DOWNLOAD PDF Severe weather reinforces utility’s decision to install fiberglass poles. By Steve Coltharp and Tim Vied, Western Kentucky Rural Electric Cooperative Corp. After losing more than 120 wood poles to Hurricane Ike in September 2008, Western Kentucky Rural Electric Co-operative Corp. (WKRECC) installed seven RS composite utility poles in its system on a trial basis. The composite poles were quickly put to the test when, in January 2009, a once-in-a-hundred-years ice storm rolled through the WKRECC territory. The storm took down more than 1600 wood poles; yet, while the composite poles were on circuits with damaged wood poles, not one composite pole was damaged. It took weeks for WKRECC to fully restore service to its customers. Hurricane Ike Western Kentucky is a serene place with gently rolling hills, meandering streams and rivers, and a lot of trees. WKRECC provides electric power to 38,000 customers living in four Western Kentucky counties. The cooperative’s 100 or so employees do their best to see that 11 substations, 15 miles (24 km) of transmission lines and 4000 miles (6437 km) of distribution lines reliably deliver electric power generated and transmitted by the Tennessee Valley Authority (TVA). This is a predominantly agricultural area of the United States where things change relatively slowly. However, things changed rather abruptly when the region was hit by not one but two major weather events in less than five months. Winston Chambers, a contract engineer with Patterson & Dewar Engineers, assesses damage to a double-circuit joint-use wood pole. First came Hurricane Ike, which surprisingly took an interior course northward over the WKRECC service territory. The hurricane brought sustained winds of 90 mph (145 kmph), toppled thousands of trees and destroyed more than 120 wood poles, knocking out power for weeks. A utility east of the WKRECC service territory had similar issues but not with about a dozen RS composite poles it had installed near Cincinnati, Ohio, U.S. Manufactured by RS Technologies, those poles emerged from the hurricane unscathed. WKRECC took notice. Actually, even before the storm, WKRECC has decided to purchase seven composite poles for a trial deployment. There were several primary reasons for trying out the composite poles: high strength, long life, zero maintenance, environmentally benign materials, light weight, and a modular design that makes installation easy. These benefits helped offset the somewhat-higher initial cost of the composite poles, which were about twice as much as the wood distribution poles they replaced. However, the freight costs for the composite poles were half as much as for wood poles and, according to the contractors who installed them, the composite poles were easier and faster to install, all of which saved money. During the Ike recovery phase in October 2008, the composite poles were installed along a road not too far from WKRECC’s warehouse. The next pole in the line was steel and stood across the road near an intersection. The Ice Storm It did not take WKRECC long to determine the right purchasing decision had been made. On Jan. 27, 2009, a vast swath of the United States was slammed by a brutal winter storm that coated everything with a thick layer of ice. More than 1600 wood poles went down. Many of them snapped like toothpicks under the loads brought about by ice-ladened lines, or by trees and heavy branches falling against the lines. WKRECC lost its entire system, which is fed by TVA, who was down for five days before it was able to restore its transmission. However, it took WKRECC 21 days to completely restore power, and this was only possible because of the mutual assistance help of 500 cooperative volunteers from North Carolina, Alabama, Mississippi, Florida, and Tennessee. An extreme icing load caused this double-circuit double-deadend wood pole to snap. Things got a little crowded at WKRECC’s warehouse at times during this all-hands-on-deck period of reconstruction. In addition to storing supplies, the warehouse complex was also the site for putting up the volunteers and feeding them until all the work was done. Strength and Resilience Amidst all of the wreckage along the road where the composite poles were installed, the only pole damaged was the steel pole with two breaks. In other words, the composites held their designed load, plus the ice, plus a portion of the load formerly carried by the steel pole across the street. This was possible because of the high amount of elastic strain energy composite poles are able to absorb in high-load situations. Needless to say, the strength and resilience of these poles in such harsh conditions were both surprising and impressive. This wood pole was used to replace a steel pole that was damaged by the ice storm, because there were no composite poles in stock. As a result of this very positive experience, WKRECC decided to install three large-diameter composite poles to carry the lines out of a new substation considered to be in a critical location. Again, the assembly and installation of these poles were quick and straightforward. Not long after the substation project was completed in September 2009, WKRECC ordered 20 additional RS distribution poles to be part of a new 7.2-kV distribution line that is about 8000 ft (2438 m) of 397-kcmil spacer cable. The contractor’s feedback was that the lightweight composite poles were easy to handle and easy to set. The composite poles have to be drilled to fasten framing to them, and the contractor drilled these holes easily in the field. Assembly went quickly, the wire was strung, and the line was put into service soon thereafter. Ice buildup on a typical three-phase pole. After the extreme weather events it has experienced recently, WKRECC now must consider more than just the initial capital costs in its purchasing decisions when buying poles. As mentioned earlier, shipping and installation costs with composite poles are less than that of wood poles. There is also the strength factor, which certainly plays a role in ensuring reliability and lowering maintenance costs. Unlike wood poles, composite poles do not require derating over time. In fact, their superior strength allows greater flexibility when retrofitting larger-sized conductor or for placing poles farther apart when using low-sag conductors. Construction Pluses Because RS composite poles are hollow, they require different installation methods and hardware. Hardware is now

