2 Sustained outage: power outage lasting longer than five minutes SYSTEM AVERAGE INTERRUPTION DURATION INDEX (SAIDI) Cumulative duration (in minutes) of sustained repair outages experienced by the average customer in a year1 CUSTOMER AVERAGE INTERRUPTION DURATION INDEX (CAIDI) Average repair outage duration (in minutes) per customer; also, average time to restore service1 SYSTEM AVERAGE INTERRUPTION FREQUENCY INDEX (SAIFI) Number of sustained repair outages2 experienced by the average customer in a year1 HOW WE’RE DOING We measure our reliability progress for unplanned outages, reporting it year-over-year.