Impedance characteristics of grounding electrodes on earth surface

This paper deals with the comparison of impedance characteristics of grounding electrodes on earth surface and those that are buried underground. The impedance characteristics are investigated analytically, experimentally and numerically. It has been found that there exists no significant difference of a transient resistance between a grounding electrode on the earth surface and a conventional buried electrode, when the electrode length is greater than some 10 m. The result agrees with that evaluated by well-known Sunde's formula for a steady-state resistance of a grounding electrode. The observation suggests that a grounding electrode does not necessarily need to be buried at a large depth, but can be laid on the earth surface covered by soils in a place where the touch and step voltages are not significant.

► Steady-state/transient resistances of an earth-surface electrode.
► Comparison of the resistances with a conventional buried electrode.
► Investigation by experiments, theoretical analysis and FDTD simulations.
► Possibility of saving the construction cost by the earth-surface electrode.