Cat 6A or Cat 7: category, class and screening

In network cabling two scales run side by side. The category belongs to the cable and the components, the class to the link you build with them. Cat 5e goes with Class D up to 100 MHz, Cat 6 with Class E up to 250 MHz, Cat 6A with Class EA up to 500 MHz, Cat 7 with Class F up to 600 MHz and Cat 7A with Class FA up to 1,000 MHz. Those frequencies are on our datasheets as well.

Be clear about what those megahertz do and do not tell you. It is the bandwidth the cable is specified over, not the speed you will get. 10 Gigabit over copper calls for Cat 6A across a hundred metres; above that, more MHz buys margin and headroom against interference, not extra gigabits by itself.

You read the screening as xx/xTP. The first part is the screen around the whole cable, the second the one around the pairs. U is no screen, F is foil, S is a braid. So U/UTP is entirely unscreened, F/UTP has foil around the core, U/FTP foil around each individual pair, F/FTP foil around each pair and around the core, and S/FTP a braid around the core and foil around every pair. Foil seals the cable completely and works mainly against high-frequency interference. A braid is mechanically stronger and also works at lower frequencies. Foil around each pair also stops crosstalk between the pairs. We carry all five forms.

Cat 7 deserves a footnote. The category was set out in ISO/IEC 11801 in 2002 as fully screened S/FTP up to 600 MHz, but the American TIA never recognised it. Its connectors are GG45 or TERA rather than the ordinary RJ45. When Cat 6A was ratified in 2008, it became the practical choice for 10 Gigabit; Cat 7 stayed in the picture mainly in Europe, where EMC requirements weigh more heavily. If you choose Cat 7, check first what has to go on either end.

The CPR class depends on the sheath, not the category. Our indoor Cat 5e and Cat 6 are Eca as standard, with Dca or B2ca in a halogen-free version on request. Outdoor Cat 6 has a PE sheath and is Fca. Cat 6A and Cat 7A are Dca-s2,d2,a1 or B2ca-s1a,d1,a1 in LSZH, with Eca for the PVC version. The Cat 7 S/FTP we hold in stock is Dca-s2,d2,a1. The same category in a different sheath is therefore a different class.

For the buyer: name three things at once in the enquiry: the category, the screening and the CPR class. Those three together identify the article. "Cat 6A" alone is not enough, because we supply it in three screening forms and three CPR classes, differing in price and in lead time.