Squirrels cause fewer outages as Municipal Utilities buries more power lines

WILLMAR -- Squirrels are causing fewer power outages in Willmar as more electrical lines in older residential areas are placed underground.

Squirrel outages aren't a problem in newer residential areas where power lines are routinely buried.

"We very, very seldom build overhead anymore,'' says Jeff Kimpling, manager of electric services for the Willmar Municipal Utilities.

Larger lines, such as the one along Willmar Avenue, form the city's power backbone and are expensive to bury.

"When there are problems with them, we want to be able to see where the problems are and make repairs faster,'' said Kimpling.

Since the utilities' underground conversion project began 27 years ago, the percentage of miles of overhead electrical lines decreased from 72 percent in 1980 to 18.5 percent in 2007.

During the same period, the percentage of underground miles increased from 28 percent to 81 percent. New construction accounts for some of the increase in underground miles.

"Our miles are going down, but we're only taking off maybe a mile (per year),'' says Kimpling. "Each year we're going down. Most years we're in that mile area (where) we get rid of that much overhead.''

Squirrels, which account for many outages, are sometimes seen scampering on the lines. How are they able to do that with no apparent difficulty?

The answer lies in the way electricity travels, always following the path of least resistance between two points.

In many cases, high-voltage power lines are not insulated, and the animals on the lines are coming into direct contact with the electricity but are not interrupting its flow.

It's only when the animal bridges the gap with its body -- say it touches the line and a grounded piece of equipment like a transformer -- that the electricity will follow the easier path of conduction and pass through the animal.

The contact blows a fuse on the pole, knocks out the power and kills the squirrel.

"We usually can find them on the ground within 10 feet of the pole where they have fallen off the pole,'' says Kimpling.

All outages -- whether caused by squirrels, vehicles hitting power poles, faulty wires or tree branches -- are recorded.

"A squirrel got into the line here, here and here, and it's these records that we use to work on our conversion project,'' he said.

Squirrels caused 43 outages, or about one-third of all outages, in 2003, including some on the east side where squirrels were hiding walnuts on top of three crowded transformers behind Domino's Pizza. The outages cut power to many east side customers.

Kimpling said the squirrels "kind of like it on top of those transformers because the transformers generate heat and it's nice and warm up there, plus it's a flat spot where nobody's going to find their walnuts. They're creative little buggers on where they want to hide things.''

In the fall of 2004, the utilities solved the problem by burying the power lines. One thankful customer was Domino's owner Bill Graves.

"Before they fixed what they fixed, it was a problem probably once every couple of weeks, and it seemed to always happen on a Sunday, and it seemed like they always had to get called out to fix it,'' Graves said.

"Since they fixed whatever they fixed, it has never been a problem.''

Graves appreciated the utilities' work.

"We're lucky to have a local power company in Willmar because they seem to take better care of you than most of the other towns we're in where we deal with NSP or other places,'' said Graves.

In 2006, the utilities converted overhead lines on Second and Third Streets Southwest between Trott and Willmar Avenues. This area in 2005 accounted for eight squirrel outages, according to Kimpling's annual reliability standards report to the Willmar Municipal Utilities Commission.

Conversion continues on the east side this year. Barring unforeseen difficulties, overhead lines could be gone by 2012.

Besides eliminating contacts with animals, conversion significantly reduces exposure points for lightning, wind, trees and human contact, although the latter seldom happens.

Burying power lines is good business, says Kimpling.

"We know if we've got to rebuild something that it may be cheaper in the short run to build it overhead,'' he said. "But in the long run, (with) convenience to people, exposure and our outage times, it pays off in the long run.''