What Ethernet cable categories mean and why they matter
Every Ethernet cable is assigned a category rating that defines its minimum performance: how much frequency it can carry (measured in MHz), the maximum data rate it supports (measured in Mbps or Gbps), and the maximum distance over which it can reliably deliver that performance. Higher categories use tighter conductor twists, stricter manufacturing tolerances, and in some cases individual pair shielding to achieve their ratings.
Understanding the category system matters for three reasons. First, every component in a cabling link must meet the same category rating for the link to be certified at that level. A Cat6a cable terminated into a Cat5e keystone jack performs as Cat5e. Second, some categories are TIA/EIA-recognised standards with full AU compliance pathways under AS/CA S008, and some are not. Third, the category determines whether a cable is safe and suitable for Power over Ethernet (PoE) applications, which affects every access point, IP camera, VoIP phone, and smart building device on the network.
This guide covers every category from Cat1 to Cat8, with AU-specific context throughout. For a deep comparison of the two categories most relevant to new Australian installations, see our Cat6 vs Cat6A guide. For shielding selection (UTP, F/UTP, S/FTP), see our Cable Shielding Guide.
Ethernet category standards: full reference table
Bandwidth (MHz) and data rate (Gbps) are related but different. Bandwidth describes the frequency range the cable can carry cleanly. Data rate is the throughput your equipment can achieve over that bandwidth using its encoding scheme. A higher MHz rating does not automatically mean a proportionally higher data rate. Maximum distance figures apply at the stated maximum data rate; most categories support longer runs at lower speeds.
| Category | Max bandwidth | Max data rate | Max distance | Typical use | AU relevance |
|---|---|---|---|---|---|
| Cat1 | 0.4 MHz | 1 Mbps | Not defined | Analogue voice, ISDN | Legacy only. Not permitted for data cabling under AS/CA S008. |
| Cat2 | 4 MHz | 4 Mbps | Not formally specified | Token Ring, older PBX | Legacy only. No TIA/EIA formal standard exists for Cat2. |
| Cat3 | 10 MHz | 10 Mbps | 100 metres | 10Base-T Ethernet, voice | Still found in older AU buildings. Not suitable for new data installations. |
| Cat4 | 20 MHz | 16 Mbps | 100 metres | Token Ring 16 Mbps | Legacy only. Occasionally found in older manufacturing or government sites. |
| Cat5 | 100 MHz | 100 Mbps | 100 metres | Fast Ethernet (100Base-TX) | Obsolete. Superseded by Cat5e. Do not specify for new work. |
| Cat5e (Class D) | 100 MHz | 1 Gbps | 100 metres | Gigabit Ethernet, standard PoE | Still valid for low-density residential and retrofit work. Not recommended for PoE++ (802.3bt). |
| Cat6 (Class E) | 250 MHz | 1 Gbps (100m) / 10 Gbps (55m) | 100 metres at 1 Gbps; 55 metres at 10 Gbps | Gigabit and short-run 10GbE, PoE and PoE+ | Suitable for most AU residential and small commercial work. Specify Cat6a for any new commercial installation requiring 10 Gbps at full distance. |
| Cat6a (Class Ea) | 500 MHz | 10 Gbps | 100 metres | 10GbE, PoE++ (802.3bt), Wi-Fi 6/6E/7 uplinks | Recommended standard for all new AU commercial installations. Fully AS/CA S008 compliant. |
| Cat7 (Class F) | 600 MHz | 10 Gbps | 100 metres | Specialist/proprietary only | Not a TIA/EIA-recognised standard. Not recommended for AU structured cabling. See note below. |
| Cat7a (Class Fa) | 1,000 MHz | 10 Gbps (100m) / 40 Gbps (50m) / 100 Gbps (15m) | 100 metres at 10 Gbps | Specialist/proprietary only | Not a TIA/EIA-recognised standard. Not recommended for AU structured cabling. See note below. |
| Cat8 (Class I/II) | 1,600 to 2,000 MHz | 25 to 40 Gbps | 30 metres at 25/40 Gbps; 100 metres drops to 10 Gbps | Data centre switch-to-switch connections | TIA-recognised. For data centre use only. Not a general-purpose upgrade over Cat6a. |
Legacy categories: Cat1 to Cat4
Categories 1 through 4 predate structured data cabling standards as we know them today. None are suitable for new installations and none are covered by the current AS/CA S008 standard for compliant customer cabling products in Australia.
