US Electrical Grid Vulnerable to Squirrel Attacks

In an intriguing article for the New York Times, Jon Mooallem, described his fascination with power outages caused by squirrels in the US, and explained that they are far more common occurrences, and a far larger problem for power grids than many might think.

His interest was first piqued in April after reading about a squirrel that had electrocuted itself on power lines in Tampa, Florida, knocking out the power to 700 people. Then since Memorial Day he recorded 50 separate incidents across 24 states in which squirrels caused power cuts.

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In June, on just two days, squirrels were responsible for power cuts to 1500 customers in Mason City, Iowa; another 1500 in Roanoke, Virginia; 5000 in Clackamas County Oregon; and 10000 in Wichita, Kansas.

Squirrels have also been responsible for knocking out the power to a regional airport in Virginia, a Veterans Affairs medical centre in Tennessee, a university in Montana, and a Trader Joe’s in South Carolina.

Mooallem went on to describe how just “five days after the Trader Joe’s went down, another squirrel cut power to 7,200 customers in Rock Hill, S.C., on the opposite end of the state. Rock Hill city officials assured the public that power outages caused by squirrels were “very rare” and that the grid was “still a reliable system.” Nine days later, 3,800 more South Carolinians lost power after a squirrel blew up a circuit breaker in the town of Summerville.”

As you can see, there are far more lives affected by pesky squirrels than you may have originally thought.

Whilst precise data on squirrel related power outages is very rare, Austin Texas claims that squirrels were culpable for 300 outages last year, and some other utilities blame wild animals for 7 to 20 percent of their power outages. In 2005 the State of California estimated that wild animals cost the local economy between $32 million and $317 million a year.

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Matthew Olearczyk, a program manager at the Electric Power Research Institute, explained to Mooallem that squirrels often cause blackouts by running along power lines and accidently toughing, at the same time, a component carrying an electrical current, and an earthed object. The squirrel then completes a short circuit creating an arc that with a flash incinerates the hapless squirrel. The electric grid is then designed to recover and resume the flow of electricity through the lines, however if the dead squirrel does not fall then it will just keep creating the short circuit, preventing the natural flow of electricity along the cables, and eventually causing damage to transformers or local electrical equipment.

A squirrel scampering across a power line. (oddball daily)

Moolamer also spoke to John L. Koprowski, a squirrel biologist at the University of Arizona, and mentioned other reasons why squirrels seem so keen on attacking the electrical grid. “Squirrels chew through electrical wiring because the animals are constantly teething. An adult squirrel’s incisors never stop growing — they can grow as much as 10 inches per year — and the animals must chew constantly to keep them worn down. Squirrels gnaw or burrow their way into transformers for the same reason they enter rotting cavities of aging trees: hollow spaces offer them den sites and safety from predators. Squirrels break into equipment at substations because the seeds and insects they eat get sucked into that machinery by cooling fans, or are pooled inside by the wind. Mr. Koprowski described the flat tops of transformers as perfect spots for squirrel basking behavior, when squirrels sprawl out in the sun to warm up, or in the shade to cool down, and also ideal “runways” from which squirrels can start their flying leaps into the canopy.”

By. Joao Peixe of Oilprice.com