Home circuits are purposefully created to work with a specific electrical load while maintaining predetermined safety margins. Make sure not to overload the circuit if you intend to add new lighting fixtures to your house. So how do you calculate how many lights you can run on a 15-Amp circuit?
Depending on the wattage of the lights, a 15-Amp circuit can support a certain number of lights. The total amperage drawn by the circuit’s lights cannot be greater than 80% of the rating of the circuit breaker. This will be a maximum of 12-Amps for a circuit breaker rated at 15 amps. You can connect up to 24 lights to a 15-amp breaker, assuming each light is 60 watts.
You can install up to 150 bulbs on a single circuit if you use low-wattage LED bulbs, such as a 10-watt LED bulb. Due to the inability to use any other types of bulbs without going over the 15 amp limit and tripping the circuit, we do not advise doing this. This is a good example of how well LED bulbs conserve energy, though.
Maintaining the proper load on a circuit is important for your home’s safety. In addition to being annoying, an overloaded circuit puts your home at risk of fire. It will give you the safety margins to plan to add new light fixtures to your home if you have a basic understanding of how much a circuit can handle. Let’s examine how to precisely calculate a 15-Amp circuit’s capacity.
How Much Can a 15-Amp Circuit Handle?
Your home’s electrical circuits can only support a certain amount of electrical load. A circuit is shared by outlets in a space with similar demand requirements.
Just as contractors group electrical outlets together, grouping lights in your home enables wiring on a separate circuit.
The number of lights you can run on a circuit varies by the circuit breaker’s rating, thickness or gauge of the wire used in the circuit, and the energy required by the lights.
Depending on the circuit, homebuilders will use wires of a different gauge. Electrical wire that is 14 gauge, which is thinner than the wire used for electrical outlets, is used in the lighting circuit. Typically, a thicker copper wire, between 12 and 10, is used in circuits with a 20-Amp breaker rating.
A wire will become hot when it receives an excessive amount of current or amperage. When too much current flows through a cable, thinner wires heat up more quickly.
With a few minor exceptions, the majority of local wiring codes adhere to the general principles of the NEC. The NEC states that a circuit breaker load should not exceed 80% of its capacity.
As a result, you are only permitted to have a maximum of 12-Amps flowing through the circuit at any given time on a 15-Amp circuit breaker. The number of light fixtures that can be installed on a 15-Amp circuit is not officially limited. However, you will break the wiring code if all those lights are on at once and the current is greater than 12-Amps.
Therefore, you should only add the number of light fixtures and globe wattage to the circuit that would allow you to stay under the 80% restriction if all of the lights were turned on at once.
How Many Lights Can I Put on a 15-Amp Circuit?
The number of lights that can be connected to a 15-Amp circuit is determined by the wattage of the bulbs that are used in the light fixtures, as we have already mentioned.
To figure out if you are within the 80% capacity limit of the 15-Amp circuit breaker, you will need to check the wattage of each light on the circuit and do a little math to check your limits.
How Do You Work Out Light Wattage to Amps?
The rating for circuit breakers is measured in amps, whereas the rating for lights is measured in watts. To set the circuit’s limits, you must convert the lights’ Wattage into the same unit of measurement as the circuit breaker.
Because the light wattage combines voltage and amperage, you can quickly determine this limit using a straightforward equation. If your home is different from the majority of homes, you must substitute your voltage where 120-Volts is used in the equation.
Watts are calculated using the equation Watts = Amps X Volts. Use the following equation to reverse the formula to obtain amps.
Amps = Watts / Volts
Plug the values into the equation to get the amps that a 60-Watt light bulb will consume.
Amps = 60-Watts / 120-Volts
Amps = 0.5
Our findings indicate that a 60-Watt light will use 0.5 Amps of current. To determine whether we are within the circuit breaker’s 80% capacity or whether we need to install a completely new circuit to add more lights to our home, we can use this calculation for each of the light circuits in our house.
To make sure we are operating within the parameters of our circuit, let’s develop a few more examples of this calculation in use.
How Many 75-Watt Lights Can Be on a 15 Amp Circuit?
How many of these 75-Watt lights can you install on your 15-Amp circuit if you want to install them on all of your light fixtures while still staying within the 80% restriction?
Amps = 75-Watts / 120-Volts
Amps = 0.625
0.625 Amps of current are required to run a 75-Watt light. We must divide the 12-Amp limit by the Amps used by the light in order to determine the maximum number of these lights that can be installed on the circuit.
12-Amps / 0.625-Amps
= 19.2 of the 75-Watt Lights
Using this formula, we can install up to 19 of the 75-Watt lights while staying within a 15-Amp circuit breaker’s 80% maximum capacity.
How Many 100-Watt Bulbs Can Be on a 15 Amp Circuit?
Using this formula, we can calculate the maximum number of 100-Watt lightbulbs that could be installed on the circuit while still adhering to the wiring code’s restrictions.
Amps = 100-Watts / 120-Volts
Amps = 0.833
A light that uses 75 Watts will use 0.625 Amps of current. We must divide the 12-Amp limit by the Amps used by the light in order to determine the maximum number of these lights that can be installed on the circuit.
