Electric Well Pump Circuits

By Dave Rongey - Summary:

Can I power my shed with 120volt from the 240volt well circuit? Installing a 240volt 3wire Circuit for a Well Pump Panel, Dedicated Circuit for Well Pumps.

240 Volt Well Pump Circuit

Electrical Question: Can I power my shed with 120volt from the 240volt well circuit?
I have an existing 240 volt electrical service to a well pump.

  • I have an existing 240 volt electrical service to a well pump.
  • I’m building a shed next to the well.
  • Can I connect to one hot wire and the neutral to extend 120 volt power to the shed from the pump junction box?

Thank you.

This electrical wiring question came from: Allen, a Homeowner from Waynesboro, Pennsylvanian.

Additional Comments: Great site especially with the ability to ask a question and receive an answer.

Dave’s Reply:
Thanks for your electric wiring question Allen.

Application: Installing a 240 Volt Well Pump Circuit and Powering a Shed.
Skill Level: Intermediate to Advanced, Best installed by a Licensed Electrician or Electrical Contractor.
Tools Required: Basic Electricians Pouch Hand Tool, Voltage Tester, trenching equipment or shovels .
Estimated Time: Depends on personal level experience and ability to work with tools and the condition of the soil where electrical conduit will be installed.
Precaution: Identify the pump circuit or power source, turn it OFF and Tag it with a Note before working with the wiring and connections. Working in an electric panel is dangerous due to arc flash hazards and the possibility of electric shock.
Notice: Installing pump circuit wiring should be done according to local and national electrical codes with a permit and be inspected.

The Limitations of a Dedicated 240 Volt Well Pump Circuit

  • Well Pump Circuit Requirements
    • The 240 volt pump circuit to your well pump does not have a neutral, so you cannot get 120 volts without doing something that would be unsafe.
  • Dedicated Circuit for Well Pumps
    • The circuit to the well pump is a dedicated circuit designed for the load of the well pump only.
  • 120 Volt Power for a Pump House Light and Heat Cable
    • Shed It is best to install a new circuit to your shed and leave the well pump circuit as it is.
    • This is a common over sight when power is being installed to a well or pump house.
  • Pump House Electrical Panel
    • My recommendation is to install a sub panel, especially if there is a shed or pump house which will provide the capability for additional 120 volt circuits for lighting and an outlet for freeze tape or other heating devices to prevent frozen water pipes.
    • In most cases such as yours you are limited to the pump circuit and that is all. As described, for some applications this serves just fine but there is an alternative way to serve the well pump and electrical power to a shed or pump house as described next.
  • Installing a 240volt 3wire Circuit for a Well Pump Panel

    • It may be a better idea to install a larger conduit and pull in a larger 240 volt 3-wire circuit and ground to feed a sub-panel.
    • Then provide the 240 circuit for the well pump from the panel, and at least one 120 volt circuit for lighting and a GFI utility outlet.
    • It is always best to plan your electrical circuits and consider all of the potential devices that may be used or added so the circuit may be properly sized and configured.

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FAQs Frequently Asked Questions and Comments

6 Responses to “Electric Well Pump Circuits”
  1. Dave Rongey says:

    Hi Jess,
    If I am not mistaken, there is a check valve between the well pump and the pressure tank to prevent back flow to the well, and there should be a check valve on the top of the pump as well. The operation of the pump to maintain the pressure of the system will depend on the position of the check valves and the pressure switch. So I’m thinking that if the check valve for the system above ground is positioned before both tanks then just one pressure switch will be controlling the pressure of the whole system, therefore a second pressure switch may not be required. Besides, both tanks will be supplied from one common line, so the operation is still limited to the single well pump, you are just branching off of the system. It would be good to make sure to have an isolation valve for each service before the tanks.
    These are just my own thoughts, you may want to share your project with your local well pump expert and get their feedback. Keep in mind that my thoughts reflect a typical set up where the pressure switch is located at the well head, and the water system branches out from that point to the home services.
    I hope this helps,

  2. Jesse Allen says:

    I have a home supplied with a submersible well pump motor. The pressure switch and control box is installed in a closet in my garage. I am moving a Mobil home in the back for my mother. I have a existing water line straight off my well head going to a frost free water hydrant. I would like to use this line for her water supply with a separate tank and pressure switch in a small building close together. My question is how do I wire both services where the will not interfere with each other when they both are calling for water. Thanks Jess

  3. Dave Rongey says:

    Hi Ron,
    The wiring connection to the control box will depend on the type of control box you have. Typically a control is nothing more than a switch where there are one or two pairs of contacts that are used for turning the pump on and off. This is referred to as the LINE and LOAD. The LINE is the power source and the LOAD is the equipment that is being controlled, in this case a pump. If the control is manual then a neutral wire may not be required.
    I hope this helps,

  4. ron says:

    I have a 3 wire 110 volt submersible pump I want use just for irrigation. I have 115volt control box for a 3 wire 110volt pump. I know where to hook the red yellow and black wire from the pump, but where do I hook the neutral and hot wire from my 110 to the L1 and L2 leads on the control box?
    Thank You.

  5. Dave Rongey says:

    Hi John,
    Please excuse the simplicity of this answer, but what does the instruction sheet tell you that came with the pump? All well pumps come with a wiring diagram which provide specific instructions for your specific pump. In most cases if the leads are the same color then the polarity does not matter, but check this with the installation sheet and wiring diagram. Wiring a pressure switch is simply breaking the circuit power through the pressure switch contacts.

  6. John Schulze says:

    Trying to hook up my 110V well pump. The pumps pigtail has 2 identical black wires and a black and green wire. The black and green is the ground? Does it matter which black wire is connected to the white wire and the black wire on my 10 2 with a ground. Need help wiring the pressure switch too please. Thanks John.


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