IEC 61439-3:2024 CMV contains both the official standard and its commented version. The commented version provides you with a quick and easy way to compare all the changes between IEC 61439-3:2024 edition 2.0 and the previous IEC 61439-3:2012 edition 1.0. Furthermore, comments from IEC TC SC 121 experts are provided to explain the reasons of the most relevant changes, or to clarify any part of the content.

IEC 61439-3:2024 defines the specific requirements for distribution boards intended to be operated by ordinary persons (abbreviated DBO throughout this document, see 3.1.101) as follows:
- assemblies intended to be operated by ordinary persons (e.g. switching operations and replacing fuse-links), e.g. in domestic (household) applications;
- assemblies containing outgoing circuits with protective devices intended to be operated by ordinary persons, complying e.g. with IEC 60898-1, the IEC 61008 series, the IEC 61009 series, IEC 62606, IEC 62423 and IEC 60269-3;
- assemblies for applications where the nominal voltage to earth does not exceed 300 V AC (see Table G.1 of IEC 61439-1:2020);
NOTE The voltage limits for DC applications are under consideration.
- assemblies with a rated current (Inc) of the outgoing circuits not exceeding 125 A and a rated current (InA) not exceeding 250 A;
- assemblies intended for use in connection with the generation, transmission, distribution and conversion of electrical energy, and for the control of equipment consuming electrical energy and for associated data processing;
- enclosed, stationary assemblies;
- assemblies for indoor or outdoor use.
This second edition cancels and replaces the first edition published in 2012. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous edition:
a) alignment with the structure of IEC 61439-1:2020;
b) inclusion in the scope of more examples of the type of protection and control devices;
c) deletion of type A and Type B DBOs;
d) addition of a new Annex BB related to DBOs used in a prosumer’s electrical installation (PEI);
e) addition of a new Annex CC related to rated current of a DBO with additional source of supply in parallel/simultaneously with another source that is connected to the DBO e.g. PV.