What Size Breaker Do I Need For A Water Heater?

Wire Size For Water Heater Based Upon Amp, Watt, Gallon

Do you have a brand-new water heater in your home? Are you considering doing the electrical work yourself? You’ll need cables that are the proper size. A fire might be started if the improper size is used.

What Size Wire Do I Need For My Hot Water Heater?

When it comes to amperage, When it comes to wattage, For a tankless water heater, the gallon wire size is important. The thicker the wire is, the higher the amp rating of the circuit. This is the approach taken by the majority of electrical experts. Once the water heater’s amp rating surpasses 50A, they will only utilize 6-gauge wire to connect it.

How Do I Find Out What Size Wire Is Best For My Water Heater?

  1. The amperage is required in order to compute the correct wire size.
  2. Consider the following scenario: you have a 3,000W heater that operates on 120V.
  3. Following the 80 percent rule, the amperage is calculated as (3000/120)*80 percent, which results in a total of 45 amps.
  4. According to the amperage table, 8 gauge wire is the ideal wire size for a 3000W heater.
  5. You must also take these considerations into consideration.

1). Voltage

The majority of water heaters operate at 220-250V. They make use of a two-circuit breakers. Because the voltage needs of most electric water heaters are the same, you don’t have to pay as much attention to the voltage as you do to the amperage. Instead, you should pay attention to the voltage and the amperage.

2). Wattage

This measurement indicates the amount of power consumed by the water heater. The wattage of a water heater, on the other hand, cannot be used to calculate the size of the wire to utilize. You’ll require the amperage.

3). Breaker Size

  1. Technically speaking, you do not need to know the size of the circuit breaker in order to compute the size of the water heater wire.
  2. Once you’ve determined the voltage of your circuit and the wattage of the heater, you can calculate the amperage, which, in turn, shows the size of the wire.
  3. The size of the breaker, on the other hand, is equally significant.
  4. In the first place, adding a water heater to a circuit breaker of a lesser capacity may cause the breaker to trip repeatedly, which is inconvenient.
  5. It will not respond to short circuits or overloads if the breaker is installed in an improper location.

It is critical to consider the size of the breaker.Second, wire that is the same size as the breaker will most likely be sufficient to fulfill the demands of the water heater’s circuit breaker.For example, in the previous example, once you have determined the amp rating of your water heater (25A), you must increase that value by 125 percent in order to comply with NEC standards.

You will receive 31 amps as a result of this.When choosing a breaker, try for a size that is as near as possible to 31 amps in rating.The obvious solution is a 35A circuit breaker.Because of this, a 25A water heater requires a 35A breaker to be installed.A 35A breaker necessitates the use of an 8-gauge wire.

4). Gallons

  1. Those of you who have looked for a water heater before are aware that the size of the tank has an impact on the price of the water heater you ultimately purchase.
  2. Moreover, you are aware that many contractors utilize gallons to calculate the appropriate wire size.
  3. A 40-gallon heater necessitates the use of 12-gauge wiring.
  4. A 50-gallon water heater, on the other hand, necessitates the use of 6-gauge cable.
  5. The thicker the wire is proportional to the size of the tank, just as it is proportional to the amperage rating.

You do not, however, have to rely on the gallons in order to determine the wire size.In fact, if your heater includes a label that indicates its wattage, you may disregard the gallons of water it uses.In the case of a standard 40-gallon heater, the normal wattage is 2500.

Consequently, you have an amp rating of 18.75.(2500 divided by 240).In order to utilize 12-gauge wire on a 20A water heater, you must use 12-gauge wire on an 18.75A water heater.

What Kind Of Wire Should I Use?

  • You’ll need shielded metallic wires to complete the job. Pay close attention to the gauge and how it relates to the distance traveled. The majority of people are aware that a greater amp rating necessitates the use of thicker wire with a smaller gauge. They are unaware that when the distance between the two points grows, the thickness of the wire should rise as well. Water Heater is a related post (Red, Green, Blue) Light Blinking/Flashing Symbolism
  • Does a Water Heater Require a Disconnect Switch? Explanation of the amp, height, and size

How Many Wires Does A Water Heater Need?

  1. A water heater necessitates the use of three wires: a black wire, a white wire, and an earth wire.
  2. The white and black wires of a 10-2 ground shielded cable serve as hot conductors in this configuration.
  3. The neutral wire will be connected to the ground wire.
  4. It is the black and red wires that are the hot conductors in a 10-3 ground shielded cable with an extra conductor if the cable has a total of three conductors.

Why Does Wire Size Matter For My Hot Water Heater?

  1. It is more probable that a wire that is too tiny (with a higher gauge number) may melt and cause a fire.
  2. This is due to the fact that the water heater will compel the wire to carry more power than it is capable of delivering.
  3. Overheating will result as a result of this.
  4. Please keep in mind that a smaller diameter corresponds to a higher resistance.
  5. Furthermore, the higher the resistance of a wire, the more heat it will emit.

When it comes to gauge, the smaller the wire is, the higher the number on the gauge is.The bigger the wire, the lower the wire number is.Taking the example of wire gauge, a 6-gauge wire is thicker than a 10-gauge wire.

The use of larger cables is not an issue.It is preferable to utilize larger cables than it is to use smaller wires.Unless you have a shoddy wiring job on your circuit, a bigger cable is unlikely to have any serious repercussions.The expense, on the other hand, is expected to climb.You may not be aware that bigger cables are more expensive than their thinner equivalents.

It’s important to choose wire that is the proper size for the wattage of your heater in order to avoid excessive costs and perhaps disastrous fires.

Does A Hot Water Heater Have To Be Hardwired?

  • It is not necessary to have a hardwired system. An electric water heater necessitates the installation of a dedicated 240V circuit. You should be able to connect your heater to a 30A double pole breaker, depending on the wattage of the heater. It is not necessary to hardwire your water heater in order for it to satisfy these fundamental standards. As a result of the only thing they can see, many people believe that a water heater must be hardwired. Those who believe in the dangers of cord and plug water heaters believe that the water heater will ultimately overload one or both of the power cable and the wall outlet. However, this is not the case. The first thing to mention is that cable and plug water heaters are extremely widespread. It is dependent on your geographical location.
  • Second, they are often smaller and less powerful than their larger counterparts.
  • Third, the power cables for the chord and plug water heaters are placed by the manufacturer at the manufacturing facility where the heaters are produced. They are thick enough to withstand the electrical needs of the heater without overheating
  • fourth, if the heater is linked to a dedicated circuit, you won’t have to worry about overloading the outlet
  • and fifth, you won’t have to worry about overheating the heater. It should be the only appliance connected to that circuit at any given time. The water heater’s outlet can be designated as the only outlet on the circuit, which will discourage others from adding other devices to the circuit.

