The maximum breaker rating must _____ the allowable ampacity of the conductor.

The maximum breaker rating must not exceed the allowable ampacity of the conductor to ensure safety and proper function in the electrical system. This principle exists to prevent overheating and potential fire hazards that can arise from using a breaker with a rating too high for the conductors. If a breaker is rated higher than the conductors' ampacity, it may not trip during an overload condition. This delay or failure in tripping can cause the conductors to carry too much current, leading to insulation breakdown and increased risks of short circuits or fires.

In contrast, having a breaker rating that is equal to or exceeds the conductor’s ampacity does not provide the necessary protection. Proper matching of breaker ratings with the allowable ampacity of conductors ensures that the entire system is safe and functionally reliable, adhering to electrical codes and practices.