Relay Boxes

Relay Boxes are an essential item when using Irrigation Controllers, Fertigation Controllers or Greenhouse Environment Controllers.

The Relay Boxes use low voltage signal currents to switch 230/240Volt appliances on and off when required.

Some examples of this would be:

  • Turning a main irrigation pump on and off
  • Turning extraction fans on and off
  • Turning greenhouse/growroom lighting on and off.
  • Turning heaters or chillers on and off.

All a grower needs to do is plug their mains powered appliance into the Relay Box and then plug the Relay Box into a 230/240 Volt power socket.

A second “Signal Cable” comes out of the bottom of the Relay Box and this wired into a set of “Dry Contacts” (wiring points) on the irrigation controller, advanced fertigation controller or¬†greenhouse environment controller.

Most controllers send out a low voltage 12V DC or 24V AC signal via their sets of Dry Contacts.

Each set of Dry Contacts on a controller has a specific purpose. A grower therefore needs to know which set of contacts will control each particular function. The “Signal Cable” is then wired into the Dry Contacts allocated for that particular control function (e.g. heating or cooling).

When the controller sends out a 12V DC or 24V AC signal via the set of Dry Contacts, the low voltage current energises an electro magnet inside the Relay Box and this closes the circuit allowing 230/240 Volt power to flow to the appliance which is plugged into the Relay Box. The appliance then turns on for the duration of the signal (e.g 3 minutes) and then turns off.


  • The Pure Hydroponics Power Relays can function on either 12 Volt DC or 24V AC signals.
  • Appliances must be 230/240 Volt
  • Available as Single or Twin Power Relay Boxes (Twin Boxes have two sets of Signal Cables so with one or two appliances can be operated independently).
  • Maximum Current: 10 Amps

Please talk to Pure Hydroponics for pricing.