Inductor Wire

If you're looking for inductor wire, our guide below can help you select the correct wire for your needs.

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What is an Inductor?

The main function of an inductor is to resist an instant change in current. It is a passive electronic component that stores energy in its magnetic field. An inductor typically consists of a wire loop or coil. The wire's inductance is tied to the number of turns in the coil as well as the radius of the coil and the inductor core material.

Inductor Wire

What is Inductor Wire?

Most inductor wire is made of magnet wire, meaning they are copper or aluminum with a thin insulation, wrapped around a core made of air, ferromagnetic or ferrimagnetic material. Low frequency inductors have cores of laminated steel.

Most inductor wire coils come with wire exposed on the outside, but some have their wires completely enclosed; these coils are known as "shielded".

Inductor Wire Specifications


Inductor wire will be square, round or rectangular, and the shape of the wire will affect how tightly it can be wound.

Square and rectangular wires can be coiled tighter than round wires because there will be less space between the turn of these wires. Square wires are used in confined spaces and applications that require higher power and that have a larger wire gauge. Rectangular wires are laminated flat strips and are used in large inductors that function at high voltages.

Round Inductor Wire Rectangular Inductor Wire

Solid vs. Stranded

Solid wire, or solid-core/single-strand wire, is one single strand of insulated wire. Solid wires do not have much elasticity, and are found in applications where the wires do not often move.

Stranded wire, is made up of multiple bare wire strands braided together into one larger wire, making them more flexible than solid wires and easier to install. The flexibility of the wire increases as the number of strands goes up; the minimum number of strands is seven: six wires wrapped around one in the middle.

One big advantage to using stranded wire is its resistance to metal fatigue, which occurs when a wire is routinely subjected to constant loading and unloading, which can cause the wire material to begin to crack. Since it is flexible, stranded wire has a higher resistance to this problem.

There are some disadvantages to using stranded wire, though, including its increased susceptibility to corrosion because of its greater surface area.

Solid Inductor Wire Stranded Inductor Wire

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


Inductor wire will have insulations of either a thin varnish or a yarn made out of material such as polyester or fiberglass.

The purpose of insulation is to enhance the thermal endurance of the wire and to make sure it is protected from shorting out when it is wound. The turns of wires that are bare, those without any insulation, are not able to not touch each other. In the case of a wire needing to have hundreds or thousands of turns, the wire will require protection from insulation. Inductor wire will always be insulated.

The wire's thermal capacity and diameter (which can be measured in both millimeters and inches) will be dependant on the insulation coating the wire.

TEMCo supplies Soderon 155 wire and GP/MR-200 wire, both of which are double coated.

Double coating wire has two purposes: to strengthen the wire, and increase its durability. Double coating also lets the wire take on the characteristics of each insulation. GP/MR 200 has a polyester-imide insulation and a polyamide-imide overcoat, giving the wire greater dielectric properties and chemical resistance. Soderon 155 has polyurethane insulation with an overcoat of polyamide, providing it with higher resistance to solvents and greater windability.

Insulated Inductor Wire

Wire Gauge

American wire gauge (AWG) is used to represent specific standard of round wire, such as diameter, resistance and current. It is used in the United States and Canada. In total, there are 44 standard wire gauges. They range from 0000-40.

Diameter and weight act inversely to the gauge: as one decreases, the other increases.

0000 gauge wires weigh 640.5005 lbs per 1000 feet and have a diameter of 11.684 mm, while a 40 gauge wire weighs 0.0299 lbs per 1000 feet and has a diameter measuring 0.0799 mm.

Wire is measured in weight, rather than length, for accuracy, given that it is much simpler to weigh a wound wire than it is to measure long distances of wire.

Inductor Wire Gauge

Temperature Rating/Thermal Class

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

Different insulations contain differing temperature ratings, with 130°, 155°, 180° and 200° being common. The maximum thermal class is 250°.

Thermal class is measured in degrees celsius.

Bondable Inductor Wire

Bondable wire creates a self supporting coil, eliminating the need for bobbins, the spindles around which the wire is wound. It achieves this with an extra adhesive film, made of agents like epoxy, polyester and polyamide, on top of the usual insulation that activates when heat is applied to it. The adhesive will bond the turn to turn windings together.

These are three of the techniques for creating a self supporting coil:

Solvent bonding will require the completed coiled to be dipped in the solvent after the winding has completed. This can also be applied to the wire as it is being wound.

Oven bonding necessitates that the wire be heated up in an oven after it is fully wound. Oven bonding time typically ranges from 10 to 30 minutes, with larger coils taking longer.

Resistance bonding: the completed coil will be heated up by an electric current. The voltage and time required for completing resistance bonding are dependent on both the size and design of the wire coil. This process typically takes place with wires 34 gauge or higher.

