Head groundskeeper Dan Ochsner (left) and JC Wheaton, manager, Centerville Landscape and Irrigation, Inc. at the Dayton Dragon’s home field.

Ochsner employs two-wire irrigation system in Dayton

For the past nine summers, the hottest tickets in Dayton, OH have been for the Dragons, one of Minor League Baseball’s most popular teams. In fact, Sports Illustrated magazine named the Dragon’s home field one of the “Top Ten Hottest Tickets To Get” in all of professional sports. That’s because since 2000 (when the stadium opened), the Dragons have sold out all 9,000 seats and earned their fans’ loyalty by making Midwest League playoffs nearly every year.

While doing patchwork, JC and his crew discovered that the old system was a “rat’s nest” of re-spliced wires, riddled with in-ground connections that weren’t even close to the valve boxes.

“Dan and I decided to finally fix it once and for all. That’s when we started talking about two-wire.”

Wheaton’s Centerville crew had hands-on experience with two-wire, using it on new commercial installations and irrigation system expansions. They were ready for the sports field challenge.

“After doing the math, we found that retrofitting the ballfield with two-wire would prove to be much more cost-effective than pouring money into the existing faulty electrical,” he said.

How two-wire works

Two-wire irrigation control systems use just a single pair of wires that extend from the controller to each valve sequentially in the irrigation network. The two-wire path can be branched in any direction that works best for the site.           

“In a conventional, multi-wire installation, we’d dig trenches to accommodate wiring from the controller to each station, then extend the common and run a hot wire back to the controller,“ said Wheaton, “with costs adding up for labor, wire and materials.

“However, we found that systems with over 300 feet of mainline cost less when installed with two-wire and they are easily expandable.”

The ability to add valves at any time and anywhere along the two-wire path is one of the system’s best-known features—with no new wire, retrenching became a problem from the past.

“Installing two-wire also doesn’t require any special equipment or tools, so we could use the same valves that we were familiar with and the same solenoids and waterproof connectors that were already on our trucks.  Even the line is typical irrigation wire,” said Wheaton.

Wheaton’s crew was trained in two-wire last fall on a range of commercial sites.

“They picked it up in a day or two…it’s very intuitive. And they were happier pulling just two wires, rather than old school multi-wire.”

Back at the ballfield, Wheaton and Ochsner decided to go with an Underhill 2Wire system. They brought in a new Hunter ICC Controller, but kept the Hunter I-25 and I-40 rotors, along with the 2” HBV (Hunter brass valves).

Hunter’s ICC is completely compatible with the Underhill’s 2Wire Decoder Module, the brains behind a two-wire system. They also ran new wire and connected the valves to the two-wire system with Underhill’s 2Wire Decoder Receivers.  A Hunter rain sensor was added for improved efficiency.

Renovation started April 1, 2008 and was completed in 4 work days, with a little juggling around the Dragon’s spring schedule.

Since the entire system was going two-wire, when the new ICC was installed, the crew just snapped the Underhill ICC Decoder Module into the first module slot. (Underhill 2Wire also offers the option of mixing an existing multi-wire system with 2Wire Decoders and valves. In that case, the Decoder Module locks into a secondary slot on the ICC. For all other controllers, Underhill also has a Universal Decoder Module that is compatible with any commercial timer.)

To verify the ICC module was correctly inserted, the installer pressed and held the Push button until a green LED programming light flashed to indicate the Decoder Module had been correctly mounted. All 13 stations were then enabled.

Electrical Surge Protection

Both the ICC and 2Wire Decoder Module are equipped with built-in electrical surge protection. The Decoder Module was connected to a ground rod with less than 10 Ohms resistance. The crew used a #10 bare wire to connect the controller to the ground rod, and the ground terminal was located next to the main two-wire cable terminals. No grounding was required for the 2Wire valve decoder/receivers along the main two-wire path.       