DOWNLOAD PDF SCE needed a wildfire hardening solution for poles to support its heavier covered conductor. By Clinton Char and Brian O’Keefe, Southern California Edison, and Galen Fecht, RS Technologies Inc. A recent study by the journal Nature predicts an increase in the length of the California fire season from 36 days per year up to 58 days or 71 days, depending on moderate and high emission scenarios, respectively. An extended fire season means the threat of fire will start earlier in the spring, when historically there has been enough moisture to reduce fire threats, and extend later into the fall, which is particularly challenging considering the problematic combination of strengthening regional Santa Ana winds, which are associated with the lowest relative humidity of the year in Southern California, and already dry vegetation. High fire threat areas (in red and orange) in SCE service territory Confirming this ominous trend, in the last five years, California endured 13 of the 20 most destructive fires in the state’s history. With larger and more devastating fires now becoming the new normal, the term gigafire has emerged to label fires with over 1 million acres (404,686 hectares) burned. With 5 million customers in a 50,000-sq mile (129,500-sq km) service territory consisting of 4300 distribution circuits over 91,000 miles (146,450 km) of lines, Southern California Edison (SCE) has clearly mapped out high fire risk areas and understands the need for an effective fire-threat mitigation strategy. Prevention is one component of SCE’s strategy, manifested by the replacement of bare conductor with an insulated, covered conductor. However, with 1.4 million poles in its grid – most of which are wood – SCE also needed a proven wildfire hardening solution for poles to support the new, heavier covered conductor. Resilient Material Although it is the most prevalent material for distribution poles, wood is combustible. Steel poles are conductive and, in studies conducted by SCE, have the low potential to initiate wildfires under certain conditions. Concrete poles are too heavy to install in the remote areas of SCE’s service territory. Because they do not support combustion and they are the most wood like (that is, they can be drilled in the field), composite poles quickly emerged as a front runner for consideration in SCE’s wildfire-threat mitigation strategy. Two general polymer categories exist: thermoplastics and thermosets. Thermoplastics, also known generally as plastics, are items like a water bottle or the molded bumper cover on a vehicle. They are formed from pellets or powder using heat. Thermoplastics are not structural materials, so they melt when exposed to heat. Thermoset materials are entirely different than thermoplastics. Thermosets are composed of two components – a resin and hardener – that are mixed to create an exothermic reaction resulting in an irreversibly cured solid. When combined with a reinforcing fiber like nonconductive electrical glass, or E-glass, a structural element known as fiber-reinforced polymer (FRP) composite is created. Because thermosets do not melt when exposed to fire, they maintain their form. The non-combustible performance characteristics of composite materials are widely understood. However, extreme fire exposure can be the ultimate test for any material type. Full-Scale Test Method Flame temperatures recorded during the 3-min RS-Ackerman fire test. Although composite materials do not support combustion, their surface can char with sufficient heat flux exposure. Historically, flammability tests for polymer materials relied solely on laboratory-based tests initially designed for the home appliance market. While effective for their intended purpose, these coupon-scale tests did not realistically simulate the intensity of a wildfire, which has been described by wildfire survivors as a huge wall of fire. Going back to 2011, composite pole manufacturer RS Technologies set out to design a full-scale test that would represent a severe wildfire moving through a utility line right-of-way. Partnering with a fire expert from the University of Alberta, Mark Ackerman, a test method was developed. The test parameters were established based on known wildfire characteristics: Peak heat flux (energy) of 22 Btu/sq ft (250 kW/sq m) Maximum temperature of 1472°F to 2192°F (800°C to 1200°C), with most fires below 1832°F (1000°C) Exposure durations ranging from less than 30 sec for grass-fueled fires up to 90 sec for heavy coniferous forest fires, with most wildfire residence times in the 45-sec to 60-sec range. The total heat flux, or total amount of energy, of the fire depends on many factors, including fuel type, quantity, moisture content and fire duration. The RS-Ackerman full-scale fire test method starts with a full pole embedded in the ground, with an embedment depth consistent with an installed pole. Next, a 10-ft (3-m) tall steel shroud is installed around the base of the pole. The shroud has three holes spaced at 120 degrees around the base, which allows for three propane-fed burners to deliver the flame exposure. Typically, the test is run for either a 2-min burn or 3-min burn. This establishes the performance on both severe and extreme fire scenarios, respectively. The peak temperature of the test is 2332°F (1278°C) with a total heat flux of 16,540 kW-s/sq m, which is applicable for the 3-min exposure version of the test on the RS Fire Shield, a composite shell made from the same materials used on any round cross-section pole, including composite poles, to provide extreme fire protection. After the exposure duration has been achieved, the fuel source is turned off and the steel shroud removed. RS-Ackerman fire test method setup. The RS-Ackerman test duplicates both radiative (the transfer of heat without any physical contact) and convective (the transfer of heat from one place to another by the movement of air) heat flux exposure. Utility pole heat flux exposure depends on whether the energy transfer is purely radiative, where the surface is not contacted by flames, or a combination of radiative and convective. Perhaps the most important element in the RS-Ackerman fire test is the post-fire exposure strength test. After the steel shroud is removed, the complete pole is extracted from the ground and loaded into a test fixture to complete a vertical full-scale bend test to failure,

