Ground Line Decay In Wooden Utility Poles

In several previous articles, we have talked about the effects of leaching, decay and rot at the ground line, and 6″ or so below it. At this level, wood preservatives lose effectiveness over time.  Factors arising from climatic changes such as oxidation and the constant wetting and drying of the ground line pole section lead to leaching and the loss of preservatives. These factors lead to a reduction in the concentration of the biocides and water repellence for water repellent wood preservatives. Once this occurs, the pole becomes vulnerable to attack by wood-decaying organisms and termites. 

There are an estimated 30,000 different types of wood-destroying fungi. These fungi break-down all kinds of organic matter, and over millions of years have become a highly efficient waste disposal system, so much so that they are the primary cause of wood decay. A combination of water, fungi, organisms, nutrients, and warm oxygenated soil near the ground line gives rise to a perfect environment for wood decay. Depending on geographical location, this could also lead to a more appealing target for the tiny yet very deadly termite! 

Ground Line Barrier Options

Because the most vulnerable section of a wooden utility pole lies at and just below the ground line, we can protect this area with a barrier product. Barrier products work in conjunction with the preservative treatment to increase the service life of the pole by eliminating or reducing the factors necessary for wood decay to occur whilst reducing or preventing loss of wood preservative. These products can inhibit moisture ingress, reducing the likelihood of leaching and increasing the life span of both the wood preservative and the pole itself. Furthermore, a lack of decaying wood and a sealed outer skin is an excellent termite deterrent. Barrier products fall into two categories; partial barriers and full barriers.

Partial Barriers

Partial barrier systems are available in several forms, including a simple ground line wrap, self-adhesive tape, and heat shrink tube. Other products include a wrap or heat shrink sleeve with a metal foil behind the outer wrap or a complete pull-on “bag” type product that covers the whole in-ground section of the pole. The issue with this type of product lies in the name – “partial”. As we have previously discussed the ingress of moisture, leeching, and fungi to the pole can allow decay and pole failure to occur. If a utility pole is only partially sealed at the ground line the potential for decay still exists. The main issue with these products is that all causes of decay can still access the pole behind the barrier, and water may track to the top of the sleeve/barrier creating a wet or damp band at the top of the sleeve where decay can then occur. Suppose the surface of the pole at the critical groundline does not have a complete seal. In that case, it is susceptible to all possibilities for rot and potential loss of preservative protection over time within the protected zone due to moisture movement behind the outer sleeve. 

Total Barrier Protection

For barrier products to have a total seal and provide complete protection, the product must exclude all air and moisture from the ground line section of the pole. The image below shows the total barrier sleeve system in contrast to the above picture of a partial barrier sleeve. With a complete barrier system, the pole surface is fully sealed behind the outer sleeve excluding moisture, organisms and nutrients preventing the possibility for decay, giving significantly improved pole lifespan. The sealed barrier lowers the entry point for water, in turn reducing moisture in the upper part of the sleeve. The section of the pole above the sleeve experiences drying by the air keeping the moisture content below the 25% needed for decay. By working in conjunction with the wood preservative, the total barrier system prevents loss of wood preservative from wetting and drying, ensuring preservative protection within the sleeved zone over time. 

The Polesaver Sleeve

Polesaver sleeves comprise of high performance, long-lasting, dual-layer barrier technology that fully seals the wood surface behind the outer sleeve creating a total barrier to all the causes of decay. The sleeve consists of a high-performance UV stabilised outer film lined with a thermoplastic meltable sealant. Upon heating (see application method for further details), the thermoplastic sealant liner melts, and the outer sleeve shrinks down tightly onto the pole to create a robust, air and watertight seal to the pole surface excluding all of the factors necessary for decay to occur. The seal also prevents the loss of preservative treatment protection within the sleeved zone. Polesaver makes conventional ground-line decay impossible. The use of high-quality components backed by long term testing means that Polesaver sleeves are guaranteed to maintain a barrier to all the causes of decay for 50 years.

Polesaver Sleeve Features

Our full barrier sleeves have a range of innovative features. They are compatible with all forms of in-service pole decay testing, including hammer testing, spike or probe, resistograph and sound wave-based systems without affecting the results. A high-performance sealing tape to re-seal holes resulting from testing penetration is available. The tape will continue to protect the utility pole by reinforcing the high-quality seal of a Polesaver sleeve. 

