On August 14, 2003, large portions of the Midwest and Northeast United States and Ontario, Canada, experienced an electric power blackout. The outage affected an area with an estimated 50 million people and 61,800 MW of electric load in the states of Ohio, Michigan, Pennsylvania, New York, Vermont, Massachusetts, Connecticut, New Jersey and the Canadian province of Ontario.
The incident started in Northeast Ohio and cascaded to its full extent in At 13:31 EDT, FE’s Eastlake 5 generation unit tripped and shut down automatically. Shortly after 14:14 EDT, the alarm and logging system in FE’s control room failed and was not restored until after the blackout. After 15:05 EDT, some of FE’s 345 kV transmission lines began tripping out because the lines were contacting overgrown trees within the lines’ right of way areas.
A series of line outages in Northeast Ohio starting at 15:05 EDT caused heavy loadings on parallel circuits, leading to the trip and lock-out of FE’s Sammis-Star 345 kV line at 16:05:57 EDT.
The blackout began a few minutes after 16:00 EDT, and power was not restored for four days in some parts of the United States. Parts of Ontario suffered rolling blackouts for more than a week before full power was restored.
Estimates of total costs in the United States range between US$4 billion and US$10 billion. In Canada, gross domestic product was down 0.7% in August, there was a net loss of 18.9 million work hours, and manufacturing shipments in Ontario were down C$2.3 billion.
Between 16:10:36 EDT and 16:13 EDT, thousands of events occurred on the grid, driven by physics and automatic equipment operations. When it was over, much of the Northeastern United States and the province of Ontario were in the dark.
By 16:13 EDT, more than 508 generating units at 265 power plants had been lost, and tens of millions of people in the United States and Canada were without electric power.