User's Manual

Appendix F Grounding Specifications
100 TDC-0971-011 CCU 100 and Repeater 100 Installation Guide
Proprietary and Confidential
2. Request a copy of any soil resistivity and/or site resistance to earth testing previously
performed on the proposed site.
Note: A clamp-on ground resistance test may be performed at existing building sites
where it isn’t feasible to perform a site resistance to earth test. Refer to Clamp-On
Ground Resistance Testing on page 117
for the proper testing procedure.
Co-Located Sites & Other Existing Structures
Review all co-located sites to determine if an existing qualified ground system is present
based on a copy of any soil resistivity and/or site resistance to earth testing previously
performed on the proposed site.
If no prior soil resistivity records are available and there is land space available, a soil
resistivity test is suggested.
New Wood Pole Sites
Test all proposed site locations before completing external ground ring design. It is the
contractor’s responsibility to advise Itron of the resistivity of the site by submitting the
required forms before any construction of the BGR can be started by the contractor.
Equipment Buried Ground Ring
The following is a list of required specifications for all Itron sites not installed on a lite
pole structure. This includes TCU, CCU, and Repeater sites:
• All sites must have a BGR around the equipment pad or platform. The BGR is to
consist of a ring of No. 2 AWG BTCW and exothermically welded ground rods.
The BGR design is site specific. The design should result in 5 ohms or less with soil
resistivities of up to 50,000 ohm-cm. Soil resistivities higher than this require further
augmentation that is beyond the scope of this practice and should be designed
specifically for the site by a qualified engineer.
• All underground (below grade) grounding connections, including copper ground rods,
chemical ground rod attachments, and ground leads from equipment, tower, and coax
must be made by an exothermic weld.
• The ground ring between 18" and two feet from the BTS pad or platform perimeter at
a minimum depth of two feet, six inches (or deeper depending on frost line), and with
no bend having a radius of less than two feet.
• A 6-inch trench dug below the required wire depth.
• Ground rods installed, at a minimum, at each corner of the BGR.
• Minimum ground rod length must be either (1) 10’-0" or (2) site frost depth plus 10’-
0" minus the depth of the ground ring, whichever is greater.
Example 1. Site frost depth = 4’-0" and the ground ring is installed at 2’-6" below
final grade. Minimum ground rod length would be 11’-6" (4+10-2.5).
Example 2. Site frost depth = 1’-6" and local codes require the ground ring to be
installed minimum 2’-6" below grade. Minimum ground rod length = 10’-0" since it
is greater than 9’-0" (1.5+10-2.5).