All measurements on lamps equipped with non-replaceable light sources shall be made at 6.3 V or 6.75 V (optionally for cornering lamps only), 13.2 V or 13.5 V (optionally for cornering lamps only) or 28.0 V or at other vehicle voltage as specified by the applicant. The test laboratory may require from the applicant the special power supply needed to supply the light sources. The test voltages shall be applied to the input terminals of the lamp. a0c0