Multiple embodiments of a device suitable for arrangement in a circuit for protection of components in the circuit are disclosed, the device of each embodiment including a temperature responsive electrical regulating component including a conductive polymer or ceramic material having an electrical regulating capability dependent on temperature and at least one series connected switch including trip means also responsive to temperature for opening and closing the circuit in a reliable manner, the device being adapted for connection in the circuit to be protected. The various embodiments include different arrangements of the temperature responsive electrical regulating component and the switch. Certain of the embodiments include a second series connected switch of similar construction. The conductive polymer or ceramic material can be of a variety of types for performing different electrical regulating functions within the circuit.