Installing two 16-zone controllers for one sprinkler system

[tmcgahey]

There is a way to share common wires between controllers. This is above explaining from me today (thank God it’s Friday), but you can read through this thread.

Multiple Rachio Controllers with Shared Command and Master Valve

Perhaps it would be helpful to think of isolation in terms of the bird on a power wire. As long as the bird is touching only one wire, it is safe no matter the voltage within the wire itself. Sharing a single wire (commons) between multiple controllers, is like multiple birds sitting on the same wire. As long as birds are leaving each-other alone, we can have peace and quiet. Isolating commons, such as with your original configuration is like shooing one of the birds away when the second one ne…