Practical impact of measured seasonal variations in soil resistivity

When designing earthing systems, soil resistivity is one of the key drivers of decisive parameter like earth potential rise and touch voltage. The resistivity of soil depends on many factors, including moisture and temperature of the soil. Seasonal variations of moisture and temperature lead to variations of these parameters. Due to this fact the selected time to perform the measurement of soil resistivity may influence the results of calculating earth resistances, earth impedances or touch voltages strongly. This paper will summarize some of the most important findings of an Online-Monitoring-System of a soil resistivity measurement and describe practical impacts derived from it.