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How Many Watts Should I Get for a Generator?


Where generators are concerned, wattage is so often synonymous with size. Small models can power one or two appliances, and large home-standby generators tend to have enough in the tank for powering an entire home. According to GeneratorWhiz, it’s essential to consider your specific purpose for a generator to know what size to purchase.

However, before we get to your options, let’s first widen your understanding of generator wattage. This should offer a good start for choosing the best generator for your family.

Understanding Generator Wattage

Wattage is the power the generator needs to make to keep your chosen devices and appliances running during an outage. It is categorized into the following:

Starting Wattage

From its name, it’s the wattage needed by appliances to power on. Typically, this number is around two to three times more than an appliance requires to keep running. Most appliances need more juice to start up and not as much to keep operating.

When the power goes off, the generator should handle the surge from appliances that continue running: the freezer, heater, refrigerator, and more. If your washing machine happens to be running at the time, the machine would have to possess enough power to keep it running, too.

Running Wattage

Otherwise called rated wattage, running wattage is what a device or appliance needs to run throughout an outage. More often than not, this figure is enough to let you know how much power is needed to run what needs to be kept running. If not, you may have to consult the surge wattage to determine the generator size.

Surge Wattage

The peak wattage amount a generator is capable of producing. If you’re looking to run everything off the generator, you should choose a machine with around 1,000 to 2,000 additional watts to accommodate the surging.

Appliances To Keep Running

Generator size is determined mainly by the number of devices you want to continue operating during an outage. List down these appliances and their respective wattage requirements. Then, add up the amounts to calculate the total wattage. When choosing a generator for a home or a worksite, work with the figure you obtained.

A specific appliance’s wattage requirements are usually found on the user’s manual. Sometimes, your specific machine is even labeled with them. That said, you may still need to use a generator calculator or enlist the help of an experienced electrician to get an accurate wattage estimate. The figure must never be more than your chosen generator’s wattage output.

If you’re worried about overloading your machine, keep it from powering more than two appliances at a time. Also, avoid using them to power devices with high-wattage requirements. Since we’re dealing with emergency power equipment, don’t forget to overlook devices you may need to power during a storm or a minor flood.

To give you an idea of the generator size to go for, here are the approximate running watts of some common household appliances:

  • Toaster: 1,500 watts
  • Coffee Maker: 500 watts
  • Microwave: 1,200 watts
  • Freezer: 800 watts
  • Television: 300 watts
  • Electric Oven: 5,000 watts
  • Computer: 1,500 watts
  • Hairdryer: 1,200 watts
  • Cell Phone Charger: 10 watts
  • Washing Machine: 750 watts

Heating and cooling systems approximate wattage requirements:

  • Electric Furnace: Up to 20,000 watts
  • Central AC: Up to 4,000 watts
  • Sump Pump: 1,500 watts
  • Outdoor Lighting: Up to 1,000 watts
  • Water Heater: Up to 4,500 watts

Note that these merely approximate and could vary depending on your specific appliance’s model. Thus, the safer course of action would be to reference the owner’s manual. Add the amounts that correspond to each appliance’s highest possible wattage usage, then add another 100 or 200 watts on top of the total to be sure.

Backup Needs Should Require No More Than 90 Percent of the Generator’s Power

You don’t want your generator operating at full capacity every time there’s an outage. Aside from how this could wear the machine down prematurely, it could easily cause an accidental overload.

As a safety rule, experts recommend choosing a generator that doesn’t need to operate more than 90 percent to keep necessary appliances running. Doing so prevents the unit from overworking to produce the energy your home needs.

If your location tends to experience prolonged power outages, a home standby generator or large inverter should do the trick more often than not. 

Use Your Generator Safely

Once you’ve chosen a generator fitting your power needs, make sure it runs at least 20 feet away from your home for maximum safety. The direct exhaust should face away from doors and other entryways and the HVAC unit. You should also understand how its specific system works before hooking it up.

The ideal selection process should involve browsing reviews online, particularly those that provide firsthand experience on specific generators and their safety levels.

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