The Difference in the Twists at Each End of a 4 Twisted Pair Cable and Why They Matter

The Difference in the Twists at Each End of a 4 Twisted Pair Cable and Why They Matter

A 4 twisted pair cable, such as Cat5e or Cat6, is designed with eight individual copper wires twisted into four pairs. Each pair is color-coded: Blue, Orange, Green, and Brown, with each pair consisting of a solid-colored wire and a striped wire. One important detail that often goes unnoticed is that the order of the color codes seems to “change” at each end of the cable, and this is due to how the twisted pairs are manufactured and terminated.

Why Are the Pairs Twisted Differently?

Each pair in a twisted pair cable is twisted at a different rate (twists per inch) to reduce electromagnetic interference (EMI) and crosstalk. This difference in twist rates prevents signal degradation, especially over long distances.

Orange Pair: Typically has the highest twist rate.

Green Pair: Slightly fewer twists than the orange pair.

Blue Pair: Moderate twist rate.

Brown Pair: Lowest twist rate among the four pairs.

This variation ensures that no two pairs have the same twist length, minimizing the chances of interference between them.

The “Change” in Color Order at Each End

When terminating a cable, whether using the T568A or T568B wiring standard, you may notice that the color code order appears different at each end. This is not a mistake but rather a result of the twisting inside the cable.

At one end, the pairs might appear in a certain order when untwisted, but at the other end, the pairs seem to shift. This occurs because:

1. Twisting Lengths: Each pair has a different twist length, so when you strip the cable jacket at one end, the pairs may present themselves in a different sequence compared to the other end.

2. Maintaining Signal Integrity: The varied twist rates ensure that signals remain balanced and reduce the risk of interference, even though the physical appearance of the pairs might differ at each end.

3. Color Code Standards: The T568A and T568B standards ensure that despite the differences in twist lengths, each wire is correctly aligned for proper signal transmission.

 

Why Is This Important?

The differences in twist rates and how they appear at each end of the cable are crucial for:

Signal Quality: Maintaining the twists as close as possible to the termination point ensures minimal signal loss.

Proper Functioning: Even though the order may look different, following the wiring standards ensures that the correct pairs are connected.

Network Performance: Poorly maintained twists can result in crosstalk, slower data speeds, and connection issues.

In short, the difference in twists at each end of a 4 twisted pair cable is by design, ensuring that the cable performs efficiently while maintaining proper signal integrity across the entire network.

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Source: LinkedIn

Credits: Mr. Ramtin Tourchian