Why Cat8 Is Likely a Waste of Your Money

Written by Don Schultz, Senior Technical Marketing Specialist, Fluke Networks Certified Copper/Fiber CCTT, BICSI TECH, INSTC, INSTF Certified

Cat8 is the most heavily marketed and least practically useful cable category on the consumer market. Yes, on paper the specifications of 2 GHz and up to 40 Gbps seem quite impressive. The question is if you can leverage those specifications and is it even practical to try? Let’s save you the buyer’s remorse and find out if Cat8 is worth it.

Please watch the above video and then continue reading this blog. The video and blog are complimentary to each other -- both bring something to the table.

What Is Cat8, and What Can It Actually Do?

Cat8 is a category of copper twisted pair Ethernet cable that was introduced in 2016 with the ANSI/TIA 568-C.2-1 revision to the original ANSI/TIA 568-C.2 document. Cat8 adoption was then incorporated into the full standard as of the ANSI/TIA 568.2-D revision.

Cat8 was developed to address short distance high speed LAN equipment connections in data centers and server rooms. Typically, Cat8 is used for switch-to-switch or switch-to-server high speed applications using 25G or 40G over copper — a niche rapidly being replaced by fiber and SFP module-based switching.

The following unique characteristics separate Cat8 from previous categories of Ethernet cable:

• 2 GHz bandwidth support*
• Capability of handling 25GBASE-T and 40GBASE-T application speeds*
• Requires Cat8 rated termination hardware
• Cat8 is typically shielded (S/FTP or F/FTP) and uses 22 AWG conductors, though TIA does not specifically require it
• Critical limitation: Cat8 can maintain 2 GHz and up to 40 Gbps application speeds to a maximum of 30 meters (~100 feet) channel length which includes a 79 foot permanent link and 21 feet total combined patch cords. Beyond the maximum (performance induced) channel length limit of 100 feet, Cat8 drops back to Cat6A-equivalent performance (10GBASE-T) and may be used for 10GBASE-T applications up to an absolute maximum of 328 feet (100 meters).

Cat8 channels are constructed the same way as Cat6A, just a lot shorter!

Beyond the performance requirements and limitations, Cat8 is still built using the typical components you would see in Ethernet cable:

• Eight pure copper 22 to 24 AWG insulated conductors, that must not exceed 1.64mm insulated conductor diameter, twisted into four color coded circuit pairs (blue, orange, green, brown)
• Outer thermoplastic flexible cable jacket that must not exceed 9.0mm overall diameter
• Cat8 is terminated using the T568A or T568B color code scheme
• Like previous categories, conductor untwist maximum at the terminations remains 0.50”

Typical Cat8 cable, making use of 22 AWG solid copper conductors with S/FTP shielding. This is a very thick cable, approaching the 9.00mm TIA limit.
Image courtesy of The Home Depot

Why Cat8 Is the Least Useful Cable Category

Clearly there is a major limitation we are dealing with here--100 feet maximum length at the higher advertised speed capability. The 100-foot (30m) channel length ceiling means Cat8 can't be used for most structured cabling runs in a home or commercial building, where the ANSI/TIA 568 standard allows up to 328 feet (100m) for Cat6A. At home network speeds — even 10Gbps — Cat8 provides zero additional benefit over Cat6A.

Here are some additional facts and trends that make Cat8 not very useful:

• Implementation of 25G and 40G over copper in a traditional LAN switch is extremely expensive and often found only in the highest-end niche LAN hardware -- far out of reach of all but the largest enterprise budgets.
• Modern data centers have largely moved to fiber optic for switch-to-switch and server connections — the exact use case Cat8 was built for. New enterprise switching equipment overwhelmingly uses SFP+ or SFP28 modules with fiber, not 25/40G copper.
• Fiber optical transceiver capability (SFP ports) is common in “prosumer” networking equipment and becoming increasingly common in mass market consumer equipment. Fiber optic cable goes a lot farther and a lot faster. Conveniently, fiber also happens to be immune from EMI/RFI and higher ambient temperatures.
• As mentioned previously, Cat8 is often shielded and will require bonding to ground, greatly increasing installation cost and complexity.
• Cat8, like any thick shielded copper Ethernet cable, is going to be stiff and weigh quite a bit. Picture “frozen garden hose” in your mind and you will have an idea of what it is like to deal with Cat8. This adds additional strain to your structured cabling system support hardware (not to mention your back, too).
• Often installing Cat8 will require specialty Cat8 rated terminations. Given that Cat8 is typically using multiple forms of shielding and 22 AWG conductors, it is difficult if not impossible to terminate it with 8P8C (aka RJ45) connector plugs. You would not want to try anyway, unless you like frustration.

