Weeks after Consolidated Edison understated by more than 10 times the extent of a blackout in northwest Queens, the city says it has started taking matters into its own hands.

Unable to trust the utility’s estimates of power outages, city officials have implemented a new system under which teams of police, emergency, and fire workers are deployed to canvass areas and go door-to-door whenever there are 1,000 or more customers without power or reports of a significant outage.

Con Edison has acknowledged that its system for calculating the extent of the outage was inadequate. The utility now says that at least 25,000 customers — representing more than 100,000 people — were without electricity at the height of the blackout. For the first four days of the blackout, it had estimated that fewer than 2,000 customers were in the dark.

The units, called Power Outage Response Teams, have been dispatched seven times since the Queens blackout, the head of the Office of Emergency Management, Joseph Bruno, told a City Council hearing yesterday.

The teams were a part of the city’s response to a declared heat emergency earlier this month, but while Mayor Bloomberg said they were dispatched to assist the utility in counting customers without power, Mr. Bruno cast the initiative in a different light.

The new system, he said, would give city officials “an independent view” of a power crisis, instead of relying solely on Con Edison. “I’ve never seen Con Ed so far off with their numbers,” Mr. Bruno said.

Yesterday’s hearing was the second in a series the council is holding on the blackout. It focused on the city’s response. Lawmakers largely praised Mr. Bruno and, as they have done repeatedly over the last month, directed their ire at Con Edison. Council members Peter Vallone Jr. and Eric Gioia of Queens accused company leaders of lying to the public about the extent of the damage and outages, and suggested that Con Edison had understated the problem so it could maintain its reputation for reliability. Days of inaccurate information led to delays in the city’s response, they said.

While criticizing Con Edison’s system for calculating the number of customers without power, Mr. Bruno stopped short of attacking the utility. “I don’t know whether they’re lying or not,” he said.

In a statement, Con Edison said it was “reviewing its system for counting customer outages and is exploring new technologies to better assess outages. We will find a better way.”

Amid a heat wave that began Monday, July 17, Con Edison did not publicly acknowledge until Friday that 25,000 customers, and not merely 2,000, had lost power, and officials have not conclusively determined when the majority went off the grid. For days, the only way the utility had of knowing who had lost electricity was through customer phone calls until officials decided to send crews out into the night to count homes without lights.

City officials had an idea that the outage was much more extensive on Thursday, Mr. Bruno said, based on a spike in calls to 311 the day before. Still, he said he was pushing the city to improve 311 so that officials could get access to data in “real time” during an emergency such as a power outage.

Con Edison is also under increasing pressure from the state Public Service Commission, the regulatory agency that is investigating Con Ed’s handling of the blackout. The commission’s director of electricity and environment, James Gallagher, told the council yesterday that he was “skeptical” of information the utility was providing to the investigation. The initial probe could lead to a more formal inquiry in which Con Edison would be forced to demonstrate that it acted reasonably during the blackout or face penalties.

Mr. Gallagher did not say when the investigation would conclude.