Abstract: A two-unit device for identifying individual conductors in a multi-conductor installation having two ends. Each unit includes a telephone handset interposed in a series communication and continuity circuit. One of the units is a master unit and includes a multi-position switch for selecting individual conductors. The other unit is a slave unit and includes a set of LEDs. During operation, a person with the master unit selects a particular conductor by means of the switch, and an LED at the slave unit identifies the other end of the selected conductor. The two persons then communicate over the circuit being identified, and establish a label designation for the ends of the particular selected and identified conductor.