HOLT Electricians Practice Exam

What is the minimum overload protection ampere for a 1 horsepower, 120-volt motor rated at 14 amperes?

1. 14

2. 15

3. 16.1

4. 20

The correct answer is: 16.1

To determine the minimum overload protection for a 1 horsepower, 120-volt motor rated at 14 amperes, it is essential to refer to the National Electrical Code (NEC) and relevant motor protection standards. For motors, overload protection is typically based on the motor's full-load current rating, which in this case is 14 amperes. According to NEC guidelines, the overload protection device should be sized appropriately to avoid nuisance tripping while still providing adequate protection for the motor. The common practice is to set the overload protection between 125% and 150% of the motor's full-load current to ensure that the device allows for temporary overloads but protects the motor during sustained overload conditions. Calculating 125% of 14 amperes gives us 17.5 amperes, which means the overload protection device should be greater than this value to adequately protect the motor. Therefore, the next standard size above this figure is generally selected for practical applications, leading to a common choice of 20 amperes. While the answer indicated may suggest a number lower than 17.5 amperes, it's important to understand that proper sizing for protection must account for potential inrush and operational variations. Therefore, selecting an overload protection rated at