Specifies the requirements of enamelled round copper winding wire of class 155 with a sole coating based on polyester resin, which may be modified provided it retains the chemical identity of the original resin and meets all specified wire requirements. Class 155 is a thermal class that requires a minimum temperature index of 155 and a heat shock temperature of at least 175 °C. The temperature in degrees Celsius corresponding to the temperature index is not necessarily that at which it is recommended that the wire be operated and this will depend on many factors, including the type of equipment involved. The range of nominal conductor diameters covered by this standard is as follows: - grade 1: 0,020 mm up to and including 3,150 mm; - grade 2: 0,020 mm up to and including 5,000 mm. The nominal conductor diameters are specified in Clause 4 of IEC 60317-0-1. The main changes with respect to the previous edition are listed below: - new requirements for appearance, Subclause 3.2, added; - the constant K, applied in calculating the number of revolutions for the peel test, Clause 8, increased from 130 mm to 150 mm; - the test temperature for the cut-through test, Clause 10, increased from 240 °C to 270 °C;