FREE Licensed Electrical Contractor Grounding and Bonding Questions and Answers

Question 1

An electrical service is supplied by 4/0 AWG copper service-entrance conductors.
According to NEC Table 250.66, what is the minimum size copper Grounding Electrode Conductor (GEC) required to connect to a metal underground water pipe electrode?

Accepted Answer

2 AWG

Answer

4 AWG

Answer

6 AWG

Answer

1/0 AWG

Question 2

What is the primary purpose of bonding all non-current-carrying metal parts of an electrical installation together?

Accepted Answer

To provide a low-impedance path for fault current to facilitate the operation of overcurrent devices.

Answer

To stabilize the system voltage to ground during normal operation.

Answer

To connect the electrical system to the earth to dissipate lightning strikes.

Answer

To reduce the effects of electromagnetic interference (EMI) on sensitive equipment.

Question 3

According to NEC 250.52(B), which of the following is expressly NOT permitted to be used as a grounding electrode?

Accepted Answer

A metal underground gas piping system.

Answer

The metal frame of a building that is effectively grounded.

Answer

A concrete-encased electrode with at least 20 feet of bare copper conductor.

Answer

A ground ring encircling the building or structure.

Question 4

A contractor is installing a branch circuit protected by a 60-amp circuit breaker. What is the minimum size copper Equipment Grounding Conductor (EGC) required for this circuit?

Accepted Answer

10 AWG

Answer

12 AWG

Answer

8 AWG

Answer

6 AWG

Question 5

When installing a separately derived system, such as a dry-type transformer, which component is required by NEC 250.30 to connect the system's grounded conductor (neutral) to the equipment grounding conductor(s)?

Accepted Answer

A system bonding jumper.

Answer

A ground rod installed within 5 feet of the transformer.

Answer

A supply-side bonding jumper.

Answer

An intersystem bonding termination.

Question 6

If an interior metal water piping system is not being used as a grounding electrode, but is required to be bonded, where must the bonding jumper be connected?

Accepted Answer

To any of the grounding electrodes, the service enclosure, or the grounded service conductor.

Answer

Only at the main water meter.

Answer

To the nearest branch circuit equipment grounding conductor.

Answer

Within 5 feet of where the water pipe enters the building.

An electrical service is supplied by 4/0 AWG copper service-entrance conductors.According to NEC Table 250.66, what is the minimum size copper Grounding Electrode Conductor (GEC) required to connect to a metal underground water pipe electrode?

An electrical service is supplied by 4/0 AWG copper service-entrance conductors.
According to NEC Table 250.66, what is the minimum size copper Grounding Electrode Conductor (GEC) required to connect to a metal underground water pipe electrode?