Penta poles are utility poles that are made from pressure treated wood that is infused with pentachlorophenol, otherwise known simply as penta. Penta is a pesticide that protects the wooden utility poles against insects and fungi that would otherwise destroy the wood. Penta poles account for nearly 50 percent of the utility pole market in North America, making them some of the most common utility poles in the country.
Penta has been produced commercially since 1936. It has maintained its popularity as a wood treatment thanks to its effectiveness as a preservative. It protects the poles from nearly every type of wood-destroying fungus as well as termites and powder post beetles, among other troublesome insects. It has also been shown that wood treated with penta can last eight to twenty times longer than its normal service expectancy. Penta poles also have a light honey brown color after they’ve been treated, giving them a certain aesthetic appeal.
How Pental Poles Are Made
Penta is carried into the wooden poles through a petroleum oil solution. When it is properly applied, penta will remain in a treated wooden utility pole for several years. It does degrade over time when it is present in lower concentrations, especially when it is exposed to sunlight and certain types of bacteria. This is why the surface of penta poles may start to show their age over time while the preservative continues to do its job under the surface.
In more recent years, biodiesel has been used to carry penta into wooden poles instead of petroleum oil. Not only does this all but eliminate the petroleum smell that has accompanied freshly treated penta poles for years, but it is a more sustainable alternative. Biodiesel is derived from renewable sources such as corn and soy, while petroleum is an increasingly limited resource.
Penta poles still make up a large percentage of utility poles in use in the United States, and they will almost certainly not be going anywhere anytime soon. Now that many penta poles are made from more renewable resources, they are also more environmentally-friendly than the wooden utility poles that have been made for the last several decades.