Cabling is laid once and stays for years, so the choice should be based on tomorrow's needs, not just today's. This article compares Cat6, Cat6A and fibre by distance, speed and typical use.
Cabling is the least considered part of an office's infrastructure, yet the hardest to change: once it goes into the walls, suspended ceiling and raised floor, it stays there for years. That is why choosing a cable type means thinking not only about today's computers but also about the access points and devices that will be connected a few years from now. The choice between Cat6, Cat6A and fibre should be made with that in mind.
What does structured cabling mean?
Structured cabling means setting up a standard layout instead of connecting devices straight to the switch with whatever cables are to hand. The socket at each workstation is permanently connected, through the walls and ceiling, to a patch panel in the network cabinet; short patch cables are used between the panel and the switch. This part is called horizontal cabling. Connections between network cabinets, floors or buildings form the backbone cabling.
The benefit of this layout is that changes can be made in the cabinet. When an employee moves desks, there is no need to open the wall; the relevant panel port is simply patched to the right switch port.
The key limit for copper: 100 metres
For the copper network cables used in offices (Cat6, Cat6A), the generally accepted limit is that the total link between the switch and the device must not exceed 100 metres. Of that distance, at most 90 metres is the permanent run inside the walls, with the rest allocated to the patch cables at each end. A meeting room at the end of a long corridor or a large warehouse can exceed this limit when plans are drawn up without measuring. In that case, a second network cabinet is added in between, or the area is reached with fibre.
Cat6, Cat6A and fibre compared
| Feature | Cat6 | Cat6A | Fibre |
|---|---|---|---|
| Frequency bandwidth | 250 MHz | 500 MHz | Transmits with light; this measure doesn't apply |
| Distance at 1 Gbit/s | 100 m | 100 m | From hundreds of metres to kilometres, depending on fibre type |
| Distance at 10 Gbit/s | Up to about 55 m, depending on conditions | 100 m | Multimode OM3 about 300 m, OM4 about 400 m; single-mode many kilometres |
| PoE (power over the cable) | Supported | Supported; its thicker build copes better with heat at high power | Doesn't carry power |
| Installation | Thin, flexible, easy to lay | Thick; needs wider containment and more care | Needs optical modules (SFP), specialist termination and clean connectors |
| Typical use | Desks, printers, phones, cameras | Access points, long-term investment | Backbone, between buildings, long distances |
The distances in the table are general values defined in the standards; real-world performance depends on installation quality and site conditions.
When is Cat6 enough?
For desktop computers, printers, IP phones and most cameras, 1 Gbit/s is more than enough, and Cat6 carries that speed comfortably over 100 metres. Intermediate speeds such as 2.5 and 5 Gbit/s also generally work over Cat6 at 100 metres. In offices with a limited budget, narrow cable containment and no visible need for high speeds at the desk, Cat6 is a sensible choice. The older Cat5e, by contrast, is generally no longer chosen for new installations.
When should you choose Cat6A?
Cat6A can carry 10 Gbit/s up to 100 metres. Because some newer wireless access points come with uplink ports of 2.5 Gbit/s or more, Cat6A is often chosen for the runs to access points in the ceiling. In a building you don't plan to leave for a long time, it also lets you raise speeds later without opening walls.
Cat6A has its costs: the cable is thicker, needs wider containment and has to be bent with more care, and both materials and labour cost more than Cat6. On the other hand, in crowded cable bundles carrying high-power PoE, its thicker build can help heat dissipate better.
When do you need fibre?
Fibre carries data with light instead of electricity. As a result it isn't bound by copper's 100-metre limit and isn't affected by electrical interference. In a small business, fibre is usually run to the backbone rather than to desks:
- When the distance between floors or network cabinets approaches or exceeds 100 metres,
- When two buildings, a warehouse or a production area on the same site need to be connected (copper between buildings carries risk because of earthing differences and lightning; fibre provides electrical isolation),
- When the route passes through an area with heavy electromagnetic interference, such as electric motors or welding machines.
There are two basic types of fibre. Multimode fibre is common inside buildings and on short backbones; OM3 grade carries 10 Gbit/s up to about 300 metres, and OM4 up to about 400 metres. Single-mode fibre is designed for distances of many kilometres and is preferred for long links across a site. Using fibre requires suitable slots on the switches and optical modules (SFP) that match the cable type; termination with the right equipment and keeping connectors clean also matter.
A link performs only as well as its weakest component. When Cat6A cable is combined with Cat6 sockets or low-quality patch cables, the link won't behave like Cat6A. Make sure the cable, sockets, panels and patch cables are of the same category, and from the same system where possible.
What to watch during installation
- Spare sockets and free capacity: Planning at least two sockets per workstation and leaving free space in the containment makes it easier to add runs later.
- Access point and camera runs: Lay the runs for ceiling access points and external cameras from the start; getting cable to these points later is the most laborious job.
- Separation from power cables: Don't lay network cables side by side with power cables in the same trunking; use a separate route or segregated trunking.
- Cable sheath: Inside buildings, low-smoke zero-halogen (LSZH) cables, which give off less smoke and toxic gas in a fire, are widely preferred; the building's fire safety requirements should be followed.
- Shielded cable: Shielded cables help in environments with interference, but don't deliver the expected benefit unless they are earthed correctly end to end. In an ordinary office, unshielded (U/UTP) cable is usually sufficient.
- Labelling: Every socket, panel port and both ends of each cable should carry the same number, and these numbers should be marked on a floor plan.
Testing and handover
A simple cable tester only shows whether the wires are connected in the right order. Whether the link actually meets Cat6 or Cat6A performance is shown by a certification test carried out with a cable analyser. At the end of the installation, ask for these test results for every link, along with the port map and a drawing of the cable routes. These documents also make it easier, if a link causes trouble later, to tell whether the cause is the cable or the device.
Checklist
- Has the number of runs needed for each workstation, access point and camera been determined?
- Has the distance to the furthest point been measured, and does it stay within the 100-metre limit?
- Has Cat6A been considered for access point runs?
- Has the need for fibre between floors or buildings been assessed?
- Are the cable, sockets, panels and patch cables all of the same category?
- Do network cables follow a separate route from power cables?
- Has every link been labelled, and have certification test results been handed over?