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FieldSmart
®
Fiber Active Cabinet (FAC) 3200
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Installation Manual
Direct: 763.476.6866 • National: 800.422.2537 • www.SeeClearfield.com • [email protected]
Manual 020421 REV A - Jan 2019
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
complex system of buried rods and wires. The lower the resistance of the electrode-to-earth connection, the more effective
the ground system is 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
practical. If 5 ohms or less cannot be achieved, the maximum ground impedance should meet local codes or the NEC
requirement 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 ground via an earth ground wire (2 AWG solid bare copper) bonded to the ground rod and buried at
the site. Multiple inter-connected ground rods provide increased ground electrode-to-earth conductivity. You can add
supplemental ground rods to a single ground electrode 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 rods that encircle the perimeter of a site.
Ground rings represent
the preferred earth grounding system for cabinet deployments
. Ground rings follow the provisions for multiple ground
rods, with an additional NEC provision that the ground rings should consist of at least 20 feet of bare copper conductor
not smaller than 2 AWG.