What Size Wire For 220V Hot Water Heater

What Gauge of Wire is Used to Wire a 220-Volt Hot Water Heater?

In order to properly wire a hot water heater, it is necessary to adhere to the National Electrical Code, which defines the wire gauge size and circuit breaker size dependent on how much current the hot water heater draws.

Voltage Requirements

The majority of electric hot water heaters operate on alternating current (AC) voltages ranging from 220 to 250 volts. The hot water heaters require a double circuit breaker that is rated for the amperage draw of the hot water heaters in order to operate at this voltage in a residence.

Power Requirements

AC voltage ranges from 220 to 250 volts for most electric hot water heaters. The hot water heaters require a double circuit breaker with an amperage rating equal to or greater than the voltage in the residence.

Common Current and Wire Gauge Sizes

Installing a hot water heater requires the use of wire that is large enough to handle the current demand of the heater. Typical hot water heater sizes are as follows: a 20-amp hot water heater requires 12-gauge wire, a 25-amp hot water heater requires 10-gauge wire, and a 30- to 40-amp hot water heater requires 8-gauge wire. Because some big heaters can draw as much as 50 amps, 6-gauge wire is required.

What size wire is needed for electric water heater?

Current and wire gauge sizes that are commonly used Connect a hot water heater to a wire that is large enough to handle the heater’s current requirements. Typical hot water heater sizes are as follows: a 20-amp hot water heater requires 12-gauge wire, a 25-amp hot water heater necessitates 10-gauge wire, and a 30- to 40-amp hot water heater necessitates 8-gauge wire Electric hot water heaters normally need the installation of a dedicated 30-amp, 240-volt circuit breaker. In most cases, a 10/2 Romexcable will be used to deliver electricity from the breaker panel to your water heater (Blkwire -hot, Marked Whitewire-hot, Bare copperwire- ground).

  • A4500 watt element requires a 10/2 wire and a 30 amp (220volt) circuit breaker to be installed.
  • In addition to the size of wire mentioned above, what size wire do I require for a 50 gallon water heater?
  • If you’re going to run cable anyhow, simply run 10 and replace the breaker to make sure it’s done correctly the first time.
  • The majority of 50 amp water heaters will have components that are 4500 watts.

How to Wire a 220V Hot Water Heater

Home-Electrical An untrained homeowner may find working with electrical wires intimidating and potentially hazardous. Before doing any home electrical repair, consult the owner’s handbook for your hot water heater and educate yourself on the fundamentals of electrical wiring. if (sources.length) then this.parentNode.removeChild(sources); then this.onerror = null; this.src = fallback; )(, arguments.target.currentSrc.replace; )(, arguments.target.currentSrc.replace; )(, arguments.target.currentSrc.replace; (//$/, “), ‘/public/images/logo-fallback.png’) (//$/, “), ‘/public/images/logo-fallback.png’) ” loading=”lazy”> ” loading=”lazy”> How to Connect a 220V Hot Water Heater to the Electrical System Wiring a 220V hot water heater is not something that the average homeowner should do unless they have prior professional training or knowledge.

An electric water heater is frequently a large and sophisticated item that, if not installed properly, can be hazardous to your health and safety.

When wiring, make sure to take your time, double-check your work, and enlist the help of a friend or family member. Extra eyes (or two) on the job site might be the difference between a good installation and a potentially unsafe scenario.

  • Voltage testers that do not require touch
  • Wire strippers Twist-on wire connections
  • Electrical tape
  • And other supplies

220 Volt or 240 Volt?

One thing you might note is that the terms 220V, 230V, and 240V connections are often used interchangeably in numerous manuals, which is a good thing. As previously stated, electrical service is given in levels of 120 or 240 volts per electrical box/outlet, but values such as 220 and 230V are related to the design of appliances or equipment. Even if an appliance is meant to operate on 220, 230, or 240 volts, it will still require that it be connected to a 240V electrical current.

