Installation Guide

1. Install one 4/0 AWG down conductor from the MGB bar on the roof to a MGB bar in the
basement.
2. Bond the basement MGB ground bar to ground by two separate paths.
3. Install two 4/0 AWG conductors from the MGB bar in the basement and terminate each
conductor to one of the following grounding options which are listed in the order of
preference.
Two different options must be selected for bonding the MGB bar to ground:
–
Ground rod or chemical ground rod,
–
Building grounding electrode system,
–
Building steel (if available)
–
Building cold water pipe main entrance.
If the Itron TCU / CCU equipment is located on the ground floor or in the basement, the
MGB may be connected directly to the two selected ground points without using a
second ground bar.
Down Conductor Installation
Each down conductor must consist of 4/0 AWG stranded copper with green insulation.
Preferably, install the down conductor without conduit. If a conduit is required by local standards
or by the landlord, then a non-metallic PVC conduit is preferred. If a metallic conduit is required,
use the threaded type and install grounding bushings on both ends to bond the conduit with a
minimum of No. 2 AWG stranded copper conductor to the ground bar at each end. The metallic
conduit must be bonded at both ends to a ground bar to prevent a choke effect in the event of a
surge.
A low halogen cable that meets the ratings of Telcordia GR-347 is acceptable. Place the MGB
bar as close as possible to the equipment cabinets and the path to ground options (for example,
ground rod, cold water pipe, or building steel). Install the ground bar to ensure that the wire
bending radii for the 4/0 AWG and No. 2 AWG are a minimum of 12 inches and that all paths to
ground travel flat or down.
Warning! Never allow a path to ground to travel upward.
Cold Water Pipe Option
The location of the cold water main is usually in the basement or in the mechanical room of the
building. When attaching to the pipe, the clamp must come into contact with a minimum of 4
linear inches of pipe or utilize a Burndy GAR clamp.
23 June 2020 TDC-0971-012 Itron, Inc. Page 123 of 134
CCU 100 and Repeater 100 Installation Guide F Grounding Specifications