I'm trying to decide what wire we should use when running new runs.

I was wondering what implications there might be to using CAT6 Copper Clad Aluminum wiring vs Pure Copper CAT5e.

I'm not sure if I could expect benefits from one over the other given the relatively short runs that I expect to have (10-100ft, or 3-30 meters).

The only plans I currently have for the wire are for ethernet use.

EDIT: I don't have any specific speed target other then to get as fast as I can with the given cable. My question spawned from reading a couple of things online stating that there can be heat issues from using CCA wiring, but it also looked like that was targeting installations surrounding power over Ethernet (cameras and such). I don't have any plans for this at the moment.

So I'm wondering if the tighter winding of cat6 CCA will perform better then looser winding of pure copper cat5e.

  • The answer to your question is "Use cabling rated for the data transfer speeds you are targeting". If you use cabling that is not rated for the application you may experience degraded performance (or things may work fine).
    – voretaq7
    Aug 25, 2012 at 22:14
  • It would also help to know what speeds you are targeting. 1Gb? 10Gb? 40Gb? Aug 26, 2012 at 3:05
  • @MarkHenderson See the updated question.
    – Jared
    Aug 26, 2012 at 3:40
  • 1
    "will perform better" <-- You've got a fundamental flaw in your reasoning here. There is no "better" or "worse". This is a digital system, it either works or it doesn't, there is nothing in between. This is the same logic that causes cheap HDMI manufacturers to go crazy when people pay extra for the "premium" Monster cables.... it's digital, it either works or it doesn't.
    – Chris S
    Aug 26, 2012 at 4:12
  • @ChrisS ...If speed is a measure of "better" then surely you aren't saying that cat5 vs cat6 are the same? While the wording might be incorrect when taken out of context I think the statements as a whole make it apparent as to what I'm asking.
    – Jared
    Aug 26, 2012 at 4:21

10 Answers 10


Including aluminum in conductors decreases cost for the manufacturer. If the cable meets the various specifications for impedance, crosstalk, etc and the cable is run within spec (bend radius, proximity to interference, strain) then the materials utilized for the conductor don't matter.

The physical difference between cat5e and cat6 has to do with the number of twists per inch and, potentially, the inclusion of shielding. The result of these changes is that the cable can (minimally) support higher bandwidth, specifically 10GE in this case. The other cable (5e) isn't rated to support these kinds of speeds but very well might work in practice.

If you're looking to future-proof for 10GE (or more) then go for 6a or 7. If you're just setting up basic 100M or GE then it doesn't make much difference. 5e and 6 are fairly close in price. The distances involved are quite low, which renders any difference theoretical at best. In summary? There won't be any practical benefit either way.

  • Does the information that I just added change any of this (looks like we were typing at the same time). Also last I looked Aluminum had something around 6x the impedance of copper. Is this a situation of the run being so short that this will have little to no consequence?
    – Jared
    Aug 26, 2012 at 3:42
  • Tighter wiring improves differential noise rejection but doesn't materially change impedance (which is where any difference in heat would come from). You're also correct that at the distances in question it's even less of an issue. The other thing is that the amount of wattage in use in PoE shouldn't create any appreciable amount of heat - even with many dozens of cables in conduit.
    – rnxrx
    Aug 26, 2012 at 3:53
  • fia-online.co.uk/pdf/Whites/wp-IAN002-01.pdf is the document I'm referring to (fyi)
    – Jared
    Aug 26, 2012 at 4:23
  • It should also be added that CCA cable presents a potentially dangerous scenario if you intend on using POE. CCA cable also does not meet any specifications. Since its tensile strength is much lower than pure copper, it also runs a much higher risk of damage while pulling and results in a higher cable failure rate.
    – Nilpo
    Jan 25, 2015 at 9:58

I may be behind the times, but in my world there is no such thing as CAT6 Copper Clad Aluminum wiring, or indeed Cat 5 or 5e. Copper Clad Aluminum (CCA) wire does not meet ANSI/TIA, ISO OR EN specifications and so should not be labelled as such.

CCA cable can be used for networks with only short runs and will work if expectations are not high. However, Aluminum corrodes on contact with air which results in lots of post installation problems. Also because of the higher resistance, CCA cable should not be used for Power-Over-Ethernet. It's OK for some applications but it is NOT CAT5 or CAT6 even if it says so on the box!


It has the following problems:

  1. It's very fragile. It appears that the conductors can break inside the jacket with no obvious damage to the jacket. Sometimes just attempting to remove the jacket will break the conductors.

  2. Insulation displacement connectors will likely pierce the copper plating and make contact with the aluminum, creating a weak spot where the wire will break and also creating a spot where the aluminum can corrode.

