What Is a Photocell?
Photocell is a light-sensitive electrical control that switches outdoor lighting on when surrounding light falls and off when daylight returns. The device responds to ambient light, so fixtures can operate automatically without a manual switch. Photocells are commonly installed with landscape, security, pathway, and other exterior lighting systems.
Quick Facts About Photocell
Category
Light-sensitive control
Used for
Automatic outdoor lighting
Common confusion
Motion sensor
Also called
Dusk-to-Dawn Sensor, Light sensor
Often discussed with
Outdoor Lighting Installation, Landscape Lighting Installation
Key Takeaways About Photocell
- A photocell responds to ambient light, not motion.
- Proper placement helps prevent unwanted switching.
- A photocell is not the same as a motion sensor.
How Photocell Works
Photocell uses a light-sensitive sensor to detect the brightness around an outdoor fixture. As daylight fades, the sensor changes the control circuit and allows the light to turn on. When daylight returns, the circuit changes again and turns the light off. This process gives exterior lighting an automatic day-and-night schedule.
Related glossary terms: Landscape Lighting Transformer.
Installation position affects performance. A sensor aimed toward a fixture may detect the fixture's own light and switch repeatedly. Nearby porch lights, reflective surfaces, shade, and dirt can also affect the reading. A timer switch follows a programmed schedule, while a motion sensor responds to movement. Some outdoor lighting systems combine these controls when the design calls for both dusk operation and activity detection.
From the Earth Electric team
When we install or service a photocell, we check its placement, wiring, and connection to the outdoor lighting circuit. Our team also tests the control under changing light conditions and looks for nearby fixtures or surfaces that could affect the sensor. We verify that the light responds as intended.
Photocell in Practice: A Real-World Example
A homeowner wants pathway lights to operate from dusk until dawn. A photocell installed where it can read natural outdoor light can switch the fixtures on after sunset and off after sunrise without daily manual control.
Related Terms
Landscape Lighting Transformer
Landscape Lighting Transformer is a device that converts household electrical power to the lower voltage used…
Earth Electric
Have Questions About Photocell?
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