Given a transformer with a primary rating of 1000 volts and rated primary amperage of 5 amps, the overcurrent protection device rating shall not exceed __________?

Given a transformer with a primary rating of 1000 volts and rated primary amperage of 5 amps, the overcurrent protection device rating shall not exceed __________?

• A. 5 amperes
• B. 8 amperes
• C. 10 amperes
• D. 12 amperes

Answer: (B)

To determine the maximum rating for the overcurrent protection device in this case, we utilize the transformer’s primary rating. According to the National Electrical Code (NEC), overcurrent protection for transformers should typically not exceed 125% of the rated primary current. Given that the transformer has a primary amperage of 5 amps, the calculation involves multiplying this value by 125%. 5 amps × 1.25 = 6.25 amps. When selecting an ampacity rating for the overcurrent protection device, it should be the next standard rating above 6.25 amps. The standard breaker sizes commonly available include 7 amps, 10 amps, and so forth, but the specific options must match what's typically used. In this case, while 7 amps would be ideal based on the calculation, if we round up to the nearest option available from the choices presented here, the correct choice would be 8 amperes, as that does not exceed the allowable overcurrent capacity while ensuring adequate protection for the transformer. Thus, the correct answer aligns with sound electrical engineering practices regarding the protection of transformers, ensuring that equipment is safeguarded against excessive currents that might cause overheating or damage.

To determine the maximum rating for the overcurrent protection device in this case, we utilize the transformer’s primary rating. According to the National Electrical Code (NEC), overcurrent protection for transformers should typically not exceed 125% of the rated primary current.

Given that the transformer has a primary amperage of 5 amps, the calculation involves multiplying this value by 125%.

5 amps × 1.25 = 6.25 amps.

When selecting an ampacity rating for the overcurrent protection device, it should be the next standard rating above 6.25 amps. The standard breaker sizes commonly available include 7 amps, 10 amps, and so forth, but the specific options must match what's typically used.

In this case, while 7 amps would be ideal based on the calculation, if we round up to the nearest option available from the choices presented here, the correct choice would be 8 amperes, as that does not exceed the allowable overcurrent capacity while ensuring adequate protection for the transformer.

Thus, the correct answer aligns with sound electrical engineering practices regarding the protection of transformers, ensuring that equipment is safeguarded against excessive currents that might cause overheating or damage.