16
IC System
TM
Design Guide, v2.3
Grounding
Proper grounding is very important for the IC system
TM
. The system grounding is accomplished through
the ICSD surge devices that are installed on the wire path. Rain Bird MSP surge devices are installed on
each wire path prior to entering the Integrated Control Interface (ICI) at the central.
Important!
An Integrated Control Surge Device “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
th
station) as a normal design practice.
The purpose of field surge devices is to offer “containment” of surge during an event so that damage
caused by the event will be limited by an ICSD located on either side of the event. The key for successful
containment is proper installation of ground rods or plates so that the desired Ohms resistance level is
achieved.
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 run of 2,000 feet (609 meters) between ICMs, an ISCD should be
installed immediately after the last ICM and just prior to the next ICM. ICSDs are not required at 500
foot (150 meter) intervals on the 2,000 foot (609 meter) run of wire.
At the ICI, for a long run (greater than 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
The IC System must have grounding throughout the wire path to allow any transient surges the
opportunity to leave 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) from the next ICSD.
2.
Each ICSD can be located either next to a valve-in-head rotor or in-line valve. The ICSD should
be accessible in case of maintenance. Either a ground rod or plate can be utilized to obtain an
earth ground reading of 50 ohms or less.
3.
The grounding requirement at the central control is to have less than 10 ohms of earth ground
resistance. 5 ohms or less of ground resistance is preferable. The central control shall utilize