Service

Electrical Resistivity Test

Non-destructive geophysical survey mapping subsurface soil, rock, and groundwater — for earthing design, borewell siting, and site investigation.

  • IS Code compliant
  • Own laboratories
  • 5,000+ projects
Get Free Consultation

Overview

An electrical resistivity test measures how strongly the ground resists the flow of electric current. It is a non-destructive geophysical method that maps subsurface soil layers, rock depth, groundwater zones, and fractures — without extensive excavation or drilling.

GeoDesign carries out resistivity surveys for residential, commercial, industrial, and infrastructure projects. Results support earthing and grounding design, borewell siting, foundation planning, and geological investigation.

Why resistivity testing is used

Resistivity surveying covers ground quickly and non-destructively, which makes it valuable both as a standalone investigation and as a way to target where boreholes should go. It is also the standard basis for electrical earthing design, where soil resistivity directly determines the earthing arrangement required.

Common applications:

  • Earthing and grounding system design
  • Groundwater exploration and borewell siting
  • Mapping rock depth and soil stratification
  • Locating fractures, cavities, and weak zones
  • Preliminary investigation over large sites
  • Targeting borehole locations before drilling

For earthing design in particular, resistivity is not optional — the design cannot be completed without it.

Why clients choose GeoDesign

Resistivity data is only as good as its interpretation. Field measurement is straightforward; converting apparent resistivity into a defensible subsurface model requires experience with local geology.

  • Experienced geotechnical and geophysical engineers
  • Vertical electrical sounding and resistivity tomography
  • Interpretation using specialist inversion software
  • Familiarity with regional soil and rock profiles
  • Results linked to your engineering decision, not just plotted
  • Reporting suitable for design and approval

Where results are ambiguous we say so, and recommend confirmatory drilling rather than overstating what a geophysical survey can resolve.

Our resistivity survey services

Survey type and layout are selected against the depth of interest and the question being answered.

  • Vertical Electrical Sounding (VES)

    Layered resistivity profile at a point, identifying soil layers, rock depth, and groundwater zones with depth.

  • Electrical Resistivity Tomography (ERT)

    Two-dimensional subsurface imaging along a survey line, showing lateral as well as vertical variation.

  • Soil resistivity for earthing design

    Measurement to the arrangement required for grounding system design, reported in the form the electrical designer needs.

  • Groundwater exploration

    Identification of potential water-bearing zones to guide borewell siting and depth.

  • Subsurface geological mapping

    Mapping of soil and rock formations, fractures, and cavities across a site.

  • Interpretation & recommendations

    Inversion, interpretation, and engineering recommendations based on the resulting model.

How the survey runs

Resistivity surveys are quick in the field; the value is in planning and interpretation.

  1. Step 1: Site inspection

    Assessment of site conditions, access, and survey objectives.

  2. Step 2: Survey planning

    Array type, electrode spacing, and survey locations selected for the target depth.

  3. Step 3: Field measurement

    Resistivity readings taken across the planned array using calibrated equipment.

  4. Step 4: Data processing

    Apparent resistivity inverted into a subsurface model using specialist software.

  5. Step 5: Interpretation

    The model is interpreted against local geology and the project question.

  6. Step 6: Report

    Findings, sections, and engineering recommendations issued.

Where it is applied

Resistivity surveying supports both construction and water supply work.

  • Buildings & developments

    Residential, commercial, and institutional projects.

  • Industrial facilities

    Earthing design for plants, substations, and warehouses.

  • Infrastructure

    Roads, bridges, metro, and government infrastructure projects.

  • Water supply

    Borewell siting and groundwater development.

Technical reference

Resistivity sits alongside vane shear, permeability, plate load, and chemical analysis in our field testing reference.

Specialised Field Testing →

Areas we serve

Resistivity surveying needs a clear run of ground for the electrode array, which shapes where it can be deployed on constrained urban sites. We survey across:

  • Central Chennai

    Anna Nagar · Adyar · T. Nagar · Guindy · Velachery · Porur

  • South Chennai

    Tambaram · Pallavaram · Chromepet · Medavakkam · Sholinganallur · Perungudi · OMR · ECR · Navalur · Siruseri · Kelambakkam

  • North & West Chennai

    Ambattur · Avadi · Madhavaram · Red Hills · Poonamallee

  • Nearby Regions

    Chengalpattu · Sriperumbudur · Oragadam · Maraimalai Nagar · Kanchipuram

We also undertake projects across Tamil Nadu based on project requirements.

Frequently asked questions

What is an electrical resistivity test?

It is a geophysical survey that measures the ground’s resistance to electric current in order to infer subsurface conditions — soil layers, rock depth, groundwater zones, and fractures. It is non-destructive and requires no drilling.

Why is it used before construction?

It maps subsurface conditions across a site quickly, which supports foundation planning and helps target where boreholes should be drilled. For electrical earthing design, soil resistivity is a required input.

Can it replace borehole investigation?

No. Resistivity gives good spatial coverage but infers conditions indirectly. Boreholes give direct sampling and measured strength at specific points. The two are complementary, and resistivity is often used to decide where boreholes should go.

Is it reliable for locating borewell points?

It is the standard method for identifying zones more likely to be water-bearing, and it substantially improves the odds compared with drilling blind. It indicates favourable conditions rather than guaranteeing yield.

How long does a survey take?

Most surveys are completed within a day of field work, depending on the area covered and the number of soundings, with data processing and reporting following.

What does the report include?

Survey layout, field data, interpreted resistivity sections, identified layers and their depths, groundwater observations where relevant, and engineering recommendations.

Related services