The Courier Electronic Edition

Long live the power towers


Q: What is the estimated lifespan of a large power-transmission tower? -- Warren R. Kahn, Findlay.

A: Is that tower out back looking a little rickety?

Relax. American Electric Power's steel transmission towers will last more than 100 years if properly maintained, says spokeswoman Shelly K. Clark.

Towers keep high-voltage lines separated from each other and their surroundings. There are four to six towers per mile.

A typical one stands about 100 feet high and weighs about 14 tons. The biggest can stand 150 feet and have crossbars 100 feet across.

"Our older steel towers on the subtransmission system were constructed 90-plus years ago and have life remaining," Clark said. "We also have ... lines that were constructed in the 1920s, such as the line that extends from South Bend, Ind., to Lima. I would expect those towers to last 20-plus more years without problems."

A tower's time is more dependent on its conductors and insulators, she said.

"Some types of conductors that were installed in the 1920s are reaching the end of service. Aluminum conductors with a steel core require replacement as the steel core corrodes.

"Also, the electrical capacity of older wires is a limiting factor. As the electric system expands or customer load is added, then electrical capacities of the wire are exceeded.

"Larger conductors are one solution. However, installation of larger conductors typically requires that the steel towers are replaced to support the increased structure loads.

"Generally, if the conductor and insulation require improvement, then the structures are also replaced.

"Severe weather conditions such as high winds of Hurricane Ike or heavy weight of ice as experienced in the January 2005 ice storm can shorten the life expectancy of the structures," Clark said.

Other reports say salt, coastal or inland, also is not good for towers.

For example, a 15-year study by an Australian engineering firm recently estimated steel towers in the Philippines last 55-60 years, steel or concrete poles last about 55 years, wooden poles last about 45 years, and transmission cables last 40-45 years.

And, a Canadian study in 1987 found that corn growing very near towers absorbs zinc and cadmium from coatings on the galvanized steel as the structures deteriorate. But, fear not: The study also said it was no threat to corn-fed animals or people. -- Peter Mattiace.

Q: What is the most frequently occurring community name in the United States?

A: It varies over time because names are added and changed. Most recently, it was Midway at 212 occurrences and Fairview at 202.

Springfield often is thought to be the only community name appearing in each state, but at last count it was in only 34.

The most recent count shows Riverside with 186 instances in 46 states. Only Alaska, Hawaii, Louisiana, and Oklahoma do not have a Riverside.

The U.S. Board of Geographic Names surveys named "populated places," including incorporated places (20 percent of communities), unincorporated places (the majority), housing developments not yet incorporated, and neighborhoods within incorporated places. -- U.S. Department of the Interior.

If your kind of curiosity leads to these kinds of questions, Just Ask will answer them on Mondays. Just ask by e-mail to justask@thecourier.com, by fax to 419-427-8480, or by mail to Just Ask, The Courier, P.O. Box 609, Findlay, OH 45839.