Craig Borland, CIC, CID, CIT, CLIA, CLWM, is a huge advocate for two-wire irrigation. “I like its technology, concept, how it works,” he says. “When you have a good quality system that has been put in correctly, it is going to last a long time. It does need some technique and a knowledge set to put it together.”
Borland, recently retired from The Toro Company where he provided irrigation technical support in product engineering, legal, marketing and landscape drip, teaches a two-wire irrigation IA University class for the Irrigation Association.
Speaking to what sets apart two-wire irrigation from conventional irrigation, Borland notes it utilizes just two wires to intermingle throughout the system. While a conventional system has a common wire connected to all the stations and a hot wire going to each individual station, “a two-wire system strictly has just two wires that go from the clock out to each valve,” he says. “The clock communicates to each of these individual valves through a decoder that turns on the individual valve according to the controller.”
Borland notes the benefit of two-wire irrigation is if a wire is compromised or cut, while everything after the compromised wire does not work, everything leading to the compromise does.
“There’s good savings on the cost of wire. You’re only digging one trench,” he says. “Another advantage is you can tie into that two-wire path and add on very easily to the system up to 200 zones depending upon the product brand.”
A significant drawback is there are more wire connections, Borland notes.
“The voltage on the two-wire path is higher than that of a standard 24-volt system,” Borland says. “It is not high voltage, but it is higher voltage – like 30 volts to 40 volts on that two-wire path. The standard, normal wire connection is not acceptable.”
The wire connection needs to be waterproof, he adds.
“The quality of that wire connection is instrumental in the irrigation system reliability,” Borland notes. “Most people do not pay enough attention to that wire connection. If it is not done correctly, you are going to have nothing but nightmares on your hands. Some 85% to 90% of the problems in two-wire systems are due to a poorly made wire connection.”
The use of two-wire irrigation has expanded from commercial use to residential use because it offers the same advantages, Borland notes, adding because the system will work to the point of a compromised wire, it makes it simple to pinpoint a problem’s exact location.
For those concerned about costs, Borland notes each manufacturer’s product is different.
“The key is if I use a specific brand controller, I must absolutely use that same brand decoder for the system,” he says. “If I have got 200 stations out there, I am going to have 200 decoders out there. Decoders are not inexpensive. Now it is the cost of the clock and the cost of the decoders, and they are brand-specific and vintage-specific.
“Some brands have been updated over the years. That means you have to use the decoders that correspond to that brand’s controller, so that adds to the cost factor. The main savings is you only use two wires.”
In determining which brand would be appropriate to use, Borland notes many manufacturers offer some form of two-wire irrigation set-up. “The best brand is the one that contractors are familiar with and has good support, because they’re going to need to ask them for their help in putting it together,” he says. “Learn the nuance of each brand’s idiosyncrasies.”
The control product can save water by adjusting its irrigation schedule according to weather and to the moisture in the soil, Borland says, adding many two-wire systems now have the ability to add moisture sensing to the two-wire path.
“If you have a clock that gets information about the weather from a local weather station, internet or serial cable coming in from a cell card, the clock will adjust its schedule according to the weather,” says Borland.
Best Management Practices
Addressing best management practices entailed with two-wire irrigation installation, Borland says the first consideration is getting to be proficient in making a waterproof wire connection.
“That means when you are making wire connections, do not pre-twist the wires before you put the wire connection on. Let the wire nut/connector twist the wires for you and take the wire connector and push it all the way to the bottom of the waterproof tube,” Borland says.
Some wire connectors come with pre-filled gel in them.
“You still take the wires, get them all put together, cut the wire so they’re all equal in length, gently push them into the wire connector with the waterproofing, and let the connector twist the wires for you,” says Borland.
“You have to make certain the wires are twisted equally. Tug on each wire separately so no wire comes out. Get it all the way to the bottom of the waterproof tubing. Many times, the wire connection and the wires do not want to go in all the way to the bottom of the tube. Grab a sprinkler flag or a marker flag and help push the wire all the way to the bottom of the tube and then swirl the flag as you pull it out of the tube, so you do not have a hole left behind as you pull the flag out. Every brand has the same requirement for a quality wire connection.”
Contractors should understand how to program the decoder in a manufacturer’s controller – some are easier to do than others, Borland says.
