Transient analysis of grounding systems without computer

Recently simple empirical formulas have been introduced that estimate the impulse impedance, impulse coefficient and effective length/area of different arrangements of grounding electrodes (horizontal and vertical electrodes and grounding grids) under typical lightning currents. Soil ionization and inductive effects are both included in the formulas for smaller simple arrangements of grounding electrodes, while soil ionization is ignored for grounding grids. To illustrate and validate the new formulas, we compare the results from the formulas with experimental data recently published by different research groups.