Overall, the electrical grid covering the heat-afflicted East Coast and Midwest has handled power demands. The grid can manage usage as much as 15% higher than the expected "peak" demand, says John Moura of the North American Electric Reliability Corp., a group that monitors the grid.
Because of the economy, Moura adds, peak summer power demand nationwide is down about 35 gigawatts, a 4% drop from industry estimates made in 2008.
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"The worst part of this heat wave is that lows at night will only drop into the 80s due to the extremely high humidity," says AccuWeather meteorologist Henry Margusity. "This means there will be no time for people to cool off."
Nor will there be time for pole-mounted transformers to cool. In 2006's record year for power demands, for example, Sacramento weathered 11 days of 110-degree temperature, causing transformers in Northern California to burst into flames.
http://www.usatoday.com/weather/news/extremes/2011-07-21-east-coast-power-grid-heat-electricity_n.htm