Withering in a heat wave and wary of an unforgiving forecast, businesses across the Midwest turned off lights and computers and told workers to stay home Friday.

Utilities asked residents to take similar steps, such as turning down air conditioners and cutting back on appliance use until temperatures drop from the 90s. That's not expected until next week."When we go to the public and ask them to reduce their power, it's a major step," said Deb Strohmaier, spokeswoman for Columbus-based American Electric Power, which serves 7.5 million people in seven states.

Honda shut down production at its East Liberty plant Friday because there was no guarantee the automaker would have power throughout the day, spokesman Roger Lambert said. Production at Anna and Marysville continued.

LTV Steel in Cleveland ordered heat-related cutbacks for the first time in three years. In Lorain, USS/Kobe Steel Co. idled two bar mills and two oxygen plants.

"We're probably down more than half," company spokesman Tom Ferrall said.

American Electric Power, Akron-based FirstEnergy Corp. and Cinergy of Cincinnati asked customers Thursday not to use appliances such as ovens, dishwashers and washers until after 9 p.m.

Utilities in Michigan and Illinois also urged customers to limit their use of air conditioners.

As temperatures spiked Thursday afternoon to 96 degrees in Detroit - and held at 90 degrees as late as 11 p.m. - area hospitals began treating the season's first few cases of heat exhaustion.

"It usually takes two or three days into the heat wave before we start to see people drop," said Dr. Frank McGeorge of William Beaumont Hospital in Royal Oak. "It takes that long for people to get severely dehydrated."

Parts of Ohio already were recovering from severe thunderstorms Wednesday before the energy warnings were issued. The storms knocked the Davis-Besse nuclear power plant near Toledo off-line.

Meanwhile, Cleveland Mayor Michael R. White asked youngsters to stop opening fire hydrants to cool off. He said the city would install extra water-saving sprinklers on hydrants in neighborhoods not served by city pools.