After electricity demand soared during Tuesday's continuing bitter cold, one of the country's largest electric grid operators asked consumers in Illinois and several other states to turn down the thermostats a touch during peak usage hours Wednesday.

PJM Interconnection, which coordinates wholesale electricity distribution in 13 states including Illinois, is also asking residents to avoid using power-gulping appliances like the stove, dishwasher and washers and dryers between 6 a.m. and 9 a.m. and 3 p.m. and 7 p.m..

Demand in the PJM Interconnection’s territory reached about 141,500 megawatts Tuesday night, far above typical winter usage of 110,000 to 120,000 megawatts, a PJM spokeswoman said. Summertime peaks can reach 165,000 megawatts, the spokesman said.

Electricity use was expected to peak again Tuesday night and taper off as temperatures rise.

The last time the organization asked consumers to curb usage was in the summer of 2006 after several days of high temperatures, Paula DuPont-Kidd said. Such efforts can prevent more drastic measures like planned outages or voltage reductions.

"Of course we want people to be warm and not jeopardize their health," she said. "But if they can tolerate the thermostat to be a little lower than normal, every little bit like that reduces the amount of load on the system."

The cold weather has not led to significant outages or affected electrical lines in the Chicago area, a spokesman for Commonwealth Edison said.

Some commercial and industrial consumers that participate in a demand response program run by a company called EnerNOC were asked Tuesday to switch to alternative power sources such as generators for several hours.

Curtailing the load of electricity taken from the grid by dimming lights and shifting production loads to different times of the day helps balance supply and demand during times of high use, said Gregg Dixon, an EnerNOC spokesman.

The possibility of a large-scale power outage is low, officials said Tuesday. "But we want the public to be aware that … whatever they can do helps," DuPont-Kidd said. "It can make an impact if you have a large number of people making even small reductions."

mmanchir@tribune.com

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