No doubt about it, 2Wire systems have revolutionized the irrigation industry. They’re as important an innovation as smart controllers, sensing devices, or water-saving sprinkler heads. They vastly cut back the amount of wire needed, especially in large commercial installations.

However, like any other device or system, they will need servicing from time to time. If you don’t understand how they work, they can be baffling. Many irrigation contractors groan when faced with having to troubleshoot a 2Wire system.

Groan no more. “I actually think 2Wire is easier to troubleshoot than a conventional system,” said Ryan Seifert, irrigation superintendent at Austin Outdoor in Bunnell, Florida. “But it can get kind of tricky. As long as you’ve got a good quality install, 2Wire is a real piece of cake. But if the installer looped the wire path back to the controller, and now power’s being fed in multiple directions, you can really, really pull your hair out.”

Mark Grenert, a vice president at Wexford, Pennsylvania-based Tucor, Inc., teaches 2Wire troubleshooting classes. “At the beginning of my classes, I always ask, ‘What’s the worst thing about a 2Wire system?’…and everyone looks at me like it’s a trick question. The answer is, it only has two wires. Then I ask, “What’s the best thing about a 2Wire system?’ The answer is the same: it only has two wires.”

Let’s begin by explaining the difference. In a conventional irrigation system, you have a common wire, plus a “hot” wire. Every single valve in the system has its very own “hot” wire going back to the controller. The more valves, the more wires.

In a 2Wire system, the two wires run from the controller to the first decoder, which is installed at the first valve. Then, the same two wires run to the next valve/decoder pair. When you want to add another valve or decoder you simply connect two wires from the last two in the system to the new addition.

This should make the process of troubleshooting simpler, too. Instead of trying to sort out a snake pit of multicolored wires (that’s assuming all the colors haven’t faded after many years in the ground!) to see which one goes where, and which one is bad, you only have two wires to deal with.

And yet… “There are a lot of contractors out there struggling with 2Wire decoder systems,” said Vince Noletti, executive vice president of the irrigation and landscape lighting division at Paige Electric LLC in Fresno, California. “Most of them try to do it the same way they’ve been doing conventional systems, and they get into trouble.” First steps Before you get started, there’s one tool you must have. “You can’t troubleshoot a 2Wire system without a clamp meter,” says Grenert. A clamp meter is a milliammeter with jaws that literally clamp onto wires or connectors. “All 2Wire systems work on AC milliamperes.” These meters aren’t cheap; really good ones cost from $300 to $600. But you have to have one.

“The first thing I check is that the controller itself is putting out power down the 2Wire path,” says Seifert. “I want to see if it’s a controller issue before I ever try to chase wire.”

“After that, as long as you know the direction your wire is being fed, troubleshooting is actually very simple. I just go to the last valve that doesn’t work, then cross over to the last valve that does work. Then I go to the next one that doesn’t work, and check the power. The problem is usually somewhere in between there. I’ll break out my wire equipment and track it, narrow it down to a couple of feet where I can dig it up and replace a splice or something.”

“When I start out to troubleshoot, first I write down what the program is,” said Richie Hage, owner and president of the Bruce Hage Irrigation Company in Orlando, Florida. “I see what zones come on when, on what days, how long they run for, and so on. Then I check the fault log on the controller.” Hage’s referring to the diagnostics readout that most 2Wire systems have. You can read detailed descriptions of system faults on the controller dashboards or message screens.

An “as-built” is a map of the system. The installing contractor should produce this map of how the system was built. He leaves this with the property owner or landscape architect. It details precisely where all the decoders and wires are—in theory, that is.

However, “I’ve never seen an as-built that was accurate,” says Hage. “Usually, it’ll show how the job was supposed to have been installed, not how it was actually done. Maybe there was a construction trailer sitting where there’s normally an open field. The installers couldn’t go through it, so they just went around it. Now that trailer is gone, and so there’s this big loop of irrigation wire out in the middle of nowhere that just looks crazy.”

To make up for a missing or inaccurate as-built, a wire and valve locator can be a godsend. Similar to metal detectors, these devices work by sending signals through the earth and back up to a set of headphones.

