What Size Breaker for Hot Water Heater: Guide

Figuring out the right size breaker for your water heater can be a head-scratcher, but don’t worry—I’ve got your back.

The size of the breaker you need will depend on several factors, such as the wattage of your water heater, the type of wiring you have in your home, and the circuit breaker panel’s amperage rating. In general, electric water heaters require a dedicated 30-amp breaker.

  • Electric water heaters: 30-amp breaker
  • Gas water heaters: 20-amp breaker (or stronger)

Several factors determine the right breaker size for your water heater. By the end of this article, you’ll be armed with the knowledge to choose the perfect breaker for your water heating needs confidently.

Understanding Hot Water Heater Breakers

Understanding breakers for your water heater are critical for your home’s electrical system and help ensure everything stays safe and sound.

Your typical residential water heaters require a 240-volt dedicated 30-amp circuit and a 10 AWG wire size.

This 30-amp breaker will only power the water heater; no other appliances should be on the same circuit. A 30-amp circuit breaker can handle all 4500-watt water heaters, no matter their gallon size.

Determining Breaker Size for Your Hot Water Heater

Refer to the Heater’s Specifications

Before you start, knowing your water heater’s specs is essential.

I always check the wattage and voltage ratings to know what size breaker I need.

If you’ve misplaced your manual, no worries! You can usually find this information on a label sticker attached to the tank or the thermostat’s control panel.

Calculate Breaker Size Based on Wattage and Amperage

After finding the heater’s wattage and voltage, it’s time to do some math. I use this handy formula to figure out the required breaker amperage:

Breaker Amperage = (Water Heater Wattage / Voltage) * 1.25

For instance, a 4500-watt heater with a 240-volt system would require the following:

(4500 / 240) * 1.25 = 23.44 amps

However, since 23.44-amp breakers don’t exist, we commonly use a 30-amp breaker for 4500-watt water heaters.

Consider the National Electric Code Requirements

I also always factor in the National Electric Code (NEC) requirements.

According to the NEC, breakers must be able to handle a continuous load at 125%. So, to comply with that, all we have to do is multiply the calculated breaker amperage by 125%.

For example, if we calculated 23.44 amps for a 4500-watt heater:

23.44 * 1.25 = 29.3 amps

In this case, a 30-amp breaker should still work perfectly. Just remember, it’s always better to choose a breaker that’s 10 to 20 amps stronger than the suggested minimum. That way, you’re on the safe side!

Factors to Consider

When determining the right breaker size for your water heater, there are a few factors that you should take into account. Let me break it down for you.

Voltage Requirements

The first thing is the voltage requirement of your water heater. Most average heaters plug into a 220 or 240-volt outlet, depending on the tank size and wattage.

It’s important to know the specific voltage requirements of your heater to avoid any unwanted electrical issues. Trust me on this; nobody wants a fried water heater!

Heater Type

Next, let’s talk about the type of heater you have. There are electric and gas water heaters, and the breaker sizes differ for each type. You’ll typically need a 30-amp breaker for an electric water heater.

On the other hand, a gas water heater requires at least a 20-amp breaker.

gas water heater
Video | AMRE Supply

It’s essential to know the specifics of your heater to ensure you’ve got the right breaker size.

Now, there are also differences regarding the heating element wattage. For instance, a water heater with a 4500-watt heating element requires a 10-gauge wire size with a 30-amp (240-volt) circuit breaker.

Meanwhile, a 3800-watt heating element can work with a smaller 12-gauge wire and a 20-amp circuit breaker.

Electric tankless water heaters can vary in voltage, ranging from 120 to 240 volts, depending on the size and type.

So, knowing your heater’s voltage and breaker requirements is crucial to avoid electrical mishaps.

Remember, knowing your water heater’s specific voltage and breaker size requirements is key.

Common Breaker Sizes for Hot Water Heaters

Electric Water Heaters

Now, for electric water heaters, you’ll usually find that they require a 30-amp breaker. These bad boys typically use a 240-volt dedicated circuit and 10 AWG wire size.

