Which structured cabling is right for you? CAT6 or CAT6A.

A short guide from Pensdown, the electrical people

When you are planning the digital infrastructure of your building, one decision matters more than most - what cabling should you install. It’s not glamorous, but it’s critical. Choosing between CAT6 and CAT6A cables can determine how fast your network runs, how reliable your systems are and how much you'll have to rip out and replace in a few years. In a business landscape driven by data, speed and connectivity, the wrong choice could mean a costly step backwards. Here's what you need to know - clearly, factually, and without the jargon.

It might sound like a technical detail best left to your IT contractor, but it’s a choice that affects your entire digital infrastructure - from performance and cost to energy usage and futureproofing. Get it wrong, and you might face slowdowns, upgrade costs, or limits to adopting next-generation technologies.

What is structured cabling?

Structured cabling is the organised system of cables, connectors, pathways and hardware that forms the backbone of your network. It includes everything from the cables in your walls to the patch panels in your server rooms. Think of it as the road network that all your data travels on.

It’s "structured" because it follows specific standards, making it easier to manage, upgrade and troubleshoot compared to ad-hoc or "spaghetti" cabling.

Structured cabling connects:

• Computers and phones

• Wireless access points

• Security cameras

• Building management systems

• Audio-visual equipment

• And much more

At the centre of all this are the Ethernet cables, commonly known by categories like CAT5e, CAT6, CAT6A, CAT7, and CAT8. Among these, CAT6 and CAT6A are the most widely used in new commercial installations today.

What’s the difference between CAT6 and CAT6A?

CAT6 and CAT6A are both types of twisted pair Ethernet cables used for high-speed data transmission. While they might look similar on the outside, there are key differences:

• Speed and bandwidth

• Maximum cable length

• Shielding and crosstalk

• Physical size and flexibility

• Cost

• Future-readiness

Let’s look at each in turn.

Speed and bandwidth

• CAT6 supports speeds up to 1 Gbps (Gigabit per second) over distances of up to 100 metres. It can also support 10 Gbps, but only over short distances - up to around 37-55 metres, depending on conditions.

• CAT6A is designed for full 10 Gbps transmission over the full 100 metre distance. It also supports 500 MHz of bandwidth, double that of CAT6 (250 MHz).

What does this mean? If you're planning for 10-Gigabit networking - especially over larger areas or across multiple floors – then CAT6A is the safer choice.

Cable length and performance

Both CAT6 and CAT6A are rated for up to 100 metres total distance (90 metres of solid cable plus 10 metres of patch leads). But there's a catch:

• With CAT6, performance at 10 Gbps begins to degrade beyond 37–55 metres.

• CAT6A, on the other hand, delivers reliable 10 Gbps up to the full 100 metres.

This matters in larger offices, hospitals, schools, data centres or any environment where equipment rooms are not always close to users.

Both cable types are backward-compatible with lower-speed networks (e.g. 1 Gbps, 100 Mbps), so you can mix them safely in upgrades.

Crosstalk and shielding

“Crosstalk” is electrical interference from adjacent cables, which can degrade signal quality.

• CAT6 uses tighter twists in the copper pairs to reduce crosstalk compared to CAT5e, but it's still vulnerable, especially at higher speeds.

• CAT6A is available as U/UTP (unshielded), F/UTP (foil shield), or S/FTP (individually shielded pairs). Even unshielded CAT6A performs better against alien crosstalk than CAT6 due to its internal separators and tighter twists.

Bottom line: CAT6A is better at protecting signal integrity in high-density cable environments - like server rooms or busy office risers.

Cable Size and Flexibility

• CAT6 is thinner and more flexible, making it easier to install in tight spaces.

• CAT6A is thicker and heavier, with larger bend radii due to shielding and extra insulation.

• CAT6A cables are typically 7–8 mm in diameter compared to 5.5–6 mm for CAT6.”

This can affect:

• Cable trays and conduit size by around 30%

• Termination points

• Ease of installation

• Cooling and airflow in dense IT environments

Some installers resist CAT6A because of the extra effort and space required, especially in retrofit jobs.

Cost

CAT6A costs more than CAT6.

• Material cost: Around 30–50% higher for cable and connectors.

• Labour cost: Higher due to thicker cables, larger pathways and more careful handling.

