The Nation: WHY THE LIGHTS WENT OUT

How could a power system that many people thought was made fail-safe after the Northeast's great 1965 blackout plunge New York City into helpless darkness once again? It may take months of investigation to get the complete answer. But at week's end, an outline of the falling-domino sequence of failures that led to the total collapse had begun to emerge.

Like other major utilities in the U.S. and Canada, New York's embattled Consolidated Edison Co. (see ECONOMY & BUSINESS) not only has its own electrical generating plants but is plugged into a larger regional pool of power producers. Depending on the electricity needs of its 9 million customers in New York City and neighboring Westchester County, Con Ed can either 1) rely largely on its own generators, or 2) buy power from neighboring utilities if the load—or demand from its users—is high, or 3) sell off surplus electricity to other companies. Yet those choices are complicated by another fact: electrical energy cannot economically be stored. Even a relatively small variation in load in one part of the system must be quickly compensated for elsewhere along the line. Indeed, the decisions of controllers to buy or sell electricity, or to switch in additional generators, require such split-second timing and are so complex that large utilities like Con Ed have increasingly computerized their operations.

On the night of the blackout, the New York metropolitan area was sweltering under a blanket of hot, humid air. With air conditioners whirring everywhere and electrical load high—though still far below the levels expected later this summer—Con Ed was importing from neighboring utilities about one-third of the electricity it was delivering to its customers. That in itself was not unusual. In the battle to keep its rates from soaring even higher. Con Ed has lately been buying more and more electricity from nearby companies that can provide cheaper power. Yet what made Con Ed especially vulnerable that soggy evening was a series of highly improbable natural events—"acts of God." as one spokesman called them.

A severe summer thunderstorm had just swept across the green suburban hills of northern Westchester in the vicinity of the Indian Point No. 3 nuclear power plant overlooking the Hudson River. At 8:37 p.m., according to Con Ed's preliminary analysis, flashes of lightning knocked out two 345-kilovolt lines. That immediately cut off all the electricity from the 900-megawatt Indian Point facility, and the nuclear plant was promptly and safely shut down. Then, while duty officers at Con Ed's main control center in Manhattan—a huge, display-filled room somewhat like Mission Control in Houston—scrambled to make up for the power loss, lightning struck again. At 8:56 p.m. bolts knocked out two more upstate 345-kilovolt lines in Westchester that bring in power from upstate New York and New England. Three minutes later, lightning knocked out yet another line. Worse still, circuit breakers designed to reset automatically after the enormous voltage surge caused by a lightning bolt apparently failed to close. By now the utility had suffered a massive loss of some 2,000 megawatts—more than a third of its electrical load that night.