Basic Home Wiring

One thing you might note is that the terms 220V, 230V, and 240V connections are often used interchangeably in numerous manuals, especially in the construction industry. As previously stated, electrical service is given in levels of 120 or 240 volts per electrical box/outlet, but values such as 220 and 230V are related to the design of appliances and equipment. If you want to utilize a device that is meant to operate on 220/230/240 volts, you’ll still have to connect it to a 240V electrical current.

  • A black wire is known as the “hot wire,” and it is responsible for transporting current from the fuse box to the fixture. A red wire is yet another “hot wire” that is responsible for carrying the electricity. As a result of the fact that one hot wire has a negative charge and the second hot wire has a positive charge, when two hot wires are utilized, the circuit is completed. A bare copper wire serves as the “ground,” which helps to keep the circuit grounded for safety.

In order to create a straight 240-volt current, electric hot water heaters just require those three wires. Some 240V appliances necessitate the use of a fourth “neutral” wire, which is often painted white. This is only required to power any additional accessories to an item that operates on 120V rather than 240V, such as the lights and timers on an electric range. 240V is not required for most appliances. Even if your electric water heater should not require the connection of the white wire, it is always a good idea to check the heater’s handbook to make sure.

Electric Water Heater Installation

When it comes to bringing a new appliance into your house, the best place to start is by reading through its instruction manual and looking through any online resources supplied by the manufacturer of the item. While there are certain basic guidelines to follow when installing a typical hot water heater, the following are the most important:

Shut Off the Power

  • However, even though it appears to be an apparent step, it cannot be neglected. When installing a hot water heater, the fuse box is frequently out of sight line, so make careful to cut off the relevant circuit and post a message on the box explaining what you did and asking people to leave the box alone while you work. After you’ve turned off the electricity, use a noncontact voltage tester to make sure the cable is no longer hot before continuing. As long as the voltage tester is still picking up energy, it is recommended that you return to the fuse box to double-check the circuit that you previously shut down. Before handling any cables or wires, make absolutely certain that the electricity has been turned off.


Remember to turn off all power to the circuit you’re working on to avoid electrocuting yourself or others.

Connect the Wires

  • The junction box for your hot water heater is normally placed on the top of the hot water heater, so search around until you find it. Following the opening of the junction box, you’ll see that it either retains the wires individually or in a cable
  • Thus, take the time to identify the black “hot” wire, the red “hot” wire, and the copper ground wire before proceeding. Some of these appliances have three wires, but one of the “hot” wires is white rather than red, which indicates that the device is not grounded. If this is the case, wrap a strip of electrical tape around the wire’s plastic coating to indicate to a future electrician that the cable is “hot.” The NM cable may be found in a wall, and with wire strippers, you can remove the outer layer of cable to reveal the three wires within. In this case, the ground wire should be a bare copper wire, but the other two will need to have their wire ends opened up so that the copper ends of all three cables can be seen. Inspect the hot water heater’s wiring to ensure that it has been done in the same manner. Match up each wire with its corresponding wire once you’ve stripped away the plastic covering from it. For example, match the color of the wire to the color of the wire it’s related to: black with black, red with red, naked with bare, and so on. Connect the copper ends of each matching wire together with a twist-on wire connector, and then tape each connection with electrical tape to keep it from separating.

Check the Connection

  • Reinstall the top of the heater’s junction box and switch on the live circuit to the heater once each wire has been securely fastened together. Examine each wire with your noncontact voltage tester, making sure that the “hot” wires are functioning as intended. If there is a problem with one of the connections, switch off the power and make the necessary changes.