Other outlets on the circuit can be blocked from being used by other individuals by placing tape over the slots on the circuit.

What Does The NEC Say About It?

  1. 1) Fixed-storage water heaters are classified as continuous loads under the National Electrical Code.
  2. It is necessary to have temperature-limiting functions in the controls.
  3. 3).
  4. According to the National Electrical Code Association (NECA), the circuit rating should be at least 125 percent of the heater’s amp rating.
  5. 4).

The National Electrical Code (NEC) anticipates that users will utilize 10/2 conductors for heaters rated at 4500W.Check the fire and electrical codes in your area.If it specifies the wire diameters that should be used for water heaters of specific ratings, you should pay attention to it.

Can I Use 10 3 Wire For A Hot Water Heater?

You may use a 10/3 wire for this project. The red and black wires should be used as hot conductors. The ground wire will be routed to the green screw on the bottom. Remove the cap from the white wire. Your electrician will not be able to purchase 10/3 wire for your heater. However, if you have already purchased one, they will be able to make it work.

Can I Use 10-2 Wire For A Water Heater?

A 10/2 cable can be used in this situation (with a ground wire). Water heaters are often wired using this type of cable, which is the most popular type used by electricians. A 10/2 cable is composed of two conductors. It is ideal for breakers with a current of 30A.

Can You Use 12 2 Wire For A Water Heater?

  1. There is nothing wrong with utilizing 12/2 wires in your installation.
  2. However, I recommend that you utilize 10/2 wires.
  3. Even if you have a smaller water heater with a lesser wattage, 10/2 wires allow you the flexibility to upgrade your water heater in the future if your needs change.
  4. If you decide to upgrade to a larger, more powerful unit in the future, you will not have to go through the hassle of changing all of the wiring.

What Water Heater Breaker Size Do I Need? (Electric Wiring Explained)

  1. In general, electrical tankless water heaters require specialized electrical installation due to the fact that their load requirements are larger than those of other types of electrical equipment.
  2. It is critical to have the proper type of breakers in place in order to avoid electric overloads and blackouts.
  3. The following essay is intended for those who have pondered the topic, ″What water heater breaker size do I require?″

How is a Water Heater Breaker Measured? 

  1. Amperes are the unit of measurement for water heater breakers.
  2. Amperes are a unit of measurement for current, or the amount of electricity flowing through a circuit.
  3. It is equal to the voltage of the circuit divided by the entire resistance of the circuit that represents the current.
  4. It is necessary to have breakers in place in order to halt current flow when a malfunction in the electrical system is identified.
  5. They must not only avoid harm, but they must also be able to handle a particular current without shutting down.

The average ampere consumption of a water heater is around 19.9 amps.A tankless electric heater consumes around 100 to 120 amps to operate on its own.

Considerations When Sizing Breakers for a Water Heater 

Power Rating Of Your Heater 

The current drawn by your water heater system must be handled by circuit breakers. The greater the size of your tankless heater arrangement, the greater the amount of electricity your breakers must be able to manage. For the average water heater system, a 30 amp circuit breaker or greater is required.

Maximum current drawn 

You must ensure that your circuit breakers have enough capacity to manage the whole current flow. A 20-amp water heater, for example, requires a circuit breaker that is capable of handling at least 20 amps of electrical electricity. You must also ensure that your electrical system has been updated to supply the right quantity of current, or else it will not function correctly.

Current rating of your breaker 

Most homes are equipped with 15-20 amp circuit breakers, which are intended to withstand around 80 percent of their total amperage consumption. As a result, a 15 amp breaker can take approximately 12 amps while a 20 amp breaker can handle approximately 16 amps. Most likely, you will need to make changes to your home’s electrical system in order to draw additional power.

What Water Heater Breaker Size Do I Need? (How to Calculate) 

  1. Calculating the appropriate breaker size for your heater is a pretty simple process.
  2. You must first determine the machine’s power rating (measured in watts or kilowatts) as well as the voltage that it requires.
  3. Because current is just the product of power divided by voltage, you may calculate the magnitude of the breaker current necessary for your heater by dividing these two values in half.
  4. Consider the following scenario: you have a normal 1,500-watt water heater that operates on a 120-volt system.
  5. 1,500 divided by 120 equals 12.5, which means you’ll need at least 12.5 amps of current to get the item running.

Most breakers, on the other hand, are intended to operate at just 80 percent of their maximum load capacity.Consequently, to meet our 12.5 amp current needs, we would want breakers that could withstand at least 15 amps of power.In an ideal situation, you should be able to identify breakers that can manage at least 125 percent of the demands of your water heaters.

On a 120-volt circuit, a 50-gallon tank consumes around 4,500 watts of electricity.Using the arithmetic, that works out to around 37.5 amps in total.According to the 125 percent guideline, we require breakers that have a minimum capacity of 47 amps.As a result, seek for breakers that can handle 40-50 amp loads.

Water Heater Breaker Size Chart 

The following table indicates the sizes of circuit breakers and copper wire that are necessary for tankless water heater units. Please keep in mind that these are only educated guesses. Always be sure that you are following the exact directions provided in your user’s handbook.

People also Ask (FAQs)

Can I replace a 30 amp breaker with a 60 amp breaker? 

This is only possible if you also replace the cable with one that can handle the additional current. A fire might occur if you simply switch the 30 amp breaker out for a 60 amp breaker without additionally altering the wires in the circuit.

What size wire should you use for a 60 amp breaker? 

To safely operate a 60 amp breaker without the risk of damaging it, you must use at least a 6 gauge (4.1mm) wire; the higher the current, the thicker the wire you must use.

