Under the Quality of Service Regulation, exceptional events are deemed to have all of the following characteristics:
-Low likelihood of the occurrence of the event or its consequences;
-They cause a significant reduction in the quality of service provided;
-it is not economically reasonable for the distribution system operator to avoid all their consequences;
-The event and its consequences are not attributable to the distribution grid operator.
An event shall only be regarded as an exceptional event after approval by the Energy Services Regulator following a well founded request by the distribution grid operator.