What does this all add up to? Well, quite frankly, Cat8 is the least useful Category cable. Unless you have a specific use case for it that makes sense and nothing else but Cat8 will do, don’t bother.

What Should You Use Instead?

So, what alternatives do you have for high speed cabling and what should you use where? Keep in mind that most installations are going to be hybrid in nature, where fiber optical cable and traditional copper twisted pair Ethernet category cable compliment each other. The trick is knowing what is best used where and what the decision trigger points are, which we will cover in detail right now!

Cat6A — The Right Answer for Most Copper Drops

trueCABLE’s Cat6A Riser Ethernet Cable｜Unshielded cable

Consider your installation holistically. If you seek to future proof your installation for 10GBASE-T (10 Gbps speed), or already know you need that speed, you are already at the decision point between copper and fiber. Cat6A handles 10G quite well and is a very valid choice. Cat6A handles all previous speeds without issue, so you can install it now and grow into it as your needs grow.

• Supports 10GBASE-T all the way to 328 feet (100m) channel length — the full TIA-568 allowance.**
• 10 Gbps is the practical ceiling for copper Ethernet in home and many commercial environments.
• Cat6A will be future-proof for at least the next 10–15 years of consumer and small business networking needs.
• Sure, Cat6A cannot do 25G or 40G — but neither can your home network, router, or switch.
• Cat6A is available in a dizzying array of high quality options, with outdoor and direct burial versions plus fire resistance plenum versions easily found. Economies of scale have reduced the price point of Cat6A significantly.
• Cat6A, like any copper twisted pair Ethernet cable, handles Power Over Ethernet needs where fiber optical cabling cannot. As it turns out, glass does not conduct electricity very well…

A large caveat regarding copper Ethernet cable length is ambient temperature. The maximum 328 foot channel length is assuming 68℉ or less ambient temperatures. If your ambient temperatures are higher than that, you must de-rate (shorten) your drop length.

For practical and easy to understand advice on how far you can push your copper Ethernet cable channels please see Temperature's Effect on Ethernet Cable Length and you will also likely find Calculating Ethernet Cable Overall Channel Length for Success quite useful!

Don’t forget about good old Cat6. Many home networks won’t need speeds higher than 5 Gbps any time soon and Cat6 provides that out to 328 feet, too. Oh, and Cat6 tends to be easier on the wallet if that is a concern.

Fiber Optic — When Your Needs Exceed Copper

As I mentioned, Cat8 is the “decision point” between copper and fiber. The reason is that for all practical purposes, any contemplation of application speeds above 10 Gbps should be addressed by fiber optical cable. Other decision points that trigger the switch to fiber are:

• Ambient temperatures (like outdoor or factory environments) so high you cannot make the connection as outlined by the limits in Temperature's Effect on Ethernet Cable Length
• Lengths that exceed the 328 foot (100 meter) hard limit regardless of ambient temperature and regardless of application speed needs
• Extremely high EMI/RFI environments where separation distance and shielding from the EMI/RFI are not sufficient

Fiber optical cable has a lot of advantages over traditional copper cabling, such as:

• EMI/RFI immune — completely unaffected by electrical interference
• Immune to high ambient temperatures
• Dramatically smaller cable bundle compared to Cat8 — easier to route in tight conduit
• Supports much higher speeds over greater distances than any copper category
• Fiber is the current standard for backbone runs and switch-to-switch connections in data centers
• Lighter than Cat8 and carries more data

Here is a quick comparison table:

The trueCABLE Recommendation

For virtually every home and small business installer, Cat6A gives you everything you need from copper. You can push your LAN speeds to 10 Gbps and still have the ability to power remote devices like WiFi access points and surveillance cameras with PoE. If your requirements push beyond 10G or your runs are exceptionally long, move to fiber — not Cat8.

Conclusion

Cat8 is a real category with real use cases, but most environments won’t benefit from it. The use case for Cat8 is small and shrinking, and certainly does not include your home, nor your small office, and probably not anywhere you're likely to install cable. Buy what you actually need: Cat6A for copper drops, fiber for anything beyond that.

HAPPY NETWORKING!

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