How To Hook Up A Furnace To A Generator? Essential Guide

When connecting a furnace to a generator, special codes, and safety precautions must be observed. The generator wattage must be appropriate for the total power needed. Extension cords or suicide cords should not be used, as they may violate building codes. The wattage requirements of appliances must be considered when connecting to a generator. A 5000-watt generator can typically power a gas furnace, water heater, refrigerator, blower, and some lights.  Insurance provided by local electrical suppliers is recommended to prevent facing paychecks due to blackouts and other issues. Make sure to install everything according to NEC guidelines. To keep warm during a power outage, set up your furnace to a generator.

How To Hook Up A Furnace To A Generator

Key Takeaways

  • Don’t forget to get a qualified electrician to help with installation. Additionally, if you’re using an electric furnace instead of gas, you’ll have to upgrade the generator’s capacity to meet higher wattage requirements.
  • Check local building and electrical codes when selecting a generator. Have a licensed electrician install a transfer switch or bypass switch to avoid back-feeding electrical lines that may cause injury or harm.
  • According to NSC, 3% of home electrical fires started due to generators not having a transfer switch.
  • Happy Joe shared a useful video link on the Willthrill81 discussion starter thread that provides a step-by-step solution for installing a transfer switch.

Overview of Hooking Up a Furnace to a Generator

If you want to attach your furnace to a generator, there are certain rules to follow. To keep things secure and up to code, you’ll need a transfer switch. Here are the steps to take:

  1. Calculate the total wattage for all the appliances you’ll need in a power cut, e.g. furnace, refrigerator, water heater, and blower.
  2. Buy a generator that can handle this wattage. Different power capacities are available.
  3. Place a transfer switch between the main breaker panel and the generator inlet. This keeps electricity from flowing back and creates a safe connection to your home wiring.
  4. Connect the transfer switch to your furnace’s circuit breaker with wiring or extension cords. Stick to NEC codes for electrical installations.

Don’t forget to get a qualified electrician to help with installation. Additionally, if you’re using an electric furnace instead of gas, you’ll have to upgrade the generator’s capacity to meet higher wattage requirements. 

Label each outlet and appliance connected to the transfer switch, it makes it easier to identify them when in use. And make sure your furnace wattage needs are covered!

Understanding the Wattage Requirements for Your Furnace

It’s key to understand your furnace’s wattage needs when powering it. This helps you pick the right generator and switch, and comply with building codes. Here’s a quick look at typical wattage for furnaces:

Furnace TypeWattage
Gas Furnace (Blower Only)500-800 watts
Natural Gas Furnace (with Ignition)400-600 watts
Electric Furnace (10kw)7,000-10,000 watts

These are usually the right wattages, but yours may vary based on model and blower size. Additionally, electrical codes must be followed when using a generator or any other backup power source. Have a qualified electrician install a transfer switch or bypass switch to prevent back-feeding electricity from generators, and ensure safety if someone enters your home.

Prepare for winter power outages now. Don’t wait until it’s too late! Investing in the necessary set-up will keep everyone comfortable and safe. Make sure your generator has enough wattage to power your furnace.

Choosing the Correct Generator for Your Furnace

To provide your furnace power during a black-out, pick the suitable generator. Select the generator with plenty of power output according to the size and wattage your furnace needs.

Here’s a table with the suggested wattage for different furnaces:

Furnace TypeRecommended Wattage
Gas Furnace800-1,200 watts
Oil Furnace1,000-1,500 watts
Electric5,000-7,500 watts

Remember, some devices such as water heaters and blowers may require extra wattage. Consult a certified electrician to find out if you need more wattage than suggested.

Check local building and electrical codes when selecting a generator. Have a licensed electrician install a transfer switch or bypass switch to avoid back-feeding electrical lines that may cause injury or harm.

Connecting a generator to your furnace without a transfer switch is like taking a bath with an electrical appliance – stay away from it!

Using a Transfer Switch to Safely Connect Your Generator to Your Furnace

Connecting a generator to your furnace can be a risky task, and hence, using a transfer switch is the most appropriate way to do it safely and efficiently. 

A transfer switch is a manual device that directs and switches electrical loads between power sources.  It not only prevents backfeed but also ensures that only the needed appliances are operating, without the risk of exceeding the total power that the generator can produce.

Here’s a simple 3-step guide for using a transfer switch to safely connect your generator to your furnace:

  1. Install a transfer switch by a qualified electrician: It’s essential to have a transfer switch installed by a professional who will make sure to comply with the electrical code and wiring standards to ensure safety.
  2. Connect your generator to the inlet box: The inlet box is wired and mounted outside your house, and it makes it easy to plug in any generator to power your home. Connect the generator cord to its plug, and then plug it into the inlet box.
  3. Connect the transfer switch to your electrical panel: Once the power from the generator is flowing through the inlet box to the transfer switch, have it connected to your house wiring panel to power up your furnace and other essential appliances.

