IEC 61439 : frequently asked questions (part 4)

Answer to a question asked by Joy in another post, which I copied here :

“Does the new standard , require the panel builder to supply only ,the same branded circuit breakers ,which were used on the type tested assembly in their client panels ?

Is so , doesn’t it limit the available options for the panel builder as he will be restricted with only one brand of circuit breakers for all his future projects?”


As far as I understand it, with the new IEC 61439 standard, it will be impossible, in practice, to substitute a device from one brand, used in a type-test, by a similar device from a different brand, without making a new type-test, because the 2 following conditions should be fulfilled:

1/ Temperature rise (sub-clause of new IEC61439-1)

the alternative device should have :

* a power loss less than or equal to the original device : this part could be ok
* a physical arrangement within the functional unit which is the same (cross-section of the connexions …) : this can be difficult to manage or prove as shape and size of devices are not the same
* a temperature rise on its terminals, when tested in accordance to the relevant product standard (IEC60947 series …), that is less than or equal to the original device : this, in practice, is impossible to check as these temperature values are not published by manufacturers

2/ Short circuit (table 13 from sub-clause 10.11.3 of new IEC61439-1)

* the original and substitution device should be from the same manufacturer : that in itself already answers the question!
* the device manufacturer is prepared to certify that the alternative device is equal or better than the original device in all relevant respects (short-circuit withstand characteristics, safety perimeter …) : I am sure manufacturers will be more than ready to help on that point !

Already with the existing standard, this was not really possible, especially to be fully type-tested (TTA) : the new standard is just more precise, when the existing one was more subject to interpretation.

Another way to put it, in my opinion, and to be fair : it will no more be possible to state that a switchboard is compliant and type-tested according to the new IEC 61439 without at minimum (but not only) having done short-circuit tests with the same or very similar type (same brand) of devices : having witnessed a number of short-circuit and internal arc tests, sometimes on configurations which failed the test, I find it reassuring for the safety of people (and goods) …

It will still be possible for some panel builders to do that, of course, but they won’t be able to say they are compliant to the new IEC 61439.

Somehow, it seems to me that it will be easier than today, from an end-user’s point of view, to differentiate one from the other.


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