Any signal required by chapters 484A to 484E, inclusive, of NRS to be made by a driver when making a turn or a stop must be given either by means of a hand and arm or by a signal lamp or signal device of a type approved by the department, except if a vehicle is so constructed or loaded that a hand and arm signal would not be visible both to the front and rear of the vehicle, the signals must be given by a signal lamp or signal device.