Winding Wire

Need to purchase some winding wire? TEMCo will help you pick the right magnet wire for you. Call us at 877.474.8209 or view our online product selection by clicking the links below.

View our winding wire selection here:

Soderon 155 » GP/MR-200 »


What is Winding Wire?

Winding wire is another name for magnet wire. It is a copper or aluminium wire coated with a very thin layer of insulation or enamel that is used to change electric energy into winding energy.


Magnetic wire can be found in applications which require tight coils of wire, including hard disk drives, transformers, electromagnets, loudspeakers, motors and inductors.

Winding Wire for Motor Winding Wire for Speaker Winding Wire for Transformer

Winding Wire Specifications

Conductor Type

Winding wire will almost always be made of either copper or aluminum.

Give than aluminum has lower overall conductivity than copper does, aluminium requires a cross-section that is 66% larger than a copper would require in order to achieve equal ratings. For this reason, aluminum wire takes up more space than copper wire.

Transformer wire is usually made from copper that is electrolytic-tough pitch (ETP), also called oxygen-free copper. Larger transformers, which are lower voltage and have kilovolt-amperes (kVA) greater than 15, will sometimes use aluminum wire.

The wire in the voice coil of a loudspeaker can be, in rare cases, made of silver, though copper or aluminum is much more common. Silver is a better conductor of electricity than copper, but is much more expensive since it is a precious metal. Aluminum wire raises the resonant frequency of the voice coil, which allows it to respond more easily to higher frequencies.

AC induction motors consist of three parts: a stator, a rotor and an electromagnet. Each one has its own coil.

The stator coil can be either copper or aluminum, but copper coils are the norm since the higher conductivity of copper helps to enhance the motor’s electrical efficiencies.

In most cases, rotor conductors are die-cast in the shape of a squirrel cage but they can be designed with wound-rotor motors instead. While die-cast rotors are typically made of aluminum, with copper becoming more common recently, winding rotors can be made of either aluminum or copper.


There are three main wire shapes: square, round and rectangular.

How tightly the wire can be coiled will depends on the shape. Square wires will create tighter coil as they will have less space between the turns. Square wires are used in confined spaces and applications that require higher power and a wire with a larger gauge.

Round wires will not fit together as tightly, creates large gaps between the turns.

Rectangular wires lay flat. They are laminated into strips and are the most easily wound. Rectangular wire can be used in larger power transformers that operate at high voltages.

Voice-coil wires can sometimes be hexagonal.

Solid vs. Stranded Winding Wire

Solid wire, which can also be called solid-core or single-strand wire, is one strand of insulated wire. Solid wires is not easily bent, and are typically going to be used in applications where the wires do not need to be frequently moved.

Stranded wire is a group of wires braided together, which makes them more flexible than solid wires; the flexibility of the wire increases with the amount of strands the wire has. Stranded wire have a minimum of seven strands: six wires wrapped around one in the middle.

The flexibility of the stranded wire helps to curb metal fatigue. This occurs when a wire is continuously subjected to loading and unloading, which can cause the wire material to begin to crack.

Due to having less surface area, solid wire is also less susceptible to corrosion.

Solid Winding Wire Stranded Winding Wire

Pictured above: Solid winding wire (left), stranded winding wire (right)

Litz Wire

Litz wire is another form of stranded wire. It contains multiple separately insulated stranded wires braided together.

Radio frequency inductors, and transformers that are high-frequency, will often use litz wire to minimize the skin-effect and proximity effect losses.

Skin effect: An alternating current that is concentrated in the top layer of a wire, causing an increase in the wire’s effective resistance. The skin depth, or how deep the current is flowing in the wire, will be around a centimeter for a wire running at 60 Hz.

Proximity effect: an alternating magnetic field flowing through a conductor can produce eddy currents in conductors that are adjacent. Eddy currents can result in a change in the distribution of current in a wire. The current in the adjacent wire may pool in the part of the wire that is farthest away from other conductors carrying current in the same direction.


Wire insulations are going to be either a yarn made out of polyester or fiberglass, a thin varnish, or possibly both. The insulation enhances the wire's thermal endurance.

Square or rectangular wires that have thicker insulations can come with an additional high-temperature tape that is made out of polyimide or fiberglass. The windings are also covered with a varnish that extra insulating and is meant to help improve both the wire’s strength, as well as its reliability.

The turns of bare wires, which do not have any insulation, would not be able to not touch each other. Insulated wire can be wound so that the wires do touch, since the insulation will protect the wire from shorting itself out. In the case of a wire needing to have hundreds or thousands of turns, the wire will require protection from insulation.

