General Order 166 standards apply to unplanned outages caused by damage to distribution or transmission lines or substations due to events such as storms, fires, accidents or terrorism. In contrast, planned outages also called rotating outages are created by system operators on rare occasion to reduce demand to prevent uncontrolled spread of outages when power supply is inadequate. See next section under Electric Emergency Action Plans (EEAPs).
In 1998, the Commission signed D.98-07-097, adopting General Order 166. The General Order (GO) comprises standards for operation, reliability, and safety during emergencies and disasters. The purpose of these standards is to insure that jurisdictional electric utilities are prepared for emergencies and disasters in order to minimize damage and inconvenience to the public which may occur as a result of electric system failures, major outages, or hazards posed by damage to electric distribution facilities. Jurisdictional electric utilities are required to file an annual report every October 31. These reports are on file at the Commission for public inspection.
Subsequently, in the year 2000, the Commission adopted D.00-05-022 adding Standards 12 and 13 to GO 166, pertaining to the Restoration Performance Benchmark for a Measured Event. A Measured Event is a Major Outage, resulting from non-earthquake, weather-related causes, affecting between 10% (simultaneous) and 40% (cumulative) of a utility's electric customer base. Standard 12 measures CAIDI (Customer Average Interruption Duration Index). CAIDI is defined as the total customer interruption duration divided by the total number of customers interrupted. CAIDI represents the average time required to restore service to affected customers.
Standard 12 states the Commission will perform a review of utility performance following every Major Outage and sets a benchmark for the Commission to use in reviewing utility restoration performance only during Measured Events. Standard 12's benchmark states that a utility's restoration performance during a Measured Event shall be presumed reasonable if the Customer Average Interruption Duration Index (CAIDI) is 570 or below, and presumed unreasonable if the CAIDI is above 570.
Customer minutes of interruption caused by outages of transmission facilities owned by the utility during a Measured Event are included in the calculation of CAIDI for purposes of this standard. However, not included are the customer minutes of interruption attributable to utility compliance with ISO directives, including its protocols, tariffs, transmission agreements or other written or verbal instructions specific to the event, which prevent the utility from restoring service it is otherwise able to provide.
Standard 13 sets a Commission benchmark for utility call center performance during Measured Events. A utility's call center performance is presumed reasonable if the percent busies calculation is lower than Level-1, and presumed unreasonable if above Level-2. Level -1 is defined as 30% busies over the day of the outage. Level -2 is defined as 50% busies over the day of the outage plus at least 50% busies in each of six one-hour increments (these increments need not be consecutive).
Utilities with fewer than 150,000 electric customers are exempted from application of Standards 12 and 13. Currently, Pacificorp, Bear Valley, Mountain Utilities, and Sierra Pacific are exempt from these standards.
Planned Outages Remain on Standby
Regulatory action since the power crisis of 2000-01 has kept power supply and demand in balance, but plans for rotating outages remain on standby in case conditions develop outside operator control.
The plans remain for controlled outages of geographical groups or blocks, to be implemented by local utilities as a last resort if the California Independent System Operator (CAISO) must announce a Stage 3 curtailment of demand in order to avoid more costly and widespread outages. The CAISO called several dozen Stage 3 events during the power crisis. See the CAISO's Stages of Electrical Emergencies.
For more information on Commission plans, please see Electric Emergency Action Plans (EEAPs).