Wire "melting" usually refers to the melting and burning of insulation. The copper core melts only under extreme faults with a melting point of 1083℃. All failures are caused by local circuit overheating (Joule's Law).
Three Core Causes
1. Short Circuit: Contact of live, neutral or ground wire causes a current surge and ultra-high-temperature arcs (over 3000℃) that burn wires instantly.
2. Overload: Overuse of high-power appliances exceeds the wire's safe current load. Accumulated heat over 250℃ melts and ignites the insulation.
3. Poor Contact: Loose or oxidized joints raise local resistance, leading to concentrated high temperature and wire ablation.
Risk Accelerators: Circuit aging, irregular wiring, undersized wires, external damage, moisture and corrosion.
Warning Signs (Power off immediately): Burnt rubber smell, sticky/discolored wire sheath, abnormal joint noise, frequent tripping.
