How to Install a Water Pump Relay Switch

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Things You'll Need

  • Two-pole pump relay switch

  • Screwdriver

  • Wire strippers

Water pump relay switches control the operation of the pump's electrical motor. The relay itself is remotely controlled by the water system pressure switch. Typically, the relay is employed when the pump's load amperage exceeds the pressure switch's electrical capacity. Damage can occur to the pressure switch's electrical contacts by excessive amperage. The physical installation of the relay switch should be in a dry location. A high moisture environment can cause a premature failure to the switching mechanism and the electrical contacts.


Step 1

Understand that there will be three pairs of wires connected to the two-pole relay switch. The first pair of wires will be tied to the relay's control coil. The coil produces a magnetic field that operates the relay's electrical contacts. The second pair of wires will be coming from the main panel electrical source or power feed. A 220 VAC pump will use a two-pole circuit breaker or two fuses. The last pair of wires connected to the relay will be going to the pump motor itself.

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Step 2

Mount the two-pole pump relay switch in a dry area, preferably 5 feet off of the floor. Use the vendor provided mounting screws to secure the switch mechanism to a solid wall with the screwdriver.

Step 3

Remove all electrical power from the pump motor circuit. Shut the circuit breaker off or remove all fuses that send power to the pump motor.


Step 4

Use the wire strippers and remove approximately 3/4 inch of the wire insulation to reveal the bare copper wire from all the wires described in Step 1.

Step 5

Attach the wires coming from the pressure switch to each of the screw terminals connected to the relay coil, one wire to each terminal. One of these wires will be a voltage carrying "hot" wire. The other wire will be the electrical system neutral. The voltage between these two wires should be 120 VAC.


Step 6

Identify the following labels on the relay switch. One pair of the screw terminals should be marked "line" and the other pair of terminals will be labeled "load." Connect the wires coming from the main power fuse or circuit breaker to the screw terminals marked "line," one wire to each terminal. Attach the wires going to the pump motor to each of the screw terminals labeled "load," one wire to each terminal.

Step 7

Re-energize the main power by turning on the circuit breaker or reinstalling the power fuses.


Follow all local electrical regulations whenever installing or servicing any type of electrical equipment


Water and electricity does not mix. Keep water from all electrical equipment.


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