Let’s get right into it. A photocell is a small sensor that helps a light fixture know when to turn on or off based on how dark it is outside. That’s it.
You’ve probably used one without even knowing it. If your porch light comes on at sunset and shuts off in the morning, there’s a photocell involved.
Let’s break it down.
Key Takeaways
- A photocell is a sensor that reacts to the amount of light around it.
- It’s often used to automatically turn lights on at night and off during the day.
- It helps save energy, adds convenience, and makes outdoor lighting hands-free.
- You’ll find it in porch lights, flood lights, street lamps, and even holiday decorations.
How Photocells Work
A photocell measures the light level in the area around it. When it gets dark, the sensor triggers an electrical circuit to power the light. When it gets bright again, it cuts power.
Here’s the basic idea:
- Low light = power flows = light turns on
- Bright light = power stops = light stays off
That’s why your lights can automatically turn on at night without a timer.
It’s a simple setup. The photoelectric cell inside the sensor detects natural light. The amount of light it sees decides whether the electrical circuit stays open or closed.
No programming. No apps. Just automatic control based on actual light.
Where You’ll Find Photocells
They show up in more places than you think.
- Outdoor wall lights
- Street lights
- Parking lot lights
- Landscape lighting
- Flood lights
- Motion lights with dusk-to-dawn features
- Solar lights
Basically, anywhere you want a light fixture to turn on or off without you touching a switch.
Photocell vs Timer vs Motion Sensor
Let’s clear this up. People confuse these all the time.
| Feature | Photocell | Timer | Motion Sensor |
|---|---|---|---|
| Triggered by | Natural light | Scheduled time | Movement |
| Use case | Dusk-to-dawn lights | Regular routines | Security lights |
| Manual override | Sometimes | Yes | Usually |
If you want lights to follow the sun, go with a photocell. Timers need resetting. Motion sensors aren’t reliable for dusk-to-dawn use.
Common Problems With Photocells
Photocells are pretty reliable, but they’re not perfect. Here’s what can go wrong:
- Artificial light hits the sensor – It thinks it’s daytime and shuts off the light.
- Sensor gets blocked – Dirt, spider webs, or leaves can stop it from reading light.
- Moisture damage – Outdoor sensors should be weather-rated, or they’ll fail fast.
- Age – Like anything, they wear out. If your light stays on 24/7, check the sensor.
Most of these are easy fixes. Clean the sensor. Reposition it. Or replace it if it’s dead.
Choosing the Right Photocell
If you’re buying a new photocell or replacing an old one, here’s what matters:
- Indoor or outdoor use? Make sure it’s weatherproof for outdoor setups.
- What kind of bulbs? Some sensors don’t work well with LEDs.
- Voltage? Match the sensor to your fixture’s power rating (120V, 277V, etc).
- Mounting location? Keep it away from artificial lights that might trick it.
Cheap photocells work fine in most cases. Just don’t put them where they’ll get blocked.
Need Help Installing One?
If you’re in Centennial, CO or the surrounding areas, Genesis Electrical can handle your photocell installation.
We’ll wire your light fixtures to automatically turn on when the sun goes down and shut off when it’s back up. No timers. No switches. Just set-it-and-forget-it lighting that works.
Give us a call or schedule online.
Good day, and Gooooooood Genesis!
FAQs
Do photocells work with LED lights?
Yes, but make sure the photocell is LED-compatible. Some older models don’t work well with low-wattage bulbs.
Can I use a photocell indoors?
Technically yes, but it’s not ideal. Light levels change too often inside, and artificial light can confuse the sensor.
Do photocells go bad?
Yes. Like most electronics, they wear out. If your light stays on or off all the time, the sensor might need replacing.
Can I bypass a photocell?
Yes. Some fixtures have a manual override. Or you can rewire it. But if you do that, it defeats the point of automatic lighting.
How do I know if my light has a photocell?
Look for a small black bubble or sensor on the light fixture. If it turns on at night and off in the morning, that’s your clue.