IEC 61439 : frequently asked questions (part 3)

Here are simple answers to 3 other questions about the new IEC standard :

7. Which of the original manufacturer and of the switchboard manufacturer is responsible for the switchboard?

The new standard takes better into account the organisation of the market and clarifies the allocation of responsibilities.
As before, the panelbuilder is responsible for the final switchboard by designing it according to his customer’s specifications and to the “original manufacture’s” instructions, and by carrying out the routine tests.
The original manufacturer is still responsible for the design of the Assembly system and of the quality of the parts he sells.

8. Today I carry out a temperature rise test on switchboards equipped with a given manufacturer’s devices and when I use the devices of another manufacturer I calculate the power loss according to the data given by the manufacturer => Is it the same way with the new standard?

This practice complies neither with the former standard nor with the new one.
Regarding temperature rise, the standard requires strict conditions to allow substitution of a device by another one:
– The rated current and the physical arrangement must be maintained (in particular the length and cross-sectionnal area of the connections)
– The power loss of the new device must be the same or lower than the initial device’s one
– The temperatures of the terminals of the new device when it’s tested according to the IEC 60947-X standard must be the same or lower than the initial device’s ones

NOTE: In addition, all the other verification must be done again, especially the short-circuit test.

9. Because there are much more methods of verification, can I comply with the new standard without carrying out tests?

No. As the former standard, the new one is still mainly based on type tests.
It defines more accurately the verification of a variant by comparison with a configuration already tested.
Furthermore, but for temperature rise tests only, the new standard gives two calculation methods based on safety margins and applicable within tight limits of power and complexity of the switchboard.


  • Kindly advise me what is the acceptance criteria/acceptance tests for low and medium voltage switchboards

    • Generally speaking, these acceptance criteria / tests should be listed by the end-user or designer in their specification file. There are of course the existing IEC (or UL / Nema) standards for LV or MV switchgear assemblies, which end-users should ask as a minimum requirement in my opinion, to ensure a good level of safety of people, reliability of the switchboard along its life duration … but not all end-users require this minimum compliance today, as far as I know, it depends a lot on country and application you are talking about. Just as an example, for LV switchboard you can refer to the IEC60439-1, which is in the process of being replaced by the new IEC61439-2 (see this link to know more). For medium voltage switchboards, you can refer to IEC 62271-2xx standards (HV assemblies)

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