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How to Wire a Three-Wire Well Pump

A three-wire well pump actually uses four wires---a start, run, common and ground wire---plus a control box. The control box, which usually mounts to a wall near the well's storage tank, feeds power to the pump's motor through the start wire until the motor reaches operating speed. The control box then switches the pump motor's power feed to the run wire. The control box's start capacitor supplies the extra power during start-up.

Wire a Three-Wire Well Pump

Turn off the circuit breaker on the well pump's control box. The correct circuit breaker often uses a "Well" label. In many cases, the well pump's circuit breaker mounts to the "Main" circuit breaker panel, located outside, next to the electric meter. Verify there is no power present by touching the wires with a Non-contact voltage tester.

Strip 1/2 inch of insulation from the four color-coded wire strands in the cable that leads to the well. The cable exits the bottom of the control box and travels to the well.

Slip a heat-shrink wire connector's shrink tube over the end of each color-coded wire strand in the cable from the control box. Heat-shrink wire connectors use crimp-on metal connectors and a water-tight plastic sleeve.

Push one end of the heat-shrink metal wire connector onto the end of a wire strand in the cable that leads to the control box. Crimp the metal wire connector onto the wire, with a crimping tool. Repeat for each wire strand.

Push the three-wire well pump's green wire into the wire connector on the cable's green wire. Crimp the wire connector onto the well pump's green wire with the crimping tool. The green wire grounds the well pump.

Push the three-wire well pump's yellow wire into the wire connector on the cable's yellow wire. Crimp the wire connector onto the well pump's yellow wire with the crimping tool. The yellow wire connects to the neutral or white wire.

Push the three-wire well pump's red wire into the wire connector on the cable's red wire. Crimp the wire connector onto the well pump's red wire with the crimping tool. The red wire sends voltage during start-up.

Push the three-wire well pump's black wire into the wire connector on the cable's black wire. Crimp the wire connector onto the well pump's black wire with the crimping tool. The black wire sends voltage to the pump after start-up.

Slide the heat-shrink wire connector's plastic sleeves over their respective metal wire connectors. Center the plastic sleeve over the wire connector.

Heat a plastic sleeve with a propane torch. Start at the center and work to each end. The sleeve shrinks and sealant oozes out of the ends of the sleeve once its temperature reaches the correct level. Repeat for each plastic sleeve.

Things You Will Need

  • Heat-shrink wire connectors
  • Crimping tool
  • Propane torch
  • Non-contact voltage tester

Tips

  • Call a professional (found under the "Water Well Drilling and Servicing" section of the local phone book or online) if questions or safety issues arise.
  • Try and use a shrink tube torch with a bushy flame when heating the shrink tube. Keep the flame approximately 10-12 inches away from the heat shrink.

Warnings

  • Never attempt to work on a well pump without first turning off the circuit breaker.
  • Always aim the torch's flame in a safe direction. Never point the flame toward anything flammable.
  • Avoid touching the torch's flame.

About the Author

Based out of Central Florida, Robert Sylvus has been writing how-to and outdoor sports articles for various online publications since 2008. Sylvus has been a home improvement contractor since 1992. He is a certified HVAC universal technician.

Photo Credits

  • Jupiterimages/Polka Dot/Getty Images