CEP Safety Standards & Compliance 5

Question 1

Which NEC section requires arc-fault circuit interrupter (AFCI) protection for branch circuits supplying outlets in dwelling unit bedrooms?

Accepted Answer

NEC 210.12

Answer

NEC 210.12 requires AFCI protection for branch circuits supplying outlets in bedrooms and, in recent editions, most living spaces of dwelling units.

Question 2

What is the significance of the 'available fault current' calculation when designing an electrical system?

Accepted Answer

It ensures that all overcurrent devices are rated to interrupt the maximum possible short-circuit current

Answer

Available fault current calculations ensure that every overcurrent protective device has sufficient interrupting capacity to safely clear a bolted short-circuit fault without catastrophic failure.

Question 3

According to NFPA 70B, what is the recommended frequency for thermographic (infrared) inspections of electrical switchgear in industrial facilities?

Accepted Answer

Annually, or more frequently in harsh environments

Answer

NFPA 70B recommends annual thermographic inspections of electrical equipment, with more frequent inspections in harsh or high-duty-cycle environments.

Question 4

Under NEC Article 430, what is the maximum allowable size of an inverse time circuit breaker used as the branch-circuit short-circuit and ground-fault protective device for a motor with a full-load current of 20A?

Accepted Answer

250% of FLA = 50A

Answer

NEC 430.52 Table allows an inverse time circuit breaker to be sized up to 250% of motor full-load amperes for short-circuit protection, giving a maximum of 50A for a 20A FLA motor.

Question 5

What is the purpose of the 'flash hazard analysis' or incident energy analysis required by NFPA 70E?

Accepted Answer

To calculate the incident energy at a worker's face and hands so appropriate PPE can be selected

Answer

The incident energy analysis calculates the thermal energy released at a working distance during an arcing fault so that PPE with a sufficient arc rating can be selected to protect the worker.

(CEP) Certified Electrical Professional Practice Test

(CEP) Certified Electrical Professional Practice Test

CEP Safety Standards & Compliance 5