- General Formula
If you’re planning to install recessed lights in your home, you might wonder how many you can have on a standard 15-amp circuit.
This article will help determine how many recessed lights you can run concurrently on a 15-amp circuit without overloading it. By doing a little math, you can easily calculate the total number of recessed lights you can use.
The maximum power of a 15-amp circuit on a 120V supply is 1,800 watts. However, it is recommended that you use no more than 80% of that, which makes it 1,440 watts. So you can use recessed lights up to a total power of 1,440 watts. If each one is 60 watts, you can have up to 24 on the same circuit at the same time.
The actual limit thus depends on the exact wattage of each light. If you have low wattage or more power-efficient recessed lights, such as LED ones, you can install more (144 if they are 10 watts each). If you have other non-LED recessed lights that require higher power, you will only be able to install a few numbers.
I will also tell you how this limit is affected if you have mixed recessed lights or if you use LED ones and answer other related questions.
Here is the calculation to determine how many recessed lights you can use on a 15-amp circuit.
Recessed lights are normally connected to a 15-amp circuit. A 15-amp circuit breaker might allow you to install as many as 30 lights and as few as five. But the actual number depends on the total power of your recessed lights.
Here is a chart that shows the maximum number of recessed lights that can be safely run on a 15-amp circuit based on the wattage of the light bulbs:
|Light Bulb Wattage||Maximum Number of Recessed Lights|
Equal Power Rating
So, to determine how many recessed lights you can install, firstly, you must identify the power rating for each one. Then you need to add them to find the total power consumption. In this calculation, we will assume they are equal at 60 watts each.
A 15-amp circuit can theoretically handle 1,800 watts in a 120-volt system (120 volts x 15 amps = 1800 watts).
Since a circuit’s safe, usable limit is 80%, the power consumption should be no more than 1,440 watts (1800 x 80 / 100 = 1440 watts).
The total number of recessed lights we can use is 1440 / 60 = 24 lights.
As you can see, assuming all the recessed lights have the same wattage, the formula is simple:
We can use a number of recessed lights on a 15-amp circuit (at 120V) = 1440 / wattage of each one (if they are all equal).
Usually, to run a single recessed light, it will require a minimum of 60 watts. So, using the above calculation, you can power up to 24 recessed lights on a single 15-amp circuit.
However, suppose you are using other appliances along with it, such as fans or other electronic appliances. In that case, you will have to calculate the total wattage of all the appliances in the circuit to prevent overload.
Mixed Recessed Lights
What if you have mixed-wattage recessed lights, i.e., the power ratings differ?
You may not have all the lights with the same wattage in your house. You can have mixed wattage lighting on the same circuit as long as the 12A current limit of the circuit is not exceeded (or the maximum power of the circuit, which is 1,440 watts). This type of setup requires a different way of doing the calculation.
You will need to collect information for each recessed light on the same circuit. Thus, firstly you must find out the watts of each light on it, then work out the total by combining all the watts.
Remember, the total amperage used by the recessed light must not exceed the limit of 12 amps for a 15-amp circuit.
Example: Suppose you have 4×60-watt recessed lights in your house and 5×75-watt lights on the same 15-amp circuit. In this case, your calculation will look like this:
1×60-watts = 60 / 120 = 0.5 amps, so 4 lights will use 4×0.5 = 2 amps
1×75 watt = 75 / 120 = 0.625 amps, so 5 lights will use 5×0.625 = 3.125 amps
To get the total, we have to sum the current for all the lights:
Total amps = 2 amps + 3.125 amps = 5.125 amps
The result for total computation (5.125 amps) is well below the limit of 12 amps allowed on the circuit.
In short, if the wattage of the recessed lights is not equal, then you can use as many as you need, as long as the total power consumption does not exceed 1,440 watts or the current does not exceed 12 amps.
LED Recessed Lights
If you use LED recessed lights, they will likely be more efficient and have a much lower power rating.
Suppose each LED recessed light is rated at 10 watts. On a 15-amp circuit, you can use roughly 144 of them.
The calculation here is 1440 / 10 = 144 recessed lights.
Whether you use mixed wattage or type of recessed lights, you can easily work out how many you can use on a 15-amp circuit by using the general formula.
I will show you two ways how you can determine the amps of any light bulb. Using one of these methods and the 80% circuit breaker rule, you can easily determine how many lights are allowed on the circuit.
The first method you can use is the method we have mentioned before to work out the current of each light, which is: current (in amps) = power (in watts) / voltage (in volts).
However, you can use a multimeter to know the exact current draw. This will tell the multimeter act amps of the circuit where you are connecting the recessed lights.
The second method is to work out the total power consumption of all the lights on the circuit. You can do this manually by adding the power ratings of each recessed light or by using the multi-meter to see the power multimeter of the circuit to see how many more you can add.
How many lights of 75 watts each can run on a 15-amp circuit?
Using the formula above for a 120-volt circuit and applying the same limitation rule of 80%, you can use up to 19 recessed light bulbs. I also gave the general formulas above for X watts and mixed wattages.
How many watts does a recessed light need to operate?
To operate a single (non-LED) recessed light, you will typically require a minimum of 60 watts. It mostly depends on the type of light you are using. LED recessed lights operate on much lower watts of around 10 watts.
Can we put a ceiling fan on the same circuit as a lighting circuit?
Yes, you can put lighting and ceiling fans on the same circuit if you don’t exceed the limit of total amperage (12 amps) or power consumption (1,440 watts). However, if you want to operate more recessed lights, then it is recommended that you give both types of appliances separate circuits.
How many amps does a recessed light draw?
The amount of amps a recessed light can draw depends on the bulb used. Generally, the size and shape of a recessed light are designed with a letter or number indicated on them, such as PAR 39 or A19.
Usually, LED recessed lights draw between 3 and 10 amps at most. But remember that every light has a different size and function, so it may vary from one light bulb to another.
To determine the exact amperage of the recessed lights with their size and features, consult the bulb manufacturer for additional information.
Take a look at some of our related articles below.
- How to wire LED lights to 120v
- How to wire a light bulb holder
- How many lights can be on a 15-amp circuit
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