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What Size Breaker for a 40 Gallon Electric Water Heater? [Calculated]

A breaker is an important tool for any circuit. It protects an appliance, whenever there’s an overload, by shutting off immediately.

Since the water heater is very electricity-intensive, it needs to be paired with the right breaker! 

The question is, what size breaker for a 40-gallon electric water heater do you need?

Generally, for a 40-gallon electric heater, you’d need a 30A double pole breaker. Those should be paired with 10-2 non-metallic cables. However, make sure that you have a 240 volt dedicated circuit for your water heater. There should be no other appliance connected to it. 

You might wonder how to choose the right breaker for you? And that’s where we come in! Keep reading to find out more!

Factors that Determine the Right Breaker for A Electric Water Heater

Choosing the wrong breaker can cause serious accidents like short circuits  Moreover, the right breaker is important for the efficiency of your heater.

What Size Breaker for a 40 Gallon Electric Water Heater? [Calculated] 1

So, you have to take some things into account before getting a breaker. These factors are: 


The first thing you need to know is the voltage requirement of your heater. An average heater can range from 220-240 volts based on size and wattage. 

Your heater needs to be placed on a circuit based on its voltage.


Similar to voltage, you need to take wattage into account. Wattage varies based on the capacity of your heater and other factors, such as size, power, features, etc. So, make sure to know the wattage of your heater.

Type of Wire 

Finally, you have to know what kind of wires are compatible with your heater. You need to keep in mind the wattage of your heater. 

Choosing an incompatible or faulty wire can cause more damage than good. 

Once you have all these factors noted, you can move to the next step. 

What Size Breaker for a 40-Gallon Electric Water Heater Should I Get? 

What Size Breaker for a 40 Gallon Electric Water Heater? [Calculated] 2

Determining the size of your breaker is actually fairly simple now. You just have to make some calculations to determine the right size of the circuit breaker for you. It’ll also help you realize the breaker size for your well pump.

In order to determine the size of the breaker, we need to find the amperage first. That can be calculated after dividing wattage by the voltage.

Afterward, determine 125% of the amperage to get a safe amount for the size of the breaker. Get the breaker that’s closest to the amperage value. Make sure the wires of the heater are of the right size as well.

Now we can start with the calculations: 

A 40-gallon water heater should have an average 4500 Watt capacity and 240 V emf. 

Wattage = 4500 W

Voltage =  240 V

Ameparage= 1500/240= 18.75A 

Considering the continual load we get, 18.75* 125% = 23.4A

Thus, a 25 or 30A breaker is sufficient for a 40-gallon breaker. However, for your safety, we recommend getting a 30A breaker.

If you’re looking for a good breaker for your water heater, here are our recommendations:

Product 1
Product 2

These are some of the very best in the market. We’re sure they’ll live up to your expectations! 

Precautions before Determining The Size of Breaker

You need to be very careful in determining the correct breaker for your water heater. If the breaker is too big or too small, it’ll only cause more trouble. 

In Case of Less Amperage

If your breaker has less amperage than required, it will trip again and again. This will turn your heater off abruptly. It can damage the internal settings of your heater as well. So, take the wattage of your switches into consideration as well. 

You can’t always use a 15 amp switch on a 20 amp circuit.

In Case of High Amperage

If the amperage is higher than necessary, it could also be very risky. It won’t respond even in cases of overload. This can severely damage your heater and other appliances associated with it. 

You finally know what size breaker you need for your 40-gallon electric heater. Now get the right one for yourself!


Question: Should I get a 4500- or 5500-watt heater?

Answer: It depends entirely on your needs. However, a 4500-watt heater is better because it requires less electricity. So, if you have similar heaters with different wattages, we recommend getting the 4500-watt one.

Question: How far does the heater have to be from the breaker box?

Answer: There should be space with a depth of 36” from the panel. Make sure the front of your heater is at least 36” from your panel.

Question: Does an electric hot water heater require a neutral?

Answer: Electric hot water heaters don’t require a neutral. However, certain manufacturers might have neutral wires along with their heaters. 

Final Words

A breaker is a lifesaver for most electric appliances. It can save your appliances from damage and protect them from irreparable losses.

However, it depends entirely on what kind of breaker you choose.

In this article, we’ve discussed everything about what size breaker for a 40-gallon electric water heater you’ll need.

We hope you find this helpful! Goodbye!