Anatomy of a Sisters Country outage

2:34 a.m., Tuesday, December 8.

It's cold. Bitter cold. An arctic blast has dropped temperatures in some parts of the Sisters Country to 20 degrees below zero.

Along the power line running just west of Tollgate there is a blinding flash: a socket-eye connector, rated to 50,000 pounds, has cracked. The line falls to the ground, instantly taking out power and sending a cascade of effects back along the Central Electric Cooperative transmission line that runs from Cline Falls to Tumalo and up into the Sisters Country.

On Fryrear Road, a line breaks and fuses itself to a steel pole. At the Cline Buttes Substation, a gas vapor breaker, probably affected by the extreme cold, fails to function properly.

Power to 3,000 accounts from Tumalo to Suttle Lake is dead in the middle of the sharpest cold snap in recent memory.

Not everyone in the Sisters Country is affected. Accounts served by the Redmond-Sisters transmission line and the Sisters substation on 115- kv power "held perfectly," according to CEC spokesman Alan Guggenheim.

The Tollgate substation is not on 115kv yet, though a brand-new substation is now online. Once that transition happens, in about a year-and-a-half, Guggenheim says, power will be more reliable and it will be easier to recover from catastrophic equipment failures like the December 8 outage.

"The capacity or the service we get from 115kv is just so much better than 69-kv," Guggenheim says. "That's why BPA (Bonneville Power Administration) is shifting to 115kv."

CEC crews mobilize by 3 a.m. and quickly identify the three crisis points. But the line breaks and breaker failure are not their biggest concern. Experienced line crews tell their management that restoring power after the damage is repaired is going to be slow and arduous.

"The repairs are not going to be a problem," Guggenheim says. "It's the cold-load pickup."

When the power goes out, every household that runs on electricity - furnaces, water heaters, appliances, lights, goes dark and cold. As power comes back up, all those appliances come on. The load is too heavy for the system to bear all at once.

So power must be nursed back to life, a few houses at a time. Crews literally have to wait for water heaters and furnaces to heat up to a point where they can shut off before moving on to new accounts.

When houses have been sitting unheated in a deep freeze, that takes a long time.

Crews quickly advised that it would take 24 hours to bring everyone back up.

The Sisters-Camp Sherman Fire Department and Deschutes County and Jefferson County Sheriff's Offices mobilize to prepare for a voluntary evacuation of citizens who could not comfortably wait out an overnight outage.

"I really gained a lot of respect for (Fire Chief) Tay Robertson and his leadership and for the sheriff's department," Guggenheim said.

The Red Cross opened a shelter at Sisters Elementary School.

As it turned out, not many evacuated.

"I think that says something for the self-reliance and the hardiness of the people who choose to live here," Guggenheim said.

By sundown on Tuesday, crews have restored power to 70-80 percent of the accounts. Work progresses westward up the line from Tumalo, with accounts furthest west enduring the longest period without power.

Within the 24-hour window, power has returned to 90 percent of the affected accounts.

"Cold-load pickup hampered operations all night," Guggenheim says. "Line crews experienced severe conditions, fatigue and the usual mechanical problems with truck heaters, diesel engines, dropped tools, cold, hunger, and the thousand things that go wrong in the dark when it's 10 below zero. But not one stopped working and we had no reported accidents or injuries, thank God."

The last 10 percent takes another 12 hours and isolated problems continued into Thursday.

As temperatures slowly climb back into "normal" ranges, Sisters Country residents deal with broken pipes and other fallout from the cold snap - and luxuriate in their warm showers and enjoy their Christmas lights.