An overheated unit at Yukon Energy's Aishihik facility was the cause of this morning's massive power failure on the Whitehorse/Aishihik/Faro grid.

Power to the entire grid was lost shortly before 9 a.m. It was fully restored to all customers with the exception of the Minto Mine by 10:30 a.m., said Yukon Energy spokeswoman Janet Patterson.

In Whitehorse, residents bracing -28 C cold went through the customary drill of coping without bank machines, store cash registers and darkened traffic lights at intersections.

When a power unit overheats, it's programmed to shut down to ward off damage, Patterson said.

The corporation was unable to provide energy to the mine, with officials there opting to go on diesel at around 11 a.m.

Patterson said the corporation remains unsure why the mine couldn't be brought back on line, but technicians are continuing to work on getting it back on.

While Yukon Energy officials remain uncertain about what caused the unit to overheat this morning, Patterson said staff are running it at a lower capacity now.

"We're treating it with care."

Meanwhile, as the corporation brought customers back on line, it had to let more water through its dam into the Yukon River, which had high water levels last week due to the amount of ice near Rotary Peace Park.

The high water levels saw a portion of trail close last week.

This morning, Patterson said that while more water had to go through the dam from the outage, the water levels had gone down somewhat from last week, so there wasn't a major issue with the additional water.

She also noted the corporation acknowledges the power outages have been too frequent of late, with the most recent occurring on Jan. 14.

Yukon Energy is now proceeding with its plan to address the issue. The plan, established after the major outage during the 2008 Thanksgiving weekend, includes more frequent maintenance and replacement of equipment, she said.

Yukon Energy was not the only organization dealing with overheated equipment this morning in losing power.

CBC radio listeners who may have expected to hear information on the power outage were left with dead airwaves when the station's generator failed shortly after the power outage.

Station manager John Boivin said the generator came on fine when the power went out.

It was about five minutes later though that, like Yukon Energy's equipment, it turned itself off when the motor began overheating.

"It's not something they've seen before," Boivin said after radio technicians had investigated the situation.

The generator hasn't failed the radio network in recent memory, operating throughout the many power failures over the past few months.

While the generator was fired up again during the outage, it quickly shut down.

"This is a real concern," he said, noting staff are continuing to look into it to find out what's causing the motor to get too hot.

Since it serves a broadcaster, the generator is in place to provide information to listeners during emergency situations, he pointed out.

The situation had Michael Templeton, the territory's manager of the Emergency Measures Organization, planning to contact the CBC this morning to find out what had happened to cause it to go off the air during the outage.

While the territory relies on the radio station to relay information during a prolonged outage or emergency, Templeton said, in emergency situations where broadcasters aren't available, the territory has a back-up plan for communication.

Along with an FM transmitter which allows the territory to broadcast to a small area in cases of emergency, officials would also work with the amateur radio association to get their message out in an admittedly more "old-fashioned way," he said.