Licensed Electrical Contractor FREE Licensed Electrical Contractor Grounding and Bonding Questions and Answers 2

Question 1

What is the minimum size copper grounding electrode conductor required for a 400-ampere service per NEC Article 250?

Accepted Answer

1/0 AWG

Answer

2/0 AWG

Answer

3/0 AWG

Answer

4/0 AWG

Question 2

When a metal water pipe is used as a grounding electrode, it must be supplemented by an additional electrode unless the pipe meets which condition?

Accepted Answer

No supplemental electrode is ever required with metal water pipes

Answer

It is at least 10 feet in direct contact with the earth

Answer

It is copper pipe with a minimum 1-inch diameter

Answer

It is connected to a ground rod within 5 feet of entry

Question 3

What is the maximum resistance to ground permitted for a single ground rod before a supplemental electrode must be installed?

Accepted Answer

25 ohms

Answer

10 ohms

Answer

15 ohms

Answer

20 ohms

Question 4

In a commercial building, where must the bonding jumper for a metal raceway containing service-entrance conductors be connected?

Accepted Answer

At each end and at every pull point

Answer

At any convenient point along the raceway

Answer

Only at the service equipment end

Answer

Only at the meter base end

Question 5

What type of connection is prohibited for grounding electrode conductor splices unless it is an irreversible compression type?

Accepted Answer

Wire nut connectors

Answer

Bolted connections

Answer

Exothermic welds

Answer

Listed split-bolt connectors

Question 6

According to the NEC, what is the purpose of an equipment bonding jumper on the supply side of a service?

Accepted Answer

To ensure an effective ground-fault current path for overcurrent device operation

Answer

To carry normal load current during operation

Answer

To reduce voltage drop in branch circuits

Answer

To provide a low-impedance path for lightning strikes only