FROM THE TIMES DISPATCH, Richmond, Va. — The eastern United States cooked for another day yesterday as unrelenting heat again sent thermometers past 100 degrees, buckled roads, slowed trains, and pushed utilities toward the limit of the electrical grid’s capacity.

Scattered power outages affected customers — including some in Richmond — along the East Coast, and usage approached record levels.

Temperatures in New York City passed 100 yesterday for the second day in a row, the first back-to-back readings that high since 1999, the National Weather Service reported.

With people cranking up their air conditioners, Valley Forge, Pa.-based PJM Interconnection — which operates the largest electrical grid in the U.S. — instituted emergency procedures to conserve electricity. PJM’s grid covers about 51 million people in 13 states and the District of Columbia.

Northern Virginia Electric Cooperative in Manassas activated its load-management system, which turns off electric water heaters and cycles the air conditioners of about 46,500 subscribers.

Dominion Virginia Power asked about 25 commercial and industrial customers to curtail their service or switch to standby generators. Those customers are on special rate programs in which they receive a credit for reducing their electricity use when the utility requests.

Dominion Virginia Power subscribers were consuming a little more than 18,000 megawatts yesterday afternoon.

“We’re not anticipating setting a record,” company spokesman Jim Norvelle said. And, he noted, usage should be markedly less today, which is expected to be about 10 degrees cooler than yesterday.

On Tuesday, Dominion Virginia Power customers’ demand peaked at 18,983 megawatts. The company’s record demand was 19,688 megawatts on Aug. 8, 2007.

Dominion Virginia Power is the state’s largest electric utility with more than 2.3 million customers.  About 2,900 customers in the Lakeside area of Richmond lost power for a short time yesterday afternoon.  The outage affecting four circuits occurred when a transformer failed during maintenance, according to Dominion Virginia Power.

In the Washington area, nearly 1,000 customers were without power yesterday.

Transportation officials cut the speed of commuter trains in suburban Washington and New York when tracks got too hot. Extreme heat can cause welded rails to bend under pressure.

Amtrak trains in Virginia ran late yesterday as a result of reductions in operating speeds because of the heat. “We’re seeing delays of 15 to 30 minutes,” Amtrak spokeswoman Karina Romero said.

Dominion charges customers a higher rate during the high-demand summer months for electric consumption above 800 kilowatt-hours a month.

The bill for a typical residential customer using 1,000 kilowatt-hours a month during the June-September period is $102.16, the company said. During October through May, the same monthly bill is $96.46, or 5.6 percent less.

Richmond TimesDispatch Staff writer Peter Bacqué and The Associated Press contributed to this report.

If you are in the Richmond Virginia area and are experiencing problems with your home’s air conditioning unit, please call Marshall Mechanical for service.  Our HVAC service is available 24 hours a day, 7 days a week, 365 days a year at 804.323.0189.  Plus, we have a number of high energy efficient heating and cooling options for you if you’re looking to depend less on the grid, including geothermal and solar heating and cooling units.