By Scott DiSavino
NEW YORK (Reuters) - Power grid operators in the Northeast on Friday said they have enough resources to meet high demand as consumers crank up air-conditioners during a brutal heatwave, but urged steps to conserve electricity.
The National Weather Service issued excessive heat warnings and watches for cities from the Midwest to the East Coast, with temperatures expected to top 100 degrees Fahrenheit (37.8 degrees Celsius) in many places.
Power companies across the region warned that heavy electricity demand could stress some power lines and generating facilities, possibly leaving some customers in the dark temporarily.
PJM, the biggest power grid in the United States, and the Midwest ISO, the second biggest, this week both broke peak usage records set in 2006 before the recession cut demand for electricity.
PJM, serving 58 million people in all or parts of 13 Mid-Atlantic and Midwest states and the District of Columbia, said consumers used a record 158,450 megawatts on Thursday, breaking the record of 158,258 MW set in August 2006.
"PJM and our members plan and prepare year-round to handle days like this to ensure a seamless power supply for the 58 million consumers in our region," said Michael Kormos, PJM senior vice president - Operations.
The Midwest ISO, which serves more than 40 million people in all or parts of 12 Midwest states and Manitoba in Canada, said consumers used a record 103,975 MW on Wednesday, breaking the old record of 103,246 MW set in July 2006.
In New York City, Consolidated Edison reduced voltage in a few neighborhoods due to failed equipment on Thursday night. Con Edison fixed the equipment and ended the brownouts Friday morning.
The mercury in New York City, the biggest metropolitan center in the United States, was expected to reach 99 degrees F with the humidity making it feel more like 112 degrees, according to weather forecaster AccuWeather.com.
Thunderstorms on Friday will break the heatwave in the Midwest, while the East Coast will have to wait until Sunday for temperatures to return to near-normal levels in the upper 80s and low 90s, AccuWeather said.
RECORDS UNLIKELY FRIDAY
PJM forecast power usage would peak at 157,300 MW on Friday, shy of the 158,450 MW record set on Thursday.
New York ISO, which operates the state's grid, forecast the peak would top 32,700 MW on Friday, which is lower than Thursday's high and less than the 33,939 MW peak record set in August 2006.
In New England, ISO New England forecast the peak would top 27,600 MW on Friday, which is higher than Thursday's peak but still below the 28,130 MW record set in August 2006.
One megawatt powers about 1,000 homes in the United States and Canada.
Several utilities, including New York's Con Edison, which could see record power usage on Friday, have asked customers to find ways conserve power to keep air-conditioners humming for everyone.
Con Edison and other power companies have also activated demand response programs, which pay customers to reduce usage during peak demand times when needed.
Customers can reduce power use by turning up the air-conditioner thermostat, turning off lights, elevators and other electrical equipment, and for those with backup generators on site, producing their own electricity.
(Reporting by Scott DiSavino; Editing by Dale Hudson and David Gregorio)