Twisted pair: Why Twist the Wires

Many IT professionals or cabling experts are often asked: “Why are the wires twisted inside the Ethernet Cables?” Here we will discuss the answer to this question by delving into the inner workings of the Ethernet cable.

 Inside the Ethernet Cable

Ethernet cable is constructed with four twisted pairs of insulated wires braided together and encased in a sturdy jacket.  Eight conductors create four twisted pairs. These twisted pairs are vitally important for the function of the cable. Let’s find out why.

Why Twist the Wires?

The twisted design provides a “built-in” shielding for each Ethernet wire within the cable. The twist ensures the wires are balanced and close together as they alternate down the length of the cable.

 This twisting helps maintain the same position throughout the cable which reduces internal electromagnetic interference and prevents crosstalk, slow data transfer speeds and obstruction of signal transmission.

In other words, the cable will not function as well without the “built-in” shielding in the form of twisted pairs because each wire conductor generates an unequal electromagnetic-field and can interfere with one another. 

With each twist, it creates a reverse in polarity of the conductors which then cancels out the differences in their individual electromagnetic fields. This is why Ethernet cables are also known as balanced twisted pair.

Twist Rates

The twist rate is typically measured as number of twists per inch or centimeter. For example, Cat5e cables typically have a rate of 4-5 twists per inch and Cat6 cables typically have a rate of 5 or more twists per inch.  In addition, not all 4 twisted pairs in a cable have the same twist rate. Variation in the twist rate ensures that twists will not lined up and will reduce the crosstalk between pairs. In the IEEE or TIA category cable standards, twist rate is not specified, therefore, it is up to the manufacturer to decide the rate.

Color Scheme of Twisted Wires

The twisted pairs are typically blue, orange, brown and green. The wires typically follow a similar arrangement, with one being a solid color or mostly solid, and the other white with a colored stripe. 

Here is an example:

• Solid Blue – White/Blue stripe
• Solid Orange – White/Orange stripe
• Solid Brown – White/Brown stripe
• Solid Green – White/Green stripe

The colors are used to help people to differentiate the different pairs and know they are using the same scheme on both ends of the cable. Read more about RJ45 Color Codes

Interesting fact

In the early years of telephone lines, they were found to be affected by interference from electrical wires that shared the same telephone pole. Engineers came to discover that by alternating the telephone wires every few poles (ie: left line became right and right line became left), they could ultimately reduce the distortion. This technique was the first use of twisting wires discovered by Alexander Graham Bell.

 We hope this quick guide to “Why wires are twisted in Ethernet Cables” has helped you get a better understand on the subject. If you are looking to purchase Ethernet Cables, SatMaximum offers bulk network cables in a wide variety for all your home or business needs.