Long Island Power Authority's much-hyped Neptune cable was activated Thursday.

LIPA CEO Richard Kessel threw the ceremonial switch and said, "This clearly is the most important energy project ever designed for Long Island."

The Neptune cable runs underground, connecting the power authority's New Cassel plant with Sayreville, New Jersey, 65 miles away. LIPA said 600,000 Long Island homes can be powered by the up to 660 megawatts made available by the cable.

Kessel said buying power from western and southern states is a third cheaper than the alternatives on the spot market, a claim former LILCO executive Matthew Cordaro disputes.

"LIPA has been unable to secure contracts, long-term or even short-term contracts, of significant amounts of nuclear and coal power," Cordaro said. He said LIPA is now looking at more costly power sources, meaning the Neptune cable could actually cause energy rates to increase per household.

Kessel said LIPA hopes to construct a second Atlantic power cable and complete the Caithness generating plant in the coming years.

Despite the extra jolt of power to Long Island, Kessel warned residents not to become lax when it comes to energy conservation.

"Don't waste energy," he said. "Don't take the message that the Neptune cable is on, you can relax."