Cat5 vs Cat6: What Is the Difference?

Cat5 vs Cat6 is a comparison of two grades of twisted-pair Ethernet cable defined in the TIA-568 cabling standard. The category number states the frequency the cable is tested to and how well it controls crosstalk between its four pairs. A higher category supports a higher data rate over the same distance.

Original Cat5 is now obsolete. It was tested to 100 MHz for Fast Ethernet, and Cat5e (enhanced) replaced it in 2001 with tighter crosstalk limits that make gigabit Ethernet reliable. In practice, any “Cat5” cable sold today is Cat5e, so the real comparison is Cat5e against Cat6 and Cat6A.

Cat6 raises the test frequency to 250 MHz. It typically uses slightly thicker 23 AWG conductors, tighter twists and often a plastic spline that holds the pairs apart. Those changes cut crosstalk enough to carry 10GBASE-T over shorter runs.

The table sets out the categories you are likely to meet, with the Ethernet speeds IEEE 802.3 defines for each over twisted pair.

Cat7 and Cat7A appear in the ISO/IEC 11801 standard rather than TIA-568 and were designed around different connectors, so most installers move from Cat6A straight to Cat8. Reach figures for Cat6 at 10 Gb/s vary with how tightly cables are bundled, because neighboring cables add alien crosstalk.

Cat6A (augmented) doubles Cat6’s test frequency to 500 MHz and adds limits on alien crosstalk between cables. That is what lets 10GBASE-T run the full 100 m. The cost is size: Cat6A is noticeably thicker and stiffer, so it needs more space in trays and a larger bend radius.

Choose Cat6A where links carry, or will carry, 10 Gb/s over more than around 50 m, where access points use multi-gigabit uplinks, or where large bundles carry high-power PoE. Our overview of multi-gig speeds and the cabling they need covers 2.5 and 5 Gb/s links on existing cable.

Power over Ethernet sends current down the same pairs that carry data, and some of that power is lost as heat in the cable. Thicker conductors lose less, so Cat6 and Cat6A run cooler than Cat5e when many PoE cables are bundled together. IEEE 802.3bt Type 3 and Type 4 PoE, which deliver up to around 60 W and 90 W at the source, are specified for Cat5e or better, but Cat6A is the usual choice for large bundles. Our guide to industrial Power over Ethernet covers power classes and budgets.

The right category depends on the speed the link needs today, the speed it may need during the life of the installation, and how hard it is to re-cable later.

• Keep existing Cat5e for gigabit desks, cameras and sensors, and for 2.5 Gb/s upgrades. Most Cat5e runs in good condition carry 2.5GBASE-T without change.
• Install Cat6 for new general-purpose runs where gigabit is the target and 10 Gb/s would only ever be needed over short distances.
• Install Cat6A for backbone links, multi-gigabit access point uplinks, vision systems that stream from several high-resolution cameras, and any run that will be expensive to replace.
• Use fiber beyond 100 m, between buildings, or where earth potential differences and lightning risk make copper a liability.

Whatever the category, the whole channel has to match it. A Cat6A cable terminated with Cat5e jacks or patch leads performs as Cat5e, so specify the plugs, jacks and patch panels to the same category as the cable.

On factory floors, vehicles and outdoor cabinets, the jacket, shielding and connector often matter more than the category.

We fit the network interfaces, switch ports and connectors each installation needs as standard, from gigabit PoE to 10GbE over Cat6A or fiber, and test every link before the system ships. Send us your cable runs and device list, and we will specify the cabling and ports to match.