24VAC Sprinkler Relay Board Buy Now

24VAC Sprinkler Relay Board

The VG-RELAY-AC board is perfect for controlling traditional sprinkler valves or other AC loads such as low power pumps. It interfaces directly to Vegetronix soil moisture sensors. It can be wired in series to valves and block watering events from a valve clock. In addition, since it is AC powered it can directly draw it's power from the clock. It has 2 LEDs to indicate that the board has power, and the on/off state of the relay.

It is not recommended for DC or high power loads.

The VG-RELAY-AC board interfaces to a single VH400 soil sensor, and can activate a low power AC load such as a valve or alarm, or other control device, when a moisture level is reached. The threshold is easily set with the onboard variable resistor, and a small screwdriver. The relay board can be configured with a jumper to turn the relay on when the sensor detects wetness or on when the sensor detects dryness.

The VG-RELAY-AC also serves as an evaluation board. If you are thinking about testing our VH400 soil moisture sensors you should consider purchasing this board as well.

Wiring up this relay board to a valve and irrigation clock is very simple, as seen in the connection diagram below. The board is wired to a common and a valve output of the irrigation clock, and in turn it directly drives a single valve.

Take care in not allowing the valve driver outputs to short together, in this will cause irreparable damage to the relay board.

If your irrigation system drives a water pump, you should consider our Sprinkler Pump Blocker. This device will automatically turn off your pump when no valves are energized.

VG-RELAY-AC Connection diagram

VG-RELAY-AC Connection diagram, showing interface to Valve and VH400 Soil Moisture Probe.


  • Perfect for evaluating our VH400 soil moisture probes.
  • Interruption and control off irrigation and sprinkler systems.
  • Interface soil moisture sensors to home automation systems.
  • Control and monitoring of moisture content in bulk foods.
  • Rain and weather control functions.
  • Environmental control functions.
  • Water conservation applications.
  • Fluid level measurements and control.


  • Wide AC input voltage range.
  • Can be configured as a normally open or normally closed contact with a simple jumper setting.
  • Uses a low power solid state relay.
  • Can control an AC 0.6A load up to 600VAC.
  • Interfaces to a single VH400 probe.
  • Low power.
  • LED indicators, indicate power on and relay contact.
  • Terminal blocks for quick connection.
  • Low price.
  • Small size.
  • 4 mounting holes in each corner.

Relay Board Selector Guide

Vegetronix offers a variety of relay boards for nearly every application. See our Relay Board Selector Guide for help in determining which board is appropriate for your application

Other Vegetronix Products of Interest

Pricing and Ordering Info

We ship to nearly EVERY COUNTRY on the planet, directly to you from our factory.

99% of orders ship same day.

Part Number Description Price Purchase
VG-RELAY-AC AC Relay board for the VH400 probes. Interfaces to a single VH400 Moisture Sensor Probe. $35.95 Buy Now

For volume pricing contact us.


Power consumption < 40mA when relay engaged.
Supply Voltage 6V to 26 VAC (rms).
Relay Load 600VAC with maximum 0.6A load
Dimensions 1.75in by 1.75in
Number of sensor interfaces 1
Number of relay outputs 1

Wiring Table

Pin Description
1 AC or DC input 1 (max 26VAC rms)
2 AC or DC input 2 (max 26VAC rms)
Terminal Block TB2 (RELAY INTERFACE)
1 Relay contact 1
2 Relay contact 2
1 GROUND: (connect to probe ground - bare wire)
2 SENSE: (connect to probe output - black wire)
3 POWER: 5V (connect to probe power - red wire)

How to Get Started

The best way to get started is to purchase a few low cost probes and relay boards and try them out in your application.

Buy Now