Every Cat6 keystone jack and RJ45 plug can be wired two ways: T568A or T568B. Use the same standard at both ends of a cable run and the link works perfectly. Mix them up and you have accidentally built a crossover cable. Here is the complete guide to getting terminations right every time.
T568A vs T568B: What Is Actually Different?
Both T568A and T568B are wiring standards defined in the TIA/EIA-568 standard (and referenced in ISO/IEC 11801 as Class D/E/EA specifications). Both use the same four twisted pairs — they simply swap the positions of the green and orange pairs at pins 1, 2, 3, and 6:
- T568B — the de facto commercial standard across the Middle East, United States, and most of the world. The overwhelming majority of commercial cabling in Iraq uses T568B.
- T568A — required by some US government contracts (FCC preference) and more common in older residential installations. Still used in Australia and some European markets.
Recommendation for Iraq: Use T568B everywhere unless an existing site already uses T568A throughout. The only real rule is consistency — same standard at both ends, on every link, properly documented.
Wiring Order: Pin 1 to Pin 8
Looking at the front of the RJ45 plug with the clip facing down and the cable entry at the back (left to right, pins 1–8):
| Pin | T568B Color | T568A Color | Pair |
|---|---|---|---|
| 1 | White-Orange | White-Green | Pair 2 / Pair 3 |
| 2 | Orange | Green | Pair 2 / Pair 3 |
| 3 | White-Green | White-Orange | Pair 3 / Pair 2 |
| 4 | Blue | Blue | Pair 1 |
| 5 | White-Blue | White-Blue | Pair 1 |
| 6 | Green | Orange | Pair 3 / Pair 2 |
| 7 | White-Brown | White-Brown | Pair 4 |
| 8 | Brown | Brown | Pair 4 |
The blue and brown pairs (pins 4/5 and 7/8) are identical in both standards. Only the orange and green pairs swap positions.
Terminating a Cat6 Keystone Jack: Step-by-Step
Follow these steps for a reliable, certifiable termination using DAD LINK Cat.6 UTP or Cat.6A FTP keystone jacks:
Step 1: Strip the Jacket
Remove 3–4 cm (about 1.5") of outer jacket from the cable end. Use a cable stripper, not a knife. Never nick the conductor insulation — even a small nick creates a high-resistance point that fails insertion loss and return loss tests. The stripper's blade depth should be set to just pierce the jacket without reaching the conductors.
Step 2: Preserve the Twists
This is the most critical step. Untwist each pair no more than 13 mm (0.5") from the punch-down point. The twists provide the differential noise cancellation that makes Cat6 work. Every extra millimeter of untwist increases near-end crosstalk (NEXT). Exceeding 13 mm is the single most common reason Cat6 links fail certification testing.
Step 3: Follow the Jack's Color Code
DAD LINK Cat.6 and Cat.6A keystone jacks are printed with both A and B color maps on the jack body. Select the correct side (A or B — whichever you have chosen for the installation) and seat each conductor in the corresponding slot. The colored slot labels make this straightforward — match conductor color to slot color.
Step 4: Punch Down with a 110 Tool
Use a 110-type punch-down tool with the cut side facing outward (away from the jack). Apply firm, consistent pressure to each conductor. A good punch-down makes an audible click. The cut blade trims the excess conductor flush as it terminates. Do not punch down with the cut side facing inward — you will cut the conductor before it seats properly.
Terminate one conductor at a time, not multiple simultaneously. Each conductor needs a solid, individual connection to the IDC (Insulation Displacement Contact) terminal.
Step 5: For Shielded Jacks, Land the Shield
When terminating shielded cables to Cat.6A FTP keystone jacks, fold the foil back over the cable jacket and clamp it against the jack's grounding contact. A floating shield — one that is not properly bonded at both the keystone jack and the patch panel — offers no EMI protection and may even act as an antenna. Ground the cabinet frame at the patch panel end to complete the shielding path.
Step 6: Test the Link
At minimum, test every terminated link with a wiremap tester to verify correct pin connectivity and no shorts or reversals. For commercial and government projects, a channel certification test with a calibrated tester (Fluke DSX, Ideal, or equivalent) verifies that all parameters (insertion loss, NEXT, ELFEXT, return loss, propagation delay) meet the Cat6 or Cat6A standard.
Patch Cords: Why Factory-Terminated Is Better
Hand-crimped RJ45 plugs on stranded Cat6 cable routinely fail Cat6 return loss specifications. The reason: consistent impedance matching at the plug-to-conductor interface requires factory-controlled tooling and matched strain relief components that are not achievable in the field. Factory-terminated, 100% tested DAD LINK Cat.6 and Cat.6A patch cords eliminate the least reliable joint in the channel at very low additional cost.
Common Termination Mistakes and How to Avoid Them
- Using scissors to strip: Scissors compress the jacket and nick conductors. Use a proper cable stripper.
- Excessive untwisting: The most common cause of NEXT failures. Keep untwisted length under 13 mm.
- Mixed standards at each end: The most common cause of "no connection" trouble calls. Document which standard each jack is wired to.
- Not labeling jacks: Every jack should be labeled with its cable identifier within 24 hours of termination, before running more cable obscures which run goes where.
- Floating shields: Shielded cable with ungrounded shields adds noise instead of eliminating it.
- Over-tightening cable ties: A cable tie pulled tight enough to deform the jacket compresses the twisted pairs and increases crosstalk. Ties should be snug, not tight.
Frequently Asked Questions
Can I mix T568A and T568B in one building?
Per link, no — both ends of each cable run must use the same standard. Per building, mixing technically works (each link is straight-through within itself) but creates a documentation and maintenance trap. Standardize on T568B for all new work in Iraq.
Does T568A or T568B affect network speed?
No. Both standards use the same four wire pairs and are electrically identical. Performance is determined entirely by cable category, termination quality, and channel length — not by which wiring standard you choose.
What is a crossover cable?
A crossover cable is wired T568A at one end and T568B at the other. This swaps the transmit and receive pairs, which was historically used to connect two devices of the same type (PC-to-PC, switch-to-switch). Modern equipment with Auto-MDIX handles this automatically, making crossover cables largely obsolete — but structured cabling must still be straight-through.
What tools do I need to terminate a keystone jack?
A cable jacket stripper (not scissors), a 110-type punch-down tool with both cut and no-cut heads, and optionally a flush cutter for trimming conductors. A wiremap tester is essential for verifying every termination before closing the faceplate.
How far can I untwist pairs when terminating Cat6?
No more than 13 mm (0.5 inch) from the punch-down point. This is the TIA-568 specification and is the single most important variable in achieving Cat6 certification performance.
Stock up on DAD LINK keystone jacks and factory-tested patch cords, or contact our team about certification-grade structured cabling installations across Iraq.