Overview
This lecture covers wire mapping (wire map testing) for twisted pair cables, detailing common wiring issues and how to identify them using a cable tester.
What is Wire Mapping?
- Wire mapping tests ensure each wire in a twisted pair cable connects to the correct pin at both ends.
- It identifies wiring problems such as reversed pairs, crossed pairs, split pairs, opens, and shorts.
Common Wiring Problems
- Reversed Pairs: Wires in a pair swap positions from one end to the other.
- Crossed Pairs: Wires from different pairs are crossed between ends (brief mention, not detailed).
- Split Pairs: Wires that should be twisted together are instead twisted with wires from other pairs.
- Open: A wire is broken and does not have electrical continuity from end to end.
- Short: Two wires from different pairs connect at some point, causing current disruption.
Wire Map Testing Process
- UTP cable pin configuration used is EIA/TIA 568A/B.
- Each pin has an assigned color and signal purpose (e.g., orange and green pairs for transmit/receive).
- A cable tester compares the actual wiring with the standard to detect issues.
- Diagrams are used for explanation, but real testing requires a tester, not inspection.
Example Testing Scenarios
- A passing test matches the expected pin configuration exactly.
- Reversed pairs: the same color wires are connected to the wrong pins on one end.
- Split pairs: solid wires from different pairs are swapped, causing signal issues.
- Open: a break in the wire, detected by loss of continuity.
- Short: two wires from different pairs are connected, causing faults.
Key Terms & Definitions
- Wire Mapping — Verifying each wire in a cable is connected to the correct pin on both ends.
- Twisted Pair Cable — Cable type where pairs of wires are twisted together to reduce interference.
- EIA/TIA 568A/B — Standards defining the color coding and pin assignment for network cables.
- Reverse Pair — Both wires in a pair are swapped between ends.
- Split Pair — Wires from different pairs are incorrectly twisted together.
- Open — A wire does not form a complete electrical circuit.
- Short — Two wires are connected where they shouldn't be, causing electrical faults.
Action Items / Next Steps
- Review EIA/TIA 568A/B cable configurations and practice identifying wiring problems using diagrams.
- Use a cable tester to practice recognizing and troubleshooting wire mapping issues.