Our cable leaves the plant tested. When a run fails on site, it is nearly always one of these ten. In the order we see them.
1. Untwisting too far at the jack
More than 13 mm of untwisted pair at the termination fails NEXT. Strip less, keep the jacket to within a thumb-width of the jack, punch down and trim.
2. Tight cable ties
A nylon tie pulled hard enough to dent the jacket is a return-loss fault for the life of the cable. Use Velcro, or ties finger-tight.
3. Kinking the cable out of the box
Pulling at an angle from the box, or letting the cable loop and tighten, puts a kink in the pairs that no tester forgives. Pull straight from the box, keep the box upright, and never pull a loop tight.
4. Mixing categories
A CAT6A run with CAT6 patch cords is a CAT6 channel. Use CAT6A patch cords and CAT6A jacks; WIAN patch cords are 24 AWG CAT6A with Wi-Barrier Tape for exactly this reason.
5. Exceeding the bend radius
Eight times the cable diameter — about 50 mm for CAT6A. Sharp 90° turns in a back box or over a tray edge are where it goes wrong. Sweep the bend.
6. Running next to power
Parallel runs alongside mains cable induce noise. Keep 300 mm from unscreened power cables, cross them at right angles, and never share a conduit.
7. Couplers in the run
Every coupler is a return-loss fault and a future failure. If the box ran out, pull a new run; do not join it.
8. Indoor cable outdoors
Even a short stretch across a terrace. Use LDPE-jacketed outdoor cable for the whole run.
9. Not labelling
An unlabelled 48-port panel costs the next technician a day. Label both ends with the run number and the length from the metre marks.
10. Not testing
A link light is not a test. Certify with a Fluke or equivalent, or at least wire-map and length-test every run, and leave the results with the client. It is also the document that protects you when the NVR is blamed for the cable.
Fix these ten and most sites pass first time. The cable will not be the reason they do not.