Cat 6 runs up to 250 MHz and gives 1 Gb/s over 100 m, but 10 Gb/s only up to about 55 m. Cat 6A reaches 500 MHz and gives 10 Gb/s over the full 100 m, making it the recommended choice for new installations. Cat 7 reaches 600 MHz, is always shielded and is not recognised by the US TIA standard; with RJ45 connectors it performs no better than Cat 6A.
Category comparison
| Category | Frequency | Speed at 100 m | 10 Gb/s | Shielding |
|---|---|---|---|---|
| Cat 5e | 100 MHz | 1 Gb/s (2.5 Gb/s in many cases) | No | Optional |
| Cat 6 | 250 MHz | 1 Gb/s (2.5 and 5 Gb/s) | Up to about 55 m | Optional |
| Cat 6A | 500 MHz | 10 Gb/s | Yes, 100 m | Optional (U/UTP or shielded) |
| Cat 7 | 600 MHz | 10 Gb/s | Yes, 100 m | Always (S/FTP) |
| Cat 8 | 2000 MHz | 25 or 40 Gb/s up to 30 m | Yes | Always; data-centre use |
The Cat 7 case
Cat 7 is defined in the international ISO/IEC 11801 standard with specific connectors (GG45 or TERA), not the usual RJ45. The US TIA standard does not recognise it. Installed with RJ45 connectors, the whole link is limited to Cat 6A performance, so paying more for Cat 7 cable brings no advantage in a normal network. For a 10 Gb/s-ready network, Cat 6A with all components certified is recommended.
Shielded or unshielded
Shielding only works if the whole chain is shielded and earthed: cable, connectors, patch cords, panels and rack. A shielded cable with ordinary connectors or no earth can behave worse than an unshielded one. Most homes and offices are fine with U/UTP; shielding is justified near motors, drives, switchboards or power runs, in industrial buildings and on long 10 Gb/s runs.
| Type | Meaning | Typical use |
|---|---|---|
| U/UTP | No overall or pair shielding. | Homes and offices without special interference. |
| F/UTP | Aluminium foil around the whole cable. | Cat 6A in offices and moderately noisy environments. |
| U/FTP | Foil on each pair, no overall shield. | Cat 6A with good alien-crosstalk rejection. |
| S/FTP | Overall braid and foil on each pair. | Cat 7 and industrial sites with heavy interference. |
Other details that matter
- Genuine solid copper: avoid CCA (copper-clad aluminium) cable, which does not meet standards and heats up with PoE.
- Outdoor cable with a UV- and moisture-resistant jacket for runs outside the building.
- Halogen-free jacket and a fire-reaction class suited to the building’s use.
- Cat 6A is thicker: allow for conduit and tray sizes and respect the bend radius.
- The whole installation in the same category: cable, connectors, panels and patch cords.
- Certification of every point with a test instrument at the end.