What are the Causes of an Electrical Connection Melt? | Hunker Short Circuits. If this happens, a fuse generally blows, cutting the electrical supply before an electrical connection melts. However, if the fuse does not blow and electricity continues to flow, the wires will get hot. The heat will then melt the outer plastic coating, which may cause it to catch on fire. Fuse-Melt-Down - Gonzo's Tool Box Both edges of the fuse in this Suburban were melted down around the metal prongs that go into the fuse box. It was practically glued to the fusebox and it took the better part of the afternoon to free it from the box.