Posted: Oct 30, 2012 10:45 AM by CNN
NEW YORK - Hurricane Sandy wreaked havoc on parts of the power grid Monday, knocking out power lines across the Northeast and forcing two nuclear power plants to shut down.
Some 7.5 million customers remain without power as of Tuesday morning, according to CNN estimates.
In Manhattan, a massive explosion at a ConEdison plant along the East River left a big chuck of the island in the dark.
Throughout the region, downed trees and flooding have taken out power lines that serve millions. Utilities say it could take 7 to 10 days to repair the damage, even with extra crews that have been brought in from other parts of the country.
A ConEdison spokesman called it "the worst damage in ConEdison history."
Much of ConEdison's power equipment is underground, including in subway tunnels. Those tunnels are now flooded, some with water all the way to the ceiling.
They are not expected to be drained for several days, New York Mayor Michael Bloomberg said at a press conference midday Tuesday.
On Long Island, nearly a million customers are without power, according to the Long Island Power Authority.
New York Gov. Andrew Cuomo, also speaking at a press conference, said that amounts to 90% of the customers on Long Island.
Unlike in Manhattan though -- where the underground flooding was unprecedented -- Cuomo said LIPA has had plenty of time and experience to prepare for such an event.
In New Jersey, utility PSE&G described '"walls of water" that flooded electric substations in coastal parts of the state.
Over a million customers are without power in New Jersey, and the utility said restoration will be "a slow, painstaking process."
Complicating restoration efforts is the size of the storm. Utilities have agreements with each other across the country to send spare workers in the event of storm. But with so many states impacted by Sandy, there aren't many spare workers available.