(a) Any stop or turn signal when required herein shall be given either by means of the hand and arm or by an electric turn signal device.
(b) A signal of intention to turn right or left shall be given during not less than the last one hundred (100) feet traveled by the vehicle before turning.
(c) The signals herein required shall be given either by means of the hand and arm or by a signal lamp or signal device, but when a vehicle is so constructed or loaded that a hand and arm signal would not be visible both to the front and rear of such vehicle then said signals must be given by such a lamp or device.
(d) All signals herein required given by hand and arm shall be given from the left side of the vehicle in the following manner and such signals shall indicate as follows:
(1) Left turn–Hand and arm extended horizontally.
(2) Right turn–Hand and arm extended upward.
(3) Stop or decrease of speed–Hand and arm extended downward.
(M.C. 1963, § 20.305.)