An eight-day stretch without electricity has come to an end for most of the estimated 100,000 residents of northwest Queens, and thousands more were poised to get power again as Consolidated Edison crews worked through the night, moving from manhole to manhole to repair the damaged energy network.

Mayor Bloomberg, who said he is optimistic, called the progress significant. As of yesterday evening, about 92,000 people had seen their power restored.

Mr. Bloomberg said Con Ed promised him a preliminary report by August 2, describing what happened, and he said the city would “stay on the process” to keep Con Ed to its word for full disclosure to help prevent similar blackouts in other parts of the city.

“To find out exactly why it happened is going to take longer,” he said.

Asked whether he would press for an independent inquiry of the outages, the mayor said, “I never thought it’s a great idea to have anybody investigate themselves,” and added that he believes Con Ed would welcome an outside investigation if he saw it necessary. In the interest of time, however, Mr. Bloomberg said he would accept Con Ed’s self-investigation for now.

Some energy analysts aren’t waiting for the utility’s reports to answer the question of whether much of the current infrastructure could trigger a similar blackout.

“‘Yes’ is the simple answer,” a member of the mayor’s energy task force, Ashok Gupta, said.

A more significant question to ask, he said, is whether New York City is willing to invest vital upgrades to the energy matrix that could cost billions of dollars.

“State regulators need to sit down with the city and Con Ed and map out a strategy to really remake the distribution system so it isn’t under stress and failing when we face multiple hot weather days,” Mr. Gupta, who is also a director of the Natural Resources Defense Council, said.

Con Ed said northwest Queens lost power last Monday when temperatures in the 90s melted almost half the cables that feed electricity to the area.

The utility said it could have chosen to shut down power in a wider section of Long Island City for a briefer, controlled period, but decided instead to let the remaining feeder cables handle the load, which likely contributed to the failure.

Because of the setup of the network, Con Ed said it has been unable to count precisely how many New Yorkers have no power: The utility’s estimates are based on customers’ reports and worker tallies of lights on and off in windows as they go block to block, a spokesman for Con Ed, Alfonso Quiroz, said. This painstaking method — coupled with the fact that a “customer” can range from a single person to an entire building full of people — has complicated attempts to quantify the damage. Early estimates underreported the damage by a factor of 10.

Even as power comes on and people in the affected areas restock their refrigerators and begin to enjoy air-conditioning for the first time since July 17, the crisis generates political electricity.

Three elected officials from western Queens angrily demanded consequences Monday against Con Ed for the blackout.

“Every decision Con Ed has made has been the wrong one,” a City Council member who represents the area, Peter Vallone Jr., said after Mr. Bloomberg’s morning news conference. Mr. Vallone called for a federal monitor to oversee Con Ed.

Three politicians — City Council Member Eric Gioia, Assemblyman Michael Gianaris, and Mr. Vallone — renewed their demands that the Con Ed official who has presided over the outages, Kevin Burke, immediately resign as the utility’s chairman and CEO.

Mr. Burke, through a spokesman, said again that he wouldn’t do so.

Mr. Bloomberg also explained his decision not to seek a designation from the governor, as several Queens politicians have demanded, that northwest Queens be designated a disaster area.

“Federal monies typically come in when you have big damages done in terms of physical destruction, and that’s not the case here,” Mr. Bloomberg said.

While Mr. Bloomberg had been criticized for not getting more involved earlier, the city has deployed to northwest Queens hundreds of police officers, food inspectors, paramedics, and social workers — and even temporary stop signs to stand in for broken traffic lights. He said that “given the size of our budget,” the costs are relatively small and he hadn’t considered asking Con Ed to reimburse the city.

Governor Pataki said in a letter to Queens lawmakers that Con Ed, “not the taxpayers,” should bear the primary responsibility for the extra costs. While the mayor has been stalwart in his defense of Con Ed, the governor expressed “frustration and disappointment” with the utility.