A weekend fire at the Connecticut end of the Cross-Sound Cable has knocked out service from the 24-mile line and repairs could take at least a month.
PSEG Long Island said the outage was caused by a fire in a transformer at a New Haven converter station last Saturday night. The cause of the blaze, which lasted several hours and temporarily shut down Interstate 95, remains under investigation, PSEG said.
The Cross-Sound Cable provides 330 megawatts of electric capacity to Long Island from various New England power sources, with a connection at Shoreham. It went online in 2003. LIPA has a 20-year, $330 million contract to purchase power through the cable, which ends in 2022.
Representatives from Cross-Sound Cable Co. didn't respond to calls seeking comment.
PSEG spokesman Jeff Weir said loss of power from the line won't affect Long Islanders, as there is ample energy from other on- and off-Island power sources.
"Power on the Island is stable," he said. "All contingencies have been considered. Our customers will not have any issues."
LIPA has around 6,000 megawatts of capacity from on-Island plants, other cables and renewables but rarely uses anywhere near that amount.
Friday afternoon, the Island's energy usage barely topped 2,500 megawatts, according to data from the New York Independent System Operator, which overseas state markets.
Weir said the NYISO expects repairs on the cable to be completed by Nov. 30.
Underwater power cables to Long Island have a recent history of problems.
In January, a New York Power Authority-owned cable under contract to LIPA from Westchester to East Garden City was knocked offline after it was damaged by an oil barge's anchor.
The 26-mile, 693-megawatt line, called the Long Island Sound Transmission Cable, was returned to service in July. NYPA, which was able supply power through backup lines, filed suit against the barge company to recover the $34 million repair costs.
In early 2012, the 660-megawatt Neptune cable was out of service for more than a year after two transformers failed on the Long Island end of the line in New Cassel.
LIPA paid upward of $40 million to replace the transformers and another $2 million to $3 million more a month in backup power costs during the 15-month outage.
LIPA has a 20-year, $1.75 billion contract for the Neptune cable.