How many amps should the overcurrent protection be on an electric motor rated for 12 amps and 120 volts?

• A. 10 amps
• B. 15 amps
• C. 20 amps
• D. 25 amps

Answer: (B)

The correct answer is based on the National Electric Code (NEC) guidelines for overcurrent protection for motors. For electric motors, the recommended overcurrent protection is typically set at 125% of the motor's full-load current. In this case, the motor is rated for 12 amps.

To calculate the appropriate amperage for overcurrent protection, you multiply the full-load current by 125%. This would be calculated as follows:

12 amps x 1.25 = 15 amps.

Choosing 15 amps for overcurrent protection provides the necessary safeguard against potential overloads while also ensuring the motor operates efficiently without frequent tripping. This is a standard practice for protecting motors from irreversible damage that could occur due to excessive current.

The other options either provide less protection, which may not be adequate for the motor's needs, or they exceed the recommended limit which can result in unnecessary outages or potential harm to the motor. Therefore, 15 amps is the optimal choice for overcurrent protection in this scenario.