Last Updated on October 22, 2023 by Kevin Chen
Image credit upgradehome
You want to upgrade the lighting in your home or even in a commercial place. Let’s say the building has a 20-amp circuit breaker. While trying to achieve this goal, you are concerned by one key factor: circuit breaker overloading. This is where the issue concerning the number of light fixtures comes in.
Which is the ideal number for the 20-amp circuit breaker? Let’s discuss and find out the answer.
Watts of light fixtures
Each lighting fixtures that you want to install has a fixed or designated wattage. This is the amount of power that is consumed by the light fixture. It is also the amount of power that must be supplied by the circuit breaker in order to run it.
A 20-amp circuit breaker can comfortably accommodate 50-watt lights. This is because this circuit breaker has the capacity to supply a maximum of 1600 watts. It means that you can have up to ten 50-watt lights on this circuit breaker.
The total wattage of the lights should be below 1600 watts. This is to avoid overloading the circuit breakers.
If you want to install more than 10 lights, then they should be lower in wattage or power consumption. For instance, 25-watt lights can accommodate up to 15 pieces on a 20-amp circuit breaker.
This is because 25 watts times 15 pieces = 375 watts, which is below 1600 watts.
How many watts can a 20-amp circuit breaker handle?
To know the number of lights that a breaker can accommodate, it will be prudent to find out the watts that it can handle. We can find out this by multiplying the current of the breaker and the supply voltage.
So, if you have connected the 20-amp breaker to a 120V source, its wattage will be 1200 watts.
For the 240V supply, you will have 4800 watts.
Once you know the wattage, you can go ahead to calculate the number of outlets that the circuit breaker can handle. For a 2400watts, it will accommodate 10 outlets.
You should always remember the National Electric Code regulations when it comes to deciding the number of outlets a breaker should have. It is always capped at 80% of the maximum amperage that the breaker can carry.
The above example is an exception because it is a 20-amp circuit breaker, which is capped at 10 outlets.
In addition to that, consider the 20% startup safety margin. This is vital since most electric fixtures tend to consume maximum amperage just when starting.
Calculating the number of light fixtures to add
Image source The HandyNest
Now let’s do the mathematics for the total number of fixtures to add to the 20-amp circuit breaker.
If you are using a standard light fixture whose power rating is 50-watt and is connected to a 120V source, you will fix 38 light fixtures to it.
How have we arrived at this figure? The consumption of a 50-watt light will not exceed half the amperage of the circuit breaker.
Also, keep in mind that not all bulbs are rated 50 watts. This means that the number will vary depending on the wattage of the light.
We can find out the exact number by dividing the optimum continuous load of the circuit breaker by the wattage of the light fixture. We found out that the continuous load of a circuit breaker connected to a 120V is 1920. So, we will divide 1920 by the rated wattage.
Let’s use some examples:
60 watt light you will divide 1920/60=32. This means that it will be safe to install 32 light fixtures on your 20-amps circuit breaker.
Distribution of the light fixtures
Other than the number of light fixtures, you should also pay attention to how they are distributed. The distribution should be uniform so that the light is evenly distributed throughout the room.
If you have a lot of light fixtures, you can use a fan to distribute them evenly. You will want to install it in such a way that it will blow air from the center of the room towards all sides. This will help provide an even spread of light throughout your home.
In addition to having a uniform distribution, you need to also ensure that there is no dead space in the room where no lights are installed at all. If there is dead space, no light will be able to reach that area and this may cause your lighting system to break down over time.
The ideal way to do this is by using dimmers. This allows you to control the amount of light from one fixture or multiple fixtures at once so that they can be turned on and off based on your needs or moods.
How many lights per circuit?
When figuring out the number of lights to add to a circuit breaker, always consider the maximum number of lights per circuit. Going by the 80% NEC rule, you will only add up to 10 lights per circuit. This is a good rule to follow and will save you money and energy.
For example, if you have a 20-light ceiling fixture, you can install the lights in two circuits, which means that each circuit can support up to 10 fixtures.
If you have a 100-bulb chandelier, it is best to use two circuits. This will allow you to have up to 20 fixtures on each circuit.
Should I put lights and receptacles on the circuit?
Now that you know the number of light fixtures, you could be pondering the possibility of combining the lights and the fixtures on one circuit. There is no problem in adding both on a single circuit. However, before you do so, try to consider other factors and one of them being the laws governing your local area. Some areas restrict electricians from adding the two on one circuit.
It will also be wise to consider the expenses involved in adding the two.
Now that you know the number of lights to add to a 20-amp circuit breaker, the next thing to think of is looking at the rating of each bulb. Be careful to avoid overloading the circuit. And finally, buy quality circuit breakers from reliable sources.
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