  1. Whenever in doubt, seek the advice of an electrician with any queries or concerns

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,

Amperage Wire Size
20A 12 Gauge
25A 10 Gauge
30A 8 Gauge
50A 8 Gauge
60A 6 Gauge

When it comes to wattage,

Watt Wire Size
2000W 10 Gauge
2500W 8 Gauge
3000W 6 Gauge
3500W 6 Gauge
3800W 4 Gauge
4500W 4 Gauge
4800W 3 Gauge
3KW 6 Gauge

The voltage used in this computation is 120V. in gallons per gallon

Gallon Wire Size
30 Gallon 12 Gauge
40 Gallon 12 Gauge
50 Gallon 6 Gauge
80 Gallon 6 Gauge

This calculation is based on the following information: 240VWire Size For Tankless Water Heating

Watt Wire Size
7600W 4 Gauge
9600W 3 Gauge
11500W 2 Gauge
13400W 1 Gauge

This computation is based on a 240V power supply. 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?

The amperage is required in order to compute the correct wire size. Consider the following scenario: you have a 3,000W heater that operates on 120V.

Following the 80 percent rule, the amperage is calculated as (3000/120)*80 percent, which results in a total of 45 amps. According to the amperage table, 8 gauge wire is the ideal wire size for a 3000W heater. 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

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. 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. The size of the breaker, on the other hand, is equally significant. 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.

  • It is critical to consider the size of the 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.
  • When choosing a breaker, try for a size that is as near as possible to 31 amps in rating.
  • Because of this, a 25A water heater requires a 35A breaker to be installed.
See also:  What Is The Best Water Filter For Sink

4). Gallons

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. Moreover, you are aware that many contractors utilize gallons to calculate the appropriate wire size. A 40-gallon heater necessitates the use of 12-gauge wiring. A 50-gallon water heater, on the other hand, necessitates the use of 6-gauge cable. The thicker the wire is proportional to the size of the tank, just as it is proportional to the amperage rating.

In fact, if your heater includes a label that indicates its wattage, you may disregard the gallons of water it uses.

Consequently, you have an amp rating of 18.75.

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. Posts Related To This:

  • Thermoelectric Water Heater (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?

A water heater necessitates the use of three wires: a black wire, a white wire, and an earth wire. The white and black wires of a 10-2 ground shielded cable serve as hot conductors in this configuration. The neutral wire will be connected to the ground wire. 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?

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

  1. Taking the example of wire gauge, a 6-gauge wire is thicker than a 10-gauge wire.
  2. It is preferable to utilize larger cables than it is to use smaller wires.
  3. The expense, on the other hand, is expected to climb.
  4. 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.

  • The first thing to mention is that cable and plug water heaters are extremely widespread. It is dependent on your geographical location. In addition, they are often smaller and less powerful
  • Third, the power cables of the chord and plug water heaters are fitted at the factory by the manufacturer. 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) Fixed-storage water heaters are classified as continuous loads under the National Electrical Code. It is necessary to have temperature-limiting functions in the controls. 3). According to the National Electrical Contractors Association, the circuit rating should be at least 125 percent of the heater’s amp rating. 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?

There is nothing wrong with utilizing 12/2 wires in your installation. However, I recommend that you utilize 10/2 wires. 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. 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 Size Wire for a 40-Gallon Electric Water Heater? [Explained]

It is possible that we will receive commissions for purchases made through the links in this post. It is critical to determine the optimal size of wires for a 40-gallon electric water heater before installing them. Short circuits can occur when cables are not properly matched. You don’t want to be in that situation, do you? What size wire should be used for a 40-gallon electric water heater is the subject at hand. The wire gauge required for a typical 40-gallon electric water heater is 12 gauge.

The current will exceed its capacity, and the wire will begin to melt.

Discover what factors we should take into consideration while selecting a heater wire.

Why The Sizes of Wires Vary in Different Water Heaters?

Water heaters are available in a variety of sizes and capacities. Wire sizes vary depending on the size of gallons used in each application. The recommended wire size for a 40-gallon electric water heater, for example, is 12 gauge wire. Electric water heaters with a capacity of 50 gallons require wire with a gauge of 6. The gallon size is proportional to the size of the wire. It is also possible that the wiring will differ depending on whether the water heater is mounted vertically or horizontally.