“You track the wire path, and put some paint on the ground or plant flags to mark where everything is. Then you run through the system to see what’s turning on and what isn’t. Say zone 22 is the bad one. If you find out where zones 21 and 23 are, hopefully, 22 is in the middle, or at least in the general location.”

“However, a lot of problems are caused by installers not thinking things through,” says Hage. “They may have put zone 22 between zones 47 and 78. You can name the decoders anything you want; they don’t have to be in sequential order. Then you’re in real trouble, because then it’s like looking for a needle in a haystack.”

Substandard splices

If you’re thinking that the problem is a bad decoder, you’re probably wrong. “Eighty percent of the time, malfunctions are caused by using the wrong wire, or wire splices,” said John Hemphill, a field service manager for San Marcos, California based Hunter Industries.

“2Wire equipment is now so robust that when something doesn’t work, it’s almost always an installation problem, not a product failure,” says Kurt K. Thompson, irrigation director at Massey Services, headquartered in Orlando, Florida. “Failures often happen because an installer didn’t know any better,” says Thompson. “He did exactly what he would have done on a conventional system.”

Splices, also called connectors, are little devices that link the solenoids to the system’s wires. They have waterproofing gel inside to keep the connection dry. They’re critical components, according to Thompson. “For every ten failures that happen to 2Wire systems, nine of them will have to do with the splices.”

Splice failure can happen because the installing contractor—often in an attempt to save money—used lower quality splices, not the ones specified by the manufacturer.

“Everybody forgets that this is high voltage,” says Thompson. “Some people seem to think you can treat 2Wire systems like conventional 24-volt setups. If the contractor who installed the 2Wire system didn’t use 600-volt-rated connectors, then the gel inside either got crystallized from the constant heat, or melted and ran out. Now, you no longer have waterproof connections.”


If the problem isn’t splice-related, it could be something in the wiring. “Often, when you’ve got a problem with 2Wire, it’s because there’s been some kind of construction going on. Someone breaks or nicks a wire, and they don’t let you know,” says Seifert. “The wire gets buried again, and moisture seeps in and wreaks havoc.”

This happens more easily when non-specified wire has been used, something that servicing contractors find fairly often. “Out in the field, we often find PVC-coated wire instead of the specified polyethylene,” said Hemphill. “Someone goes to make a repair, and they’ll splice in whatever wire they have on hand,” adds Seifert.

“The reason you can’t use regular irrigation wire is because PVC insulation is porous; it actually leaks water,” cautions Bill Savelle, executive vice president, products, at Garland, Texas-based Weathermatic. “The double-jacketed polyethylene wire that we use for 2Wire is waterproof. It doesn’t leak, so you won’t get noise.”


If a decoder really is down for the count, it may have been struck by lightning. Because of the way these systems are wired, a lightning strike can travel down the entire 2Wire path, zapping every decoder in the system.

That’s why proper grounding is absolutely essential. Copper plates, rods, or a combination of both should be buried at regular intervals along the 2Wire path. How many grounding devices are needed?

“How many decoders do you want to blow up?” asks Thompson. “A ground strike might not blow up any of them—or it might fry them all.” Most manufacturers recommend putting in lightning protection about every 500 to 600 feet, at the controller and at the end of the run.

“They’re designed to isolate the damage,” says Thompson. “Say you have a half-mile of wire in each section. If there’s a ground strike, the protection would confine it just to that section, between two grounding circuits. So, you’ll lose four decoders instead of 400. It’s risk management.” Grounding should be checked every single year.


Those people interviewed stressed the value of formal training. Most major manufacturers have comprehensive training courses. “We go to as many classes as we can get to,” said Hage. There are also instructional YouTube videos, webinars and other resources that can be found on manufacturers’ websites.

Want job security? Learn to troubleshoot 2Wire. “I keep telling these kids out here, learn 2Wire and you’ll have a job for life,” says Hemphill, who has been a troubleshooter for Hunter for 19 years.

Human nature being what it is, there will always be people who’ll take shortcuts and cut corners. “Every manufacturer tells you what they want you to use: what kind of wire, what kind of splices, how to do the splices, and how to ground the system,” claims Thompson. “It only makes common sense. If you want to make sure the dadgum thing works, why wouldn’t you put it in the way that the manufacturer wanted you to?”