Generator Wire

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Soderon 155 » GP/MR-200 »


What is a Generator?

A generator converts mechanical energy to electrical energy. It uses coils of made of copper that spin inside large magnets at high speeds.

Smaller generators coils can sometimes be self-excited, meaning that the generator is being powered by the current it produces.

Large power generators will often have a separate smaller generator that is used to power the field coils of the larger generator.

What is Generator Wire?

Most generators contain coils wound with magnet wire, meaning the wires are copper with a thin insulation.

Generator Wire

Generator Wire Specifications


Wires are generally either square, round or rectangular, though hexagonal wires also exist.

Wire shape affects the tightness of the coil, with square and rectangular wires creating tighter coils than round wires. This is simply due to their being less space between the turn of the wires with edges. Square wires are used in confined spaces and applications that require higher power and that have a larger wire gauge. Rectangular wires are used in large, high voltage generators.

Solid vs. Stranded Wire

Solid wire is a single strand of insulated wire, while stranded wire is multiple wire strands braided into a larger wire.

Solid wires are not very elastic, so they used in environments where the wires do not often move. Stranded wires are much more bendable, as the flexibility of the wire will increase with the number of strands the wire has. Stranded wire has a minimum of seven wires: six strands that are wrapped around one strand.

Stranded wire has advantages and disadvantages. Its flexibility, which leads to easier installation, also gives it high resistance to metal fatigue. Metal fatigue are breaks in the wire that are a result of a wire being subjected to too much loading and unloading,. Since it is flexible, stranded wire is less likely to crack.

The downside of stranded wire is its greater surface area increases the likelihood of the wire corroding.


Insulation is added to a wire for a simple reason: to make sure it is protected when it is wound. The turns of wires that are bare, those without any insulation, are not able to touch each other as this would result in the wire shorting itself out. That is why, in the case of a wire needing to have hundreds or thousands of turns, the wire will require the protection provided by insulation. Generator wire will always be insulated.

Insulations can include:

  • Polyester-imide - high thermal endurance and solvent resistance, comes with increased windability because of low friction.
  • Polyamideimide - used for inverter duty and motors that may see voltage spikes.
  • Formvar - flexible and high abrasion resistance.
  • Polyester Nylon - dual coated insulation: polyester basecoat and nylon topcoat. Polyester has high thermal properties, nylon has high mechanical properties.
  • Polyester-amide-imide - dual coat insulation: polyester basecoat, amide‐imide outer coating. Increased windability, more heat shock resistance and a greater overload capacity.
  • Dacron glass - either unvarnished or varnished with organic material or silicon. A combination of glass and polyester fibers. Good flexibility and is abrasion resistance.
  • Polyamide-ML - resistant to chemical solvents and burnout. High ability to withstand overload and ability to not be affected by exposure to varnish solvents.

Soderon 155, which has a polyurethane insulation with a polyamide overcoat, and will a thermal rating of 155°C., is offered by TEMCo. We also offer the GP/MR-200 line, which has a polyester-imide insulation overcoated with polyamide-imide, and a thermal rating of 200°C. Both of these wires are double coat insulated.

Wires with double insulations take on characteristics of both insulations, along with increased strength and durability. GP/MR 200 has higher dielectric properties and chemical resistance to common solvents and refrigerants because of its insulation, while Soderon 155 is resistant to solvents and has very high windability.

American Wire Gauge

American wire gauge, or AWG, represents standards for solid, round wire, including their diameter, resistance, weight and current. In total, there are 44 standard wire gauges that go from 0000-40. AWG is mostly used in the United States and Canada.

Diameter and weight both go up as the AWG number goes down.

A 0000 gauge wires come with a weight of 640.5005 lbs per 1000 feet and a diameter of 11.684 mm. A 40 gauge wire has a weight of 0.0299 lbs per 1000 feet, with a diameter measuring 0.0799 mm.

Generator Wire Gauge

Temperature Rating/Thermal Class

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

Different insulations contain differing temperature ratings.

130°, 155°, 180° and 200°, all measured in degrees celsius, are common.

Bondable Generator Wire

Bondable wire is another name for a coil that is self supporting, which eliminates the spindles that the wire is usually wound around, called bobbins. An extra adhesive film, which will activate when heat is applied to it, is applied on top of the standard insulation. The adhesive will bond the turn to turn windings together.

Bonding can be done one of three different ways:

  • Solvent bonding - the completed coiled is dipped in solvent after the winding has completed, or it can be applied to the wire during the process of being wound.
  • Oven bonding - the fully wound wire will be heated in an oven. This is typically a 10 to 30 minute process, with larger coils taking a longer time to bond.
  • Resistance bonding - the finished coil, usually one with a wire gauge of at least 34, will have an electric current heat it. Completing resistance bonding is entirely dependant on how big the coil is and how it is designed. This will determine how much voltage the coil needs and how long it will take.

Soldering Process

To solder generator wire, two wires are fused together, or to a circuit board, by soldering. The process involves a third metal with a lower melting point, lead or tin for example, which will be melted and then will merge the wires together.

Most wire doesn’t need to have its enamel removed before it is soldered, but this depends on the wire. Some, like the GP/MR-200 wire offered by TEMCo, will have their insulation removed before the wire can be soldered, while the Soderon 155 wire will not, since the insulation will act as a flux when it is burned.

Breakdown Voltage

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

Buy Generator Wire

TEMCo offers a variety of generator wire. View the selection simply by clicking the links below. All of TEMCo’s wire is made in the USA.

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

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