YES and NO..
Insulation protects more from external heat causing a problem..
Where there is high load currents.... Then you usually get two types of heat related issues..
A: The wiring gets hot and the insulation starts to break down
B: Sometimes the wiring also starts to break down..
Both of these point to the wiring as being under rated or Higher than expected loads ?
A: The crimp / mechanical joins/connectors have a higher resistance and teh current dray develops a localised heat spot.. Usually resulting in brittle joints and vibration and or movement will cause a break..
Guess what.. A picture tells a thousand words and in this situation... If it has not been played with.. The two symptoms are different enough to allow a level of confidence in making a call...
Will wait to see what ya post...