what Size Breaker for a Hot Water Heater

If you have bought a hot water heater for the first time, you must want to know what size breaker for a hot water heater is perfect. You should know about it before going to use it though you aren’t familiar with it before.

The hot electric water heaters need a 240-volt 30 AMP breaker. The Q-230 30 amp Two Pole QP Circuit Breakers will perform the best.

There have some important formulas to find out the correct breaker size. In this article, we will talk about those essential factors. Continue and learn about the perfect circuit breaker sizes! 

The Importance of Breaker

An electric hot water breaker is the most common device in any home that is also known as a circuit breaker. The electric water heater runs with the safety mode of electric connection if a short circuit or over current can occur.

Every electric breaker maintains a particular electric load. For the largest electrical machine that consumes energy, they may need a dedicated circuit breaker.

The breaker breaks off the electric flow so that it can avoid circuit damage, which can be responsible for fires or electrical system failure. It performs better as a safeguarding machine to avoid electric shock from the water heater’s.

You can keep quiet to use a water heater completely safe when you have a breaker. But a wrong breaker can wind up ruining the electric appliances. So, choose the correct circuit breaker and keep safe!

Understand The Water Heater

When most of us purchase an electric water heater, we don’t give it important to check the amperage. Some machines label for voltage and wattage without ampacity. But to understand the right water heaters, you should check all of them.

How should they be?

Voltage: The voltage plays a vital role in using a boiler, and a 220 or 240 volt circuit outlet based on the boiler size is the best.

Wattage: Make your water heater’s requirement list with wattage. You can get more advantages for the right wattage. So, search what wattage your boiler demand.

Cable size: The cable size must also match the electric water heaters circuit breaker size.

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What Is The Breaker Size Solution?

Knowing the perfect size for the circuit breaker size is also very significant. If you have no idea about the AMP size, you can know it applies a simple math formula.

Amps = P/V

Note: P = Wattage

         V = Voltage

Let’s discuss it with example!

Suppose you have a water heater’s tank that the water heater’s wattage rating 3,000 watts and 120-voltages. Now you can get its amps by dividing the volts and watt water heater.

Solution: I = P/V

               I = 3000 watts/ 120 volts

               I = 25 amps

Now we hope you can find the breaker amperage if it doesn’t include them on the device’s label.

What Should Consider For The Right Size Breaker?

In this segment, we will talk about how you can select the right size breaker. In simple words, if you can choose, you can easily get the perfect circuit breaker. The things are the appropriate voltage and amperage.

Without both of them, there are some more factors that you should consider so that your investment will be worthy. Below are some requirements for the new water heater.

How Many Amps For Water Heater?

Thousand of the different circuit breaker is available in the market that can fit the different level of the device. A typical water heater requires 15-amps of power rating. Though it is an industry standard, it can vary based on different models.

According to the electrician expert, the 30 amp are the best option for the latest heater, but if you want, 20-amps won’t be less good. As the water heater is a high electric appliance, it draws more power than other electric things in your home. So, it needs high-graded power rating for more effective service.    

How Many Volts For Water Heater?

Voltage is another way to identify the essential breaker size based on your water heater. Most standard electric water heaters need 110-volts with a 15-amps range. Plus, the 20-amps circuit breakers are also equipped with 220 volts. If you aren’t sure, consult with a local electrician before deciding.

Let’s discuss industry-standard breaker size:

The industry standard breaker size will help you understand what circuit breaker size you should consider. An industry-standard water heater will require for the 240-volt circuit. Let’s see breaker size based on heater size:

40-Gallon Water Heater

A 40-gallons water heater requires a 20-30 amps breaker. You would be able to get away with a small appliance on a 30 amp circuit breaker, and the 20 amp circuit breaker also leaves less room for error and can leave more susceptible to power rating surges.

For a 40-gallons water heater, the average capacity is 4500 watts when it requires 240-volts. And the solution is: I = P/V, 4500 Watt/240V = 18.75 amps. Then think about the continuous load (125% x 18.75A) and get 23.4 or 25 amps.

