A failure of wires feeding the Faro mine site caused a systemwide power outage at 2:23 Tuesday afternoon.

Yukon Energy engineer Lawrence Joudry said this morning large wires feeding the mine from the transformer caught on fire, according to eyewitness accounts from those working at the mine site.

The wires are old, and when the weather starts to change as it has, the fluctuation in temperature creates more moisture in the air and problems can arise, he said.

Joudry said exactly what happened is still under investigation.

When the wires failed, the built-in protection device which should have signalled a failure did not do its job, he said.

As a result, Joudry explained, the entire Whitehorse-Aishihik-Faro grid kicked into high gear to try to feed an additional load that wasn't there, before additional protection devices shut down the system to prevent further damage.

When the number four hydro turbine at the Whitehorse Rapids Dam went down, it was followed by two diesel generators at the dam and then the two hydro turbines at the Aishihik dam, he explained.

"Once we lose number four, we're in a bad situation, but it behaved the way it was supposed to,” Joudry said.

Power to the entire grid was knocked out, with most customers back on an hour and 22 minutes later, at 3:45.

Power to the smaller communities serviced by backup diesel generators – Pelly Crossing, Haines Junction, Carmacks, Ross River and Faro – was restored within minutes of the blackout.

Carcross was back on the grid 18 minutes afterwards at 2:41, and Porter Creek was the first area of Whitehorse powered back up, at 2:52.

Some among the handful of customers between Carmacks and Faro were out until 9:30 last night.

Joudry said restoring the grid requires turning on sections one at a time as generation becomes available, to avoid any significant changes in load and supply which would trip the system again.

Bylaw officers were out directing traffic not long after the lights went out.

Most retailers shut their doors and an international salmon conference at the Westmark Whitehorse Hotel called it a day just over an hour into the outage.

Students at Yukon College were dismissed at 3:30 p.m., though once power was restored, staff quickly got the word out evening classes were on as scheduled.

For the president of the Whitehorse Chamber of Commerce, it was the same story this morning.

Power outages cost money – lots of it, said Rick Karp.

In these times of growing demand for energy, Karp said, it's becoming more and more apparent that consumers have a key role to play in conservation, as a means of promoting efficiency and reliability.

As much was emphasized earlier this month during the three-day charrette hosted by Yukon Energy to explore the territory's future energy supply and demand.

Karp said just as consumers have a responsibility to do their part, however, so too does Yukon Energy have a part to play in ensuring its system of generating and delivering electricity is reliable.

Power outages, he said, are particularly hard on the business sector, and literally cost tens of thousands of dollars.

At his Main Street hair salon, Karp estimates he lost about $500 in business and the need to replace a new routor and modem.

Restaurants with food on the grill don't only lose the order, but most likely the customer, he said.

Karp said sometimes it can boil down to question of whether to send staff home.

Retailers who rely on electricity to run their debit and credit card services are not only out of luck until power is restored, but in Tuesday's case, they still had to wait longer until Northwestel Inc. did what it had to do to boot back up, he said.

Northwestel spokeswoman Sunny Patch said this morning its DSL service remained on line throughout the outage and those with battery backup for their customer service machines were unaffected.

The company's cable and wireless Internet service remained available for about half an hour after the blackout, powered by a backup generator. It went down at 2:54 but was available again shortly before 4 p.m., she said.

Yukon Energy's engineer said the publicly owned corporation has taken steps to build extra protection into the grid to avoid systemwide problems when issues arise in specific areas.

When a line problem arose this past winter, he pointed out, the system did exactly what it was supposed to do to: isolate the area.

Joudry explained that had the protection device at the mine site functioned as it should have, the problem would have been isolated.

Yukon Energy spokeswoman Janet Patterson said in 2010, there were nine outages related to Yukon Energy's services, two of which were system-wide.

So far this year, there's been two, the partial earlier this winter and Tuesday's, she said.

In 2009, Patterson pointed out, there were 13 outages, and 19 in 2008.

The Faro mine opened in 1969 and closed permanently in 1998, though mine reclamation work is continuing at the site.