How Much Generator Power Do I Need?

If you’ve decided to get a backup generator to keep your home operating when the power goes out, you may now be overwhelmed by all the choices of power available. The top brand, Generac, makes generators ranging from 7.5 kilowatts to 150 kilowatts. How much power will your house need if the power goes out for a while? Let’s find out. 

Here are a few appliances that are crucial for most people, along with an estimate of how much wattage they need to start up. The second number is the wattage they need to run. (Only appliances with motors need extra power to start up. Many electrical devices such as TVs, lights, space heaters and coffee makers do not.)

Refrigerator/freezer – 2200 / 700 watts

Window AC Unit – 1800 / 1200 watts

Sump Pump (½ HP) – 2200 / 1050 watts

Furnace fan (½ HP) – 2350 / 800 watts

Television – 500 / 500 watts 

According to Home Depot, you should get a generator that can handle all the running wattages combined, plus the highest starting wattage. For the above assortment, that adds up to 6600 watts, so you would want at the very least a 6.6 kilowatts (kW) capacity unit. 

Another handy way to calculate the power level you need is to use the Home Backup Generator Sizing Calculator from Generac. You just add your zip code along with the rough square footage of your home, and then select how much of your home you want to back up (the entire house or just a few essential appliances) and let Generac do the rest. The calculator assumes by default that you have natural gas for your heater, stove and water heater, but if your home is all electric there is an option to add those electric appliances to the equation as they will need power. 

If the generator these estimates suggest for you are a bit beyond your budget, there are sacrifices you can make to get by with a smaller unit, besides the aforementioned method of powering select appliances instead of the whole house. You can also start your major appliances (AC, sump pump, heater, refrigerator) separately. To stretch your power even further, you could opt to not run some of these appliances at the same time. Whatever you choose, make sure to not burn out your generator by running it beyond its capacity. This can damage it or even cause a fire. For sake of safety, avoid running your generator above 90% of its capacity. 

Also, make sure your home backup generator is professionally installed. This ensures you make the most efficient use of your home generator, and that all safety regulations are followed carefully. Since this device is attached to your home, you can never be too safe.  Seidel Electric Inc helps home and business owners throughout the Blairstown, New Jersey area with advanced electrical solutions. Whether you need generator repair or want to install a new unit, our qualified technicians will arrive to offer friendly and professional support. Contact our team today to learn more about our services and financing options.