  3. It does not comply with NEC. The NEC requires the use of copper conductors for communications cable (except for coax, which often has a copper clad steel center conductor). As a result, it is an electrical code violation to install this cable where NEC rules apply.

  4. Apparently the fragile nature of CCA wire makes it difficult to maintain the pair geometry required for cat5e/cat6 performance during the manufacturing process.

Now for some real-world experience:

  1. About 150 feet of this CCA stuff was installed...allegedly cat5e cable.

  2. It would not link up at gigabit speeds so 100 meg was tried.

  3. It linked up at 100 meg.

  4. A few weeks later the link started flapping. Users complained. The BOSS asked what was going on.

  5. Attempts to re-terminate the cable to fix the link flapping resulted in no link at all...not even at 10 meg.

  6. Not until different pairs were tried did the link come back up.

  7. Due to the concerns that the cable would likely fail again, the CCA cable was replaced with real copper cable, which took the better part of a day.

  8. All because someone saved probably $40 by buying CCA cable.

So, should you use CCA cable?

IF you can answer yes to the following questions, I enthusiastically recommend that you use CCA cable:

  • Do you like random, unpredictable network failures?
  • Do you like re-doing things?
  • Do you like explaining to your boss or your users why the network failed?
  • Do you like working with cable with conductors that break at the slightest insult?
  • Do you like to save a few bucks now to spend hours later?
  • Do you like to be "penny wise, pound foolish"?
  • Is your time worth very little?
  • Do you need a pull-string to use for when you install the copper cable you should have used in the first place?

Aluminum oxidizes over time., depending of your specific environmental area - faster than you would like..... This is why Aluminum is no longer acceptable in electrical systems ( some exceptions apply ) I would not be using CCA for anything Ethernet ESPECIALLY if you intend on using POE ever.

  • 2
    Aluminium is extremely reactive, what happens is that when exposed to air it is almost immediately covered with a thin layer of aluminium oxide, which is hard and very impermeable (for reference, some gems like ruby are essentially aluminum oxide). And this isn't aluminium cable, it is copper clad aluminium. At the high frequencies involved the currents move along the surface. Besides, the cable is securely clad in plastic, and won't be laid outdoors either. So this answer is really a red herring.
    – vonbrand
    May 23, 2013 at 18:36

While you won't see any performance difference resulting purely from the choice of metal used, there is a potential problem at the terminations. Specifically, the types of terminations used on ethernet cables will break through the copper coating and the connection will be primarily to the aluminium.

Unfortunately, that will prove unreliable long term. The aluminium will corrod at the termination contact points and will give you problems. The salts produced by the corrosion may also attack the termination contacts themselves. You will then need to either re-terminate the ends or replace the cable. How long this will take to happen is dependent on many factors but could be anywhere from a few weeks in extreme circumstances to several years.

  • While I've read that Aluminum is "more" prone to corrosion then copper I haven't seen anything that talked about this being a concern. The information I've read stated that the oxide film that aluminum is prone to forming will reform almost instantly if the existing film is penetrated. Do you by any chance have any information to reference for this. Not out of doubt I'm just wanting to get everything I can as my last year of college classes for my undergrad are going to be primarily networking related classes.
    – Jared
    Aug 26, 2012 at 6:42
  • I assure you that it is a problem. I don't have a reference I can point you to, merely long experience with aluminium conductors and the precautions electricians take to avoid problems. You're correct that the corrosion layer will reform pretty quickly (not instantly, more like hours or days) and I can also tell you that aluminium oxide is actually a pretty good insulator, as any electroplater can testify to. Aug 26, 2012 at 11:34
  • Like I said I'm not doubting you. My question arises from lack of/limited knowledge on the subject.
    – Jared
    Aug 26, 2012 at 17:57
  • I disagree with the first statement. CCA does offer less performance than pure copper. CCA has higher attenuation properties which equates to packet loss and decreased network speeds especially on longer runs. I agree with the statement about long-term reliability.
    – Nilpo
    Jan 25, 2015 at 10:03

