Wire right

Troubleshoot low-voltage lighting installations with these 4 tips.
Photos: Irrigation and Lighting Specialties

While your business might focus on landscape maintenance or design, and not irrigation or lighting systems, the likelihood of needing to make a wiring repair in the field or troubleshooting an electrical issue throughout the course of a season is high. While larger jobs are best left to wiring pros with more experience and more extensive knowledge, a basic understanding of low-voltage wiring will ensure that fast fixes and small jobs don’t turn into wiring nightmares for both you and your clients.

Approach with caution

The number one rule of thumb when working with electricity is to always use caution, and working with low-voltage wiring is no exception. Despite its seemingly innocuous name, low-voltage wiring can deliver big shocks and cause significant damage if it isn’t done correctly.

“Just because it is low-voltage lighting, it doesn’t mean it is free of risk,” says Ben Harcey, service director of Designs by Sundown in Denver, Colorado. “Because it is low voltage, it can actually accumulate more resistance in the lighting system than in a traditional 120-volt system. The biggest hazard is fire damage if there is too much resistance at a wire splice location or at the transformer.”

As a green industry professional, low-voltage wiring is something you’ll undoubtedly encounter in a variety of settings. You’re at a job site, digging a hole for new plant material or excavating for a new tree installation. Next thing you know, you’ve cut a buried wire, and it needs to be repaired. While it’s possible to splice wires back together and get the system to function, there is actually a right way, and a wrong way, to make that repair.

The number one rule of thumb when working with electricity is to use caution, even when it’s low-voltage wiring. Be careful in handling and repairing wiring to avoid shocks and fire damage.

“You’re going to cut a wire, it’s going to happen to the best of them,” says Chris Fry, CIC, CIT, CLVLT, and owner of Irrigation & Lighting Specialties LLC in Charleston, South Carolina. “I’ve cut them 1,000 times. You’ve got to make the repair, and it’s how you make that repair that determines whether the system is going to work correctly.”

The high chance of needing to make a wiring repair is why Fry recommends carrying an emergency repair kit in the truck, complete with the materials to properly complete repairs.

“Buy and have handy in the truck wire splices that are gel filled and rated for UL 486,” Fry says. “Have wire in the truck in three different sizes — 10/2, 12/2 and 16/2 — along with different splice sizes and wire strippers.”

Much like other products, there is imported wire on the market that isn’t up to code. Wire that is UL Listed is the industry standard when it comes to landscape lighting, and Fry says “UL Listed” will be printed onto the casing of the wire.

While big box stores do sell UL Listed wire in select sizes, Fry recommends shopping at a local wholesaler, who can provide much more than a few rolls of wire.

“You can get by with buying from a big box store for your truck’s repair kit, but the counter staff at a local wholesaler will be a good source to answer any questions,” Fry says.

Don’t scrimp on materials

When it comes to materials, Sean Curran, CLVLT, and owner of Beautification Through Illumination Inc. in Amesbury, Massachusetts, says many contractors will try to save money on materials, which can impact the longevity, functioning and safety of an electrical system.

According to Curran, wire connections are a key point of failure in many systems, especially as fixtures from big box stores often include quick-connect devices for installation.

Making sure the seal is tight and unbreakable is the key to making a repair that will last.

“A lot of companies are giving people a quick connect, a very small connection device where you lay two wires, then snap a plastic connector with a couple of corrosive pins that pierce the coating of the wire,” Curran says. “Over time, moisture will get in there and corrode those two small pins, which will eventually lead to failure, especially when you’re drawing a lot of power, and especially in an acidic soil like we have in the Northeast.”

Some inexperienced contractors will choose wire nuts, which, while well-suited for interior work, lack the key attributes required for outdoor wiring: metal-to-metal contact, extremely tight connection and waterproof.

“A lot of times, people will use the wrong connection devices, like a standard wire nut with no gel fill or protectant, then wrap electrical tape around it,” Fry says. “That’s a no-no. With water intrusion and corrosion, the system will start to trip.”

Making sure the seal is tight and unbreakable is the key to making a repair that will last.

