If a breaker is listed to accept two "hot" conductors, the configuration of two conductors under one screw:

When a breaker is specifically listed to accept two "hot" conductors, it means that the manufacturer has tested and approved this practice for that particular model of breaker. Therefore, applying two conductors under one terminal screw aligns with the manufacturer's guidelines and safety standards, indicating that this action is safe and compliant when performed correctly.

Two conductors can be connected under one terminal provided that the circuit is designed to accommodate this setup, ensuring that both conductors are of suitable size and that they both come from the same circuit or phase. This practice is not inherently problematic when performed with the proper equipment, following electrical codes and standards.

In contrast, situations where a breaker is not rated for two conductors could result in overheating or electrical failure, which is why being mindful of the breaker's specifications is essential. Hence, utilizing a breaker designed for dual conductors under one terminal is safe, ensuring the integrity of the electrical system and preventing potential hazards.