For example, the recommended wire size for a 20-amp hot water heater is 12-gauge wire.

How to Calculate A 40 Gallon Water Heaters Wire Size

When it comes to a 40-gallon heater, you can’t just pick any wire size anymore. To begin, you must gather data in order to be able to quantify it. As an example:

  • The kind of wire (copper or aluminum)
  • The phase of the circuit
  • The voltage of the circuit
  • One-half of the entire circuit length
  • And the total circuit amperage

An typical 40-gallon electric water heater operates at 240 volts and 2500 watts, according to the manufacturer. As a result, by dividing the amperage by 240, we can determine that the amperage is 18.75 amps. It may be approximated as 20 A by using a calculator. Approximately one-half of the overall circuit is 80 meters in length, with a single phase of circuit operation. You may now use a calculator to determine the size of a 40-gallon wire. As a result, you may use a copper wire of 12 gauge for this project.

Using the approach outlined above, you can determine the wire size required for your heater. Want to know how to choose the best wire to use in an electric heater? Congratulations, you’re on the right route! For your consideration, we offer the following suggestions:

So now that you have your wire, let’s have a look at why it’s so vital to have the proper length of wire.

Why Matching The Wire Gauge Is Important For An Electric Heater

If you’re replacing the wires for your heater, you should be aware of the importance of matching the wires correctly. It lessens the likelihood of the wire being heated. Short circuits, on the other hand, will result if you utilize wire that is not matched. How? Suppose you’re utilizing a 40-gallon water heater on a 30-amp circuit with 6-gauge wire. Here’s why: A heater operating at 220 volts generates more current than the circuits can handle. It begins to melt the items in its immediate vicinity, just as when your shower cable warms up!

One miscalculation might possibly result in the death of someone.

Things to Keep in Mind While Replacing Wires of An Electric Heater

You must first get a permit before performing any work on your water heater wiring. An inspector examines the electrical and plumbing connections to see if they are properly linked or not. To replace the wire, you must first read and understand the installation instructions.

  • The circuit wire is included, as is a double-pole breaker with a 40-amp rating. It also contains 10-2 non-metallic (NM) cables
  • The black circuit wire should be connected to the lead of the black wire in order to complete the circuit. The white circuit wire should be used to connect the lead of the red or white wire
  • The white circuit wire should be wrapped with black or red electrical tape at the breaker box. It serves to distinguish between which wire is considered to be “hot” and which is considered to be “neutral.” A 240-volt circuit allows electricity to flow via both wires (black and white). Connections should be made by connecting the circuit ground wire to the green ground screw on the water heater

Quick Tip: Make certain that you are using the correct size circuit breaker, otherwise your heater will be damaged. If everything else fails, a professional technician should be contacted to resolve the issue.


Is it possible for me to replace my hot water heater myself? Answer: You can replace a hot water heater on your own if you have some prior knowledge in the field. However, no matter how much experience you have, you must first obtain authorization to do so. Also, before you replace them, make sure you know what to do and what not to do. Is it possible to use a 40A circuit breaker on a 10 gauge wire? Answer: It is not possible to install a 40A breaker on a 10 gauge cable. For a 40A circuit breaker, you’ll need to utilize wire that’s 8 gauge or smaller.

See also:  What To Set Water Heater To

The answer is 4500 watts divided by the number of amps.

This is for a 240-volt electric circuit.

