UPDATE 4-Heatwave causes New York brownouts as power use spikes
* Latest voltage reduction affects 97,000 customers
* New York ISO could break power use record Friday (Updates with Manhattan, Staten Island brownout)
NEW YORK, July 22 (Reuters) - A brutal heatwave is causing brownouts as homes and businesses in New York City and Westchester County crank up their air conditioners, likely pushing New York power usage to a new all-time record on Friday.
Initial data on the website of the New York state grid operator indicated power consumption may reach New York's all-time peak-hour record of 33,939 megawatts set in 2006.
Power companies across the U.S. Northeast, including Consolidated Edison (ED.N), said they had enough electricity to meet the demand, but warned heavy usage would stress some power lines and generating facilities, which could leave some customers in the dark temporarily.
That is what happened in the New York City area to Con Edison's 3.2 million customers.
The company had to reduce voltage on some equipment, called a brownout, for more than 100,000 customers in neighborhoods in Westchester and Queens overnight, followed by 37,000 customers in Manhattan and 60,000 customers on Staten Island Friday afternoon.
The company reduced the voltage in both areas as a precaution to protect equipment and maintain service as crews work to repair the problem.
Customers do not lose power in a voltage reduction. Many customers do not notice a voltage reduction which primarily affects things like incandescent lights, hot water heaters and some motors.
However, Con Edison reported scattered outages of up to 10,000 customers Friday afternoon, up from 7,600 earlier in the day.
The U.S. National Weather Service issued an excessive heat warning until 10 p.m. Eastern time for the New York City area.
Temperatures in New York will reach 99 Fahrenheit (37 Celsius) on Friday with the humidity making it feel more like 112 F, according to weather forecaster AccuWeather.com.
The heatwave will not break until Sunday when the mercury returns to more normal levels in the 80s and low 90s F.
Con Edison said usage peaked at 12,710 megawatts on Thursday. That was shy of the all-time record of 13,141 MW set in August 2006 before the economic recession weakened demand.
The company said demand could top the record Friday.
U.S./Canada peak power demand records [ID:nN1E76L08Q]
Con Ed meets NYC demand, imposes brownouts [ID:nN1E76L02T]
Massive heatwave spreads across U.S. [ID:nN1E76K1JV]
U.S. Midwest breaks power usage record [ID:nN1E76K0LQ]
During the voltage reduction, Con Edison asked customers in the affected areas not to use appliances such as washers, dryers, air conditioners and other energy-intensive equipment and to turn off lights and televisions when not needed.
Con Edison urged all consumers to conserve power to help keep the lights on and air conditioners humming.
Con Edison and other energy service providers in the state and across the U.S. Northeast activated some of their demand response programs, which pay consumers to reduce power usage during peak times when needed.
Customers can reduce power usage 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 and Eileen O'Grady in Houston; Editing by Alden Bentley)