Supermunk, you're quite right, the wire that frightened the RAF so much is Kapton. The property of carbon arc tracking was well documented within the services many years ago, although the major airline manufacturers chose to ignore the findings and carried on using the stuff, although belatedly at least Boeing have stopped using it( probably used up all their existing stock).
The exposed wire itself poses no particular worries as if it contacted the airframe the resulting high current would trip the safety devices. The big scare is if a fluid were to be in contact with the bare conductor and either the airframe or another exposed conductor. This sets up a resistive path to earth or between circuits that conducts a current that is within the rating of the fuse or cct breaker. The high current burns the insulation coverting it into carbon, which then continues to burn along the wire, and also burning other wires in the harness or loom.
The absurdity is / was that this undesirable characteristic of Kapton was in use on war planes, which by their very nature are prone to wiring damage.
Yes, we did lose at least two Harriers to suspected fires in the electrical distribution bay in the back end, and they were grounded for several weeks whilst inspection and repairs were carried out.
If treated with kid gloves, tight radii bends avoided and additional protection at potential chafe areas, then it's ok.
It was interesting several months ago on a documentry (can't have been C4 because it was factual and well produced) to witness the denial from the then Boeing spokesman, but there again, the world airliner fleets couldn't be grounded for complete rewires, when the airline industry itself is still regarded to be very safe.
Happy flying .....
