16
WS-PRO LT weather station
Appendix
A
–
Grounding
Recommendations
A.1
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.
A.1.1
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
A.1
‐
1
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
should
have
a
dedicated
irrigation
zone
with
sprinkler
heads
and
its
own
watering
program
to
maintain
soil
moisture
around
the
grounding
system.
A
properly
installed
grounding
system
should
maintain
a
maximum
ground
resistance
of
10
ohms,
or
less.
If
you
are
unable
to
reach
a
resistance
of
10
ohms
or
less,
you
can
decrease
resistance
by
surrounding
the
grounding
rods
or
plates
with
ground
enhancement
material,
such
as
POWER
SET
from
Paige
Electric
Corporation
(P/N
1820058),
or
GEM
from
ERICO
(P/N
GEM
‐
25A).
If
ground
resistance
still
measures
higher
than
10
ohms,
you
can
extend
the
ground
rod
length
as
described
in
“Ground
Rod
Stacking,”
or
use
additional
grounding
rods,
as
shown
in
grounding
system
design
“Y”
(Alternate).
A.1.2
Installation
Requirement
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
eight
inches
and
a
minimum
included
angle
of
90
o
.
