A brand new $6 billion cable that was supposed to help power New York City during the blistering heat will likely be offline for the rest of the month, a predicament Gov. Kathy Hochul called "unacceptable."

No power has flowed through the 339-mile line for more than 10 days and Hydro-Quebec, a company wholly owned by the provincial government of Quebec, estimates repairs to take another two weeks. Crews are trying to replace a section of damaged underground cable on the Empire State side.

“The Champlain Hudson Power Express project remains off-line,” said Peter Rose, a spokesperson for Hydro-Quebec. "Teams working around the clock have identified a fault with the terrestrial cable at a location on the U.S. portion of the transmission line route.”

The new details on the power failure emerged in the midst of a heatwave and when New York’s energy grid could use a boost. According to ConEd, the Champlain Hudson Power Express is the largest power source flowing into the city. The utility company is able to manage without it, but the line is a major component of its strategy for handling any increases in demand this summer.

Earlier this year, the New York Independent System Operator said it would have a particularly slim cushion of power to address peak demand over the summer. The situation is a result of higher demand and the retirement of older power sources.

For more than a week, Hydro-Quebec said it didn’t know what the problem was.

This is the second time this month the transmission lines have failed. In June, Gov. Kathy Hochul attended a ribbon cutting of sorts for the mostly subterranean line, touting it as one of the state’s largest contributions to its renewable energy supply. She called the project a massive victory for the state’s energy grid and climate goals.

The Hochul administration said it has been monitoring the outage.

“The ongoing CHPE outage is unacceptable, and at the governor’s direction, administration officials have been in daily contact with the developers as they work to identify and resolve the problem,” said Ken Lovett, senior communications advisor on energy and environment for Hochul. “The Champlain Hudson Power Express will play a key role in the state’s all-of-the-above strategy to keep the lights on and costs down for New Yorkers and ensuring its reliable operation must remain a priority.”

The line was largely inactive in June because of a contract issue. Hydro-Quebec said at the time that in July, the line would be up and running. So far this month, power has flowed through the lines for about three days.

”This is a very unusual outcome for a competent utility,” said Robert McCullough, principal of McCullough Research, an energy consulting firm. “ When something like this happens, the engineers from the vendor show up immediately.”

The first failure was attributed to a technical failure on the Canadian end of operations.

The international power lines bring 1.25 gigawatts of energy, roughly the capacity of a commercial nuclear reactor or enough electricity for 1 million households. Under the 25-year contract, the Canadian company is supposed to provide power May through October.

The line connects the Big Apple to a network of 61 hydroelectric plants in Canada.

This story has been updated with additional reporting.

CORRECTION: This story has been updated to fix the ownership of energy firm Hydro-Quebec. It is owned by the provincial government of Quebec.