This International Standard specifies the electrical and mechanical characteristics of concentric lay stranded overhead electrical conductors, containing one or more selfsupporting aluminium or aluminium alloy layer(s) as depicted in Figure 1, made of combinations of any of the following metal wires: a) hard-drawn aluminium as per IEC 60889, designated A1; b) aluminium alloy type A or B as per IEC 60104, designated A2 or A3; c) thermal resistant aluminium alloy type as per IEC 62004, designated AT1, AT2, AT3 or AT4; d) regular strength steel as per IEC 60888, designated S1A or S1B; e) high strength steel as per IEC 60888, designated S2A or S2B; f) extra-high strength steel as per IEC 60888, designated S3A; g) aluminium-clad steel as per IEC 61232, designated 20SA, 27SA, 30SA or 40SA. NOTE This standard covers the construction of self-damping conductors, as well as gap-type conductors. Although both types of conductors share a common design feature and the presence of one or more gaps between layers, they are intended for different purposes. Self-damping conductors (SDC) may have more than one gap to provide increased self-damping, whereas gap-type conductors are so designed as to allow the aluminium layers to slide freely over the core during installation, and therefore usually do not require more than one gap. The various metal combinations permitted by this standard shall be in accordance with Table 1.