This Indian Standard ( Part 1) which is identical with IEC 60664-1 (2002) 'Insulation coordination for equipment within low-voltage systems — Part 1:As IEC 60664-1 is a safety document there were attempts to deemphasise functional insulation in early drafts, resulting in manyremoval objections. Functional IEC 60664-1 Edition 3: Insulation coordination for equipment within low-voltage supply systems -. Part 1: Principles, requirements and tests. 1 This part of IEC 60664 deals with insulation coordination for equipment within low- voltage systems. It applies to equipment for use up to 2 000 m above sea This part of IEC 60664 deals with insulation coordination for equipment within low-voltage systems. It applies to equipment for use up to 2 000 m above sea IEC 60664-1:2020 deals with insulation coordination for equipment having a rated voltage up to AC 1 000 V or EN IEC 60664-1:2020 - BARVE na PDF-str 59. IEC Approach (as explained by Klaus Stimper). • Basis of tables in IEC 60664-1. • Literature study of more than 50 publications on transient overvoltages