2-Wire vs. Conventional

Columns - Irrigation Issues

May 7, 2018

Occasionally, I feel compelled to revisit the controller-versus-decoder (2-wire) comparison because it is an ever-evolving issue. Why now? Well, in 2017 a significant milestone was reached in that more new/replacement golf course irrigations systems were installed utilizing 2-wire control systems than with conventional satellite/field controller control systems, according to the major manufacturers. The world of golf course irrigation control is changing.

Decoder systems have been around for many years, but the newer-style decoder systems, now referred to as 2-wire systems, started with the introduction of Rain Bird’s Integrated Control Module (ICM) system in 2008. Two-wire systems operate on 2-wire paths for all the sprinklers, as opposed to a control and common wire for each sprinkler/solenoid. This saves considerable wire, however, the 2-wire communication cable cost per foot is much more expensive than the control and common wire costs are per foot. Much of that cost savings is also eaten up by the additional grounding requirements necessary in a 2-wire system. While conventional wired irrigation systems are relatively robust, 2-wire systems are much more sensitive to wire nicks, poor splicing and shoddy installation practices. So why the shift?

Two-wire systems have lots of advantages, the main one being technology. Two-wire technology allows for features not available with a system that just sends a signal down a wire. Two-wire systems deal more with data type signals. The most obvious benefit of 2-wire technology is the ability to operate hundreds of sprinklers at the same time anywhere you want on the golf course, limited only by the irrigation systems pumping and piping capacity. Most conventional systems are limited to a maximum of 16 solenoids at the same time per controller. Two-wire systems also have the ability to do a great deal of self-troubleshooting that is extremely accurate, pinpointing very closely the location of a problem. This is accomplished by monitoring voltage and, in the case of some manufacturers, amperage at each sprinkler/module.

Another advantage to a 2-wire system is there are no controllers sticking up out on the golf course, which is desirable on links-style courses or courses subject to vandalism or flooding. However, the 2-wire technology’s biggest advantage is that it continues to evolve allowing the manufacturer to add additional features to your system in the future. This is not possible with a conventional signal type control system. Since you are making a long-term investment – 20-plus years – the ability to update your system without replacement should be very attractive. Some things that could be/are a possibility:

  • Confirmation of whether the sprinkler popped up or down
  • Pressure at the sprinkler
  • Flow at the sprinkler
  • Arc setting
  • Arc adjustment
  • Switching from part-circle to full-circle

Of course, there are also disadvantages to the 2-wire system. For example, if you damage the communication cable, then the system is not operational downstream of the damage. Also, if you lose the computer, then you cannot operate. And 2-wire systems are very sensitive to lightning and power issues. Conventional systems have much more redundancy as there are field controllers/satellites which you can operate from if you lose the computer or communication signal. On a 2-wire system you can mitigate these issues somewhat, but it is expensive and reduces some of the advantages of having 2-wire in the first place.

The most important decision on which control system to purchase should be based on is your management style. If you are used to walking up to a controller and making changes, are uncomfortable with technology, or like lots of redundancy, then 2-wire is not for you. If you are used to operating your system only from the remote or central, don’t know where your controllers are located or love apps, then 2-wire is probably what will work best for you.

Finally, keep in mind that at some point there will be another person in your position and what will they want. What is best for the course long term?

These are exciting times for golf course irrigation control systems. While 2-wire systems have the downsides of most technologies in terms of sensitivity and new things to learn, the ability to upgrade and improve your system over time without massive hardware changes and their associated costs is very appealing.

Brian Vinchesi, the 2015 Irrigation Association Industry Achievement Award winner, is President of Irrigation Consulting, Inc., a golf course irrigation design and consulting firm with offices in Pepperell, Massachusetts and Huntersville, North Carolina that designs golf course irrigation systems throughout the world. He can be reached at bvinchesi@irrigationconsulting.com or 978-433-8972 or followed on twitter @bvinchesi.