How To Hook Up Hot Water Heater To A Generator

Last Updated on September 28, 2023 by kiezelamquiz

a hot water heater connected to a generator, there's text at the lower left section that reads "How To Hook Up Hot Water Heater To A Generator"

Do you enjoy a soothing, hot shower even when the power goes out? Whether it’s for showers or washing dishes, access to hot water has become an essential part of our daily routines. However, disruptions in power supply, such as during storms, hurricanes, or outages, can leave us without this luxury. Learning how to hook up hot water heater to a generator can ensure you get continuous hot water supply, even when the grid goes dark.

To hook up hot water heater to a generator, ensure the generator’s wattage exceeds the heater’s requirements, install a transfer switch or interlock kit to link the generator safely, establish a dedicated circuit for the heater within the switch or panel, and securely connect the generator and heater wiring. 

In this guide, we will take you through the step-by-step process of effectively hooking up your hot water heater to a generator. 

But before proceeding, it’s imperative to ensure that the generator and hot water heater are compatible with each other.  

Generator and Hot Water Heater Compatibility

When it comes to hot water heater installation, check if your specific model is designed to be connected to a generator. Some heaters may require additional components or modifications for this setup, so consult the user manual or the manufacturer for guidance.

Power management is vital in hooking your hot water heater to a generator. Knowing the right generator size to run hot water heater is essential. Determine how much power your heater needs and compare it against the output capacity of your generator. It’s essential to have enough power available to run both devices simultaneously without overload or damage.

For example, A typical electric water heater (30, 40, or 50 gallons) needs between 3,500W and 5,500W of power. This information will be on a sign or sticker on the water heater or in the manual.

To power a standard electric water heater, a generator must be at least 500W more powerful than the water heater’s power level. This means that the generator needs to be between 4,000W and 6,000W. 

Emergency preparedness should also be considered when connecting a hot water heater to a generator. Ensure you have all necessary accessories, like appropriate cords and connectors, readily available. 

You’ll need transfer switches and interlock kits to ensure a seamless connection between your power source and electrical system.    

Transfer Switches and Interlock Kits

Transfer switches play a crucial role in managing the flow of electricity between the generator and hot water heater. They act as a safety mechanism that prevents backfeeding, which can damage appliances or even cause fires. By using transfer switches, you can safely switch between utility power and generator power without any interruption. 

Different transfer switch types are available, such as manual transfer switches and automatic transfer switches. Manual transfer switches require you to physically switch between power sources, while automatic transfer switches detect power outages and automatically switch to generator power. 

Interlock kits are another essential component for connecting your hot water heater to a generator. These kits prevent both the main breaker and the generator breaker from being turned on at the same time, ensuring proper isolation of utility power when running on generator power.

When installing transfer switches, avoiding common mistakes such as improper grounding or insufficient wire gauge sizes is essential. It’s also recommended to regularly maintain and troubleshoot your transfer switch to ensure its optimal performance during emergencies. 

Steps on How to Hook Up a Hot Water Heater to a Generator

Now let’s go through the step-by-step process of hooking a hot water heater to a generator. 

Step 1: Install the transfer switch or interlock kit

Proper grounding is crucial to ensure your and your equipment’s safety. Start by turning off the main circuit breaker in your home’s electrical panel and the gas valve if you have a gas-powered heater

Follow the manufacturer’s instructions to install the transfer switch or interlock kit. Typically, this involves mounting the switch or kit near your main electrical panel and connecting it to the generator’s output.

Step 2: Identify and disconnect the hot water heater circuit from the mains

Turn off the power to the hot water heater at the breaker box. This is important to do so that you don’t get shocked when you’re working on the electrical connections.

Locate the circuit breaker that supplies power to your hot water heater in your main electrical panel. This is usually located on the side or back of the hot water heater. Disconnect the hot water heater from the power mains. Two wires will be connected to the hot water heater, one black, and one red. Disconnect these wires by unscrewing the lugs that they’re connected to. 

