Can Electric Fans Be Left On 24 Hours A Day?

Electric fans are pretty simple – that part is true. But can electric fans be left on 24 hours a day? And what about other questions you may have?

In this article you’ll learn:

  • If it’s ok (and safe) to run an electric fan all day and night.
  • Electric fan electricity use and cost.
  • Other related things you’ll want to know.

Can I run a fan 24 7 and overnight?

can I run a fan 24 7 section image

Yes, for nearly all household electric fans you can run them 24 hours a day, 7 days a week. Electric fans are one of the most reliable (and affordable) electric appliances around.

To summarize, here are the basics to know before I go into more detail later:

  • You can run a fan 24 7 but should not leave fans that appear to have problems or look worn-out or suspicious running unattended while you’re away.
  • If you’re away from home, leaving the fan running won’t help you stay cool unless it’s ventilating hot air to the outside. Fans work by blowing air to remove heat from your body, giving the sensation of cooling (or can be used to blow or pull hot air indoors to somewhere else).
  • I don’t recommend leaving fans running for long periods of time while you’re gone (for a whole day or days at a time). While it is true that electric fans are generally super reliable, as with all electric appliances, it’s always best to be safe and turn them off while you’re gone for some time.
  • Fans should be plugged into a properly fused or protected electrical source. (For most homes or buildings this is already covered as North America and other major countries require this due to their electrical codes). Remember that it always pays to be safe!

There’s some other helpful questions & answers I’ll cover below as well.

Are electric fans safe to leave on all night?

electrica fan running overnight in bedroom man sleeping graphic image

Do you enjoy using your electric fan for white noise to help you sleep, stay cool, and keep your electric bill down? Electric fans can be great for sleeping at night for all three reasons!

The great news is that most standard electric fans are safe to leave on all night. There are also some good benefits to doing so if you do.

Typical electric fans (like you’ll buy at a store, such as box fans, tower fans, and pedestal or tabletop fans) are pretty safe and nearly always very reliable. Electric fans like this do not cause any health issues and do not normally cause any potential electrical problems.

Here’s a list of reasons they’re good for running all night:

  • Some fans (especially box fans) create a soothing white noise that helps to mask sound and also induces relaxation and sleep. Many people really enjoy the “white noise” some fans produce for this reason as it helps them sleep better.
  • Save on home cooling costs: electric fans use only a fraction of what a small window air conditioner uses, for example. (Say 45 watts vs 500 watts or more) That means you’ll definitely have a more affordable electric bill.
  • The gentle humming and/or white noise sound of a fan can help train your mind & body to become accustomed to sleep time. It’s a healthy habit, much like when you have a regular bedtime routine.

That being said, when running a fan all the time you’ll want to be smart & safe about it. What do I mean by that? Read on to learn more…

Can electric fans catch fire?

Example of electric fan motor and AC 60Hz power graph

Example of a typical electric fan motor – in this case for a ceiling fan. Shown here is a very common alternating current (AC) powered motor with wire windings (called the stator) used to create magnetic fields that turn the central rotating portion (the rotor). This turns the fan blades that blow air for cooling you off.

Fans are generally very safe and can run for years. Most use a simple alternating current (AC) motor based on tightly wound wire sections and a central rotating assembly called the rotor. However, just like any other electrical design, they can have problems in some cases:

  • Motors have brushes (electrically conductive contacts) that are subject to wear and eventually wear out after a long time of use.
  • Defects can happen, either from the factory or over time.
  • If the motor or some other problem arises, the electrical current can increase a lot, causing it to get hot.

The short answer is that electric fans can catch on fire but it’s highly unlikely. Unlike other appliances, they do not normally get very warm or draw large amounts of electrical current (amps).

That’s in stark contrast to other appliances like electric heaters or hair curling irons that get very hot and use a ton of electricity. Those types of appliances are far more likely to catch on fire if a problem occurs (or to catch nearby materials on fire too).

NOTE: One very important thing to understand is that fans often don’t have a fuse or circuit protection built in. You’ll want to use a protected outlet or an outlet strip with a circuit breaker or fused protection. That way if something unusual happens the fan’s power will be shut off when the current drawn increases too much.

Circuit breakers and fuses protect you & your home when an excessive amount of amperage begins to be drawn. The circuit breaker will “trip” (open the circuit) or a fuse will blow – in both cases this interrupts power until you reset them.

Should you leave a fan on all day?

diagram showing how electric fans cool you

Leaving a fan on all day can be helpful under a few circumstances, but isn’t always a good idea. Fans cool you by moving air across you, removing heat as they do. This is the process of convection cooling.

You may find it helpful to leave a fan on all day if:

  • You’re present where the fan or fans are used and want to be cooled off (in other words, you’re close enough to them for the air to move across you and help keep you cool.
  • You’re using fans to move hot air out of a room or building. In that case, fans definitely are really helpful as they help cool the room. That isn’t normally the case.

Fans in a closed room (or room with windows open, but without the fan blowing out hot air) aren’t helpful aside from cooling you off while you’re there. It’s a bit of a waste to leave them running all the time if you’re not around.

