There is provided a system and a test instrument for identifying or verifying the fiber arrangement and/or the cable type of multi-fiber array cables (such as MPO cables) which employs a light source and a polarity detector at the near end of the multi-fiber array cable under test, and a loopback device at the far end. The polarity detector comprises light presence detectors used to detect which one of the optical fibers of the multi-fiber array cable returns light looped back at the far end and thereby determine the fiber arrangement and/or the cable type of the multi-fiber array cable.