SPRINKLER TALK FORUM - You Got Questions, We've Got Answers

I was under the impression that typical (residential) irrigaion valves and controllers are designed with AC power in mind (low voltage, but still AC). So there is no such thing as positvie and negative.

The typical (residentail) controller only has one "common" terminal with each valve having its own "control" terminal. The basic idea is that you will likely have a manifold and the controller will only allow one valve on at a time. So rather than running a seperate "common" wire for each valve, allow them to share a "common" wire so you have fewer wires to run between the controller and the manifold. The only situation where I could see having a controller with a "common" terminal for each zone is one designed for a distributed system (say like a golf course) where there isn't a single manifold but the valves are instead spread out. In that situation, you are more likely to have to bring a pair of wires from each valve all the way to the controller. So I could see a professional controller having two terminals per zone for that sort of setup.

continuous power