The nation’s first large-scale offshore wind farm is taking shape, both at sea and on land.

On Tuesday, workers for Vineyard Wind pulled the second of two cables ashore through a conduit under Covell’s Beach in Barnstable.

“It might seem like [it’s] not the biggest deal, but it is connecting onshore with offshore for the first time in American history,” CEO Klaus Moeller said. “So we are very happy about those milestones.”

Vineyard Wind, with 62 turbines, will be the first offshore wind farm to generate as much electricity as a commercial power plant. Two small wind farms are already operating off the coasts of Rhode Island and Virginia with a combined seven turbines.

Vineyard Wind’s second cable, wider than a human hand and weighing about 70 pounds per foot, was pulled through the conduit into a trench about six feet deep at the back of Covell's Beach.

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The project's two undersea cables have three sections each: near shore, mid shore, and offshore. Both offshore sections and one near-shore section have been finished to date.

Five miles inland, the company’s electrical substation is approaching 70 percent complete, according to project staff. The seven-acre substation is near the Route 6 visitor’s center in Barnstable.

The substation will lower the voltage coming from the wind farm before the electricity enters the grid.

The voltage starts out higher — at 230 kilovolts — because transporting high-voltage power is more efficient, said Ian Campbell, senior environmental permit and compliance manager for Vineyard Wind.

Transformers will reduce the kilovolts to 115, and the power will pass through additional equipment to be “cleaned up,” meaning to eliminate spikes and dips in voltage.

The power will enter the grid at the adjacent Eversource substation.

Although Vineyard Wind is on track to begin generating power in the fourth quarter of 2023, Moeller said some of the turbines will be installed next year. He anticipates at least half will be ready for the initial opening, he said.

Vineyard Wind will have the capacity to generate 804 megawatts of energy, enough to power 400,000 homes.

An offshore wind project with a New York contract, South Fork Wind, also anticipates opening by the end of the year.