Cu Wire

What is Cu wire? Learn about copper wire and how to select the right kind for your application. Call TEMCo at 877.474.8209 or view our online product selection by clicking the links below.

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Soderon 155 » GP/MR-200 »


What is Cu Wire?

Cu is the chemical symbol for copper as it appears on the periodic table. Copper is the metal most commonly found in electrical wiring, as it has the highest electrical conductivity rating of all non-precious metals.


Cu wire is found in applications that will necessitate tight coils of wire. Copper wire can be used in a wide variety of applications, such as loudspeakers, motors, overhead lights, and telephone cords.

Cu Wire for Motor Cu Wire for Speaker Cu Wire for Telephone Cord


Square, Round, or Rectangular/Flat Cu Wire

Square wire has some benefits over round wire. Square wire will allow less space between the wire turns when the coil is formed. Square wire is most often used in confined spaces and for higher power applications that have a larger capacity and wire gauge.

Round wire will not fit together as tightly as square wire simply due to its shape, and will, therefore, have more space between the wires.

Rectangular/flat copper wire will be arranged in a plane and then laminated into a flexible plastic flat ribbon. Rectangular copper wire is easily wound, so edge-wound coil springs are typically made of flattened wire.

Rectangular Cu Wire Round Cu Wire

Pictured above: Rectangular wire (left), round wire (right)

Solid vs. Stranded Cu Wire

Solid copper wire is a single strand of insulated wire. It is also sometimes called solid-core or single-strand wire. Solid wires are not very flexible, and are used in applications where they will not be required to bend.

Stranded copper wire, on the other hand, will contain numerous wires braided together to form one larger wire.

Stranded wires have much more flexibility than solid wires; the more strands the wire has, the more flexible it will be. The minimum number of strands that a wire will contain is seven, with six wires wrapped around one in the middle.

Stranded wire has more surface area than a solid wire, so it is more susceptible to corrosion, but it also has a higher resistance to metal fatigue, which occurs when a wire is subjected to frequent loading and unloading, eventually causing the metal to crack. The flexibility of the stranded wire helps to prevent this problem.

Stranded wire is used in circuit board connections, audio headphones and connections that involve moving joints. Solid wire is found in electric motors, coils and magnet wiring.

Solid Cu Wire Stranded Cu Wire

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

Litz Wire

Litz wire is an example of stranded wire. It will contain multiple stranded wires braided together in order to reduce the skin effect and proximity effect.

When an alternating current becomes concentrated in the surface layer of a wire, leading to an increase in effective resistance, it called the skin effect. The depth of the current in the wire is known as the skin depth, which will be around a centimeter for a wire running at 60 Hz, and less at higher frequencies.

When an alternating magnetic field flows through a conductor, resulting in eddy currents in adjacent conductors, this is called the proximity effect. Eddy currents are swirling electric currents that can change the distribution of current in a wire. The current in the adjacent wire may concentrate in the part of the wire that are farthest away from other conductors that are carry current in the same direction.

Litz Cu Wire

Insulated vs. Bare Cu Wire

Insulated wire is made of either thin varnish/enamel or a yarn made out of polyester or fiberglass, though the wire may contain both in some cases. The insulation is meant to increase the wire's thermal endurance.

Bare wire does not have any insulation. The turns of the bare wire will short each other out if they touch each other, so the wire needs to be spaced out to avoid this. Insulated wire turns can touch, so for a wire that requires hundreds or thousands of turns, insulation will be necessary.

Bare wire applications include overhead power sources for transit systems, such as trains, buses, as well as industrial cranes. They are sometimes found in large inductors used in transmitters; in these cases the bare wire can be silver plated, which allows for greater conductivity.

Some common types of insulation are polyurethane, polyester, and polyamide. There are many different types of insulations and they all have different specifications, including gauge and temperature rating.

Insulated Cu Wire Bare Cu Wire

Pictured above: Insulated wire (left), bare wire (right)

Magnet Wire

Magnet wire, also known as enamelled wire, can be made of either copper or aluminium. It is then coated with a very thin layer of insulation.

Magnet wire is used to convert electric energy into magnetic energy and will be found in windings of numerous applications including transformers, inductors, generators, and electromagnets.

The conductivity of aluminum is much lower than copper, making it so that aluminum magnet wire requires a cross section that is 1.6 times larger than copper wire to create the same resistance.

Magnet Cu Wire

Tinned Wire/Tin-coated Cu Wire

Tinned wire is wire coated by tin.

Tinned wire is wire coated by tin, which is corrosion resistant and has high conductivity.

There are two ways to tin copper wire: the hot dipping method and the electroplating method.

In the hot dip method, the wire is coated by being dipped in melted tin. In the electroplating method, the wire will be coated in a tin salt solution, then will be connected to an electrical circuit. The current that is then passed through the wire will cause the metal ions in the tin salt solution to bond with the wire.

Tinned Cu Wire


Tinsel wire Cu wire is the most flexible type of wire. It is prepared by wrapping numerous copper foil strands around textile core. Due to the thinness of the foil, the wire becomes extremely bendable. Tinsel wire is good for resisting metal fatigue.

Tinsel copper wire can be utilized in telephones cords, handset cords and loudpeakers. There is a braided wire that comes out of the center of the speaker's voice coil that connects to the speaker tabs. This wire will be tinsel copper wire.

Where can I purchase Cu Wire?

Click to view the Cu wire selection below from TEMCo. Wires are available in different gauges, temperature ratings and insulations. Buy your Cu wire from TEMCo!

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