See also:  How Much Does A Water Heater Cost
Can I use a 40 amp breaker for a water heater?

Yes, it is possible to utilize a 40 amp breaker for some water heaters. Some tankless electric water heater units may be powered by 40 amp circuit breakers as well.

How many amps can a 30 amp breaker handle? 

A 30 amp breaker is capable of handling currents of up to 30 amps, although it is only suggested for usage at voltages of about 25-26. Generally speaking, a breaker should only be utilized at around 80% of its maximum amperage rating.


Electric hot water heaters consume significantly more electricity than other equipment, therefore you must ensure that you have the appropriate circuit breakers and cables installed. As a result, be certain that your water heater system is equipped with the appropriate breakers.

What Size Breaker Does a Water Heater Need?

  1. Circuit breakers are required for the operation of your electric water heater and gas tankless water heater.
  2. Choosing the incorrect size circuit breaker, on the other hand, might result in poor safety and even damage to the water heater.
  3. Because of the increased electrical flow via the breaker, the wires are at risk of overheating, resulting in a fire and inflicting damage to your water heater.
  4. To ensure electrical safety, the National Electrical Code lays forth rules for the size of circuit breakers and the wire that they are connected to.
  5. According to the National Electrical Code, your circuit breaker should always be sized at 125 percent of the load.

For safety reasons, it is suggested that you purchase a circuit breaker with more capacity than the electrical load of your electric devices – in this example, your water heater – to ensure that you are not electrocuted.Electric water heaters require a dedicated 240-volt dedicated 30-amp circuit as well as a non-metallic (NM) or multi-core (MC) cable with a diameter of 10-2.This indicates that the breaker only provides power to the water heater and does not provide power to other appliances.

An electrical circuit breaker rated at 30 amps can run all 4500watt water heaters, regardless of their gallon capacity.On occasion, I’ll come across a 4500-watt water heater that has a 20-amp circuit breaker.The fact that this is theoretically right in terms of size is that it leaves little space for overcurrent and does not comply with the NEC’s 125 percent load standard.The size of the breaker is decided by the wattage of the heating components, not the size of the storage tank.More on it in a moment.

A water heater with a 4500-watt heating element necessitates the use of a 10/2 wire and a 30 amp (240-volt) circuit breaker to be installed.The 3800-watt heating element may be wired using a smaller 12/2 wire and a 20 amp circuit breaker, which will save on wiring costs.

Sizing Water Heater Breakers 

  1. Understanding how a water heater works is essential to determining the appropriate size for the heater to be installed.
  2. Electric water heaters operate on alternating current, which ranges from 220 to 250 volts in voltage.
  3. You’ll need a double circuit breaker that’s rated appropriately for the amount of electricity the water heater is drawing.
  4. For most electric water heaters, we’re looking at a current of between 20 Amp and 30 Amp.
  5. When determining the appropriate size based on the power needs, it is also necessary to consider the wire gauge size.

The wire gauge size is determined by the amount of current drawn by the heater.

How Do You Calculate Breaker Sizing?

  1. The power and voltage ratings of your water heater should be checked.
  2. The wattage and voltage rating of a water heater are labeled on a sticker that is attached to the thermostat panel.
  3. This information may be found around the base of certain heaters.
  4. While the majority of household water heaters have a capacity of 4500 watts or less, commercial water heaters can exceed 5500 watts or more.
  5. Let’s get down to the nitty gritty of determining breaker sizes using arithmetic.

4500 divided by 240 equals 18.75 amps.18.75 times 125 percent equals 23.4375 amps, which is rounded to 25 amps.If you have a 4500-watt water heater that runs on 240 volts, you should be able to get 18.75 amperes out of it using the conventional division formula.

Keep in mind, however, that an electric water heater operates on a continual load.As a result, multiply 18.75 by 125 percent to account for the fact that a water heater operates on a continuous load.To get 23.4375 amperes, multiply 18.75 amperes by 1.25 to get 23.4375 amperes.When we round that value down to the next tenth, we obtain 25 amp.You’ll need a circuit breaker with a capacity of 25 or 30 amps.

It is commonly utilized because the minimum rating of 220 volts is greater than the 25 amp rating of the 25 amp breaker.4500/220 = 20.45 amps is the result.20.45 amps multiplied by 125 percent equals 25.568 amps, which is rounded to 30 amps.Why not make it twenty?After all, it’s closer to 18.75 than 18.75.

  1. Well, 18.75 amps is only around 94 percent of the total amperage of the breaker.
  2. However, according to the National Electrical Code’s 125 percent guideline, a 20 amp circuit poses a danger of frequent tripping and might cause damage to the water heater.
  3. A 25 amp circuit breaker is sufficient; however, most electricians will construct a 30 amp circuit to allow for electrical fluctuations, as described above, to be accommodated.

What Size Circuit Breaker for Gas Tankless Water Heaters?

  1. Compared to electric tank water heaters, gas tankless water heaters consume less electricity and produce less voltage.
  2. Typically, it’s around 12 amps and less than 120 volts in voltage.
  3. In order to power the electronic ignition system on gas tankless water heaters, a little quantity of electricity is required.
  4. A gas tankless water heater only requires a dedicated single-pole breaker with a 15-amp, 120-volt rating for this reason.

Should I Have Electric Water Heater or Gas Water Heater?

  1. This decision is based on your geographic location as well as the utility costs in your region.
  2. Gas water heaters, on the other hand, are often more expensive to purchase up front but less expensive to operate than electric water heaters.
  3. In contrast to gas water heaters, electric water heaters are more energy efficient than their gas counterparts.
  4. The cost of gas is 40 percent more than the cost of electricity.
  5. As a result, it would be more cost effective to utilize gas.

Electric water heaters, on the other hand, are more cost-effective when considering the time saved over time.Choosing the proper size circuit breaker can be a complicated process.If you’re considering making changes to your home to accommodate electric, gas, or tankless water heating systems, you should consult with a professional first.

DISCLAIMER: The information provided on HomeInspectionInsider.com is not intended to be professional guidance.Before beginning any job, you should contact with a competent expert and verify that all necessary permits have been obtained.It is owned and operated by Hubert Miles who is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by placing advertisements and links on their websites that direct traffic to Amazon.com (hereinafter referred to as ″Amazon.com″ or ″Amazon.com Associates Program″).As an affiliate, HomeInspectionInsider.com participates in a variety of affiliate programs with other websites.Hubert Miles receives a commission for recommending visitors and commerce to these businesses.

