(a) For purposes of this section, the following definitions shall apply:

1. (1) “Customer average interruption duration index (CAIDI)” means the average interruption duration or average time to restore service per interrupted customer and shall be presented as the following ratio: Total sum of customer interruption durations/total number of customer interruptions;
2. (2) “System average interruption frequency index (SAIFI)” means the average number of interruptions per customer and shall be presented in the following ratio: Total number of customer interruptions/average number of customers served;
3. (3) “System average interruption duration index (SAIDI)” means the average duration of customer interruptions and shall be presented as the following calculation: SAIDI = CAIDI x SAIFI;
4. (4) “CIII” means the average number of customers without power per interruption index as determined by dividing the number of customers interrupted by the number of interruptions;
5. (5) “TMED” means the threshold value used to determine a major event day as defined in IEEE 1366-2022, Section 1.5 “Guide for Electric Power Distribution Reliability Indices,” dated 11/22/2022, available as noted in Appendix B; and
6. (6) “Major event day” means a day during which a utility’s daily system SAIDI exceeds the TMED.

(c) Each utility shall report the indices separately:

1. (1) With all interruptions included in the data; and
2. (2) With major event days excluded from the data.