I. Any stop or turn signal when required herein shall be given either by means of the hand and arm or by lighted signal lamps, except as otherwise provided in paragraph II.
II. Any vehicle in use on a way shall be equipped with, and required signal shall be given by, lighted signal lamps when the distance from the center of the top of the steering post to the left outside limit of the body, cab or load of such vehicle exceeds 24 inches, or when the distance from the center of the top of the steering post to the rear limit of the body or load thereof exceeds 14 feet. The latter measurement shall apply to any single vehicle, and to any combination of vehicles.