Cat1 was used for analogue telephone wiring and ISDN connections. It was not twisted pair in the modern sense and was never rated for data. Cat2 followed for Token Ring networks at 4 Mbps and was primarily an IBM-era standard with no formal TIA/EIA specification. Cat3 was the first category to support 10 Mbps Ethernet (10Base-T) and introduced the four-pair twisted pair construction still used today. It is still found in older Australian office buildings and schools where the cabling has never been replaced. Cat4 extended Token Ring to 16 Mbps and was the first category to use the RJ45 connector.
If you encounter Cat3 or Cat4 wiring in an existing building and need to run Gigabit Ethernet on those runs, the cable must be replaced. No amount of re-termination will bring a Cat3 run up to Gigabit performance.
Current categories: Cat5e, Cat6, and Cat6a
These three categories cover virtually every new structured cabling installation in Australia today.
Cat5e: still valid, with limitations
Cat5e (enhanced Category 5) improved on Cat5 by tightening the twist rate and crosstalk specifications, enabling Gigabit Ethernet (1000Base-T) over 100 metres. It remains a compliant and cost-effective choice for low-density residential work and retrofit jobs where conduit cannot accommodate the larger diameter of Cat6a. The critical limitation is PoE. Cat5e uses 24 AWG conductors, which generate more heat under sustained power load than the 23 AWG conductors in Cat6 and Cat6a. For any installation running 802.3bt (PoE++) devices such as Wi-Fi 6 access points, IP cameras, or smart building sensors, Cat5e is not recommended.
Cat6: the residential and small commercial workhorse
Cat6 doubled the bandwidth ceiling to 250 MHz and introduced a plastic spline separator between conductor pairs to reduce crosstalk. It supports 10 Gbps, but only up to 55 metres under ideal conditions. In real-world installations with bundled cables in trays and longer patch lead runs, this effective distance is often 37 to 45 metres. Cat6 uses 23 AWG conductors, which gives it meaningfully better PoE performance than Cat5e. It is a solid choice for residential installs, small office fit-outs, CCTV, point-of-sale, and voice runs where 10 Gbps at full distance is not required.
Cat6a: the recommended standard for new AU commercial installations
Cat6a (Augmented Category 6) doubles the bandwidth ceiling again to 500 MHz and adds alien crosstalk (ANEXT) specifications that allow 10 Gbps to run reliably at the full 100 metres regardless of bundling conditions. It uses 23 AWG conductors and is the minimum recommended category for 802.3bt PoE++ deployments. The installed cost premium over Cat6 is typically modest relative to total project labour, and the performance headroom future-proofs the installation against Wi-Fi 7 access point uplink requirements, 2.5 GbE and 5 GbE multi-gigabit switches, and the next generation of IP cameras and building management systems.
For new commercial installations in Australia, Cat6a is the correct specification unless there is a specific reason to do otherwise (such as a retrofit where existing conduit cannot accommodate Cat6a's larger outer diameter). See our Cat6 vs Cat6A guide for a full decision framework including pricing.
Specialist categories: Cat7, Cat7a, and Cat8
Cat7 and Cat7a: why you should not specify these for standard AU work
Cat7 and Cat7a are ISO/IEC standards, not TIA/EIA standards. This distinction matters enormously in practice. The TIA (Telecommunications Industry Association) and EIA are the bodies whose specifications underpin structured cabling certification in Australia and most of the world. Cat7 and Cat7a were developed by a separate consortium and require GG45 or TERA connectors, not standard RJ45.
The problem is that virtually all Cat7 cable sold in Australia comes with RJ45 connectors. A Cat7 cable with RJ45 connectors cannot be certified to the Cat7 standard because the connectors do not meet it. When tested with a Fluke certifier against TIA specifications, that cable will be assessed against Cat6a, not Cat7. You pay a premium for Cat7 labelling and receive Cat6a performance at best.
