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How To Wire A Hot Water Heater


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Wiring a hot water heater is not as complex of a job as some people may think it is. In reality, the process is quite simple, and can be learned in no time.

Avoid the extra cost of hiring someone to do the job, when you can educate yourself, and find out how to get the job done right here!

Tools & Equipment Needed

Tools & Equipment Needed

The first thing to do before jumping into the thick of any job, is to make sure that you identify and gather all of the tools and equipment that you will need to get it done properly.

Here is a list of what you will need in order to wire a hot water heater correctly, efficiently and safely:

  • A screwdriver
  • A wrench
  • A pipe cutter/sander
  • Needle nose pliers
  • Dielectric connectors
  • Voltage testers
  • Flexible hosing
  • Sandpaper

Before You Start

Before you start on your water heater wiring DIY project, it is important that you purchase a water heater that can properly suit your household’s needs.

Consult your local household hardware and appliance dealer, or go online to find and compare all of the most popular models.

Another important thing to ask yourself before you get started is whether or not the power is currently running to the water heater. Make sure that there is a circuit breaker running a power line to your water heater so that when you do complete your wiring job everything will be ready to go!

One last thing to remember before getting started is that you should not fill your water heater’s tank up with water until everything is completely wired and closed off. 

You should also not be turning the circuit on until the tank is fully wire, and also full of water and ready to go. The heating element needs to be submerged in water or it could potentially break.

1.	Disconnect The Water Heater From The Power Source

Step-by-Step Guide

1. Disconnect The Water Heater From The Power Source

The first step is to make sure that there is no electric current or power supply running to the water heater before you do anything else.

Turn off the corresponding circuit breaker in order to be sure that there is no power being provided to the water heater.

You can use a voltage tester to check for any electric current that is still present.

2. Drain The Hot Water Tank

Your next step is to drain any hot water that is in the tank and in the pipes. Once the water starts to run cold, shut off the cold water supply as well.

Now, drain all of the cold water in the tank and leave it completely empty. You can connect a hose to the draining valve and have it run to an outside garden or reservoir for simplicity.

3. Disconnect Old Wiring & Remove Old Unit

Remove unit after disconnecting old wires

Now it is time to remove any electric wiring that remained from the old water heater. This ensures that you can safely and effectively remove the old unit, and also allows you to check for any wires that need to be replaced.

It is a good idea to label all of the wires as you disconnect them in order to make your reinstallation and wiring process as simple as possible.

Labeling, or even taking a picture, will help prevent the need to figure out where each wire belongs when wiring in the new water heater.

4. Disconnect The Piping

The next step is to disconnect the piping system from the old water heater tank setup. It is important to check to see if any of the pipes in use are made of copper - in which case they may need to be cut off.

Otherwise, using a wrench, remove the pipes connected to the tank. While doing this, be sure to check the condition of the pipes and see if there are any that need to be repaired or replaced.

Assuming all of the pipes are in working condition, you can save some money and reuse them when installing the new water heater unit.

5. Remove The Old Unit & Place The New One

testing new unit

Once you have disconnected all of the wiring and piping, and properly drained your hot water heater, it is time to install the new unit.

When the old unit has been removed, give that space a nice cleaning - clear any debris, clean out any dust and dirt, and make sure there is no obvious damage that needs to be attended to.

You may now place your new water heater into its space. At this point, you have the option of adding any elements that may help with installation or future maintenance.

One suggestion would be building a platform made out of building blocks to elevate the unit. Consider the height of the heater, as well as the piping and wiring while doing this!

6.Sand Down Copper Pipes

This step is only applicable for people who have copper piping that they will be using for installation.

Copper pipes will need to be properly sanded before they can be properly fitted into the new water heater unit. Sand the copper pipes until they are smooth, shining, and will be easily incorporated into the new set up.

7. Wire In Your New Water Heater

New heater wired

Now that your new water heater is in place, it is time to go about wiring it up properly.
First, start by accessing the wiring on the new water heater by removing the cover on the unit’s junction box.

Once you have located the wires inside the junction box on your new unit, you now need to remove the knockout panel. This can be done with a pair of needle nose pliers.

It is now time to refer to the labels you made earlier in Step 3, when you disconnected the wiring from the old water heater. Use the labels or the pictures you took to accurately connect your new water heater’s wiring to its power source.

A typical water heater will have a black wire, a red wire, and a green ground conductor wire. Some water heaters may be different than others, so it is recommended to consult the instructions/product manual provided by the manufacturer.

8.Finish Off Your Installation

Now that your new water heater has been wired correctly, all that is left to do is finish the installation by connecting the pipes, installing your temperature and pressure discharge valve and turning on the power!

This process is quite simple and can be done with the help of some informational articles or videos. You may also consult a professional and have them attend to this as well.

Safety Tips

The most important safety tip to consider when diving into a DIY water heater wiring project is to be wary of the potential for electrical shocks and injury.

In order to avoid this, ensure that there is no power running to the water heater before you do anything else. You can use a voltage meter to check for any live circuits.


In this article, we provided a step-by-step guide that goes over how to wire a hot water heater. The process is quite simple, but can still provide challenges and potential safety hazards.

If you are not comfortable with taking on a DIY hot water heater wiring project, consult a professional and have it done for you! Better safe than sorry.


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