Why would wiring an electric water heater be something you would even think about attempting? To troubleshoot an electric water heater, you need to understand how the wiring works. There are safety concerns to be aware of. Are you willing to take a little time and become familiar with this type of problem? Will you follow the safety guidelines? This information will help you by providing a general knowledge of your electric water heater.

Did you answer yes to the two questions above? Yes, then you are allowed to continue reading. Safety when it comes to an electrical repair cannot be stressed enough. Serious injury and even death can result from an electrical shock. I am not even thinking about inserting something humorous here. Electric hot water heaters use 240 volt with significant amperage. More than enough to kill someone. Are you sufficiently afraid, actually respect is the correct word. You always need to have a respect for electricity when you work around it.

After this second warning are you still willing to proceed? Did you answer yes? How about a third warning, never touch anything on your hot water heater unless you are absolutely sure that the power is off. Use a tester to make sure.

Using Common Sense Header

What Can You Save?

Getting someone to come out to your home involves the proverbial 'service call'. This the fee that you pay for the privilege of meeting the serviceman. Prices vary, but the is usually $50 to $85. For a simple problem this will take care of it. With a water heater you may be faced with up selling. "Yes, i can fix it, but it may not last" might be the comment. Suddenly you are faced with a replacement project, maybe $500 to a $1,000. Whoa, at least make yourself familiar with your situation before you proceed. Make the repairman describe exactly what the problem is. Be armed with good questions.


How Hard Could It Be?

Wiring an electric water heater is an above average repair task. You have both skill issues and safety issues.

These repairs will have a Difficulty Level of: Difficult
These repairs require a Skill Level of: Home Repairman

For and explanation of the terms in this section, see How to Use This Site.

Check the Simple Things!

Check the breaker. No hot water? Is the breaker tripped? Unfortunately, a tripped breaker may be indicative of a more serious problem. Electric hot water heaters also have reset buttons (see below). Again bad news, if the reset trips it usually means something more serious is wrong.

What Can Go Wrong?

Did you read the beginning of this article? You have some very serious power going through your electric water heater. Be safe, take precautions. Water is also involved. Draining down a tank or flushing a tank will involve water, be prepared.

Understanding Electric Water Heater Wiring

Most hot water heaters are on a 30 amp two pole breaker. The two poles means it is a stated 240 volts or an actual 230 volts. As long as your water heater is not too far from the panel it will be wired with #10 wire. This is the common format for wiring an electric water heater, but it is not the only one.

Some newer two element tanks give you an option for simultaneous operation. What? In years gone by most electric water heaters with two elements were factory wired so that only one element would heat at a time. The upper thermostat would keep track of this, only allowing the lower element to heat when the upper one was finished. This is why electric water heaters have a longer recovery time than gas.

Now there is the option of wiring a hot water heater so the both elements run at the same time. This reduces the recovery time and will provide more hot water. The trade off it that it uses more amps and requires heavier wire.

Wiring an electric water heater with simultaneous element operation will mean a 45 Amp breaker and #6 wire. In a house that was wired any length of time back you probably don't have the right wiring for this configuration, even if you get a new hot water tank. You always want to check local codes before modifying any wiring in your home.

Hooking up the Wires

So how many wires do you get anyway? Wiring an electric water heater does not require that you use a plug in device. Therefore an extra conductor is not required. Most water heaters are wired with 10-2 w/Ground shielded cable. For long distances you may need to go with heavier wire. When you use this type of wire both the white and the black will serve as hot conductors. The bare ground wire will also be connected to the neutral lug.

Shielded metallic cable should be used from the water heater to the wall or ceiling. There will be an adapter connected to the top of the tank and the shielded cable will continue until it is out of the area where the wiring might be damaged.

You may find that a cable with an extra conductor has been used. This would be 10-3 w/Ground. In this case the red and the black wire will be used as the hot leads. You now have an redundancy with the ground and the white wire. The white wire is not needed. The long and the short of this story is that a water heater needs two hot conductors and a ground to work.

I have not mentioned 120 volt electric water heaters up to this point. For a residence they are highly impractical. They cost a lot to run and will not produce enough hot water to satisfy the needs of a home.

Checking for Power

The first thing you want to do is make sure that you are getting power to your electric water heater. See if the breaker has been tripped in the panel. Has it tripped? Yes, this is sort of good news. Reset the breaker and see if it holds. This could be a sign of another problem.

The next logical step would be to see if you have power to the water heater. The wiring is located on the top of the water heater. Before you take the cover off, shut the power off. Make sure that the power is off with the non contact voltage tester. Separate the wires enough to test the individual conductors.

Turn the power back on and use a non-contact tester to see if you are getting power to the water heater. The indicator light should light up when you are near a hot conductor. You should have two hot conductors coming into your electric water heater.

WARNING!! Make Sure the Power is OFF!!! BEFORE You Work on Electrical Devices!!!

Checking the Reset Button

There are two covers on the side of your electric hot water tank. Wiring and electric hot water heater also includes the high limit reset buttons. When they trip the water will not heat up.

The first thing you do is to shut off the power. After that there are two covers on the side of the hot water tank. Remove the covers, the insulation and the plastic shields. Make sure the power is off by using a working voltage tester. The upper and possibly the lower thermostats will have a red reset button. They pop out when they trip.

After you reset them you can put the covers on and turn on the power. If they keep tripping, something else is wrong, either with the thermostats or the elements. See Hot Water Heater Element Testing for information on how to check the components.

Checking the Heating Elements

The water heater elements do the actual work of heating the water. You likely have two of them. They are also the likely candidate when troubles arise. One or both elements can go bad. When the upper element goes bad you have no hot water. When the lower element fails you will have minimal hot water. So the elements are a big part of wiring an electric water heater.

You can use a simple test to tell if the elements are bad. See the article Hot Water Heater Element Testing for instructions on how to check them. The article Repairing Hot Water Heater Elements has information on replacing them.

Sediment build up can cause the lower element to fail repeatedly. See Hot Water Heater Sediment for information on build up in your water tank.

Checking the Thermostats

Wiring an electric water heater also includes the thermostats. The thermostats tell the elements when to heat up. Most residential water heaters have an upper and a lower thermostat. These are usually set up for non-simultaneous operation. Meaning that only one element is allowed to heat at a time. The upper thermostat acts as the controller, allowing first the upper element to heat and then the lower element.

A bad upper thermostat will mean no hot water at all. When the lower thermostat acts up you will have hot water, just not very much. The upper thermostat will always have a reset button. Sometimes the lower one will have one to. This is a red button that pops when the thermostat overheats.

The thermostats also have temperature settings on them. Hot water heaters are set at the factory to 120 degrees. Any hotter than that and you run the risk of serious burns. Homes with elderly, handicapped or children should not have the temperature set above this level.

To find out if your thermostats are bad, you need to test them. See the article Hot Water Heater Element Testing for instructions on how to test them. For instructions on replacing the thermostats, see Repairing Electric Water Heater Thermostats for all the information you need.

Wiring an Electric Water Heater Summary

Were you able to figure out what your problem is? Wiring an electric water heater involves several electrical components. Since you have so many items involved it takes some investigating to locate your problem.

In this article you found some general information about how an electric hot water heater works. It could be that your problem was in the wiring. You were also directed to other resources that discuss the various components. The hot water heater elements are the hands down winners for be troublesome. Your wiring an electric water heater problem may have involved changing the elements. Hopefully you have found your problem and are now enjoying plenty of hot water.

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