How to Wire Irrigation Pump Relays

The process of wiring a pump to an irrigation system is a confusing process. It requires a certain amount of concentration and in many cases has to be done by a certified professional. Many localities require inspections when a home irrigation system is installed, especially when the system is run off a well or water captured from a ground level source. The process is confusing, but a homeowner can complete it with a basic knowledge of electrical wiring.

Step 1

Make sure the power is turned off to the pump power supply. Place a piece of electrical tape over the breaker to ensure the breaker remains off.

Step 2

Determine the location for the pump relay. Many manufacturers recommend mounting the relay no less than 15 feet and no more than 20 feet from the irrigation controller. Once the proper location is determined, mount the relay according to manufacturer's instructions.

Step 3

Run two irrigation wires from the controller to the relay box, one white and one red. Connect the red wire to the "MV Pump" Terminal on the irrigation controller and the white wire to the "COMMON" terminal on the controller. Refer to the owner's manual for the correct location of these terminals.

Step 4

Connect the red irrigation wire to the "24 +" terminal and the white wire to the "24 Com" terminal inside the relay box. These wires tell the relay to turn the pump on and off.

Step 5

Run the power wire from the breaker panel to the inside of the relay box. This should be done by a certified electrician. Strip the ends of all the wires to reveal a half inch of bare copper wire.

Step 6

Connect the "L1" wire from the breaker panel to the "L1 Input" terminal inside the relay box. Some relay boxes will require wire nuts to connect the wires and some will have screw down terminals for the wires.

Step 7

Connect the "L2" and "Ground" wires from the breaker panel to the "L2 Input" and "Ground" terminals inside the relay box.

Step 8

Run the wire from the pump to the relay box. Have the connection on the pump completed by a licensed electrician or plumber. This will ensure the connections are made properly.

Step 9

Connect the "L1", "L2" and "Ground" wires from the pump to the "L1 Output", "L2 Output" and "Ground" terminals inside the relay box.

Step 10

Double check the connections. Fold the wires inside the relay box and close the cover.

Step 11

Turn the power on to the pump at the breaker panel. Turn the irrigation system on and check to make sure the pump comes on. If the pump does not come on with the system, then turn the power off to the pump and re-check all of the wiring.

About the Author

Michael Rippetoe has been writing for 15 years, and has recently decided to make it his career. He has been a journeyman carpenter, ASE Master Mechanic, certified irrigation professional and currently writes for this site, designs websites, and does professional photography. Rippetoe's articles appear on eHow, Garden Guides, AnswerBag and others.