Trust me, you’ll want to keep that 30-amp circuit just for your water heater, as sharing it with other appliances could lead to some risky business, and we don’t want that, do we?

Oh, and let me show you a little chart to make things crystal clear:

Water Heater SizeBreaker SizeWattageVoltage
50-Gallon30A4500W – 5500W240V
60-Gallon30AUp to 5500W240V
70-Gallon30AUp to 5500W240V
80-Gallon30AUp to 5500W240V
As you can see, most water heaters, regardless of size, will work with a 30-amp breaker. But as a wise man said, better to be safe than sorry, so always double-check the manufacturer’s requirements.

Gas Water Heaters

Moving on to gas water heaters, these guys need a smaller breaker. They’re a bit more lax for power requirements – and yes, they need electricity to operate.

Typically, a 20-amp breaker will suffice; however, I’d suggest going a bit above the minimum and opting for a 12-20 amps stronger breaker.

So, here’s a little recap:

  • Electric water heaters: 30-amp breaker
  • Gas water heaters: 20-amp breaker (or stronger)

And there you have it, folks! You’re now well-versed in the world of breakers and water heaters. How cool is that?

Additional Considerations

Consider a few other factors when figuring out the right size breaker for your water heater. Trust me, considering these aspects will help you make an informed decision!

Circuit Wire Size

The first thing I like to think about is the circuit wire size. The wire size directly affects your water heater’s overall performance and safety.

Choosing the correct wire size is essential, as too small of a wire can result in overheating and poses a fire hazard.

In most residential cases, a 30-amp breaker works well with a 10-gauge wire, while a 40-amp breaker pairs nicely with an 8-gauge wire.

Commercial situations may require larger wires, but that’s a different ballgame.

Water Heater Location

Yep, even the water heater location plays a role! Your water heater’s placement can impact the length of wiring needed, affecting the proper size of the breaker.

The further your heater is from the main electrical panel, the larger the wire size you’ll need and, subsequently, a larger breaker. Longer runs can lead to voltage drops, and nobody wants that.

So, the right breaker and wire size combination is key to a comfy hot shower.

Energy Efficiency

Lastly, let’s talk about energy efficiency. We all want to save some bucks while being kind to Mother Earth.

Energy-efficient water heaters generally require a smaller breaker than less efficient models, often with lower wattage elements.

So, look at your water heater’s energy efficiency rating and opt for an appropriately sized breaker.

Just remember: when choosing the right breaker size for your water heater, always factor in circuit wire size, water heater location, and energy efficiency. Doing so will surely pay off in the long run!

Wrapping Up

Regardless of capacity, most water heaters will likely require a 30A breaker. Take a 40-gallon water heater, for example; it needs a 30A breaker because it uses a 4500-watt, 240V heater.

When working with electricity, you want to make the right decisions. Ensure you’re using the National Electrical Code (NEC) guidelines, and multiply the amps by 125% for some wiggle room.

More importantly, consult the manufacturer’s manual for precise information on the current draw of your appliance.

The right breaker size for your water heater is essential for safety and efficiency. Remember, it’s all about creating a comfortable and inviting space, so take my advice and get that hot water running smoothly.




  • Electrical Wiring Residential by Ray C. Mullin and Phil Simmons
  • Wiring Simplified: Based on the 2020 National Electrical Code® (NEC) by Frederic P. Hartwell and Herbert P. Richter

Video References

Electrical Code Coach



Lowe’s Home Improvement

AMRE Supply

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About Alex Robertson

c3c9d43f1f0d14c4b73cb686f2c81c4e?s=90&d=mm&r=gCertifications: B.M.E.
Education: University Of Denver - Mechanical Engineering
Lives In: Denver Colorado

Hi, I’m Alex! I’m a co-founder, content strategist, and writer and a close friend of our co-owner, Sam Orlovsky. I received my Bachelor of Mechanical Engineering (B.M.E.) degree from Denver, where we studied together. My passion for technical and creative writing has led me to help Sam with this project.

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