Category 5 cabling is a level 5 grade of unshielded twisted-pair (UTP) cabling.
What is Category 5 cabling?
Category 5 cabling was designed to support digital voice and data communication at speeds up to 100 Mbps. It uses 22-gauge or 24-gauge copper wires in a configuration of four twisted-pairs enclosed in a protective insulating sheath. Before Category 6 was released, Cat5E Cable was the most used type of cabling on computer networks.
CAT5 cabling is the standard grade of UTP cabling for networks such as:
Category 5 cabling is always recommended for new installations of premise cabling and for upgrading existing premise wiring for higher-speed networks, because of its superior electrical characteristics. It is the highest grade of UTP cabling currently recognized by the Electronic Industries Alliance (EIA) and Telecommunications Industry Association (TIA), although proposals there have been made for higher category 6 and category 7 grades.
See: difference between CAT5 and CAT6 cabling.
Many vendors offer an enhanced category 5 cabling grade with electrical characteristics exceeding those of standard CAT5. Enhanced CAT5 cabling supports data transmission up to frequencies of 350 MHz, and new standards are under development to allow even higher data transmission frequencies.
Category 5 Cabling Characteristics
The following table summarizes the electrical characteristics of CAT5 cabling at different frequencies, which correspond to different data transmission speeds. Note that attenuation increases with frequency, while near-end crosstalk (NEXT) decreases.
| Characteristic | Value at 10 MHz | Value at 100 MHz |
| Attenuation | 20 decibels/1000 feet | 67 decibels/1000 feet |
| NEXT | 47 decibels/1000 feet | 32 decibels/1000 feet |
| Resistance | 28.6 ohms/1000 feet | 28.6 ohms/1000 feet |
| Impedance | 100 ohms (± 15%) | 100 ohms (± 15%) |
| Capacitance | 18 pF/ft. | 18 pF/ft. |
CAT5
Category 5 cabling is usually referred to simply as “CAT5.” UTP cables using CAT5 should be no more than 90 meters in length for typical Ethernet and Fast Ethernet installations, and patch cords should be no longer than 10 meters.