The truck is loaded with essential equipment, like a vibratory plow and a trencher. The call to 811 has been made to ensure safe digging, and there is an understanding of the National Electric Code (NEC) requirements for Class 2 low-voltage circuits. It’s time to head out for an irrigation installation. Or is it an outdoor lighting installation? It could be either one — or both.
According to professionals who install both outdoor lighting and irrigation systems, these similarities across the industries are a major plus in the case for combining irrigation and lighting in a single mobilization.
“As an irrigation contractor, we are dealing with water and piping, but also with electricity and electrical runs, and we have to meet the same codes the outdoor lighting industry has to meet,” says Chris Fry, CIC, CIT, CLVLT, owner of Irrigation & Lighting Specialties in Charleston, South Carolina. “When you start looking at codes and what is required, irrigation and outdoor lighting are both categorized as Class 2, according to the National Electric Code. We have the same parameters as far as depth of wire and the kinds of wire connections we have to use, and we have the same codes for going through walls of homes and garages.”
Although the requirements and codes for installing outdoor lighting and irrigation are nearly identical, there are some nuances and slight variations between the two. Understanding the differences will help ensure that any irrigation and lighting installation meets requirements, withstands environmental factors and leaves customers satisfied.
Use the NEC as a guide
According to Fry, adherence to NEC codes should be standard practice in both the lighting and irrigation industries. Specifically, NEC Article 411 refers to low-voltage systems, while Article 300 dictates depths for underground installation of wires and piping. Article 300 requires the following depths: 24 inches for sleeves under roads and driveways, 18 inches for trenches for piping and 6 inches for wires.
“When you look at these articles of governance, outdoor lighting has the same requirements as the irrigation standards,” Fry says. “That’s why you’re seeing irrigation contractors getting into the lighting industry. A lot of times, irrigation systems are even a higher voltage — not high-voltage, but higher than outdoor lighting systems.”
Because irrigation professionals are usually on the job before lighting contractors, Fry says sharing trenches is not only cost-effective and efficient, it also makes sense from a maintenance perspective.
“If your pipe trenches are already 18 inches and wire only needs to be buried 6 inches deep, why not lay in the deeper trench? You will save time and labor, and it helps prevent damage to lighting wire, especially in those large spans of open turfgrass,” he says. “This will help prevent damage to lighting wire from aerification and mechanical edgers.”
Fry cautions that, when using shared trenches, wiring must be installed underneath piping. “The Irrigation Association’s [Certified Irrigation Contractor] program harps strongly on this,” Fry says. “The wiring must be underneath the piping, as you would with your control wires for irrigation. This protects the integrity of the wiring system.”
Look out for wet locations
Another subtle difference between irrigation and outdoor lighting installations involves the space around wet areas, such as pools and hot tubs. NEC Article 680.1 includes strict guidelines on the voltage requirements for these spots.
“In or around a pool or wet location, all lighting wire has to be in conduit in a nonmetallic sleeve or raceway,” Fry says. “The fixtures and wires should be UL 1838 with IP (ingress protection) ratings between 66 and 68.”
In addition, Fry says that receptacles or power sources located in damp or wet areas must be Class A weather-resistant ground fault circuit interrupters and must have “while in use” cover.
Steven Christal, an account manager with Center Cut Landscaping in Las Vegas, says that choosing the correct materials is the only way to prevent maintenance concerns in the future. “Definitely use waterproof splice kits and waterproof wire nuts,” Christal says. “Make sure everything is waterproof as much as possible to avoid corrosion.”
Going through walls
Any time wiring for irrigation or outdoor lighting goes through the wall of a garage, shed, barn or other structure, the wire needs to be in conduit. Fry says that, under sidewalks and through landscapes, both irrigation and lighting wire can typically be in the same sleeve. However, once the pathway reaches a wall, the wires need to be separated into their own sleeves.
“When it comes to going into the house or through a garage or shed, never ever put irrigation wire or lighting wire together with your 120-watt line voltage,” Fry says. “Everything needs to be separated and in conduit. You’re going to two separate controllers once inside and through the wall, so do not combine them in the same conduit.”
When it comes to equipment, Fry says that both irrigation and lighting contractors should be using a waterproof connection with a good UL rating and the same equipment, adding weight to the case for combining both irrigation and lighting installations into one project.
Lighting-specific tips and tricks
While the equipment is the same between industries, there are a few tips and tricks that irrigation contractors should keep in mind when it comes to wiring for lighting.
“On the lighting side, it is a good idea to put S loops in transition areas,” Fry says. “If you’re going from a buried wire into a conduit or into a sleeve, put an S loop in your outdoor lighting wire to allow for expansion due to thawing and freezing. Or, you could be in a high construction traffic area, and they may accidentally slash your wire. This allows you to have some flexibility.”
“Think about the people after you who are maintaining it, and do things right the first time.”
— Steven Christal, account manager, Center Cut Landscaping
While valve installations typically include some slack wire in the valve box for repairs and surge protection, Christal says that leaving some extra wire during lighting installation is always a wise idea, as it allows contractors to relocate light fixtures if necessary.
“With lighting, you don’t know until nighttime if it is exactly where you want that light to be, so give yourself room to play with it,” Christal says. “I’ve seen homes with wire so tight I had to splice a new wire to move the fixture a couple feet forward or backward.”
Christal also encourages irrigation contractors to plan ahead by leaving room for growth on transformers. He says the 80/20 rule applies, and he discourages contractors from using more than 80% of a transformer’s capacity.
“Unlike irrigation, you should leave room to future-proof your jobs. If you have a 100-watt job, use a 200-watt transformer,” Christal says. “Think about the people after you who are maintaining it, and do things right the first time. It’s a courtesy thing that all contractors should be mindful of.”
Fry also says that keeping wire around the foundation of a home or building, along stairwells, underneath stairways, along the edge of patios and out of planting areas, as well as a minimum of 6 inches underground, will help reduce callbacks for damages.
“With a 6-inch minimum, if you aerate, you’re going to get a callback to do a repair,” Fry says. “It just makes sense that while the irrigation trench is open, drop your wire in with the pipe to reduce the risk of damage.”
“When it comes to going into the house or through a garage or shed, never ever put irrigation wire or lighting wire together with your 120-watt line voltage.”
— Chris Fry, CIC, CIT, CLVLT, owner, Irrigation & Lighting Specialties
While irrigation and lighting adhere to the same codes and many of the skills are transferable across industries, there is no argument from irrigation professionals that lighting design is an art.
“If you are new to lighting, learn the artistry of lighting,” Fry says. “It is more than just running wire and mounting a transformer. When it comes to fixture placement, that’s the artistic end of it, and that’s where the architect, designer, homeowner or somebody else may want to get involved.”
Fry says that joining an association that teaches lighting design is one good way to enhance knowledge of lighting placement, color temperature and other design principles.
While even those experienced in lighting design learn new tricks as they progress within the profession, Christal says distributors and manufacturers are also a good source of information.
“Every gauge wire will come with information on how long of a run you can do, just like with irrigation wire,” he says. “The information is out there — it’s knowing where to look for it and how to use it.”
Learn the rules governing the trade
While irrigation and lighting can go hand in hand, novices should make sure to familiarize themselves with the NEC. It’s also important to understand the rules and regulations governing the specific state, county and municipality where work is being done.
“Some states have licensing to put in low voltage called an electrical specialty license,” Fry says. “Before you venture out, make sure you’re aware of your code enforcement laws, municipality laws, jurisdiction laws. Florida requires it; South Carolina does not. Some counties in Georgia require it; some do not. Just make sure you’re adhering to the requirements.”
