Identifying the Common Wire When Replacing an Irrigation Controller

Wiring a New Orbit 4-Zone Timer to Existing Valves

Replacing a Richdel 300 series controller with an Orbit 4-zone timer. The old wiring had green, yellow, red, white, and blue wires. Green was connected to common, yellow/red/white to zones 1–3. The blue wire blows the fuse when connected to any zone.

Find the True Common Wire

At the valve box, each valve has two wires: one unique "zone" wire and one shared "common" wire. The common wire is the same color for all valves. Identify that color at the valves—it's often white, but not always.

Correct Connection

1. Connect the identified common wire to the new controller's COM terminal.
2. Connect each valve's unique wire to a separate zone terminal (1–4).
3. Any extra wires not connected to a valve should be capped off and left unused.

The blue wire is likely a spare or an old master valve wire. If it's not connected to a valve, do not connect it to the controller.