Polesaver sleeves include radio-frequency identification (RFID) tags with a unique electronic serial number. Using readily available reader technology such as a phone or PDA app, the serial number can allow quick and easy implementation of full asset management. A management tracking system can display instant data about pole location, installation date, pole supplier and the unique pole serial number as well as associated information on cables and pole-mounted switchgear etc. As well as being able to offer a range of software, we can also provide retro-fit tags to allow full asset management of other assets such as switchgear, transformers etc. 

Polesaver sleeves are a tough and durable product; however, in some instances, the utility poles may be subject to a variety of extreme transport logistics and installation methods. During these periods damage might occur to a pre-applied sleeve. To combat this, we can supply Polesaver Plus. This additional durable wrap remains on the pole for the duration of the pole’s life and is low in cost and quick and easy to apply to the pole. 

Total Barrier Benefits

There are significant benefits to using a total barrier protection system such as Polesaver, the greatest being a significantly longer pole life with a calculated life extension factor of at least x 2.5 based on long term independent field testing. Polesaver barrier sleeves also prevent the decay that leads to loss of strength over time, significantly improving both safeties when poles are climbed and greatly reducing the likelihood of pole failure in bad weather conditions.  

With regards to maintenance, total barrier protection systems potentially allow for an increase in pole inspection intervals; therefore, a reduction in the percentage of poles inspected, potentially giving significant cost savings.

In some countries, costly pole remediation is a standard practice typically after 20 years or so in service. In North America, this practice is widespread, especially where numerous utilities share the same pole, making pole replacement more difficult. Replacement is time-consuming, and the costly process involves digging out around the ground line and re-treating the pole with toxic treatments or where decay is more advanced, the use of steel reinforcing or hand-applied glass fibre reinforcement. By preventing the onset of decay the use of total barrier sleeves can eliminate the requirement for this costly exercise giving significant costs savings

In Conclusion

Several barrier products exist in today’s market; however, none are as versatile or cost-effective as Polesaver, the future of total barrier protection. Our sleeves make ground line decay impossible. In the next blog, we will be looking in detail at the test data for total barrier sleeves and comparing this with the results for alternative methods of partial protection.

Alternative Utility Pole Options

In this article, we’ll be looking at alternative utility pole options and giving an overview of their effects on safety, maintenance and overall environmental impact. We will also take a look at alternative readily available solutions used to increase the life of standard treated wooden power and telecom poles. 

The following information is from a report published by AquAeTer, Inc regarding an environmental lifecycle assessment of wooden, steel, concrete and composite poles (Full report available on request). The products used in the report represent general product categories, which are subject to different designs and material contents. Three of the most commonly used alternatives to wooden poles are steel, steel-reinforced concrete and composite/plastic. The composite poles use a fibreglass construction, sometimes featuring an outer plastic coating. From an initial cost standpoint, all of the above options, as a general rule, incur a more significant initial purchase cost, with composite being particularly expensive due to its resource requirement for production. 

Failure Modes and Lifespan 

While we might assume that these more costly alternatives provide longer life, they are subject to many of the same issues of failure as wooden poles. Although traditional leaching and decay that we see in wooden poles are not present, both concrete and steel poles suffer from ground line corrosion this effect being made worse where poles are installed in acidic soil conditions.  The lifespan of composite poles used in ground contact is currently an unknown with osmosis being a potential issue where conventional polyester resin systems are used. Osmosis significantly weakens composites over time. More costly epoxy resin systems offer much greater resistance to osmosis as do plastic encapsulated composites.

Anecdotal evidence indicates that concrete and steel poles typically have a service life of around 40 years.  Use in acidic ground conditions combined with imperfections in the quality of galvanising can lead to failure of galvanised steel poles in a significantly shorter time period. 

Impact on Installation and Maintenance? 

Concrete poles are heavy and more challenging to handle than traditional wooden poles. The companies we work with who have used concrete poles tell us that the significantly greater weight of these poles brings new requirements in terms of transportation and lifting equipment plus new challenges in conducting a safe and efficient installation process. As a result, the cost of the pole and the installation cost increase significantly, also, it is worth noting that these poles cannot be easily climbed. The conductivity of steel reinforcement inside the pole is also a significant issue for many power distribution companies. 

