IEC 60121: Commercial Aluminium Conductor Wire — The Most Basic Overhead Line Material

Commercial Annealed Aluminium Wire — The Most Basic Overhead Conductor Material

IEC 60121 specifies commercial annealed aluminium conductor wire (AAC). Unlike the alloy conductors of IEC 60104 (AAAC), pure aluminium offers higher conductivity (~61% IACS vs. ~53% IACS) but half the tensile strength. AAC suits short-span, low-stress distribution lines, not long-span transmission.

Selection logic: AAC = high conductivity, light, cheap, low strength. ACSR = highest strength, heavy, magnetic hysteresis loss. AAAC = balanced conductivity, strength, and losses. The choice is fundamentally a four-way trade-off: conductivity × strength × weight × cost. No perfect material — only the optimal compromise for the span and voltage.