Bottom Line

That’s all there is to it! You can now determine the size of the wire needed for a 40-gallon electric water heater by measuring it. If you wish to change the wires in your heater, you should follow the directions in this page. That’s all there is to it for today! I hope we’ve cleared up any ambiguity about what has to be done. Until then, keep yourself safe and sound! Hello, my name is Melissa and I’m writing from Illinois, United States. I’ve been in the furnace operator and tender industry for a number of years now, and I’m passionate about making people’s lives more comfortable in their own residences.

wire size for 50 gallon Rheem

Over 680,000 strictly plumbing related postsWelcome to Plbg.com the PlumbingForum.com. We are the best online (strictly) PLUMBING advice, help, dyi, educational, and informational plumbing forum. Questions and discussions about toilets, sinks, faucets, drainage, venting, water heating, showers, pumps, and other exclusively PLUMBING related issues.Please refrain from asking or discussing legal questions, pricing, where to purchase a product, or any business issues, or for contractor referrals, or any other questions or issues not specifically related to plumbing.Keep all posts positive and absolutely no advertising. Our site is completely free, without ads or pop-ups. We do not sell your information. We are made possible by:
wire size for50 gallon Rheem
Author:chip (OH)would10 wire be safe for a 50 gallon rheem240 volt water heater with 3500 watt elementson 2 20 amp breakers?the romax is currently12-2 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?thanxChip
Post Reply
Re: wire size for50 gallon Rheem
Author:Dunbar (KY)10 wire is rated for 30 amps12 wire is rated for 20 amps12/2 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 theirand 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?ThanxChip
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 youknow 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 20amp breakers which is adaqueate for the rheemtank 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
  • Messages that are inappropriate or that are obvious advertisements will be removed. Unfortunately, we cannot be held liable for incorrect or insufficient advise
  • Furthermore, Plbg.com has no control over external content that may be linked to from messages placed on this site. Please use caution when clicking on external links
  • Plbg.com is strictly for the exchange of plumbing-related advice and NOT for questions about pricing or costs, where to find a product (try Google), how to operate or promote a business, or questions about ethics (law) and the like
  • Plbg.com is also not a place to ask questions about radiant heating (try HeatingHelp.com), electrical, or even general construction type questions
  • Plbg.com is strictly for the exchange of plumbing-related advice and NOT We are only here to answer plumbing-related questions.
Search for plumbing parts on our sponsor’s site:

Special thanks to our sponsor:

What Size Breaker Does a Water Heater Need?

Circuit breakers are required for the operation of your electric water heater and gas tankless water heater. Choosing the incorrect size circuit breaker, on the other hand, might result in poor safety and even damage to the water heater. 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. Circuit breakers and wiring for electrical safety are specified in the National Electrical Code, which defines rules for their sizing and installation.

  • 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.
  • This indicates that the breaker only provides power to the water heater and does not provide power to other appliances.
  • On occasion, I’ll come upon a 4500-watt water heater that has a 20-amp circuitbreaker.
  • 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. 240-volt circuit breakers are required for a water heater that has a 4500-watt heating element. A 10/2 wire is required for this water heater. With a smaller 12/2 cable and a 20 amp circuit breaker, the 3800-watt heating element may be connected to the rest of the system.

Sizing Water Heater Breakers

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

Element Watts Breaker Size 120v Breaker Size 220v Wire Gauge
1500 15 amp 15 amp 14
2000 20 amp 15 amp 14
2500 30 amp 15 amp 14
3000 30 amp 15 amp 12
3500 NA 20 amp 12
4000 NA 25 amp 10
4500 NA 30 amp 10
5000 NA 30 amp 10
5500 NA 40 amp 8

How Do You Calculate Breaker Sizing?

The power and voltage ratings of your water heater should be checked. The wattage and voltage rating of a water heater are labeled on a sticker that is attached to the thermostat panel. This information may be found around the base of certain heaters. While the majority of household water heaters have a capacity of 4500 watts or less, commercial water heaters can exceed 5500 watts or more. Let’s get down to the nitty gritty of determining the breaker sizes. 4500 divided by 240 equals 18.75 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.
  • As a result, multiply 18.75 by 125 percent to account for the fact that a water heater operates on a continuous load.
  • When we round that value down to the next tenth, we obtain 25 amp.
  • It is commonly utilized because the minimum rating of 220 volts is greater than the 25 amp rating of the 25 amp breaker.
  • 20.45 amps multiplied by 125 percent equals 25.568 amps, which is rounded to 30 amps.
  • After all, it’s closer to 18.75 than 18.75.
  • 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.

