NEC grounding and bonding requirements Quiz…

Q: Which of the following is NOT a permissible method for grounding an electrical system, as per the NEC?

Connecting to a driven ground rod with a resistance exceeding 25 ohms — NEC generally requires a ground rod's resistance to be 25 ohms or less. If higher, you need a second electrode.

Q: What is the primary purpose of bonding in an electrical system according to the NEC?

To provide a low-impedance path for fault current to flow back to the source — Bonding ensures a fast and reliable path for fault current, which allows overcurrent devices to quickly trip.

Q: In a separately derived system (e.g., a transformer), where should the neutral and grounding conductors be bonded?

At the secondary side of the transformer and nowhere else — The neutral and ground are bonded at the source (secondary) of the transformer. This is a single point bond.

Q: What is the minimum size of a copper grounding electrode conductor (GEC) required for a service with 400 kcmil copper service-entrance conductors, according to the NEC?

1/0 AWG — Refer to NEC Table 250.66. The GEC size is determined by the size of the service entrance conductors.

Q: Which of the following metallic components typically requires bonding in a residential electrical installation?

Metal gas piping — Metal gas pipes must be bonded to the electrical system ground to mitigate shock hazards.

Question 1 of 5

Which of the following is NOT a permissible method for grounding an electrical system, as per the NEC?

NEC generally requires a ground rod's resistance to be 25 ohms or less. If higher, you need a second electrode.

Question 2 of 5

What is the primary purpose of bonding in an electrical system according to the NEC?

Bonding ensures a fast and reliable path for fault current, which allows overcurrent devices to quickly trip.

Question 3 of 5

In a separately derived system (e.g., a transformer), where should the neutral and grounding conductors be bonded?

The neutral and ground are bonded at the source (secondary) of the transformer. This is a single point bond.

Question 4 of 5

What is the minimum size of a copper grounding electrode conductor (GEC) required for a service with 400 kcmil copper service-entrance conductors, according to the NEC?

Refer to NEC Table 250.66. The GEC size is determined by the size of the service entrance conductors.

Question 5 of 5

Which of the following metallic components typically requires bonding in a residential electrical installation?

Metal gas pipes must be bonded to the electrical system ground to mitigate shock hazards.

NEC grounding and bonding requirements Quiz