This part of IEC 60317 specifies the requirements of solderable enamelled round copper winding wire of class 155 with a dual coating. The underlying coating is based on polyurethane resin, which may be modified providing it retains the chemical identity of the original resin and meets all specified wire requirements. The superimposed coating is based on polyamide resin. NOTE A modified resin is a resin that has undergone a chemical change, or contains one or more additives to enhance certain performance or application characteristics. The range of nominal conductor diameters covered by this standard is: – Grade 1: 0,050 mm up to and including 1,600 mm; – Grade 2: 0,050 mm up to and including 1,600 mm. The nominal conductor diameters are specified in Clause 4 of IEC 60317-0-1:2013.