Just over a decade ago, Austin Energy (Austin, Texas, U.S.), a municipally owned utility serving 364,000 customers in central Texas, turned to steel distribution poles when addressing a tricky technical distribution problem. The utility's positive experience with steel convinced it to try the new material in other applications. Today, 90% of all new major power distribution projects at Austin Energy include steel poles in the design. A cost-benefit analysis confirmed that Austin Energy saves time and money with steel while increasing system reliability.
In the late 1980s, the city of Austin was in a period of explosive growth, booming with the birth of new technology companies and the dot-com rush, which led to the initial use of steel poles in the Austin Energy distribution system. However, at that time, Austin Energy was using a three-pole wood structure to turn angles instead of side guys because the state required the utility to be within the designated assignment of right of way, and its commercial customers didn't want to give up any more right of way than was absolutely necessary.
Austin Energy's typical three-pole wood installation was a headache in other ways, as well. It congested business access, its construction and maintenance was labor intensive, and the multiple-hole excavations and guy anchor installation increased the chances of underground utility conflicts. The utility had to devise a solution to turn these angles without all the poles and hardware.
Time and Labor Savings
Austin Energy conducted a cost-benefit analysis to review the total installed cost of the three-pole wood structure including materials, anchoring, hardware and labor, and compared it to a one-pole steel structure. The analysis found that the utility significantly reduced the time required to install the structure and showed savings of 50% to 73% on labor on the initial installations. Specifically, the labor cost to install the steel-pole structure was 64% less than the wood, and the material cost for steel was 15% lower even with the higher cost of the steel pole.
Economic analyses of other Austin Energy applications provided further evidence that integrating steel poles into its system was a cost-effective practice. For example, labor costs were 73% lower for a double-circuit 795 steel-pole application; material costs were 43% lower. This analysis is based on using one steel pole instead of three poles and anchors to turn angles.
Reliability and Longevity
With this positive report on the financial advantages of the steel distribution poles, the utility decided to move ahead with steel poles in other areas. Early on, the utility developed standardized drawings to expedite engineering and pole delivery. Engineering also produced a standardized unguyed angle load chart for distribution designers.
Austin Energy started looking seriously at using steel distribution poles in its highway crossings after a wood pole was struck by lightning and some conductor lines were dropped across a major highway. Austin Energy did not want a repeat of this experience, so it changed many of its primary highway crossings to steel. The utility wanted structures that could provide longevity and reliability, along with a pole that wouldn't deteriorate in the event of lightning.
Austin Energy retrofitted highway crossings with 70-ft (21-m) steel poles to support the inherently longer spans. At this height, the poles maintained clearance over multilevel highways and were comparable in cost to wood poles of the same height. The light-duty steel poles have worked well in multiple-pole installations placed along curved freeways with limited easements as well as in situations that require multiple unguyed turns.
The Aesthetics Factor
Austin Energy has found that the aesthetics of steel poles been a major plus with customers in locations where residences and commercial business parks are concerned with curb appeal. Weathering steel poles work well as replacement poles in established neighborhoods because the poles blend in with the existing line. Austin Energy sometimes gets requests for colored poles. In these cases, it paints over galvanized steel with the customer covering the painting costs. As a result, some customers will now allow the utility to place the project next to the street instead of in the rear property of the business.
Take for example the Steiner Ranch, a recently constructed residential development located in the hill country. Austin Energy made an agreement with the developer to use weathering steel distribution poles to build a double-circuit line along the road and avoid going into the canyons. Initially it was more expensive, but the utility will have better access to the line with lower maintenance costs. It is difficult and time consuming to change out any pole in the rear easement, especially in hilly areas.
Another situation arose where Austin Energy saved money avoiding an underground installation. The area was already outfitted with galvanized street-light standards. The utility went back with 65-ft (20-m) galvanized steel distribution poles, which were 20 ft (6 m) taller than the streetlight standards, and the commercial customers were completely satisfied.
Linemen Working with Steel
Steel poles are now a standard part of Austin Energy's distribution system, and the utility's highly trained lineman are well adjusted to working with the different types of poles.
Working with a live line was one of the big hurdles linemen encountered with learning to use steel poles. Linemen made some procedural changes to cover more of the conductor and cover the pole. Of course, the linemen always wear the proper safety gear when working with either wood or steel when they're setting a pole near an energized conductor.
Early on, linemen worried about how they could respond to trouble calls without climbing a pole. Austin Energy arrived at a fairly simple solution. It put steel poles in locations where linemen can always use bucket trucks. This means the utility doesn't need to add step bolts, which saves money. However, it does have a few steel poles that are stepped for special situations.
Configuring the Right System
Integrating the steel poles into the utility's distribution network has been a positive learning experience. It took Austin Energy about five years to figure out the best configuration for its system. The utility continued to use its standard hardware but made sure that it had the proper insulation properties. It added fiberglass deadend arms, fiberglass three-eared arms, the correct insulators and fiberglass ridge pins.
Whether or not the poles are delivered predrilled depends entirely on the project at hand. Each framing configuration is unique. Linemen may drill in the field or in the air, or order predrilled poles. When drilling, they use a bigger, heavy-duty drill to get through the thicker-plated structures. On the lighter tubular poles, they use a regular power drill.
Austin Energy typically orders steel poles by the project, which means careful and detailed advance planning. It works with the T&D design team upfront, which allows it to know exactly what is required in an installation and by when.
Today the utility typically orders poles in 5-ft (1.5-m) increments, and it usually orders two-piece poles for heights over 70 ft (21 m). This allows for easier transport to the job site. The two-piece strategy also eliminates the need for a permit. The utility has determined that, in some cases, steel poles are lighter than the wood pole of the same size, making them easier to handle.
Austin Energy stipulates in its contracts that steel pole suppliers deliver the steel poles between six and ten weeks after the order is placed, depending on the type of poles ordered. The majority of the steel poles are taken directly to the installation site, but Austin Energy maintains a small lay-down yard for steel poles so it has stock on hand for emergencies and rush jobs.
A Good Move to Steel
At least once a year Austin Energy gets calls from environmental groups asking it to use 100% steel to address concerns with preservatives and recycling, but the utility will always have both wood and steel in its distribution system. The more options the better. Steel has helped Austin Energy build a better distribution system, address problem issues and save money.
Jeff Padavick is the superintendent of transmission and north distribution at Austin Energy. With more than 22 years in the industry, Padavick is a leader in distribution system design and construction. He has been with Austin Energy for 19 years. Prior to joining Austin Energy, Padavick worked with various contractors.
Copyright Austin Energy.