If you’re unsure of what size transfer switch you need for your furnace, it’s best to consult an electrician. It’s essential to adhere to the building codes and electrical codes to ensure safety and avoid any insurance issues that could arise.

Don’t put yourself and your home at risk. Get your transfer switch installed today! Installing a transfer switch: Because waiting for the power to come back on after a storm is about as fun as watching paint dry.

How to install a Transfer Switch?

To make sure your generator and furnace have a safe connection, you need to install a transfer switch. Follow these five steps for a smooth installation:

  1. Pick the right switch: Look at your power needs and choose the switch that fits your furnace’s electrical circuit.
  2. Turn off the power: Cut the main circuit breaker and stop the power supply to your furnace.
  3. Mounting: Keep the transfer switch close to your furnace, but away from children and pets.
  4. Connect wires: Connect the transfer switch to the home’s electric panel, following the manual’s instructions.
  5. Test the connection: After everything is connected, turn on the power supply and check if it works.

Professional help is recommended if you’re not confident in installing a transfer switch. Test your transfer switch connection regularly to make sure it’s ready for emergencies. Without it, your generator and furnace can be electrically dangerous.

Importance of a Transfer Switch for Safety

Smartly operating your generator needs understanding the need for a transfer switch. It improves safety by giving a secure connection, avoiding back-feeding into power lines that could cause electric shock or fire.

  1. With a transfer switch, safely use your backup generator, running vital appliances without risking damage in an emergency. 
  2. It maintains the security of your power sources in potential emergencies and routine usage. It preserves the well-being of family and household circuits.
  3. Transfer switches can be integrated into different generators, from small portable models to larger standby systems. 
  4. An expert electrician provides an extensive evaluation to identify which option meets the most efficient standard.
  5. Homeowner satisfaction rises with a transfer switch, after experiencing power outages with non-functional backups. 
  6. According to NSC, 3% of home electrical fires started due to generators not having a transfer switch.

It’s not rocket science – it’s electrical engineering.

Wiring Your Generator to Your Furnace

As a qualified electrician, connecting your generator to your furnace is essential during a power outage. Here’s the best way to wire your generator to your furnace without risking your safety and violating building codes:

  1. Purchase a transfer switch that isolates your furnace circuit from your main panel and connects it to the generator. Ensure that the transfer switch is compatible with the wattage of your generator and furnace.
  2. Hire a professional electrician to install the transfer switch and wiring, as wiring mistakes can cause electrical fires and damage appliances. Alternatively, you can install the transfer switch yourself if you are confident with your electrical skills.
  3. Connect the transfer switch to your generator through a dedicated cord that plugs into the inlet on the transfer switch. Do not use a standard extension cord or “suicide cord” as it can overload the circuit, damage appliances, and cause electric shock.
  4. Test your generator and transfer switch system to ensure that it works correctly and can power your furnace and other essential appliances.

Remember, the size of your generator and the total power you require depends on the items you need to run, such as your furnace blower, water heater, refrigerator, and other appliances. It is also essential to follow electricity codes to avoid back-feeding and injuring someone.

According to the National Electric Code (NEC), you should install a transfer switch and bypass switch to connect your furnace to the generator properly. 

Happy Joe shared a useful video link on the Willthrill81 discussion starter thread that provides a step-by-step solution for installing a transfer switch. When it comes to hooking up your furnace to a generator, using a power cord and plug is like trying to fix a heart attack with a Band-Aid.

Use a power cord and plug to connect the generator to the transfer switch

Secure your furnace during power outages by connecting a generator to it using a power cord and plug. Here’s what you need to do:

  • Pick a power cord of appropriate rating for your generator.
  • Attach one end of the cord to the generator’s output receptacle.
  • Cover the plugged end with a weatherproof cover.
  • Plug the cord into an inlet receptacle connected to a transfer switch.
  • Connect wiring from the switch to the furnace.

This method is convenient and cost-effective. Plus, you can move your generator further away from your home or connect multiple outlets.

Be sure to take safety precautions like using outdoor-rated extension cords, avoiding overloads, and switching off electronics before switching over to generator power. Take the necessary steps now and guarantee continuous power.

Use an extension cord to connect the generator to the transfer switch

If you want to connect your generator to a transfer switch, consider these steps.

  • Check that the extension cord is the right length and can handle the load of the generator.
  • Both ends should have two male plugs that fit standard 4-prong outlets.
  • Connect one end to the generator and the other end to an inlet on an exterior wall with a grounding rod.
  • Run wires from the inlet box into your home, to the transfer switch.
  • Plug in and turn on both the generator and switch.

For safety, always double-check outlets and unplug them when not in use. Be prepared – run your furnace on a generator and enjoy some cozy hot cocoa or whiskey!

