Master Electrician Practice Exam

If a cablebus system is rated at 95 amperes, what is the maximum allowable rating of the overcurrent device protecting it?

1. 90 amperes

2. 95 amperes

3. 100 amperes

4. 105 amperes

The correct answer is: 100 amperes

The maximum allowable rating of the overcurrent device protecting a cablebus system rated at 95 amperes should be determined based on the National Electrical Code (NEC) guidelines. According to NEC, an overcurrent device must not exceed 125% of the continuous load. In this case, if the cablebus system is rated at 95 amperes, the maximum rating for the overcurrent device would be calculated as follows: 1. Calculate 125% of 95 amperes: - 95 A × 1.25 = 118.75 A Since overcurrent devices are available in standard ratings, the next available standard rating that does not exceed 118.75 A is 100 amperes. This ensures that the protection device adequately protects the cablebus system without allowing for overloading beyond its rated capacity. Choosing 100 amperes as the rating creates a safe operating environment while complying with the NEC requirements. Therefore, the maximum allowable rating of the overcurrent device protecting a cablebus system rated at 95 amperes is appropriately set at 100 amperes.