By James Jelter
SAN FRANCISCO, Aug 15 (Reuters) - The head of the group that seeks to ensure reliable electric service said on Friday power would likely be restored by the end of the day to most customers following the biggest blackout ever to strike North America.
"All efforts are being concentrated now on restoration, then we'll turn to the investigation," Michehl Gent, North American Electric Reliability Council president and chief executive officer, told a conference call.
"Right now we think the vast majority of customers without electricity will be restored by end of day," he said, speaking from NERC's headquarters in Princeton, New Jersey.
Adding up the damage is a daunting and still incomplete task involving data collection from the dozens of utilities and hundreds of power plants that share the Northeast U.S. and Canadian power transmission grid.
"We're putting out numbers like we know how many (lost power), but we don't. We do know there were major, major outages," Gent said.
Gent estimated the blackout that struck shortly after 4 p.m. Eastern time Thursday affected about 50 million people living in an area extending from the Great Lakes to New England, including such major urban centers as Detroit, Cleveland, New York, Toronto and the Canadian capital of Ottawa.
"Overall, we think we lost ... about 10 percent of the entire Eastern Interconnection," he said, referring to the power grid that serves the eastern half of the United States and Canada.
Included in the outages list were about 100 power plants that "tripped" when circuit breakers, designed to protect costly electric gear from sudden voltage fluctuations, automatically shut them down.
Some of those plants can be switched back on quickly, but the big coal-fired and nuclear plants, for example, often take up to 48 hours to get back to full power, Gent said.
FOCUS ON GREAT LAKES LINES
The blackout raced across the vast network of high voltage lines that span the region. And it is these lines that have the attention of the engineers heading up the initial investigation, Gent said.
Gent said terrorism was quickly ruled out because the extensive operating logs kept at power plants, substations and switchyards showed no signs of equipment sabotage.
He also ruled out lightning hitting a line or the grid's inability to keep pace with energy demand, even though it was a hot, muggy afternoon and the blackout struck right when air conditioning would have been at its peak for the day. Both of these factors were fingered early on as possible culprits.
Warning that pinpointing the cause of the nation's biggest blackout might take months, Gent said "We're putting together a team of experts. We should have preliminary answers soon. I wish I could be more specific."
The federal Energy and Homeland Security Departments are being brought into the probe, which Gent said would also likely spawn a series of congressional hearings.
"I am personally embarrassed and upset that this happened," Gent said. "My job is to see that this doesn't happen, and you can say I've failed at my job."
9-10 SECOND EVENT
Gent said the entire "event" was first detected on lines in the Midwest and lasted no more than nine or 10 seconds, cascading through the electric system.
"The first event we have recorded was in the Midwest, but we're not sure that was the cause," Gent said.
"The Lake Erie Loop is the center of our focus. The path around Lake Erie and Lake Ontario has always been a big big problem. That'll turn out to be an issue here," he added.
The Lake Erie Loop is a series of connected lines that carry high voltage power roughly around the circumference of the lake, passing through key centers like Detroit, Cleveland and Toronto, all cities which felt the effects of the outage.
"We're still collecting the information. There were maybe a dozen or more transmission lines that relayed out, maybe 100 or more power plants that relayed out. We're still putting this together," he said.