—(1) Every headlamp required to be carried by a motor vehicle by virtue of these Rules shall, when lit, show to the front of the vehicle a white light visible from a reasonable distance.
(2) Every headlamp fitted on or to a vehicle shall have its wiring arranged so that it can emit both main and dipped beams.
(3) It shall not be necessary for any headlamp fitted on or to any of the following vehicles to be capable of emitting a main beam:
a motor-cycle which is so constructed as to be incapable of exceeding a speed of 50 kilometres per hour; and
a locomotive which is so constructed as to be incapable of exceeding a speed of 40 kilometres per hour.
(4) No headlamp shall be used on a vehicle unless the headlamp is so constructed, fitted and maintained that the beam of light emitted therefrom can be extinguished by the operation of a device which at the same time causes a dipped beam to be emitted from the headlamp.