No. It is a voluntary international standard. However, many countries have adopted it as a national standard (often with modifications). In the EU, the Low Voltage Directive (LVD) presumes compliance with EN 61439-1.
is the first part of the IEC 61439 series, titled "Low-voltage switchgear and controlgear assemblies – Part 1: General rules." It specifies the general definitions, service conditions, construction requirements, technical characteristics, and verification procedures for low-voltage assemblies. iec 61439-1 standard pdf
Under normal operation, temperature rises must not exceed specified limits in Table 6 (e.g., for terminals, busbars, and internal components). This prevents fire hazards and insulation degradation. iec 61439-1 standard pdf