Soil Resistivity Testing
On-site Wenner four-pin soil resistivity measurements — the essential foundation of every grounding design.
Service Overview
Soil resistivity testing takes the guesswork out of electrical grounding design. Soil resistivity is a function of the concentrations of ionic soluble salts and the moisture level in soil. Soil resistivity testing is done to measure a soil's corrosivity and determines how well or how poorly the soil will conduct electrical current.
Soil resistivity testing is absolutely essential when it comes to reliable electrical grounding design, determining ground potential rise, and calculating the 5-ohm resistance to ground. Knowing how conductive or resistive the soil is can be critical to providing proper safety of equipment and personnel.
A proper soil resistivity test can also save valuable time and money. It takes the guesswork out of the construction and design process and always gives a predictable outcome. The most reliable and widely accepted soil resistivity test in the world today is the Wenner four-pin test method — and it is the standard method used by E&S Grounding Solutions on every project.
Key Benefits
- Wenner four-pin method — the most reliable and widely accepted test method
- Eliminates guesswork from grounding design
- Essential for accurate GPR and resistance-to-ground calculations
- Identifies corrosive soil conditions for cathodic protection design
- Multi-depth measurements for complete soil profile
- Data delivered in a format ready for CDEGS computer modeling
Ready to discuss your project?
+1 310-318-7151Our Process
Site Preparation
Measurement locations selected based on facility layout and grounding system requirements.
Wenner Testing
Four-pin Wenner method testing performed at multiple spacings and orientations to capture full soil profile.
Data Analysis
Soil resistivity data analyzed and multi-layer soil model developed.
Report Delivery
Written report with soil resistivity data, multi-layer model, and recommendations for grounding design.
Standards & Codes
Industries Served
Related Technical Articles
Understanding Soil Resistivity Testing for Electrical Grounding
Soil resistivity testing is the single most critical factor in electrical grounding design. Learn how the Wenner four-pin method works and why it is the industry standard.
What is the Resistance-to-Ground?
Resistance-to-ground is the key metric that soil resistivity data is used to calculate. Learn what values are required by the NEC and IEEE standards for your facility type.
The Mathematical Formula for Calculating Earth Resistance
Learn the Dwight formula for calculating the resistance of a single ground rod and the formula for combining multiple electrodes in parallel — directly derived from soil resistivity data.
What is Step and Touch Potential and Reducing Resistance to Ground?
Soil resistivity directly determines step and touch potential hazards. Learn how resistivity data feeds into IEEE 80 safety calculations for your facility.
Frequently Asked Questions
What is soil resistivity testing?
Soil resistivity testing measures the electrical resistance of the soil at a site using the Wenner four-pin method. The results are used to design grounding systems, calculate resistance-to-ground, and model step and touch potentials. It is the most critical input parameter for any grounding system design.
How is soil resistivity testing performed?
E&S Grounding Solutions uses the Wenner four-pin method, which involves driving four equally spaced electrodes into the soil and measuring the resistance between them at multiple spacings. The data is then processed using computer software to produce a multi-layer soil model used in grounding system design.
How long does soil resistivity testing take?
A typical soil resistivity test at a single site takes 4–8 hours, depending on the number of test traverses required and site access conditions. Results are typically delivered within 5–10 business days as part of a written engineering report.
Is soil resistivity testing required by code?
IEEE 80 requires soil resistivity data for substation grounding design. NFPA 70 (NEC) does not explicitly require soil testing for commercial buildings, but it is strongly recommended for any facility where a specific resistance-to-ground value must be achieved.
Schedule Soil Resistivity Testing
Contact our team of licensed engineers to discuss your project requirements and receive a customized proposal.