Rain Bird PAR+ES Installation Manual - Appendix
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Appendix
Controller Grounding System Installation
To prevent lightning damage to your equipment,
Rain Bird recommends installing a grounding system
for the equipment (including controllers, weather
stations, and central control systems)
The grounding system discharges lightning-induced
electrical current into the earth rather than allow the
surge to pass through power wires or field wires to
your equipment’s electronic components
Ground Resistance
Ground resistance occurs when grounding system
components, or the soil itself, oppose the flow
of electricity into the earth Ground resistance is
measured in units called “ohms” (Ω)
The higher the ground resistance (higher ohm
readings), the less chance the surge will be shunted
to ground rather than to the equipment’s electronic
components
Figure 18 shows points where grounding systems can
develop resistance
To decrease ground resistance, Rain Bird recommends
irrigating the soil around the grounding system
Each grounding system may require a dedicated
irrigation zone with sprinkler heads and its own
watering program to maintain soil moisture around
the grounding system
A good grounding system should maintain a ground
with a resistance of 10 ohms or less Anything 15 ohms
or greater offers little protection to the controller’s
electronic circuits
If you are unable to reach a resistance of 10 ohms
or less, you can enhance the ground network with
additional ground electrodes or plates
Installation Requirements
The following requirements apply to all grounding
system designs (design “Y” and the “Grounding Plate”
design)
All grounding rods or plates must be connected
together below grade with #6 AWG or larger solid
bare copper wire
Install the connecting wire in as straight a line as
possible If you must make a turn or bend in the wire,
make the turn in a sweeping curve with a minimum
radius of 8” and a minimum included angle of 90°
To minimize resistance, the copper wire must be
pre-welded to the grounding rods/plates, or welded
to the rods/plates using an exothermic welding
process at the site
Make sure all welds are secure before burying the
grounding rods Rods and plates with welded joints
do not need periodic visual inspection and can be
fully buried (no valve box required)
Measure the ground resistance around the grounding
system after installation, and once every year after
that
NOTE:
!
The ground wire from the equipment
to the grounding system should be as short
as possible and have no bends, kinks, or coils
in the wire
Inspect the grounding system’s clamped connections
to the equipment (not the welded grounding system
connections) once a year to make sure they are secure
and corrosion-free
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