Application Note

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Application Note

From the Fluke Digital Library @ www.fluke.com/library

Maintaining a solid ground

Why must a facility

electrical system have a

good electrical ground?

In addition to being required

by the National Fire Protec-

tion Association (NFPA) and

the Occupational Safety Health

Administration (OSHA), and

recommended by the Institute of

Electrical and Electronics Engi-

neers (IEEE), American National

Standards Institute (ANSI),

and the International Electro-

technical Commission (IEC), a

well-grounded system increases

electrical safety and decreases

the odds of equipment damage

or failure.

The National Electrical Code

(NEC) provides specific require-

ments for both utility-provided

electrical service and separately

derived systems. A separately

derived system receives power

from a source of electrical

energy or equipment other

than the utility service. Here

we’ll address certain aspects

associated only with ground-

ing utility-provided electrical

service.

The Fluke 1621 Earth Ground Tester is an easy-to-use earth ground tester,

the first line of defense in detecting reliable ground connections.

Definition of terms

Article 100 of the NEC includes

definition of terms essential to

the proper application of the

code. The following electrical

system grounding definitions are

from Part I of Article 100:

• Ground: The earth.

• Grounded: Connected to

ground or to a conductive

body that extends the ground

connection.

• Grounded conductor: A

system or circuit conductor

that is intentionally grounded.

• Equipment grounding con-

ductor: The conductive path

(or paths) installed to connect

normally non-current-carrying

metal parts of equipment

together and to the system

grounded conductor or to the

grounding electrode conduc-

tor, or both. It is recognized

that the equipment ground-

ing conductor also performs

bonding.

• Grounding electrode: A con-

ducting object through which

a direct connection to earth is

established.

• Grounding electrode con-

ductor: 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.

Summary of content (2 pages)

PAGE 1
Maintaining a solid ground Application Note Why must a facility electrical system have a good electrical ground? In addition to being required by the National Fire Protection Association (NFPA) and the Occupational Safety Health Administration (OSHA), and recommended by the Institute of Electrical and Electronics Engineers (IEEE), American National Standards Institute (ANSI), and the International Electrotechnical Commission (IEC), a well-grounded system increases electrical safety and decreases the odds
PAGE 2
Grounding connections A premises wiring system supplied by a grounded ac service must have a grounding electrode conductor connected to the grounding service conductor. The connection must be made at an accessible point from the load end of the service drop or service lateral to the terminal or bus to which the grounded service conductor is connected at the service disconnect. Service drop refers to overhead conductors; service lateral refers to underground conductors.