Environmental Impact 

The use of alternative pole materials can also have a significant environmental impact, especially when it comes to CO2 emissions from pole manufacture. The majority of utilities have CO2 reduction targets as part of their commitment to corporate and social responsibility. The use of alternative pole materials can have a significant impact on meeting these targets. Whilst wooden poles typically capture and store around 320kg of CO2 from the atmosphere, the manufacturing of poles from alternative materials generates significant amounts of CO2.

For instance, for a typical utility that replaces 30 thousand poles a year, a switch from wooden poles to galvanised steel poles will see CO2 emissions increase by 33,000 tonnes a year. Whilst switching to concrete leads to an increase in emissions of 53,000 tonnes, the use of composites increases emissions by 35,000 tonnes a year*.

*Source “Conclusions and summary report of an environmental life cycle assessment of utility poles” Prepared by AquAeTer Inc.

Increasing Wood Utility Pole Life By +20 Years

In the first of this series of blogs we covered the causes of wooden pole failure and the methods of preventing this in detail. To summarise, wooden utility poles typically fail as a result of decay at the critical ground-line section of the pole due to the effectiveness of wood preservative diminishing over time due to oxidation and leaching. This leaves the pole vulnerable to decay, loss of strength and failure.

Decay starts at the mechanically highly stressed pole section in the upper 200mm (8″) of the ground where conditions are ideal for decay. This is because of high moisture content, oxygen and higher temperatures creating the perfect environment for decay to occur. Deeper in the ground and above ground, the conditions for decay are not generally present, and failure at these points is highly unlikely. The use of additional protection at the vulnerable ground line section of the pole provides a highly effective and proven means of overcoming the traditional weakness of wooden poles; ground line decay. In the next section, we will look at the options for achieving this.

Barrier Protection – Partial Barriers

Barrier products provide additional protection to a wooden pole at the vulnerable ground line section of the pole and work in conjunction with the wood preservative to increase pole service life. Barrier systems come in two types; partial and full barriers. Partial barriers are available in many forms such as a simple ground-line wrap, self-adhesive tape, heat shrink tube, wrap with a metal foil behind the outer wrap or a complete pull-on “bag” that covers the whole in-ground section of the pole. Partial barrier systems have one thing in common – they do not seal the surface of the pole behind the sleeve or bag. This means that preservative can be lost from the wood behind the barrier, and water can access the entire pole surface behind the outer barrier. Capilliary action between the outer sleeve and the wood “transports” moisture from the ground to the top of the sleeve. This creates a damp or wet band at the top of the bag or sleeve, allowing decay to occur at the top of the barrier or behind the barrier itself. Without entirely excluding moisture, oxygen, organisms and nutrients, there is still potential for decay to occur. 

Total Barrier – Total Protection From Decay

Total barrier systems have a meltable sealant behind the outer barrier. The sleeve is heat applied causing the inner liner to melt and seal the pole surface, forming an air and watertight seal. This excludes all of the factors necessary for decay to occur, including oxygen and moisture. This seal ensures that the wood at the top of the sleeve remains below the 25% threshold at which decay can start whilst also preventing any loss of wood preservative from the protected zone. Total barrier sleeves such as Polesaver make conventional ground line decay impossible.

Graph showing projected loss of pole bending moment strength over time for standard preservative-treated wooden pole and preservative treated pole protected with a Polesaver total barrier sleeve.

Summary

Alternative pole types of concrete, steel and composite may be advantageous in certain respects; however, wooden poles have shown to be more appealing from the viewpoint of cost, installation and environmental impact. Total barrier systems offer a proven and highly effective means of allowing wooden utility poles to match or better the life of alternative pole materials at a significantly lower cost. In the next blog, we will look in detail at partial and full barrier sleeves.

Non-Uniform Decay: Ground Line Decay

Wooden utility poles are exposed to many different conditions along their length, from widely varying weather conditions above ground to cool damp and stable conditions deep in the ground.

It is at the ground line section of the pole where above and below ground conditions meet to create the perfect conditions for wood decay to occur.

Know Your Enemy

The topsoil in the upper 6″ or so of the ground have evolved over millions of years to become a highly efficient waste disposal system. Any dead organic matter such as wood, leaves etc. that falls on the ground breaks down and is broken down by a multitude of organisms in the soil. 

