Can a Portable Generator Run a Submersible Well Pump?

Unfortunately, longer term power outages seem to be happening more frequently each year, and if you have a submersible well pump, no power means no water!

You may have a portable generator that looks like it should be able to run your pump without issue. You hook the generator to your transfer switch and fire it up, but no water flows into your home! What could be going on?

Generator Types: 

There are two types of generators. You need to know which type of generator you have. Consult your generator’s owner’s manual.

  1. Internally Regulated
  2. Externally Regulated

Pump Types: 

2-Wire Submersible Pump: 

  • Starting capacitor is located inside the pump 
  • H2O exclusively recommends and installs 2-Wire, Franklin Submersible Pumps

3-Wire Submersible Pump:

  • Starting capacitor is located outside the pump
  • Will have a small box mounted on the wall near your pressure tank

Depending on what type of generator you have will impact its ability to run your well pump. 

Most of the pump sizes we install are between ½ hp and 1 hp. Below is a general chart from Franklin Electric with recommended requirements on generator size to submersible pump size. 

Please Note: This chart is for 3-Wire, Submersible Franklin Pumps! If you have a 2-Wire pump, you need to increase the minimum generator operation rating by 50%!

well pump information

Starting Amps vs. Running Amps: 

In H2O's experience, the biggest issue with a generator not running a well pump is because of it's high Starting Amps.

Starting Amps:

  • Amperage required to start the pump 
  • Usually only last a fraction of a second or so
  • Can be significantly higher than Running Amps

If your generator is not capable of providing the power necessary to reach these starting amps, your well pump will not be able to run.

Running Amps: 

  • Amperage required to run the motor once started

Franklin Electric has produced a short video answering some questions on generator sizing for pumps and possible issues. You can find it here.

As every generator is different we advise customers to reach out to their generator’s manufacturer if they have any questions regarding its ability to power your well pump. 

To see Franklin Electric's AIM instruction manual for your submersible well pump, please see this link.

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