IEC 60721-3-3:2019+AMD1:2026 CSV – Classification of environmental conditions

Environmental classification is the first step in any robust product qualification programme. IEC 60721-3-3:2019+AMD1:2026 CSV addresses this step for equipment installed permanently in weatherprotected locations, defining parameter groups and severities that engineers can translate into test planning and specification writing.

Standard Information

IEC 60721-3-3:2019+AMD1:2026 CSV classifies the groups of environmental parameters and their severities to which products are subjected when installed for stationary use at weatherprotected locations. The consolidated version incorporates Amendment 1 into the third edition. Its content is maintained under the IEC technical committee responsible for environmental classification. - Designation: IEC 60721-3-3:2019+AMD1:2026 CSV
- Full title: Classification of environmental conditions - Part 3-3: Classification of groups of environmental parameters and their severities - Stationary use at weatherprotected locations
- Status: Current
- Publication date: 2026-09-15
- ICS classification: 19, 19.040
- Technical committee: TC 104

Scope and Application

The standard covers products that are installed for stationary use at weatherprotected locations. It classifies groups of environmental parameters and their severities, so that manufacturers, specifiers and test houses share one vocabulary for the conditions a product must withstand during such use. Rather than prescribing test methods, it defines the environmental classes from which test severities and design assumptions are derived. This third edition cancels and replaces the second edition published in 1994, Amendment 1:1995 and Amendment 2:1996, and constitutes a technical revision. The changes are extensive: definitions and Clause 4 alignment follow IEC 60721-3-1, and Clause A.3 has been incorporated into Clause 5. Subclause 5.2 replaces all existing climate classes with completely new classes, divided into two groups, reflecting the latest revision of IEC 60721-2-1 and its new climate types. Further revisions add a new class for low air pressure in Subclause 5.3 and Table 2, and replace all mechanically active substances classes (Subclause 5.6, Table 4) and all mechanical conditions classes (Subclause 5.7, Table 5) with completely new classes in alignment with IEC 60721-3-1. Defined values of chemically active substances are now given by reference to ISO 9223. Table 1 presents new climatic classes with new severities. Annex A is revised and includes a clean climatogram; Annex B is revised and includes the definition of seismic environment. All classes regarding fire, all combined classes, all chemically active substances classes, Clause A.2 and Annexes C, D and E have been removed.

Products and Materials Covered

No product family is excluded by designation; the classification applies to any product, equipment or material installed for stationary use at weatherprotected locations. Typical contexts include indoor industrial plants, control rooms, workshops and storage areas where products are not exposed to direct weather but still face temperature, humidity, air pressure, mechanically active substances and mechanical conditions. The ICS classifications 19 and 19.040 place the document within testing and environmental engineering broadly. It therefore serves electrical and electronic products as well as other engineered goods whose environmental robustness must be specified. The classification frames conditions only; product-specific performance requirements remain governed by the relevant product standards.

Testing and Compliance Considerations

Classification standards of this type are used at the specification stage rather than as test method documents. An accredited laboratory typically begins by assigning the applicable environmental classes with the client, then maps the classified severities to the corresponding basic test severities in the relevant test standards. This mapping makes test planning traceable from installation environment to laboratory condition. For type testing, the class selection recorded in the test plan serves as the acceptance reference. Documentation should state the class for each parameter group, the laboratory conditions applied and the observed performance, so that procurement and quality functions can verify conformity against the declared installation environment. Retest triggers deserve attention. Because this edition replaces all climatic, mechanically active substances and mechanical conditions classes, products qualified against the superseded classes may need reassessment when contracts or specifications cite the new edition. A design change, a change of installation environment or a customer requirement referencing the current classes each justify review of the original classification decision.

Related Standards and Series Context

The designation itself conveys the document structure. IEC 60721 is a series numbered under a single root, and "Part 3-3" indicates a subdivision of Part 3, which classifies groups of environmental parameters and their severities by use situation. The suffix "2019+AMD1:2026 CSV" denotes the base edition year consolidated with its Amendment 1 through the Combined Standard Version format, giving users the amended text in a single document. The series logic follows the pattern common to IEC environmental publications: one part set defines broad environmental condition categories, while other parts classify parameter groups for specific use profiles. Readers should obtain the authoritative document from official IEC sources, as this page is an interpretive overview only.