Yukon Energy Corporation officials are still investigating the cause of Sunday night’s 4.5-hour blackout.
But preliminary findings suggest failed power line insulators caused the widespread outage, said Steve Blysak, the corporation’s assistant control room operator.
“It’s not smoking-gun proof, but we think that cracked insulators are a pretty likely source,” said Blysak.
The blackout began about 10:50 p.m. and hit all communities throughout the southern Yukon from Teslin to Faro, said Yukon Energy spokesperson Janet Patterson.
In total, 12,000 homes and businesses were deprived of power.
Power was restored to all users by 3:30 a.m., said Patterson.
Using a helicopter on Monday morning, a Yukon Energy employee identified an area close to Whitehorse General Hospital as the potential source of the trouble.
Sunday afternoon’s snowfall could have caused the insulators to fail, said Blysak.
“When a line is subjected to abrupt temperature changes, it can easily cause lines to fail,” he said.
However, it may be very difficult for officials to pinpoint exactly what caused the insulator to fail.
Weather, tree falls, animal contact and even bullets — people use them for target practice — can cause failures, he said.
“If somebody shoots at your power lines, there’s very little you can do to prevent that.”
Insulators are “always a bit of an issue,” said David MacDonald, vice-president of operations and engineering at Yukon Energy Corp.
Yukon insulators are “no different than anywhere else in the world,” but their porcelain construction makes them extremely brittle and, if they get dirty, it can interfere with their proper operation, said MacDonald.
However, “when you consider the hundreds of thousands of insulators in use on the Yukon system, we really don’t have that many problems with them,” he added.
The suspected faulty line is currently dead, the power is being rerouted through other channels until repairs can be made.
“Our next step will be to get a crew mobilized and replace the insulators on that stretch of line,” said Blysak.
The problem should be completely repaired by Wednesday afternoon, said MacDonald.
Sunday night’s blackout was the first of the year on the Whitehorse-Aishihik power grid, said officials.