In a 24V irrigation system, what is the role of the common (C) wire and the zone wire?

• A. C wire powers the controller; zone wire powers each valve.
• B. Zone wire completes the circuit for each zone; the common (C) wire is shared by all valves.
• C. Zone wire is common; C energizes each valve.
• D. No C wire; each valve has a separate circuit.

Answer: (C)

In a 24V irrigation system, each valve is a 24V solenoid that needs two connections. One side comes from the controller via the zone wire, and the other side is the common conductor (C) that is shared by all valves. When a zone is activated, the controller sends 24 volts through that zone wire to the valve. The current then returns through the common wire back to the transformer, completing the circuit. Because the common is shared, all valve coils connect to the same return path. This setup means the zone wire provides the energizing path for a specific valve, while the C wire provides the common return for all valves.