Pump Relays

Pump relays are installed between an irrigation controller and a non-automatic pump so that the controller – which only sends out 24 volt DC signals – can instruct the pump to start or stop when an irrigation zone opens or closes. A relay is used because the controller does not itself have the electrical handling capacity to switch the up to 2 kilowatts of AC power that some pumps use. Therefore it uses a ‘middleman’ to do it – a relay.

A relay is therefore effectively an electrically powered on-off switch for mains power, and is triggered by a 24v signal from the controller to let mains power go to the pump.

There are 2 main types of relays – mini-relays, which are good for pumps up to 750 watts, and contactors, which are good for up to 2 kilowatts.

Both types can sit in a small electrical box and are wired in a similar way.