DOWNLOAD PDF A lightweight, modular composite pole being assembled for a wetland installation By Galen Fecht, RS Technologies Inc. There is now a high-performance composite alternative to those ubiquitous wood utility poles that line our streets and sidewalks. The humble utility pole, or telephone pole as it is commonly referred to, carries more than just telephone lines. In fact, any given utility pole will typically support a host of essential services like electricity (i.e. hydro power), voice, and data communication that are critical to empowering our daily lives. Wood poles have been used for over 175 years and, in that time, they have done a decent job of supporting overhead line networks. But times are changing. The “old growth” wood poles of yesterday were stronger than they are now. First generation poles were treated with preservative chemicals like creosote to slow down rot, whereas today’s wood pole is likely to be a less dense, tree farm-sourced pole treated with less effective preservatives, with less strength, higher deflection, and requiring earlier replacement. This shift in wood pole performance, coupled with the increasingly severe weather and environmental events that many of us are experiencing (think of wildfires and hurricanes), makes the case for pivoting to a more resilient and longer lasting type of utility pole. Steel and concrete poles are alternative choices, but they have their respective drawbacks. Steel poles are subject to corrosion and are conductive, which presents challenges for utility line crews performing live line installation and maintenance work, and public safety risks when there is an insulator fault. Concrete poles are extremely heavy, which complicates logistics and installation procedures. So, what else is available as an alternative to the status quo? The answer is composite poles, which are light weight and deliver reliable, engineered performance. These tubular poles are also known as fibre-reinforced polymer (FRP) or fibreglass poles. Composite poles are comprised of structural fibres, from which the pole derives it strength, and a thermoset resin, which is the “glue” that transfers load stress to and between the fibres. Although composite poles have been in use since the 1960s, it is only within the last 10 years that they have been more widely adopted by electric utility and communication companies. While many factors are driving increased adoption, the rationale can be boiled down to the fact that composite poles solve many of the problems that afflict wood, steel and concrete poles. What about cost? Are composite poles more expensive than wood poles? A 40 to 50 ft. composite pole commonly used in an overhead electric distribution line will typically be three to five times the cost of a comparable $500 wood pole. But, as with many things we purchase in life, up front price isn’t the entire story. Planning, engineering, labour, transportation, equipment, inspection, and maintenance costs for that $500 wood pole typically add up to about $9,500, bringing the total wood pole cost to $10,000 or more. Comparatively, the installation of a $2,500 composite pole is about $12,000, which represents only a 20 per cent premium on a total installed cost basis. For pole lengths beyond 50 ft., there is a negative correlation between cost difference and pole length for wood poles and composite poles (i.e. as pole length increases, the cost difference reduces). As we will see, in many situations, this extra cost more than pays for itself. A three-year old, structurally compromised wood pole riddled with woodpecker holes and displaying five instances of woodpecker hole remediation attempts (the plastic wrap on the pole) One reason to use a composite pole instead of a wood pole is simply because wood poles do not last as long as they should. On average, wood poles are expected to last 40 years. However, there are some installations where a wood pole will last only a fraction of that time before it needs to be replaced. In North America, woodpeckers and pests like carpenter ants are responsible for hundreds of millions of dollars in damage to wood poles annually. In some instances, a wood pole can be structurally unfit to support its initial design load in only two or three days after its installation if it is aggressively targeted by woodpeckers. Should that happen to a wood pole, another $10,000 investment is required to again replace the compromised wood pole. Woodpeckers, ants, and other wildlife can’t damage a composite pole. Replacing the woodpecker damaged wood pole with a composite pole eliminates the need to replace the pole for the next 80 years, which is the average service life of some composite poles. Appreciating that woodpeckers are territorial, a composite pole is a good investment to mitigate future damage and frequent replacement costs. Premature rot is another situation when a wood pole might not last as long as it should. Because utility poles are embedded into the ground, accelerated wood rot often occurs in wetland areas or regions with high water tables. The use of a composite pole solves the rot problem and, in these applications, is also a superior choice from an environmental perspective. Composite poles also do not contain harmful preservative chemicals that ultimately leach into the ground from wood poles. This makes composite poles an excellent choice in areas where drinking water wells are located, or in sensitive wetland environments. Speaking of wetlands, these areas typically need specialized equipment to install utility poles, such as tracked vehicles or mobile cranes, and often require swamp mats to facilitate site access. These are additional time and cost considerations that can easily double the installed cost of a pole. This example leads to another reason to use composite poles: where the total installation cost is higher than average. The more remote or off-road a pole location is, the higher the cost to install and maintain that pole. Because composite poles are about 1/3 the weight of a comparable wood pole, lighter duty equipment can be used which typically results in a lower installed cost for a composite pole compared to a wood pole in remote locations. Yet another application for high-performance composite poles is where reliability is paramount.