Cat6 or Cat6A? Choosing the right cabling for your office

'Cat6 or Cat6A?' is the first question in almost every new office fit-out or refurbishment. Cabling stays in the walls and ceilings for 15 to 20 years, while switches, access points and computers are replaced several times over that period. So the choice is not only about today, but about the equipment you will plug in five or ten years from now.

Below we explain in plain terms what changes between the two categories: speeds and distances, PoE and heat, shielding, what affects the cost, and when the right answer is neither, but fibre. At the end you will find our recommendations for typical offices.

Cat6 or Cat6A: the key differences at a glance

• Bandwidth: Cat6 is specified up to 250 MHz, Cat6A up to 500 MHz. More bandwidth means headroom for higher speeds.
• 1 Gbps: both support it over the full 100 metres.
• 10 Gbps: Cat6A over the full 100 metres. Cat6 only over shorter runs, typically up to 37–55 metres, depending on installation conditions and crosstalk from neighbouring cables.
• 2.5 and 5 Gbps (NBASE-T): both normally support these up to 100 metres, which matters for modern access points.
• Diameter and weight: Cat6A is thicker and stiffer, takes up more space in conduits, trunking and trays, and needs a larger bend radius.
• Installation: terminating Cat6A is more demanding and takes longer per point.

The 100-metre limit applies to both categories and covers the whole channel: up to 90 metres of permanent cabling from the patch panel to the wall outlet, plus about 10 metres in total for the patch cords at both ends.

Speeds and distances in practice

In a typical office, computers need 1 Gbps, and that is not going to change soon for the average desk. There, Cat6 is more than enough. The picture changes at the points where traffic concentrates.

• Wi-Fi 6, 6E and 7 access points: most business models have a 2.5 Gbps port, and higher-end ones 5 or 10 Gbps. A busy Wi-Fi 7 access point can genuinely exceed 1 Gbps.
• Servers, NAS units and workstations for video, CAD or photography: here 10 Gbps makes a visible difference when moving large files.
• Links between switches (uplinks): if they are not on fibre, they must carry the combined traffic of every device below them.

If a Cat6 run is 25 metres, it will probably work at 10 Gbps. If it is 70 metres, not reliably. On large floors, where many runs exceed 50 metres, Cat6A is the only way to get guaranteed 10 Gbps over copper.

PoE and heat: why the category matters

PoE (Power over Ethernet) carries power from the switch to the device over the same cable. It powers access points, IP cameras, VoIP phones, access-control readers and many IoT devices without a socket next to them.

• IEEE 802.3af (PoE): up to 15.4 W per port.
• IEEE 802.3at (PoE+): up to 30 W per port.
• IEEE 802.3bt (PoE++): up to 60 W (Type 3) or 90 W (Type 4) per port, for powerful access points, PTZ cameras, displays and lighting.

Current flowing through the conductors warms the cable. A single cable is fine. But when dozens of PoE cables run together in a bundle, in closed trunking or in an insulated ceiling void, the temperature at the centre of the bundle rises. Higher temperature increases signal loss and, in extreme cases, shortens the life of the cable.

Cat6A cables usually have thicker conductors (23 AWG) and dissipate heat better. That is why they cope better with large bundles carrying high-power PoE. Whatever the category:

• Use solid copper conductors. Cheap CCA cable (copper-clad aluminium) is not suitable for PoE and is not genuine Cat6.
• Do not tighten large bundles: split cables into smaller groups and leave air between them.
• Keep PoE bundles away from heat sources such as warm-air ducts or light fittings.

If you are planning many access points or PoE++ cameras, tell your installer from the start. Routes and bundle sizes are designed differently when we know the cables will carry power.

Shielded or unshielded (UTP, FTP, S/FTP)?

Both Cat6 and Cat6A come in unshielded (U/UTP) and shielded versions (F/UTP, U/FTP, S/FTP). The shield is an aluminium foil or braid around the pairs that protects against electromagnetic interference.

