Soft annealed copper is the most commonly used conductor in cable manufacturing because of its:

• High conductivity
• Ductility
• Corrosion resistance
• Fatigue resistance, and
• Ease of soldering

The 2 common conductor configurations are:

• Solid

Solid wire is rigid & more efficient at higher frequencies, Untinned solid copper is a more efficient power & data conductor than tinned solid or stranded wire.

• Stranded

Stranded wire has a much higher flexibility & can be easily bent & formed into wire & cable assemblies.

Stranded Conductor Configurations

• Bunched

Bunch strand has any number of strands twisted together with any given lay length and direction of lay (usually left-hand) without a symmetrical geometric arrangement of individual strands. Bunch-stranded wire is the most flexible and lowest-cost stranding configuration.

• Concentric

  • Composed of a central strand surrounded by one or more layers of helically-laid wires.
  • Greater mechanical strength & better crush resistance than other standard configurations.
  • Types of concentric stranded copper:
    • Conventional
      • The lay direction is reversed & lay length is increased for successive layers.
      • Lay direction of the outer layer is left-hand.
    • Equilay
      • All layers have the same lay length with direction of lay reversed in successive layers.
      
    • Unilay
      • All layers have the same length & direction of lay.
      
    • Rope Lay
      • Individual members are bunch or concentric stranded.
      • Around a central member, one or more helical layers of members are laid.
      

Copper Conductor

• ETP
  • Electrolytic tough-pitch, high conductivity copper is electrolytically refined to contain 0.02 and 0.04% oxygen, and less than 50 ppm total metallic impurities. This is normally supplied as the standard conductor material.
• OFHC
  • Oxygen-free, high-conductivity copper is produced in a protective reducing atmosphere that is low in hydrogen. OFHC copper is used to avoid embrittlement when the conductor is exposed to reducing atmospheres at elevated temperatures. It is available on special order.

Copper Size - American Wire Gauge

American Wire Gauge (AWG) is a U.S. standard set of non-ferrous wire conductor sizes. The "gauge" defines the wire diameter. AWG is most frequently applied to copper.

The higher the gauge number, the smaller the diameter. Larger diameter (lower gauge number) wire carries more current because it has less electrical resistance over a given length.

AWG is sometimes known as Brown and Sharpe (B&S) Wire Gauge

Circular Mil Area

A circular mil is a unit of areas equal to the area of a circle having a diameter of one mil (0.001"). The area of 1 circular mil is 0.0000007845 square inches (or 0.7845 square mils).

The circular mil area is equal to the square of its diameter in mils.

Circular mil area defines cross-sectional areas of conductors.

Comprehensive table of AWG and Metric wire sizes.