Fungi are very successful inhabitants of soil; they break down all kinds of organic matter, decomposing soil components. Fungi convert dead organic matter into biomass, carbon dioxide, and organic acids. There are hundreds of thousands of different types of fungi of which around 30,000 are known to attack and destroy wood. Fungal attack is the primary cause of decay and failure in wooden utility poles.

Wood destroying fungi thrive when the environment is ideal with damp, warm soil and a good supply of oxygen being essential requirements. These conditions tend to occur in the upper 150mm (6″) of the ground where rainfall, heat from the sun and a good air/oxygen supply are all present. 

At greater depths, the soil tends to be more compacted, limiting the flow of air and oxygen. At the same time, the heating effect of the sun falls away, leading to lower temperatures and significantly reduced fungal activity. 

Termites – Small But Deadly

In many parts of the world, subterranean termites pose a significant threat to wooden utility poles. There are two things to bear in mind when looking at termite attack of poles. Firstly, termites don’t like eating preservative-treated wood. Secondly, as a general rule, independent research shows that many termites find it easier to digest wood that is subject to fungal decay. The graph below shows the result of large-scale testing in Australia where there is a clear relationship between the incidence of pole decay and termite attack with termite attack following shortly after the onset of wood decay. The ground line or top of the pole being the usual entry point for the termites. From this, it is clear that maintaining preservative concentrations in the wood and preventing decay is critical in reducing the likelihood of termite attack, especially at the vulnerable ground line section and to a lesser extent at the pole top.

Dry Wood Does Not Rot

The incidence of wood decay is directly related to the moisture content of the wood. For wood decay to start a moisture content of 25% or higher is required. If the moisture content is higher, then the rate of decay generally increases up to a point all else being equal. Once wood decay starts then it can continue at a lower moisture content of 20%, below this level wood decay does not occur.

A wooden pole buried in the ground behaves like the wick of a candle, it absorbs water from the soil with the difference in vapour pressure causing the water to move up the pole where it is lost to the air by airflow and warmth from the sun. This moisture movement is a slow but continual process with rainfall and heat from the sun being the main drivers in this process.

In practice, this generally means that the entire ground line section of the pole and the inner core of the pole section up to around 50cm or 20″ above ground will have a high moisture content greater than 25%.

You may think the section above ground will not decay as it is not in contact with fungi in the soil. Unfortunately, this is not the case; cracks in the pole form over time through to the damp core of the pole. Airborne microscopic fungal spores can be blown into the cracks and come into contact with the damp wood in the centre of the pole just above ground level. The spores can then germinate and destroy the inner core of the pole; this is called core rot. 

Partial Protection – Wood Preservatives 

Partial protection with liquid wood preservative applied to the pole under vacuum/pressure cycle has been the traditional method of delaying the onset of wood decay and pole failure. To be effective the preservative treatment process has to be carefully controlled to ensure correct preservative concentration (%), retention (kg/m³or PCF) level and depth of penetration (mm or inches). For best results, the pole is dried to an optimum moisture content before preservative treatment. Modern drying methods and the use of automated pressure treatment plants give consistent, high-quality protection from decay when correctly used.

The wood preservative treatment provides excellent protection above ground and deeper in the ground where conditions for decay are less than ideal. It is at the mechanically critical ground line section of the pole where wood decay and failure are an issue.

At this point exposure to higher temperatures, oxygen and moisture can accelerate the oxidation of the wood preservative. At the same time, weather changes cause regular wetting and drying cycles leading to the gradual migration of wood preservative from the pole into the soil. The overall impact is a loss of toxicity to fungal organisms over time.

Wood preservatives come in 2 types:

•   Water repellent preservatives such as Creosote, copper in oil and Pentachlorophenol
•   Non water repellent wood preservatives

Water repellent products combine biocides along with natural water repellent characteristics in the case of Creosote or the addition of oils such as AWPA P9a oil to create water repellence when used in combination with biocides such as Pentachlorophenol or copper. The oils are not “fixed” to the wood and on their own provide limited  life extension as they are not biocides. They extend life by creating a partial barrier to moisture ingress from the ground*. 

Over longer period of time the oil/preservatives are lost as a result of migration to the soil. This effect is most pronounced at the ground line section of the pole where climatic wetting and drying cycles combined with ideal conditions for oxidation can exacerbate this loss of effectiveness over time. 