What Size Breaker Do I Need for a Water Heater? – USAwaterquality

  1. Are you concerned about blowing a fuse in your water heater or causing a fire in your home because you did not utilize the proper circuit breaker?
  2. I understand how you’re feeling.
  3. I also considered what size circuit breaker I would use for a water heater.
  4. Choosing the incorrect circuit breaker might have catastrophic ramifications.
  5. I will assist you in determining the appropriate size of circuit breaker to utilize for your water heater, as a result of which

How Does a Conventional Water Heater Work?

  1. Before I lead you through the process of choosing the appropriate size of circuit breaker to utilize in your water heater, let’s go over the fundamentals first.
  2. Two thermostats and two heating elements are often found in the top and lower parts of an electric water heater’s tank, which is divided into two pieces.
  3. Once the tank is completely filled with water, the upper thermostat activates its heating element, which raises the temperature of the water in the upper half of the tank.
  4. Heat rises from the bottom, triggering the lower thermostat and igniting the heating element in the lower thermostat.
  5. Around this time, the higher thermostat turns off, indicating that it has completed its intended function.

The lower thermostat, on the other hand, continues to manage the lower heating element until the water heater reaches the temperature that is wanted.After then, it turns off.The lower thermostat is set to switch on and activate the lower heating element for about 1 to 4 minutes per hour, 24 hours a day, seven days a week.

It accomplishes this in order to keep the water at its optimal temperature.

How Does Electricity Heat the Water?

  1. According to what we discussed before, your water heater need power to activate the heating elements in order to function.
  2. A conducting wire is pushed through by the voltage of your home’s electrical system, which is measured in amperes.
  3. All cables have resistance, which reduces the amount of electricity that flows through them.
  4. In addition, it generates heat.
  5. When the electrons reach the heating element of the water heater, the voltage causes the electrons to be pushed through a resistance wire within the heating element by the current.

Designed by engineers to withstand intense temperatures without melting, these resistance wires are used in many applications.In addition, when the resistance wire heats, the water in your tank warms as well.

What is a Circuit Breaker and Why Do You Need It?

  1. Remember how we discussed how the voltage pushed the electrons across the wire, causing heat to be generated?
  2. If there is an excessive amount of heat applied to the wires, the wire covering may melt, resulting in a fire.
  3. There must be a system in place to prevent the flow of energy from the power source to the water heater from continuing.
  4. The electrical supply from the source to the heating elements is interrupted when there is an excessive amount of power going through the circuit, which causes the circuit breaker to ‘trip.’ For better or worse, it disconnects the water heater from the power supply, preserving the integrity of the appliance as well as your home.

What is the Correct Circuit Breaker Size?

  1. Circuit breakers are rated by their manufacturers based on the maximum amount of electric current (measured in amperes) that they can handle without tripping or breaking the circuit.
  2. When sizing an overcurrent safety device, such as a circuit breaker, electricians are required to follow the 80 percent rule, which is outlined in the National Electrical Code (NEC).
  3. It is required by code that a circuit breaker should not be able to handle more than 80% of the electrical rating on it.
  4. Using the 80 percent rule, you can reduce the amount of heat created in an electrical circuit while running it at full capacity for at least three hours.
  5. A circuit breaker rated at 125 percent of the power rating of the appliance should be installed on a machine that runs constantly 24 hours a day.

For devices that don’t require a constant electrical demand, circuit breakers with 100 percent of their rated capacity can be used to accommodate them.Given the fact that water heaters are constantly in use, it would be prudent to size your circuit breaker at 125 percent of its maximum rating.

What Size of Wiring Do I Need for My Water Heater?

  1. It is a common rule of thumb that the smaller the diameter of an electric wire, the more quickly it tends to heat up.
  2. It is for this reason that a wire with a big gauge is recommended.
  3. For 4500-watt water heaters, the National Electrical Code advises using a gauge 10 nonmetallic or metal-clad electric wire with two conductors (10/2) as recommended by the NEC.
  4. If your water heater has heating components that generate 3800 watts, you can utilize a 12/2 wire (Gauge-12 and two conductors).
  5. It’s also vital to remember that your water heater will require a dedicated power and breaker system to operate properly and safely.

The majority of the equipment we have at home are powered by 110-120 volts of electricity.240 volts are required by water heaters in order to drive electrons through the wires.In addition, because your water heater operates on 240 volts, a double-pole circuit breaker must be installed.

This CB type is equipped with two live wires.If a fault arises in one of the wires, it will cause the other to trip, resulting in the electricity to the water heater being shut off.

How to Determine the Correct Breaker Size for Your Water Heater

  1. In this section, we will discuss how to identify the proper circuit breaker size for your water heater.
  2. Here are three simple steps to follow.
  3. 1.
  4. Determine the power and voltage ratings of your water heater.
  5. In most cases, the information may be found on a label sticker that can be found at the water heater’s power cable base or the thermostat control panel.

If you are unable to locate this information, you may choose to consult the owner’s handbook or conduct an online model search.The majority of water heaters are equipped with a 4500-watt element that operates on a 240-volt system.Commercial-grade devices can have more than 5500 watts of power, whilst lesser units can have just 3000 watts or less.

2.Calculate the maximum electrical current (amperes) that your water heater requires by dividing the wattage rating by the voltage of your water heater.Consider the following scenario: you have a 4,500-watt water heater running on 240 volts.4.500 240 = 18.75 amperes, which is the result of our formula.3.

Increase the computed figure by 125 percent to account for the fact that a water heater operates on a continuous load.We shall multiply 18.75 amperes by 1.25 to get 23.4375 amperes as a result of this calculation.In other words, a 4500-watt, 240-volt water heater will require a circuit breaker with a capacity of 25 or 30 amperes, depending on the model.Given that the water heater only uses 18.75 amperes at 240 volts and 4500 watts, you would conclude that a 20-amp circuit breaker is sufficient for the job.In the case of circuit breakers, the current of 18.75 amperes already accounts for 93.75 percent of the total capacity.

