Step and Touch Potential Analysis

FAQ

What is step and touch potential analysis?

Step and touch potential analysis is an engineering assessment that calculates the voltage gradients that appear on and around the surface of the earth near electrical grounding systems during a ground fault event. Touch potential is the voltage difference between a grounded metallic structure and the earth surface at the point where a person stands while touching it. Step potential is the voltage difference between two points on the earth’s surface separated by one pace. Both can be lethal if they exceed safe limits, making step and touch potential analysis a critical component of electrical safety assessment at substations, industrial facilities, and any site with significant grounding infrastructure.

During a ground fault event, large fault currents flow through the grounding system and surrounding earth — creating voltage gradients across the site that can expose personnel to dangerous electrical shock hazards without them ever directly contacting energized equipment. These hazards are invisible under normal operating conditions and can only be identified through engineering analysis. Step and touch potential analysis quantifies these hazards and ensures your grounding system design provides adequate protection for all personnel who may be present on or near the site during a fault event.

Step and touch potential analysis is required during the design of new substations and high voltage facilities, when assessing the safety of existing grounding systems, when fault current levels change due to system modifications or utility upgrades, and whenever metallic structures, fences, or external circuits are installed near electrical grounding infrastructure. Regulatory bodies, utilities, and insurers increasingly require documented step and touch potential analysis as evidence of due diligence in electrical safety.

Bopat Electric’s step and touch potential analysis service includes soil resistivity testing, ground fault current calculations, development of a grounding system model, calculation of touch and step voltage distributions across the site, assessment of calculated hazard levels against the safety thresholds defined in IEEE 80, and a detailed engineering report with findings and recommendations. Where hazard levels exceed safe limits, Bopat Electric provides targeted recommendations for grounding system improvements.

A ground potential rise (GPR) study calculates the overall voltage rise of the grounding system during a fault and assesses its impact on connected infrastructure and personnel at the boundary of the site. Step and touch potential analysis focuses specifically on the voltage gradients within and immediately around the site — calculating the actual touch and step voltages that personnel could be exposed to at specific locations. In practice, both analyses are complementary and are often performed together as part of a comprehensive grounding system safety assessment.

Bopat Electric’s step and touch potential analyses are performed in accordance with IEEE 80 — the definitive industry standard for safety in AC substation grounding — as well as applicable OSHA regulations, NFPA standards, and any utility or project-specific requirements. All work is carried out by qualified power systems engineers with specialized expertise in grounding system safety analysis.

Bopat Electric provides step and touch potential analysis 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 facility’s grounding system and provide a scoped proposal for a complete step and touch potential analysis.