Section 3 - Grounding & Isolation Page 3-5 S1400T-2808B
Figure 3-5 - Poor Soil Ground Bed Construction Diagram
Sandy soil, either wet or dry, may have had its soluble salts leached out by rain water,
thereby reducing conductivity of the ground. High currents from lightning strikes could also
melt sand and cause glass to form around the ground rod, rendering it ineffective. A buried
counterpoise or copper screen is preferred for these installations along with regular
applications of salt water.
Rocky soil can pose many grounding problems. A counterpoise or copper plate will probably
be required. Constructing a trench at the grounding site and mixing the fill with a
hygroscopic salt such as calcium chloride may help for a time. Soaking the trench with
water on a regular basis will maintain conductivity.
3.3.2 Ground Wire Considerations
i Ground wire size should be AWG 4. It is recommended that stranded copper wire is
used for this application and that the length should be as short as possible.
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