How to Wire a Photocell to Multiple Lights

Are you looking to add photocell lighting control to more than one light? By wiring a photocell to multiple lights, you can have them turn on and off automatically, depending on the amount of light in the area.


This article will show you how to wire a photocell to multiple lights. Installing a photocell is a great way to control the light in your outdoor space.

By wiring a photocell to multiple lights, you can have them turn on and off automatically, depending on the time of day. In this article, we’ll show you how to do just that. Read on for step-by-step instructions.

Summary: Wiring a photocell to multiple lights is an efficient way to automate the control of outdoor lighting systems, ensuring that they turn on at dusk and off at dawn. This not only helps save energy but also enhances security around your property. Before starting the wiring process, gather the necessary materials and tools, including a photocell, wire nuts, electrical tape, and a screwdriver. Additionally, ensure that the power is turned off at the circuit breaker to avoid the risk of electrical shock.

To wire a photocell to multiple lights, begin by identifying the input wires from the photocell, which typically consist of a red (load), white (neutral), and black (line) wire. Locate the electrical junction box where the multiple lights are connected, and find the corresponding wires that supply power to the lights. First, connect the white neutral wire from the photocell to the white neutral wires from the lights using a wire nut, and secure the connection with electrical tape. Next, connect the black line wire from the photocell to the black line wire supplying power to the junction box, again using a wire nut and electrical tape.

Finally, connect the red load wire from the photocell to the black wires from the lights, following the same process. Once all the connections are made, carefully tuck the wires back into the junction box and secure the photocell in its designated position. Restore power at the circuit breaker and test the functionality of the photocell to ensure the lights turn on and off as intended.

What Is a Photocell and How Does It Work?

A photocell, or light receptor, is a device that detects visible or infrared (IR) light. When the cell receives light, it emits an electrical current.

This current can be used to control other devices, in this case, appliances such as lights and fans.

A basic photocell consists of two terminals that are connected via a resistor. The light hitting the cell causes a resistance change based on its intensity.

Photocells are often used with appliances that have an on/off function. If the appliance is turned on, the photocell will detect the visible or infrared light and complete the circuit to turn it off.

However, if there is no visible or infrared light, the photocell will not complete the circuit, and the appliance will not turn on.

Seven Methods on How to Wire a Photocell to Multiple Lights:

1. Power Splitter:

Photocells run on low voltage. What is required for this type of wiring is a small power splitter that will allow you to split the power source into two, three, or even four outputs. The photocell plugs into one output, and your lights plug into another.

2. Power Switch:

Another way to wire a photocell to multiple lights is with a power switch. This method will allow you to turn on and off the power source at the switch. This is probably the most popular method for wiring photocells into multiple lights.

3. Relay Box:

Another way to wire a photocell to multiple lights is with a relay box. However, this requires more wiring than the power switching method because you will need to wire each light to a relay, then each relay to the switch, and control all of the relays with your photocell.


4. Power Multiplexing:

Another way to wire a photocell to multiple lights is by power multiplexing. Power multiplexing allows you to use an SPDT (3-prong) standard toggle switch that only requires AC voltage and three wires instead of two.

Because this method uses an AC component, it will work with any lamp design and won’t affect the system’s polarity.

5. Transfer Box:

Wire the power cord to travel through this box. The size of your lamp should be chosen according to the sq. inches in your transfer box. If you are not using a pre-wired lamp, a number will be provided on the lamp’s box.

If your project is more complex than one light-box or you’d like to integrate a photocell, cut all cords at once and wire them together, so only one cord needs to be fed through transfer boxes.

6. AC Decoupling/Isolation Method:

This method is used for wiring a photocell sensor to multiple lights without an additional power source. It requires all of the light bulbs being used to have their own AC cord that runs straight into the power supply.

The photocell must be wired into each light circuit not to receive power from anything else but the lamp itself.

7. External Photocell:

This method serves as a fail-safe. If your original photocell stops working for any reason, you will be able to easily replace it without having to rewire anything or reattach the wire from the switch.

Instead, you plug the external photocell into the wall and attach your lights to that cord. This is only used as a temporary fix, so it should not be used if you need to control multiple lights with one photocell for an extended time.

Some Tips and Suggestions

Here we have given some tips and suggestions on how to wire a photocell to multiple lights.

1. Always have your photocell facing the outside of the house. This will ensure that it is always lit up by direct sunlight, which will give you maximum brightness to determine whether or not your lights should be on.

2. Do not buy a super cheap one; they are more trouble than it’s worth! Instead, spend some extra money on a quality photocell, and it’ll last you a lot longer and provide better results.