Each valve decoder/receiver was set with a unique station address before the decoders were installed. That way, when the controller turned on a decoder station, it sent power down the main two-wire cable along with a digital signal (the address) that was specific to each valve decoder. As the decoder/receiver heard its address, it applied voltage to the solenoid, completing communication from the controller to each station.

All Fifth Third Field valve decoder/receivers were programmed with Underhill’s portable Programmer/Tester. There is also a built-in decoder programmer on the ICC Decoder Module, which allows the installer to program a valve decoder station number by inserting red and black decoder wires into the ICC Decoder Module.

Connecting Valves and Decoders

The Centerville crew routed the main two-wire cable between each control valve location and the ICC. At the valves, they cut the main cable and stripped back the outer insulation 4” on each cut end. They then stripped each conductor ½” and the four wires on the decoder ½”.  After they spliced the decoder’s red and black wire into the main cable, they connected the decoder’s red wire to the main cable’s LI conductor and the black to the L2, then attached each of the decoder’s yellow wires to each solenoid wire valve. All wire splice connections were done using waterproof connectors.

Back at the ICC Controller, they routed the main two-wire cable through the conduit and attached the conduit to the controller at the large portal at the right side bottom of the cabinet. They then stripped ½” of insulation from ends of the main two-wire cables and secured each conductor into the bottom two terminals of the ICC Decoder Module. They finished by connecting the conductor with the decoder’s red wires to LI and the conductor with the decoder’s black wires to L2.

Ochsner reports they’ve had great luck with the system, which runs the irrigation every evening with water from an on-site well. He has five zones of 180° heads on the perimeter, running for 10 to 18 minutes, and eight zones of 360° rotors on the field, typically irrigating for 20 to 30 minutes.

Ready for all kinds of Midwest weather, the field is turfed with Kentucky bluegrass, overseeded with perennial ryegrass and has an efficient sand-based rootzone drainage system. Drain lines are set 18 inches below grade, running parallel at 25-foot intervals.

“My only two-wire recommendation is that the irrigation installer prepare a detailed system plan that identifies each valve and decoder and the overall number of zones. This will save hours of time during troubleshooting, such as locating bad solenoids or identifying non-working zones,” said Wheaton.

“Other than that, we have had a great success rate with 2Wire systems.”


Two-Wire System Overview: How It Works     


• Only one pair of two wires run from the controller to each valve in the system.

• 24 VAC power and address signal are sent over the same pair of wires.

• Valves are installed along the two-wire path. Each valve has an individual “decoder” (or receiver switch) installed within it.

• Each valve decoder/receiver has a unique address that identifies it to the controller. Signals are sent to each valve decoder/receiver from the controller telling it when to open or close.

• Any existing or new commercial controller can easily be converted to two-wire operation with up to 63 stations.

Two-Wire Terminology 


ICC Decoder Module – Snap-in module that mounts inside a Hunter ICC commercial controller and  which sends a programming command to a valve telling it when to turn on or off, based on the programs within the ICC.

Universal Decoder Module –  Module that connects to any controller’s terminal strip. These modules can be mounted internally within the controller or externally, up to 3,000 feet from the controller.

Universal Sender –  An interface module that is connected between the controller’s terminal strip and the two-wire path.

Decoder – An electronic receiver that is connected to each valve in a two-wire system. The decoder/receiver picks up on/off commands initiated by the controller. The decoder/receiver address is set during installation to correspond to the controller’s station number.


Where to Use Two-Wire


Two-wire is used on sites where the costs of installation and maintenance are a consideration, typically systems with over 300 feet of mainline, including sports fields; parks and recreation centers; college athletic fields; sports complexes; hotels and resorts; highways and median strips; homeowner association common areas; cemeteries; commercial centers and public facilities; nurseries and tree farms; golf courses; parking lots and plazas; medium to large residential and commercial projects.

Two-wire is also recommended for use on sites that might be installed in phases or unexpectedly expanded, such as a community sports facility or college sports complex.