Patent ID: 6946947

Claim:
A plug-in fuse for protecting electrical circuits, the fuse insertable and removable from a fuse holder, the fuse comprising: a main fuse body comprising a first body material allowing light transmission through at least a portion of the body; a fuse element disposed in an enclosed chamber in the body, the fuse element comprising a burnout portion, at least two terminals and at least two connecting portions connecting said at least two terminals to said burnout portion, the chamber enclosing the burnout portion of the fuse element; and a thermally-degradable material disposed on a portion of the body, the material being separated from the burnout portion by a thermally conducting airspace, the airspace being of a preselected distance sufficient to allow transfer of heat created upon the burnout of burnout portion, the heat causing the thermally degradable material to change color and cause dimensional irregularities on the material, the thermally degradable material further being in partial contact with the coupling portions away from the burnout portion, wherein a portion of the thermally degradable material, the airspace and the burnout portion are generally straight and parallel with each other.