What is a Category Cable and How to Choose the Right One?

Category cable blog post header image

Category cables, commonly referred to as ethernet or Cat cables (“cat” is short for category), are a type of cable used in Ethernet networks. Cat cables are crucial to modern data communication and one of the main ways we connect devices in a local area network (LAN). 

There are many different types of these ethernet cables. All come with special designations. Here we’ll discuss the wires in a Cat cable, why being twisted can be a good thing, clear up some industry jargon, and finally, discuss those categories. 

Or you can go straight to the table to see the differences between the most commonly used Cat cables. 

A Short History of the Cat Cable

A couple of things go hand-in-hand when discussing the history of the ethernet. One is Robert Metcalfe (who cofounded 3Com and created Metcalfe’s Law, among many other things) and David Boggs, who are credited with inventing the ethernet. You can’t have the ethernet without cables, and in 1975, Xerox filed for a patent listing Metcalf, Boggs, Chuck Thacker, and Butler Lampson as inventors of the ethernet cable. 

What Do the Wires in a Category Cable Do? 

If you were to slice a Cat cable in half, you’d see several twisted pairs of copper wire. All are encased in a protective plastic or PVC sheath. For newer iterations of cables, there are eight color-coded wires that are twisted into four pairs. Two pairs are used to receive, and two are used to transmit. Older cables use two pairs, one to transmit data and the other pair to receive data. 

Explain Twisted Pairs and Why This is Important

Ethernet cables contain two insulated wires that are twisted together. The tighter the twisting reduces the electromagnetic field (EMF) disturbances, interference, or crosstalk. By twisting the wires together, the EMF of each wire will cancel each other out and reduce the amount of interference. Cat 6, Cat 6a, Cat 7, and Cat 8 have four twisted pairs. 

What is ANSI, TIA & EIA?

These organizations were crucial in developing and maintaining standards for the telecommunications industry, including the standards and categorization of Cat cables. 

Explain Shielded Vs. Unshielded

The basic definition of shielded and unshielded refers to the type of protective covering of the cable. There are several differences between the two.


  • Shielded cables, designated as STP, Shielded Twisted Pair
  • Individual wires are wrapped in foil, with an extra shielding of foil around all the wires 
  • Secure connection
  • More expensive
  • Shielding helps reduce electromagnetic interference and other disturbances
  • It can be more challenging to install
  • Better protection from environmental elements


  • Unshielded cables designated as UTP, Unshielded Twisted Pair
  • Less secure connection
  • No extra wrapping or protection of wires. Only individual wires are wrapped in foil
  • Do not need grounding

What Do the Numbers Mean on Category Cables?

Cat cables are divided into categories based on bandwidth and other performance features. Some cat cables have become obsolete due to the ever-evolving nature of technology. The number following “Cat” determines the latest version. The letter “a” means augmented, and “e” stands for enhanced. Cat 6a and Cat 6e are not identical. The differences between an “e or “a” designation among any Cat cable could mean a different AWG size rating or other factors. 

NOTE: Cat6e is not recognized in the U.S. Cat7 and C8 are also not approved for use in the U.S. and there is no verifiable way to test it per the EIA/TIA standards. It is important to talk with an expert when making any changes or upgrades to cat cables.

Category Max Bandwidth Max Data Rate # Twisted Pairs Shielding Best Used For Maximum Operating Voltage Maximum Temp to Operate Obsolete
Cat3 16 MHz 10 Mbps 2-4 Unshielded Data Transmission 300V 60 C° Yes
Cat5 100 MHz 1000MBps 2-4 Unshielded Ethernet and voice transmission 300V 60 C° Yes
Cat5e 100 MHz 1000MBps 2-4 Unshielded Gigabit ethernet 300V 60 C° No
Cat6 250MHz 1000MBps 2-4 Shielded or unshielded Internet, Data centers, Telecomm rooms 600V 60 C° No
Cat6a 500MHz 10Gbps 2-4 Shielded or unshielded Internet, Data centers, Telecomm rooms 600V 60 C° No
Cat6e 600MHz 10Gbps 2-4 Shielded or unshielded Internet, Data centers, Telecomm rooms 600V 60 C° No designated connector
Cat7 600MHz 40Gbps 4 Shielded Internet, Data centers, Telecomm rooms 1000V 60 C° Not recognized in U.S.
Cat8 2000 MHz 25Gbps - 40 4 Shielded Data centers, server rooms, high performance computing 200 V 60 C° Not recognized in U.S.

Cat 5 Cable:

This cable has largely been replaced by Cat6 and 7 cables and is considered obsolete and not recognized by TIA/EIA. It has a maximum bandwidth of 100 MHz, a minimum of two twisted pairs, and a maximum of four. 

Cat 5e Cable: 

Cat 5e is still in use and is an “enhanced” version of the Cat 5 cable. It has higher data transfer rates than the 5, and it has improved specifications for crosstalk and interference. This cable is usually unshielded. 

Cat 6 Cable:

Cat 6 cable improves upon the Cat 5e with higher performance and advanced features such as a maximum bandwidth of 250 MHz, reduction of crosstalk and interference, and the ability to be used in different environments. 

Cat 6a Cable:

An “a” was added to distinguish this cable from the original Cat6. It was augmented with improvements, including higher bandwidth and tighter twisting of pairs of wires, further reducing noise. Most Cat 6a cables are shielded, which increases overall performance in high-density and noisy environments. 

Cat 7 Cable:

Cat 7 cables are one of the most advanced categories of ethernet cables, with a maximum bandwidth of 600 MHz This boost in MHz enables high-speed data transfer rates of up to 10 Gbps over 100 meters. Cat 7 cables have four individually shielded pairs of copper wires, which provide superior noise reduction and minimize crosstalk and interference. This cable is ideal for high-density and noisy environments. Many data centers, server rooms, and other areas that need reliable high-speed data transfer are critical to use Cat 7. 

Cat 8 Cable: 

Cat 8 cables are the most advanced ethernet cables. Maximum bandwidth is 2000 MHz which enables data transfer rates of up to 40 Gbps over a distance of up to 30 meters. They have four shielded pairs of copper wires. Like the Cat 7, this cable type is used in data centers and server rooms. In comparison, the Cat 8 is capable of data transfers up to 400 times faster than a Cat 5 cable. Cat 8 and Cat 7 cables are generally not used in the home or small business settings. 

Connect with Confidence at Mars Electric

At Mars Electric, we pride ourselves on providing high-quality electric parts and cables to meet any need. From wiring, tools, equipment, or fasteners and hardware, we have the experts and inventory to help you get the job done. 

If you have questions, we have answers. If you need assistance selecting the right cable, we’re a phone call or a quick drive away. Our knowledgeable customer service team is always here to help. 

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