FieldSmart
®
FiberFlex 2000
Installation Manual
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Proprietary Information: Not for use or disclosure except by written agreement with Clearfield.
22
Installing a Ground Circuit
Clearfield requires installing an earth ground circuit (earth electrode) at the installation site to provide protection from electric
shock for equipment and personnel. The ground circuit may consist of a simple copper rod driven into the earth or a com-
plex system of buried rods and wires. The lower the resistance of the electrode-to-earth connection, the more effective the
ground system for safety and lightning protection.
Proper grounding conditions and requirements vary per site. The National Electric Code (NEC) specifies a maximum ground
impedance of 25 ohms. Clearfield recommends achieving a ground impedance of no greater than 5 ohms wherever prac
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tical. If 5 ohms or less cannot be achieved, the maximum ground impedance should meet local codes or the NEC require
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ment of 25 ohms, whichever is less.
Grounding options
The cabinet main ground system must be bonded to a suitable earth ground circuit, which may include any of the following:
• Ground rod(s):
A ground rod consists of a simple copper rod driven into the earth. A ground rod connects to the main
cabinet or enclosure ground via an earth ground wire bonded to the ground rod and buried at the site. Multiple inter-con-
nected ground rods provide increased ground electrode-to-earth conductivity (ground grid). You can add supplemental
ground rods to a single ground grid in several arrangements, including a linear chain, fan array, or ring configuration.
Refer to the NEC or local regulations for restrictions and details. All bonds to grounding electrodes must be suitable for
direct burial using irreversible mechanical connections or exothermic welds. Follow local code or site practice to satisfy
any additional grounding requirements.
• Ground ring:
A ground ring consists of multiple ground electrodes that encircle the perimeter of a site. Ground rings
represent the preferred earth grounding system for cabinet deployments. Ground rings follow the NEC provisions for
multiple ground electrodes.
