in a predetermined spaced apart relationship within the envelope 1 so as to provide for electrical insulation within the protector the movable electrode 3a comprises a bimetal blade 3b which is welded to lead in wire 3 at the end thereof the bimetal blade 3b is set to open upon reaching a predetermined temperature in the range of 140 u00b0 to 160 u00b0 c electrical contacts 8 and 9 are welded to the leading end of the stationary electrode 4a and the leading end of the bimetal blade 3b such electrical contacts are conventionally formed of silver or with silver coatings referring now to fig2 and 3 the bulbous envelope 1 is shown with the ptc heater and electrical connection devices a first sleeve 14 is snapped around the bulbous portion of the envelope 1 and is disposed adjacent to the press seal area 1a the first sleeve 14 can be made of any conventional electrically conductive material of sufficient resiliency to enable it to firmly grasp the envelope 1 such metals include copper and nickel plate copper a second sleeve 12 is disposed about the bulbous portion of the envelope 1 and in a heat transmitting relationship therewith preferably the radius of the first sleeve 14 is substantially identical to that.