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Is Leaving a Bathroom Fan on a Fire Hazard?

Most of us believe that the longer we leave our bathroom fans on, the more moisture they will get rid of, but can an overworked bathroom fan become a fire hazard?

We tend to run our bathrooms fans and forget about them especially modern fans that run so quietly. But any electrical appliance can become a fire hazard. If your bathroom fan is poorly maintained or has some electrical issues, it can become dangerous.

What exactly is it that can make a bathroom fan a fire hazard? Is it just a bad connection, and how long can you leave one on before you risk starting a fire?

Become more informed about bathroom fans and the associated fire risks that come with them before your home faces a tragic accident.

bathroom fan fire

Can a Bathroom Fan Cause a Fire?

It’s estimated that over the last 20 years, there have been over 500 fires that were caused by bathroom exhaust fans, according to the United States CSPC (Consumer Safety Products Commission).

That’s about 25 fires a year.

While bathroom fans don’t cause as many fires as other appliances, they are still a possible threat that you shouldn’t take lightly.

How Do Bathroom Fans Become a Fire Hazard?

One possibility is when you constantly run your bathroom fan.

Overworking your fan can cause your motor to overheat, which can ignite things like hair and other debris trapped in your fan.

Your bathroom exhaust fan can also start a fire even if it’s only used occasionally.

If your fan has bad wiring, it can create sparks that can catch fire to the debris in your fan or ductwork, resulting in a fire.

A faulty motor can also cause a fire, so it pays to regularly maintain and inspect your bathroom exhaust fan.

How to Prevent a Bathroom Fan from Catching on Fire


You should inspect your bathroom fan regularly, at least once or twice a year, or whenever it’s making odd noises which should be a cause for concern.

A simple inspection involves taking off the cover and paying close attention to the fan blade’s motor and wiring.

If you notice any obvious damage, you should repair or replace that part as soon as possible.

You can also view the fan while it is running but take care not to hurt yourself and wear some eye protection.


Bathroom fans are not normally cleaned, and this allows debris to build up, which creates fuel for a possible fire.

Regularly cleaning your fan will remove this debris, so if your wiring were to spark or your motor overheats, there would be little to nothing that can catch fire.

While this preventive measure can stop a fire before it starts, it will not get rid of the root cause, like faulty wiring.

Cleaning and maintenance can also benefit your bathroom exhaust fan in other ways by allowing it to run more efficiently and reducing unwanted noises

Install a Timer Switch

If you are someone who has a hard time remembering to turn off your bathroom fan, a timer switch may be the solution for you.

The more you run your bathroom fan, the hotter the motor will get.

By installing a timer, you can have your fan set to run for half an hour or so after you shower or bathe.

This will allow the fan to do its job by removing moisture but will not overheat or overwork the motor.

With some basic electrical experience, you can install a timer switch on your own or hire a professional to do it for you.

Replacing a Bathroom Fan

If your bathroom exhaust fan is nearing the end of your lifespan or has multiple issues, your best option is to replace it.

An old fan is more likely to cause a fire because its wiring and motor are at the point where they are more likely to fail or cause sparks.

Bathroom fans usually don’t last longer than 10 years.

Recommended read: How to Maintain a Bathroom Fan

So you will spend around $50 to $200 for a new bathroom exhaust fan, but you will get a product that will last longer, run more quietly, and is less likely to start a fire.


Is it safe to leave a bathroom fan on all night?

No, there isn’t any good reason to run a bathroom fan all night long. After running the fan for 30 minutes to an hour, it will have done its job and removed the moisture from the room. So running your fan all night won’t get any more moisture out of the room but can instead cause a fire.

Can you put a smoke detector in the bathroom?

You shouldn’t put a smoke alarm inside a bathroom. The steam from the shower will give you false alarms, and the moisture will cause the smoker detector to fail. You can install a smoker detector in the hallway or just outside the bathroom to detect fires that may start in the bathroom.

Adam McCoy

Adam is an HVAC expert and the owner of Mackydo's HVAC Services with decades of experience in fixing and installing air conditioning units, furnaces, and every type of cooling and heating equipment you can think of.

Adam believes that your home is your sanctuary. He loves sharing advice based on his lifelong experience and treats every HVAC problem as if it was his own.

About Loo Academy

At Loo Academy, our mission is to offer trusted advice for everything related to bathrooms (design ideas, plumbing advice, showering & bathing tips, remodeling guides, and more) — a place where we all spend a great deal of time.

We work closely with qualified experts and follow a thorough editing and fact-checking process before publishing content.

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