A method of qualifying a conductor for low-voltage DC power transmission, wherein the conductor has at least three wires, comprising the steps of: feeding signals from a controller to termination ends of at least three wires of the conductor; determining in the controller a resistance value of a first wire loop consisting of an aggregate resistance of any two of the at least three conductor wires; determining in the controller a resistance value of a second wire loop consisting of an aggregate resistance of one of the wires used in determination of the first loop and a conductor wire not used in determination of the first wire loop; wherein the determining of the resistance value for each of the first wire loop and the second wire loop comprises subtracting a resistance for that wire loop measured by a source unit and a resistance for that wire loop measured by a receive unit; wherein the source unit comprises a current source and an amplifier, the measuring of the resistance for each of the first and second wire loops by the source unit comprising providing current excitation and measuring a voltage at points at which the amplifier of the source unit is coupled to the conductor wires of that wire loop; and wherein the receive unit comprises grounding resistors and an amplifier, the measuring of the resistance for each of the first and second wire loops by the receive unit comprising providing a current path between the conductor wires of the wire loop through the grounding resistors and routing a current between the conductor wires to measure the resistance of the current path, the measurement of the resistance of the current path comprising measuring a voltage at points at which the amplifier of the receive unit is coupled to the conductor wires of that wire loop; determining in the controller a resistance difference between first and second wires of the conductor by determining a difference in resistance values between the first and second wire loops, wherein the first wire is the other of the wires used in the determination of the first loop and the second wire is the conductor wire not used in determination of the first wire loop; and qualifying the conductor for low-voltage DC power transmission when the resistance difference between the first and second wires is below a threshold. feeding signals from a controller to termination ends of at least three wires of the conductor; determining in the controller a resistance value of a first wire loop consisting of an aggregate resistance of any two of the at least three conductor wires; determining in the controller a resistance value of a second wire loop consisting of an aggregate resistance of one of the wires used in determination of the first loop and a conductor wire not used in determination of the first wire loop; wherein the determining of the resistance value for each of the first wire loop and the second wire loop comprises subtracting a resistance for that wire loop measured by a source unit and a resistance for that wire loop measured by a receive unit; wherein the source unit comprises a current source and an amplifier, the measuring of the resistance for each of the first and second wire loops by the source unit comprising providing current excitation and measuring a voltage at points at which the amplifier of the source unit is coupled to the conductor wires of that wire loop; and wherein the receive unit comprises grounding resistors and an amplifier, the measuring of the resistance for each of the first and second wire loops by the receive unit comprising providing a current path between the conductor wires of the wire loop through the grounding resistors and routing a current between the conductor wires to measure the resistance of the current path, the measurement of the resistance of the current path comprising measuring a voltage at points at which the amplifier of the receive unit is coupled to the conductor wires of that wire loop; determining in the controller a resistance difference between first and second wires of the conductor by determining a difference in resistance values between the first and second wire loops, wherein the first wire is the other of the wires used in the determination of the first loop and the second wire is the conductor wire not used in determination of the first wire loop; and qualifying the conductor for low-voltage DC power transmission when the resistance difference between the first and second wires is below a threshold.