Quick Answer
Copper-clad aluminium has roughly 58 percent higher resistance than copper, which spends the PoE voltage budget before it reaches the device. It also runs hotter inside bundles and fractures at terminations. It is not TIA compliant and cannot form part of a certified channel.
The Listing That Looks Too Good
You have seen it: a thousand feet of Cat6 at a fraction of everyone else's price. Somewhere in the specification, usually in smaller type, sits the abbreviation CCA. That is copper-clad aluminium — aluminium conductor with a thin copper plating, typically ten to fifteen percent copper by volume. On a Power over Ethernet install it fails in three independent ways, and the failures compound.
Resistance, Which Is Really Voltage Drop
Aluminium's resistivity is about fifty-eight percent higher than copper's. Same gauge, substantially more resistance, and PoE runs on a voltage budget with very little slack in it.
A PoE source sits between 44 and 57 V. An 802.3at device needs at least 42.5 V arriving at its input. Everything in between is budget, and conductor resistance spends it. Across 90 m of pure copper there is margin left. The same run in copper-clad aluminium can push the device below its minimum, and the symptom is not a clean failure that points at the cable. It is a camera that boots, runs all afternoon, and reboots the moment the infrared illuminator switches on at dusk. Those faults are miserable to diagnose precisely because everything tests fine at noon.
Heat, in a Place You Cannot See
That same additional resistance becomes heat, inside a bundle, in a ceiling. It compounds the derating problem that dense PoE bundles already create, and it does so in the one location nobody inspects after the ceiling tiles go back up.
Brittleness at Every Termination
Aluminium work-hardens. Bend it at a punchdown, flex it behind a jack, and it fractures — sometimes immediately, more often weeks later. The result is an intermittent fault at a termination point, which is the worst category of network problem to chase because it comes and goes with temperature and vibration.
It Is Also Non-Compliant
TIA-568 specifies solid copper conductors. Copper-clad aluminium does not meet that specification, which has consequences beyond performance: it cannot form part of a certified channel, it will not carry a manufacturer's system warranty, and if a fire investigation ever examines the installation, non-listed cable in the pathway is not a conversation anyone wants to have with an insurer.
How to Spot It Before You Buy
Price far below the market is the first signal, and usually the only one you need. Beyond that, look for the letters CCA, the phrase copper clad, or a conspicuously missing conductor specification. Legitimate bulk cable states solid bare copper explicitly, because the manufacturer is proud of it. If a reel is already on site, strip an inch: copper is copper the whole way through, while copper-clad aluminium shows silver-white metal under the plating.
What the Savings Actually Are
The discount looks like twenty to forty percent on the reel. Set that against one callback with a lift, two technicians and a ceiling to reopen, and the arithmetic collapses immediately. Cable is the cheapest component in the install and the most expensive one to replace.
FAQ
Is CCA acceptable for non-PoE runs?
It is still non-compliant and still brittle at terminations. Without PoE the voltage-drop failure disappears, but the reliability and certification problems do not.
How do I know what I already have installed?
Check the jacket print, which usually names the conductor, and strip a spare tail. If existing runs are CCA and carrying PoE, prioritise the longest and most heavily loaded ones for replacement.
Do reputable brands sell CCA?
Some sell it clearly labelled for non-critical use. The problem is the unlabelled product sold as though it were equivalent to copper, which it is not.
Updated August 2026