The installation of a pole top protection device allows older, in-service pole tops to exhibit “like new” characteristics even though the pole may be decades old. Without protection, pole tops are highly vulnerable to premature aging. High moisture content also encourages freezing and splitting of the pole top. Pole top protection also significantly reduces moisture - a necessity for decay - limiting attack from wood-destroying fungi. These protective “roofs” are designed to prevent UV degradation of both the preservative and exposed wood fibers. Installing pole top protection devices extends wood pole service life by providing a “roof” for the vulnerable, exposed pole top. If the pole top cannot be repaired, there are additional costs for pole replacement. When a utility must deal with these problems on an unplanned basis, valuable crew hours are invested in repairs and, in many cases, revenue is lost. ![]() Loose insulators and floating conductors can lead to outages and increased safety risks for the public and utility personnel. These conditions eventually lead to problems with the integrity of the connection between the pole and the hardware it supports. Because decay starts internally, it can go undetected until it has weakened the structure beyond repair.ĭecayed pole tops can lead to split or weakened tops. Once these conditions are present, internal decay can advance rapidly in the pole top area. The constant exposure to wet-dry and hot-cold weathering cycles will negatively impact the longevity of the pole top if not protected.Īs the preservative protection provided the pole top by the original treatment is weakened, cracks and checks develop near the pole top surface, exposing untreated heartwood or inner sapwood to moisture and wood-destroying fungi. Additionally, the tops of poles originally treated with pentachlorophenol or creosote are challenged most from preservative depletion via the force of gravity over time. It degrades both the wood and the original wood preservative, causing the wood to become weaker and more likely to be eroded by weathering. UV sunlight is probably the most obvious abiotic agent damaging pole tops. Abiotic deterioration can be caused by ultraviolet (UV) light, water, mechanical activities, chemicals, and temperature. Wood poles are susceptible to degradation by a variety of agents, both abiotic (non-living) and biotic (living). Knowledge of wood as a material may lead pole owners to implement preventative measures that help retain pole strength, maintain pole condition, increase reliability, and reduce avoidable repair and replacement costs. ![]() ![]() ![]() Utility pole owners would be well-served through a greater understanding of the deterioration modes for wood poles. Utility standards engineers and procurement personnel typically require their poles be manufactured according to American National Standards Institute (ANSI) and American Wood Protection Association (AWPA) guidelines to ensure the desired size, strength, material quality, original treatment loadings, and decay resistance properties are present. Wood poles are also a renewable resource. After many decades of use, the wood pole remains a preferred material because of its durability, strength, availability in multiple lengths and classes, and low acquisition and life cycle costs. Wood utility poles numbering approximately 150 million support the delivery of high-voltage electric transmission and distribution service throughout North America.
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