What Is a Photocell?
Photocell is a light-sensitive electrical control that switches a lighting circuit on when surrounding light becomes low and switches it off when daylight returns. A photocell helps outdoor fixtures operate automatically without a manual switch. It is commonly used for security lights, pathway fixtures, wall packs, parking-area lighting, and other dusk-to-dawn applications.
Quick Facts About Photocell
Category
Automatic lighting control
Used for
Dusk-to-dawn outdoor lighting
Common confusion
Photocell versus motion sensor
Also called
Light sensor, Photoelectric sensor
Often discussed with
Lighting installation
Key Takeaways About Photocell
- Light level, not motion, activates a photocell.
- Placement affects how accurately the sensor reads daylight.
- A photocell is not the same as a motion sensor.
How Photocell Works
Photocell operation depends on a light-sensitive component that changes its electrical behavior as ambient light changes. The control sends power to a connected fixture during darkness, then interrupts power as daylight increases. This cycle repeats automatically each day without requiring someone to operate a wall switch.
Related glossary terms: Smart switch, Three-way switch, Dimmer switch.
Installation position affects the sensor's reading. A photocell facing a porch light can detect that fixture's glow and switch off too soon. Nearby trees, eaves, reflective surfaces, or other lights can also affect operation. Some controls are built into a fixture, while others mount in an exterior electrical box and control separate LED lighting. A timer switch follows a scheduled time, while a photocell responds to actual light conditions.
From the Center Electric Service team
When we install or troubleshoot a photocell, we check its position, wiring, and connection to the lighting load. We also test the control under changing light conditions and look for nearby fixtures that could influence its reading. Proper placement helps the sensor respond to the surrounding area instead of a small, misleading light source.
Photocell in Practice: A Real-World Example
A Riverside property owner wants a wall-mounted exterior light to operate from dusk until daylight. During a lighting installation, we can connect the fixture to a photocell and position the sensor where the fixture's own light does not shine directly on it.
Related Services
Related Terms
Smart switch
A smart switch is a wall-mounted control that operates lighting or other connected loads and communicates…
Three-way switch
A three-way switch is a wall control that lets you operate one light or fixture from…
Dimmer switch
A dimmer switch is a wall control that adjusts the electrical power delivered to a compatible…
Center Electric Service
Have Questions About Photocell?
Contact Center Electric Service for practical guidance on Photocell and related electrical services work in Riverside.