How do I install a rain sensor? (Generation 2)


For more detailed information, see Rain Sensors FAQ. In most installations, a rain sensor acts as a switch; as moisture absorbing disks expand, they activate a switch that interrupts the circuit from the controller to the solenoid valves. Once the rain sensor has dried out, the switch deactivates to allow for normal operation.

The Rachio 2nd Generation Smart Sprinkler Controller is compatible with any wired or wireless normally closed (NC) rain sensor, which activates after rainfall (when the moisture-absorbing disks expand).


The Rachio 3 Smart Sprinkler Controller and the Rachio Generation 1  Smart Sprinkler Controller are also compatible with any wired or wireless normally closed (NC) rain sensor.
For Rachio 3 sensor wiring instructions, go here. 
For Generation 1 sensor wiring instructions, go here.

Installation Guide

Prior to installing the Rain Sensor, take a few moments to read through these instructions in their entirety. The rain sensor must connect ONLY to the following terminals on your Rachio Smart Sprinkler Controller, Generation 2 device:

  • rain sensor ( S1 , S2 ) terminals - use S1 or S2, NOT both
  • sensor common ( SC ) terminal
  • sensor power ( SP ) terminal - for wireless (powered) sensors

Do NOT connect the rain sensor to any of the zones.

Installation methods must comply with all applicable national and local electrical codes. If you are unsure about proper wiring practices, have a qualified contractor perform the installation for you.

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How To Connect Rain Sensor Wiring

1) Disconnect power to the controller.

2) Route the Rain Sensor connection wire into the controller through the access hole in the base or bottom of the unit

3) Locate your controller's sensor terminals (SC & S1, S2) and attach the Rain Sensor control wires directly to these terminals (in either order) -- see diagrams.
4) Reconnect power to the Rachio controller.

5) Enable the rain sensor in the Rachio App Controller Settings


Avoid routing the wire over any sharp edges where damage to the wire insulation may occur. For best results, hide the wire as much as possible by tucking it under shingles and/or moldings. Seal any holes made by passing the wire through structure walls.

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Rain Sensor Wiring Diagrams

a) Wired Rain Sensor (basic non-powered)

To connect a wired rain sensor to your Rachio 2nd Generation controller, please see the wiring diagram below: 

b) Wireless Rain Sensor (powered transponder)

To connect a wireless rain sensor to your Rachio 2nd Generation controller, please see the wiring diagram below: *wire colors will differ — find model-specific diagrams in links below:

Supported Rain Sensors (Click name for Specs & Instructions)


Either terminal "S1" or "S2" can additionally be used for a flow sensor. Configuration in the app allows you to assign a rain sensor or flow sensor to either terminal.

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Enable in App

To activate the rain sensor in the Rachio app, please follow the steps below:

1) From the Home screen, select the "More" tab and then "Controller Settings." 

2) Go into "Accessories", then select "Sensor (S1 Terminal)". You may only add a rain sensor to this terminal if there is no one currently installed. If there is a sensor installed, select "Sensor (S2 Terminal)", the option below S1. 

3) Enable the sensor by toggling it on.


4) Select the type of sensor you're adding (in this case, "Rain").

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Check if it Works

To test the Rain Sensor operation, please review: How to test a rain sensor

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