Ground Grid Analysis and Testing

FAQ

What is a ground grid and why does it need to be analyzed and tested?

A ground grid is a network of buried conductors and electrodes that provides a low-impedance path for fault currents to safely dissipate into the earth. Ground grids are essential safety infrastructure at substations, electrical facilities, and industrial sites — protecting personnel from dangerous touch and step voltages during fault events and providing a stable reference potential for electrical equipment. Over time, ground grids can deteriorate due to corrosion, soil disturbance, and connection failures, making periodic analysis and testing essential to verify continued safety and performance.

Bopat Electric provides comprehensive ground grid analysis and testing services including soil resistivity measurements, ground resistance testing, touch and step voltage measurements, ground grid integrity testing, and full ground potential rise (GPR) analysis. Bopat Electric’s engineers assess the performance of your grounding system against applicable safety standards and provide detailed findings and recommendations for any improvements required.

Ground potential rise (GPR) is the voltage that develops on a grounding system when fault current flows through the earth resistance of the ground grid during a fault event. GPR analysis calculates the magnitude of this voltage rise and the resulting touch and step voltage hazards at the facility. Ground grid analysis and GPR studies are closely related — a thorough ground grid assessment includes GPR analysis to ensure the grounding system adequately protects personnel and connected infrastructure during worst-case fault conditions.

Bopat Electric’s ground grid analysis and testing services are performed in accordance with IEEE 80 — the industry standard guide for safety in AC substation grounding — as well as IEEE 81 for ground resistance measurement techniques, applicable NFPA standards, and OSHA requirements. All work is carried out by qualified engineers with specialized expertise in grounding system analysis and high voltage safety.

Touch voltage is the potential difference between a grounded metallic structure and the surface of the earth at the point where a person is standing while touching that structure. Step voltage is the potential difference between two points on the earth’s surface separated by one pace. Both are direct consequences of GPR during a fault event and can be lethal if they exceed safe limits. Ground grid analysis calculates both touch and step voltages and assesses them against the safe limits defined in IEEE 80 to ensure personnel protection.

Ground grids should be tested periodically to verify continued performance — particularly after any significant changes to the facility’s electrical system, after excavation or ground disturbance near the grounding system, or when equipment additions increase the available fault current. As a general best practice, ground resistance testing should be performed at least every three to five years, with more frequent testing for aging systems or high-criticality facilities. Bopat Electric can assess your grounding system and recommend an appropriate testing schedule.

Bopat Electric provides ground grid analysis and testing services throughout Maryland, Virginia, and Washington DC, and through the BCES Global network of subsidiary companies, across the rest of North America.

Contact Bopat Electric at our Columbia office at 410-995-1715 or our Frederick office at 301-694-3726, or reach us through the request form at bopatelectric.com. Our engineering team will assess your grounding system requirements and provide a scoped proposal for analysis, testing, and any recommended improvements.