In the 1900's they used steel or aluminum conductor wires for mains and pretty much every other kind of wiring. But then as the amps/volts needs got higher they figured out steel & aluminum have too much resistance compared to copper (more resistance = more friction as electricity moves through center conductor = hot wires). Ever seen the movie "A Christmas Carol" where the dad has everything daisy-chained/power-stripped from one plug? That house had the old "knob and tube" style wiring which the NEC outlawed from new builds in the 1970's. In other words steel and aluminum conductors for just about any voltage wiring (not just low voltage) has not been permitted for safety, functionality, and performance reasons for over 40 years. Only recently with the price of copper being so high, are some shady, unsafe manufacturer's bringing it back (Looking at you China). Also aluminum corrodes (grows a white powdery residue) wherever the connections are exposed to the air such as at the socket or breaker/fusebox. Same is true when used in communication wires at the punch down blocks. Also aluminum has 40% more resistance/impedance than copper meaning more packet loss = more re-transmitted packets = more errors = less throughput than copper. Certified CAT 6 is rated for 500MHz bandwidth. No way CCA can support that bandwidth, I'd love to share CCA bandwidth rating as a comparison but CCA has no ratings. Using CCA the higher frequencies will travel along the copper skin of the conductor only, and can't achieve same bandwidth as a pure copper center conductor. Also shorter cable runs are needed than copper. So I'd just half the regular CAT X certified distance rating of the cable to figure out likely CCA cable distances. For me at least, CCA effectively loses any benefits of upgrading in the first place either from CAT5 copper to CAT5e CCA, or from CAT5or5e copper to CAT6 CCA. Also I am using those terms loosely because CCA can't legally be called CAT 5, CAT 5e, or CAT 6 since it meets none of the UL, RoHS safety laws, or TIA/EIA data transfer specs.


Stay well clear of CCA any of it, its totally useless it has a 40% higher resistance than pure copper and like every one says it does not meet the TIA/EIA standards. BT used aluminium cabling in the 60s fine for 3khz voice path, but when ISDN and ASDL came alone it wouldn't work, hence BT had to upgrade its infrastructure. Used CCA once for CCTV transmission signal and power degraded after about 20 meters


For those commenting about the skin effect:

I tested some of this CCA cat5e stuff for attenuation. At frequencies up to 20MHz (my tester won't go beyond 20MHz, it's old), it tests as equivalent to cat3 for attenuation. This is based on db loss per foot.

So this cable not only doesn't meet the DC resistance specs for cat5e, it doesn't meet the attenuation specs either. The skin effect seems to not help.

This cable is (claimed) 24AWG.

I've also run across 26AWG "cat6" CCA cable. It's also marked on the jacket with a 30V rating, maybe that's their way of saying "Don't use this garbage for POE!"

That 26AWG CCA cable is, interestingly enough, UL listed..as AWM, appliance wiring material. That UL listing does not allow it to be installed in a building, as a cable must be listed as CM/CMG/CMX/CMR/CMP.

AWM is for internal wiring of appliances. I think someone found a loophole to claim that their CCA cable is UL listed..it is, but not for how it's actually going to be used.


CCA is not Category networking cable, no matter what the box you got it in or the printing on the sheathing claims. First of all, it has a much lower tensile strength than solid or braided pure copper, and the conductors will tend to break when the cable is being pulled for drops, punched down in jacks, or crimped into RJ-45 ends. On top of this, aluminum oxidizes all to readily on contact with air, so if you avoid conductors breaking, after a relatively short time, the exposed aluminum on the ends of the conductors where you clip the cabling to make a patch cable, a drop, or punch down to a jack, will degrade until the oxidation gets past where the conductors are punched down or crimped into the RJ-45 end, creating connectivity issues. Last but not least of the issues with the material itself is the issue of impedance. Because the impedance of CCA is so much higher than solid or braided pure copper, it is useless for Power over Ethernet (PoE) applications over any significant distance.

Finally, any box of CCA that claims it meets any standards, such as UL standards, is lying. This is the most egregious part of the CCA farce. UL standard 444 alone makes and CCA UTP cabling not standards compliant, as it is a safety standard, meaning that CCA UTP cabling is in nowise certified for use in walls. It fails to meet other certifying authority standards as well. Just don't use it. It's garbage.


I have found this thread most interesting.. Some of the history is just wrong others parts misleading or incomplete. Now with that said, Ethernet is not electrical cable nor analog telecommunication wiring, it carries a digital signal. It is twisted wire (24-23 ga). More twist less x-talk. Clad wire has been around for over a hundred years and as noted it's still being used today (UL listed).

The problem with CCA today is physical not electrical. Electrons flow on the surface (stranded wire has more surface). Punch down, quick connectors and tight bends in individual wires at connecting points are CCA's weak point. Also cheap connectors, the ones that spring apart when punched down but don't return to original position when released and maintain pressure on the connection (loose or open connection). All these are enemies of aluminum, plus add vibration and metal migration. I have have seen at lot in my 48 years in telecommunications. Y'all newbies have being given a great starting point for moving communications to the next level. You remember "number Please"?

So my advice is: use copper and only the best connectors. At home for a small LAN, well money is tighter there.

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