A 26-mile electric cable to Long Island from Westchester County has failed for the second time in three months, limiting access to a large power supply as the summer peak season reaches its height.

The malfunctioning Long Island Sound Transmission Cable, owned by the New York Power Authority, connects from a Long Island Power Authority facility in East Garden City under Hempstead Harbor and the Long Island Sound to a Con Edison connection station in Yonkers.

It’s the fourth failure in the past two years. The 600-megawatt cable also failed in May, with service restored in July.

Utility officials said Long Island has adequate excess power from other sources to handle the loss.

The power line is a system of four different cables and has a backup that can provide for a reduced amount of power in case of failure. Officials couldn’t say whether the backup was operational, or when power would be restored.

advertisement | advertise on newsday

The latest outage, which began last week, occurred four miles from the East Garden City substation, NYPA spokesman Steven Gosset said, adding that, “As of now, there are no service issues or [an estimate of] when the cable will be back online.”

PSEG Long Island, which manages the local electric grid under contract to LIPA, is working with NYPA to repair the fault, which it said is in underground equipment on Roslyn Road near the intersection of Strawberry Lane in Roslyn Heights.

While there’s “more than enough capacity” to meet demand, PSEG spokesman Jeff Weir said the company is “eager to restore service to this line.”

The line experienced an outage in 2014 when an oil barge and tug dropped anchor in the area and damaged the cable, knocking it out of service for months, and causing $35 million in damage, NYPA said. The cable also failed on land in 2015.

Long Island is fed by four additional undersea power cables: the 660-megawatt Neptune Cable under the Atlantic, the 330-megawatt Cross Sound Cable under the Long Island Sound, a 428-megawatt Long Island Sound cable, and the 600-megawatt Y-50 Cable operated by Con Edison and LIPA. A megawatt powers 800 to 1,000 homes.