3. Make sure that if the photocell is outside, it is protected from any bad weather or debris such as leaves or branches that could potentially trigger your lights on when they’re not supposed to be on.

4. If there’s any sign of condensation or water on the photocell, dry it off as soon as possible because if too much water gets near or inside the photocell, you might have a short circuit that could fry your whole system.

5. If your photocell does go out and you need to replace it, buy a new one that’s exactly the same as the previous one. This way, your timers will still work the same way as before.

How Many Watts Can a Photocell Handle?

A photocell is a device that turns the power to an electric circuit on and off in response to light. They come in different sizes and can be purchased for use with low-voltage currents, such as the type used by lights, or higher voltages.

For example, household wall sockets are powered at 120 volts AC (alternating current), whereas a photocell is powered at 12 volts DC (direct current).


A basic photocell has two terminals, known as the anode and cathode. One terminal is made from metal, typically copper or aluminium.

The other may be made of silver, gold, or any other metal. When the cell receives light on the metal side, it causes the voltage to decrease. When light is blocked, it causes the voltage to increase.

Put, the more power (watts) applied through a photocell, the greater its resistance will be. That means that applying too much power will overpower or blow out the cell.

Photocells are typically rated at about 1 watt of resistance each; however, they can be used for devices that require much less wattage.

How to Install the Photocells?

Purchase the right photocells for your project. Please make sure they are compatible with whatever you intend your circuit to control.

For example, you cannot control lighting or electrical appliances like refrigerators with solar cells; you can only control lights. Photocells and LED lights should not be connected in series.

They should be wired in parallel with each other. Photocells can detect light levels, and LEDs that receive the signal from the photocell will turn on when exposed to that light.

Connecting them in series will cause a short circuit because they both work off of electricity, burning the photocell. Photocells will work in a circuit with LED lights, but nothing else.

Safety Precautions When Installing or Using a Photocell

1. Photocells are designed with AC (Alternating Current) light sources. Please do not use them with DC (Direct Current) or household current, like your wall outlets or switches.

2. Photocells will not work properly if exposed to direct sunlight, artificial lighting containing UV (Ultra-Violet) radiation, or strong magnetic fields.

3. Photocells cannot be used as a safety cutout with household current and must not even be exposed to it! You could get electrocuted by touching the terminals of a photocell that’s been exposed to household current.

4. Photocells are not designed to activate an electronic device that requires a load of more than 16 amps or 10 watts and should not be used as a switch for devices like heat lamps.

5. Unless otherwise stated in the product description, photocell connections must never exceed 600 volts! This means you should use proper relays to control high voltage devices like HID (High-Intensity Discharge) lights.

6. Photocells are not designed for outdoor use. If you wish, you can install them indoors and cover the terminals with weatherproof tape or enclose them in a plastic or metal housing, but be aware that they will not last long if exposed to the weather.

7. Photocells should always be connected to a device’s pilot light’s leads, not directly to AC power itself. This allows your lights or appliances to turn on at night without wasting energy!

Can Photocells Be Used With LEDs?

Yes, photocells can be used to control LEDs. The photocell is a device that detects light and will allow the LED to turn on if the room has adequate light.

They are often used to control outdoor security lights because they do not need an additional power source.


Photocells are great for turning lights on or off depending on the amount of light, making them excellent for LEDs.

If you want to know more about how to wire a photocell to multiple lights, check out this full blog post.

Do Photocells Need Neutrality?

Many people think that the photocell must be grounded for it to work. Not so! The photoelectric process is one of converting light into electricity.

It does not involve any current or voltage (no pressure), and therefore doesn’t require a zero-pressure reference like the earth.

So while you could wire your photocells to a neutral, many people have done so successfully without it.

The one thing you should never do is hook up the photocell across the two hotlines as the cell will get fried! Photocells are also often confused with photovoltaic cells, which are neutral but not photocells.

Final Verdict

In this blog post, we have gone over how to wire a photocell with multiple lights. To do so, you need an outlet timer and two photocells.

The first step is connecting the wires from one of the photocells into the outlet timer and then plugging it in. Next, take another set of wires and connect them at both ends.

Finally, place the second photoresistor on top of or near where you want more lighting coverage for better visibility during nighttime hours.

Turn off any nearby lamps once all wiring connections are made up correctly before setting your new timing schedule. Then, if you need to, rewire or troubleshoot the connections until the lights turn on and off at the right times.

Do you know how to wire a photocell to multiple lights? Would you try this project if it were for educational purposes only? Feel free to leave any additional questions or comments below. Thanks for reading!

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