Resistance Calculations Sample Clauses

Resistance Calculations. When computing resistance to ground, treat the tower grounding and the shelter grounding as two separate systems. Within each of these two systems are two subsystems. The shelter has a grounding ring and the grounding rods. The tower has a grounding ring, grounding rods, and occasionally, grounding radials. The IEEE Green Book provides several formulas for calculating the resistance to ground for several different systems. 4. Typical Grounding Configurations Several options are available when deciding on a ground system for a communication shelter, depending upon the soil conditions and thunderstorm activity of a particular site. The U.S. Weather Bureau publishes an isoplethic map of the United States showing the average number of days each year on which thunderstorms occur. Any area with an isoplethic level above 90 should be considered a high-risk area, and serious consideration should be given to providing a more stringent grounding system.