Common Wire - 2 Iros

Moving 18 zones to two Gen2 Iros. The zones were originally just run somewhat in order around the house with a mix of lawn and flower/shrub beds.

Needing 2 controllers I separated the zones between the two - one being flower beds and one being lawn.

How do I handle the common wires. I have the same 2 that are need in each box. Will it harm the Iro if I split each common wire prior to entering the controller.



@smak11, if I’m understanding correctly, you need to share both commons to both controllers? To do so, you’ll need to install some relays. However, since you only have 18 zones, I’m curious if an easier solution is to just setup each controller with it’s own common and the wires associated with said common?

I’m not sure how your wiring is setup, but if you’d like to post a few photos, we’d be happy to take a look.

Thanks, Emil

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@emil Thanks for the reply.

I do think this would be easier for the wiring. However, I would than have to manage 4 schedules to make sure they do not overlap ( lawn and beds on device one and lawn and beds on device 2). Splitting the lawn and bed zones make for nice logical split to manage between the devices and not walk on top of each other.

(pardon the blue tape. those where my notes to translate between the old and new controller(s).)

The two white wires going to the Iro on the left are the common wires. Currently the Iro on the right does not work do to the lack of the common wires.

If we could manage the two controllers as a singular system it would be easier to wire AND manage the way you are describing :slight_smile:

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Many wiring bundles have more wires than are used. If you have a spare wire use it for the common wire on the second controller and wire it appropriately in the valve control box.

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I have have two bundles and I believe both bundles have “extra” wires. Using an extra wire in each bundle might do the trick. I’ll have to check the control boxes.

I’m not sure what would be easier… [re]wiring a new control wire or setting up the relays. Need to do some research.



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Please let us know what you end up with, would love to share with other users.

Thanks and have a great day!


Using the extra wire would be much easier and cost you nothing since you already have the wiring. Just pick an unused wire, note the color, label it common (so you don’t forget), and connect the other end in the valve box to the common wire of all the valves for that Rachio (let’s say turf). In this valve box you will not need the old common wire. For the other Rachio (flowers) you can use the old common wire since it is now not connected to the turf valves.

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I took a look in the controller values and wiring… I do think the having the additional common wire will be the direction I go.

I did come across a new challenge :frowning: The system was already installed when I purchased the house. Looking at the value controller covers I can find 4 of them with 15 zones. Missing another control station the other 3 zones somewhere. I think it is buried in one on the flower beds. Good times.

I assume there is enough metal to that the metal detector will register the values/wiring bundle/etc.

Once I find that I can start the {re}wiring of the extra common wires.


Just closing the loop on this. I found my missing valve boxes.

@Khillski I went with your suggestion for wiring in one of the extra wires as a common for the other controller. Worked great. All zones working. Thanks for the suggestion.

Now to learn about schedules :slight_smile: Good times.

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