This is a simple question that can be very confusing. There is no definitive answer, as the number of lights on a 15-amp circuit will vary depending on the lightbulb type, the bulb’s wattage, and the circuit breaker type.
While updating the lighting system in one’s home, one of the first thoughts should be the number of lights the circuit can handle. Each household or building may have a different circuit amperage, but the most common is the 15-amp circuit. In this article, I will explain how many light bulbs can fit in a 15-amp circuit depending on the bulb type.
If you are using incandescent light bulbs, you can use 14 up to 57 of them. If you use CFL bulbs, you can place 34 up to 130, whereas installing 84 up to 192 LED bulbs. Those numbers are for the minimum and maximum wattages. Incandescent light bulbs use a maximum of 100W, LED lights use up to 17W, and CFL lights use up to 42W.
Lights on a 15 Amp Circuit Calculator
The range of bulbs you can place in a 15-amp circuit is between and bulbs.
Here is a table of the number of lightbulbs you can place on a 15-amp, 120-volt circuit based on wattage:
| Wattage | Number of Bulbs |
|---|---|
| 60 watts | 24 bulbs |
| 40 watts | 36 bulbs |
| 25 watts | 57 bulbs |
| 15 watts | 96 bulbs |
I’ll go into more detail below.
An Introduction – The Math
All circuits are designed to withstand a specific amount of current, sometimes more than what they are made for (i.e., a 15-amp circuit can handle more than 15 amps of current).
However, the electric circuit breakers limit the power capacity of the circuit to protect it from unexpected power surges. Thus, to avoid tripping the breaker, one should follow the “80% Rule”.
By multiplying 15 amps by 80%, we get 12 amps, which is the maximum capacity of the 15 amp circuit.
Incandescent vs CFL vs LED Bulbs
The most common types of bulbs are incandescent, CFL, and LED.
The main difference between the three is the thermal energy. LED light bulbs do not produce heat, requiring much less energy to produce the same amount of lighting as an incandescent and CFL bulb.
Thus, if you plan to install many light bulbs to a 15 amp circuit breaker, your best option is to install LED bulbs.
How Many Light Bulbs Can One Install on a 15 Amp Circuit
Each of the three categories offers a different amount of efficiency.
That means that 15 amps circuits and 15 amps circuit breakers can handle a different number of incandescent, LED, and CFL bulbs.
For the calculations, I will use each bulb type’s maximum and minimum wattage. Thus, you will know the range of light bulbs you can install in a 15 amps circuit.
Let’s do the math.
Incandescent Bulbs
As mentioned above, incandescent light bulbs require much more energy than other bulbs. That means that you can install fewer incandescent bulbs than CFL and LED.
- The minimum wattage of incandescent bulbs is 25W.
The maximum amperage that flows through the circuit is 12 amps (according to the 80% rule). Thus, by doing the math, we get: Wattage equals Voltage times Amperage:
P = V * I = 120V * 12A = 1440W
Now, to calculate how many bulbs you will be using, I need to divide the wattage of the circuit by the wattage of a single light bulb:
1440W / 25W = 57.6 light bulbs
Since you cannot place 0.6 bulbs, I will round it up to 57.
- The maximum wattage is 100W
The maximum amperage will remain the same, i.e., 12 amps. Thus, the wattage of the circuit will also remain the same, i.e., 1440W.
By dividing the wattage of the circuit by the wattage of a single light bulb, I get:
1440W / 100W = 14.4 light bulbs
Since you cannot use 0.4 bulbs, I will round it up to 14.
Thus, the range of incandescent bulbs you can place in a 15-amp circuit will be between 14 and 57.
CFL Bulbs
CFL bulbs’ wattage ranges between 11-42W.
- The maximum wattage is 42W.
The maximum amperage of the electrical system will remain the same as the incandescent bulbs, i.e., 12 amps. Thus, the wattage of the circuit will also remain the same, i.e., 1440W.
By dividing the wattage of the circuit by the wattage of a single light bulb, I get:
1440W / 42W = 34.28 light bulbs
Since you cannot use 0.28 bulbs, I will round it up to 34.
- The minimum wattage is 11W.
By dividing the wattage of the circuit by the wattage of a single light bulb, I get:
1440W / 11W = 130.9 light bulbs
Since you cannot use 0.9 bulbs, I will round it up to 130.
Thus, the range of incandescent bulbs you can place in a 15-amp circuit will be between 34 and 130.
LED Bulbs
LED bulbs’ wattage differs between 7.5W and 17W.
- I will begin with the maximum wattage, which is 17W.
The maximum amperage of the electrical system will remain the same as the incandescent and CFL bulbs, i.e., 12 amps. Thus, the wattage of the circuit will also remain the same, i.e., 1440W.
By dividing the wattage of the circuit by the wattage of a single light bulb, I get:
1440W / 17W = 84.7 light bulbs
Since you cannot place 0.7 bulbs, I will round it up to 84.
- For the minimum wattage, which is 7.5W
By dividing the wattage of the circuit by the wattage of a single light bulb, I get:
1440W / 7.5W = 192 light bulbs
Thus, the range of incandescent bulbs you can place in a 15-amp circuit will be between 84-192 bulbs.
Take a look at some of our related articles below.
- How to test a fluorescent light bulb with a multimeter
- How to wire a light bulb holder
- Do LED light strips use a lot of electricity
Video References
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