HOBOKEN, N.J. — For utility crews racing to restore power to residents of this waterfront city that have been sitting in the dark for a week, the task is both mundane and monumental: clean a bunch of gunk off electrical equipment with rags and cleaning spray.

That’s the way it has been across the Northeast, as crews clean, replace and fix the equipment needed to get the lights back on for millions of customers who lost power when Superstorm Sandy blew through.

In Hoboken, the salty, filthy floodwater of the Hudson River swamped a substation that relays power to 10,000 homes and businesses. It worked its way into switches and in between wires. It washed over the hunks of copper and silver capable of handling 26,000 volts of electricity. It fouled everything below a perfectly straight line of dirt on all the boxes of circuit breakers and transformers on site that marked the crest of the flood.

“It’s getting the crud off,” said Mike Fox, a Public Service Electric and Gas Co. engineer who was supervising the company’s substation restoration. “It’s nothing earth shaking, but it’s a lot of stuff.”

Sixty-seven thousand utility workers in the Northeast are working day and night on tasks they are familiar with: putting up telephone poles, stringing wire and replacing transformers. But Sandy’s storm surge added another dimension by attacking the utilities’ internal equipment. Switching stations, substations and underground electrical networks were inundated in Manhattan, Brooklyn, Hoboken and elsewhere.

But it’s the sheer volume of work that is making the power outages last so long. At the peak, 8.5 million homes and businesses were without power. A week after the storm walloped the Northeast, 1.4 million customers remained in the dark, mostly in New York and New Jersey. Getting the power back on for all of them will take at least another week.

Frustration is turning to anger and despair. The air in the region has a winter chill and another storm is approaching. Some without power see neighbors with twinkling chandeliers even as they still use candles.