Endeavor to Avoid Interruptions. Each utility shall make reasonable efforts to avoid interruptions of service, but when interruptions occur, service shall be re-established within the shortest time practicable, consistent with safety. Report to Commission. Each utility shall promptly report to the Commission's Engineering Division and Consumer Affairs Division: The onset of a major outage event; A sustained interruption, to firm-service customers, initiated by the utility in response to unacceptable system voltages; and A sustained interruption, to firm-service customers, initiated by the utility in response to thermal overloads of electric plant. The utility's report required by §B(1) of this regulation shall include a general description of the areas experiencing a sustained interruption and the expected system restoration times, if available. The utility making the report required by §B(1) of this regulation shall also provide periodic updates to the Consumer Affairs Division. Planned Interruptions. Planned interruptions shall be made at a time that will not cause unreasonable inconvenience to customers and shall be preceded, if feasible, by adequate notice to those who will be affected. Record of Interruptions. Each utility shall keep records of interruptions of service on its primary distribution system and shall make an analysis of the records for the purpose of determining steps to be taken to prevent recurrence of the interruptions. The records should include the following information concerning the interruptions: Cause; Date and time; and Duration. Momentary Interruption Record. A utility shall maintain information which it collects on momentary interruptions for 5 years. Unattended Substations. The record for each unattended substation shall show interruptions which required attention to restore service, with the estimated time of interruption.