THE SHORT ANSWER
T568A and T568B assign the orange and green pairs to different pin positions; the blue and brown pairs stay in place. Follow the scheme specified for the installation and verify both ends. Correct pin continuity still does not prove pair integrity, usable bandwidth or compliance with a cabling category.
Which pins change between T568A and T568B?
The orange and green pairs exchange positions between the two assignments. In T568A, the green pair uses pins 1–2 and the orange pair uses 3–6; in T568B, these are reversed. The blue pair remains on 4–5 and the brown pair on 7–8. Read the numbered diagram before interpreting connector orientation.
Which scheme should you use?
Use the scheme required by the project and existing cable schedule, rather than choosing from a tester’s brand or a cable’s category label. For a straight-through link, maintain the intended pin assignment at both ends. Follow the termination hardware’s labelled instructions, because a jack’s punch-down layout is not the same as a plug’s physical contact order.
- Confirm the project’s required wiring scheme.
- Identify the connector view and numbered pins.
- Follow the hardware manufacturer’s termination labels.
- Verify the completed link and record its outlet and patch-panel identities.
Does using A at one end and B at the other make a split pair?
Using T568A at one end and T568B at the other crosses the orange and green pairs; it does not by itself split their physical pair membership. A split pair is a different error in which a required signal pair uses conductors from different twisted pairs. Equipment tolerating a crossover does not establish compliance with the project specification.
Compare crossed pairs with the split-pair example.
What should you test after termination?
Check the pin map and any required split-pair or shield capability before interpreting the result. A correct wiremap establishes the tested connections, not every transmission parameter. Use qualification for a stated application question, or correctly configured certification for a contractual category or Class requirement, and retain the result with the link identifier.
What else should you check before relying on the result?
A test result is useful only within the instrument’s documented capability and the setup used for that measurement. Check the exact model, permitted connection state and acceptance requirement before acting on a PASS. The questions below clarify common assumptions that can otherwise turn a useful observation into an unsupported conclusion.
Is T568B inherently faster than T568A?
No. These are pin assignments, not speed grades. Cabling performance depends on the cable, components, installation and applicable test method.
Can a continuity pass miss a split pair?
Yes. One-to-one pin connections can use the wrong physical pair membership. Use a tester explicitly capable of detecting split pairs and check its limits.
Which sources support this guide, and what are their limits?
These references support the distinctions and troubleshooting methods described above. Manufacturer capabilities apply to the named model and operating mode; external cases describe the author’s reported observations. Neither is presented as a WireTrace UK measurement. References were checked on 22 September 2026, and project requirements still govern any acceptance test.
- The FOA — illustrated wiremap faults
- Practical Networking (training provider) — Ethernet wiring
- Fluke Networks — cable verification, qualification and certification
What should you record for the next visit?
Record the original symptom, equipment models, cable details, connection state and measurement method alongside the result. After a repair, repeat the conditions that produced the problem and save the retest. The blank field record helps keep expected behaviour separate from observed readings; it contains no example values that could be mistaken for measurements.
Download field record ↓RELATED CAPABILITIES
ContinuityWiremapCertificationRELATED SCENARIOS
100 Mb/s fallbackTester PASS unclear