Ceiling fans and lights are the most common electric devices in every room of a house, office or industries. The quantity of fan increases with the size of the space it is going to cover. So, getting to know how many fans you can connect together in a space under a circuit breaker is important. Let’s take 20 Amp for example, how many fans can you run on it?
In a 20 Amp circuit you can connect a maximum number 25 fans. But for safety purpose it is recommended to connect about 20 ceiling fans under a 20 Amp circuit breaker.
The recommended number is quite low than the maximum number. You must be thinking what is the reason behind this. Yes, there are some basic electrical rules and reasons behind the fact. I am going to cover all these facts in this article. Hopefully you are going to love what you are going to learn in a while.
How Many Amps Does A Typical Ceiling Fan Draws?
A standard ceiling fan consumes about 80 to 90 watts which results in a drawing of 0.67 to 0.75 Amperes of current at the least.
I am saying ‘at the least’ because I am assuming a unity power factor while calculating the values. Power factor may vary and you should note that the current consumption will increase with the fall of power factor.
Now many of you may ask what is power factor? Well power factor is a ratio of the real power (watt) to apparent power (volt-ampere). A power factor is good when it is close to 1 (unity).
What Does A 20 Amp Circuit Means?
A 20 Amp circuit indicates the maximum rated current of a circuit breaker that is governing the current flow of the circuit.
For a 120-volt system, a 20 Amp circuit has a maximum wattage of 2400 watts. It is recommended to use 80 percent of the maximum limit of a breaker. So, for a 20 amp circuit you should connect around 1800 watts of devices.
How Many Ceiling Fan Can You Run On A 20 Amp Circuit?
In short, you can run a maximum of 27 fans where the fans have a wattage of 80-90 watts and a unity power factor for the power supply. In practical the power factor is not unity, but close to unity. In such case, in a 20-amp circuit 25 fans fit well.
While designing a circuit, the amount of load to be handled by a circuit breaker is set at 80% of the rated capacity of the breaker.
So, you may run 25 fans in a 20-amp circuit but you should actually connect a total of not more than 20 fans for such a circuit.
I am going to break down the calculations, otherwise I am sure you are going through a tough time trying to understand how I am doing things here.
First of all, you need to identify some important factors of the circuit and power supply. Like:
- The rated voltage
- Rated current
- Power factor
- Wattage of a ceiling fan
- Safety factor: use 80% of the load capacity of the breaker
Let’s take the rated voltage of America, that is 120 Volts. The rated current is 20 Amp, according to the topic of the article. Power factor is a varying factor.
The average power factor in America is said to be in between 0.85 to 0.95. So, let’s take 0.90 as the power factor for our calculation. And the wattage of a ceiling fan is 85 watts. All set, now move to the calculation.
The first thing you need to calculate is the maximum watt that the circuit breaker can handle. It is going to be:
Max Power of Circuit Breaker= Voltage * Current * Power Factor
= 120 * 20 * 0.90
= 2160 Watts
So, the maximum number of fans that can be connected= 2160/85
= 25 fans
80% of the max power of CB= 2160 * 80%
= 1728 Watts
So, the number of fans you should connect = 1728/85
= 20 fans
This is how you can calculate the number of ceiling fans for a given rated current of a circuit breaker. This a very basic electrical calculation that can be used in many other calculations.
How Many Ceiling Lights Can Be On A 20 Amps Circuit?
Lights can have different wattage. So, the number of lights on a 20 amps circuit depend on the wattage of the lights used. If you are using 100 watts bulb you will be able to use about 17 bulbs following the rules I stated above.
The number of lights that can be used will increase if the wattage of the bulbs is reduced. That means if you use 60-watt bulbs, the total number you can use will be about 28 bulbs. After learning the calculations, I think you are qualified to carry out these all by your own.
How Many Ceiling Fans Can You Put On A Circuit?
It is quite similar to the main topic of our article. But the difference is that the circuit amperage is variable. So, the answer will be ambiguous. The number of ceiling fans you can put on a circuit depends on the amperage of the circuit. The amperage depends on the circuit breaker and wirings.
To elaborate, you can think of a 30 amp circuit now. How many ceiling fan can you connect here? Well, following the calculations the number of ceiling fans will be about 30. There you see, as the amperage of the circuit increases, the number of possible fans also increases.
If we are talking about a 10 amp circuit. The number of fans will be about 10 only. Thus the number of fans decreases with the decrease of amperage of the circuit.
How Much Power Can A 20 Amp Circuit Handle?
Power is the product of current and voltage. So, a 20 amp circuit can handle a total power of 2400 VA, which is 2160 Watts in a 120 Volts system. Are you puzzled again by this calculation? Okay let me give a brief on this.
The total power can be found by multiplying the current and voltage of the circuit. The unit of this total power is Volt-Ampere (VA). To find the wattage which is actually known as Real Power, you have to multiply the total power by the power factor which we assumed to be 0.9.
So, Real Power= 2400*0.9 = 2160 Watts.
This is the theoretical amount the circuit can handle if it is wired properly. You should know which wire to use for a specific circuit. Even while wiring a fan you must know what gauge wire for a ceiling fan must be used to ensure its efficiency and safety.
While wiring you will face more curious things. You might then ask me where does the blue wire go in a ceiling fan? We will be talking about them another day.
I hope you have enjoyed and learnt quite a lot from this article. Especially, the ones who are new to electrical will find this article really helpful. The calculations are very basic and important in almost all kinds of electrical applications. So, try to understand the topics well and practice. Have a great day!