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How Many Lights Can Be on a 15 Amp Circuit? – Answered

Written by Edwin Jones / Fact checked by Andrew Wright

how many lights can be on a 15 amp circuit

It is uncommon to find many lights on a single circuit in a modern home. This arrangement is employed not only for illumination but also for decoration.

If you wish to have such a setup in your home, you must know how many lights can be on a 15 amp circuit. Frankly, the answer may be dependent on the amperage of the bulbs you intend to use. Let me discuss this with you further below.

How Many Lights on 15 Amp Circuit Can Be Used?

In most cases, a 15 amp circuit breaker allows you to install as few as five or as many as 30 lights. There are no exact numbers since the amperage of your bulbs determines how many light fixtures you may install.

To determine how many lights are allowed for any installation, you must first identify the total rating a circuit can hold and know the proper computation.

However, before we get into that topic, let me first give you some ideas about the different types of bulbs.

How Much Can a 15-amp Circuit Handle?

Because a circuit breaker should only handle loads that are 80% of its capacity, your lights should not pull more than 12 amps on one circuit

\[ 15 \text{ Amps} \times 0.8 = 12 \text{ Amps} \]

To know how many light fixtures on a 15 amp circuit are possible, you need to calculate the continuous power capacity. In detail, you only need to use a simple formula, which is volts x amps = watts.

As a result, this circuit is capable of continuously supplying 1440W

\[ P(W) = U(V) \times I(A) = 120V \times 12A = 1440 \, \text{Watts} \]

Then, divide the result by the bulb wattage to get the number of bulbs. For example, if you’re using just 150W, 120V light bulbs, you can install up to 9 of them.

\[ \frac{1440 \, \text{W}}{150 \, \text{W}} = 9.6 \]

Similarly, this formula can be used for a 20 amp circuit or any circuit requiring a load calculation. The same goes for determining the number of high or low-voltage lights per circuit.

Related: Amount of Lights You Can Put on a 20-Amp Circuit Breaker.

How Do You Work Out Light Wattage to Amps?

In general, there are three ways to determine the amps of a lighting bulb. Using any of these methods as well as the 80% circuit breaker rule will help you determine how many light fixtures are allowed on the same circuit.

The first way is to use the formula Amps=Wattage/Volts, as we mentioned above.

The second and simplest method is to use an online conversion tool to convert light wattage to amps. All you have to do is enter the wattage and voltage ratings, and the result will be displayed instantly.

The third method is using a device such as a multimeter to determine the amps of a circuit where your bulb is connected. This tool can be used to read not just the amperage but also the resistance and voltage ratings.

However, checking the amps using a multimeter is a bit complicated, since you must carefully set up the tool according to the rating you need to measure to avoid blowing the multimeter fuse.



Types of Lightbulbs

  • Incandescent Light Bulb

In the beginning, incandescent bulbs were popular because they created warm light. Now, they are among the least expensive bulb types, which explains why some people still use them

The normal rating of this bulb ranges from 40 to 100+ watts.

However, because it is inefficient in terms of energy, a law passed in 2007 limited its use as common illumination.

  • Halogen Light Bulb

The halogen bulb is an improved version of the incandescent light. The major difference between this bulb and incandescent ones is that it uses halogen gas. It has an average wattage of 90.

  • Fluorescent Light Bulb

The fluorescent lamp has been widely utilized in offices, parking lots, and other establishments, including the home. It is also more energy efficient, brighter, and lasts longer than incandescent bulbs.

Specifically, the usual wattage of this bulb in standard house lighting is 8 to 30 watts.

  • LED Light Bulb

LED (Light Emitting Diode) bulbs are now widely utilized in the home, commercial, and even industrial spaces. They are popular because of their low power consumption and long life.

The biggest disadvantage of this type is that it is more expensive than other types of bulbs. Due to its high efficiency, it requires less amperage, and you might only need 6 to 20 watts to illuminate your home completely.

What if You Have Mixed Wattage Lights?

You can use mixed wattage lighting on one switch or circuit as long as it doesn’t exceed the maximum power rating of the circuit. However, this setup is not always recommended.

Mixing LED Christmas lights with incandescent bulbs, for example, may confuse the circuit’s energy distribution and create fire hazards, especially if the incandescent bulbs get hot enough to burn the LEDs.

How Many 75-Watt Lights can be on a 15 Amp Circuit?

Using the formula above and a 120V circuit, including the 80% limitation, you can use up to 19 light bulbs.

How Many 100-Watt Bulbs can be on a 15 Amp Circuit?

If the circuit is only rated at 15 amp and the lights need a 120V supply, you can use up to 14 pieces of 100 watt light bulbs.

Can I put ceiling fans on a lighting circuit?

Yes, you can, as long as the fans and the bulbs don’t exceed the amperage rating of the circuit. If you have many fans, it is better just to give them their own breaker.


In general, the circuit installation for lights and outlets is nearly the same. You must examine the overall loads and perform simple electrical computations for both fixtures.

Aside from calculating how many lights can be on a 15 amp circuit, there is one more thing to consider. Suppose you can install thirty 12 watt led lights on one line; in this case, if the circuit has problems, all your bulbs may be out of order at the same time.

As a result, splitting your various lights into separate rooms or areas may be a good idea.

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