You cannot connect two controllers sharing the same common wire directly. This can lead to severe damage to the controllers and equipment and it is a violation of the National Electric Code. This can be done only by following this provision.
Parts needed: an ISOLATOR for each RainMachine used. (Get 15% off using code: RAINMACHINE)
The Isolator includes a pair of relays which allow only one controller to access the pump or valve circuit at a time to prevent feedback between controllers and damage to controllers due to incorrect phasing.
Unplug the RainMachine controllers.
Wiring between Isolator and the RainMachine
The wires from the left side of the controller (black&white) will be connected to the RainMachine. The black wire goes to the Master valve (Zone1) connector and the white wire goes to one of the Common connectors.
Repeat this step for the second controller with the second Isolator.
| Black ->
Wiring between Isolators and field valves
The wires from the right side of the controller (red&white) connect to the Master valve wires. The red wire goes to the hot wire of the valve and the white wire goes to the Common wire of the valve.
Repeat this step for the second controller.
|| Field Valve
Note: Using Isolators will allow two RainMachines devices to water at the same time. Running 2 different zones (one from each RainMachine) at the same time can affect your water pressure.