Soldering Process

The inductor wire will eventually need to be soldered to either a circuit board, or to another wire. To do this, a metal that has a lower melting point, most likely lead or tin, will be melted down and will merge the wires together when it solidifies.

Most wire can be soldered without having its insulation removed, but this depends on the type of wire. Some, like the GP/MR-200 wire offered by TEMCo, will need their insulation to be removed, while others, like the Soderon 155 ,wire will not.

Aluminum is does not solder easily, leading to an increase in the likelihood of corrosion and failure.

Breakdown Voltage

Breakdown voltage designates the dielectric strength of the wire insulation.

Breakdown voltage indicates the dielectric strength of the enamel insulation of the wire and is dependant on the insulation build., which is the measurement of the enamel that has been added to the circumference of the bare wire. Insulation build can be single, heavy, triple or quadruple, with single and heavy being the most common.

The thicker the insulation the higher the breakdown voltage will be. Wires with smaller gauges will have higher breakdown voltages.

The breakdown voltage can be of 3 types: Grade 1, Grade 2 and Grade 3, with higher grades meaning higher breakdown voltages.

Inductor Types

Ferromagnetic Core

Ferromagnetic core and ferrite core inductors have a core made of a magnetic material, which will increase the inductance of the coil.

The magnetic core can also experience losses of power that is being transferred through the device, resulting in dissipated heat. These losses can be caused by eddy currents, hysteresis and nonlinearity.

Eddy currents are swirling electric currents, called eddies, that occur when a conductor is exposed to a changing magnetic field. The eddies can induce a change in current and can cause a resistive loss, resulting in dissipated heat. The larger the area inside the eddie current, the more energy that will be lost.

Hysteresis happens when the magnetic field is reversed, causing a small amount of energy to be lost, depending on what the core material is made of.

Nonlinearity is when current is so high it saturates the core, meaning that increased force will no longer lead to increased magnetization. This then causes inductance of the coil to change with the current through the device instead of remaining constant.

Ferrite Core

Ferrite is a non conductive ceramic material, which can be made of nickel, zinc, or manganese compounds, among others.

Soft ferrite will be used in higher frequency inductor cores since they have low coercivity, which allows them the magnetic field to reverse without losing as much energy as ferromagnetic cores. This reduces the effects of hysteresis. They also have high resistivity, which means they will not be subject to eddy currents.

Air Core

An air core inductor has a coil that has a support core made of non magnetic material, such as plastic or ceramic. This term may also apply to self-supporting coils.

While air core coils have low inductance, they are used in inductors that have high frequencies because they do not experience the same core losses as a coil with a ferromagnetic core.

Laminated Core

Low-frequency inductors have iron core that are laminated with low-coercivity silicon steel. This is done to increase the iron's resistivity, or its ability to resist the flow of electricity, since iron is a good conductor.

The core contains a stack of thin steel laminations that have an insulating coating on the surface to prevent eddy currents between the sheets.

Toroidal Core

Toroidal inductors have a circular, ring-shaped magnetic core and are used in applications such as high-frequency coils and transformers.

Toroidal inductors can have higher Q factor, or ratio of reactance to resistance, and higher inductance than other coils, due to the smaller number of turns of the toroidal inductor.


One of the terminals of a variable inductor might have a sliding spring contact which is able to move along the coil, allowing it to either increase or decrease the turns of the coil.

It might also involve a moveable magnetic core, which can be slid in or out of the coil. When moved farther into the coil, the core will increase the permeability and the inductance.

Radio Frequency

Radio frequency inductors mostly have air cores. They come with higher resistance, which can result in losses due to:

  • Skin effect: When alternating current concentrates in the surface layer of a conductor, thus leading to an increase in the wire's effective resistance. This happens because radio frequency current travels along the surface of the wire, rather than deeper inside the wire.
  • Proximity effect: When an alternating current flows through a conductor, it creates an alternating magnetic field around it, which then induces eddy currents in conductors that are adjacent. These eddy currents alter the distribution of current in the nearby wire, resulting in the current concentrating in the parts of the wire that are furthest away from the other wires carrying current in the same direction.
  • Parasitic capacitance: Unwanted capacitance, or stored charge, that exists between individual wire turns of a coil because of their proximity to each other. It will not result in energy losses but may alter the way the coil behaves, including causing it to become self-resonant.

One of the ways that radio frequency inductors combate these losses is by using litz wire, which contains multiple insulated wires braided together. By having each wire separately insulated, it distributed the current equally among them, eliminating the proximity and skin effects.

Buy Inductor Wire

See TEMCo's full line of inductor wire below. We carry American-made wire with a variety gauges, temperature ratings and insulations.

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

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