Step 3: Create a dedicated circuit

Install a new circuit breaker in the transfer switch or electrical panel specifically for the hot water heater. This dedicated circuit ensures that the generator can power the heater independently. 

Step 4: Connect generator wiring

Run electrical cables from the generator to the transfer switch or interlock kit. Connect the generator’s output to the dedicated circuit you created for the hot water heater, usually a 240-volt extension cord. The extension cord should be rated for at least the same wattage as the hot water heater.

Connect the other end of the extension cord to the hot water heater. Ensure that the black wire from the extension cord is connected to the black wire from the hot water heater and the red wire from the extension cord is connected to the red wire from the hot water heater. 

Step 5: Test the setup

With all connections in place, start the generator and turn on the hot water heater. Confirm that the heater is receiving power from the generator. Test the transfer switch or interlock kit to ensure it functions correctly and switches power sources seamlessly. 

For gas heaters, it’s essential to turn off the gas supply and ensure there are no leaks before starting the generator. Electric heaters require an appropriate-sized circuit breaker and wiring to handle the load from both the generator and other appliances.

Safety precautions must be considered when connecting your hot water heater to a generator. Ensure all connections are secure and tight, and never overload your generator beyond its wattage capacity. Follow proper ventilation guidelines for gas heaters and keep flammable materials away from both heaters. 

Potential Hazards

a close-up image of a hot water heater connected to a generator, capturing the precise placement of wires, pipes, and connections

One crucial aspect to be aware of when connecting your generator and water heater is the potential hazards that must be avoided. Making common mistakes can lead to severe accidents, so taking safety precautions and following proper procedures is essential.

  • Understanding the electrical hazards involved in hooking up a hot water heater to a generator is essential. Improper wiring or overloading the system can result in electrical shocks or even fires. To prevent this, make sure you have a clear understanding of the electrical requirements for both your generator and water heater. 
  • A lack of proper grounding can lead to electrocution or damage to your appliances.
  • Without adequate ventilation, carbon monoxide can build up in your home, which can be extremely dangerous. 

It’s crucial to prioritize safety at all times when dealing with electrical appliances. 

Signs of A Malfunctioning Hot Water Heater

One of the most noticeable signs is a lack of hot water or inconsistent temperature. It may be time to investigate further if your showers have become shorter or colder than usual. Another sign to look out for is strange noises from your water heater, such as banging or rumbling sounds. This could indicate sediment buildup or a malfunctioning heating element. 

To troubleshoot common problems with your hot water heater, try adjusting the thermostat settings or checking the pilot light if you have a gas-powered unit. Flushing the tank regularly can also prevent sediment buildup and extend the lifespan of your heater. However, remember that professionals should only handle certain repairs for safety reasons.  

When in Doubt: Contact a Professional Electrician

One of the most common mistakes people make is not understanding the limitations of their generators. It’s essential to check your hot water heater’s wattage and amperage requirements and compare them to what your generator can handle.

The safest option is to use an interlock kit, which allows you to connect your hot water heater to your generator safely. This kit ensures that only one power source can be used at a time, preventing back feeding or electrical hazards.

If you need help connecting your hot water heater to a generator properly, it’s always best to consult a professional electrician. They have the knowledge and expertise to troubleshoot common issues and ensure everything is connected safely and correctly. 

Keep Your Water Hot During a Power Outage! 

To successfully hook up hot water heater to a generator requires careful consideration and adherence to safety measures. Remember the three crucial steps: ensure compatibility between the generator and hot water heater, install transfer switches or interlock kits for seamless power transfer, and follow the provided guidelines diligently. 

Beware of potential dangers such as electrical shocks or improper installation. If you’re uncertain about any aspect of this process, it’s wise to consult a professional electrician who can assist you in achieving a smooth and secure hookup. is an independent review business. I am not affiliated with any manufacturers and do not accept paid reviews. When you buy through my links, I may earn a commission which helps me purchase more generators for testing. - Scott Krager

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