Patent ID: 7031132

Claim:
A diagnostic tool for detecting the presence of an electrical short in an electrical circuit having a voltage supply with a maximum output voltage, the tool comprising: a positive temperature coefficient (PTC) member that protects the electrical circuit being diagnosed from excessive current, the PTC member being characterized in that: the PTC member is in a relatively low resistance state when current flowing through the PTC member is substantially less than a trip current value; the PTC member's resistance increases nonlinearly to a relatively high resistance state when current flowing through the PTC member exceeds the trip current value; and the PTC member has two electrical leads; the PTC member is adapted to be damaged by an overvoltage condition of 120 volts; a signaling apparatus having two electrical leads electrically connected in parallel with the two electrical leads of the PTC member, wherein the signaling apparatus emits a signal only when the PTC member is in a relatively high resistance state; and two electrically conducting spring-biased clamps electrically connected to the electrical leads of the PTC member for temporarily connecting the diagnostic tool to the electrical circuit.