More than 4 million customers served by Con Edison, LIPA, PSEG, JCP&L, Connecticut Light and Power, Orange & Rockland, and NYSEG were without power as of late Tuesday night.
Power in Manhattan should be back by the end of the week, but the Bronx, Queens, Staten Island and Westchester County could be without electricity for far longer, Con Edison said.
Con Edison told WCBS 880 Tuesday evening that power would likely be back in Manhattan by the end of the week. Earlier estimates said Manhattan, as well as Brooklyn, should see their power back within as few as four days.
But outlying areas pose a greater challenge, a spokesman said.
"Obviously, more ones and twos when you're located out in the outlying areas, and you can do just as much work to restore those as you take to restore 10,000 people early on," said Con Edison spokesman Bob McGee.
"This is the largest storm-related outage in our history," said Con Edison Senior Vice President for Electric Operations John Miksad.
Sandy beat the previous record which was set last year when Hurricane Irene left more than 200,000 customers in the dark.
Crews are facing several challenges restoring service. Miksad said much of the low-lying areas of New York City and Westchester County remain underwater, 200 wires are down on Staten Island, and there are more than 180 roads closed in Westchester.
Con Ed's Relay Protection Room at its 14th Street facility shut down when the East River surged into the structure Monday, as superstorm Sandy pounded the region.
WCBS 880's Peter Haskell reports
The Relay Protection Room houses some very sensitive equipment that could take some time to get back on-line.
"First thing we have to do is remove the salt water which actually can be a very time-consuming process. We then have to inspect, clean, test and ensure the equipment is ready to be returned to service," John McAvoy with Con Ed told reporters, including WCBS 880's Peter Haskell on Tuesday.
Sandy proved to be worse than the worst-case scenario, McAvoy said.
"We designed our equipment to be over almost a foot and a half above the highest high tide ever seen before,"
McAvoy said this storm surge was more than two and a half feet higher than the previous record high tide.
McAvoy also said Con Ed did not preemptively shutdown the 14 networks that service the areas without power. He said the explosion that many people have seen video of turned out to be a circuit breaker.
But McAvoy insisted even if they had shut down the networks in advance, the results would have been the same.
"And so the restoration time for the large majority of this equipment would not have been any less if we had removed it from service pre-emptively," McAvoy said.
In Manhattan, power was knocked out around 8:30 p.m. Monday, leaving a huge stretch from East 39th Street to the lower tip in the dark.
It could take up to four days to restore power to about 6,500 customers affected by a planned power cut. Con Ed cut power intentionally to some customers in lower Manhattan and southern Brooklyn in an effort to protect equipment from salt water and allow for quicker restoration.
"We have to assess the damage," spokesman Chris Olert said. "Now we have to get in there, get the salt water out, basically the dried salt, dry the equipment, test it and then make sure it's safe to restore the power."
Con Ed is advising customers to assume downed electrical wires are live and not attempt to move or touch it with any object.
"Just stay indoors; stay safe," Olert said.
Customers can report downed power lines, outages, and check service restoration at www.conEd.com or by calling 1-800-75-CONED (1-800-752-6633).
Gov. Andrew Cuomo said Long Island took the brunt of the burden, with power being knocked out to nearly 930,000 customers, roughly 90 percent of the area's utility customers.
The Long Island Power Authority said it could take seven to 10 days to restore service. Crews have begun assessing the damage.
Over 2 million New Jersey households were without power as of Tuesday night. PSE&G's outage, which included between 1 and 1. 5 million customers, was the largest storm in the utility's history.
The utility said severe flooding from the storm surge affected substations in Essex, Hudson, Bergen, Union and Middlesex counties. The substations have been taken out of service and equipment will be cleaned and dried once the water recedes.
"We can get a lot of customers back at one time if we get the substations dried out, cleaned out, repaired as needed. And that we're hoping to do in the next day or so, for the most part," Johnson said. "Some of the other damage from the storm - downed limbs, tree limbs, wires - that will take a little bit longer. We are working on that as well. Unfortunately, some customers may be out for seven or more days."
Crews will also have to wait for strong winds to subside so it is safe to work in bucket trucks and other equipment. The utility is working with town and county officials to work on clearing roads of debris so crews can get to locations with damage.
"This is clearly the worst storm in our history," Johnson said.
"PSE&G will be working around the clock to assess the damage and restore service," PSE&G president Ralph LaRossa said.
PSE&G is urging customers to be ready for lengthy outages, lasting seven days or more.
To report a power outage call 1-800-436-PSEG.
Meanwhile Tuesday night, JCP&L was reporting 966,000 outages. Connecticut Light and Power had about 374,000 customers affected; Orange & Rockland was reporting 199,000 outages; NYSEG had about 109,000 outages.
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