“Many manufacturers offer a hand remote programmer that you can program the decoder outside of the controller,” he adds. “They are also brand-specific. Every brand has a decoder that needs to be set up in the controller one way or another. You have just got to put that in the controller and then run the wire.
“I can’t stress this enough – when you run your two-wire path, put it in conduit. A lot of people just take the wire path, throw it in the ground and call it good. If that wire gets damaged or compromised in any way, if it is not in conduit, you have to replace that wire.”
Warranty concerns include grounding, two-wire product, decoders and wire connections. Following the recommendations of the company through which the two-wire irrigation system is sourced is key to adhering to warranty considerations, Borland notes.
While some companies may say existing wire can be used, the integrity of the wire is important, Borland says. He recommends 14-gauge or 12-guage wires.
“The key difference between two-wire and conventional wire is the two-wire path is live in many cases 24/7, 365 days a year, meaning there’s power on it all the time. The amperage going through that wire path is on all the time,” he says.
“If you have a compromise on the wire, you’re going to have corrosion occur quickly and that corrosion evolves into oxidation and becomes that white or green-colored crispy stuff to where the copper dissolves and vanishes due to the electrolysis.”
That can happen quickly, Borland adds.
Proper Grounding
Grounding also is critical, he says.
“I can’t stress enough if you’re in an area that doesn’t get lightning, you still need to ground it for the warranty of the manufacturer,” he says. “You need a grounding device every 600 feet or at the end of each run. That grounding could be a ground rod or ground plate with either a surge protection device connected to it or connected to the decoder’s ground wire.”
Borland notes that according to the National Electric Code, a ground rod or ground plate needs to be away from the device that it is protecting by the length of the rod or the length of the plate.
“If you’ve got an 8-foot ground rod, that ground rod needs to be 8 feet away and perpendicular to the wire path. It makes it a little complicated – especially in turf areas – but you’ve still got to do it,” he adds.
Borland recommends putting at least a 6-inch round valve box around the top of the ground rod so someone can find it if there is an issue with the ground.
“Any wire connection needs to be in a valve box so that you can find it as well in case it needs to be replaced,” he adds. “The quality of the wire connection is paramount. Each wire connection ever made will be replaced. My goal is to make a wire connection so the next generation has to replace it.”
The wire connection quality also is paramount in installation – the brand-specific decoder to the brand-specific controller, says Borland.
“There’s a brand that has decoders built into the solenoid, which makes that a little easier,” he says. “Nonetheless, that solenoid decoder combination still has to be programmed.”
Troubleshooting
Two-wire troubleshooting starts out with determining if there are correct volts on the two-wire path at the clock.
“If you don’t, remove the two-wire path and check it to see if that voltage returns. There may be a problem on the two-wire path that can damage the clock,” says Borland. “Ohm check the two-wire path. It should be an open line. If you have any resistance, then there’s a problem on that two-wire path. It can be a bad decoder, a bad surge protector or a wire short circuit.
“Then do a current/milliamp test. It’s got to be a current leakage meter that can read milliamps. Most clamp meters do not read that low of current range. Buy a milliamp or a leakage current tester. Measure the current draw of each decoder. Each decoder pulls roughly 0.5 to 1.2 milliamps each. If it’s four-station or higher, it’s going to be one milliamp to 1.5 milliamps each. If it reads higher, it is a bad decoder.”
Begin with determining if there’s voltage coming out of the unit, Borland advises.
“If you don’t have the voltage, remove the two-wire path from the clock,” he adds. “Try the voltage again. The voltage returns. The clock’s good. There should be an open line when testing for ohms.
“If you have ohms of resistance, you’ve got a problem on that path and you’ve got to track down where the problem lies.”
Borland notes the apprehension many contractors may have over installing such systems is rooted in a lack of understanding and familiarity with it.
“There is a little more involved with installation, but once it’s in and running, if you’ve got a good two-wire system, it’s an incredibly reliable system,” he says.
Borland notes that two-wire irrigation will continue to grow in popularity in the industry “the more people get comfortable with it and realize making that wire connection is really not all that hard. It’s just different.”
Major manufacturers of two-wire irrigation systems include Rain Bird and Hunter Industries, both of which offer comprehensive training and support for contractors interested in learning more about these systems. For those seeking professional certification, the IA Certification Programs offer credentials like those held by Borland (CIC, CID, CIT, CLIA, CLWM).