  1. Remember the 80 percent guideline from the National Electric Code?
  2. In spite of the fact that a 20-amp circuit breaker may be functional, there is no assurance that your system will not trip or cause power disruptions.
  3. In order to determine how much heat the electrical wires generate within the cables, there is no method to measure it.

A 30-amp circuit breakers makes perfect sense since it provides the system with adequate capacity to deal with any potential problems that may arise as a result.

What Size of Circuit Breaker Should You Use for a 5500-watt Water Heater?

A 5500-watt, 240-volt water heater requires 22.9 amperes in order to function properly. Taking the result and multiplying it by 1.25 gives you a final ampere rating of 28.645. As a result, a 30-amp circuit breaker should be enough for this installation.

See also:  How To Properly Size A Tankless Water Heater?

What Size of Circuit Breaker is Ideal for a 50-gallon Water Heater?

The heating components in most 50-gallon water heaters have a capacity of 4500 watts. 4500 watts divided by 240 volts is 18.75 amperes, which is a reasonable estimate. When you multiply 18.75 amperes by 1.25, you get a value of 23.4375 amperes. A circuit breaker with a capacity of 25 or 30 amps is recommended.


  • You should constantly remember the following methods in case you ever find yourself wondering what size breakers I need for a water heater. Make a note of your water heater’s voltage and wattage specifications
  • The amperage rating of the water heater is calculated by dividing the power by the voltage.
  • To get the appropriate circuit breaker size, multiply the amperage rating of the water heater by 1.25.

Isn’t that straightforward? You may use this simple method to figure out the size of the circuit breaker required for practically any electrical item in your home or office.

What Size Breaker for a Hot Water Heater: A Breaker Size Solution

  1. Is your electrical water heater tripping the breaker on a regular basis?
  2. Is it possible that your heater overheated without you noticing?
  3. You have clearly indicated that you are experiencing difficulties in matching your appliance with its safety device based on just a few questions.
  4. What size breaker do you recommend for a hot water heater, I hear you ask?
  5. For the most part, 30-amps is the common size for heaters.

It is important to note that this breaker ampacity does not necessarily work for every water heater available.There is a formula for determining the proper breaker size, but there are other important aspects to consider, which we will discuss later in this article.

Understanding Your Water Heater

  1. When purchasing an electric water heater, one of the most common mistakes made by homeowners is failing to verify the amperage rating of the unit.
  2. Some heater tanks are just labeled with the voltage and wattage requirements, but not with the ampacity requirements.
  3. It is preferable if you obtain your tank specs from the shop or the brand manufacturer directly themselves.
  4. The size of your heater must serve as the foundation for establishing the appropriate breaker size.
  5. The following are the three criteria you should examine in order to assure your safety: Voltage- The volts provided by your boiler are critical to the operation of a properly functioning circuit.

Depending on the size of your tank and the power of your heater, you can connect it to a 220 or 240 Volt outlet.Wattage- Include the wattage requirements for your heater in your list.Knowing the wattage of your gadget is extremely beneficial if your equipment often consumes a large amount of power due to its tank size and other features.

It will assist you in your quest for a proper breaker to manage the situation.Wire Size- Finally, it is critical to understand which cable type is suitable with the breaker size of your hot water heater system.An mismatched size or broken cables that have been reused might put your heater and breaker at greater risk than they are worth.

A Breaker Size Solution: What’s the Formula?

  1. If you’re unsure of the amp size you’ll need, doing a simple calculation will provide the answers you need.
  2. Knowing the wattage and voltage of your water heater already, all you have to do is follow the Ampere formula, which is I (amps) = P (watts)/V (voltage) (volts).
  3. As an example, I have a 3,000-watt heater tank that requires 120-volt power to operate.
  4. You must divide your watts by the number of volts in order to obtain its amperage.
  5. Solution: P/V = I = P/V I is equal to 3000 watts x 120 volts.

I equals 25 amps.You could be thinking that a gadget with a current of 25 amps necessitates the use of a breaker with the same capacity.After all, it is at this point when overloading and over-tripping begin to occur.

The National Electric Code (NEC) stipulates that you must maintain a continuous load of 125 percent of the maximum continuous load at all times.In order to acquire the safe amount for your electric water heater breaker size, you must first complete this step.Applying the continuous load rule to the previous example, we get 31.25 amps: 125 percent x 25 amps = 31.25 amps.If this is the case, you can purchase the nearest amp size, which is 35 amps.The Square D by Schneider Electric HOM235CP is a highly recommended device for a 35-amp circuit breaker.

If you have a 20-amp breaker devoted to your 25-amp water heater, you should anticipate the heater to trip the breaker on a regular basis.Allowing enough room for your breaker will allow a power surge to occur without triggering the breaker.Check out this video from House Wiring T.V.to get a better understanding of how to properly size your water heater wires and breakers!- Video on YouTube

What Size Breaker for 40 and 80-Gallon Water Heater?

  1. Most households utilize a water heater with a tank capacity ranging from 40 to 80 gallons, depending on how much they rely on warm water on a daily basis.
  2. You’ll need their wattage and voltage to figure out how many amps breaker for water heater of these tank sizes you’ll require, and then you’ll use the answer from earlier.
  3. The typical capacity of a 40-gallon heater is 4500 Watts at 240 Volts, according to the manufacturer.
  4. Using the formula I = P/V once more, 4500W/240V Equals 18.75 amps.
  5. Then, taking into account the continuous load (125 percent x 18.75A), we’ll arrive at a total of 23.4 amps.

According to our response, a 40-gallon water heater requires at the very least a 25-amp breaker, which is the closest match to the amperage amount.However, I strongly advise utilizing 30-amp breakers because they are a more secure breaker size.For example, an 80-gallon heater fueled by 5500 watts and 240 volts will result in 5500W/240V x (1.25 continuous load) = 28.64 amps while operating at 5500W/240V.

This means that a 30-amp dedicated circuit breaker is sufficient.Pro-tip: Although a 30A breaker appears to be insufficient for an 80G tank, putting a 40A breaker will not safeguard the device in the event of an overloaded circuit.A breaker amperage that is far higher than necessary will not trip when it is required.