What Size Circuit Breaker for Gas Tankless Water Heaters?

Compared to electric tank water heaters, gas tankless water heaters consume less electricity and produce less voltage. Typically, it’s around 12 amps and less than 120 volts in voltage. In order to power the electronic ignition system on gas tankless water heaters, a little quantity of electricity is required. 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?

This decision is based on your geographic location as well as the utility costs in your region. Gas water heaters, on the other hand, are often more expensive to purchase up front but less expensive to operate than electric water heaters. In contrast to gas water heaters, electric water heaters are more energy efficient than their gas counterparts. The cost of gas is 40 percent more than the cost of electricity. 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.

If you want to make changes to your home in order to accommodate electric, gas, or tankless water heating systems, you should consult with a specialist.

Before beginning any job, you should contact with a competent expert and verify that all necessary permits have been obtained.

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 wire is used for electric water heater?

This decision is influenced by your geographic location as well as the utility costs in your neighborhood. Although gas water heaters are often more expensive to purchase up front, they are typically less expensive to operate over time. However, electric water heaters are more energy efficient than gas water heaters, which is a plus. When compared to electricity, gas is 40 percent less expensive. As a result, using gas would be more cost-effective. Electric water heaters, on the other hand, are more cost-effective when you consider the time savings over time.

Consider hiring an expert if you plan on making changes to your home to accommodate electric, natural gas, or tankless water heaters.

Before beginning any job, it is recommended that you speak with a competent expert and check local permission requirements.

HomeInspectionInsider.com is also a participant in affiliate marketing programs with other web sites that promote home inspection services.

Color code for residential wire/ how to match wire size and circuit breaker

Use only 600 volt wire.Lamp cord, extension cords are not rated 600 volt.Use copper wire only. Aluminum wire is fire risk and should be avoided or installed by professional.30 amp breaker use 10 gauge / 120-240 volt 30 amp outlet can be installed on 30 amp breaker only/ use 10 gauge wire. cannot be connected to 15-20-40 amp breaker.Orange/10 gauge wire, with ground. 30 amp capacity. Safe maximum: 30 x 80% = 24 amps.Buy:10-2 gauge/ 30 amp10-3/ 30 ampSouthwire electric tools Yellow 12 gauge 20 amp 120 volt 20 amp outlet can be installed on 20 amp breaker, but not 15 amp breaker/ use 12 ga wire.

cannot be connected to 30-40 amp breaker.

20 amp capacity.

Never connect 15 gauge wire to 20-30-40 amp breaker.White/14 gauge wire,with ground.

Safe maximum 12 amps.Buy:14-2 gauge/ 15 amp14-3/ 15 ampNMB is house wiringUF is underground 50-60 amp breaker use 6 gauge / 240 volt 50 outlet can be installed on 50 amp breaker onlyBuy:6-2 wireSouthwire electric tools NMB is house wiringUF is underground 40-50 amp breaker use 8 gauge / 240 volt 40 amp outlet can be installed on 40 or 50 amp breaker onlyBuy:8-2 wireSouthwire electric tools NMB is house wiringUF is underground Copper ground wire.

Every device, load, metal enclosure etc must be grounded.

use same size as other wire in circuitBuy:12 gauge copper ground wireGround wireGreen ground wireGround pigtailsGround rods/ ground clamps at Amazon Non metallic flexible cablesmust carry ground wire, but do not have hazard of short circuit causing injury from shock.Armored steel cablecan be used as a grounded connection, and will protect wires from damage.

