S1400T-2808B Page 3-2 Section 3 - Grounding & Isolation
Electrical Housing) and a known good Earth Ground. Observe recommendations provided
in topics Establishing a Good Earth Ground
and Ground Wire Considerations.
3.3.1 Establishing a Good Earth Ground
A common misconception of a ground is that it consists of nothing more than a metal pipe
driven into the soil. While such a ground may function for some applications, it will often
not be suitable for a complex system of sophisticated electronic equipment. Conditions such
as soil type, composition and moisture will all have a bearing on ground reliability.
A basic ground consists of a 3/4-inch diameter rod with a minimum 8-foot length driven into
conductive earth to a depth of about 7-feet as shown in Figure 3-1. Number 4 AWG solid
copper wire should be used for the ground wire. The end of the wire should be clean, free of
any coating and fastened to the rod with a clamp. This ground connection should be covered
or coated to protect it from the weather and the environment.
Figure 3-1 - Basic Ground Rod Installation
3.3.1.1 Soil Conditions
Before installing a ground rod, the soil type and moisture content should be analyzed.
Ideally, the soil should be moist and moderately packed throughout to the depth of the
ground rod. However, some soils will exhibit less than ideal conditions and will require
extra attention.
Soil types can be placed into two general categories with respect to establishing and
maintaining a good earth ground, i.e., ‘Good Soil’ and ‘Poor Soil.’
To be a good conductor, soil must contain some moisture and free ions (from salts in the
soil). In very rainy areas, the salts may be washed out of the soil. In very sandy or arid area
To Next Page
Loading...
