IEC 61439-4:2023 is available as IEC 61439-4:2023 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.

IEC 61439-4:2023 defines the specific requirements of ACS as follows:
- assemblies for which the rated voltage does not exceed 1 000 V in case of AC or 1 500 V in case of DC;
- assemblies where the nominal primary voltage and the nominal secondary voltage of transformers incorporated in ACS are within the limits specified above;
- assemblies intended for use on construction sites, both indoors and outdoors, i.e. temporary places of work to which the public do not generally have access and where building construction, installation, repairs, alteration or demolition of property (buildings) or civil engineering (public works) or excavation or any other similar operations are carried out;
- transportable (semi-fixed) or mobile ASSEMBLIES with enclosure.
This second edition of IEC 61439-4 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 IEC 61439-1:2020 regarding the structure and technical content, as applicable.