Before I proceed to explain how to wire a photocell to multiple lights. Allow me to say that a photocell is an electrical device that is controlled by light. How does light work with a photocell?. A photocell is a light-controlled resistor.
I am going to limit myself to discuss the photocell used to switch on the outdoor security lights. In simple terms, a photocell will switch on the lights when it is dark and it will switch off when there is light.
In day to day application, a photocell will automatically switch off the lights in the morning. In the evening it will automatically switch on the lights.
A photocell eliminates the worry of forgetting to switch the security lights on and off. Below is a step by step guide on how you can wire a photocell to multiple lights.
- 1 A step by step guide on how to wire a photocell.
- 2 Photocell with contactor.
- 3 Common problems with photocell.
- 4 Final thoughts and other application of a photocell.
A step by step guide on how to wire a photocell.
- You Know the number of lights that you want to install.
- Determine the number of circuits that you will have
- Know if you will share power with indoor lighting.
- Install electrical conduit pipes
- Fish in the wires.
- Install the light fittings
- Mount and connect the photocell.
Know the number of lights that you want to install.
This is the first step in installing a photocell to multiple lights, which Is knowing the number of lights that you need to install. Knowing the number of lights is going to help you to determine the correct size of a photocell. What do I mean most photocells have a power rating in watts.
The power rating tells you how many lights can be controlled by this photocell. Of course, this is determined by the wattage of the lights you wish to install.
Determine the number of circuits you will have.
How do you determine the number of circuits? You look at the total number of lights you have. Then you check the power rating. After that, you calculate the current that each light will draw from the supply.
For example, if you are using a 10A circuit breaker, you have to ascertain how many lights it can supply. When you discover that you have more lights than what a single 10A circuit breaker can carry. You must introduce another circuit to supply power to the other lights.
There are instances, where you might decide to you use a power supply from the existing indoor lighting circuits. I would not encourage you to do this When you have a lot of outdoor security lights that you want to install. The best practice is to create a separate circuit for the lights being controlled by a photocell. You can add security lights, to the existing indoor lighting circuit when you are just adding one or two lights.
Install electrical conduit pipes.
When you know how many lights you are going to install, it is easy to do your electrical conduit piping. Now you are in a better position to execute your plan.
At this point, you know the number of circuits you are going to have. This gives you a clear picture of how you are going to route your conduit pipes to achieve your goal.
Fish in the wires.
Once you have finished your electrical tubing work, it’s time for you to pull cables through the conduit pipes. This is a very critical part of wiring a circuit controlled by a photocell.
A photocell comes with three terminals or three cables for the purpose of connecting power to it. I will talk more about these cables in the next section. You fish in your cables in such a way that when you finally complete your wiring works, you will be able to connect the photocell without any difficulties.
Mount and connect the photocell.
You mount a photocell in such a way that when the lights are switched on, it doesn’t trigger the photocell to turn the light off. Put in a position that will make it switch on the lights in the evening and switch off the lights in the morning.
A photocell is a switch therefore, it has a common terminal and load terminal or switch wire. The three terminals that are used to connect power to a photocell are labelled.
How do you connect power to the photocell? You connect the live wire that comes from the circuit breaker to the terminal labelled common.
You connect the wire that takes power to the installed lights to the terminal labelled load. The neutral wire you connect it to the terminal is labelled neutral.
At times the terminals are not labelled as above. But they are labelled as below.
- Neutral: This is where you connect your neutral.
- Line:This is where you connect the live or hot wire.
- Load.This is your switch wire.
These wires come with a colour code. I have decided not to mention the colour code that represents the neutral wire, the load wire and the common wire. It’s because the colour code differs from place to place. The only safety is to read the installer’s manual. The manual will tell you colours that represent the three-terminal.
Photocell with contactor.
When you have a lot of lights, that can not be carried by a photocell alone. You will need the help of a contactor to switch on the lights.
How does a contractor work in conjunction with a photocell? A contactor is a magnetic switch that is actuated by a small current. Instead of a photocell to carry the full load of the lights, the switch wire connected to the lights gets its power from the circuit breaker through the contactor.
How do you connect the wires to both a contactor and photocell.
- You run electrical cable from the the circuit breaker in consumer unit.to the contactor.I must mention that you the cables arcording to the number of lights circuit.For example,if you have 3 circuits,you run 3 cables from the DB to the contactor.
- You connect the cables from the DB on the terminals labelled L1, L3,L5.On the contactor.You connect the supply cables on the main contactor conttacts.
- Connect the cables going to the lights on the terminals labelled L2,L4,L6.
- You connect the cable comming from the photocell to the terminal labled A1 on the contactor.
- The job of a photocell in this circuit is energize the contactor.
- when the contactor is energised,the lights are switched on.
Common problems with photocell.
- They can shut off unexpectedly during the night,due to light that can mistakenly fall on the photocell.
- The light can be on during the day.This can be a result of dust and shading.Sometimes this can happen when some component in the photocell are blown out.In this case you should replace it with a new photocell.
- Photocell can fail due to loose connections in the terminals.
- I have also seen that a short circuit in the lighting circuit can cause a photocell not to work properly.This is common with led security lights.
Final thoughts and other application of a photocell.
Photocell is a good photoelectric switch. When you want your lights to be switching on automatically in the evening, Install a photocell. A photocell has a lot of application in real life . Check a list of some of application of a photocell below.
- Control temperature of a furnace.
- Used in space travel to obtain electric energy from sunlight.
- Can be used in sound production that can be recorded on a movie film.
- Intruder alarms and automatic doors.
- Used as a timer in running race to calculate a runners speed.
Do you have any questions? on how to wire a photocell to multiple lights. leave your comments below in the comments section.