“You don’t want to be able to pull the connection apart once it’s together,” Curran says. “A lot of us use a brass barrel with a heat shrink tube over it. Using a quick connect is a point of failure in all systems. They don’t save time, they don’t save money and they cost you money in the end.”

You don’t want to be able to pull the connection apart once it’s together. A lot of us use a brass barrel with a heat shrink tube over it. Using a quick connect is a point of failure in all systems.
– Sean Curran, Beautification Through Illumination

Curran says he also sees contractors using a smaller-gauge wire than they should, likely because they don’t have a complete understanding of electricity.

Make certain to use the right size wire and splices, as well as the correct mounts for the job. Using the wrong materials is a quick way to develop a safety risk.

“It’s a matter of sizing the cable with the transformer you’re using,” Curran says. “A lot of contractors try to save money by using a smaller-gauge wire than they should, but what they don’t realize is if they’re using a 300-watt transformer, which is pretty popular these days, a 300-watt transformer has a 25-amp secondary breaker in it. They will tend to use a wire that isn’t rated for 25 amps, which means that if a wire gets cut or crossed it cannot send that resistance back to the transformer to have the breaker trip, and you can cause a fire anywhere along where that cable is.”

As the cost of materials have steadily increased, Curran says consistently downsizing the wire could result in savings at the register. But the safety risk far outweighs any savings, as Curran says the power of 25 amps of electricity can make a wire glow red, melt the coating and ignite anything combustible nearby.

Understandably, those who aren’t working with low-voltage wiring on a regular basis might not have the knowledge or experience necessary to properly calculate things like voltage drop or to both use and understand the readings from an amp meter, which is another great reason to seek out education and training from distributors, manufacturers and associations.

“Some contractors don’t understand the more detailed side of it, and if the lights work, they walk away,” Curran says.

When he’s called to make repairs to the repairs other contractors have made, Fry says he often notices another mistake that is easily avoided with some knowledge, a lack of slack in the wiring.

“You need to add at least two feet of wire so you have a foot on either side,” Fry says. “If the wire was cut during excavation for a new tree or landscaping, you’re going to need the extra foot or two on either side to relocate the wire around the new landscaping.”

Pay attention to polarity

You’ve used a high-quality, UL-Listed wire and the proper connectors, yet the breakers are tripping when the system switches on. It’s a frustrating but common mistake.

“I had a customer with two fixtures from a big box store, and after the homeowner wired them in, they started tripping breakers,” Fry says. “He wasn’t paying attention to polarity, which is a wiring issue that can happen when you make a new splice. You can connect the wrong wires together and get the polarity backwards. That’s a big issue.”

In addition to serious safety concerns, Fry says reverse polarity will cause a dead short, which is when the fixture will turn on for a spit second, then trip both the breaker and the transformer.

Know what you don’t know

As the popularity of home improvement and remodeling shows soars, so does the mentality that “if my neighbor did it, I can do it,” Fry says.

“We love those homeowners because they give us lots of work,” Fry jokes.

With confidence boosted by television shows, books and kits from big box stores, many homeowners, and contractors, think they can tackle tasks better left to more experienced professionals. One common misconception is that LEDs are quick and easy to install.

“While you don’t have to deal with voltage drops as much with LED fixtures, it is something you need to be aware of,” Fry says.

Quality is also important when it comes to LED fixtures, as it can have a major impact on the longevity of the system.

“I see a lot of LED bulbs going out prematurely because of moisture versus the older halogen systems,” Fry says. “With the connections in some of the fixtures, the quality of LED lamps need to be of a higher caliber.”

While you might not know all the ins and outs of working with low-voltage wiring, Harcey says there are many resources available to irrigation and other green industry professionals who can be easily cross-trained with the help of things like manufacturer training programs, sizing charts and other educational opportunities.

“Your staff and team are already good with shovels, good with tools, understand the basics of troubleshooting a system and laying out a system, and that experience directly correlates and converts to the lighting world, Harcey says. “There’s a good chance that your same distribution centers that stock irrigation and landscape materials will be your go-to vendor for lighting, and there’s a good possibility they will also provide classes, consulting and design support for the contractor as well.”

Lauren Sable Freiman is a freelance writer based in Cleveland and can be reached at laurensable@gmail.com.

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