Cat7 and Cat7a are not referenced in AS/CA S008 as recognised categories for compliant customer cabling. For any structured cabling job in Australia that will be commissioned and certified, specify Cat6a. It delivers the same 10 Gbps at 100 metres, uses standard RJ45 connectors, and can be certified.
Cat8: data centre only
Cat8 is a genuine TIA-recognised standard (ANSI/TIA-568-2.D) and is the legitimate successor to Cat6a for specific applications. The key qualification is "specific." Cat8 supports 25 Gbps and 40 Gbps, but only up to 30 metres. Beyond 30 metres, Cat8 falls back to 10 Gbps performance, the same as Cat6a. This makes Cat8 suitable exclusively for short switch-to-switch and server-to-switch connections inside data centres and equipment rooms. It is not a general-purpose upgrade for horizontal cabling runs in office buildings or campuses. If a salesperson or supplier recommends Cat8 for a standard commercial fit-out, the correct question is why, because Cat6a delivers identical real-world performance in that environment at lower cost.
What about Cat5, Cat6e, and other non-standard labels?
Cat5 (not Cat5e) is obsolete and has been superseded since the late 1990s. It is no longer manufactured and should never be specified.
Cat6e does not exist as a recognised standard. It is a marketing label used by some manufacturers to describe cable they claim is better than Cat6 but below Cat6a. There is no TIA/EIA or ISO/IEC Category 6e specification. Cable sold as Cat6e cannot be tested or certified against any formal standard. If you encounter Cat6e on a specsheet or quote, treat it as Cat6 at best.
Similarly, "Cat7 RJ45" is a contradiction in terms. As noted above, true Cat7 requires GG45 connectors. Cable sold as Cat7 with RJ45 connectors is effectively Cat6a cable with a misleading label.
PoE compatibility by category
Power over Ethernet delivers data and electrical power over the same cable simultaneously. The IEEE 802.3 PoE standards have evolved significantly in power output, and cable category plays a direct role in safety and performance, particularly for higher-power applications.
| PoE standard | Max power (at switch port) | Minimum cable category | Recommended category | Typical AU devices |
|---|---|---|---|---|
| 802.3af (PoE) | 15.4 W | Cat5e | Cat5e or Cat6 | IP phones, basic IP cameras, access control readers |
| 802.3at (PoE+) | 30 W | Cat5e | Cat6 | Wi-Fi 5 access points, PTZ cameras, video phones |
| 802.3bt Type 3 (PoE++) | 60 W | Cat5e (not recommended for bundled runs) | Cat6a | Wi-Fi 6/6E access points, high-resolution IP cameras |
| 802.3bt Type 4 (PoE++) | 100 W | Cat5e (not recommended) | Cat6a (mandatory for bundled runs) | Wi-Fi 7 access points, digital signage, smart building sensors, laptop charging |
The reason Cat6a is recommended for 802.3bt is conductor size and heat dissipation. Cat6a uses 23 AWG solid copper conductors versus the 24 AWG in Cat5e. Thicker conductors have lower DC resistance, which means less heat is generated when sustained current flows through them. In a cable tray carrying dozens of PoE++ runs, Cat5e bundles can reach dangerous temperatures that degrade insulation and reduce cable lifespan. Cat6a handles the thermal load safely. Shielded Cat6a (F/UTP or S/FTP) dissipates heat even more efficiently than UTP due to the metallic shield providing an additional conduction path along the cable.
One critical note for all PoE installations in Australia: only solid copper cable (never CCA, copper-clad aluminium) is permitted under AS/CA S008. CCA cable has approximately 40% higher resistance than solid copper, which causes dangerous overheating under PoE loads. See our CCA cable guide for the full compliance and safety picture.
Which category for new Australian installations?
For the vast majority of new structured cabling work in Australia, the decision is straightforward.
Specify Cat6a for all new commercial fit-outs, education, healthcare, hospitality, and any installation that will carry 802.3bt PoE++ devices. Cat6a is the current TIA-recommended standard for new structured cabling, it is fully covered under AS/CA S008, it supports 10 Gbps at 100 metres without qualification, and it handles the PoE++ current loads that modern Wi-Fi, camera, and building management infrastructure increasingly demands.
Specify Cat6 for residential, small office retrofit, CCTV at standard PoE levels, and any job where conduit sizing or budget genuinely precludes Cat6a. Cat6 remains a fully compliant and capable choice for these applications.
