An apparatus and method for flame sensing within a turbine. A sensor assembly, an electrical assembly and a cable assembly extending therebetween. A photodiode generates an electrical signal and the electrical assembly determines a characteristic. An inner conductor electrically connects the photodiode to the electrical assembly. A first insulating layer, with mineral insulation material, surrounds the inner conductor. An inner sheath, with electrically conductive material, surrounds the first insulating layer. A second insulating layer, with mineral insulation material, surrounds the inner sheath. An outer sheath, with an electrically conductive, metal material, surrounds the second insulating layer. The cable assembly is configured for use up to about 300 degrees Celsius or greater. The portions of the cable are constructed and configured, and connected between the sensor assembly and the electrical assembly, to enclose the inner conductor such that the inner conductor is not exposed outside of confines of the cable.