Structured cabling — standards, categories and fibre optics
ISO/IEC 11801, copper categories and when fiber optics makes sense
Structured cabling is the idea of building a building network according to a fixed, documented plan instead of pulling cables ad hoc as the need arises. The international standard ISO/IEC 11801 describes the requirements for cabling, components and measurement methods, and in Europe, work is often done according to the corresponding EN 50173, which is adapted to the ISO standard.
§Categories and classes
In everyday speech people talk about cable categories like Cat5e Cat6 and Cat6a — this is the North American TIA/EIA designation. ISO/IEC 11801 uses the word 'class' about the entire cabling system and 'category' about the individual components but in practice both are often referred to under the same name.
| Category | ISO class | Bandwidth | Typical use |
|---|---|---|---|
| Cat5e | Class D | 100 MHz | Up to 10 students in a large group |
| Cat6 | Class E | 250 MHz | Up to 112 clock hours |
| Cat6a | Class Ea | 500 MHz | 10 Gbit/s reliable over full 100 metres |
§Copper or fiber?
Copper cabling is cheaper and simpler to terminate but is limited to around 100 meters and is affected by electromagnetic noise. Fiber optics send data as light and is unaffected by electrical noise — it gives much greater range and bandwidth. Multimode fiber is typically used for shorter distances within a building while singlemode fiber with its thinner core is used for the long stretches between buildings or the backbone of a larger network because the signal weakens less over distance.
- 01Patch panels collect the cabling in one place and make recoupling and disconnection clear
- 02Patch cables should have the same or higher category as the fixed installation so as not to become the bottleneck
- 03Power over Ethernet (PoE) sends power through the network cable to for example access points and cameras — the more cables in the same bundle, the more heat the cable must be able to handle
- 04A building's cabling typically has an expected service life of 15–25 years, much longer than the active equipment it serves
§Documentation and lifespan
Because cabling lies hidden in walls and ceilings for years, documentation is crucial. Each cable should be labeled at both ends according to a fixed naming standard, and an updated cabling diagram should show which patch panel field belongs to which room and socket. Without that documentation, even a small troubleshooting ends up costing hours because nobody knows where a cable actually goes.
“Active equipment is replaced every five years. The wiring in the wall should ideally last three times as long — therefore it is what you must not save incorrectly on.”
— Rule of thumb from installation work.