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Northeast blackout of 2003

Power outage in North America

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Through Power outage and Watt

Most places restored power by midnight (within 7 hours), some as early as 6 p.m. on August 14 (within 2 hours), while the New York City Subway resumed limited services around 8 p.m. Full power was restored to New York City and parts of Toronto on August 16. At the time, it was the world's second most widespread blackout in history, after the 1999 Southern Brazil blackout. The outage, which was much more widespread than the Northeast blackout of 1965, affected an estimated 55 million people, including 10 million people in southern and central Ontario and 45 million people in eight U.S. states.

The blackout was due to a software bug in the alarm system at the control room of FirstEnergy, which rendered operators unaware of the need to redistribute load after overloaded transmission lines dropped in voltage. What should have been a manageable local blackout cascaded into the collapse of much of the Northeast regional electricity distribution system.

Immediate impact

According to the New York Independent System Operator (NYISO)—the ISO, responsible for managing the New York state power grid—a 3,500 megawatt power surge (towards Ontario) affected the transmission grid at 4:10:39 p.m. EDT.

For the next 30 minutes, until 4:40 p.m. EDT, outages were reported in parts of Michigan (Detroit), Ohio (Cleveland, Akron, Toledo), Ontario (Toronto, Hamilton, London, Windsor), New Jersey (Newark), and New York (New York City, Suffolk, Nassau, Westchester, Orange and Rockland counties, Rochester, Syracuse, Binghamton, Albany).

This was followed by outages in other areas initially unaffected, including all of New York City, portions of southern New York state, New Jersey, Vermont, Connecticut, as well as most of the province of Ontario. Eventually, a large, somewhat triangular area bounded by Lansing, Michigan, Sault Ste. Marie, Ontario, the shore of James Bay, Ottawa, New York, and Toledo was left without power.

According to the official analysis of the blackout prepared by the US and Canadian governments, more than 508 generating units at 265 power plants shut down during the outage. In the minutes before the event, the NYISO-managed power system was carrying 28,700 MW of load. At the height of the outage, the load had dropped to 5,716 MW, a loss of 80%.

Essential services remained in operation in some of these areas. In others, backup generation systems failed. Telephone networks generally remained operational, but the increased demand triggered by the blackout left some circuits overloaded. Water systems in several cities lost pressure, forcing boil-water advisories to be put into effect. Cellular service was interrupted as mobile networks were overloaded with the increase in volume of calls. Multiple cell sites were out of commission due to power outages. Television and radio stations remained on the air, with the help of backup generators, although some stations were knocked off the air for periods ranging from several hours to the length of the entire blackout.

High heat played a role in the initial event that triggered the wider power outage. Much of the affected region reached temperatures higher than 31 °C (88 °F) that day, increasing energy demand as people across the region turned on fans and air conditioning. This caused the power lines to sag as higher currents heated the lines.

Most of the Amtrak Northeast Corridor service was interrupted, as it relied on electricity for its signaling and crossing systems; electrified commuter railways also shut down. Via Rail in Canada was able to continue most of its service. All airports in the affected area closed immediately, there were no departures, and incoming flights had to be diverted to airports with power.

The reliability of the electrical grid was called into question and required substantial investment to repair its shortcomings.

In areas where power remained off after nightfall, the Milky Way and orbiting artificial satellites became visible to the naked eye in metropolitan areas where they cannot ordinarily be seen due to light pollution.

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