A system for power and bidirectional data transmission between a main unit and a remote unit via a plurality of wires during a predetermined time period for an uplink transmission, the system comprising: a plurality of wires coupled between the main unit and the remote unit; the main unit comprising: a signal generator coupled to the plurality of wires and providing a three phase digital signal transmitted from the main unit to the remote unit via the plurality of wires, wherein each digital signal of the three phase digital signal is coupled to a respective wire (L1, L2 or L3) of the plurality of wires; and the remote unit comprising: a line selector coupled to the plurality of wires: for selecting two wires of the plurality of wires for transmitting DC power from the main unit to the remote unit during the predetermined time period for an uplink transmission; and for selecting the wire (L1, L2 or L3) of the plurality of wires not chosen for DC power transmission, for an uplink transmission from the remote to the main unit during the predetermined time period for an uplink transmission, wherein the selected wire transmits one digital signal of the three phase digital signal from the main to the remote unit; and a modulator coupled to the wire selected for the uplink transmission for modulating the respective digital signal received from the main unit with digital uplink data during the predetermined time period for an uplink transmission. a plurality of wires coupled between the main unit and the remote unit; the main unit comprising: a signal generator coupled to the plurality of wires and providing a three phase digital signal transmitted from the main unit to the remote unit via the plurality of wires, wherein each digital signal of the three phase digital signal is coupled to a respective wire (L1, L2 or L3) of the plurality of wires; and a signal generator coupled to the plurality of wires and providing a three phase digital signal transmitted from the main unit to the remote unit via the plurality of wires, wherein each digital signal of the three phase digital signal is coupled to a respective wire (L1, L2 or L3) of the plurality of wires; and the remote unit comprising: a line selector coupled to the plurality of wires: for selecting two wires of the plurality of wires for transmitting DC power from the main unit to the remote unit during the predetermined time period for an uplink transmission; and for selecting the wire (L1, L2 or L3) of the plurality of wires not chosen for DC power transmission, for an uplink transmission from the remote to the main unit during the predetermined time period for an uplink transmission, wherein the selected wire transmits one digital signal of the three phase digital signal from the main to the remote unit; and a modulator coupled to the wire selected for the uplink transmission for modulating the respective digital signal received from the main unit with digital uplink data during the predetermined time period for an uplink transmission. a line selector coupled to the plurality of wires: for selecting two wires of the plurality of wires for transmitting DC power from the main unit to the remote unit during the predetermined time period for an uplink transmission; and for selecting the wire (L1, L2 or L3) of the plurality of wires not chosen for DC power transmission, for an uplink transmission from the remote to the main unit during the predetermined time period for an uplink transmission, wherein the selected wire transmits one digital signal of the three phase digital signal from the main to the remote unit; and for selecting two wires of the plurality of wires for transmitting DC power from the main unit to the remote unit during the predetermined time period for an uplink transmission; and for selecting the wire (L1, L2 or L3) of the plurality of wires not chosen for DC power transmission, for an uplink transmission from the remote to the main unit during the predetermined time period for an uplink transmission, wherein the selected wire transmits one digital signal of the three phase digital signal from the main to the remote unit; and a modulator coupled to the wire selected for the uplink transmission for modulating the respective digital signal received from the main unit with digital uplink data during the predetermined time period for an uplink transmission.