What is CCA?
The most common alternative to copper used in the electrical industry is aluminum. Widely used in power distribution, many aluminum cables are buried under the road as power cables. CCA is an aluminum conductor with a thin copper coating. It’s made by encasing a rod of aluminum in a layer of the copper strip which is butt-welded along the seam to totally encase the aluminum. The entire rod is drawn through a series of rollers and dies to reduce the diameter to as little as 0.1mm, just over the thickness of a human hair. The main disadvantages are its lack of flexibility, higher resistance, and lower conductivity compared with copper.
This means you have to use more of it to carry the same current or amps. In a power cable management, this is not normally a problem as you only have to go up a size or two. It results in a bigger overall cable using more insulation, sheathing and armoring, but the savings made over an equivalent copper cable are considerable. Aluminum is also used in some high-frequency coaxial cables where aluminum can perform better than copper at very high frequencies (GHz). In both these cases, the aluminum is bare (silvery in color) and is easily spotted. It is not being disguised to look like copper.
CCA does have some advantages over solid copper, mainly surrounding weight and cost. CCA is significantly lighter than copper and in some applications can offer advantages in cable containment and handling. Aluminum is around a third of the price of copper and therefore provides cost savings for network cable manufacturers over solid copper conductors. Theft is also less likely with scrap values largely reduced. It also has better corrosion resistance than plain aluminum.
What is CCS?
CCS (copper-clad steel) is similar to CCA in that a steel conductor is thinly coated with a layer of copper. Steel gives higher mechanical strength than aluminum but is heavier and less flexible. It is of course also less conductive than copper. It’s manufactured in the same way as CCA, whereby the applied copper is drawn down to smaller diameters through rollers and dies.
The higher mechanical strength makes for a robust alternative to copper which minimizes physical damage during installation compared to aluminum. Problems arise when both CCA and CCS are passed off as pure copper cables. Neither is suitable for applications where pure copper has been specified and can cause long-term problems which can be costly to rectify once the cable has been installed.
What is CCC?
Another significant problem is the use of recycled copper as a conductor material. Known as CCC (Copper Clad Copper), these conductors use low-grade copper alloys made from mixing recycled copper with impurities such as brass, tin, and other contaminants and forming them into an 8mm rod. This is then clad in copper foil and reduced using the same process as CCA resulting in a conductor full of impurities with a very high oxygen content and resistance that may be even higher than aluminum. This can be very difficult to spot as the conductor looks ‘yellow-ish’ (much like copper when cut through). The best way to check is to measure the resistance of the conductor if you have the right equipment.
What are the hazards associated with CCA and CCS?
The main problems are that aluminum and steel have a much higher resistance than copper. This leads to a decrease in current capacity resulting in the cable overheating and potentially leading to a fire. Aluminum is also far more brittle than copper and this can lead to breakages during installation.
These cables are also prone to fatigue at the point of termination which can cause random faults. This is particularly true with insulation displacement connectors (ICD). Alarm systems using CCA could lead to false readings and false alarms whilst with coaxes it leads to degradation of picture quality, particularly over long distances.
Why this is a problem?
One of the difficulties is that even on close inspection it can be very difficult to spot CCA. As the cable is cut there is a tendency for the copper to smudge over the cut end of the aluminum making it look like solid copper. Sometimes it’s possible to tell with a magnifying glass or a simple burn test using a cigarette lighter. Aluminum has a higher melting point than copper for example.
CCA must not be simply dismissed out of hand, however. Some applications, short runs, for example, CCA could well work to an acceptable standard. In this case, make sure you are aware of what you are buying and are receiving a significant cost saving. In some applications, the savings may be worthwhile whereas, in others, the return visits and customer dissatisfaction will be too great.
Conclusion
Talk to your cabling suppliers and make sure you are aware of what is being supplied. Resistance may not be a problem over short runs. In some cases, the cost-saving can be attractive but make sure you have considered the application and what the installation is intended to achieve.
If like most users, you want to simply ‘install and forget it may be better to stick with pure copper conductors and benefit from their proper performance characteristics. Check the standard that the cable should meet, if pure copper is specified it has been done for a reason, in which case you need to question if substituting CCA or CCS is a good idea.
English
中文
