Pole Top Protection Extends Wood Pole Service Life

Wood poles are susceptible to degradation by a variety of sources. Deterioration can be caused by ultraviolet (UV) light, water, mechanical activities, chemicals, or temperature. UV sunlight degrades both the wood and preservative causing the wood to become weaker and more likely to erode by weathering. Additionally, the pole top suffers from preservative depletion via gravity and constant exposure to wet-dry and hot-cold weathering cycles.

As the protection of the original treatment in the pole top is weakened, cracks and checks develop near the pole top surface, exposing untreated heartwood or inner sapwood to wood-destroying fungi. With these conditions present, decay can advance rapidly in the pole top.

Installing pole top protection devices extends wood pole service life by providing a "roof" for the exposed pole top. These protective "roofs" are designed to prevent UV degradation of both the preservative and exposed wood fiber. Pole top protection significantly reduces moisture - a necessity for decay and a cause of freezing and splitting. Without protection, pole tops are vulnerable to premature aging. Installation of a pole top device allows older, in-service pole tops to exhibit "like new" characteristics even though the pole may be decades old. Pole top protection devices help ensure that it is NOT the pole top limiting life expectancy of wood poles.

Evidence this strategy works has been validated through an ongoing study by the Oregon State University - Utility Pole Research Cooperative (page 83). This study demonstrates that installing pole caps quickly reduces the moisture content of pole tops to help prevent the conditions needed for decay. The Rural Utilities Service (RUS) accepts a pole top protection device for use on new pole construction.

Many utilities include the cost of pole top protection in capital budgets for materials on new pole installations, creating future savings for O&M and capital accounts. This small investment at the outset can save thousands of dollars in the future.

Over an extended number of years of service life, how many pole replacements can be avoided by managing the aging of pole tops? How many poles that otherwise may have been candidates for pole restoration will have to be replaced because of avoidable pole top decay? How many outage risks related to pole top integrity can be eliminated?

To learn more about pole top protection, please visit the pole top protection page of our website or contact our Osmose products team at [email protected].