Normally open, thermal sensitive electrical switching device

A temperature sensitive, electrical switching device, having first and second current carrying electrical leads, for completing an electrical circuit between the first and second electrical leads when the temperature of the switching device exceeds a predetermined temperature level, comprising:

• a hollow electrically conductive case having a first end defining an opening into a central cavity and a second end which is closed, said case being electrically connected to said first electrical lead,
• an electrically conductive member electrically connected to said second lead,
• non-conductive means for mounting said conductive member such that it extends into said central cavity, said non-conductive means sealing said opening into said cavity,
• a heat fusible electrically conductive pellet, dimensioned to engage said electrically conductive member without electrically contacting said electrically conductive case, said pellet being fusible at said predetermined temperature level to form a volume of electrically conductive liquid sufficient to establish an electrically conductive path between said case and said member,
• non-conductive spacer means positioned in said cavity adjacent said heat fusible pellet, and
• compression spring means in said cavity for urging said non-conductive spacer means against said heat fusible pellet such that said pellet will melt completely at said predetermined temperature level, whereby an open electrical circuit will exist between said first and second electrical leads until said predetermined temperature level is reached and a closed electrical circuit will be formed thereafter between said first and second electrical leads as said spring means and spacer means crush said pellet to insure uniform temperature activation.