I have a CCTV camera which is PoE, and an NVR. I already have two cameras connected fine, and have been trying to add a third today.

All the cameras are the same. The cable is Cat5e outdoor.

I've made up two lengths, 1.5m and 18m, the first for testing and the second will be actually used for this camera.

Both cables pass with all 8 lights on the cable tester.

The 1.5m cable works, the camera connects to the NVR.

The 18m cable does not work, the NVR can't see the camera.

I've re-crimped the 18m cable several times, which always passes the cable tester.

With the 18m cable, I know the camera has power, because you can hear a slight 'click' inside when it switches from normal to night vision.

So I can only assume that the 18m cable have signal issues, and not power issues.

Might I have signal issues because the cable is coiled up on the floor, so each part of the cable is right next to lots of other parts of the cable..??

Here's both ends of the 18m cable:

enter image description here enter image description here

  • 3
    No that wouldn't cause trouble. Cat5 cables are routinely bundled together. What is more likely is that you've got the wire pairs in the cable mixed up. This can sometimes still work for very short lengths of cable, but not for longer lengths. Update your question with pictures or diagrams showing the order and colors of the wires as you have them going into the RJ45 connectors on each end so we can confirm if this is the problem.
    – brhans
    Jun 16, 2016 at 12:33
  • I've added two image links... However, the 18m cable passes the cable tester with all 8 lights on both ends... Jun 16, 2016 at 12:55
  • 3
    Most low-cost cable testers only check for simple continuity across the cable and not that the pairs have been used correctly or other possible flaws in the cable.
    – brhans
    Jun 16, 2016 at 13:23
  • 1
    Can't quite make out if white/green & white/blue are correct, but if all else fails, cut the connectors off & try again. Been there, done that - sometimes **it happens without an immediately obvious cause - high speed signalling can be finicky if not done correctly. If that fails get another 18m of cable ... there could be a non-obvious flaw in the length you have. There aren't any nicks or sharp bends in it are there?
    – brhans
    Jun 16, 2016 at 14:50
  • 1
    I wouldn't rule out power issues. What type of camera? Does it have actual 802.3af or 802.3at PoE, or just a simple passive injector and splitter? The difference is 802.3 deals with voltage drop because it runs at 48V and has transformers (and power negotiation circuitry) on both ends, while the passive injectors just put 12V or 5V across a couple pairs. At 18m, if the camera is 1A, you'd get 8.9V or 2V respectively, which may be enough to only partially power the camera up.
    – gregmac
    Jun 16, 2016 at 15:14

1 Answer 1


I routinely test POE network devices with 50m or more of coiled up cable attached to them, particularly when sorting out a new install (it gets to pass the first tests all coiled up before we run it out to the proposed location and test it, then run the final cable through the building.) So coiling is not the issue.

The photos leave it a little vague, but the second one looks like you might have white/green and white/blue mixed up.

  • New cable: amazon.co.uk/dp/B016S76U0C ...works, while coiled up! So you're right about something being wrong with my cable, and it's not a coiled up issue... Jun 18, 2016 at 19:28

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