Installation Guide

A low impedance ground is imperative to both surge protection designs and power quality.
Regularly inspecting and upgrading the system can positively affect the system in the following
ways:
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reduce interference and line noise
■
reduce the risk of accidental electrocution
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decrease potentially damaging harmonics
■
improve power factors
■
improve the efficiency and durability of the surge protection equipment
Understanding Grounding and Bonding
You must have a complete grounding and bonding system between the electrical service
entrance and remotely grounded buildings or equipment. If the remote ground home runs back
to the service entrance, create a single point ground that references the initial utility company
electrical ground back at the service entrance electrical meter.
In this document, the definition of grounding and bonding is as follows:
■
Ground/Grounding. Any direct conducting connection between an electrical circuit or
equipment and earth.
■
Bond/Bonding. The permanent connection of metallic parts to form an electrically
conductive path. For example, an electrical service panel that is grounded while the
telecommunications rack is bonded to the grounding system.
Understanding the Ohms Level
According to articles 100 and 250 of the NATIONAL ELECTRIC CODE (NEC) an acceptable
ground is rated at 25 Ohms of resistance or less, but optimum performance of surge protectors is
achieved at 5 Ohms or less. Several manufacturers of electronic equipment also require 5 to 10
Ohms as a maximum resistance for their gear to work correctly.
Reducing the Ohms level
In many areas of the country you may be starting with 350 Ohms or more. Itron’s networks are
built all over the United States and the geological features can vary greatly in different parts of
the country; therefore, allow the installing contractor to determine how best to lower resistance
to ground (to 5 Ohms or less) in a specific region. The recommended grounding conductor at the
service entrance is specified by NEC based on the ampacity of the service.
You can perform the following tasks to reduce the Ohms level:
■
Measure the resistance to ground at the service entrance meter’s electrical ground, or of the
soil itself. Soil resistance can be affected by the following:
CCU100 and Repeater100 Installation Guide F Grounding Specifications
12 February 2021 815-0491-00 Itron, Inc. Page 104 of 133