by Whit Gibbons

July 22, 2012

I have dealt with regional power outages twice recently. One was on a trip through storm-ravaged Virginia and Pennsylvania where the landscape was littered with broken trees. The other was in Georgia where electrical service to a region had been temporarily shut down for the third time in a month. No limbs were scattered about in Georgia. Instead, on the ground below a power substation was a large, electrocuted snake.

In towns, local power failures are often caused by squirrels that get into pole-mounted transformers. The impressive boom can generally be heard several blocks away. When it occurs in a transformer across the street, it can sound as if a plane has just crashed in the front yard. The result is analogous to the neighborhood's blowing a fuse. All power is gone to several houses in the area. Sometimes, the charred remains of the squirrel can be located.

In certain areas of the rural Southeast, electrical substations can suffer power outages that affect even larger areas. Substations are enclosed by chain-link fences and contain a lot of scary looking transformers, coiled insulators, and high-voltage transmission lines. A vast amount of high-powered electrical current passes through a substation, and even prankish kids know better than to play around inside the fence. Other animals, however, do not, and they can cause problems. A six-foot-long snake is able to climb and has a reach long enough to simultaneously touch an energized connector and a grounded conductor, such as a metal beam, that is several feet away. The electrical damages can be serious and widespread, affecting power distribution patterns to an entire region. The snake, of course, is dead.

I was shown several photos last week of crispy dead snakes that had fallen to the ground around a substation in rural Georgia. I was asked the questions you might expect. What kinds of snakes are they? Why are they climbing up into the substation structure? What can be done to stop them? Regional power outages can cost millions of dollars each year, so the search for answers to such questions is not a trivial undertaking.

Even before I looked at the photographs, I suspected the culprits would be rat snakes, based on the knowledge that they are expert climbers and very abundant throughout the Southeast. They will climb high into trees or onto man-made structures, including buildings, bridges, and power poles in search of birds, eggs, and rodents. They can easily climb any tree, wall, or other structure where rough surfaces are available and prey is likely to be found above ground. Pertinent to substation problems, a rat snake is able to climb a guy wire or a wooden telephone pole with no problem, albeit slowly. Rat snakes use their belly scales to gain purchase on any rough surface, including brick walls and the bark of pine or oak trees.

The emerging problem with rat snakes is reminiscent of the millions of dollars in electrical damage caused by brown tree snakes on the island of Guam. According to the U.S. Geological Survey, "power failures, brownouts, and electrical surges . . . damage electrical appliances and interrupt all activities dependent on electrical power, including commerce, banking, air transportation, and medical services." On Guam, more than 1,600 power outages occurred over a 20-year period.

How will southeastern power companies deal with what appears to be a burgeoning problem of power outages caused by rat snakes? The knowledge gained by scientists who have worked with brown tree snakes on Guam will provide some guidance as the companies struggle with the problem of tree-climbing snakes. However, a comprehensive solution for preventing rat snakes from causing power outages in the Southeast is still forthcoming. It will be dependent on future research findings, continued studies of rat snake behavior, and investigations into how to prevent the snakes from climbing substation structures.

One thing is certain. In the Southeast, enough personal and commercial damage is caused by electrical power outages resulting from regional storms without adding outages caused by snakes.

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