This part of IEC 60317 specifies the requirements of solderable enamelled round copper winding wire of class 180 with a sole coating based on polyurethane resin, which may be modified providing it retains the chemical identity of the original resin and meet all specified wire requirements. Class 180 is a thermal class that requires a minimum temperature index of 180 °C and a heat shock temperature of at least 200 °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: 0,018 mm up to and including 1.000 mm; - Grade 2: 0,020 mm up to and including 1.000 mm.