IEC 60317-51:2014 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 meets all specified wire requirements. 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. The nominal conductor diameters are specified in Clause 4 of IEC 60317-0-1:2013. This second edition cancels and replaces the first edition published in 2001. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: - new 3.2.2 containing general notes on winding wire, formerly a part of the scope; - new 3.3 containing requirements for appearance; - revision to references to IEC 60317-0-1:2013 to clarify that their application is normative; - New Clause 23, Pin hole test. Keywords: solderable enamelled round copper winding wire of class 180, polyurethane resin