clean dirty motion sensor lenses gently with cloth and water
• Make sure light bulbs do not exceed sensor wattage ratings

For smart motion devices, also check Wi-Fi connectivity.Follow troubleshooting steps in the manufacturer’s instructions. Most motion sensor issues can be fixed with simple adjustments, wiring checks, and cleaning.

Conclusion

The flexibility and convenience of motion activated lighting is hard to overstate. With a simple wired motion sensor unit, you can easily automate existing exterior security and accent lighting. The installation process is straightforward with minimal wiring changes needed in most single pole switch configurations. Just be sure to select a motion sensor suited for your specific lighting load, location, and features needed. With a small investment of time and money, you can enjoy hands-free, energy efficient lighting automation.