Wiring a Replacement Timer: Common Wire & Zone Connections

Replacing a Richdel 300-series with an Orbit 4-zone timer? The wiring is standard once you identify the common.

Wire Identification

• White = Common (COM) — connects to ONE wire from EACH valve solenoid.
• Yellow, Red, Green, Blue = Zone wires — each connects to the OTHER wire on its respective valve solenoid.

Your Setup

5 wires for 3 zones means: 1 common (white) + 3 zone wires (yellow, red, green) + 1 unused (blue). The blue wire is likely a spare or for a future zone/master valve.

Orbit Timer Connections

1. White wire → COM terminal
2. Yellow wire → Zone 1
3. Red wire → Zone 2
4. Green wire → Zone 3
5. Blue wire → Cap off / leave disconnected (unless you have a 4th valve or master valve)

Blown Fuse Cause

Connecting a zone wire to COM (or shorting two zone wires) creates a direct short on 24VAC → blown fuse. Always verify: each valve has two wires—one goes to COM (shared), one goes to its zone terminal (unique).

Verify at the Valves

Open each valve box. Confirm: one wire from each solenoid connects to the same wire (white) — that's your common. The other wires are your zone wires.