Specialty Materials Testing

Wenner Four-Pin & Soil Electrical Resistivity Testing

Wenner four-pin testing—also called Wenner four-electrode or soil electrical resistivity testing—measures the apparent electrical resistivity of the earth at planned locations and electrode spacings. The field data supports grounding studies, buried-utility corrosion evaluations, substations, renewable-energy facilities, transmission, and cathodic-protection design input.

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Service overview

What this service involves

A Wenner survey uses four electrodes placed in a straight line at equal spacing. The instrument applies current through the outer electrodes and measures voltage between the inner electrodes. The resistance and array geometry are used to calculate apparent soil electrical resistivity for that station and spacing.

Calicore plans the field program around the receiving engineer's objective, site dimensions, desired spacing sequence, anticipated layering, grading, buried metal, overhead conductors, existing grounding, pavement, terrain, utility clearance, and safe access. Programs can include multiple stations, orthogonal lines, repeat readings, long arrays, route surveys, and multi-site mobilizations.

Typical applications include substation and switchyard grounding studies, solar-farm and battery-energy-storage projects, wind facilities, transmission and distribution corridors, data centers, industrial plants, water and wastewater facilities, pipelines, buried utilities, corrosion investigations, and forensic work.

Deliverables can include GPS-referenced stations, array orientation, electrode spacing, raw resistance, calculated apparent resistivity, units, photographs, weather and surface conditions, observed interference, deviations, and engineering discussion. ASTM G57-20 and IEEE 81-2025 are common technical starting points, while the project specification controls the final scope.

Step by step

How the process works

The exact scope is matched to the project, but a typical assignment follows these steps.

01
Define the survey objective
We review the site or alignment, intended grounding or corrosion use, requested locations, spacing sequence, site access, utility clearance, and safety requirements.
02
Lay out the array
Four electrodes are placed in a straight line at equal spacing, with alignment and available geometry documented at each station.
03
Collect repeated readings
Current is introduced through the outer electrodes and voltage is measured between the inner electrodes at planned spacings, locations, and orientations.
04
Calculate and map the results
The deliverable includes measured resistance, apparent resistivity, units, station locations, photographs, site conditions, and noted interferences or deviations.

Review criteria

What the grounding or corrosion designer needs from the survey

The usefulness of Wenner data depends on the test layout and field conditions, not only the final apparent-resistivity value.

Coordinates, alignment, electrode spacing, measured resistance, calculated apparent resistivity, and units
Ground condition, moisture, terrain, access, and observed interferences
Enough locations and spacings for the project’s intended analysis
A clear distinction between field measurements and any separate layer model or inversion

What you receive

Typical project deliverables

Array and test-location plan
Wenner four-pin field measurements
Apparent resistivity calculations
Mapped locations and field documentation

Common project needs

When this service is useful

Grounding-grid design inputs
Transmission and substation projects
Solar and battery facilities
Pipelines, utilities, and corrosion investigations

Nationwide field surveys

Plan the array around the site, asset, and receiving engineer.

Calicore mobilizes for Wenner four-pin programs supporting grounding, substations, solar and battery facilities, wind farms, transmission, utilities, data centers, pipelines, and corrosion evaluations. Every result stays tied to its station, spacing, orientation, measured resistance, field condition, and limitations.

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