• Hardware: Patch panels, jacks and tools for CAT6A tend to cost more.

However, the cost of cabling is a small fraction of your total IT spend and cabling is the one part you’re unlikely to replace for 15 - 20 years. Spending a bit more now could save you a costly replacement job later.

Futureproofing and emerging tech

Today, many devices still use 1 Gbps networking. But that’s changing - fast.

• Video conferencing, 4K/8K video, cloud applications and file sharing demand higher speeds.

• Wi-Fi 6 and 6E (and the upcoming Wi-Fi 7) access points often need 2.5, 5 or 10 Gbps uplinks.

• IoT and smart building tech rely on fast, stable cabling infrastructure.

• Power over Ethernet (PoE) for phones, cameras and access control also performs better with higher-spec cables.

• CAT6A’s thicker conductors reduce resistance and heat build-up, making it more suitable for high-power PoE++ (up to 90 W) applications.

CAT6A is better suited to support these demands, while CAT6 may reach its limits sooner than you think.

When to Choose CAT6 or CAT6A

Making the right decision:

Choose CAT6 if...

• You’re building a small office or branch site with basic networking needs.

• Your infrastructure will not require 10 Gbps any time soon.

• Your cabling runs are under 55 metres.

• Budget is tight and you're optimising for short-term value.

Choose CAT6A if...

• You're futureproofing a new building for 10 Gbps or higher.

• You have long cable runs or large premises.

• You're deploying high-speed Wi-Fi, IP security, or dense IoT systems.

• You’re building a hospital, data centre, school, university, or warehouse.

• You want your infrastructure to last 15 - 20 years without upgrades.

What About Other Categories? CAT5e? CAT7? CAT8?

• CAT5e is outdated. Still common, but not recommended for new installs. Limited to 1 Gbps.

• CAT7 and CAT8 are primarily for data centre use. They offer higher speeds but use non-standard connectors (like GG45 or TERA) and are overkill (and costly) for most commercial applications.

For most office, education, and enterprise environments, CAT6 and CAT6A remain the two most relevant and practical choices.

A Word on Installation

Choosing the right cable is only part of the story. Installation quality matters.

• Poor terminations can undermine performance.

• Bending cables too tightly can damage shielding or insulation.

• Mixing components (e.g., CAT6 cable with CAT5e jacks) creates a weak link.

• Cable bundles must be properly spaced and cooled in high-density environments.

That’s why you should always work with a certified cabling contractor who provides certification to TIA 568-D or ISO/IEC 11801 standards, with test results showing compliance up to 500 MHz for CAT6A.

6 or 6A at a glance

Fire Safety and CPR Cable Ratings

When selecting data cabling for a commercial installation, it’s important to ensure compliance with the Construction Products Regulation (CPR), which sets fire safety standards for cables used in buildings. CPR ratings are expressed as Euroclass designations — such as Eca, Dca, or Cca — indicating a cable’s performance in fire conditions.

• Eca: Basic flame retardance suitable for low-risk areas.

• Dca: Offers improved flame spread and heat release performance, typically required in offices, schools, and public buildings.

• Cca: Higher fire resistance and lower smoke emission — often specified for escape routes, high-occupancy, or critical environments.

All structured cabling installed in the UK should be CPR-certified and CE/UKCA marked, with the Euroclass clearly stated on the cable sheath and documentation. Choosing an appropriate CPR rating helps ensure compliance with BS EN 50575 and contributes to overall building fire safety.

Final thoughts

Structured cabling is not exciting, but it is essential. Like the plumbing in a high-rise building or the concrete in a bridge, you only notice it when something goes wrong.

Choosing between CAT6 and CAT6A is not just a technical choice - it’s a strategic business decision. It can shape how your network performs, how fast your team works, how ready you are for the next generation of devices and how much you will need to spend in five years to stay competitive.

Even if your switches and devices don’t currently run at 10 Gbps, CAT6A ensures your cabling won’t limit you when you upgrade to faster Wi-Fi or multi-gigabit switches.

In most cases, CAT6A is the smarter long-term investment, especially for new builds or major refurbishments. Yes, it costs more up front, but it provides the speed, stability and scalability modern businesses demand.

Still unsure? Speak to your IT team, facilities manager or a certified network designer. Make the