What Is a Motion Sensor?
Motion Sensor is a device that detects movement within a defined area and signals a light or control system to respond. Common sensors detect changes in infrared energy, sound waves, or reflected microwaves. In security lighting, the sensor turns a connected fixture on when movement meets its detection settings, then allows the light to turn off later.
Quick Facts About Motion Sensor
Category
Lighting control device
Used for
Automatic security lighting
Common confusion
Motion sensor versus photocell
Also called
Occupancy Sensor, Movement sensor
Often discussed with
Security Lighting Installation
Key Takeaways About Motion Sensor
- Detection technology varies by sensor design.
- Placement controls coverage and unwanted activation.
- A motion sensor is not the same as a photocell.
How Motion Sensor Works
Motion Sensor operation begins when the device monitors a detection zone for a change. A passive infrared sensor responds to changes in heat patterns, while other designs detect movement through sound or radio signals. The sensor sends a control signal when activity matches its settings.
Related glossary terms: Photocell, Line Voltage.
The connected light then switches on through its control circuit. Coverage depends on mounting position, viewing direction, and objects that block the sensing area. Sensitivity and shutoff settings also affect operation. A photocell responds to ambient light levels, so it can control a fixture at dusk even when no person or vehicle moves nearby. A timer switch follows a schedule instead of reacting to movement.
From the San Bernardino Electrician team
When we install or inspect a motion sensor, we check the power connections, sensor orientation, fixture compatibility, and detection area. We also test operation from likely approach paths and adjust settings to limit unwanted activation from nearby streets, trees, or animals.
Motion Sensor in Practice: A Real-World Example
A homeowner may use a motion sensor with a wall-mounted security light near a side gate. The fixture activates when a person enters the gate area, giving the property immediate illumination without leaving the light on continuously.
Related Services
Related Terms
Photocell
Photocell is a light-sensitive electrical control that switches outdoor lighting on when surrounding light fades and…
Line Voltage
Line Voltage is the electrical pressure supplied by a power system to operate equipment, lighting, and…
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