This simulator models step potential — the ground-voltage gradient a person's two feet can span near a grounding system during a fault — using an explicitly simplified, homogeneous-soil hemispherical electrode model. Inject a timed ground fault, adjust soil resistivity, electrode geometry, foot spacing and body/contact resistance, and watch the surface-potential field and the resulting step voltage develop and clear.
• A real-time 3D scene of the current injection point, buried ground electrode (hemisphere), the surface-potential field, bonded accessible equipment and the two measurement foot positions, with home view, focus-selected-part, toggleable enclosure cutaway, auto-rotate, expand and show/hide labels controls. • A Grounding workbench tab with a labeled parts index (fault injection, buried ground electrode, surface potential field, bonded accessible metal, measurement positions, remote return reference) and click-to-inspect component callouts. • Fault, earth & measurement fixtures: applied ground-fault current (100–10,000 A), uniform soil resistivity (10–1,000 Ω·m), equivalent electrode radius (0.5–30 m), distance from injection center (1–30 m), radial foot spacing (0.1–2 m), assumed body resistance (500–3,000 Ω), resistance of each foot contact (0–5,000 Ω) and fault duration (0.1–2 s). • Playback controls: pause/resume, single step, larger step, and four playback speeds (0.1×, 1×, 10×, 60× laboratory speed), plus an 'Apply timed ground fault' / 'Clear fault now' action pair. • A Potential-profile analysis tab with two live charts, the underlying model equations (Rg, Vsurface(r), GPR, Vstep, Ibody) and snapshot measurement readouts. • An Experiments tab with four guided fixtures (reference fault, higher soil resistivity, changed geometry, contact/return effect) and a Model verification bench that runs independent deterministic checks against a fresh model without disturbing your live experiment, plus a timestamped event log and a copyable trial report. • A Learn & assess tab with guided lessons, a knowledge-check quiz with reset, and a written model-scope statement with an OSHA reference link.
When fault current enters resistive soil through a grounding electrode, it raises the local grounding system's potential relative to remote earth — this is ground potential rise (GPR). Outside the equivalent electrode radius, surface potential falls off approximately as 1/r, so two feet placed at different radial distances from the injection point sit at different potentials.
Step voltage is simply the difference between those two foot potentials. Because the field decays with distance, step voltage is generally largest close to the electrode and shrinks farther away — but the model deliberately holds potential uniform inside the electrode radius as a teaching simplification, not a solved conductor mesh.
The simulator converts open-circuit step voltage into an assumed body-circuit current using Ibody = Vstep / (Rbody + 2·Rfoot), where Rfoot is the resistance of each foot's contact with the ground. Raising foot-contact resistance lowers the calculated body current without changing the open-circuit exposure voltage itself — an important distinction the model deliberately separates.
This is a homogeneous, quasi-static hemispherical-earth model with a constant-potential interior — it does not represent a solved IEEE 80 ground-grid calculation, real mesh gradients, multilayer soils, transferred potentials or physiological injury thresholds, and it makes no safe/unsafe classification. A site-specific engineering grounding and exposure assessment is required for any real installation.
Step potential is the voltage difference between two points on the ground surface, roughly one stride apart, that a person's feet could span near an energized grounding system during a fault. It arises because ground potential rise decays with distance from the current injection point, so the two feet sit at different potentials.
Surface potential is directly proportional to soil resistivity for a fixed injected current and geometry. In the simulator, increasing soil resistivity from 100 to 500 Ω·m raises surface potentials fivefold, since Vsurface(r) = ρ·Ig / [2π·max(a,r)].
It reduces the assumed body-circuit current calculated by the model, since Ibody = Vstep / (Rbody + 2·Rfoot), but it does not change the open-circuit step voltage itself — the exposure voltage that exists at that location is unaffected. The simulator deliberately separates these two effects.
No. This is a homogeneous, quasi-static hemispherical-earth teaching model with a constant-potential interior — it omits real ground-mesh gradients, multilayer soils, transferred potentials and exposure variability, and it makes no safe/unsafe determination. A site-specific IEEE 80 grounding and exposure analysis is required for any real installation.