NCCER Electrical Level 2 Module 9 'Grounding and Bonding'

NEC Article 250 ______.

is the primary governing article for the proper use and installation of grounding and bounding.

Suppose a loose connection has been exposed bare conductor and it contacts the edge of a metal enclosure. Is this an example of a short circuit or a ground fault?

ground fault

A single-phase system has two legs, Leg A and Leg B. If Leg A is carrying 50A and Leg B is carrying 45A, the current carried by the neutral is _____.

50A-45A=5A (Leg A- Leg B)

Assuming the use of 75 degrees Celsius copper conductors, a 200A commercial services would require?

3/0 service conductors

A ground rod must be installed in a coastal location and can only be driven halfway before encountering a rock shelf. One alternative is to _____.

burry the rod in a trench at least 30" (750 mm) deep

The EGC for a flexible metal conduit connection to a motor supplied with a 20A circuit____.

12 AWG copper

When using nonmetallic boxes with type NM cable, the grounding wire _____.

is not required to be connected to the box

When grounding at more than one building, the GEC at the second building is sized using _____.

NEC Table 250.66

If the voltage drop between a grounding electrode and an auxiliary potential electrode is 10V and a current of 10A is passed between an auxiliary current electrode and the grounding electrode, the resistance is __.

1 ohm

When completing a three-point test, the potential electrode is placed at ____.

62% of the current electrode distance

Item B in Figure RQ01 represents the _____.

ungrounded conductors (Hot)

Item E in Figure RQ01 represents the _____.

grounding electrode conductor

Item C in Figure RQ01 represents the _____.

grounded conductor (Neutral)

Item F in Figure RQ01 represents the _____.

main bonding jumper

The conducting connection, whether intentional or accidental, between any of the conductors of an electrical system is known as a ____.

short circuit

Which conductor(S) are grounded on a single-phase, three-wire, 120/240V system?

Neutral

Residential electrical services are grounded by connecting the grounded conductor to a grounding electrode at the _____.

neutral bus in the main panelboard

A single-phase system has two legs, Leg A and Leg B. If Leg A is carrying 35A and Leg B is carrying 30A, the current carried by the neutral is ____.

35A-30A=5A (Leg A - Leg B)

A concrete-encased electrode used for service grounding must be covered with a minimum of ____.

2" (50 mm) of concrete

Which of the following is an NEC violation when used as a grounding electrode?

An underground gas line

The maximum distance allowed by the NEC to connect a grounding conductor to a water pipe after the pipe enters the building is ___.

10' (3 m)

Which of the following is used to connect a ground rod with a grounding conductor?

A grounding clamp

All of the following are suitable materials for ground rods, except ____.

A. Stainless steel

B. galvanized steel

C. iron

D. aluminum

D. aluminum

Which of the following copper AWG sizes should be used for the grounding conductor for a 200A service using 3/0 copper conductors?

No. 4

Assuming the use of 75 degrees Celsius copper conductors, a 230A commercial services would require?

4/0 service conductors

When a metal water pipe is used as a grounding electrode, what must be provided around the water meter?

Bonding jumper

The EGC for a flexible metal conduit connection to a motor supplied with a 15A circuit is ____.

14 AWG copper

The main bonding jumper for 4/0 service conductors is ___.

2 AWG copper

If you are bounding multiple disconnects and the size of the service-entrance conductor is 3/0, the size of the bonding jumper is ____.

4 AWG copper

Touch voltage extends to a distance of approximately ___.

3' (1 m)

A short circuit is a conducting connection, whether international or accidental, between any of the _____ of an electrical system.

conductors

True or False? The neutral or (grounded) conductor is a system or circuit conductor that is intentionally grounded.

True

A conductor used to connect equipment or the grounded circuit of a wiring system to a grounding electrode is called a(n) ____ conductor.

grounding electrode

The two types of grounding systems are system grounding and _____.

equipment grounding

If the loads were only 240V on a single-phase 240V system with a center-tapped transformer, the neutral conductor would carry_______ amperes.

0

Systems less than 50V are required to be grounded if the supply voltage to the transformer exceeds__________ to ground.

150V

Circuits that cannot be grounded include certain circuits for cranes, electrolytic cells, secondary circuits on lighting systems, and isolated power systems in _______.

Healthcare Facilities

Systems are solidly grounded to limit the __________ during normal operation and to prevent excessive voltages due to lightning and line surges.

voltage to ground

Grounding methods include an underground water pipe in direct contact with the earth for no less than ___________.

10'

The size of the grounding electrode conductor is based on the size of the _____.

service entrance conductors

The size of the EGC is determined by the _____.

size of overcurrent device that is protecting the system

All receptacles used in residential applications must be of the___________ type.

grounding

Electrical ____ is the key to successful clearing of ground faults.

continuity

The size of the bonding jumper on the supply side is based on the size of the ____ in each raceway.

service entrance conductor

The two main purposes of the neutral in a grounded system are to permit utilization of power at line-to-neutral voltage and _______.

To provide low impendence return path for flow of fault current to the source and to facilitate the operation of the overcurrent devices in the circuit.

When a main bonding jumper is required by the NEC, the jumper ____.

cannot be less than 12.5% of the area of the largest phase conductor.

An acceptable grounding electrode is a(n) _____.

metal frame of a building which is effectively grounded

Rod, pipe, and plate electrodes must have a resistance to ground of at least ____.

25 ohms or less.

Ultimately, the ground fault is cleared when the ______.

Over current devices are opened

Which type of system is required to be grounded?

AC Systems over 1K Volts

The minimum length allowed for driven ground rods under normal conditions is _____.

8'

The minimum diameter of galvanized pipe allowed for a grounding electrode is _____.

3/4"

Where there is a requirement to add a second grounding electrode, the two electrodes must be spaced at least _____.

6' apart

A ground ring consisting of 20' of No.2 bare copper must be buried no less than _____.

2.5' below grade

A ground test utilizing an earth ground resistance tester is known as the _____.

3 point method

Grounding requirements for AC systems are contained in _____.

NEC sections 250.20 and 250.21

Which of the following describes bounding?

Connecting to establish electrical continuity and conductivity.

Plate electrodes made of copper must be at least _____.

0.06" thick

The unintentional electrically conducting connection between an ungrounded conductor, of an electrical circuit and the normally noncurrent-carrying conductors, metallic enclosures, metallic equipment, or the earth

Gounod Fault=

Equipment grounding refers to connecting the normally noncurrent-carrying metal parts of equipment to the system grounded conductor and/or _____.

The grounding electrode conductor

In a separately derived system, the equipment bonding jumper connects _____.

system housing to the neutral bus bar