Copper-clad aluminium wire (CCAW or CCA) is a dual metal electrical conductor composed of an inner aluminium
Aluminium (aluminum in AmE, American and CanE, Canadian English) is a chemical element with the Symbol (chemistry), symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately o ...
core and outer copper
Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish ...
cladding.
Uses
The primary applications of this conductor revolve around weight reduction requirements. These applications include high-quality coils, such as the voice coils in headphones or portableloudspeaker
A loudspeaker (commonly referred to as a speaker or speaker driver) is an electroacoustic transducer that converts an electrical audio signal into a corresponding sound. A ''speaker system'', also often simply referred to as a "speaker" or ...
s; high frequency coaxial applications, such as RF antennas and cable television
Cable television is a system of delivering television programming to consumers via radio frequency (RF) signals transmitted through coaxial cables, or in more recent systems, light pulses through fibre-optic cables. This contrasts with bro ...
distribution cables; and power cables.
CCA was also used in electrical wiring for buildings. The copper/aluminium construction was adopted to avoid some of the problems with aluminium wire, yet retain most of the cost advantage.
CCA is also seen in counterfeit unshielded twisted pair networking cables. These cables are often less expensive than their full-copper counterparts, but
the official specifications such as Category 6 cable
Category 6 cable (Cat 6) is a standardized twisted pair cable for Ethernet and other network physical layers that is backward compatible with the Category 5/5e and Category 3 cable standards.
Cat 6 must meet more stringen ...
require conductors to be pure copper. This has exposed the manufacturers or installers of cable with fake certification to legal liabilities.
Properties
The properties of copper-clad aluminium wire include: * Less expensive than a pure copper wire * Lighter than purecopper
Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish ...
* Higher electrical conductivity
Electrical resistivity (also called specific electrical resistance or volume resistivity) is a fundamental property of a material that measures how strongly it resists electric current. A low resistivity indicates a material that readily allows ...
than pure aluminium
Aluminium (aluminum in AmE, American and CanE, Canadian English) is a chemical element with the Symbol (chemistry), symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately o ...
* Higher strength than aluminium
* Electrical connections are typically more reliable than pure aluminium{{Citation needed, date=December 2015
* Typically produced as a 10% or 15% by copper volume product
Skin effect
Theskin effect
Skin effect is the tendency of an alternating electric current (AC) to become distributed within a conductor such that the current density is largest near the surface of the conductor and decreases exponentially with greater depths in the cond ...
forces alternating current
Alternating current (AC) is an electric current which periodically reverses direction and changes its magnitude continuously with time in contrast to direct current (DC) which flows only in one direction. Alternating current is the form in which ...
to flow on the outer periphery of any wire; in this case, the outer copper cladding of the conductor which has lower resistance than the mostly unused aluminum interior. The better conductor on the outer path causes the wire's resistance at high frequencies, where the skin effect
Skin effect is the tendency of an alternating electric current (AC) to become distributed within a conductor such that the current density is largest near the surface of the conductor and decreases exponentially with greater depths in the cond ...
is greater, to approach that of a pure copper wire. This improved conductivity over bare aluminum makes the copper-clad aluminium wire a good fit for radio frequency
Radio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around to around . This is roughly between the uppe ...
use.
The skin effect is similarly exploited in copper-clad steel
Copper-clad steel (CCS), also known as copper-covered steel or the trademarked name Copperweld is a bi-metallic product, mainly used in the wire industry that combines the high mechanical resistance of steel with the conductivity and corrosion ...
wire, such as the center conductors of many coaxial cable
Coaxial cable, or coax (pronounced ) is a type of electrical cable consisting of an inner conductor surrounded by a concentric conducting shield, with the two separated by a dielectric ( insulating material); many coaxial cables also have a ...
s, which are commonly used for high frequency feedlines with high strength and conductivity requirements.
See also
* Copper conductorReferences