FREE TN-LLE Grounding and Bonding Questions and Answers

Question 1

Which of the following is NOT permitted to be used as a grounding electrode according to NEC 250.52(B)?

Accepted Answer

An underground metal gas piping system

Answer

A metal underground water pipe in direct contact with the earth for 10 feet

Answer

A concrete-encased electrode ('Ufer' ground)

Answer

A rod electrode driven 8 feet into the earth

Question 2

If a single rod electrode is installed and its resistance to ground is greater than 25 ohms, what does NEC 250.53(A)(2) require?

Accepted Answer

A second grounding electrode must be installed.

Answer

The rod must be driven to a depth of 10 feet.

Answer

The soil around the rod must be treated with chemicals.

Answer

A larger diameter ground rod must be used.

Question 3

What is the minimum size copper grounding electrode conductor (GEC) required for a service with 4/0 AWG copper service-entrance conductors?

Accepted Answer

2 AWG

Answer

6 AWG

Answer

4 AWG

Answer

1/0 AWG

Question 4

What is the primary purpose of a main bonding jumper at the service equipment?

Accepted Answer

To connect the equipment grounding conductor to the grounded (neutral) conductor

Answer

To bond the neutral bar to the grounding electrode

Answer

To bond the metal water piping system to the panel enclosure

Answer

To serve as the grounding electrode conductor

Question 5

A bonding jumper is required to be installed around a water meter on a metallic water piping system when that system is used as a grounding electrode. Why?

Accepted Answer

To ensure continuity of the grounding path if the meter is removed

Answer

To protect the water meter from electrical surges

Answer

To satisfy local plumbing code requirements

Answer

To reduce water pressure fluctuations

Question 6

When running a feeder to a detached building that includes an equipment grounding conductor, how must the grounded (neutral) and grounding conductors be treated at the detached building's subpanel?

Accepted Answer

They must be isolated from each other.

Answer

They must be bonded together at the subpanel.

Answer

The grounded (neutral) conductor must be connected to a separate ground rod.

Answer

Only the grounded (neutral) conductor is required.