The Category Rating System was developed by TIA as a response to the industry's request for higher data rate specifications on applications over unshielded (UTP) and shielded (STP) twisted pair.
This rating systems has been integrated into the body of the EIA/TIA-568A standard document. The category rating system only applies to 100 ohm UTP and STP wiring systems. EIA/TIA-568A also allows 150 ohm STP (also called type I) and 62.5/125 um multi-mode optical fiber.
Category 3 Cable
Category 3 is characterized to 16 MHz and supports applications up to 10 Mbps. Applications may range from voice to 10BaseT.
Category 5 Cable
Category 5 is characterized to 100 Mhz and supports applications up to 100 Mbps. Applications may range from voice to TP-PMD.
Enhanced Category 5
Enhanced Category 5 is still characterized to 100 Mhz and supports applications up to 100 Mbps. However, Enhanced Category 5 provides additional NEXT margin (sometimes referred to as headroom) over the specified frequency band from 1 MHz to 100 MHz. The total noise power with all pairs energized (usually specified as Power Sum NEXT) meets or exceeds the Category 5 specification for worst pair-to-pair NEXT. It also provides improved ELFEXT (Equal Level Far-End Crosstalk) and Return Loss Performance.
Category Safety Requirements
These Safety Requirements are valid for both Category 3 and 5 applications:
- UL 1459 (Telephone)
- UL 1863 (Wire and Jacks)
- NEC 1996, Article 800-4