Electrolysis corrosion of ethernet cable when PoE is used.

I laid 2 ethernet cables 15 plus years ago, which is cat5 e. The section that runs under the grass I passed through hosepipe except for a small section where I had to cut a notch into a semicircular pipe so the grill could slip over it. One of the CCTV cameras is a bit flakey, and it was only under investigation that there appears to be some kind of electrolysis happening. There is blue corrosion , my chemistry is a bit rusty but I do know copper sulphate is blue while oxide is black. I'm trying to figure out the mechanism. I'm sure the voltage being applied set up a magnetic field. The metal pipe I am unsure if it is metal. Some reaction must have occured causing heat and plastic to melt in a damp environment causing a short. I am going to have to relay this ethernet cable and the second cable does have a small perforation so that will go the same way. What can I do to protect this second cable?