Which statement correctly describes a common cause of a poor Ethernet termination?

• A. The untwisted length of each wire is too long
• B. The woven copper braid should not have been removed
• C. The wrong type of connector is being used
• D. The wires are too thick for the connector

Answer: (A)

In Ethernet terminations, keeping the conductors twisted up to the point they enter the connector is essential for preserving the designed impedance of the pair. When the untwisted length at the termination is too long, that portion no longer maintains the balanced, tightly coupled geometry of the pair. That creates an impedance discontinuity, which can cause reflections and signal integrity problems, leading to a poor termination and data errors. The longer the untwisted portion, the greater the disruption to the characteristic impedance, so this is the most common and impactful cause.

Other factors, like removing shielding, using an incompatible connector, or having wires that are too thick for the connector, can cause their own issues (such as EMI concerns or mechanical/fit problems), but they do not address the core impedance mismatch that comes from excessive untwisted conductor at the termination.