An exasperated Cambridge has already taken over responsibility for its street lights from power company Nstar. Now, in part because of a recent eruption of power outages, the city is looking into going the whole way — buying back Cambridge Electric Light from Nstar and handling all of its own power needs.

“We had great customer service,” Mayor Michael Sullivan said, but when Nstar took over, “they did not invest in the infrastructure of the community.”

“They took the money and ran,” he said.

The city reclaimed the street lights in March after complaints that Nstar was slow to fix broken lamps. The increase in outages is new.

City electrician George Fernandes estimated there had been six or seven city outages in October, with the same expected for November. Some are mere blips — a second of blackness — but they reset clocks and alarms, disrupt computer networks and lose computer files all the same. And some outages can go for up to six hours.

Many of these are planned so Nstar can upgrade equipment, Fernandes said, and people whose power will be interrupted are supposed to be warned by the power company, by mail if there’s a lot of time or by telephone if there’s little. This doesn’t always happen.

“I’ve experienced it myself. I’m a resident of Cambridge,” Fernandes said, recalling recent work done by Nstar that resulted in a power outage. “My street was not [supposed to be] included, but my power went out. My wife said, ‘Did you know about this?’”

Storms can also take out power, and Nstar spokesman Michael Durand noted there had been many lately, including some with winds of more than 50 mph.

“We had two storms over the past two weeks. There was wind and rain and snow over the weekend,” Durand said. “We’ve had more than our region’s share of bad weather.”

In anticipation of winter snowstorms, the company is working with the city to identify tree limbs to trim back from six miles of power lines. And many of the planned outages, in which power is switched from one set of circuits to another, are necessary to boost the power coming out of the company’s Kendall substation to meet the demand of an increasingly device-driven society.

The upgrades are expected to be in place by 2006, he said.

That’s of little comfort to people whose power is disrupted several times over the course of a month — even if it’s scheduled at night, as Nstar tries to do — and the city hears the complaints as much as the company does.

“I get a thousand calls a day,” said one exasperated employee of the Department of Public Works.

Referring to Nstar workers, the employee said, “They’re idiots.”

Fernandes takes a more charitable view, noting that the company has some 41 communities to watch over. Before Cambridge Electric Light was merged into Nstar in 1999, the city had dedicated workers keeping a watch on city power.

That could happen again with a buyback of Cambridge Electric that remains within Nstar, but no time soon, and for no little amount of money. The first step is a feasibility study that itself could cost quite a bit.

“This would take several months of study,” said Ini Tomeu, speaking for city manager Robert Healy. “We don’t want to expend a huge amount of public funds until we’re able to analyze this further.”

Rick Guinness contributed to this report.