How to Install a Generator for a Sump Pump

Install a generator to keep your sump pump working during power failures.

Determine the horsepower of your sump pump (probably 1/2 or 1/3).

Calculate the wattage requirement to start the pump. A 1/2 hp pump requires 2,150 watts to start and a 1/3 hp pump requires 1,300 watts. The wattage requirement to operate the pump after start-up is approximately 60 percent of the total.

Consider whether you want your generator to run other appliances during a power failure. Calculate the wattage requirements to run these appliances as well. A typical refrigerator requires about 2,200 watts to start and about 700 to run thereafter. Lights require the wattage of the bulb.

Purchase a generator of sufficient wattage for your needs.

Have a qualified electrician install a transfer switch if you intend to use the generator for backup power to the house. This is not necessary if you intend to simply plug the pump and any other appliances into the generator manually as needed.

Keep sufficient fuel on hand to operate the generator.

Follow all operating and safety instructions that come with the generator.

Things You Will Need

  • Generators
  • Sump Pumps


  • You do not need a generator sufficient to start everything simultaneously. You can manually hook up the refrigerator and lights after the pump has started.


  • Generators have a maximum and a rated output. The maximum output should never be sustained for more than 30 minutes, so you can figure on the maximum for starting appliances, but not for sustained operation.

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