In our previous article, we talked about the possibility of having problems using CCA (copper clad aluminum) wire. CCA wire can be found almost everywhere, and is particularly attractive to the cost conscious ham because of it’s relatively low price as compared to pure copper wire. Much CCA wire seems to be coming from outside the United States, where the process of bonding copper to aluminum or steel in increasingly thinner outer layers has been perfected.
So what, you ask? Doesn’t “skin effect” make the use of CCA wire as compared to OFC (oxygen free copper) unimportant? Skin effect you may recall is the phenomenon that causes electrons to flow on the outer circumference of a wire rather than within its core. Well, “skin effect” only takes place when wire is used at high frequencies, and not at D.C. (direct current) potential. So, if you’re using cat 5 or 6 CCA cable for your high speed internet connections, you may get away with shorter runs of it, but if you’re using CCA cable to power your mobile rig (either in the home or car), you will suffer the consequences, no matter the length! Even in cat 5 and 6 cables, where copper is bonded to aluminum or steel, the copper clad cable, especially when used over greater distances, will suffer data loss which will result in slower data speeds.
So, what are the consequences of using copper clad wire versus pure copper conductors? First of all, OFC (copper) wire offers much improved corrosion resistance over CCA (copper clad aluminum) wire.
The second, and most important difference is that the resistance of CCA wire over copper is significantly greater. It’s estimated that the gauge of CCA wire must be at least two gauge sizes higher to achieve the same transfer of energy. Saying it another way, if you’re using 12 gauge 100% copper wire to power your station, you’d need about an 8 gauge CCA cable to achieve the same transfer of energy. Then too, the tensile strength of aluminum is not as great as copper. Thus, your copper clad aluminum wire will break off quite easily when compared to pure copper conductors.
The gauge size difference depends upon the thickness of the layer of copper that’s plated on to the aluminum core. Obviously, the thinner the coating of copper, the greater the cable loss per foot. Recall in the beginning of part one of this two part article, I was surprised when I attempted to solder to my copper clad aluminum wire. The copper coating was so thin that it burned off quickly, leaving me with an aluminum wire which would not “take” solder. The less copper that’s used, theoretically the less expensive the cable will be. So, frugal hams seeking a bargain will undoubtedly be attracted to the lowest per foot of cable price, which as we’ve discussed above, may very well have the greatest loss and fastest deterioration factors.
In summary, my advice is to stay away from CCA cable, no matter it’s application. You’ve been warned!
by Rick Fearns, K6VE
