Master Electrician Practice Exam

For a grounded electrical system supplied by a feeder or branch circuit, the equipment grounding conductor is sized according to what?

1. the voltage rating

2. the maximum load

3. the overcurrent protective device

4. the wire insulation type

The correct answer is: the overcurrent protective device

The correct choice reflects that the equipment grounding conductor must be sized in accordance with the rating of the overcurrent protective device (OCPD). This is significant because the OCPD is designed to protect the circuit from excess current that could cause overheating or a potential fire hazard. The grounding conductor provides a path for fault currents to travel back to the source, ensuring that the OCPD can operate effectively to interrupt the circuit during a fault condition. When considering the sizing based on the OCPD, electricians refer to established guidelines such as those outlined in the National Electrical Code (NEC), which stipulate specific ratios linking the size of grounding conductors to the ampacity of the overcurrent protective device. This sizing ensures that the grounding system is adequate to handle any fault currents without becoming a hazard itself. While other factors, like the voltage rating, maximum load, and wire insulation type, are important in overall circuit design and safety considerations, they do not directly dictate the size of the equipment grounding conductor. The OCPD rating is the critical factor that ultimately ensures safety and compliance with codes.