Note 1 to entry: It represents the loss of supply to one or several customers.

Note 2 to entry: Some standards define supply interruption as a state in which the voltage at the customer supply terminals is less than a given percentage of the declared voltage.

Note 3 to entry: Supply interruptions are sometimes categorized as prearranged (in which customers are informed in advance to allow for the execution of scheduled work on the system) or accidental (caused by permanent or transient faults, mostly related to external events, equipment failures, or interference).

Note 4 to entry: This entry was numbered 603-05-11 in IEC 60050-603:1986.