This part of IEC 60721 classifies groups of environmental parameters and their severities to which products are subjected when installed for stationary use at non-weatherprotected locations. Weatherprotected locations where products can be mounted for stationary use permanently or temporarily are addressed in IEC 60721‑3‑3.

The environmental conditions specified in this documentare limited to those which can directly affect the performance of products. Only environmental conditions as such are considered. No special description of the effects of these conditions on the products is provided.

Environmental conditions directly related to fire or explosion hazards, microclimate within a product, and conditions related to effects from ionizing radiation are excluded. Any other unforeseen incidents are also excluded.

A limited number of classes of environmental conditions is given, covering a broad field of application.