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  • 21 Oct 2014

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Adventurous squirrels give region's power grid a shock

Wildlife-related power outages are on the rise, eclipsing vegetation such as falling limbs


When the power goes out on a hot day, most people assume overuse of air conditioning is to blame.

But from June 12 through July 7, four substation outages in Portland’s westside suburbs and in North Portland were caused by adorably nimble, fluffy-tailed and overly adventurous squirrels.

All four outages were in PGE territory and one — the Oak Hills substation at Northwest Cornell Road and Twin Oaks Drive in Beaverton — was hit twice. (By different squirrels, of course.)

“This is clearly an unusual convergence of squirrel activity,” said Steve Corson, spokesman for PGE. “We’d like to have a break from squirrels for awhile.”

Here’s the run-down of PGE’s squirrel-related outages in recent weeks, affecting tens of thousands of customers:

• June 12, Six Corners Substation, affected 10,400 customers in Sherwood and Tualatin from 4:20 to 8:15 p.m.

• July 2, Northwest Cornell and Twin Oaks substation, affected 10,000 customers in Beaverton, Hillsboro, Cedar Mill and Bethany from 6 to 10 a.m. The newsroom of KPTV went dark during its morning show, but the broadcast continued, powered by generators.

• July 6, North Portland, more than 8,000 customers affected in Kenton, Arbor Lodge and St. Johns areas, 8 to 10 a.m.

• July 7, Northwest Cornell and Twin Oaks, affected more than 8,000 customers in Beaverton, Hillsboro and Cedar Mill areas. 8:15 to 10 a.m. Two car wrecks occurred on Northwest 185th Avenue in Hillsboro after the traffic lights went off. One driver did an illegal U-turn and hit a vehicle driven by a Washington County sheriff’s deputy.

The outages left many customers in the affected areas wondering how sweet-faced little squirrels could cause so much damage.

“It’s not all that unusual to have wildlife that does damage," said Corson. “But some years, there’s more squirrel activity than others.

“Normally, vegetation and tree limbs are more of a problem. But last year was the first in recent memory that squirrels accounted for 18 percent of outages and vegetation only 17 percent.

“We have a huge tree-trimming program, which limits problems with vegetation but also controls wildlife getting into substations.

“We have an ongoing program of mitigation using squirrel guards of different shapes and sizes. One of the common ones is where a rubber cup goes over the insulator and out over the wire.”

The Cornell substation, which has been hit twice, is receiving extra attention to prevent a a squirrel-outage trifecta.

A common misperception is that squirrels running across a single power line can cause a problem. Tom Gaunttt, spokesman for Pacific Power, explained that it’s not a squirrel high-wiring on a single line on your street that causes the problem. In a substation, he said, “Yes, a squirrel runs across a line but if they touch two, even a claw on one wire and a flick of a tail on the other,” conduction kills the squirrel and knocks out power.

Pacific Power hasn’t had any squirrel-related outages in recent months, but he said doves and snakes have caused problems in less populated areas. “It kind of goes in waves.”

On the bright side, Corson noted that wildlife-related outages are easier and quicker to repair than other outages. “They don’t damage equipment much,” said Corson.

In terms of duration of all outages, wildlife-caused incidents account for 6 percent of time off-line, while vegetation (fallen tree limbs etc.) account for 21 percent of down-time.