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© 2001-2008 Calix. All Rights Reserved.
Installing a Ground Circuit
Calix 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 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. Calix 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.
