They are called telephone, telegraph, power, utility or transmission poles, and they form the national grid system that gives everyone streetlights, electrical power and utility services like television programming. Placing the poles overhead keeps them out of the way of community traffic and protects utility services from being disrupted by storms or inclement weather. Although some utility posts can be created using metal, concrete or fiberglass, the most common material occurrence is wood poles.
Most Popular Wood Types
Southern yellow pine is used most often to make utility poles. The type of tree harvested to secure yellow pine will always depend on which region of the United States the tree originates. In the South, the name is used to mean the Loblolly, longleaf, shortleaf or slash pine. Because these trees grow in acidic red clay, they are denser and used in home construction and telegraph poles. The Jeffrey or ponderosa pine comes from the western region of the nation.
Other types of trees harvested for utility pole wood include the western red cedar, jack pine, Douglas fir, Pacific silver fir and lodgepole pine.
Size of the Wood
Once trees are cut and designated for utility poles, they must be treated to make sure they can have an extended life to help maintain the electric grid they will support. Depending on where the poles will stand and what they will hold, they are typically 40 feet long with approximately 6 feet of the pole buried in the ground and spaced about 125 to 300 feet apart. There are circumstances, though, that can require the poles to be as much as 120 feet tall.
Treating the Wood
Wood manufacturing facilities process the wood with a quality preservative applied through pressure treating. First, they use a commercial vacuum to open up cells in the wood and create receptacles for the preservative chemicals. Each type of wood and each wood species has a pre-determined amount of stress it can handle during forced preservative treatment. After this process, the wood is not ready to withstand the wear and tear of the elements.
Fortunately, the wood treating process is a made-to-order one. Processing facilities store the wood in warehouses so that a utility pole can be placed when it is needed. The poles are branded, meaning they are carved or etched by burning with information to tell the buyer the manufacturer, height, strength species, type of preservative and the year or date of manufacture. This “birth mark” means they are ready for municipalities to order.