12-Amps / 0.833-Amps
= 14.4 of the 100-Watt Lights
Again, according to the formula, we can only install a maximum of 14 100-Watt lights while still staying within the 80% range of a 15-Amp circuit breaker.
What If You Have Mixed Wattage Lights?
Realistically, our homes don’t all have lights with the same wattage, so you need to gather the information for each light on the circuit. You must first determine the Wattage of each light on the circuit, calculate the Amps each light consumes, and then add the Amps collectively.
The maximum 12-Amp limit for the 15-Amp circuit breaker must not be exceeded by the combined Amps used by the lights on the circuit.
For instance, your calculation would be as follows if you had two 60-watt lights, five 75-watt lights, and three 100-watt lights all connected to the same 15-amp circuit.
1 x 60-Watt = 0.5-Amps, so 2 lights use 2 x 0.5-Amps = 1-Amp
1 x 75-Watt = 0.625-Amps, so 5 lights use 5 x 0.625 = 3.125- Amps
1 x 100-Watt = 0.833-Amps, so 3 lights use 3 x 0.833 = 2.5-Amps
The result of adding the current drawn by all the lights is as follows.
1-Amp + 3.125-Amps + 2.5-Amps = 6.625- Amps Total
Our calculations reveal that our total of 6.625 Amps is still significantly less than the 12-Amps permitted on the circuit.
Types of Lightbulbs
1. Incandescent Light Bulb
Warm light produced by incandescent bulbs at first made them popular. Now, they are among the least expensive bulb types, which explains why some people still use them
This light’s typical wattage rating is between 40 and 100+.
However, a law passed in 2007 restricted its use as common illumination due to its energy inefficiency.
2. Halogen Light Bulb
The halogen light is an enhanced version of the incandescent bulb. This bulb uses halogen gas, which is a significant distinction from incandescent bulbs. The wattage is 90 on average.
3. Fluorescent Light Bulb
The fluorescent lamp has been widely used in workplaces, parking lots, and other settings, including residences. In addition, it uses less energy, is brighter, and has a longer lifespan than incandescent bulbs.
In particular, this bulb typically uses 8 to 30 watts of power in standard home lighting.
4. LED Light Bulb
LED (Light Emitting Diode) bulbs are now frequently used in domestic, professional, and even industrial settings. They are well-liked because of their low power consumption and long lifespan.
Its higher price compared to other bulb types is its biggest drawback. Only 6 to 20 watts may be necessary to completely illuminate your home due to its high efficiency, which uses less amperage.
Can I Go above 80%?
There is no law prohibiting you from exceeding the 80% allotment we previously discussed. If you can’t get the numbers to balance, going a few watts above it won’t be the end of the world. The goal is to keep track of what is plugged into that circuit to make sure you are not overloading it and having to deal with all of those issues.
The recommendation to adhere to the 80% rule is wise. This helps to give you a lot of flexibility when it comes to the circuit’s strength. Your electronics and lights will function normally in the event of a power surge, which won’t cause a major problem. You will appreciate the idea of having that extra leeway so you do not damage your appliances, especially as the circuit ages and loses some of its power.
What Happens If I Plug Too Much into a Circuit?
You should only connect a specific number of LED lights to a circuit for a variety of reasons. To keep your house safe and secure is the most crucial reason. There may be many problems and even a fire in your home if the circuit is overloaded. A minimum amount of power will be consumed.
There’s a possibility that the circuit will overload if you attempt to connect more lights and other devices than what’s advised to a single outlet. All of the functional appliances connected to the circuit will be turned off and stopped as a result. If you’re not careful, it might cause the circuit to overheat, start a fire, or even explode.
Conclusion: It is Easy to Determine How Many Lights You Can Run On a 15-amp Circuit
It’s a relatively easy exercise to determine how many lights you can run on a 15-amp circuit, and doing so will enable you to plan out any additions you want to make to your home’s electrical circuits.
It is always safer to use the services of an experienced electrician if you have any doubts about your calculations or how to perform any maintenance on your electrical circuits. Electricity can be dangerous, so it is not worth putting your family’s health and safety at risk in order to save a few dollars.
Can I use a lighting circuit to connect ceiling fans?
Yes, provided that the fans and bulbs don’t draw more power than the circuit’s allowed amperage. Give each fan their own breaker if you have a large following.
How Many Receptacles and Lights on a 15 Amp Circuit?
Technically, a 15 amp circuit breaker can support any number of outlets. A good rule of thumb, though, is one outlet for every 1.5 amps, up to 80% of the circuit breaker’s capacity. Therefore, we would suggest a maximum of 8 outlets for a 15 amp circuit.
How Many LED Lights Can I Plugged in Together?
Therefore, your circuit can only handle 14 incandescent light strings connected together. On the other hand, if a typical set of LED string lights consumes 10 watts, 1440/10=144. If they are LED, you can connect 144 light strings together, so there! More light than an incandescent bulb, that is.