Electrical Level 2 Module 9 Grounding and Bonding

Plate electrodes must have at least ___ feet of service area exposed to the surrounding Earth.

2 square

A ground ring consisting of 20' of #2 bare copper must be buried no less than ____ feet below grade.

2.5

Rod, pipe, and plate electrodes must have a resistance to ground of at most

25 ohms or less.

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

3/4 of 1 inch.

The minimum length allowed for driven ground rods under normal conditions is ___ feet

8

Grounding Electrode:

A conduction 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 grounded 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.

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.

A ground fault is

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 grounded circuit conductor, to supply conductors originating in another system.

Grounded Conductor:

A system or circuit conductor that is intentionally grounded.

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, 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.

Grounded:

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

Bonding:

Connecting to establish electrical continuity and conductivity.

Grounding Connections:

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

Ground Current:

Current in the earth or grounding connections.

( or neutral ) is what connects to the neutral terminal bus of a main panel.

Grounding electrode conductor

Auxiliary Electrodes:

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

Grounding requirements for AC SYSTEM are contained in

NEC section 250.20 and 250.21.

Resistivity:

Resistance between opposite faces of a unit cube. Expressed in ohm-centimeters or ohms per cubic centimeter.

Ground Mat:

System of bare conductors on or below the surface of the earth connected to a ground or ground grid to provide protection from dangerous touch voltage.

Ground Grid:

System of grounding electrodes interconnected by bare cables buried in the earth to provide lower resistance than a single grounding electrode.

Equipment grounding Conductor (EGC):

The conductive path(s) that provides a ground-fault current path and connects normally non-current-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.

Ground:

The earth or a conducting connection to the earth,

Ground Resistance:

The ohmic resistance between a grounding electrode and a remote or reference grounding electrode that are spaced such that their mutual resistance is essentially zero.

Step Voltage:

The potential difference between two points on the earth's surface separated by the distance of one pace or almost 3'.

For separately derived systems that are required to be grounded

an equipment grounding conductor must be supplied with the primary circuit.

If the neutral in a grounded system is not needed for voltage, the system must be run to the service

and connected to the grounding electrode conductor (Neutral) and the electrode grounding conductor (Ground).

A short circuit is a conducting connection between

any of the conductors of an electrical system.

Plate electrodes

are made of copper must be at least .06 inches thick.

AC systems over 1000V that supply mobile or portable equipment

are required to be grounded.

The continuity between service equipment and enclosure is maintained by

bonding.

The size of the equipment grounding conductor (EGC)

is determined by the size of the overcurrent device.

The bonding jumper for multiple disconnecting means

is located on the supply side of the service disconnect.

The Neutral in a grounded system provides a

low impedance return path for the flow of fault current to the source.

A separately derived system for a premises wiring system is

powered from a source other than a service entrance.

A grounding test utilizing an earth ground resistance tester known as

the 3-point method.

An acceptable grounding electrode is

the Metal frame of a building which is effectively grounded.

System less than 50V must be grounded if

the supply voltage to the transformer exceeds 150V.

To be effective, a grounding system must limit

the voltage on the electrical system and protect it from a voltage surge.

The maximum value of a short circuit current from line to ground will

vary depending on the distance from the source to the fault.

Ultimately, the ground fault is cleared

when the overcurrent devices are opened.

Short circuit:

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

The requirement for grounding of services are located in

NEC section 250.24(A), (B), (C), and (D).

The equipment grounding conductor would be sized using _____________ based on the overcurrent device supplying the second structure.

NEC table 250.122

The GEC in the second structure is sized using ____________ based on the size of the feeder conductors.

NEC table 250.66

If single-gang nail-on non-metallic boxes are used with NM cable, which of the following is true ?

No connection to the box is required

Touch Voltage:

The potential difference between a grounded metallic structure and a point on the earth's surface equal to the normal maximum horizontal reach- approximately 3'.

Electrical Continuity is the key to successfully

clearing of ground fault currents.

Equipment grounding refers to

connecting the normally non-current-carrying metal parts of equipment to the system grounding conductor and/or the grounding electrode conductor.

In a separately derived system, the equipment bonding jumper

connects the system housing to the neutral bus bar.

Where there is a requirement to add a second grounding electrode, the two electrodes must be separated at

least 6 feet apart.

An earth ground resistance tester may be used to

make soil resistivity measurements or measure the resistance of the installed grounding electrode system to earth.

The path to ground from circuits, equipment and metal enclosures shall be ________________________. This is a requirement for grounding and bonding as stated by the NEC.

permanent and continuous

Grounding Clips are used to

secure Equipment Grounding Conductors (EGCs) to metallic outlet boxes.

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.

Equipment Bonding Jumper:

The connection between 2 or more portions of the equipment grounding conductor.

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.