Motor Wire

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Soderon 155 » GP/MR-200 »


What is Motor Wire?

Motor wire will be either copper or aluminum and will be found in electric motors, which are used to convert electrical energy into mechanical motion.

Motor Wire Applications

Electric motors are used in applications such as fans, blowers, pumps, machines, household appliances, power tools, and disk drives.

Large electric motors can be used in equipment that powers the propulsion systems of large ships. The smallest motors will be used in applications such as electric wristwatches.

Motor Wire Motor Wire

AC vs. DC Motors

AC stands for alternating current, whose current flows in one direction for a period of time and then switches direction, a process it repeats over and over again continuously. DC stands for direct current, and has current that starts at one place and flows in one direction to the end destination.

AC motors are more efficient than DC motors, because you need lower current to perform the same task that a DC motor would require more voltage to do. The advantage of a DC motor is that you can control the speed of better than an AC motor.

You will find DC motors where there is a slow but constant speed needed, in applications like rock crushers and car crushers. AC motors you will be used in factories, given their faster startup speed.

AC induction motors have a stator, a rotor and an electromagnet, each one has its own separate 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, motor rotors can be made of either aluminum or copper.

DC motors have a wound rotor, which is also called an armature, and either a stator that is either wound or a permanent magnet. The rotor has one or more coils wound around a laminated ferromagnetic core shaft.

Motor Wire Specifications

Conductor Type

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

Wires that are made from metals that are better electrical conductors will run more efficiently than metals that are don’t conduct electricity as well. Poor electrical conductors will create wasted heat. Aluminum has lower overall conductivity than copper does, requiring a cross-section that is 66% larger than a copper wire would need in order to achieve equal ratings. Copper is the highest conducting non-precious metal.

Due to its high electrical conductivity, copper is commonly used in motor coil windings, bearings, collectors, brushes, and connectors.


How tightly the wire can be wound depends on the shape of the wire, which will be either square, round or rectangular.

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 that have a larger wire gauge.

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

Rectangular wires are laminated into strips and lay flat, making them the most easily wound.

Solid vs. Stranded Motor Wire

Solid wire, which can also be called solid-core or single-strand wire, is made up of one strand of insulated wire. Solid wires are not very elastic.

Stranded wire is made of a bunch of bare wires braided together. Stranded wires are far more flexible than solid wires; the flexibility of the wire goes up with the amount of strands the wire has. Stranded wires have, at least, seven strands of wire: six wires wrapped around one in the middle.

The flexibility of the stranded wire helps to prevent metal fatigue, which happens when a wire is subjected to a lot of loading and unloading. Eventually, the wire material will begin to crack.


Motor wire insulations are going to be out of a polyester or fiberglass yarn or a thin enamel.

Wires that have thicker insulations can come with a high-temperature tape made out of a polyimide or fiberglass material. The coils are also coated with a varnish that adds extra insulation and improves the wire’s strength and reliability.

The turns of bare wires have no protection from insulation, so the wire turns 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. Wires often need hundreds, or even thousands, of turns, meaning the wire will require protection from insulation.

The diameter, measured in both millimeters or inches, along with the thermal capacity and AWG wire sizes, will be based on the type of insulation used.

Insulations used on motor wire include formvar, polyurethane, polyester, and polyester-imide.

TEMCo sells Soderon 155 wire and GP/MR-200 wire. Both of these wires are double coated.

Double coated wire is used to strengthen the wire, and increase its durability. It also allows the wire to take on the properties of both insulations. For example, the GP/MR 200 has a polyester-imide insulation overcoated with polyamide-imide, which gives the wire higher dielectric properties and chemical resistance to common solvents and refrigerants. The Soderon 155 has a polyurethane insulation with a polyamide overcoat, giving it higher resistance to solvents and better windability.

Wire Gauge

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

The gauge of the wire increases, the wire diameter and weight will decrease.

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.

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.

The reason that wire is measured in weight, rather than length, is for accuracy, since it is much easier to simply weight a wire than to measure out what could amount to miles of wire.

Motor Wire Gauge

Temperature Rating/Thermal Class

The temperature at which the wire will have a service life of 20,000 hours is called the temperature rating. Using the wire at a lower temperature will extend the service life even further.

Different insulations have different temperature ratings. 130°, 155°, 180° and 200° are common temperature ratings found in different types of insulation. The maximum temperature found is 250°.

Soldering Process

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

The majority of wire does not require having its insulation removed before it is soldered, but this ultimately depends on the type of wire. Some, like the GP/MR-200 wire offered by TEMCo, will need their insulation to be removed, while the Soderon 155 wire will not, since the insulation is meant to act as a flux when burned.

Aluminum is not easily soldered, which can cause connections to corrode and fail with time.

Breakdown Voltage

Breakdown voltage suggests the dielectric strength of the insulation.

The breakdown voltage can be of 3 types: grade 1, grade 2 or grade 3. Wires with smaller gauges will have higher breakdown voltages.

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

Buy Motor Wire

TEMCo offers a variety of motor 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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