This specification describes five grades of galvanized steel cables, consisting of round steel wires of four classes, according to the weight of the zinc coating, used as stays, messengers, cables between spans and similar purposes. 2 The five grades described are the following: 1) Light. 2) Common. 3) Siemens-Martín. 4) High resistance. 5) Extra-high strength. The minimum breaking loads are indicated in table 1. 3 The four classes according to the weight of the amount of zinc are: Type 1 and classes A, B and C. The minimum weights of the zinc layers are specified in the table 4.