2MilesHigh
Here is
an example of what you're querying. It's an accident that happened 34 years ago.
Per the Swissair Flight 111 accident of Sep 98, however, certain types of wiring can dry or wet arc-track and take out whole wiring bundles at a time (obviously causing a multiplicity of unrelated systems failures). Because of the very high temperatures generated by an arc-tracking event, a wire-bundle crossing an oxygen line can cause a pinhole to be burnt into it creating an oxy blow-torch. There has been much surmise that the fan-shaped pattern found in the crown areas of MD-11 HB-IWF was caused by just such an event. The wiring insulation type that can both wet and dry arc-track is the aromatic polyimides (aka/by their generic name of Kapton).
In the SR-111 accident it was found that the L1 and R1 front pax doors had chafing of wiring where the doors recessed into the ceiling. Lengths of wiring associated with the IFEN system were found showing evidence of arc-tracking. After that accident many electrical AD's were introduced. One addressed the vulnerability of the Standby Flight Instruments during bus-failure conditions.
The Final Report of that accident will be released by the TSB in the third week of March. One of the conclusions may be that wiring itself has no "reliable redundancy". In addition, lengthy trouble-shooting checklists for smoke of unknown origin are likely to be found to be a root cause for electrical fires getting out of control (simply because they allow the power to remain on the wiring). The arrangement on the MD-11 for switching manually between busses and generators is called the Smoke/Elec/Air Switch. It kills power to a set of generators and their associated busses - but then reintroduces it as you go on to the next selection. That is like pushing a Circuit Breaker back in on a failed circuit. That is significant because normal CB's will probably not trip during an arc-tracking event. And that is why much effort is being put into developing AFCI's (hybrid CB's called
arc-fault circuit interrupters). But don't expect to see those anytime soon.