* Company still unable to estimate cost of damage but will be material
* About 775,000 customers still without power, down from 1.7 million at peak
* May take 7-10 days to restore full service
* PSEG shares fall 2 percent
Nov 1 (Reuters) - Public Service Enterprise Group Inc , the biggest utility in New Jersey, said superstorm Sandy had caused severe damage to its infrastructure and it expected its losses to be material.
About 775,000 PSEG customers were still without power on Thursday, down from about 1.7 million at the peak, PSEG Chief Executive Ralph Izzo said, adding that it would take seven to 10 days to fully restore service.
Towns along the New Jersey shore took much of the brunt of Sandy, which barreled through the U.S. Northeast on Monday night, flooding homes, washing away boardwalks and rupturing gas mains as well as crippling power supplies.
The U.S. Energy Department said on Thursday that about 4.7 million homes and businesses in 12 states still lacked power in the wake of the storm.
PSEG, whose shares were down 2 percent, said it was unable to estimate total losses from Sandy, which damaged transmission, distribution and generating systems and flooded a large number of substations along the Passaic, Raritan and Hudson rivers, causing the worst outage in the company's history.
``Probably the most significant damage we sustained was due to a tidal surge ... that hit the northern part of the territory, and uniquely did some damage to our transmission system and some of our switching stations,'' Izzo said in a call with investment analysts, where he also praised President Barack Obama.
``The President actually was willing to speak to a group of CEOs and me personally about what he could do to help us out. So all hands are on deck and everyone is pitching in,'' Izzo said.
PSEG, which has about 2.2 million electricity and 1.8 million gas customers, said it intended to seek recovery from its insurers for some of the damage.
Izzo said the company could not estimate the ultimate cost of the storm damage, but drew a comparison with Hurricane Irene which hit the same area last August.
``Irene had a 2 cents impact (per share) on operating and maintenance costs, with 3 cents of deferred costs,'' Izzo said.
``Now this storm is different in two major ways -- it is bigger ... (and) has a lot more transmission outage,'' he said.
Sandy appears to have easily caused twice or even three times the losses of Hurricane Irene, catastrophe forecasting companies said on Tuesday.
PSEG said it would seek to recover its storm-related costs from formula rates. The company's transmission facilities are regulated by the Federal Energy Regulatory Commission.
Exelon Corp, a power company that serves Illinois and Pennsylvania, played down the impact of Sandy on its operations, saying that as long as the weather was normal for the rest the year, its full-year adjusted operating earnings would be higher than its prior forecast.
PSEG said on Thursday its net income rose 18 percent to $347 million, or 68 cents per share, in the third quarter from $294 million, or 58 cents per share, a year earlier.
PSEG's shares were trading at $31.36 on the New York Stock Exchange. Exelon shares were down about 2.6 percent at $34.84.
PSEG filed a petition with the New Jersey Board of Public Utilities on Oct. 26 seeking authorization to defer recording some costs related to the restoration of its gas and electric distribution systems.