Ethernet Cable Category Guide

Cat5, Cat5e, Cat6, Cat6A, Cat7, Cat7A, Cat8 — the category numbers all sound similar and the differences matter more than the naming suggests. This lays out speed, distance, and where each one actually belongs, so you're not over- or under-specifying cable for a job.

What to actually run

• Home network — Cat5e is genuinely fine for gigabit at 100m. Cat6 buys headroom for multi-gig later without a full recable.
• New office build — Cat6A should be the floor for new installs. Full 10Gbps to 100m, and it handles PoE++ powered devices without the heat buildup that gives lower categories trouble in dense bundles.
• Server room / data centre — Cat6A for copper up to 10Gbps. Past that, you're looking at DAC cables for short runs or fibre for 25/40/100Gbps — copper just doesn't scale that far.
• PoE cameras and access points — Cat6A or better if you're running high-power PoE++ (up to 90W), specifically to avoid heat building up inside cable bundles carrying multiple powered runs.

Speed isn't the only spec that matters

Higher categories also give you better alien crosstalk rejection — signal bleeding between adjacent cables in the same bundle or conduit — which is invisible on a spec sheet but shows up as intermittent errors and retransmissions that are genuinely painful to diagnose. Throughput can sit noticeably below the theoretical maximum for reasons that have nothing to do with the switch or the NIC, and everything to do with cable quality nobody thought to question because "it's just Cat5e, it works."

When copper stops being the answer

100 metres is the wall for copper Ethernet, full stop, regardless of category. Past that it's fibre — single-mode for kilometre-plus runs, multimode for a few hundred metres at 10Gbps and up. Fibre also doesn't care about electromagnetic interference, which is exactly why it's the default for outdoor runs, building-to-building links, and anywhere near heavy electrical equipment where copper would pick up noise.