A failure with the fourth wheel hydro generator caused a power outage late last night, and again early this morning.

Yukon Energy spokeswoman Janet Patterson said the first outage occurred at 11:11 p.m. Sunday and blacked out Riverdale for 14 minutes, and Porter Creek North, Crestview and sections along the North Klondike Highway for 16 minutes.

A bus bar, or conductor that transfers power between the generator and breaker, melted and caused the number four generator to shut down, she said.

'We do not know why but we are trying to find out,' Patterson said of the investigation into the bus bar failure.

She said the power was restored after the number three hydro generator was turned on to augment the power being generated at the Aishihik dam.

The second outage occurred at 4:27 this morning after a crew completed the necessary repair to number four, though the system went down again when number four was put back on line, for reasons unknown, she said.

Patterson said Riverdale was without power for 36 minutes and Porter Creek North and beyond were blacked out for 41 minutes.

Power was fully restored when number four was successfully brought on line, she said.

The Aishihik dam, with capabilities to generate a maximum 30 megawatts, has been turned down 19 megawatts because of the problem it suffered that caused the massive blackout of Jan. 29. That failure left some without power for up to nine hours in cold conditions.

Patterson said if you look back over the last couple of years, Yukon Energy's power supply has been stable. But it just takes a couple incidents like this morning and last night, and the huge blackout two weeks ago, and people begin expressing their frustration with the system, she said.

Patterson said Yukon Energy also feels the frustration and has a group of people who will be looking at the situation.

Number four is the largest generator on the Whitehorse-Aishihik-Faro system, with a capacity to put out 20 megawatts, while the number one, two and three turbines each have a capacity to generate six megawatts.

Patterson said number three alone was able to pick up the slack when number four went down because of the typically low loads at the time of night combined with the warmer temperature required less juice for electrically-heated homes and buildings.