IEC 60317-31:1990 specifies the requirements of glass-fibre wound, polyester or polyesterimide varnish-treated, bare or grade 2 enamelled rectangular copper winding wire, temperature index 180.  NOTE For this type of wire, the heat shock test is inappropriate and therefore a heat shock temperature cannot be established. Consequently, a class based on the requirements for temperature index and heat shock temperature cannot be specified. The enamelled wire shall be based on one of the following standards and shall be agreed between purchaser and supplier.
- IEC 60317-16:1990, Specifications for particular types of winding wires - Part 16: Polyester enamelled rectangular copper wire, class 155
- IEC 60317-28:1990, Specifications for particular types of winding wires - Part 28: Polyester­imide enamelled rectangular copper wire, class  180
- IEC 60317-29:1990, Specifications for particular types of winding wires - Part 29: Polyester or polyesterimide overcoated with polyamide-imide enamelled rectangular copper wire, class 200
- IEC 60317-30:1990, Specifications for particular types of winding wires - Part 30: Polyimide enamelled rectangular copper wire, class 220
When an enamelled wire is used, it must have a minimum class of 155.