Cause of Boston blackout in March remains unsolved
BOSTON—An independent engineering consultant hired by
Some customers were without power for days.
The 220-page report by RTI Group ruled out human error because no one entered or left the substation in the 18 hours before the fire.
A connection failed and sparked mineral oil, used as a cooling agent and conductor in the power line. But the root cause, the failure in a high-voltage connection, may never be solved.
An NStar spokesman tells The Boston Globe ( http://b.globe.com/M8dxza) the utility will follow up on recommendations in the report.
City and state officials say they are still reviewing the report.
Information from: The Boston Globe, http://www.boston.com/globe