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Only Connnect: On CCA & CCS cables
This week’s blog is brought to you in association with FS Cables who have produced a great guide to CCA (copper clad aluminium) and CCS (copper clad steel).
What is CCA?
CCA is an aluminium conductor with a thin copper coating. It is made by encasing a rod of aluminium in a layer of copper strip which is butt-welded along the seam to totally encase the aluminium. 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. Aluminium is a cheaper, less conductive metal than copper and substituting CCA substantially reduces the copper content and therefore the cost of producing the cable.
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 aluminium, but is heavier and less flexible. It is of course also less conductive than copper. It is 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 minimises physical damage during installation compared to aluminium.
Problems arise when both CCA and CCS are passed off as pure copper cables. Neither are 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 are the cables affected?
The cables mainly affected are internal telephone cables – CW1308 style, alarm cables and coaxes. Some manufacturers are also offering Cat-5 and other data cables as CCA.
What are the hazards associated with CCA & CCS?
The main problems are that aluminium and steel have a much higher resistance than copper. This leads to a decrease in current capacity over longer distances. Aluminium 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).
On 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 is this 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 aluminium making it look like solid copper. Sometimes it is possible to tell with a magnifying glass or a simple burn test using a cigarette lighter. Aluminium has a higher melting point than that of copper for example.
Problems emerge where unscrupulous suppliers pass off CCA as genuine copper which often can go unnoticed until an error occurs.
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 on others, the return visits and customer dissatisfaction will be too great.
What measures should you take?
Talk to your supplier 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’ you may be better to stick with pure copper conductors and benefit from their proper performance characteristics.
Aluminium conductors and braids have been widely used for many years. Commscope for example, a major American manufacturer of coaxial cables, has been offering Aluminium braided coax for many years with some impressive test data. The danger for specifiers lies in manufacturers passing off CCA as pure copper to save on price.
Whichever you choose make sure you are aware of what you are buying – solid copper, copper covered aluminium or copper clad steel. There is a big difference.
Previous Only Connect entries:
* Only Connect: 2012 a year of change!
* Only Connect: New, contactless technology
* Only Connect: The future of interconnection
* Only Connect: IPC/WHMA-A-620 – Product innovation – Coaxicom adjustable RF Connector
* Only Connect: IPC/WHMA-A-620 – Revision B has been released
* Only Connect: Product Spotlight – IEC endorses four USB-IF standards
* Only Connect: Product Spotlight – Molex Minifit Jnr Connector series
* Only Connect: LVDS Cables, a simple guide
* Only Connect: 3M growing Twin Axial cable range
* Only Connect: On worldwide connector demand