ch 4

Question 1

The ? provides the essential function of connecting the electrical system, equipment, or both to the earth.

Answer 1

grounding electrode

Question 2

Which part of Article 250 provides the requirements for grounding electrodes and the grounding electrode system?

Answer 2

part III

Question 3

The purpose of a grounding electrode is to function as the connection between the ground (Earth) and grounded electrical systems and electrical equipment.

Answer 3

true

Question 4

Foundations and footings that are not in direct contact with the Earth qualify as grounding electrodes.

Answer 4

false

Question 5

Section 250.50 requires that all grounding electrodes that are present at each building or structure served be bonded together to form the grounding electrode system.

Answer 5

true

Question 6

The resistance between a grounding electrode (such as a ground rod) and Earth can vary depending on which of the following?

Answer 6

Ambient temperature

Geographical location

Mineral content of the soil

Question 7

A metal underground water pipe that is in direct contact with the Earth for ? or more is a code-recognized as a grounding electrode and must be included in the grounding electrode system.

Answer 7

10 feet

Question 8

Which of the following is not permitted as a grounding electrode?

Answer 8

Underground metal gas piping

Question 9

The NEC makes it clear that if any grounding electrodes are present at a building or structure served by electrical power, the electrodes must be bonded together to form a grounding electrode system.

Answer 9

true

Question 10

The NEC requires that a metal underground water pipe electrode be buried not less than 30 inches below grade level.

Answer 10

false

Question 11

The NEC generally prohibits the use of an interior metal water piping system to connect grounding electrodes to the grounding electrode conductor beyond a distance of ? from the point of entrance to the building or structure.

Answer 11

5 feet

Question 12

A concrete-encased electrode can be installed in either a vertical or horizontal orientation, and it must have not less than ? of one or more conductive rebar or rods, or a 4 AWG bare copper conductor.

Answer 12

20 feet

Question 13

Where two services are installed on the same building as permitted in 230.2(A), they are required to be connected to the same grounding electrode system.

Answer 13

true

Question 14

A ground ring electrode must completely encircle a building or structure, be not less than 20 feet in length, and be buried not less than ? below the grade.

Answer 14

30 inches

Question 15

Which of the following persons was responsible for the research and development that eventually resulted in the NEC requirements for a concrete-encased electrode?

Answer 15

Herbert G. Ufer

Question 16

Plate electrodes must be buried not less than 24 inches below grade.

Answer 16

false

Question 17

Stainless steel rod electrodes generally must not be less than ? in diameter.

Answer 17

5/8 inch

Question 18

A plate electrode is required to have not less than ? of surface in direct contact with the Earth.

Answer 18

2 square feet

Question 19

A single grounding electrode of the rod, pipe, or plate type must generally be supplemented by an additional electrode of any type specified in Section 250.52(A)(2) through (8).

Answer 19

true

Question 20

A single grounding electrode of the rod, pipe, or plate type is not required to be supplemented by an additional electrode of any type specified in Section 250.52(A)(2) through (8) if the single electrode has a resistance to earth of ? .

Answer 20

1 -5-25 ohms

Question 21

The supplemental grounding electrode for a metal water pipe electrode is permitted to be bonded to the grounding electrode conductor, the grounded service-entrance conductor, the nonflexible grounded service raceway, or any grounded service enclosure.

Answer 21

true

Question 22

A rod or pipe electrode is generally required to be driven to a depth of not less than ? .

Answer 22

8 feet

Question 23

A rod or pipe electrode that cannot be driven into the Earth because of encountering rock bottom is permitted to be buried at a depth of not less than ? .

Answer 23

30 inches

Question 24

A distance of not less than ? shall be maintained between an eight-foot ground rod and the next closest ground rod.

Answer 24

6 feet

Question 25

Where an auxiliary grounding electrode is installed for equipment such as parking lot light poles, the connection of the auxiliary electrode is in addition to the required ? .

Answer 25

equipment grounding conductor

Question 26

A ground rod electrode is always required to be driven into the Earth.

Answer 26

false

Question 27

The grounding electrode network for a lightning protection system is permitted to be used as the grounding electrode system for the electrical service supplying a building or structure only when there are no other electrodes available.

Answer 27

false

Question 28

A conducting object through which a direct connection to Earth is established defines which of the following?

Answer 28

Grounding electrode

250.52(a)

Question 29

What is the maximum resistance to ground permitted for a grounding electrode system consisting of a concrete-encased electrode, building steel electrode, and metal water pipe electrodes?

Answer 29

No maximum resistance value is specified in the NEC

Question 30

If present at each building or structure served, which of the following shall be bonded together to form the grounding electrode system?

Answer 30

Concrete-encased grounding electrode

Metal in-ground support structures

Metal underground water pipe electrode

Rod and pipe electrodes

Question 31

What is the minimum length of contact that must be made with the Earth in order for a metal in-ground support structure to qualify as a grounding electrode?

Answer 31

10 feet

Question 32

Where bonding jumpers are used to connect grounding electrodes together to form a grounding electrode system, ? shall be used to size the bonding jumpers.

Answer 32

Table 250.66

Question 33

If present, the structures and structural reinforcing steel described in Section 680.26(B)(1) and (B)(2) are required to be included in the grounding electrode system for a building or structure.

Answer 33

false

Question 34

A structure is defined as that which is constructed or built and does not include electrical equipment.

Answer 34

true

Question 35

The minimum sizing requirements for grounded conductors are provided in which of the following?

Answer 35

250.102