Soil electrical resistivity testing (SERT) shows up across a wider range of Australian infrastructure work than many people expect. While it’s best known for earthing design, the same underlying measurement — how strongly soil resists electrical current — feeds into decisions across energy, pipeline and geotechnical projects nationally.
What SERT Involves
Testing is typically carried out using a four-point (Wenner) method, where electrodes are driven into the ground at set spacings to measure resistivity at different depths without disturbing the soil. This gives a depth profile of how resistivity changes beneath the site, rather than a single surface reading.
Where It’s Used
- Substations and switchyards — sizing earth grids to safely dissipate fault current.
- Solar and wind farms — earthing inverter stations and switchyards, and informing cable route thermal design across the site.
- Pipelines — resistivity directly affects corrosion rates on buried steel pipelines, feeding into cathodic protection system design.
- Geotechnical investigations — resistivity profiling can help identify subsurface layering and groundwater presence ahead of more detailed site investigation.
Why Australia’s Soils Make This Non-Negotiable
Few countries span the range of soil conditions Australia does within single states, let alone nationally — conductive coastal sands, cracking inland clays, rocky ranges and deeply weathered tropical soils can all sit within one project’s footprint. A resistivity figure that holds true in one location can be meaningless a short distance away, which is exactly why testing is done at the specific site rather than assumed from regional soil maps.
Getting Defensible Results
Whatever the application, the value of SERT comes down to how it’s tested and reported: at the right depths, across enough of the site to capture real variation, and referenced against the standards the next stage of design will rely on. Our soil thermal & electrical resistivity testing service covers all of the above, for projects of any size, Australia-wide.