There are right ways and wrong ways to bring power to a fence. The wrong ways often go unnoticed until the voltage drops and the livestock take a trek to the neighbor's garden.
The cause (for this post) is insufficient metal-metal contact. If contact is poor, the pulse is still going to travel through the fence, but with a few added hiccups. Instead of directly traveling from the powerlink to the conductor, it has to 'jump' to make the connection. This jump is called arcing.
The conductor above featured a poor connection so arcing occurred. This caused both the plastic and metal filaments to burn out.
How to avoid poor connections—
If connecting at the end of a roll or net (or junction of two rolls), connect to the metal clip at the end of the net. This will provide the best metal connection (more metal to metal contact).
If connecting at the middle of a net (or length of twine), wrap some MaxiShock around the superconductor (green/white strand on netting) or twine, then connect the clip. The MaxiShock will contact the conductors (in the twine) at more points than simply clipping to the net.
If connecting to 4.5mm (or larger) conductors—wrap a RopeLink around the conductor (below). The rope link will touch the metal filaments at more points and provide a better connection.