NEW YORK - As the temperature soared near triple digits for a third straight day, the power grid groaned as New Yorkers used a near-record 12,987 megawatts of juice.

The city teetered on the brink of a massive power crisis yesterday as a crippling heat wave forced brownouts and scattered power failures from the East Side to the Bronx Zoo.

Seven feeder cables that pump electricity to large swaths of midtown Manhattan failed, prompting Con Edison to order businesses to reduce power use - or close down altogether.

"We just need to make an extra effort to conserve energy," said Mayor Bloomberg, who pleaded with New Yorkers to cut back on power use. "It ain't over till it's over."

The third day of a sweltering heat wave also knocked out lights, elevators and air conditioning in neighborhoods from Park Slope to Astoria.

Even the Bronx Zoo had to close its doors at 3 p.m. when it was hit by a brownout - and the medical examiner's office had to switch to emergency power to keep the corpses cool.

The worst-hit area was the Kips Bay section of the East Side, where Con Ed supervisors went door-to-door ordering businesses to turn down the air conditioning and dim the lights.

Police vans cruised the neighborhood with loudspeakers asking people to save energy.

"We can't work at all," said Jay Kim, 26, who works at a dry cleaner on Third Ave. "My boss is losing money every hour."

"Closed today," read a sign taped to the window of the Waterfront Ale House on Second Ave. "Thanks Con Ed."

Plenty of people packed it in and headed home early, like Michael Lane, who sipped on a Guinness at a local cafe after shutting down his publishing office on Park Ave. South.

"We just closed the office," said Lane, 38. "It gets hot very quickly in there."

By late in the afternoon, feeder cables were back online and some of the businesses were allowed to crank back up the cool air.

"We told and asked some customers to conserve power," said Chris Olert, a Con Edison spokesman. "By their conservation, we were able to get power back up."

A high of 6,600 customers, or about 25,000 people were without power yesterday morning, but by late afternoon the total was down to about 2,500 customers, or 10,000 or more people.

Julie Kim fed melting ice cubes to her panting dog Ziggy after her apartment near Union Square went dark and hot.

Like others, she was hoping the brownout would be over in a matter of hours, unlike the weeklong power outage that hit western Queens last month.

"You have to roll with the punches," said Kim, 30, a law student. "It could be worse. It could be like Queens."

The good news was that a round of heavy thunderstorms rolled through to finally break the back of the heat wave last night.

Temperatures that topped out at near 100 yesterday are expected to be in the seasonable high 80s, and even cooler air was expected for the weekend.

"The finish line is in sight," the mayor said.

Even so, the city apparently recorded its first death of the heat wave, although officials said alcohol abuse also may have contributed to the death of a Brooklyn homeless man.

Health Commissioner Tom Frieden said the city also would examine several other deaths to see if the heat contributed to them.

The city Emergency Medical Service had the sixth-busiest day in its history, responding to 4,063 calls, many of them related to the heat.

There were 425,000 people at the city beaches, and water consumption increased by 300 million gallons from the average as New Yorkers tried to drown their sorrows with cooling showers.

One unexpected benefit of the stifling heat was a decline in crime.

Police Commissioner Raymond Kelly surmised that criminals might be deterred by residents sitting outside on sultry nights, but the mayor had a different idea.

"Maybe the bad guys just don't go out when it gets hot," Bloomberg said.