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Earth DC resistance (typically ‹10 ohms) and impedance (typically ‹30 ohms) is required for
successful operation of LPI Guardian System 5.
LPI recommends the installation of a radial lightning earth as shown in figure 9.
• Recommended to install a 3 x 10 metre length radial trench.
• Each radial should consist of a trench (Approx: 500mm Deep x 200mm wide x 10m length).
• An earth rod should be driven at the end of each trench.
• All rods should be interconnected through the use of 25mm x 3mm copper tape. The use of
earth rod clamps to fix the tape to rods is recommended.
• Use waterproofing mastic on all mechanical connections.
• The application of earth enhancing compounds such as LPI RESLO and GRIP assists to
reduce soil resistivity to the recommended level of less than 10 ohms.
• An earth pit should be installed where the end of the downconductor terminates to the
lightning earth as shown in figure 9. This gives an access point for disconnection
and future testing.
• Do not lower terminate (connect) the downconductor to the earthing system at this point in
time.
Note: If due to space constraints it is not possible to install a radial earth as recommended,
consult with LPI or an authorised distributor for further advice.
When using earth rods:
• Use driving heads to prevent mushrooming on top of rod.
• Use driving heads when using coupled rods.
• Use a post or picket driver.
Recommendations for bonding the earthing system components are listed below:
• The use of the EXOWELD exothermic welding process is a safe and efficient way of
providing a permanent connection between conductors. EXOWELD connections will not
corrode or rust with age.
• DO NOT use aluminium lugs or couplings.
14
Guardian Install Manual V12.indd 16
Document 36 II Guardian
Version 1.02
© Copyright 2008 LPI
22/9/08 4:25:23 PM
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