The thermal capacity and diameter (which is measured in both millimeters or inches) are dependant on the type of insulation used.

Large power transformers that operate at high voltages may be insulated by oil-impregnated paper or pressboard.

TEMCo offers Soderon 155 wire, which has a polyurethane insulation with a polyamide overcoat, and will a thermal rating of 155°C. We also offer the GP/MR-200 wire, which comes with a polyester-imide insulation overcoated with polyamide-imide, which has a thermal rating of 200°C. Both of these wires come with a double coat of insulation.

Soderon 155 wire with a polyurethane insulation overcoated with polyamide, which will have a thermal rating of 155°C, and GP/MR-200 wire with a polyester-imide insulation overcoated with polyamide-imide, which has a thermal rating of 200°C, are both sold by TEMCo.

Wire Gauge

Wire diameter can be determined by the American wire gauge (AWG) rating of the wire. AWG is used in the U.S. and Canada to represent specific characteristics of round wire, such as diameter, resistance and current.

Diameter and AWG number are inversed: as one decreases, the other number increases. A wire that has a diameter of 5.827 millimeters will have a correlating AWG size of 3, while a wire with a diameter measuring 0.101 millimeters will have an AWG size of 38. The smallest gauge wire will have a diameter of 11.684 mm, while the largest gauge wire has a diameter of 0.0799 mm.

In total, there are 44 standard wire gauges. They range from 0000-40.

Winding Wire Gauge


Like the wire diameter, wire weight will be based on AWG standards and will have an inverse relationship with the gauge, meaning as the gauge becomes greater, the weight of the wire will decrease.

For accuracy, winding wire is measured by weight, rather than length.

The largest wire weight is 640.5005 lbs per 1000 feet, with a gauge of 0000. For a 40 gauge wire, the weight is 0.0299 lbs per 1000 feet.

Temperature Rating/Thermal Class

The thermal class, or temperature rating, is the temperature at which the wire will have a service life of 20,000 hours. The service life of the wire will be extended if the wire is used at a lower temperature.

The thermal class will depend on what insulation is being used. 130°, 155°, 180° and 200° are common temperature ratings found in different types of insulation. The maximum thermal class is 250°.

Thermal class is measured in degrees celsius.

Bondable Winding Wire

Bondable wire contains an extra adhesive film on top of the usual insulation that activate when heated up. It will bond the turn to turn windings of the wire into a self-supporting coil. eliminating the need for bobbins, the spindles around which the wire is wound.

Bonding agents include epoxy, polyester and polyamide.

Solvent, oven and resistance are the three main types of bonding.

  • Solvent bonding will be applied either while the wire is winding, or the coiled wire will be dipped in the solvent after the winding has completed.
  • Oven bonding is when the wire is put into an oven after it is fully wound in order for the turns to bond. Oven bonding can take 10 to 30 minutes, depending on the size of the coiled wire.
  • Resistance bonding requires an electric current to heat up the completed coil, which will then cause the wire turns to bond. The amount of voltage and time necessary to complete the process are dependent on the size of the wire and the design of the coil. Resistance bonding is typically used for wire sizes 34 gauge or higher.

Soldering Process

The winding wire will eventually need to be soldered. Soldering is the process of fusing two metals together by melting another metal that will join the other two together when it solidifies.

The majority of wire currently will not need to have its enamel removed before being soldered, since the insulation is mean to act as a flux when burned. For older wire the insulation might need to be removed before the soldering process can begin.

Aluminum is not easily soldered, and so connections can corrode and fail with time.

Breakdown Voltage

Breakdown voltage indicates the dielectric strength of the enamel insulation of the wire. The breakdown voltage can be of 3 types: Grade 1, Grade 2 and Grade 3. Insulations with higher grades will have higher breakdown voltages. Higher ambient temperatures result in a reduction of breakdown voltage.

The insulation thickness, or build, is the measurement of the enamel that has been added to the circumference of the bare wire. It can be determined by subtracting the total diameter of the wire from the diameter of the insulation and wire added together.

Insulation build can be single, heavy, triple or quadruple, with single and heavy being the most common.

Wires with smaller gauges will have higher breakdown voltages.

Where can I purchase my Winding Wire?

Click the links below to see the winding wire selection offered by TEMCo. There are wires available in numerous different gauges, temperature ratings and insulations. Purchase your winding wire from TEMCo today!

View Soderon 155 Wire Selection View GP/MR-200 Wire Selection

Call us at 877.474.8209