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How To Wire A Motion Sensor To An Existing Light


For most homeowners, the thought of handling electrical wiring can be daunting. However, with the right knowledge and tools, anyone can learn to do basic electrical tasks, such as wiring a motion sensor to an existing light. In this article, we will guide you through the process of wiring a motion sensor to an existing light, step by step. But before we dive into the details, let us introduce ourselves.

B&K Electric is a family-owned and operated electrical business based in Warwick, RI, that is rooted in community and customer service. We’re owner-operated and our electricians have been proudly serving the residents of Cranston, Warwick, and all of Rhode Island for over seventeen years. We specialize in electrical repair, electrical panel maintenance, and installation. We understand that electrical work can be complicated and overwhelming, which is why we’re here to help simplify the process for you. So, if you’re looking for a licensed electrician to service your residence in Cranston, Providence, or anywhere in the United States, B&K Electric is the go-to choice.

Wiring a motion sensor to an existing light is a great way to enhance the security and convenience of your home. With this simple addition, your outdoor light will automatically turn on when someone approaches, making it easier for you to navigate without fumbling with a light switch in the dark. Plus, it can also act as a deterrent to potential intruders. So, let’s get started!

Step 1: Gather the Necessary Tools and Materials

Before getting started, make sure you have all the required tools and materials handy. You will need a voltage tester, wire cutters, wire strippers, pliers, a screwdriver, electrical tape, wire nuts, and the motion sensor itself. You can purchase the motion sensor at any hardware store or home improvement center, or you can consult with a licensed electrician and have them recommend a reliable motion sensor for your specific needs.

Step 2: Turn Off the Power

Safety should always be the top priority when working with electricity. It is crucial to turn off the power to the circuit that you will be working on. Locate the circuit breaker box in your home and flip the switch that controls the power to the outdoor light you will be working on. Once you have shut off the power, use a voltage tester to ensure that the power is indeed off before proceeding.

Step 3: Gain Access to the Light Fixture

To access the light fixture, remove the screws or fasteners that secure the fixture to the wall or ceiling. Once the fixture is loose, carefully unscrew the wire nuts that connect the wires from the light fixture to the wires inside the electrical box. Be sure to note which wires are connected to each other so that you can reconnect them correctly later.

Step 4: Run the New Electrical Cable

Next, you will need to run the new electrical cable from the light fixture to the motion sensor. Start by drilling a hole near the light fixture that is large enough to fit the new cable through. Then, carefully thread the cable through the hole and secure it in place using appropriate fasteners.

Step 5: Connect the Motion Sensor

Now it’s time to connect the motion sensor to the existing wiring. If you’re not sure which wires to connect, refer to the manufacturer’s instructions. Generally, you will connect the black wire from the sensor to the black wire from the fixture, the white wire from the sensor to the white wire from the fixture, and the green or copper wire from the sensor to the ground wire in the electrical box.

Step 6: Mount the Motion Sensor

Once everything is connected, mount the motion sensor in the desired location using screws and a screwdriver. Make sure the sensor is facing the area you want it to detect motion.

Step 7: Test the Motion Sensor

With the power still off, test the motion sensor to ensure that it is working properly. Turn the power back on and walk in front of the sensor, and the light should turn on. If your light does not turn on, go back and check all the connections to make sure everything is secure and correct.

Step 8: Reconnect the Wires

If the motion sensor is functioning correctly, it’s time to reconnect the wires from the motion sensor to the wires inside the electrical box. Make sure to secure the connections with wire nuts and wrap them with electrical tape for extra security.

Step 9: Reattach the Light Fixture

Finally, reattach the light fixture using screws or fasteners. Then, turn on the power, and your motion sensor light is now ready to use.


Wiring a motion sensor to an existing light is a straightforward and beneficial project that can improve the safety and convenience of your home. However, if you’re not comfortable with handling electrical tasks, it’s always best to consult with a licensed electrician to ensure the job is done correctly and safely. At B&K Electric, our experienced electricians are always ready to assist and provide top-notch service to our valued customers. Feel free to contact us for all your electrical needs.


Motion Sensor Wiring,

Electrical Repair,

Home Improvement