IEC Technical Committee 55: Winding wires

Scope: To prepare international standards for wires for electrical winding, irrespective of conductor material, shape, size or type of covering, taking into account the needs in all fields of electrical engineering, with attention to the need for environmental protection and safety of human health. Winding wire standards cover product specifications, test procedures and packaging.

All of today’s major worldwide electrotechnical trends, in particular wires for e-mobility, renewable energy and energy distribution, are sufficiently covered in the broad scope of TC 55.

As shown on the TC 55 dashboard. The structure was last reviewed at the TC 55 plenary meeting held 28 October 2025 in Mexico.

The winding wire industry is a mature industry, one that continually evolves to meet the demands of expanding applications of its products. Present standards reflect the consensus of the members for the technology and materials represented. Changes are based on new technology as they apply to methods of test and material for products and packaging, new product designs, or in addressing environmental and health considerations.

Winding wires are used widely throughout a broad spectrum of electrotechnical industries mainly for creating electromagnetic fields and transforming electrical energy. The range of applications of winding wires extends from the use of extremely fine wires for electronics and telecommunications applications, to the use of large insulated and covered wires for large motor and power transformation industries. Demand and use of winding wires are slowly increasing worldwide as industrialization is proceeding and demand for electricity and more automated solutions grows particularly in less industrialized regions. The winding wire industry is renowned for its innovative solutions, both in products and production processes. For example, electrification of vehicles has become an increasingly important factor for new properties (and testing) of winding wires in large volumes.

The Committee continually analyzes and incorporates in its standards and the trends and changes in market demand for all types of winding wires traded between countries.

Although some applications are not asking for improved properties of winding wires, an increasing quality standard regarding properties of winding wires such as elongation, continuity, breakdown voltage and thermal characteristics can be observed especially in the automotive sector. Wires with thicker insulating layers are requested more often in this industry. In several projects these market expectations are taken into account, since process technology of the production of winding wires have also been improved over the years and the state of the art developed further to higher standards. The increasing expectations from the market are due to increasing quality and performance standards in motor and transformer business. Motors and transformers constantly must become more efficient, have an increased density of power and/ or higher life expectations at higher temperatures. All this leads to less tolerances in winding wires (broadly requested), less faults per given length etc. The automotive industry is driving additional technological trends due to compact, energy efficient traction motors, some of which are required to operate at higher voltages such as 800V+.

The winding wire industry is a very mature one, because winding wires are commodities. This is because in the present-day market, the industry is present and well developed virtually everywhere in the world.

Winding wires are not end products, but components used by customers as materials in electrical equipment for creating electromagnetic fields and transforming electrical energy.

The sustainability of the market is difficult since it is closely linked with the fluctuations of general economic trends. Since the winding wire industry is strongly connected with the trends of end user markets (automotive, domestic appliances, electrical rotating machinery, transformers, solar and wind energy conversion and distribution, other electrical equipment), the specific technical demands of the end users are very influential on the market. One continuing trend in certain regions of the world is the continually greater demand for aluminium winding wires due to increases in the price of copper, which led to new specifications for rectangular aluminium wires.

As such, IEC TC 55 strives to maintain a cooperative relationship with main end user representatives on the Committee and with other relevant IEC TC's, in order to open new scenarios in the future of the industry, to:

1. Maintain an awareness of new trends in relevant technology to the winding wires industry;
2. Investigation into improved and partially more complex and multi-factor test methods including pulse endurance testing;
3. Investigation into new tests such as tensile strength for round copper enamelled wires, windability, and new methods for flexibility and adherence, that adapt to changing usage conditions;
4. Standardization for new types of winding wires in response to market demand or improved / higher quality levels of existing wire types
5. Investigation into aging testing for plastic spools; and
6. Support the use of environmentally sound materials and processes in the production and use of winding wires. Examples of this support through standardization include:
   
   Increased activity toward environmental protection led to lower exposure limits of the solvent NMP (N-Methylpyrolidone) (in the EU), but compliance can be achieved by existing winding wire manufacturers.

Ongoing participation in the work of the Technical Committee and its Working Groups by producers, suppliers and users is highly encouraged. TC 55 actions to take place:

1. Support test methods respecting environmental protection and human health.

Although not addressed specifically in IEC standards, the winding wire industry employs solutions in the manufacturing process to minimize the presence of solvents in finished products.

In general, the winding wire industry serves the role of material supplier to end product manufacturing industries represented in the following TC's:

IEC TC 2, Rotating machinery

IEC TC 14, Power transformers

IEC SC 61C, Safety of refrigeration appliances for household and commercial use

IEC TC 96, Transformers, reactors, power supply units, and similar products for low voltage up to 1100 V

The winding wire industry is a supplier to, but also the customer of sectors represented in the following TC's:

IEC TC 15, Solid electrical insulating materials

IEC TC 112, Evaluation and Qualification of Electrical Insulating Materials and Systems

IEC TC 113, Nanotechnology for electrical and electronic products and systems

Cooperation with these TC's is demonstrated through the exchange of documents and liaisons.

In order to maintain contact, interface, and obtain current information/documents with these other IEC committees, TC 55/WG 1 members are assigned to be liaisons to these other committees. The assigned liaisons will be expected to report on the activities of these parallel IEC committees at TC55/WG1 meetings.

TC 55 standards do not specify how to deal with the management of tests (routine vs. non-routine/periodic). These are certification issues not governed by the standards. In some countries there are some local rules, but generally decisions are taken by agreement between customer and supplier.

The scope of TC 55 standards encompasses only the product requirements and does not extend to the management of certification matters or supplier-customer agreements.