* Outages approach Hurricane Irene levels
* Explosion at Con Edison Manhattan power station
* Around 25 percent of NYC customers without power
* New Jersey hardest hit state-DOE
NEW YORK, Oct 30 (Reuters) - More than 8.1 million U.S. homes and businesses were without power on Tuesday after Hurricane Sandy tore down power lines, flooded electrical networks and sparked an explosion at a Consolidated Edison substation on Manhattan's East River.
About a quarter of New York City's homes and businesses were without power 15 hours after Hurricane Sandy roared ashore accompanied by a nearly 14-foot (4.2-metre) tidal surge that flooded empty subway and highway tunnels.
Con Edison warned parts of New York City would be without power for a more than a week. Mayor Michael Bloomberg told a news conference the subway would be unlikely to resume service for four-to-five days.
Power providers reported outages in every state from North Carolina to the Canadian border and as far inland as Ohio and Indiana. New Jersey was hardest hit state with 62 percent of customers suffering blackouts. Seven states had a fifth or more of all customers without power.
At 11:00 a.m. EDT (1500 GMT), total U.S. outages were above 8.1 million according to the the Department of Energy, and were approaching the 8.4 million peak seen during Hurricane Irene last year.
The figures cover homes and businesses, meaning the total number of people affected will be far higher.
``This is the largest storm-related outage in our history,'' said John Miksad, Con Edison's senior vice president for electric operations.
An explosion at a substation on Manhattan's East River on Monday night contributed to the power cuts, and could complicate efforts to restore electric supplies. Large sections of the island below 39th Street - just south of Times Square - are without power.
Con Edison told customers via Twitter that the hardest hit areas may face more than a week without power. A total of 787,000 homes and businesses were without power in New York City and Westchester as a whole, out of a total of 3 million Con Edison customers.
NEW JERSEY SLAMMED
In New Jersey, 62 percent of homes were without power, according to the DOE. New Jersey utility Public Service Electric and Gas (PSE&G) said in a tweet that it was the ``largest storm in PSE&G history.'' The company asked customers to be patient as ``unprecedented'' flooding threatened to leave homes without power for days.
Pennsylvania, Rhode Island, New Hampshire, West Virginia, New York, New Jersey, and Connecticut all had statewide outages affecting 20 percent or more of customers, according to the DOE.
One forecasting company predicted economic losses could ultimately reach $20 billion nationwide, only half insured.
The state-owned Long Island Power Authority (LIPA) was one of the hardest hit utilities, with 85 percent of its 1.1 million customers in New York without power. It said it could take as long as seven to 10 days to return power to every customer.
Connecticut Light and Power's website said 38 percent of its customers were without power.
Power providers emphasized that customers must stay away from downed power lines. One woman in New York City was killed after stepping into an electrified puddle.