Among the conductors listed below, all except ___ are permitted to be connected in parallel.

In electrical installations, certain conductors have guidelines regarding whether they can be connected in parallel to ensure safe and efficient operation. The practice of connecting conductors in parallel is typically restricted to certain sizes and types of wires, considering factors such as their ampacity, physical characteristics, and the potential for overheating.

The 1 AWG conductors are not typically permitted to be connected in parallel because they do not meet the necessary criteria laid out by standards that ensure secure electrical performance when multiple conductors are combined. Larger conductors like 4 AWG, 2 AWG, and 6 AWG can be connected in parallel since they allow for a balanced load distribution and sharing of current without the significant risks that smaller conductors would incur under similar conditions.

It's important for electrical professionals to understand the limitations and specifications of different conductor sizes, as improper configurations can lead to overheating, electrical failures, or safety hazards. This understanding helps maintain compliance with electrical codes and ensures the reliability of electrical systems.