I'm in the process of switching my smart home over to Power-over-Ethernet, and I've noticed that one of the network wiring tips that should be a given was missed off the list. It should be a given when you're handling power delivery over thin wires, and it is technically covered by the "Category" cable specifications, but it deserves a highlight of its own.

There are two types of twisted-pair cable that are sold for home use, or maybe I should say two material types, because there's a whole range of "Category" cables. There's pure copper cabling (which you want) and copper-clad aluminum (CCA) cables, which you do not want under any circumstances. There is a whole litany of why you don't want CCA cabling, but the quick version is that it isn't to standards, putting you or your installer in legal hot water. Plus, it's a significant safety hazard, so let's find out why.

The quality of your network cables matter

More so than for data transfer, really, since you're passing power too

When running wired backhaul to each room in your home, the costs involved add up pretty quickly. There are tools, cabling, conduit (if you're doing it properly), connectors, and many other things before you consider labor costs and any potential repairs to drywall and paint. It's all too easy to want to trim that budget before it creeps up to more than you expected, but the one place you should not skimp is on the quality of the cable you are putting into your walls.

This is going to be the highway that data is transferred over your home network, and the low-voltage power delivery method for access points, IP cameras, lighting, and about a dozen other potential devices that can use PoE. It deserves quality. Your home deserves quality. But even more so, your home deserves safety and that's not what you will find if you buy copper-clad aluminum cabling.

You don't want to create heat sources inside your walls

Every time you're transmitting power over wires, you have the potential to cause heat. When the power in watts increases, so does the potential for unwanted heat, and that's a problem for any twisted-pair communications cabling. It was a problem when PoE topped out at 15.4W or 30W, but it's even more of a problem now that you can power devices with PoE at 95W.

High-performance Wi-Fi 7 access points, PTZ cameras or some thin clients could all pull over 60W individually. To accommodate this, the IEEE increased the cabling requirements from two pairs to four pairs, but that also means a greater likelihood of dangerous cable overheating, especially on copper-clad aluminum cables which have 55% more electrical resistance than pure copper conductors.

CCA cables are prohibited from being used in many buildings, because they're not up to modern safety standards and can cause overheating, fires, or toxic smoke. They lack flame-retardant properties that other in-wall cables are supposed to have.

Any CCA cables that say they're rated are lying

I'll say it once — copper-clad aluminum cabling is junk

The tricky thing with CCA cables is that you might not have any indications that it's not pure copper. The cable sheathing could look right, have UL listing marks, and other certification stamps, making your job harder. But you know what you can look at? The price.

Pure copper twisted-pair cabling, like that used in "Category" cables for networking use, is a known quantity these days. It's been around for a long time, it's made in the same factories, no matter which brand you buy, and the raw materials pricing is fairly stable. If you see two 200ft spools of Cat6a cable for sale, and one spool is significantly cheaper than the other, don't buy the 'bargain.' It will absolutely come back and haunt you, because there's a good chance that cut-price cable is counterfeit.

The safety standards markings could be fake. It could be a thin layer of copper over an aluminum core. It could be using plastic sheathing that's not fire-resistant. Whatever the potential issues, they are not worth the cost savings.

It's also not good for your data signals

Whether your twisted-pair cabling passes PoE and signals over two or four pairs, it uses a common-mode voltage, so the current splits evenly between the number of conductors. Any imbalance distorts the data signals, as the equipment on each end assumes that data going over the same-length wires will take the same amount of time to travel.

When metal heats up, it becomes more resistant to current, as while the electrons are still free to move, the crystal lattice vibrates more thanks to the higher amount of energy in the metal. That's (mostly) okay if all of your data pairs are heated at an even rate, but when unbalanced heating happens, you can get bit errors, retransmits, non functioning data links, or the PoE handshake can be lost, powering down whatever device you have on the other end. It's a pain to troubleshoot; the best defense is to put good-quality cables in when you first pull wiring.

My PoE network deserves quality cables with all-copper conductors

It might be less common nowadays, but you should always steer clear of copper-clad aluminum twisted-pair cabling, whether you're planning on using PoE or not. It's less durable, more likely to break when put under strain, and is a false economy because pulling the cables is the expensive part of any installation, and you don't want to have to pull it again if part of the network becomes faulty. Plus, it's not upt to National Electrical Code, UL 444, or TIA standards for communications cabling, because it's a fire hazard. Don't put it in your home, let alone in your walls.