Why is the wire twisted in a cat5 cable?

Since 1881 when Alexander Graham Bell patented twisted-pair wires, they are increasingly popular in data communications. But, why is the wire twisted in Cat5 cables specifically?

Twisted cables are one of the more popular forms of wiring used in the application of data communication. These wires provide the actual path over which electrical signals flow from one component to another.

Cat5 cables, among other data communication cables, consist of four pairs of two wires each, twisted together along the length of the entire cable. As a result, you will notice that one twisted pair in the cable has two independently insulated copper wires with thin wires loosely treated around each other. The primary reason as to why the wire is twisted in a Cat5 cable is to reduce electromagnetic interference from other sources in the same cable.

Why is the wire twisted in a cat5 cable?

Electromagnetic interference from within the cable

As discussed earlier, a Cat5 cable has four pairs of twisted wires throughout the entire length of the cable. Each wire produces an unequal amount of electromagnetic force, meaning one wire can interfere with the function of the other. Given that Gigabit Ethernet has eight conductors that it uses simultaneously, all conductors would not perform optimally if they all generated their electromagnetic field at the same time. It is this passing of electrons back and forth between conductors that is referred to as crosstalk interference.

Despite Ethernet cables having low voltage, its small magnetic field still affects its performance. As a result, the use of the twist is to reduce such interference and protect the cable from itself. At each and every twist on the conductors, it reduces the polarity by canceling out the difference in their individual electromagnetic fields. Therefore, the twist allows the cable to achieve an electromagnetic balance, allowing the wires to work in harmony with each other.

Twist ratio within a Cat5 cable

You might also notice that each pair within the cable has a varying degree of twists, also known as twist ratio. As a general rule of thumb, the higher the twist ratio, the more reduced crosstalk of wires within the cable. As a result, a cable with more twists offers greater signal integrity.

More so, cables with tighter twists allow any electromagnetic interference to affect both wires equally, resulting in no change in the difference between them. Therefore, you can transfer data over much longer distances. Tighter twists also reduce more cable noise as one wire’s magnetic field cancels out the others. It is also crucial to note that Cat5e cables feature a changing twist ratio compared to Cat5 cables, meaning they can handle a larger workload than their predecessor.

Electromagnetic interference from outside the cable

Whether shielded or unshielded, all Ethernet cables come with their own in-built shielding in the form of twisted pairs. The only difference is that shielded twisted Cat5 cables have an additional exterior foil shield that protects the cable from radio waves or magnetic fields from outside your cable from getting inside your cable.

Therefore, unshielded twisted cables reduce electromagnetic noise and crosstalk. Alternatively, shielded twisted cables can possibly significantly or eradicate electromagnetic interference, noise, and crosstalk. These shielded cables come with a braided or metal foil mesh that enclose the twisted pair wires, protecting the wires from outside electromagnetic interference. As a result, they can carry data at an increased rate compared to unshielded twisted cables.

Why are the twisted pair wires in a Cat5 cable of different colors?

Cat5 cables come in a combination of twisted wires, all of different colors. There are those with white/blue stripe, white/orange stripe, white/green stripe, and white/brown stripe. The different colors of the insulation are for identification purposes. As a result, when you say the third pair of wires, it means the green pair.

The different colors also identify the specific conductors  in each cable and how they relate to other pairs in the cable. For more information on these colors and what they stand for, the Telecommunications Industry Association(TIA) provided a wiring color breakdown as of 2018.

Conclusion

The twisted pair wires in a Cat5 cable serve as a transmission medium. Despite having different manufacture and design, they offer reliable connectivity of various electronic equipment. As a result, it is vital to invest in a high-quality cable to receive its full benefit.

Frequently Asked Questions

Is the color order of Cat5 wires important?

The color order of a standard Cat5 cable does not matter as long as they are in the same order on both ends.

Does a Cat5 cable use all of its four pairs of wires?

Fast Ethernet communications, like those under 10Base T and 100 Base T standards, use only two of these pairs for transmitting and receiving data. Cat5 cables that support 1000Mbps (short-run Gigabit Ethernet networking) use all four pairs.