For a conductor with a computed ampacity of 75 amps, what is the maximum standard ampere rating of the overcurrent protection device allowed?

To determine the maximum standard ampere rating of the overcurrent protection device for a conductor with a computed ampacity of 75 amps, it is essential to refer to the guidelines provided in the National Electrical Code (NEC) regarding overcurrent protection.

The overcurrent protection device must be sized based on the conductor's ampacity to ensure that it adequately protects the conductor without tripping unnecessarily. Generally, the maximum rating of the overcurrent protection device can exceed the ampacity of the conductor, but there are specific limits based on the calculated ampacity.

In this case, the computed ampacity is 75 amps. According to the NEC, for branch circuits with conductors rated at 60 amps or more, the overcurrent device can be sized at 125% of the conductor's ampacity or the next higher standard rating available. Therefore,

1. Calculating 125% of 75 amps gives 93.75 amps.

2. The next standard size for an overcurrent protection device above 75 amps while still within the allowable threshold is 80 amps.

However, since you want the highest standard rating up to this threshold, it leads to 80 amps being acceptable for a circuit where conductors are adequately protected without overly