Question:
Why does LinkIQ report a different length for each wire pair?
Answer:
Your LinkIQ reports an OPEN or SHORT and you wonder how accurate the information is because it shows slightly different lengths for the other pairs.
- Example Test Result
- Explanation
- Suggestion
Example Test Result
Link IQ reports an OPEN for pin 5
and you tap to get more detail and learn where in the cable the OPEN was detected.
You see that the defect is located 8.6 meters into the cable. You also observe that the tester reports a slightly different length for the other pairs. In this example 15.2, 14.9 and 14.8 meter.
The different cable pairs in twisted pair cable have a different length by design
Using wire pairs with a different twist rate is a design found in virtual all twisted pair cable design because it is a very effective method to reduce the crosstalk between the pairs. This different twist rate results in the observed difference in "electrical length".
Do not make knowing the exact location of the defect part of your repair strategy
Since we do not cut open the jacket of the cable to repair the inside it should be sufficient to know the distance with a small error. We still will be able to locate the bad connection or the sharp metal part which pinched the cable.