The study found that system average interruption duration index (SAIDI) has improved over the 2009 to 2014 year period by about 6 percent. The primary driver has been a reduction in the frequency of power outages.
Most regions of the U.S. saw improved performance over this period.
According to the study, 2011 was the worst year for reliability across the U.S. due to a number of severe storms that did not reach the exclusion definition for most utilities. There are regional variations in reliability, PA Consulting noted.
The Northeast, Plains and West regions have the strongest reliability performance. Mid-Atlantic region is most improved.
New York led by Con Edison and Rhode Island led by Narragansett have the best consistent state performance.
Some state utility commissions do not require public disclosure of utility reliability performance including Alaska, South Dakota, Wyoming, Tennessee, Alabama and South Carolina.