IEC 61439-4:2012 specifies requirements for assemblies used on construction sites, including both temporary and transportable or mobile assemblies. These assemblies must have a rated voltage not exceeding 1,000 V for a.c. or 1,500 V for d.c. and include transformers with primary and secondary voltages within these limits. The standard applies to assemblies used indoors and outdoors on construction sites, where public access is generally restricted and where construction, installation, or demolition activities occur. This first edition replaces IEC 60439-4 (2004) and introduces significant changes such as a revised title to "Part 4: Particular Requirements for Assemblies for Construction Sites (ACS)," alignment with IEC 61439-1, and provisions for comparing tested ACS.