What’s the Correct Wire Size for a Water Heater?

  • If the wiring between a water heater and its breaker is mismatched, the connection will not function properly. Check that the amperage of your heater corresponds to the size of the wires on it. You can use the following list as a guide: 20-amp heaters require 12-gauge cable
  • 25-amp heaters require 10-gauge wire
  • 30/40-amp heaters require 8-gauge wire
  • and other big heaters up to 50-amps require 6-gauge wire.

Also, evaluate the size of your water heater’s circuit breaker. Circuit breakers rated at 30 amps, which are often used for big boiler tanks, require a 10-2 nonmetallic or MC cable. It is appropriate for starting loads up to 40 amps and a steady load up to 35 amps with this type of wire.

Preventive Measures Before Buying a Circuit Breaker

  1. When selecting the appropriate water heater circuit breaker size, it is important to be mindful of the amp differential between the breaker and the water heater.
  2. It’s critical that you obtain the correct size.
  3. A breaker that is either too large or too little might result in an electrical hazard.
  4. If your circuit breaker is too tiny for the amperage needs of your water heater, you should anticipate your CB to trip on a regular basis.
  5. Not only that, but too much switching on and off of the heater might result in internal damage to the device.

It is not recommended that your water heater share a circuit with other appliances, and you should consider upgrading the circuit breaker if necessary.A breaker that is capable of handling a larger amperage than designed does not always imply that it is safer for the heater.If the tank experiences a sudden short circuit or overload, your circuit breaker will ignore the occurrence, providing no protection at all.


  1. Choosing the appropriate size circuit breaker for a hot water heater is not that difficult if you obtain the necessary information.
  2. You can determine the right breaker size simply by studying the three wire heater factors — voltage, wattage, and wire size — and how they interact.
  3. A basic calculation would also suffice, but keep the breaker size as close as possible to the quantity of your response (the actual amp size of the heater).
  4. A 30-amp circuit breaker is commonly used for an electrical water heater, thus a circuit breaker such as the Q230 30-Amp Double Pole Type QP Circuit Breaker will be suitable for the job.

What Size Breaker for a Hot Water Heater? – SaveourH2O

  1. What kind of electric water heater do you have at home?
  2. For example, you might want to find out what size breaker you should use for a hot water heater before purchasing one.
  3. In order for your water heater to function properly, you must have a circuit breaker installed.
  4. The majority of electric heaters require a 240-volt dedicated circuit; this circuit requires a 30-amp two-pole breaker and a 10-2 nonmetallic cable or metal-clad cable, among other components.
  5. The size of your water heater’s circuit breaker should be proportional to the electrical requirements of the heater.

How Does A Circuit Breaker Work?

  1. How many people in your household have an electric water heater?
  2. Obtaining information on what size breaker to utilize for a hot water heater may be of interest to you at this point.
  3. Having this criteria is essential since the circuit breaker safeguards the electrical system of your water heater.
  4. 240-volt dedicated circuit: Most electric heaters require a 240-volt dedicated circuit with a 30-amp two-pole breaker and a 10-2 nonmetallic cable or metal-clad wire.
  5. The size of your water heater’s circuit breaker should be proportional to the electrical requirements of the unit.

How To Find The Proper Breaker Size For Water Heater?

  1. When determining the exact breaker size you want for your water heater, it is critical to consider the capabilities of the circuit that will be serving the water heater.
  2. When designing a circuit, you should ask yourself, ″What is the greatest amount of electric current that I wish to pass through the circuit?″ According to the National Electrical Code, the size of the circuit breaker shall not be less than 125 percent or more than 125 percent.
  3. We must follow these four simple procedures in order to determine the suitable breaker size.
  4. Hopefully, at the end of this discussion, you will be able to make an informed decision about your water heater’s circuit breaker.
  5. Calculate the power rating of the water heater.
  1. Identifying the existing rating of your water heater should be the first step in the process of upgrading your system.
  2. This information may be found on the heater’s specification label, which is located on the side of the unit.
  3. Residential water heaters are typically rated at 1500 watts of energy consumption or less.
  4. If your heater is powered by a 240-volt circuit, it consumes 4,500 watts.
  5. If a water heater has two heating elements, you will see two different wattage figures – but they will not be operating at the same time.

A water heater with two elements, each of which has an energy rating of 4,500 watts, will utilize a total of 4,500 watts when operating at its full capacity.It is not necessary to add the two wattages together.Using your water heater’s maximum current, figure out what it is.

  1. Identification of the maximum current draw of your water heater is critical since it will aid you in the selection of an appropriate circuit breaker for its overall operating system.
  2. The recipe is simple and quick to use.
  3. Calculate the power rating of your heater by multiplying it by the operating voltage.
  4. If your electric water heater consumes 1,500 watts and is connected to a 120-volt circuit, you would need to divide these two variables by a factor of 2.
  5. As a result, you’ll receive a total of 12.5 amperes.

Find out what the optimal amperage is for your water heater.

  1. Why is it critical to ensure that the right operating amperage is used?
  2. This is due to the fact that the breaker size may not be compatible with the operating voltage of your heater in some instances.
  3. When using a 1500-watt heater on a 120-volt circuit, the circuit should have at least 15.6 amps of current.
  4. A 15 amp breaker, on the other hand, could be a little inadequate for this design.
  5. As a result, a more powerful circuit breaker would be required.

A 20-amp circuit breaker would most likely be the most appropriate choice.Find out what your load breaker’s current rating is for both continuous and non-continuous loads.

  1. This step will provide you with the information you need to determine what breaker size you should purchase.
  2. Multiply the existing rating’s value by 125 percent to get the new rating.
  3. Homeowners frequently believe that the maximum amp of their water heater corresponds to the same amount of breaker amperage.
  4. This is not always the case.
  5. Because each circuit breaker can only utilize 80 percent of the total amperage available, it is generally recommended to purchase circuit breakers with a greater amperage rating.

For example, a 15-amp breaker has a maximum capacity of 12 amps, but a 20-amp breaker has a maximum capacity of 16 amps.Circuit breakers and Overcurrent Protection Devices are typically built to handle 100 percent of the rated current in most cases.It is possible to employ a smaller breaker in this situation, which is particularly relevant when dealing with non-continuous loads.

