What matters most
ASTM G57-20 is a test method centered on soil-resistivity measurement using the Wenner four-electrode arrangement and a removed-soil option, commonly used in corrosion work. IEEE 81-2025 is a broader grounding-measurement guide that includes earth resistivity along with grounding-system and surface-potential measurements. The project specification and intended use determine which applies.
Key takeaways
- Do not call the standards interchangeable.
- G57 is commonly specified for corrosion-oriented soil data; IEEE 81 is commonly specified for grounding work.
- A survey can sometimes satisfy both technical objectives when planned and reported accordingly.
- Always state edition, configuration, units, field condition, and deviations.
The scopes overlap but are not identical
Both documents include four-electrode field measurements used to characterize soil or earth resistivity. ASTM G57 also explicitly addresses removed-soil measurement in its corrosion-focused scope; IEEE 81 covers a wider set of grounding-system measurements and practical concerns.
Using the familiar Wenner name does not by itself establish compliance with either document. The instrument, geometry, checks, field practice, calculations, and reporting must match the selected procedure.
Choose the basis from the engineering decision
A pipeline corrosion study may call for ASTM G57, while a substation grounding study may call for IEEE 81. A utility-scale solar project may reference IEEE grounding guidance and still request G57-formatted data for corrosion or owner criteria.
Clarify the receiving discipline, units, spacing sequence, station plan, and desired electronic format before mobilization. One coordinated survey can avoid duplicate field work when the requirements are compatible.
A shared core of good documentation
Regardless of the governing document, preserve coordinates, direction, spacing, resistance, apparent resistivity, units, equipment, contact or quality observations, surface condition, weather, nearby infrastructure, repeats, and exclusions.
Keep interpretation within scope. The field report can discuss variability and limitations; the grounding engineer or corrosion specialist applies the dataset to the design or asset decision.
If a specification cites an outdated standard, send it with the proposal request. Calicore can report the conflict so the responsible engineer can resolve the governing basis before field work.
This page provides general educational information, not a grounding-system design, cathodic-protection design, installed-system acceptance test, or parcel-wide resistivity conclusion. A Wenner result is apparent soil electrical resistivity for the documented array, spacing, location, orientation, and field condition. The responsible grounding or corrosion engineer must evaluate the complete dataset, earth model, asset geometry, governing documents, and uncertainty.
Frequently asked
Questions about this topic
Which standard is better?+
Neither is universally better. The correct choice depends on the governing specification, whether the work supports grounding or corrosion, and the exact measurement requested.
Can one survey be reported to both?+
Sometimes, if the planned equipment, layout, procedure, calculations, and reporting satisfy both applicable requirements. Confirm that before mobilization.
Should an older IEEE 81 citation be updated automatically?+
No. Flag the edition difference to the responsible engineer or owner and document the agreed basis.
Primary references and further reading
- ASTM International — ASTM G57-20 Official record for the Wenner four-electrode field and four-electrode soil-box method.
- IEEE Standards Association — IEEE 81-2025 Current IEEE guide for measuring earth resistivity, grounding-system impedance, and earth-surface potentials.
- Soil Tests Laboratory — Wenner Four-Pin Testing Calicore Engineering’s testing division and field-service information.