Historical
IEC 60721-3-4 Ed. 2.0 b:1995
Classification of environmental conditions - Part 3: Classification of groups of environmental parameters and their severities - Section 4: Stationary use at non-weatherprotected locations
Classifies groups of environmental parameters and the severities to which a product may be exposed under use conditions, including periods of erection work, downtime, maintenance and repair, when mounted for stationary use at locations which are non-weatherprotected.
International Electrotechnical Commission [iec]