There is a European review of the licence for the continued use of creosote as a wood presevative  in March 2021. With France having recently banned the use of creosote and the European Chemicals agency (ECHA) having recently classified creosote as a carcinogen, only 6 European countries now using creosote in volume it is looking increasingly unlikey that the licence for the use of creosote will be renewed. 

Non water repellent water borne copper salt wood preservatives have been widely used across Europe as a more environmentally acceptable alternative to Creosote since 2005

These wood preservatives have a chequered history with reports of early pole failures but the use of additional co biocides to address the issue of copper tolerant fungi and use of fixatives, along with improved treatment standards and higher retention levels have increased pole life for newer versions of this preservative. Many of the utility customers we talk to who have used these preservatives since 2005 tell us that they expect a 15 to 20 year pole lifespan with the latest versions though longer life may be achieved in reality.

For all utilities there is a relentless focus in on cost reduction, improving safety and network reliabilty. Even with a creosote treated with 40 year pole life for most utilities wooden pole replacement  is one of their single largest operating costs. In the Northern hemisphere it typically costs around  €/$/£ 2500 to replace a power distribution pole and this soon adds up with a typical cost of around €/$/£25 million per 10,000 poles replaced per year.

To try and address the rising pole replacement cost issue in Europe and match the service life given by creosote, preservative manufacturers have recently launched new products that use a combination of copper-based wood preservatives and water repellent oil. This combination should undoubtedly give a longer pole life than water based copper preservative alone but how much longer is currently unknown. It is this unknown that is a concern for many utilities we speak with especiaily those who have experienced issues with pole failure in the past. Factor in feedback indicating significantly higher costs for this treatment and many of the utilities we speak to are now  reviewing the options open to them including the use of alternative pole materials such as steel, composite or concrete along with partial and Total barrier systems.

An example of this is the recent decison by France Telecom (Orange)  to use galvanised steel poles  instead of treated wooden poles in France, in spite of this increasing their CO2 emmisions by around 220,000 tonnes a year. This is bad for the environment and a major blow to the wooden pole producers, forestry sector and preservative manufacturers with lost sales of around 220,000 poles a year. 

* Full reports available on request

What Does Pole Failure Cost?

The costs to a utility to install and maintain wooden utility poles is often one of their single highest expenditures. Using annualised combined costing that includes installed cost and inspection and remediation costs spread over the poles expected life gives a clear and easy to use figure for pole cost, and comparison against alternatives. 

Let’s take a 1000 mile North American LV distribution network as an example; our research based on industry data shows:

–  with an average pole spacing of 250ft equating to 21,120 poles, the combined costs of each pole and the cost of installation totals $63 million. 

– Based on the assumption that 12% of these poles are inspected every ten years at an inspection cost of $100, annual pole maintenance cost would be $633,000 including remediation work.

– Based on a 20-year lifespan for a water-based copper preservative (Creosote/CCA 40 years), the total lifetime maintenance cost for 21,120 poles would be $25 million.  

– In total, the lifetime cost of 21,120 poles, based on our industry research data, is $88 million. 

Our data shows that the maintenance costs to Utilities are substantial. Although this example is specific to North America, our research has expressed similar results across a range of geographical locations.   

In conjunction with the apparent costs, several potential hidden costs can occur as a result of pole failure. Depending on market regulation, grid failure as a result of pole collapse may incur financial penalties for Utilities. Pole collapse not only has the potential to cause grid failure, but it also presents a possibility for compromising the safety of employees and the public. The likelihood of these failures and the resulting costs can both be reduced; if you would like to know how much you could save with polesaver try our cost calculator for more information. 

These unwanted costs, both explicit and hidden, are a significant target for potential reduction.  Look out for our next article as we explore the available alternatives for prolonging pole life, including alternative pole materials and partial and full barrier systems and their effects on maintenance, safety and the environment.

Introduction 

Termite attack of wooden utility poles can be a severe problem when the right conditions exist for termites to thrive. Termites can do a lot of damage to wooden poles very quickly, and this nearly always cause pole failure.

The most effective way of inhibiting attack is by using multiple methods of prevention together, including chemical treatments and barriers. While it is not possible to remove all chances of attack, it is possible to reduce the likelihood of an attack significantly. This report looks at the conditions required for an attack to occur, evaluates the current methods used to prevent an attack and the benefits offered by full barrier sleeves as a means of reducing the likelihood of termite attack occurring.

