Wildfires burned more than 2.5 million acres of land in California in 2021 and, with high heat and record drought in the forecast, the state could be facing similar losses in 2022. To reduce fire risk and improve the resiliency of electrical grids, California’s utility companies are beefing up their mitigation efforts, trimming trees, burying electrical lines and, in some cases, replacing wood electrical poles with fire-retardant FRP poles.
Composites manufacturing companies have been selling FRP utility poles in various parts of the U.S. for almost a quarter century, and now utilities in fire-prone areas have an even greater incentive to use them. Creative Pultrusions, part of the Creative Composites Group (CCG), has developed an FRP pole with a highly fire-retardant composite sleeve that protects the base pole and improves its ability to withstand the fierce wildfire temperatures.
“Our poles have always been fire-resistant. They meet the UL 94 V-O classification, which means they will self-extinguish on a vertical burn,” explains Dustin Troutman, CCG’s director of marketing and product development.
Over the years, the company has continued to research combinations of thermoset resins and fire-resistant additives to improve composite poles’ fire resistance. In early 2020, the company introduced its new line of FireStrong™ poles, which feature the FRP sleeve. The FireStrong composite material has been engineered to withstand three minutes of temperatures at 2100 degrees Fahrenheit – the conditions that can be created by the brush, grass and chaparral shrub fires that are typical in California and other Western states.
The composite sleeve is unique because it not only insulates and cools the pole, but also protects it. The heat from a fire triggers an endothermic chemical reaction in the sleeve which produces water that absorbs thermal energy and insulates the pole. The outer sleeve protects the FireStrong pole from reaching temperatures that would cause permanent strength loss.
At the request of a utility company customer, CCG added a temperature measurement device into the pole to get an accurate read on what happens to it during a fire.
“The utility company wanted a way to inspect the poles post-fire to determine what kind of strength retention they had,” says Troutman. “So, we incorporated a permanent measuring device that continuously monitors the temperature of the surface of the FRP pole and records the maximum temperature it reaches. Based on that temperature exposure, the utility can determine whether to replace the pole or continue to use it because they know the strength is fine.” A utility can check the recorder, positioned on the pole approximately two feet above the ground line, by removing an access cover.
CCG also provides utility companies with a visual standard they can use to determine a pole’s strength after a fire. “Because we’ve tested so many poles, we can look at a pole and gauge, based on the amount of char and how high the char is on the pole, whether it was compromised or not,” explains Troutman.
Using these two indicators, the utilities can replace only those poles that don’t have the necessary structural integrity to carry the wires. That saves them money and labor. If utilities want to continue using a pole, they can repair the insulating sleeve so it’s ready for the next fire event.
CCG manufactures FireStrong poles in a pultrusion process using proprietary, high-end engineered fabrics. It incorporates UV inhibitors in the materials and then uses its in-mold coating technology to add an extra layer of UV protection during the manufacturing process.
The composite sleeve, which is installed during the manufacturing process, is available in different lengths. Utility companies determine what size sleeve they need based on factors such as the height of the pole, the height of the fuel source and the potential height of the fire considering the slope of the area where it is installed. FireStrong poles are delivered to customers pre-drilled and ready for installation.
To validate the performance of FireStrong poles, Southwest Research and the Western Fire Center conducted test burns. “After the poles were burned at a certain temperature for a certain amount of time, we took them to EDM International, which used its testing tools to determine the strength retention of those poles post-fire,” says Troutman.
In addition to their fire-resistance, FireStrong poles offer all the other advantages of FRP utility poles. They have high dielectric strength, which means they are poor conductors of electricity. That reduces workers’ risk of electric shock from shorting wires. Unlike wooden poles, they don’t leach any preservatives or insecticides into the ground and contaminate water sources. They are lighter weight than equivalent-size wooden poles, so they are easier to transport into inaccessible areas. Although they are more expensive up front, they have an expected lifespan of 75 years and can withstand hurricane-strength winds that knock down wooden poles.
Troutman says that one California utility has begun installing FireStrong poles as part of its fire mitigation efforts. Although there have been no fires in these areas, Troutman says the utility is confident that it is now prepared for them.
Troutman also envisions other applications for CCG’s fire-retardant technology.
“I think the logical thing is for us to take this patented technology and expand it into applications where fire performance is critical – bridges, grid structures or anywhere where fire would be a concern,” he says.
Mary Lou Jay is a freelance writer based in Timonium, Md. Email comments to firstname.lastname@example.org.