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How Many Lights on a 15 Amp Circuit Can You Run? [Answered]

Everyone wants to see their home or office space in brighter lights. Because more light will keep your mind active and provide clear visuals.

How many lights on a 15 amp circuit can you run? 

It will be 12 amps maximum for a 15 amps circuit breaker. This 12 amp is the 80% limit of the circuit breaker.  A 15 amp breaker can support up to 36 lights if the light is 40 watts. On a single circuit, you can connect up to 150 LED lights. For that, you have to use low-wattage LED bulbs.

But that’s not all. I’ve included additional details for your convenience. To know more elaborately, stay with me and keep reading!

Things You Should Know Beforehand

Before getting into the practical part, you have to know what you are dealing with. I suggest starting with the basics first.

What is a Circuit? 

To know what a circuit is, it is a path. It allows the flow of electricity between two points. Electricity flows through a circuit breaker box and divides into a few circuits. 

A 15 amp circuit is used for running fans, lights, and clocks. It is mainly used for running small electrical machines. 

And, a 20 amp circuit is used for running irons, heaters, toasters, and hair dryers. Finally, central air conditioners require a 30 amp circuit of their own. 

Sometimes, people use their bedroom lights-outlets on the same circuit

What is the Concept of a Circuit Breaker?

A circuit breaker is designed to protect the circuits from damage. That can be generated by an electrical short circuit or overload. The circuits are protected by a breaker. Or, in old homes, it is protected by a fuse.

What Does It Mean By a Circuit Breakers Rating?

It is the standard current rating of a circuit breaker. This means it is the RMS value (value of a varying current) of current. 

That it can efficiently carry without changes due to high temperature during normal activities. The standard current is 125% of the rated current of a circuit. 

The load of the circuit breaker should not exceed 80% of its capacity. Meaning, for a 15 amp circuit, a maximum 12 amp current can flow at a time. It should not exceed more than 12 amps. 

There are no formal restrictions regarding the fitting of lights on a circuit. Still, if the lights keep functioning altogether continuously, they will exceed 12 amp. And this will violate the wiring code. 

And, the circuit overload can cause bigger accidents if anyone or anything flammable is near. 

What Does the Gauge of a Wire Mean? 

It mainly indicates the thickness of a wire. Every gauge is shown as a number. Such as, the higher the number of the gauge, the thinner the wire is. In addition, the lesser the gauge number, the thicker the wire.

The gauge/thickness of the wire depends on the type of circuit used. For a 15 amp lighting circuit, a 14 gauge electrical wire is used. It is thinner than the wire used for an electrical circuit. 

A wire will immediately heat up if you run too much current through it. And thinner wires heat up sooner than thicker wires.

I hope you now have a good realization of the concepts mentioned above. It must help you to realize the next segment easily. 

How Many Lights Can Run on a 15 Amp Circuit?

The number of lights you can use is determined by a number of factors. The thickness and gauge of the wire used, for example. Also, the circuit breakers rating, and the energy that the lights need. 

To put it another way, you must check the wattage of each light. Such that, you must determine the total amperage required by the circuit’s lights.It should not exceed 80% of the circuit’s amperage. 

It is also possible to use a 15 amp switch with 20 amp lighting circuit

It may look complicated, but don’t lose hope. Take a look at the elaborated part of the article. It will be easy for you to follow.

In this scenario, you need to use mathematics to determine your limits. You can check if you’re under the 80 percent capacity limit this way.


The rating for lights and the circuit breaker is in watts and amps respectively. This is why, firstly, you have to convert watts to amps. 

Secondly, you have to be aware of the voltage used in your home. And with this formula. 

Amp = Watts/volts

For example, the number of amps a 40 watts bulb will draw with 120 volts,

Amp = 40/120 

= 0.33 amp

This means, a 40 watts bulb draws 0.33 amp of current. Using this calculation, you can know if you are under the 80% limits.          

Finally, to know how many 40 watts lights run on a 15 amp circuit, 

divide the 12 amp with the amp the light uses. 

12 amp/0.33 amp

= 36.36 of the 40-watt lights

This means a total of 36 40-watt bulbs can run on a 15 amp circuit. By staying within the 80% limit.

With the help of the above calculation, you can determine it yourself. 

As it is related to current, make sure you wear rubber sandals. And you have dry hands while working with bulbs and circuits. Keep the sink, gas line away from electrical outlets. Take the best possible safety measures for yourself. 

Wait, don’t go yet. The article cannot be finished without suggesting the perfect circuit breaker for you. It is the best you can find, trust me! 


These circuit breakers are long-lasting, and they work great!


Question: How many lights can be run by a single switch?

Answer: The number has no limit that can be run by a switch. The load of the fixtures determines the number of lights a circuit can support. Lighting loads of up to 1400W can be connected to a standard 15A circuit. 

Question: How many amps are used by a ceiling fan? 

Answer: A ceiling fan consumes around 120 watts for each amp it draws. The lower the setting, the less amperage is used. For example, a low-speed ceiling fan consumes around 0.25 amp. And, the medium-speed and high-speed fan needs about 0.4 amp and0.6 amp respectively. 

Question: Is it possible to have bathroom lights and outlets on the same circuit?

Answer: Yes, it is possible.  But, a 20-amp circuit is required to power the outlet receptacles. The same circuit can power the full bathroom (outlets plus lighting). But there are conditions. Such as there cannot be any heaters. And the circuit serves only one bathroom and no other places.


You’ve reached the end of the article. I hope now you can determine how many lights on a 15 amp circuit can run. 

You should keep an eye on the varying factors. Such as the wattage, rating of the circuit breaker, type of circuit, and so on.