FREE NEC Grounding and Bonding Questions and Answers

Question 1

An electrician is installing a new 480/277V, 3-phase separately derived system from a transformer inside a building.
According to NEC 250.30(A), which of the following must be used as the grounding electrode for this new system?

Accepted Answer

The existing building or structure grounding electrode system

Answer

The nearest available metal water pipe

Answer

Two new 8-foot ground rods driven 6 feet apart

Answer

An isolated, dedicated ground plate buried near the transformer

Question 2

When installing an equipotential bonding grid for a permanently installed swimming pool, what is the MINIMUM size solid copper conductor required by NEC Article 680?

Accepted Answer

8 AWG

Answer

10 AWG

Answer

6 AWG

Answer

12 AWG

Question 3

A service is supplied by 500 kcmil copper ungrounded service-entrance conductors. If the only connection to the grounding electrode system is to two 8-foot ground rods, what is the MINIMUM size copper grounding electrode conductor (GEC) required?

Accepted Answer

6 AWG

Answer

1/0 AWG

Answer

4 AWG

Answer

2 AWG

Question 4

A main bonding jumper is being installed in a service panel. Its size is determined based on which of the following?

Accepted Answer

The size of the ungrounded service-entrance conductors

Answer

The rating of the main overcurrent protection device

Answer

The size of the grounding electrode conductor

Answer

The available fault current at the service

Question 5

Which of the following locations is a required point of attachment for bonding an interior metal water piping system in a building?

Accepted Answer

The service equipment enclosure

Answer

To the nearest metal structural frame of the building

Answer

To the equipment grounding conductor of the largest branch circuit

Answer

Within 10 feet of where the water pipe enters the building

Question 6

When bonding the structural steel of a building that is used as part of the grounding electrode system, the connection must be permanent, electrically continuous, and often achieved through which of the following means?

Accepted Answer

Embedded anchor bolts or reinforcing bars tied to a concrete-encased electrode

Answer

A listed pressure connector tightened to a painted column

Answer

A single clamp attached to a loose metal deck

Answer

A self-tapping screw into a steel stud

An electrician is installing a new 480/277V, 3-phase separately derived system from a transformer inside a building.According to NEC 250.30(A), which of the following must be used as the grounding electrode for this new system?

An electrician is installing a new 480/277V, 3-phase separately derived system from a transformer inside a building.
According to NEC 250.30(A), which of the following must be used as the grounding electrode for this new system?