The current issue of this Standard is a revision of the previous issue C62.1-1957 to change many of the definitions, to add a new definition titled "Virtual Duration of Wave Front" which changes the method of measuring time to crest value, to eliminate the word "type" from arrester classification designations as superfluous, to add a 10 kv distribution arrester and 90 kv intermediate and station arresters to the list of standard ratings, to change the standard ratings above 90 kv to multiples of 3, 6, and 12 kv, and to make many editorial changes for purposes of clarification or conciseness.

This Standard applies to lightning protective devices designed to limit repeatedly voltage surges on 50 or 60 cycle per second power circuits by passing surge discharge current and subsequently automatically interrupting the flow of follow current. This Standard applies to devices for separate mounting and to those supplied integrally with other equipment