Loose connections at the circuit breaker terminals, where the wire is secured to the breaker, or at the bus bar connections can generate enough heat to melt the insulation right inside the panel enclosure. This type of failure is concerning because of the high available fault. A melted electrical wire indicates a severe failure of the conductor's insulation due to excessive thermal stress. Understanding the causes of melted outlets and connectors, implementing preventive measures, and. The National Electrical Code (NEC), in partnership with the National Fire Protection Association (NFPA), monitors the safety of electrical wiring in the United States.