Nevertheless, for continuous loads, the 125 percent suggestion is recommended in order to achieve a safe current limitation.As a result, the situation described in instance number three applies here as well.It is critical to know the load capacity of a circuit breaker..We must make certain that our water heater is suitable with the circuit breaker that we select.Calculate the size of a 30A non-continuous load water heater’s circuit breaker using the following example: When dealing with a 30A non-continuous load, you can utilize a 30 amp circuit breaker.

It is permissible to give this a current rating of exactly 100 percent.Accordingly, 30A non-continuous load equals 30A circuit breaker.There is no need for any additional adjustments or calculations.Calculate the size of a 28A continuous load water heater’s circuit breaker using the following example: In this scenario, we must multiply a continuous load of 28A by 125 percent in accordance with the NEC’s specifications.35 A is equal to 1.25 times 28 A.

  1. As a result, the breaker size is equivalent to 125 percent of the continuous load.
See also:  What Size Gas Line Is Needed For Tankless Water Heater?

Points To Remember When Choosing A Circuit Breaker Size

  • The 125 percent figure is only applicable to continuous loads, not intermittent loads. It is compatible with the vast majority of water heaters that operate on 240-volt circuits.
  • If you’re just intending to use your water heater periodically (i.e., not on a continuous basis), a circuit breaker with a 100 percent rating would suffice.
  • A 30 amp breaker necessitates the use of a 10 gauge wire. Both devices are suitable for use with 240V heaters.
  • It is important to remember that if you have other devices connected to the same circuit as your water heater, you must include their amperage in the overall current demand.
  • It is possible to lose the safety function of your breaker if you lower the size of the breaker without updating the entire wiring and circuitry.
  • When there is poor wiring, a circuit breaker will trip and break quickly.
  • It is possible that a broken thermostat can cause your breaker to use more power, which will eventually cause it to trip.
  • Unless the load current is very high, breakers cannot be much greater than the ampacity of the wire.
  • It is recommended that you utilize a circuit breaker with a capacity double the amperage of your water heater.
  • Always double-check that the circuit breaker you’re installing is compatible with your current panel.


  1. It might be difficult to determine the correct breaker measurement.
  2. It is usually a good idea to consult the specification sheet of your hot water heater when putting together information regarding what size breaker to use with your hot water heater.
  3. You will use it as a starting point for your circuit breaker sizing calculations..
  4. By following the methods outlined above, you will be able to determine which kind will function most correctly with your water heater.
  5. There should be no assumption about the effectiveness of this action plan, which assures that your water heater will not have any electrical problems.

What size breaker do I need for a water heater?

  1. Asked in the following category: General The most recent update was made on the 25th of January, 2020.
  2. Electric water heaters necessitate the installation of a 240-volt dedicated circuit that serves only the water heater and none of the other appliances or devices on the circuit.
  3. In most cases, the circuit wiring will consist of a 30-amp double-pole breaker and 10-2 non-metallic (NM) or multi-conductor (MC) cable.
  4. The wiring requirements for 3800 watt elements are less strict than the wiring requirements for 4500 watt components.
  5. In order to power a 4500-watt element, 10/2 wire and a 30 amp (220volt) breaker are required.

The 3800 may be connected with 12/2 wire and a 20 amp breaker, depending on your needs.In the same vein, what size circuit breaker do I require for a 50 gallon water heater?In order to accommodate a water heater, the usual circuit configuration is 10 conductors with ground (10/2), with a 30 amp circuit breaker for the water heater.

In the same vein, what size circuit breaker do I require for a 30 gallon water heater?A water heater of this sort must be treated as a continuous load, which means that the branch circuit must be estimated at 125 percent of the heater’s rated ampacity in order to be considered safe.4500/240 = 18.75 amps can be run on a 20 amp OCPD, however 18.75*125 percent = 23.4 amps necessitates a 25 or 30 amp circuit, depending on the manufacturer.Approximately how many amps does a 50-gallon water heater consume?The majority of 50 amp water heaters will have components that are 4500 watts.

No, a 20 amp circuit breaker will not trip if the load is 4500 / 240 = 18.75 amps, but it will be working at over 95% of its 20 amp capacity, and most circuit breakers are not rated to handle that much current.

