What is a CCA conductor?

CCA (copper clad aluminium) consists of an aluminium conductor coated with a thin layer of copper. (Generally 10 to 15% copper)

CCA uses the principle of the "skin effect". When an alternating current travels through a conductor, it tends to be distributed on the surface rather than in the core of the conductor. The higher the frequency, the greater this phenomenon and the more the signal travels on the surface.

It therefore appeared beneficial to use CCA in network infrastructures. However, other electrical parameters, such as resistance, attenuation and return losses are affected by the use of CCA in twisted pair cabling components.

Although CCA has the advantage of being less expensive for the manufacturer, it can result in significant additional costs for the network installer or owner. Its mechanical and electrical performances do not meet the requirements of a network cabling infrastructure.

CCA aluminium cable	Gigamedia 100% copper cable

 

The mechanical properties of CCA

From a mechanical point of view, CCA is characterised by a lack of malleability compared to copper. Actually, patchcords are manipulated quite every day. Using CCA in this type of component can induce a premature conductor breakage. In this case, the time spent investigating the cause of the fault on the network may result in significant additional operational costs.

 

	copper	CCA 10%	CCA 15%
Copper content (%)	100	10	15
Breaking strength (tensile N/mm2)	220-270	120-190	150-230
Density (kg/dm3)	8,9	3,3	3,63

example of typical nominal values - sources: Elektrisola.

With CCA, premature oxidation also occurs when the aluminium is exposed to air. In network cabling systems, termination of RJ45 keystones is mostly based on the insulation-displacement contact system (IDC). With this widely used termination technique,  the insulated wire is pressed into the IDC contact & the insulation is removed, exposing the conductor and the aluminium to the air (because the thin layer of copper has also been removed). This can create a hotspot affecting the electrical performances.

 

And from an electrical point of view?

CCA resistance is higher rather than copper, thus lowering the conductivity.

The elevated resistance of CCA results in overheating within the cable bundles. This temperature increase affects attenuation within cables (the ideal operating temperature is around +20°C). Attenuation is a critical parameter for communication networks and must be controlled in order to guarantee operation over distances of 100m. The use of CCA in network cabling systems involves a reduction cabling distances.(T°C De-rating factor)

The use of CCA in network cabling systems also has an impact on remote DC power supplies (PoE/PoE+). The effect of the increased resistance is a far greater voltage drop than with copper. Here too, the maximum cabling distance is reduced.

Consequently, standard IEEE802.3at (PoE+) recommends, at least, ISO/IEC 11801 Class D (CAT5e) or better cabling to support PoE+. To achieve resistance characteristics that comply with class D, the system installed (complete channel) must provide a DC loop resistance (looped with 2 conductors from the same pair) below 25 ohms. Yet CCA generates an increase in DC resistance of at least an additional 35- 40% compared to copper.

Rloop = R1 + R2
 

	Copper	CCA 10%	CCA 15%
Copper content (%)	100	10	15
Conductor resistance AWG24 (Ω/m)	0,089	0,135	0,130
Conductor resistance AWG26 (Ω/m)	0,139	0,216	0,208

example of typical nominal values - sources: Elektrisola
 

When using CCA cables or cords, DC loop resistance is raised and therefore has an impact on the maximum cabling distance.

Besides the cabling distance, the far greater voltage drop for CCA affects the proper operation of PoE/PoE+. The Design guidelines established by ISO/IEC 11801 and IEEE 802.3at/af do not apply to CCA conductors. PoE+ is based, for example, on a maximum voltage drop of 7.5V, calculated on the basis of the electrical properties of a 100% copper conductor.

When performing on-site measurements (acceptance tests), there are almost always surprises in terms of return loss (measurement of the reflected signal travelling in the opposite way & that may disturb the transmitter of the active equipment) where some of the channel's components include copper coated aluminium.

Ultimately, using CCA in a network cabling infrastructure could produce errors during system certification tests (for a number of parameters) and therefore, jeopardise acceptance by the end client, and result in additional costs for removal/replacement and re-certification.

Does CCA comply with current standards?

At no point do bodies such as ISO/IEC or CENELEC authorise the use of conductors other than those made from copper for twisted pair cabling, for either capillary network cables or stranded patch cables .

The ISO 11801 design/installation standard for network pre-cabling requires the use of standardized components listed in categories (5e, 6, 6A), which must satisfy the IEC design & performance requirements. (The IEC standards are manufacturer oriented)

In each of the IEC 61156 or EN 50288-1 documents, setting out the guidelines for manufacturing twisted pair cables type (Cat5e, CAT6 or CAT6A, etc.), the use of CCA is very clearly ruled out (extract from IEC 61156: "The conductor shall be a solid or stranded annealed copper (…)")

In the case of a non-compliant system, there is generally a considerable risk for the purchaser.

Marking a cable made from copper clad aluminium as ISO 11801 or even IEC 61156 constitutes fraud on the part of the seller , but the purchaser is generally not informed.

Watch this video explaining how to rapidly identify and carry out performance tests on CCA and copper cables: