Parallel single-conductor cables are used to increase the total current-carrying capacity (ampacity) of a circuit. While they provide flexibility, they introduce critical technical challenges that must be managed to ensure a safe and reliable system.

1. Unequal Current Sharing: If the conductors in a parallel set have different impedances, they will carry unequal currents. This can be caused by differences in conductor length, material, or termination, but the most common cause is an unsymmetrical physical arrangement of the cables. The conductor with the lower impedance will carry more current, leading to overheating, energy loss, and potential failure.

2. Induced Currents and Heating: Each single conductor in an AC circuit generates a magnetic field. If the conductors are not properly arranged, these fields can induce circulating currents in nearby metallic conduits, trays, or even the cable's own metallic sheath. These induced currents cause significant heating and wasted energy.

3. Cross-Phasing and Phasing Errors: When multiple sets of single conductors are installed, it is critical to maintain the correct phase sequence (e.g., A-B-C, A-B-C) to ensure the magnetic fields of the different phases cancel each other out. Incorrect phasing can lead to significant inductive reactance, voltage drops, and overheating.