I am attaching a Toro RainSensor which has 1 red and 1 black wire to an old Hydrotek system. I am not sure where to put the wires. In the photos, the wires coming into the box from the left go to my electric, and the wires going out to the bottom right from the transformer go to the water switch.

I suspect I have to put the sensor between the currently connected blue / white wires on the right (I am assuming the white wire is the "common" wire and the black wire is the "hot" wire - United States). And yes, I will flip the breaker switch off before attempting any of this (and did so for the photos).

Photos (click for full-size image)

Two instructions from the RainSensor instruction booklet



Instructions from the Hydrotek


3 images of the current box wiring interior

wiring wiring wiring

1 Answer 1


I pulled apart the blue-to-white from the transformer to the water on/off switch, and put sensor's black to transformer's blue, and sensor's red to switch's white.

Then I flipped the power on and turned the system on. It ran fine. I pressed the manual test sensor switch while it was running, and the system stopped. Installation complete.

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