  1. flexible and rigid.
  2. Movement, damage and deterioration are major cause of electrical failure.Buy:Non-metallic flexible conduitPower whipArmored cableSouthwire armored cable cutterPull boxes Electrical tools must be insulated.
  3. even when breaker is off.Buy:Electrician tools kitsKLEIN TOOLSTools kitsIRWIN toolsKNIPEXTelephone cable knifeLow Voltage Mounting Bracket for Telephone 600 volt 12 ga Stranded wireot THHN wire is good for conduit with multiple wires.
  4. of heat causing splayed strands.that come loose.
  5. Connect stranded to short piece of solid copper wire, and attach solid to screw terminal.
  6. Only wire maked 600 volt can be used for permanent household wiring.Buy:Southwire 600 volt stranded wireRolls of stranded wireHOOK UP Wires Protect wiring from damage Use nipper instead of pliers or screwdriver for removing staples (and nails).
  7. NEC sec.
  8. Doing so increases resistance and heat on wire and creates possible weak point.Buy tools:KLEIN TOOLSWire strippers at AmazonElectric Wire Stripping MachineLinesman pliersUtility knife at Amazon Multimeters Voltage is tested across two separate wires.

Amperage is tested along one or two points on same wire.Buy:Analog multimeterMultimeters at AmazonKlein multimeterElectric testers at AmazonClampmeter for testing amp flow on line Household NM-B Wires are color-coded so inspectors/ electricians can easily identify which wire is used during constructionDamp- wet locations:For direct burial underfoot, in contact with damp soil.

or for other damp locations.

or use plastic conduit.

Using sharp blade on utility knife, push blade into end of grey cable sheathing next to ground wire.

After cutting into sheathing 3-4,” you can gently strip grey cable sheathing from around the black and white wires, being careful not to damage insulation. Match wire size and breaker amp rating If your home was wired by professional electrician who pulled permits, then circuit breaker and wire size will match.

  • Add up total watt load on circuit.
  • fire danger Breaker can let the voltage push too much amperage (current of electrons) through the matrix (atomic structure) of the wire.
  • Absolute electrocution danger when removing cover off main panel.
  • 120 volt: use a single breaker or tandem breaker.

Code says: Use connected/ double-pole breakerAgainst code: Use 2 single breakers to supply 240 volt, unless the switches are connected and each rated for same ampsIf double breaker is rated for 30 amp, then BOTH sides of the breaker are each 30 amp (not 15 amp each) Power is doubled with 240 volt vs 120 volt, amps are not halvedResource:How to replace circuit breaker3-phase wiringAre both sides of 30 amp double breaker 30 amp? Circuit breaker and wire size must match Chart on left shows that 30 amp breaker matches 10 gauge copper wire.Do not use aluminum wire.

  • Copper wire is safe.
  • Aluminum wire expands more than copper wire.
  • Warm wires mean amp loss and potential fire hazard.
  • 14 gauge extension cord, frequently used for power tool cord, is rated 10 amps.Never use extension cord in place of house wiring.
  • Extension cords are made for plug ends, and have stranded wire instead of solid wire.

or it creates fire hazard.Cords should not be warm if they are used full-timeIf you are using extension cord as full time source of electricity for pump or fan, the cord should not be warm or hot If toaster oven cord gets warm when used, then that is normalIf you operate the appliance full time, then upgrade to larger cordBuy12 gauge extension cord’Flexible cords and cables may not be used:a.

Where run through holes in walls, ceilings, or floors; c.

Where attached to building surfaces; ore.