Do not specify Cat5 (obsolete), Cat6e (not a real standard), Cat7 with RJ45 connectors (cannot be certified), or Cat8 for horizontal runs (data centre application only).
Browse our stocked range: Cat6 cable and Cat6a cable, all solid copper, AS/CA S008 compliant, backed by a limited lifetime warranty.
Frequently asked questions
What is the difference between bandwidth (MHz) and data rate (Gbps)?
Bandwidth in MHz describes the frequency range a cable can carry without significant signal degradation. Data rate in Gbps describes the actual throughput your network equipment achieves over that cable. A higher MHz rating creates headroom for faster encoding schemes and better noise rejection, but the relationship is not linear. Cat5e and Cat6 both have a 100 MHz bandwidth ceiling but Cat6 supports 10 Gbps at short distances because its tighter construction and better crosstalk rejection allow more efficient signal encoding. Cat6a at 500 MHz supports 10 Gbps at full 100 metre distance because it adds alien crosstalk specification that Cat6 lacks.
Can I mix cable categories in the same installation?
Every link in a structured cabling system is rated at the lowest category component in that link. If you run Cat6a cable but terminate it into Cat5e keystones and connect it to a Cat5e patch panel, the link will be certified as Cat5e. For a link to be certified at Cat6a, every component including the cable, keystones, patch panels, and patch leads must meet the Cat6a specification. This is why specifying everything to the same category from the start is far more cost-effective than trying to upgrade incrementally later.
Is Cat7 worth buying in Australia?
No, for standard structured cabling work. Cat7 requires GG45 connectors to meet its standard, but virtually all Cat7 cable sold in Australia uses RJ45 connectors. A Cat7 cable with RJ45 connectors cannot be certified to Cat7 because the connectors do not comply with the Cat7 specification. When tested against TIA standards, it will be assessed as Cat6a at best. You pay more for the Cat7 label and receive no benefit. Specify Cat6a instead. It delivers identical real-world performance, uses standard RJ45 connectors, and can be properly certified.
Is Cat8 suitable for office or commercial building installations?
No. Cat8 supports 25 to 40 Gbps, but only up to 30 metres. Beyond 30 metres it performs identically to Cat6a at 10 Gbps. Its design purpose is short data centre connections between switches and servers within the same equipment room. For horizontal cabling runs in offices, schools, hospitals, or any building where runs exceed 30 metres, Cat8 provides no benefit over Cat6a and costs significantly more.
What is the minimum cable category required for PoE++ (802.3bt)?
Technically Cat5e meets the minimum electrical requirements for 802.3bt up to 100 W, but it is not recommended for bundled runs because the 24 AWG conductors generate more heat under sustained load than 23 AWG Cat6a. Best practice for any 802.3bt installation in Australia is Cat6a. The additional cost per drop is modest, and the thermal performance improvement is significant in cable trays with multiple PoE runs. For high-density installations such as open-plan offices with Wi-Fi 6 or Wi-Fi 7 access points, Cat6a is effectively mandatory to keep cable temperatures within safe limits.
What does AS/CA S008 mean for cable selection?
AS/CA S008 is the Australian standard for customer cabling products, adopted by the ACMA as the mandatory technical standard under the Telecommunications (Cabling Provider) Rules 2025. All customer cabling work in Australia must use products that comply with AS/CA S008. In practice this means solid copper conductors (CCA is prohibited), tested and labelled products from compliant manufacturers, and installation by registered cablers. Cat5e, Cat6, Cat6a, and Cat8 all have pathways under AS/CA S008. Cat7 and Cat7a do not, which is an additional reason not to specify them for AU structured cabling work.
Does backward compatibility work both ways?
Cat6a, Cat6, and Cat5e equipment are all backward compatible downward. A Cat6a switch port will work with a Cat5e patch lead. A Cat6 keystone will accept a Cat5e plug. However, the link always performs at the lowest rated component. Backward compatibility means equipment will function, not that it will perform at the higher category's rating. Upgrading to Cat6a cabling while keeping Cat5e patch leads means your links certify as Cat5e. Replace all components to realise the Cat6a performance you paid for.
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