[wiremonger]

Small tidbit: for cables that are permanently installed in buildings, the insulation and jacket material is more important than the thickness. Typically these installations are inspected by the local jurisdiction and the electrical code is very specific about what gauge conductors have to be used in which circumstances, so the inspection will generally prevent anything egregious enough to cause spontaneous combustion due to heat from electrical resistance.

The bigger issue is that the insulation material will degrade over time if it's consistently exposed to temperatures that are too high, and at that point it becomes a safety hazard because the conductors are no longer properly protected. So typically cables with a higher temperature rating will have insulation and/or an outer jacket made with different materials.