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How Many Amps Does A Bathroom Exhaust Fan Use?

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Last updated on August 14th, 2022 at 01:28 pm

Using a bathroom exhaust fan is quite handy as it reduces odor in the bathroom, removes moisture from the bathroom, and can help with cleaning out dangerous fumes associated with cleaning agents.

However, with the rising need to conserve energy, keep our planet clean, and consider the rise in the cost of energy, we must notice the electricity our appliances consume.

An amp is a unit of measurement for electrical currents and can be calculated by dividing watts by volts. So, how many amps does a bathroom exhaust fan use?

A regular bathroom fan used in a residential area uses about 0.3 amperes. A typical exhaust fan is likely to consume about 30 to 50 watts. So, if you’re only turning on your bathroom exhaust fan when it’s needed, it will most likely cost you very little. Bathroom exhaust fans draw as little as 0.005 amps per CFM with modern designs.

Does A Bathroom Exhaust Fan Need A Dedicated Circuit?

The bathroom exhaust fan does not always need a dedicated circuit. Also, if it is a small home exhaust fan, it can be combined with lights without any qualms. The reason is that exhaust fans require very little power compared with other appliances around the house.

Sometimes, the exhaust fan is wired together with lights, and once the lights are switched on, the exhaust fan comes on as well. However, it is not a requirement. The fan and light can have different switches and operate seamlessly.

Nevertheless, if a bathroom exhaust fan has a built-in heater, it needs a 20-amp circuit. This is because it consumes extra power, and putting it on the same circuit as other appliances may not be completely safe. It is known as a dedicated circuit because it is meant to be used by only one appliance.

Home appliances like wall-heaters, heat lamps, and other devices for heating the home, especially the built-in appliances, also have dedicated circuits.

How Many Amps Does An Exhaust Fan Have?

The amperage of a bathroom fan is usually calculated by how much air the fan moves with and how much power the fan consumes in the process. The higher, the better.

Most smaller home exhaust fans have about 1.4 and larger ones about 2.8, although the numbers vary. However, most of the time, the energy efficiency of exhaust fans is measured in watts or per CFM, so smaller fans have about 89 cfm while larger ones have about 90-500 CFM.

Generally, bathroom exhaust fans use a 15-amp circuit breaker. Although for exhaust fans with heaters, a 20-amp circuit breaker is preferable as it consumes more power. The usual requirement for a regular exhaust fan is 1 watt per 3 CFM or 5 CFM (Cubic Feet Per Minute).

In that case, you will draw about 50 watts or even less, maybe about 30.  As such, if your exhaust is a regular modern fan, then it is likely to consume the same quantity of power as a 40-amp light bulb, all things being equal.

Can Bathroom Fan Be On 15-amp or 20-amp Circuit?

A bathroom fan consumes about 0.3 amps or even less, so putting it on a 15-amp circuit is functional and will not present any safety issues. In addition, most bathroom ventilation or exhaust fans use the 15-amp Circuit, and the systems are durable and long-lasting, so it is not a bad idea to put the bathroom fan on a 15-amp circuit.

However, according to the NEC guidelines, the bathroom should have a separate circuit for lighting and a bathroom exhaust fan. So if the circuit is only for lighting, it can be a 15-amp circuit. But if it is also going to have the bathroom fan, it is better if it is a 20-amp circuit.

Additionally, one has to consider the additional power used if the fan has a heater. If the fan has a heater then, it will draw more power. As such, a 20-amp circuit will be ideal. In comparison, a 15-amp circuit will be too small, especially if the lighting is on the circuit.

Generally, a bathroom fan should be on a 20-amp circuit. It is safer, and you can install the lighting, the receptacles, and the bathroom fan on a singer 20-amp circuit, although it must be serving the bathroom alone and not any other rooms.

What Size Cable Do I Need For A Bathroom Extractor Fan?

While installing a bathroom extractor fan, the size is quite important. It’s essential so you don’t end up with a tiny cable that cannot withstand the heat or one that is too large and is difficult to work with.

For a bathroom extractor fan, the minimum cable size is 1.0mm. However, suppose you’re looking for something more significant. In that case, it is better to use the 1.55mm cable, primarily if the extractor fan will be operated by an independent light switch, meaning the light switch will not turn it on.

Any cable larger than 1.55mm is unnecessarily large and will be more challenging to work with per installation and repair. However, you can still use a larger cable than the 1.55mm if you wish to.

Can Extractor Fan Be Wired To Lighting Circuit?

More often than not, extractor fans derive power from a lighting circuit. And since the light switch turns on the fan, it cannot be operated by or connected to circuits. So regardless of the extractor you have, you can still have it in your lighting circuit. However, there are certain things that you should take into account.

For instance, you should know how many light fixtures are and their power beforehand. This is vital to know all the loads on the circuit.

The load can be calculated by putting together all the loads on the circuit. If it’s a lot, you will need to upgrade the extractor. However, it is best to have an electrician look at it safely.

Also, you should consider the size of the extractor. If it is a small-sized bathroom extractor, then wiring it to the lighting circuit shouldn’t be a problem.

On the other hand, if the extractor is enormous, like a large industrial extractor, for instance, that could not be entirely ideal, in which case you should call an electrician.


It is essential to know the quantity of power that home appliances require and consume, not just because of the cost but also for safety reasons. So, the bathroom fan uses about 0.3 amps or more depending on the fan itself, the make, and whether it has a built-in heater or not. Also, a bathroom exhaust fan needs a dedicated circuit.

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