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Plate electrodes shall be exposed not less than ______ inches below the surface of the earth. 250.53(7)

2 sq ft (0.186 sq m)

how much ohms must rod, pipes, and plate electrodes have?

25 ohms or less

what is the minimum length of a ground rod?

8 feet

pipe or conduit electrodes shall be not less than?

8' in length

2" (50mm) of concrete

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

Grounding electrode

A conducting object through which a direct connection to earth is established.

Grounding conductor

A conductor used to connect equipment or the grounded circuit of a wiring system to a grounding electrode or electrodes.

Grounding electrode conductor (GEC)

A conductor used to connect the system grounded conductor or the equipment to a grounding electrode or to a point on the grounding electrode system.

Grounding clip

A listed spring clip used to secure a bonding conductor to an outlet box.

Ground rod

A metal rod or pipe used as a grounding electrode.

Separately derived system

A premises wiring system whose power is derived from a source of electric energy or equipment other than a service. Such systems have no direct electrical connection, including a solidly connected ground circuit conductor, to supply conductors originating in another system.

5A

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?

Grounded conductor

A system or circuit conductor that is intentionally grounded.

aluminum

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

Supplemental electrode

An additional electrode (commonly a driven rod or pipe) required where the primary electrode is an underground metal water pipe in direct contact with the earth.

Effective ground fault path

An intentionally constructed, permanent, low-impedance electrically conductive path designed and intended to carry current under ground-fault conditions from the point of a ground fault on a wiring system to the electrical supply source and that facilitates the operation of the overcurrent protective device or ground-fault detectors on a high-impedance grounded system.

Short circuit

An often unintended low-resistance path through which current flows around, rather than through, a component or circuit.

4/0 service conductors

Assuming the use of 75 Celsius copper conductors, a 230A commercial service would require

Ungrounded conductors

Conductors in an electrical system that are not intentionally grounded

Bonding

Connected to establish electrical continuity and conductivity

Grounded

Connected to ground or to a conductive body that extends the ground connection.

Grounding connections

Connections used to establish a ground; they consist of a grounding conductor, a grounding electrode, and the earth surrounding the electrode.

what determines the size of the over current device

EGC electrical ground conductor

4AWG copper

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

System grounding

Intentional connection of one of the circuit conductors of an electrical system to ground potential.

The grounding conductor or neutral in a grounded system services two main purposes, give one purpose

It provides low-impedance return path for the flow of fault current to the source to facilitate the operation of the over current devices in the circuit

Ungrounded conductor

Item B in figure RQ01 represents the?

grounded conductor

Item C in figure RQ01 represents the ?

main bonding jumper

Item F in figure RQ01 represents the?

Auxiliary electrodes

Metallic electrodes pushed or driven into the earth to provide electrical contact for the purpose of performing measurements on grounding electrodes or ground grid systems.

NEC article 250, Part III

Methods for grounding an electric service

neutral bus in the main panelboard

Residential electrical service are grounded by connecting the grounded conductor to grounding electrode at the?

14 AWG copper

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

short circuit

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

Equipment grounding conductor (EGC)

The conductive path(s) that provide a ground-fault current path and connect normally noncurrent-carrying metal parts of equipment together and to the system grounded conductor, or to the grounding electrode conductor, or both.

Neutral conductor

The conductor connected to the neutral point of a system that is intended to carry current under normal conditions.

Main bonding jumper

The connection between the grounded circuit conductor and the equipment grounding conductor at the service.

Equipment bonding jumper

The connection between two or more portions of the equipment grounding conductor

Ground

The earth or a conducting connection to the earth.

2 AWG copper

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

5' (1.5m)

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

3' (1 m)

Touch voltage extends to a distance of approximately_______.

NEC Section 250.53(A)(1)

Upper end of rod must be below permanent moisture level

bonding jumper

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

grounding is required in which of the following situations

Where supplied by transformer exceeds 150V to ground

neutral

Which conductor(s) are grounded on a single-phase, three-wire,120/240Vsystem?