With the above answer, a 40-gallons water heater requires a 25-amps breaker or a closer amperage value. But we highly recommend using 30 amp for safety breaker size. 

60-Gallon Water Heater

If you want to go above the 40-gallons water heater, you can think about a 60-gallon water heater that needs at least a 30 amp breaker. Most homes accommodate an electric water heater that contains a 30-amps breaker.       

80-Gallon Water Heater

An 80-gallon water heater is powered by 550 wattage and 240-volts. The solution of it is: I = P/V, 5500W/240V x 125% = 28.64 amps or 30 amp circuit. It is enough for a dedicated circuit breaker.

How To Size A Breaker For Hot Water Heater

When you have an idea of how to measure the breakers, it is the best time to understand how you can get the right size breaker for your electric hot water heater. Below have some steps:

First: Requirement of Heater

Most residential water heaters require about 1500-watts and 120-volts. If you feel any issue with this requirement, consult with your local electrician and make sure that you get the perfect breaker size.

Second: Divide

If the water heater needs 1500 watts and 120-volts connections, you should divide them. It will give you the total amps needed to work the water heater.

Third: Get Amperage

Most breakers constantly perform well if they have 125% power capacity, which most electric water heaters require. The means is that the 1500 watts water heater with a 120-volts connection can’t work perfectly on the 12.5-amps breaker. It offers at least 15.6-amps that can fail shortly.

The next probable option is a 20-amps circuit breaker that will work well with a 1500-watts heater. 

Fourth: Get the Right Amperage

Now, you can get right amperage based on your water heater requirements. It is most important to keep in mind that it comes to getting an ideal perfect breaker size for an electric water heater.

You shouldn’t switch from the breaker, which is very small, to larger ones that can easily reverse. You can’t replace your breaker if it needs 30-amps on the 20-amps system when you will go for the device that requires 20-amps to 30 amp circuit which transition is very easy.

Fifth: Final Selection

Finally, to make your final decision, we suggest you get a breaker that offers double the number of amps needed by the water heater. So, if your heater uses 6000 watts in a 240-volts connection, the operative amperage should be 25 amps. In this situation, you have to consider less than 35-amps.      

What Is The Right Wire Size For Hot Water Heater?

For the incompatible wiring, the connection of your water heater won’t perform well. So, ensure that the amps of the heater match its wire size. You may refer to the below list:

In terms of Amps: (Calculation based on 120-Volt)

  • 20-amps = 12-gauge wire
  • 25-amps = 10-gauge wire
  • 30-50 amps = 8-gauges wire
  • 60-amps = 6 gauges wire

In terms of wattage ratings: (Calculation based on 120-Volt)

  • 2000 watts = 10-gauge wire
  • 2500 watts = 8-gauge wire
  • 3000-3500 watts = 6-gauge wire
  • 3800-4500 watt = 4-gauge wire
  • 4800 watts = 3-gauge wire

In terms of Gallon: (Calculation based on 240-Volt)

  • 30-40 Gallon = 12 Gauge
  • 50-80 Gallon = 6 Gauge

In terms of Tankless Water heater: (Calculation based on 240-Volt)

  • 7600 Watts = 4 Gauge
  • 9600Watts = 3 Gauge
  • 11500 Watts = 2 Gauge
  • 13400 Watts = 1 Gauge

Remember that the greater the amperage rate, the thicker the wire.

Most professional electrician follows the above scheme. They always prefer 6-gauge wire for the water heater’s amperage rating exceeds 50 Amp.

What Size Breaker For A Hot Water Heater To Go?

Since you may see, it can be thicker than it seems. Choosing the breaker for a water heater has never been a simple job, so leaving it to any professional will be ideal.

If you follow the recommendations in this article and don’t overlook single details, you can get the perfect circuit breaker.

Don’t allow the water heater to be susceptible to a power problem and as an alternative, get a circuit breaker to save it with help. You can’t regret it!


Finally, depending on our guide, you can understand three wires heater ingredients – volt, watts, and wire size to get the perfect circuit breaker size.

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