New method for measuring the electrical resistivity of a thin layer of earth

In order to maintain an adequate safety level in a substation, resistivity of the surface layer must be estimated in situ and during a sufficiently long period of time to take into account the various effects of the climatic conditions. The purpose of the surface layer is to keep the exposure to touch and step voltages to a safe value for a person standing inside or near a substation yard. Conventional techniques are not suitable to achieve resistivity measurements especially for a thin layer of soil. In view of this, a new two-point technique has been proposed which allows semi-continuous measurement of the resistivity of a specific volume of soil. Results have been shown to demonstrate the effect of climatic conditions over the resistivity of a thin surface layer