Nothing is so common or abundantly available around the world
like the earth from the ground. We are more inclined to see the earth as something to be
cultivated for planting or to be excavated for a foundation of a building. But it also has an electrical property - conductivity (or low resistance) - that is used practically every day in industrial installations and utilities.
Broadly speaking, "earth resistance" is the resistance of the soil to the earth
passage of electric current. The earth is actually relatively poor
conductor of electricity compared to normal conductors such as copper
wire. But if the area of a path for current is large enough, resist
can be quite low and the ground can be a good conductor. From the earth there is
abundance and availability making it an indispensable part of one
properly functioning electrical system.
Earth resistance is measured in two ways for two main application areas:
It is not the intention of this guide to go too deeply into the theory as well
math of the subject. As noted in the references at the end,
there are many excellent books and newspapers covering these. On the contrary, the
the information herein is in simple language so that it can be readily
understood by the user in the industry.