Circuit breaker resourcesWater heater is tripping breakerHow to replace circuit breakerHow to wire gfciCan AC breaker be used for DC breakerHow to reset circuit breakerNot enough space for circuit breakers/ use tandemCircuit breakersHow to install subpanelWhy you need ground wireSee inside breaker boxHow to wire safety switchHow to wire whole house surge protectorFigure volts amps and wattsFigure correct wire and breakerTypes of surge protection Multimeter Test for breaks in wire/ Test for voltageMost appliance require 80% rated voltage to function correctlyBuyAnalog multimeterMultimeters at AmazonKlein multimeterElectric testers at AmazonClampmeter for testing amp flow on lineResource:How to test and replace elementHow to test thermocoupleElement tests for 120 voltsHow to test wire Safety when testing wires:Never touch wet or previously flooded appliance.Never stand on wet surface when working on electric.Never stand on bare soil, put down dry boards.Tape tester leads to wood sticks to keep hands away from power.Use non-contact voltage tester before touching wires.Never touch or lean into any made of metal.Remove metal objects from pockets.Do not use oxygen or fuel accelerants in same room as electrical repairsResource:Basic house wiring Non-contact voltage tester Test for power without touching connectorsNEVER assume power is OFFBuy:Non-contact voltage tester AmazonElectric testers at AmazonResource:How to test electric power is off 120volt15 amp devices including GFCI, timers, switches, plugs, wifi controls etc can be installed on 15 or 20 amp breaker.120 voltGFCI, outlet, receptacle that is rated 20 amp can be installed on 20 amp breaker only, but NOT on 15 amp breaker.Buy15 amp GFCI20 amp GFCI BuyBasic electric bookHome plumbing/ electrical codesOr learn about basic household electricity.use and search my site/ResourceSafe electric wiringBasic house wiring Use outlet tester to check for correct wiring on any 120 volt straight-blade outlet.Buy:Klein testersOutlet testerCircuit breaker finderElectric usage monitor Non metallic flexible cablesmust carry ground wire, but do not have hazard of short circuit causing injury from shock.Armored steel cablecan be used as a grounded connection, and will protect wires from damage.

Metal can be energized from an insulation failure.All conduit.metal, plastic.

must be attached to structure, and attached to enclosures, boxes.

Always best to disconnect power, but insulation failure, lack of proper grounding, grounded neutral, lack of GFCI, out-of-code wiring, generator operating without transfer switch, and other problems still pose a risk to anyone working on electric power.

Do not use stranded wire or extension cord.Do not use solder anywhere on residential 120-240 volt wiring.

Tighten screws very tight against wire.Buy:NEC booksDewalt plumbing/ electrical codesBasic electric bookNational electric code guide/ illustratedResources:How to twist wire How to select and install twist-on wire connectors Weatherproof lever switch on outdoor lights Safely operate outdoor toggle switchReplaces outdoor coverInstall over top of ordinary switch Works with single-pole, double-pole, 3PST, 3-way, 4-way switches etcUse weatherproof box for outdoorCan be used indoor or outdoorBuy:Best choice: Cantex lever switchOutdoor lever switches at AmazonLever switchesResourceCantex-toggle-switch-covers.pdfCantex-PVC-junction-boxes.pdf


Buy:Crimping tool kitBlue for 16-14 wireYellow for 12-10 wireRatcheting CrimperResource:How to install terminal

Push-on wire connectors in place of twist-on connectors

Buy:Push on wire connectors AmazonRed 3P connector for 10-14 gauge wireLever connectors for stranded wire at Amazon Use nipper instead of pliers or screwdriver for removing staples (and nails). Do not damage cable or wires inside cable.Code -Cable SHALL BE secured without damage to the outer covering. NEC sec. 336-15BuyEnd cutting nippers at Amazon When removing insulation from wire, do NOT score or put cuts on surface of copper wire. Doing so increases resistances on wire and creates weak point.Buy tools:Wire strippers at AmazonLinesman pliersPro linesman plierNeedle nose pliersEnd cutting nippers at Amazon 6″ Pull box Junction boxes for conduit and wiringBuy:Bud industries 6x6x4 best value/ no KORaco 6x6x4 metal pull boxWiegman 6x6x4 pull boxHoffman 6x6x4 pull boxAdamax raintight enclosureRaintight 6x6x4 boxPull boxesBuy:Pull boxesPolycarbonite boxesResource:Enclosures and boxes

Leave a Reply

Your email address will not be published.