Running Your Furnace on a Portable Generator

If you’re looking to run your furnace on a portable generator, it’s best to use a transfer switch. This switch allows you to safely power your furnace and other appliances without back-feeding into the grid. 

You’ll need to use proper cords and plugs and ensure the generator is the right size for your furnace’s wattage. It’s essential to follow building and electrical codes and have the installation done by a qualified electrician. Running a furnace on a generator can be a safe and effective solution during power outages, but it depends on the setup and safety measures taken.

A fact is that back-feeding power into the grid can be dangerous and even illegal in some areas. 

According to Happy Joe, a user on a DIY forum, he had a close call with a generator when he accidentally back-fed power into the grid. It caused a surge that damaged his appliances and almost caused a fire.

Understanding the Limitations of Using a Portable Generator

Before using a portable generator to power your furnace, it’s essential to understand its limits. The generator won’t necessarily generate the same amount of energy that your furnace needs. So, you need to check your furnace’s wattage and the generator’s capacity.

Using a generator for a long time can reduce its life or damage your furnace’s parts if not connected properly. Be sure to follow safety instructions, such as giving enough ventilation and keeping it away from combustible materials.

It’s also important to maintain both the generator and the device it powers. If you neglect this, you could face damage or downtime due to equipment malfunction.

To make sure this doesn’t happen, consult an electrician before connecting them. This can help you make better decisions and ensure safe operation in the long run. Remember: your generator isn’t a magic wand – stick to the basics and avoid potential danger.

What other appliances or furnaces can run on the same generator?

Wondering which devices can run on the same generator as your furnace? We have a table for you! Check out the average watts used for various appliances and furnaces:

Appliance/FurnaceAverage Watts Used
Refrigerator600 watts
Microwave Oven (1000-watt)1500 watts
Coffee Maker (4 cups)600 watts
Space Heater (1500-watt)1500 watts

Electrical codes and regulations – scary, right? But, it’s much better to be safe than sorry when hooking up your generator. Don’t want to start any electrical fires!

Electrical Codes and Regulations for Hooking Up a Generator

When hooking up a generator to your electrical system, it is important to adhere to the electrical codes and regulations. One of the most crucial aspects of hooking up a generator is the installation of a transfer switch, which allows you to switch between using grid power and generator power.

To ensure that your installation is up to code, it is essential to have a qualified electrician handle the job to guide you in selecting the right size of the generator, transfer switch, and power inverters for your home. Moreover, a certified electrician will make sure to follow the National Electrical Code (NEC).

Another critical factor to keep in mind is using safety devices like a suicide cord or an inlet box when hooking up your generator. While some people use extension cords to connect the generator directly to the appliances, this is not safe as it can cause back-feeding.

In 2011, a Californian man backed grid power through his generator, causing electricity to flow back out of his home and through the street. This caused a potentially deadly situation for workers attempting to repair the grid. It is vital to use safety devices and follow codes and regulations to avoid such incidents.

Staying up-to-date with NEC standards as safety isn’t a joke unless you’re an electrician with a dark sense of humor.

Keeping up to date with National Electrical Code (NEC) standards

It’s important to keep abreast of National Electrical Code (NEC) standards when hooking up a generator. This makes sure installations are compliant with federal and state regulations and prevents safety hazards. Staying up-to-date on these guidelines is important to ensure system functionality and lower risks.

Review NEC every three years because changes and amendments are made during each revision cycle. These might include new requirements, better technical info, addressing gaps in previous editions, new tech and advancements, and user suggestions.

To comply with NEC rules for generator wiring is a must. Otherwise, insurance policies can be voided without proof of conformity.

Follow all electrical codes and get permits from relevant authorities before you design or install a generator. It’s better to pay for a qualified electrician than suffer from a DIY job – both financially and literally.

Hiring a qualified electrician to ensure proper installation and safety

Hiring a skilled electrician for generator installation is essential. They are trained and have the necessary tools. They also know electrical codes and regulations. It’s important to hire a licensed and certified electrician with lots of experience. This ensures effective communication and a better understanding of safety risks.

Don’t hire anyone who is not qualified. It could lead to malfunctioning equipment or even electrical fires! Therefore, professional expertise should be the priority when choosing an electrician.


It’s key to keep in mind that any generator connected to your furnace must follow electrical codes in your region. Hire an electrician or find out what local authorities say before proceeding. Remember to check the wattage for both the generator and furnace. A transfer or bypass switch installed by an expert may be necessary. Do not use a suicide cord, as it can lead to back-feeding, which can be deadly. Inspect cords and extension cords thoroughly; check they are in good condition and suitable for the total power output. Label all cords, wires, and boxes for easy identification of each appliance’s connection. You may need a generator with higher wattage if powering more than one appliance. Natural gas furnaces require less wattage than oil furnaces.