Grounding Requirements - Field Locations - Rain Bird IC System Design Manual

500 feet or 150 meters) at the beginning of the wire path, the MSP should be installed at the interface
and an ICSD installed just prior to the first ICM on the wire path.
Grounding Requirements – Field Locations
The purpose of field surge devices is to "contain" and drain surge energy during an event, so that any
damage caused by the surge will be limited by an ICSD located on either side of the event. Successful
containment is dependent upon proper ICSD location and effective grounding where the desired Ohms
resistance level is achieved.
An ICSD should be located every 15 ICMs or every 500 feet (150 meters), whichever condition is reached
first. This is a guideline for design purposes and designers should try to stay as close to these guidelines
as possible. However, in the example of a herringbone system with 4 stations per pipe lateral, an ICSD
could be installed every fourth lateral (therefore every 16
Important! During long runs of wire where there are no ICMs, an ICSD is not required every 500
feet (150 meters).
For example, if there is a wire length of 2,000 feet (609 meters) between ICMs on a wire path, one ISCD
should be installed immediately after the last ICM prior to the empty length and one just prior to the next
ICM. ICSDs are not required at 500-foot (150 meter) intervals on the intermediate 2,000 foot (609 meter)
run of wire.
The IC System must have grounding throughout the wire path to give transient surges the opportunity to
exit the wire path. The following requirements must be followed to properly ground the IC System:
1. Each ICSD must have an earth ground resistance of less than 50 ohms and be no more than 500
feet (150 meters) or 15 ICMs from the next ICSD.
2. ICSDs can be located either next to a valve-in-head rotor or in-line valve, whenever possible ICSDs
should be installed in a valve box. The ICSD must be accessible for maintenance. A ground rod,
plate, or any combination of the two should be used to reach an earth ground reading of 50 ohms
or less.
3. The primary objective of grounding is to achieve the desired earth ground reading for the rods or
plates regardless of which method is used. Rain Bird has had good success with ground rods when
soil conditions allow them to be driven completely into the soil profile. An 8-foot (2.4 m) rod will
help distribute a surge into lower layers of the soil profile, away from the soil surface and
equipment. If required, rods can be coupled together; or a second rod outside the sphere of
influence of the first rod may be successful.
4. ICSDs should be located at dead ends on long wire runs, approaching 500 feet (150m.) Short wire
runs do not require ICSDs at dead ends. Herringbone pipe layouts do not require ICSDs at the end
of each herringbone lateral.
IC System Design Guide, v2.4
th station) as a normal design practice.
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