No. 4

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

An underground gas line

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

a grounding clip

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

Supplemental grounding electrodes must meet the following requirements

Withstand and dissipate repeated surge currents, Provide corrosion resistance to various soil chemistries, Be rugged enough to drive into the soil with minimal effort and damage

What is a short circuit?

a conducting connection, whether intentional or accidental, between any of the conductors of an electrical system, whether it is from line-to-line or line-to-ground

what is a short circuit?

a conducting connection, whether intentional or accidental, between any of the conductors of an electrical system, whether it is from line-to-line or line-to-ground

What does an effective ground-fault path provide?

a permanent, continuous path to safely conduct fault current, and has low enough impedance to limit the voltage to ground and facilitate the operation of circuit protective devices

A separate derived system is?

a premises wiring system whose power is derived from the source of electrical energy other than a service

In a three-point test to measure the resistances of a grounding electrode with most ground testers

an auxiliary current electrode and an auxiliary potential electrode are required

What is a ground fault

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

what is a ground fault?

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

where can the system bonding jumper be installed?

at the generator or any point in between

The maximum value of fault current depends on the?

available capacity the system can deliver to the point of fault

The continuity between service equipment and enclosures is maintained by

bonding

NEC Article 250

covers the requirements for grounding

A complete resistance curve should be plotted for

each season of the year

How can you determine if a generator is a separately derived system,

examine the transfer switch

AC systems over 1,000 volts must be?

grounded if supplying mobile/portable equipment

Certain systems operating at less than 50 volts require?

grounding

what makes ground to earth connections

grounding electrodes, ground grids, and ground mats

An equipment bonding jumper may be installed either....

inside or outside of a raceway or enclosure

Wire-type grounding electrode conductors may be spliced at any location by means of?

irreversible compression fittings or exothermic welding

Flexible metal conduit can be used as an equipment ground if....

it meets the NEC® installation requirements

Liquidtight flexible metal conduit can also be used as an equipment ground if....

it meets the NEC® installation requirements

grounded electrode conductor

item E in figure RQ01 represents the?

why are circuits grounded?

limit the voltage to ground on the circuit and ensure the stability and continuity of the electrical system

An earth ground resistance tester is used to?

measure soil resistivity and the resistance of the installed grounding electrode system

If a non metallic box is used with a type NM cable

no connection to the box is required

Equipment grounding conductors connect the

noncurrent-carrying metal parts of equipment, conduit, boxes, or enclosures to the system grounded conductor, the grounding electrode conductor, or both

What does a grounding system do?

protects life and equipment against electrical faults

Exothermic welding may only be performed by?

qualified individuals

Ground testers may only be used by

qualified personnel

Other types of electrodes include?

rod and pipe, plate electrodes, and other local metal underground systems such as water piping

If the neutral is not needed for voltage requirements, it still must be?

run to the service and connect to the grounded electrode conductor and equipment grounding conductor at the service

A grounding clip or other device is used to?

secure the equipment grounding conductor to each receptacle to ensure continuity of the grounding system

If the neutral and all phase conductors in the generator are switched, the transformer is?

separately derived

A poorly grounded system can result in?

serious injury or death due to hazardous step and touch voltages

There are two categories of grounding. what are they?

system grounding and equipment grounding

NEC 250, part x discusses the grounding requirements for?

systems over 1kV

Subsequent measurements need only be made at?

the 62% point and 10 feet (3 meters) on each side

A common grounding electrode conductor is required to ground both?

the circuit grounded conductor and the equipment grounding conductor

The equipment grounding conductor (EGC) is....

the conductor used to interconnect and bond the noncurrent-carrying metal parts of equipment, raceways, and other enclosures to the system grounded conductor and/or the grounding electrode conductor at the service equipment or the source of a separately derived system

When installing grounding at more than one building what must be done with the GCC and EGC?

the grounding circuit conductor and equipment grounding conductor must both be extended to the second building

Equipment bonding jumpers has to be sized for?

the overcurrent device

System grounding relates to

the service-entrance equipment and its bonded components

The main bonding jumper must be rated for

the size of the service conductors

The size of the grounding electrode conductors depends on?

the size of the service entrance

If the neutral and all phase conductors are switched

the system is separately derived

If the neutral and all phase conductors are switched what is the transformer?

the transformer is separately derived

The grounded conductor or neutral permits

utilization of power at line-to-neutral voltage and provides a low-impedance return path for the flow of fault current

The fall-of-potential method measures the?

voltage drop between the grounding electrode and an auxiliary potential electrode

Incorrect readings may be obtained

where there are natural soil currents caused by electrolytic action, or induced currents in the soil, instrument, or electrical leads