how to wire a motion sensor to an existing light image

Quick Guide on Installing a Motion Sensor to an Existing Light Fixture

Motion sensors function by sensing and measuring movement. They form an essential part of many homes and business security systems. On questioning, a large percentage of convicted burglars revealed that outdoor lighting and installed security systems are excellent deterrents while considering their targets. Lights with motion sensors help save on electricity. Because they burn only in the presence of an occupant instead of burning all day. Wondering how to wire a motion sensor to an existing light? If you love your present light bulbs to the level that you don’t want to remove, but want to add security system, just follow the below 7 steps.

How to Wire a Motion Sensor to an Existing Light?

A user can wire a motion sensor for existing lights in order to make it work as a motion sensor bulb. Wiring an inside or outside light with sensor can be done just by using a screwdriver and a motion sensor switch. You can act by the following set of instructions given below:

  1. Pick out a motion sensor kit. Ensure that the existing light possesses an opening to screw into; you need to connect the motion sensor in this opening.
  2. Turn off the power connection to the light and remove the cover. Ensure that the power is off before working on the wires to eliminate any risk of an electric shock.
  3. Using a volt detector, test the wires and make sure they are dead. 
  4. Remove the insert from the light where we need to install the motion sensor.
  5. Now, screw the motion detector into the light fixture in the above-mentioned spot.
  6. In order to connect the wires, connect the existing black (hot) wire to the black wire of the motion sensor. After securing this connection, connect the neutral wires of both together.
  7. Adjust the sensitivity as per your requirement. Calibrate the detector and close it up by securing all connections.

As a advise, it is better to apply for an electrical permit at the local inspections department in order to get an inspector to verify the security of your work.

Best Places for Motion Sensor Light Installation

  1. Corner Spaces: Place the motion detectors in the corners of each room, aiming at the doorway. This will be an inconspicuous spot which ensures that no one can enter without setting off the alarm
  2. Within Decorations & Near Valuables: Hiding the sensors between knick-knacks and pictures makes them less conspicuous. Also, if there are any valuables that you want to protect so hard, then better use these motion sensor lights near them.
  3. Outside Patios: This placement allows you to monitor any movement near your back door. For better security, you can also include motion sensor to the light bulbs near front door, side door, other entrance points.
  4. Basements: In most cases, basements are a common entry point for intruders because of their accessible windows. So, it is better to place a motion sensor in your basement in the spot where you can see the entire space.
  5. Ceilings: Most intruders are mindful of security systems and motion detectors and may be equipped to detect and disable the same. However, they are less likely to consider or immediately spot any motion detectors attached to the ceiling.

Least Effective Places for a Motion Detector Wiring

Some of the least effective placements for a motion sensor are as follows:

  1. Near windows: If the sensor is heat-activated, placing them near windows, where sunlight will fall on it, the sensor may be activated by the sunlight.
  2. Near heat sources: The heat from some sources like air vents and radiators could lead to faulty detection and create a false alarm.
  3. Behind large furniture: These may create blind spots and reduce the efficacy of the motion detector of your security system.
  4. Garages, attics, sunrooms: These spaces are not climate controlled and hence tend to heat up, which might cause false alarms.
  5. Stairs: If you have pets, avoid placing the motion sensor near the stairs in order to make sure they don’t set off alarms. Pets look larger as they climb up the stairs and may be mistaken for intruders by the sensors.

How Can We Prevent False Alarms?

The efficacy of motion sensors is highly dependent on their placement and upkeep. New systems usually ignore anything that’s under 2.5 feet or weighs under 85 pounds. The following are a few things to keep in mind to determine the best possible location for the motion sensors:

  • Your pets
  • Curtains, plants, etc. may be blown by the wind and cause the sensor to detect movement
  • Batteries and electrical connections
  • Ceiling fans that may set off the detector
  • Any moveable objects near the motion sensor

Problem facing with your existing detector? Now, you can easily fix it by resetting motion sensor light using breaker method or light switch method.


1. Can you add a motion sensor to an outdoor light?

Ans: Yes, you can add on motion sensor to an existing outdoor light. If you do not want to change your exterior light bulbs, you can simply add a motion sensor following the process mentioned earlier. Else, you can just change your outside lights with sensor bulbs.

2. How do motion sensors work?

Ans: Motion sensors work on a passive system that detects infrared energy called PIR (Passive Infrared Detectors) or pyroelectric sensors. They detect anything that emits a heat signature, the human body being an example of the same. They also pick up on other specific cues like vibrations or radiations. When a person walks by, there is a shift in the infrared energy associated with that particular region, which tips off the associated system; alarms in the case of security systems.

3. How do you turn off a motion sensor light?

Ans: In order to turn off a motion sensor light, you can aim a powerful, narrow beam of a flashlight at the sensor or disconnect the source of electric power from the light.


Motion sensors have been behind the revolution of security technology. They made many home and business owners to rest assure. Attaching motion sensors to existing lights is easy if you keep in mind all the factors previously stated in this article. Now, one can set up a fool-proof defense system and keep themselves safe from all external threats.