wire size for 50 gallon Rheem

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 wire size for50 gallon Rheem
Author: chip (OH) would10 wire be safe for a 50 gallon rheem 240 volt water heater with 3500 watt elements on 2 20 amp breakers?the romax is currently 12-2 from the breaker box to the heater is around 30′ i was thinking of upgradeing to10 would that be ok on 2 20 amp breakers? thanx Chip
Post Reply
 Re: wire size for50 gallon Rheem
Author: Dunbar (KY) 10 wire is rated for 30 amps 12 wire is rated for 20 amps 12/2 is more than enough for 3500 watt/3800 watt elements. When you have 4500 or 5500 watt elements you must use10 wire/30 amp circuit. No exceptions on that spec. Nothing wrong with upsizing the wire as you describe. It wouldn’t be necessity to do so with the requirements needed with the water heater you are installing. An electrician would ask why bother. But the good thing in your changing of the wire would allow for a higher wattage heater to go in without doing anything other than switching the breaker to a double 30. Not an electrician but I’ve done a great deal of this in my day. A huge misconception people ″think″ they can increase the breaker size without increasing the gauge of the wire. Not a good thing and a fire/electrical hazard can follow.
Post Reply
 Re: wire size for50 gallon Rheem
Author: chip (OH) Ok,then i’ll leave the 20 amp breakers in their and run a new12-2 line from the heater to the box,a few years ago they made the romax coler coded is’nt14 yellow and12 orange? Thanx Chip
Post Reply
 Re: wire size for50 gallon Rheem
Author: packy (MA) i like dunbar’s advice of up-sizing the wire to a10. i believe10 is orange.
Post Reply
 Re: wire size for50 gallon Rheem
Author: ev607797 (NC) The Romex (NM-B cable) coloring is white jacket for14 cable, yellow for12 and orange for10.Larger sizes are usually black or gray, but there’s really no color standard for anything larger than10. The standard for water heater circuits is10, two conductors with ground (10/2) and a 30 amp circuit breaker for a water heater.If you are running cable anyway, just run10 and replace the breaker so it’s done right, once and for all.Unless you are installing a commercial unit, that’s all you will ever need to have in place in a residential environment. Remember that even though electric hot water heaters have two heating elements (upper and lower), they are NEVER operating at the same time.The upper thermostat functions to ″ping-pong″ the elements on and off. I once had a customer (when I was an electrician) demand that we provide a 50 amp circuit for an electric water heater to replace a propane one.His logic was that since there’s a potential 9,000 watt load (two elements), we must install a circuit that is prepared for it.After a few minutes of ″electric water heater 101″, he understood and we saved him a bunch of money. -Ed-
Post Reply
 Re: wire size for50 gallon Rheem
Author: hj (AZ) 10 would be adequate for almost any residential water heater, the gallonage is immaterial. However, most heaters you will find are going to be 4,500 watts. The lower wattage ones are not usually a normally stocked one, and could be called ″energy efficient″, but are really just slow heating ones.
Post Reply
 Re: wire size for50 gallon Rheem
Author: chip (OH) Thanks for all the info guys!I’ll let you know how it turned out. Chip
Post Reply
 Re: wire size for50 gallon Rheem
Author: Edward429451 (CO) What would be the reasoning for upgrading the wire size to10 and not going ahead and snapping in a twin 30 breaker? You may as well expect someone to put in a 4500W element when one of the originals go bad.
Post Reply
 Re: wire size for50 gallon Rheem
Author: hj (AZ) The only ″good″ reason would be if the heater has wires just adequate for the 3600 watt elements, in which case the 30 amp breakers would create an unsafe condition.
Post Reply
 Re: wire size for50 gallon Rheem
Author: chip (OH) the way it’s geared up now is12/2 twin 20 amp breakers which is adaqueate for the rheem tank i have with 3500 watt elements,if i do upgrade to10 wire than of course i would have to change the twin breakers from 20 amp to 30 amp because it could be a fire hazzard with10 on twin 20 amp breakers,now let’s say i remove the 12/2 cable and remove the twin 20 amp breakers and run a new10 wire to the box with new twin 30 amp breakers would that at all affect the elements being that they are only 3500 watt and not 4500 watt?
Post Reply
 Re: wire size for50 gallon Rheem
Author: hj (AZ) There is no ″fire hazard″ with10 wires and a 20 amp breaker. The fire hazard comes in when you have12 wires and a 30 amp breaker. The purpose of a circuit breaker is to protect the wires, and they dictate the maximum size breaker that can be used, not the other way around. With10 wires you can use ANY breaker up to 30 amps. The anomaly ia that the heater’s internal wiring, except for those with 5500 watt elements, is12 wiring.
Post Reply
 Re: wire size for50 gallon Rheem
Author: chip (OH) i misunderstood before i understand now thanx. Chip
Post Reply
 Re: wire size for50 gallon Rheem
Author: rhoskins (AL) My hot water heater will require 65 feet of cable.Is10 wire adequate for a 50 gal. Rheem so far from the main breaker box?
Post Reply
 Re: wire size for50 gallon Rheem
Author: eschat (FL) So are you saying that the wiring inside a 5500w tank is different than tanks with less wattage? I am planning to install a 5500w tank into a dbl 30 Amp Breaker using 10-2 wire with copper ground. Do I have it right to upgrade my wire 14-2 to the 10-2 size? Is that what I need to bring things up to code?
Post Reply
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What Are Some Basic Tips for Wiring Electric Water Heaters?

  1. In most locations, a permission is required for the installation of an electric water heater, regardless of whether the work is done by a professional or by a private citizen.
  2. As part of the permit procedure, an inspector will check the work to ensure that the electrical and plumbing connections are made properly and safely, and that the installation conforms with the requirements of the local building code.
  3. We will only look at the fundamental electrical needs for a regular tank-style electric water heater, not an on-demand (tankless) water heater, in this section.
  4. In the event that you want to replace an existing electric hot water heater, now is the time to check to see if the original water heater wiring is still in good working order.

Turning off the Power

  1. First, switch off the power to the circuit that feeds the water heater before you check or touch any of the wiring or electrical connections on the water heater itself.
  2. In the majority of circumstances, a 30-amp, double-pole circuit breaker is used to protect the circuit.
  3. Switch off the relevant breaker in the breaker box, and then test the circuit at the water heater using an electrical voltage tester to ensure that it is not still active on the circuit.

Locating the Electrical Connections

  1. When installing a water heater, the electrical connections are made at a junction box that is constructed into the water heater tank’s uppermost section.
  2. This is protected by a cover plate, which can be removed to allow you to see the wire connections on the interior of the enclosure.
  3. A flexible conduit or flexible metal cable, such as metal-clad (MC) cable, is typically used to encase the wire conductors running to the heater and protect them from damage.
  4. This flexibility gives a little amount of wiggle space, which makes it easier to repair the water heater, and it is a mandatory feature in many earthquake-prone locations, as well.
  5. You may check for power by holding a non-contact voltage tester near to the wire connections while the cover plate is removed; if the circuit has been correctly shut down, the tester will not light up.

Understanding Water Heater Wiring

  1. Electric water heaters necessitate the installation of a 240-volt dedicated circuit that serves only the water heater and none of the other appliances or devices on the circuit.
  2. In most cases, the circuit wiring will consist of a 30-amp double-pole breaker and 10-2 non-metallic (NM) or multi-conductor (MC) cable.
  3. If you have a black circuit wire, it should connect to the black wire lead on your water heater, and if you have a white circuit wire, it should link to either the red or white wire lead on your water heater.
  4. A piece of black or red electrical tape should be wrapped around the white circuit wire at the connection at both ends of the circuit (at the water heater and at the breaker box), to signal that it is a ″hot″ wire rather than a ″neutral.″ The live current in a 240-volt circuit is carried by both the black and white wires, in contrast to a normal 120-volt circuit.
  5. The circuit ground wire is connected to either the green ground screw on the water heater or the ground lead on the water heater, depending on which is appropriate.

Heating Element Wiring

  1. When replacing an electric water heater, you won’t have to deal with the thermostats or heating elements, but it’s important to know that elec

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