Aircraft wiring and the insultation used on the wiring has been a debate since a TWA plane caught fire back in the late 1970's. It was not until a couple years ago that the FAA decided to investigate aircraft wiring. On an aircraft, there are bundles of wires in close proximity. Due to age and vibration, some of the insulation can be removed. The amount of energy available in this location if you have metal to metal conductors touching is incredible. This energy could ignite inflammable material and/or cause all kinds of power surges on equipment. Some tests have shown that the polyimide insulation (Dupont's Kapton) coating over the wire will produce hairline fractures under the normal working environment of an aircraft (vibration, humidity, salty conditions). These fractures subsequently allowed electrical arcing. The problems in the insulation over wire is not limited to Kapton. Poly-X insulation coating is also under scrutiny. To date, Dupont says it knows of no aircraft accident which, on analysis, has been linked to Kapton. It is important to note that this debate is based on the coating on wires. It does not affect Kapton sheet laminates which are used to make flexible heaters, flexible circuits and surface mount style temperature sensors. Also part of this debate centers on the fail safe systems that must be in place to counteract a "runaway situation" (e.g. current limitation controls, fuses etc).
It is not the answer that enlightens, but the question.