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Measuring Reliability

Con Edison has a strong reputation for reliability. The company was named winner of the 2012 ReliabilityOne™ Award for the Northeast Region for Outstanding Reliability Performance by PA Consulting Group for the company’s electricity delivery in 2011. Con Edison also received an award for Best Overall System-Wide Reliability.

“These awards for reliability are very gratifying, especially with all of the challenges and the extraordinarily difficult circumstances we faced in 2012,” said John Miksad, Con Edison of New York’s senior vice president for Electric Operations. “With the hardships so many in our service area have faced with the onset and aftermath of Superstorm Sandy, this affords us only a moment before we redouble our efforts to further strengthen our systems against the possibility of unprecedented weather that our region just experienced. We remain committed to serving our customers going forward with the excellence symbolized by these honors.”

Two standard measures of electrical distribution service reliability are the System Average Interruption Frequency Index (SAIFI) and the Customer Average Interruption Duration Index (CAIDI).


SAIFI is compiled year by year, and the figure represents the total number of interruptions divided by the total number of customers served. The lower the value, the better the performance.

  2012 2011 2010 2009 2008
CECONY 0.102 0.147 0.129 0.104 0.126
O&R 0.97 0.96 1.15 1.07 1.22


CAIDI is also compiled year by year, and represents the average time to restore interrupted customers. It is calculated as the total customer-minutes of interruption divided by the total number of customers affected. Once again, the lower the figure, the better the performance.

  2012 2011 2010 2009 2008
CECONY 138.0 162.6 154.2 136.2 118.2
O&R 93.6 98.1 118.7 100.3 96.4