A motor vehicle, except a commercial vehicle as defined in section 28-2231, may be operated under the conditions specified in section 28-922 when it is equipped with two lighted lamps that are on the front of the motor vehicle and that are capable of revealing persons and objects seventy-five feet ahead in lieu of lamps required in section 28-941 or 28-943, but the motor vehicle shall not be operated at a speed of more than twenty miles per hour.
A.R.S. § 28-945