Coaxial RJ 59 with power

[ians]

I have just experienced the same issue with this type of cable buried in conduits in the ground ... the cable looks ok when you pull it out the conduit ... but once you start stripping th insulation ... its another story ... we talking 2-3 years after installation.

Lesson learnt ... dont bury standard coaxial RJ59 with power in conduits.

I am starting to wonder if we are not going to experience the same issue with cat 5 cable ... I wonder if cat5 or 6 screen would not work better ?

[tec0]

Few factors to consider

1 > heat
2 > power draw
3 > length
4 > exposure.

Typically PoE cables don't last nearly as long as normal CAT5/6

Overheating does degrade the cable along with exposure to heat, moisture and even basic cleaning chemicals.

On average your Cat 5 can last for 10 to 15 years, PoE cables tend to last anything between 3 to 5 years under "normal" conditions.

That said, not all cables and PoE devices are equal some may last a lot longer or deteriorate faster depending on quality and so on.

At 75 ohm it is reasonable to assume that the resistance may contribute to the heat factor.

[ians]

The issue is not a POE cable ... the issue is the pure copper compared to copper tinned cable ... a huge concern in the CCTV industry ... all cat rated cables are not equal.

The test is simple ... when you purchase a cat 5/6 cable ... you simple take out your lighter and burn the wire ... if it melts ... you have the cheap crap cable ... if it glows red ... you have a pure copper.

Its a good idea to google the difference between the two.

One again the customer has no idea why my quote to install the system is more expensive that rats ass technical diversion.

The voltage for standard HDCVI cameras is 12 VDC ... the voltage for POE is much higher (between 44-57 VDC) .. hence the reason you have to be careful when powering up NVR's With built in POE ... the power transformer is normally 48 VDC and the same with POE switches.

[tec0]

comes down to what type of deterioration you are looking at. If the wire goes brittle fast chances are it is getting an unhealthy amount of heat.

Testing resistance can easily tell you what you are dealing with. But i am no expert i just installed CCTV cameras in my early days and found that a lot of problems could have been avoided.

That said my supplier at the time never provided me with bad cables so i guess i was lucky.

[ians]

I dont believe heat is an issue ... in fact I doubt ther eis any heat considering it is buried 500 mm below the surface ... it seems the water which somehow gets into the conduit and sitting in the conduits are the problem ... maybe the ground water causing the problem ... it seems the insulation is breaking down and the causing corrosion inside the cable ... form the outside the cable looks 100 % ok ... only when you test the cable and strip the insulation do you see the problem.

The other concern is the sites are 30 km apart ... both have the same issue ... and the issue is only in the section where the cables are in conduits buried in the ground.