Earthing is paramount to the design of new infrastructure, both in order to keep people safe by preventing electric shocks and in avoiding damage from overloading caused by excess currents running through the circuit.
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The planning and installation of new generators, substations, solar & wind farms and the associated electrical grid infrastructure requires full understanding of a site’s electrical properties for the design of an appropriate earthing system that may include earthing plates, earthing rods, or earthing pits, depending upon the exact requirements and site conditions.
If not earthed correctly, solar panels and other electrical equipment can be damaged by electrical surges, lightning strikes, and other electrical disturbances. The damage can reduce the efficiency of the solar panels and wind turbines, and even cause them to fail, leading to costly repairs or replacements.
Soil Resistivity Testing
Soil resistivity measures the capacity of the ground to pass an electrical current and is a critical factor in the planning and installation of an electrical earth, with soil layer models forming the basis of all grounding designs. The models are produced from accurate soil resistivity testing carried out on site at the predevelopment stage.
Above : Soil resistivity testing in progress on a new solar farm development.
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A series of depth readings are acquired using different electrode spacings, allowing the apparent resistivity of the ground to be recorded at regular depths to 50m or more at any given point. The resultant data is presented in tabulated form (below) as well as in graphs, listing the electrode spacing, nominal testing depth; electrical resistance for each electrode spacing (R1, R2); average resistance (Rav) and apparent resistivity for each position. As a general rule, lower resistivities make the design and installation of an earthing system simpler.
Above : Tabulated soil resistivity testing results at standard electrode spacings.
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The resistivity values are also correlated with borehole data from the site to provide the design engineer with an electrical model of the soil and bedrock layering that can also be correlated with borehole data from the site. A typical model below displays a progressive increase in resistivity with depth.
Geophysical Engineering Surveys
Air Raid Shelters
Cellars & Basements
Post Tension Cables
Underground Storage Tanks
Air Voids
Chimney Flues
Rebar
Water Engineering
Badger Setts
Earthing Installations
Sinkholes
Burials
Geological Application
Soil Thermal Resistivity Testing
Buried Foundations
Landfills
Structural Investigations
Buried Manholes
Mineshafts
