What is Category 7a?

What is Category 7a?

Category 7a (also written Cat7A) is a twisted-pair cabling specification from the international standard ISO/IEC 11801, where a channel built from Category 7A components is called Class FA. It is rated for frequencies up to 1000 MHz, compared with 600 MHz for Category 7 (Class F) and 500 MHz for Cat6a. It's always fully shielded: each pair has its own foil and the whole cable has an overall braid, a construction called S/FTP.

Connectors

Category 7 and 7a were designed around connectors other than the standard RJ45, such as GG45 (whose jack also accepts RJ45 plugs) and TERA. A standard RJ45 connection can't reach Class FA performance, so cables sold as Cat7 or Cat7a with ordinary RJ45 plugs perform no better than a good Cat6a link in practice.

What it supports

• 10GBASE-T over the full 100-meter channel, the same as Cat6a.
• Very strong resistance to EMI and crosstalk, thanks to the full shielding, as long as the shields are properly grounded.
• No IEEE Ethernet standard requires it. When 25GBASE-T and 40GBASE-T were defined, they were specified for Category 8 cabling, not Cat7a.

Why you rarely see it

The TIA, which publishes the North American TIA-568 cabling standards, never adopted Category 7 or 7a. Cat7a cable is thick and stiff, its shields must be bonded and grounded correctly, and its special connectors limit what equipment it can plug into. Most installers choose Cat6a for 10 Gbps to the desktop and Cat8 for short, very fast data center links.

For the CompTIA A+ exam

Core 1 (220-1201) objective 3.2 covers twisted-pair cable categories in general without singling out Cat7a. Know Cat5e, Cat6, Cat6a and Cat8 well, and treat Cat7 or Cat7a mainly as a distractor: they aren't TIA categories and they weren't designed for standard RJ45 connectors.