Can direct current running in opposite directions in parallel wires increase the apparent resistance of a system? This is a real life problem that I’ve noticed on some electroforming equipment we relocated. Prior to the move the wires were separate. Now they are located in a conduit together. Using 500amps in two 4/0 cables per polarity running 70 feet in the conduit. 4/0 (or 0000 gauge) is a stranded 0.460” copper conductor with ~0.73” outer diameter with the insulation. Before the equipment move the system ran at about 16 volts. After the move it is running at about 22 volts. Can the magnetic fields created by the wires be interfering with the current flow? If there is an effect, how can it be calculated?