ERICO Practical Guide to Electrical Grounding - Manual (Page 6)

Practical Guide to Electrical Grounding
essential to provide a reference function. Another suitable
conductive body may be used instead.
The function of a grounding electrode system and a ground
terminal is to provide a system of conductors which ensures
electrical contact with the earth. Two Fine Print Notes
(FPN) that appear in Section 250-1 of the NEC provide a
good summary of the reasons for grounding systems and
circuit conductors and the conductive materials which
enclose electrical conductors and equipment.
TYPES OF GROUNDING
As noted above, grounding and bonding are not the same.
In addition, not all grounding is the same. Each chapter or
section in this book will describe one or more of the various
types of grounding and bonding that are widely used in the
electrical industry. Topics of primary interest are:
• Power System Grounding Including
The “Service Entrance”
• Bonding
• Grounding Electrical Equipment
• Lightning Protection
• Protection Of Electronic Equipment
(Shielding Is Not Discussed)
Grounding is a very complex subject. The proper instal-
lation of grounding systems requires knowledge of soil
characteristics, grounding conductor materials and
compositions and grounding connections and terminations.
A complete guide to proper grounding is often part of
national and international standards. For example, IEEE
Std 80, Guide for Safety in AC Substation Grounding, is a
comprehensive and complex standard for only one
particular grounding application. This standard is needed
for proper substation design in an electric power
transmission facility or the power feed to a very large
factory. Smaller facilities can use these design guides also,
but such an approach may be too costly. This book takes
“conservative” shortcuts that allow the design of the
grounding system to proceed without undue design effort.
We emphasize that the approaches in this book, in order
to be conservative and correct, may trade a small increase
in grounding components in order to avoid a large
engineering expense. Remember that any electrical instal-
lation is, and properly should be, subject to a review by the
authority having jurisdiction over the electrical installation.
Electrical design and installation personnel are encouraged
to discuss and review the electrical installation with the
authority having jurisdiction PRIOR to beginning any work
on the project.
Designers of electrical grounding systems also should find
this a handy guide because we have included extensive
references to the National Electrical Code (NEC)
(NFPA70), ANSI and IEEE Standards as well as other
NFPA Standards. It is not the purpose to be a guide to the
NEC but we will not make recommendations that disagree
with it. Keep in mind that Section 90-1 (c) of the NEC
states that the Code is not intended to be used as a design
specification. Still, it is difficult to imagine how personnel
design and construct electrical systems in the USA without
referencing the NEC. Also keep in mind that the NEC
contains minimum requirements only. In some cases,
minimum standards are not sufficient or efficient for the
design project. For example, existing standards do not cover
the need to maintain the operational reliability of modern
electronic equipment - especially telecommunications and
information technology (computer-based) systems. We will
cover these situations in this book. Where no standards
exist, the ERICO engineering staff can make recommen-
dations based on more than 58 years of successful
experience.
While written primarily for readers in the U.S. and Canada,
readers from other nations also will find this work useful
because it concentrates on cost-effective, proven solutions.
This book is written around U.S. standards with references
to Canadian Standards. The standards in your country may
be different. We welcome your comments. ERICO operates
in 23 countries around the globe. We are familiar with most
commonly referred standards. If you contact us, we will try
to assist you in any way.
A fundamental fact is that electricity ALWAYS flows back
to its source. Some designers and installers who accept and
use this fact in their designs of power systems, seem to
forget it when designing and installing grounding systems.
Our job is to ensure that electricity, including faults,
lightning and electronic noise, return to their source with a
maximum of safety to people while maintaining the
reliability of equipment. This means that we must be sure to
route the current back to its source with a minimum voltage
drop. In many individual situations there are no specific
NEC requirements to accomplish this so we will let theory
and experience be our guide.
ERICO is publishing this book as a service to our
customers and other industry professionals who realize that
grounding, bonding, lightning protection and overvoltage
protection are an integral part of a modern electrical design.
We have referenced many of our products in the midst of a
comprehensive technical paper. We acknowledge that there
are other good products one could use. ERICO’s 70 plus
years of experience in designing and manufacturing
bonding and grounding products has led us to what we feel
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