City Hall Sues Con Edison Over 18-Hour Blackout
Giuliani administration sues Consolidated Edision, contending that blackouts in Washington Heights and other neighborhoods on July 6 and 7 were caused by utility's failure to properly design and maintain its network of cables that distribute electricity; does not ask for specific amount in damages, but Mayor Rudolph W Giuliani says he hopes to recoup 'multiple millions of dollars' for extra costs during power failures; photo (M)