IEC 60309-4:2021 applies to self-contained products primarily intended for industrial use, either indoors or outdoors that combine the following items within a single enclosure: – a fixed or portable socket-outlet according to IEC 60309-1 or IEC 60309-2 with a rated operating voltage not exceeding 1 000 V DC or 1 000 V AC with a frequency not exceeding 500 Hz and a rated current not exceeding 800 A; – a switching device. This second edition cancels and replaces the first edition published in 2006 and Amendment 1:2012. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: – updated in order to take into account the technical revisions to IEC 60309-1 and to IEC 60309-2. This document is to be read in conjunction with IEC 60309-1:2021 and with IEC 60309‑2:2021.