The Great Northeast Blackout of 1965
 
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It was evening rush hour on November 9, 1965. The power lines from Niagra Falls to New York City were operating near their maximum capacity. At about 5:15 a transmission line relay failed. Now there was insufficient line capacity for New York City. New England and New York are inter-connected on a power grid, and the power that had been flowing toward New York City had to go elswhere, instantly. The grid wan't prepared to handle this overload. Normally, this kind of minute to minute adaptation of the grid is a matter of adjusting to excess demand, not excess supply. When one power company has insufficient generating capacity it draws power from the grid. If the current load increases on the grid, the voltage begins to decline. In response, companies with additional capacity crank up their generators to push the voltage back up. On this evening in 1965 there was insufficient capacity to make up the current turned off by the blown relay in one part of the grid. Elsewhere (mainly in Ontario) parts of the grid were overloaded by the current diverted northward, leading generator operators to trigger shutdowns to protect their equipment. Almost the entire grid failed. A very few small power companies disconnected from the grid and kept operating independently. Other grids to which New England was connected, disconnected from the New England grid, leaving it on its own.  
 
The operators of the control centers at Consolidated Edison in New York and at Boston Edison, and in many other localities around New England , were left with a massive power shortage. But they had no contingency plan for partial blackouts to supply power to part of their customer base. One by one they were forced to shut down their generators to prevent damage from overworking them. The lights went out. The flickering decline took only a few minutes. New Hampshire, Vermont, Massachusetts, Connecticut, Rhode Island, New York, metropolitan New York City and some small parts of Pennsylvania were in the dark.
 
Then came the chaos of whether there was emergency power for critical services. Many of the emergency generators didn't work. The great New York airports had no runway lights. Consolidated Edison had generators whose bearings burned out because lubrication of the still spinning, massive turbines depended on electric pumps, powered by the grid. People were trapped in tall buildings by nonfunctional electric elevators. Street traffic was chaotic without traffic lights. It was a long night in the dark. Unraveling the outage problem took hours to days depending on locality. As a result of this disaster, a great deal of serious planning was done to prevent it from occurring again. Not that a power failure cannot happen, but controls were developed so that one failure cannot propagate to shut down an interstate grid. Sanity dictates that if there is a serious outage, only enough area should be blacked out so that the rest of the grid can continue in service. In addition, every emergency service reviewed its emergency lighting systems. Additional backup systems were installed. And regular testing of emergency backup systems was instituted.  
 
C. D. Sigwart 3-21-00  
(Who was on his way to supper in Cambridge , Mass. when the blackout started in 1965)