POE Short Circuited

[tcallumg]

Hello,

I have just finished a job where i was swapping the nvr and a few cameras over. Once i swapped over the nvr a camera which was working for a few minutes then turned off and upon investigation it was saying the POE was short circuited. We swapped the camera for a new one and still the same issue. How could we look at combating this?

 

[JB1970]

Hello,

I have just finished a job where i was swapping the nvr and a few cameras over. Once i swapped over the nvr a camera which was working for a few minutes then turned off and upon investigation it was saying the POE was short circuited. We swapped the camera for a new one and still the same issue. How could we look at combating this?

I take it you've already tested the cable with a CAT5 tester? That will immediately show that all pins are connected correctly or if there are any open circuits or shorts.

 

[tcallumg]

I take it you've already tested the cable with a CAT5 tester? That will immediately show that all pins are connected correctly or if there are any open circuits or shorts.

Yeah, tested it on my ideal network tester. Cable tests out fine. It’s very strange.

 

[JB1970]

Yeah, tested it on my ideal network tester. Cable tests out fine. It’s very strange.

Is the camera direct from the PoE port or is the Poe port connected to a switch? I've had NVRs incorrectly show PoE short when connected to a switch.

 

[tcallumg]

Is the camera direct from the PoE port or is the Poe port connected to a switch? I've had NVRs incorrectly show PoE short when connected to a switch.

It’s connected directly into the NVR. It’s strange. It wasn’t originally my install so I’m not sure what’s going on with all of it but I did see that the cable going to the NVR and the one going to the camera are different colours.

 

[JB1970]

It’s connected directly into the NVR. It’s strange. It wasn’t originally my install so I’m not sure what’s going on with all of it but I did see that the cable going to the NVR and the one going to the camera are different colours.

Ah what I meant was - the cable from the PoE port may go to a PoE switch (somewhere) that feeds more than one camera, which sounds possible as you've got different colour cables at each end (if not just a join). If that was the case, some of the ports on the previous NVR would've been configured manually to the addresses of the cameras connected to that switch and as the new NVR would have all ports plug and play as standard, you'd see the non directly connected camera briefly before plug and play kicked in and replaced it's IP address. Just to be sure - do the number of cameras on the site match the number of cables in the PoE ports? If you've got an IP scanner on your laptop, plug the offending cable directly to your laptop, set the laptop IP to 192.168.254.254 and scan - you should get no results. If you do, the camera is being powered from elsewhere and you may get more than one 192.168.254.xxx address in the list.

 

[tcallumg]

Ah what I meant was - the cable from the PoE port may go to a PoE switch (somewhere) that feeds more than one camera, which sounds possible as you've got different colour cables at each end (if not just a join). If that was the case, some of the ports on the previous NVR would've been configured manually to the addresses of the cameras connected to that switch and as the new NVR would have all ports plug and play as standard, you'd see the non directly connected camera briefly before plug and play kicked in and replaced it's IP address. Just to be sure - do the number of cameras on the site match the number of cables in the PoE ports?

Yeah, I checked this. There isn’t one as far as I can see. I also tried plugging the cable into a seperate switch and it never pulled any data. The previous NVR was configured to plug n play on the unit. The number of cameras don’t match but that’s because Today I installed a wireless link to a different building with two extras cameras

 

[JB1970]

Yeah, I checked this. There isn’t one as far as I can see. I also tried plugging the cable into a seperate switch and it never pulled any data. The previous NVR was configured to plug n play on the unit. The number of cameras don’t match but that’s because Today I installed a wireless link to a different building with two extras cameras

Ok. I take it that the short is showing on a channel other than the ones for the wireless link cameras as the PoE injector for the link could cause the NVR to show short (you used to be able to switch off PoE without turning off the channel entirely but that seems to have changed in more recent firmwares). If so, could one of your cameras the other side of the link have a conflicting IP if the channels were left plug and play. I'll usually configure channels connected to a switch (or wireless link) manually, setting the addresses of the cam to channel number plus a hundred so they're out of the way of what the NVR assigns (192.168.254.104 for cam 4 for instance).

If the PoE short disappears when you disconnect that channel. Have you tried connecting to it directly via your laptop and a PoE injector connected to the outgoing cable.

It does seem a strange one....

 

[tcallumg]

Ok. I take it that the short is showing on a channel other than the ones for the wireless link cameras as the PoE injector for the link could cause the NVR to show short (you used to be able to switch off PoE without turning off the channel entirely but that seems to have changed in more recent firmwares). If so, could one of your cameras the other side of the link have a conflicting IP if the channels were left plug and play. I'll usually configure channels connected to a switch (or wireless link) manually, setting the addresses of the cam to channel number plus a hundred so they're out of the way of what the NVR assigns (192.168.254.104 for cam 4 for instance).

If the PoE short disappears when you disconnect that channel. Have you tried connecting to it directly via your laptop and a PoE injector connected to the outgoing cable.

It does seem a strange one....

Yeah,

The Wireless link cameras are connected to the local network with Static IP Addresses instead.

The poe short is gone when i disconnect the cable. I'm beginning to think its an itermitant issue with the cable itself if im being honest as i tested the camera with a patch lead and it worked fine. the only issue is that the cable is under a tarmac driveway.