Why Do Termites Attack Wooden Utility Poles?

Wood is a food source for termites, and where the right conditions exist, termites can consume large parts of a utility pole and weaken it in a relatively short period of time.

It is well known that termites are attracted to and have a much higher tendency to attack decaying wood in ground contact. “Fungus infected wood is highly susceptible to termite attack when compared to sound wood” Ref Matsuo, H. and K. Nishimoto. 1973. This attraction is because wood-decaying fungi break down the wood making it more digestible for termites, thus increasing the nutritional value of the wood for the termites.

Independent research shows that “Representatives of all the classes of fungi are associated with termites. Slight deterioration of wood by certain Basidiomycetes of the brown-rot type also increases its nutritional value to termites (Light and Weesner, 1947; Becker, 1948, 1965).

The correlation between the occurrence of wood decay in utility poles and attack by termites is also confirmed by independent research in Australia. (source: Pole Service Life – An Analysis of Country Energy Data, Nathan Spencer Koppers Wood Products Pty. Ltd., Sydney, Australia, Leith Elder Country Energy, Goulburn, Australia).

The graph below is taken from his report below shows a clear correlation between the occurrence of wood decay and termite attack in treated wooden utility poles (C.C.A. treated Eucalyptus poles).

Why Do Termites Target Older Wooden Poles?

As can be seen from the graph above, termite attack rates increase over the life of the pole in almost direct relation to the incidence of wood decay in the pole.

To protect utility poles from fungal decay, many utility companies will use a wood preservative treatment process. Wood preservatives provide a high degree of protection (toxic and repellent effect) to termite attack. It is also well known that creosote and C.C.A. type wood preservatives are very effective at preventing termite attack of a utility pole, however, over time the effectiveness of wood preservative is reduced by leaching, oxidation and loss of water repellence.

This effect is most pronounced at the ground-line section of the pole where exposure to air and frequent wetting and drying cycles occur. Once the effectiveness of the preservative is reduced, the resistance to attack by wood-decaying fungi and termites deteriorates.

This loss of protection over time is variable and depends on climate, ground conditions and other factors, and increases over time. The graph below shows typical loss of pole strength over-time for a pole used in the Northern Hemisphere. (The lifespan and time for onset of decay/loss of strength are generally around half the values shown for poles used in the southern hemisphere.)

Can Polesaver Sleeves Significantly Reduce The Likelihood of Termite Attack? 

Firstly, Full barrier sleeve material has been subject to independent testing using A.W.P.A. E1-97: 2005 (American Wood-Protection Association): 2005.’ The standard method for laboratory evaluation to determine resistance to subterranean termites. In a no-choice and two-choice test, the samples protected with full barrier sleeve material were not attacked by the termites. (Full test report available on request)

Secondly, as has been previously discussed, there is a direct correlation between the onset of pole decay and the likelihood of termite attack of wooden utility poles. Thus, preventing decay at the vulnerable ground line section of the pole where conditions are ideal – meaning that the likelihood of termite attack will reduce significantly.

Full barrier (Polesaver) sleeves applied to the vulnerable ground line section of the pole;

• Prevent leaching and oxidation of the wood preservative, ensuring that the toxicity to termites is maintained over time.
• Full barrier sleeves exclude all the factors necessary for wood decay to occur, making conventional ground-line decay impossible.
• As a result, the use of full barrier sleeves eliminates the likelihood of conventional ground-line decay, thus reducing the associated possibility of termite attack.
• This has been born out of results achieved in the field where Polesaver Rot-Guard™ sleeves have been used to protect poles in areas where termites are present. Independent field testing of poles in service showed sleeves to be highly effective at inhibiting termite attack when compared to unprotected treated poles (test report available on request).

Summary

The likelihood of termites attacking a treated wooden utility pole is closely related to the onset of wood decay, meaning that preventing wood decay in the pole significantly reduces the possibility of termite attack.

Decay in wooden utility poles occurs at the ground-line section of the pole where conditions for decay are ideal. However, full ground-line barrier sleeves like Polesaver make conventional ground-line decay impossible and prevent the loss of toxic/termite repellent wood preservatives. Independent testing also shows that they prevent direct termite attack.

By preventing decay, full barrier (Polesaver) sleeves can significantly reduce the likelihood of termite attack in wooden utility poles.