In some cases, (for example, warehouses, storage facilities, etc) a fan is positioned to pull hot air build up out of the building and force it outside, usually with one or more second windows open to draw in cooler air. That’s an example of when it’s good to leave a fan running all the time (or using a timer as needed).

As I mentioned earlier, if you’re not going to be home it’s generally a good idea to turn off your fans as while they’re generally very reliable and safe, it’s better to be safe than sorry.

Do fans use a lot of electricity? How many watts does an electric fan use?

electric fan vs AC power use comparison graph

This graph shows a comparison of examples of both an electric fan and a small window air conditioner. Electric fans use a lot less electricity!

Electric fans vary in how much electricity they use based on the fan’s motor size, speed setting, and type of fan. Generally speaking, the most common electric fans use from about 25 watts to as high as 85 watts or so.

Fan Speed/Mode Typical Power Use
Sleep mode/ultra-low 5W-15W
Low 25W-35W
Medium 35W-55W
High 55W-65W, ~85W

As a general rule, you can expect small or medium-sized fans to use about 35W on low speed, 55 watts on medium speed, and around 65 watts on high. This also applies to standard ceiling fans as well.

Some electric fans like tower fans may use a special design for allowing more fan speeds and very quiet operation. These range from about 15W to about 50W or so. They often use pulse-width modulation (PWM) electronics to control the motor speed unlike the traditional simple motor of regular fans.

One thing is for sure: they use much lower wattage than air conditioners.  Somewhere around 1/10th of the power that AC uses. (Air conditioners use around 500W or more due to the power required to drive the refrigerant compressor and coolant)

How much electricity does a fan use overnight?

You can find the amount of electricity a fan uses by multiplying the power used (in watts) times the number of hours you run the fan. These units, called Kilowatt-hours, are units of power use measurement that your power company uses to determine how much to charge you every month. A Kilowatt is just 1,000 watts (“kilo” is used to denote one thousand).

Let’s use an example to figure out how much electricity a fan uses overnight. We’ll use the following numbers:

  • Our example fan is using 50W of power (set to medium, for example).
  • We use the fan overnight for 9 hours.

We need to use the wattage used in units of kilowatts. To do so, just divide the power by 1,000. So 50W/1,000 = .050 kilowatts.

This would be 0.050W x 9 hours = 0.45 KwH (KiloWatt-hours).

How much electricity does an electric fan use in a month?

Likewise, we can find out how much electricity an electric fan uses in a month. We’ll use these numbers:

  • 50 watts power usage for our electric fan.
  • We use the day for 30 days, 24 hours each day.

This means the power use in one month is .050 x (24 x 30) = 36 kiloWatt-hours (KWh).

Do ceiling fans use a lot of electricity?

Ceiling fan VS AC comparison graph with energy use measurements in Watts

Ceiling fans, like other electric fans, use a fairly small amount of electricity. Here you can see a graph comparing the power use I measured for a ceiling fan vs that of a small window air conditioner.

If you’re happy using a ceiling fan, don’t worry! The great news is that ceiling fans use an amount of electricity that’s more or less the same as a box fan or other electric fans. Ceiling fans use somewhere around 15W, 45W, and 50 to 65W for low, medium, and high speeds respectively.

(Note that this not counting power that light bulbs may draw). Of course, just like with other fans it varies by the size and design of the fan.

How much does it cost to run an electric fan?

how much does it cost to run an electric fan section image

It’s not hard to figure out how much an electric fan uses and estimate how much the electricity will cost us.

To do that we need to come up with some simple estimated numbers and also we need to know about how much our electrical power company charges. Power companies bill the power you use with a rate called cents per KiloWatt-hour. We’ll use Kilowatt-hours again as we did in previous examples.

Figuring out electric fan energy costs

Let’s take an example based on the way most people would a fan. Let’s use the following numbers:

  • Fan speed & power use (estimates): 9 hours on low (overnight) at 30W, and 15 hours (during the day) on medium at 50W, for a total of 24 hours per day.
  • 30 days in our example month.
  • Georgia, USA average electricity cost: $0.1101 per Kilowatt-hour (kWh).

Based on this, here’s a table showing how much it costs:

Electric fan electricity cost table

Time Cost
17 hours (use in one day) $0.085
1 week $0.59
1 month $2.54
1 year (365 days) $30.94

As you can see it costs very little to use yours 24 / 7 – even all year! That of course would go up a little bit if it’s left running on the highest speed but not a huge difference.

Summary + more great articles

In summary:

  • You can safely run an electric fan (including all night), but it’s not recommended while you’re gone for long periods of time. Fans are generally very reliable but it’s a safe practice to turn off electrical appliances while they’re unattended for long periods of time.
  • Electric fans (including ceiling fans) use a fairly small amount of power and are pretty cheap cost wise.
  • Using fans such as box fans at night can be very helpful for white noise to allow you to sleep better.
  • Leaving a fan running 24 / 7 is generally ok, but (1) they should be used with some type of circuit protected power source, and (2) unless using a fan to remove warm air, leaving a fan running all the time isn’t useful unless you’re there for it to cool you.

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