Network Cabling Categories: Cat5e, Cat6, Cat6a and What to Install

Cabling is the part of an installation that outlasts everything plugged into it, and the part most likely to limit what you can install later. This covers what each category actually carries and when it matters.

What the categories mean

Each category is a specification for how much bandwidth the cable can carry reliably over a given distance.

Cat5e — gigabit over normal runs. Still everywhere, still adequate for gigabit, and increasingly the thing that stops an upgrade.

Cat6 — gigabit comfortably, and 10 gigabit over shorter runs. The distance limit for 10GbE on Cat6 is the detail people miss.

Cat6a — 10 gigabit over full-length runs. This is the practical choice for new installations where 10GbE might be needed.

Cat7 and Cat8 exist for higher speeds and shorter distances, and are specialised rather than general-purpose.

The rule that matters: a link runs at the speed the whole path supports — cable, patch panels, patch leads and wall outlets. One Cat5e patch lead in a Cat6a run limits the whole link.

Why this decides upgrades later

Cabling is installed once and stays for a decade or more. Equipment changes several times in that period.

So the question when installing is not what you need now but what you might need before the cabling is next replaced. The cost difference between categories at installation is small; the cost of recabling a building later is not.

This matters most where 10GbE is plausible: storage networks, virtualisation hosts, and increasingly access points. Our iSCSI guide covers why storage traffic needs the bandwidth.

Copper or fibre?

Copper for runs within a building, up to the distance limit. Cheaper, simpler, and it can carry power over Ethernet.

Fibre for longer runs, between buildings, in electrically noisy environments, and where you want the link to be immune to interference. It carries no power, so a fibre-connected device needs its own.

The distance limit on copper is the usual deciding factor. Beyond it, fibre is not a preference but a requirement. Our fibre guide covers handling it, and our transceiver guide covers the modules each end needs.

Power over Ethernet: what the cable must support

PoE delivers power down the same cable as data, and higher PoE standards deliver considerably more.

Two things follow. Higher power generates heat in the cable bundle, and tightly packed bundles of cables all delivering power run warmer than the specification assumes. And cable quality matters more — poor conductors waste power as heat over the run.

Where you are deploying many PoE devices, the cabling specification and the bundling both deserve attention rather than being assumed. Our switch guide covers the PoE budget side.

Patch leads: the weak link

Structured cabling is installed carefully and tested. Patch leads are bought cheaply and replaced casually, and they are where most cabling faults actually are.

Three points.

Match the category across every part of the path, including the patch leads at both ends.

Length matters. The total path includes patch leads, so long leads at each end eat into the run budget.

Damaged leads fail intermittently, which is far harder to diagnose than a clean break. A link that works but shows errors is frequently a patch lead.

Labelling and documentation

The thing that makes cabling maintainable.

Both ends of every cable, with a scheme that identifies the other end.

Patch panel ports mapped to outlet locations, kept current.

A record of what runs where, stored somewhere that survives the network being down.

This is tedious and it is the difference between a ten-minute fault and a two-hour one. Our network documentation guide covers doing it, and our labelling guide covers the scheme.

Frequently asked questions

Tell us the speeds you need now and might need in five years, and we will tell you what the cabling has to be today.