Installing a Switch for a 240 Volt Pump

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Methods of Wiring a Switch for a Pump: How to Wire a Control Switch for a 240 Volt Pump.

Why a Double Pole Switch is the Best Choice

Electrical Question: I have a 2 hp, 240Volt Irrigation Pump to supply lake water to a hose.

  • The pump has a maximum current draw of 15.4A (listed on the label).
  • The pump is on a dedicated 240V, 20A circuit.
  • I would like to add a switch to be able to turn the pump on and off.
  • Can I use a 240V, 20A single pole switch for the black wire or do I need a double pole?

This electrical question came from: Philip, a Homeowner from Mooresville, North Carolina.

Additional Comments: Great site.

Dave’s Reply:
Thanks for your electrical question Philip.

Wiring a Switch for a 240V Pump

Application: Irrigation Pump Switch.
Skill Level: Intermediate – Best performed by a Licensed Electrician.
Tools Required: Basic Electricians Pouch Hand Tools and Voltage Tester.
Estimated Time: Depends on personal level experience and ability to work with tools and electrical wiring.
Precaution: Identify the pump power 240v circuit at the electric panel, turn it OFF and Tag it with a Note before working with the switch wiring.
Materials: Make sure the switch is rated for the electrical circuit, which in this case is 240volts 20 amps.

How to Wire a Control Switch for a 240 Volt Pump

  • Wiring a Control Switch for a 240 Volt Pump
    • When controlling a 240 volt motor, it is best to install a double pole switch for this irrigation pump.
    • A double pole switch is the safest way to make sure that both lines of the 240 volt circuit power to the pump are turned off.
    • A double pole switch has four termination points, two for the 240 volt Line of the electrical circuit, and two for the Load which leads to the pump motor.
  • Alternative On-Off Control for a 240 Volt Pump
    • A relay contactor may also be used to control a pump motor.
    • A low voltage control circuit would be required which could be wired into the 240 volt pump circuit wiring, and the control circuit will need to have over current protection.
    • The control circuit wiring could then be wired to a single switch located at a remote location.
    • The low voltage wiring would be connected to a 240 volt relay contactor which would have a low voltage coil which matches to control voltage that is used.
    • Typical low volt control circuits are 24 volts ac, therefore low volt control wiring may be used, however the gauge of the control circuit wire must be sized according to the length of the control circuit.
  • Disconnect Switch at the Pump
    • A 240 volt disconnect switch should also be installed at the location of the pump motor to ensure the circuit power is turned off before servicing the pump motor or associated components.

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FAQs Frequently Asked Questions and Comments

3 Responses to “Installing a Switch for a 240 Volt Pump”
  1. Dave Rongey says:

    Hi Angelina,
    Please understand that the exact wiring will depend on the specific application and equipment, however let me see if I can help you understand what may be happening.
    Because you mention that a relay is involved, then this would indicate that there is a control circuit which is most likely a lower voltage than that of the pump. Control circuits are commonly used when there are one or more sensors or devices that would determine if the pump should be on or off.
    If you want to simply be able to turn the pump on or off then you should understand that you will be over-riding other devices or critical equipment and this could cause a problem. For example a pump must be on or water flow must be occurring if a heating element is turned on otherwise there may be damage due to an overheating condition. Situations such as this are best determined by a qualified pool equipment technician or representative of the pool equipment that you have. If it is determined that a switch may be installed then it may be much easier to install a switch within the control circuit of the pump, but the location within the control circuit must be carefully understood to prevent problems. A qualified service technician will also make sure that any electrical wiring will conform to the required GFCI Protection of the pool equipment.
    I hope this helps.

  2. SharingKnowledge says:

    How do you wire an on/ off switch to a pool pump relay?
    It is a furnace 240 20 amp.
    Also the switch currently will not turn off the relay but the relay turns off and on , and works with the breaker turned on/off.
    Thank you so much!

  3. Asondo Philip Mimba says:

    Can someone design to me how a 3phase automatic generator is connected to a switch board and the main supply?


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