• In most offices, unshielded U/UTP is enough, cheaper and easier to install.
• We prefer shielded cable near industrial machinery, motors, inverters, lifts, medical equipment, or where data cables must run close to power cables.
• Shielding only works if it is continuous end to end: shielded keystones, a shielded patch panel and proper earthing of the rack. Shielded cable with unshielded components is money spent for no benefit.

One point that is often forgotten: every component in a channel must be the same category. Cat6A cable with Cat6 outlets or patch panels performs as Cat6. The channel is only as good as its weakest part.

What drives the cost

Cat6A costs more than Cat6, but the difference in the finished job is rarely just the price of cable per metre. These are the factors that push the cost of an installation up or down:

• The cable itself: Cat6A costs more per metre, and shielded even more.
• Components: Cat6A keystones, outlets, patch panels and patch cords cost more.
• Containment: because of its diameter, Cat6A may need larger trunking, conduits or trays.
• Labour: terminating Cat6A takes longer, and shielded cable longer still.
• Certification: testing each run with a cable certifier is good practice for both categories, but with Cat6A it is effectively the only way to know it meets the specification.
• The building itself: ceiling voids, plasterboard and existing conduits make the work simpler, while concrete, older buildings and occupied premises make it more demanding.

In a new installation, much of the cost is labour and routing, which are almost the same for both categories. That is why the gap between a Cat6 and a Cat6A project is usually smaller than cable prices suggest. Replacing cabling later, on the other hand, means more labour, more making good and more downtime.

When you need neither, but fibre

Copper has a hard limit of 100 metres. Fibre does not have that problem and is immune to electromagnetic interference. We recommend fibre when:

• You are linking floors or racks more than 90 metres apart by cable route.
• You are linking two buildings, e.g. offices and a warehouse. Beyond distance, fibre does not conduct electricity, so it protects against earth potential differences and lightning surges.
• You need a backbone of 10 Gbps or more between switches.
• The cable passes through an industrial area with heavy electrical noise.

Inside buildings, multimode OM3 or OM4 fibre is the usual choice. For long distances and future flexibility, single-mode OS2. The right type depends on distances and the transceivers you will use. For desks, access points and cameras, copper remains the practical answer, because it also carries PoE.

Our recommendations for offices

There is no single answer for everyone, but most of our projects end up in one of these scenarios:

1. Small office up to 15 desks, short runs: Cat6 U/UTP to all desks, Cat6A to access point locations and to the server or NAS position.
2. New office or full refurbishment that will stay for many years: Cat6A throughout. The extra investment is small compared with the lifetime of the cabling.
3. Large floor with runs over 50 metres or many PoE devices: Cat6A, with properly designed bundles.
4. Multi-storey or multi-building site: fibre between racks, Cat6 or Cat6A from each rack to the desks.
5. Areas with machinery or heavy interference: shielded Cat6A with proper earthing, or fibre where possible.

If the office is leased for a few years and the budget is tight, a properly installed solid-copper Cat6 system is a far better choice than a sloppy Cat6A one. Installation quality matters as much as the category.

Always ask for test results for every run and labels at both ends. Without test results, 'Cat6A' on a quote is just a word.

Quick answers to common questions

• Is Cat7 or Cat8 worth it? For offices, no. Cat7 is not a TIA standard and specifies different connectors, while Cat8 is designed for very short runs inside data centres.
• Does existing Cat5e need replacing? Not necessarily. If it is properly installed, it delivers 1 Gbps and often 2.5 Gbps. It is worth testing before you decide.
• Can I have Cat6 and Cat6A in the same office? Yes, on different runs. Within a single run, however, all components must be the same category.

How we help

CyberSpace Dynamics designs and installs Cat6 and Cat6A structured cabling in offices, shops and warehouses across Attica. We survey the site, recommend the right category for each point, terminate on patch panels and racks, label everything and hand over documentation.

If you are not sure whether Cat6 or Cat6A suits you, send us a floor plan or photos of the space for an estimate, or book a free site survey. We will explain what fits your premises and why.