IEC 61439 Design Verification: Testing, Comparison and Assessment
design verification: Design verification proves that a switchboard design genuinely achieves its declared ratings under IEC 61439, and it is carried out once per design rather than on every board. The standard recognises three equivalent methods: testing, comparison with a reference design (calculation) and assessment against design rules, with the permitted methods defined separately for each characteristic.
Contents
- What is the difference between design and routine verification?
- How is one of the three verification methods chosen?
- Which characteristics are verified?
- Duties of the original and the assembly manufacturer
- Documentation and the technical file
- Key takeaways
- Frequently asked questions
- Related articles
The two concepts most often confused in the switchboard world are design verification and routine verification. Routine verification is an outgoing inspection applied to every board that is built; design verification proves once and lastingly that the design family to which the board belongs meets its declared ratings. IEC 61439-1 allows that proof to be produced in three different ways and specifies in tabular form which way is valid for which characteristic. This article looks at the three methods, the twelve verification characteristics and the split of responsibility between original manufacturer and assembly manufacturer.
What is the difference between design and routine verification?
Design verification proves that a particular assembly design achieves characteristics such as declared rated current, short-circuit withstand strength, temperature rise, insulation properties and degree of protection. It is done once, remains valid as long as the design is unchanged, and the result is kept in the technical file. Routine verification, by contrast, is an outgoing inspection repeated for every assembly produced: enclosure and connection checks, insulation resistance or dielectric test, continuity of the protective circuit and functional checks. Neither replaces the other: an assembly whose design has not been verified is not compliant even if it passes every routine test.
How is one of the three verification methods chosen?
The first method is testing: real conditions are created on a sample and the result is measured. The second is comparison with a reference design, where an already tested design is taken as a starting point and compared by calculation within the limits defined in the standard. The third is assessment, where compliance is demonstrated against the design rules given in the standard. The three methods are treated as equivalent, but not all of them are available for every characteristic; dielectric properties, for example, can only be verified by test, while short-circuit withstand can be verified by test or comparison. Choosing correctly has a marked effect on both cost and verification time.
Which characteristics are verified?
The standard lists the characteristics to be verified under twelve headings: strength of materials and parts, corrosion resistance, properties of insulating materials, resistance to ultraviolet radiation, lifting, mechanical impact, durability of markings, degree of protection, clearances and creepage distances, protection against electric shock and continuity of the protective circuit, short-circuit withstand strength, electromagnetic compatibility, temperature rise, dielectric properties and mechanical operation. Some headings are covered by data supplied by the enclosure manufacturer, while others depend on the design decisions of the company building the board. Temperature rise and short-circuit withstand strength are in practice the two most demanding headings.
Duties of the original and the assembly manufacturer
| Verification characteristic | Permitted methods | Practical notes |
|---|---|---|
| Dielectric properties | Testing only | Applied on a sample, cannot be replaced by calculation |
| Short-circuit withstand strength | Testing or comparison | Deviation limits from the reference design are defined in the standard |
| Temperature rise | Testing, comparison or assessment | Requires device loss data and an enclosure heat balance |
| Degree of protection (IP) | Testing or assessment | Usually covered by the enclosure manufacturer report |
| Clearances and creepage | Testing or assessment | Measurement and record at the least favourable point |
| Mechanical operation | Testing | Doors, interlocks and withdrawable units tried over an operation count |
The standard defines two roles. The original manufacturer designs the assembly system and takes on its verification, delivering a system that includes layout rules, busbar cross-sections, permitted device combinations and mounting instructions. The assembly manufacturer applies that system in accordance with the rules and performs routine verification. Any change beyond the system rules, such as a different busbar cross-section or an unforeseen device arrangement, calls for the relevant design verification heading to be revisited. This separation is critical to keeping responsibility clear across the supply chain.
Documentation and the technical file
Verification results are kept in the technical file, which contains design drawings, the device list, calculation reports, test reports and rating plate information. The CE marking rests on this file, and third-party certification is not mandatory, although a customer specification may call for an independent laboratory report. Keeping the file traceable means being able to show which verification heading a later revision affected. Good practice is to update a verification matrix with every design revision and keep on a single page which heading was closed by which method.
Key takeaways: design verification
- Design verification is done once per design — routine verification is repeated for every assembly.
- The three methods are equivalent but not universal — dielectric properties can be verified by test only.
- The original manufacturer supplies the system rules — changes beyond those rules trigger re-verification.
- Evidence is collected in the technical file — the CE declaration rests on it and third-party certification is not mandatory.
- Standard source — IEC publication catalogue: iec.ch.
Frequently asked questions
Do I have to test every board?
No. Design verification is per design and is not repeated for boards that stay within the same system rules. The only obligation applied to every board is routine verification. A configuration that leaves the system rules, however, becomes a new verification subject.
Can short-circuit withstand be verified by calculation?
Partly. The standard permits comparison with a previously tested reference design and defines acceptable deviation limits. Once those limits are exceeded, testing becomes unavoidable; a fully free calculation method is not accepted.
Who prepares the technical file?
The assembly manufacturer who places the board on the market. The file contains the system verification reports obtained from the original manufacturer, its own calculation and routine test records, drawings and rating plate data. Keeping the file up to date is the manufacturer’s responsibility.
Related articles
- Routine Verification Tests: Dielectric, Continuity and Function
- What is the IEC 61439 Standard? Type Testing and Conformity in Low Voltage Switchgear.
- Short Circuit Withstand in Switchboards: Icw, Ipk and Conditional Rating
- All technical articles
Devpan assemblies are designed inside verified system rules, and the method used for each verification characteristic is recorded traceably in the technical file. Contact us to clarify the verification scope for your project together. Related Devpan solution: electrical panel design services.
