IEEE 80 Grounding Grid Calculator

Substation ground grid touch & step voltage analysis

Input

Grid Geometry

Length X (m)

Length Y (m)

Conductor Spacing D (m)

Burial Depth h (m)

Conductor Diameter d (m)

Ground Rods

Rod Count

Rod Length (m)

Soil Properties

Soil Resistivity ρ (Ω·m)

Protective surface gravel (affects tolerable voltage via Cs)

Gravel ρs (Ω·m)

Gravel Thickness hs (m)

Fault Parameters

Symmetrical Fault Current 3I0 (A)

Fault Duration ts (s)

Body Weight

Fault Current Details (Df, Sf) ▶

Analysis Method

IEEE 80 Closed-Form fast BEM Numerical accurate

Conductor Sizing (Eq. 37)

Material

Max Temp (°C)

Ambient Temp (°C)

Select an example or enter parameters and click Analyze

Voltage Comparison

Grid Layout

Cross-Section

Parameter Sensitivity

Conductor Spacing vs Em

Ground Rod Count vs Em

Key Results

Parameter	Value	Limit	Status

IEEE 80 Intermediate Factors

Symbol	Name	Value

Grid Geometry

Parameter	Value

How This Analysis Works

Overview

This tool performs an IEEE Std 80 grounding grid analysis for electrical substations. It computes grid resistance, ground potential rise (GPR), and evaluates whether touch and step voltages remain within safe limits for personnel during a ground fault.

IEEE 80 Closed-Form Method

The simplified method uses the equations from IEEE Std 80 to estimate mesh (touch) and step voltages based on grid geometry, soil resistivity, fault current, and surface layer properties. Key factors include the spacing factor K_m, irregularity factor K_ii, and the decrement factor D_f for asymmetric fault current.

Boundary Element Method (BEM)

The BEM solver discretizes all grid conductors and ground rods into segments, then solves for the current distribution that produces a uniform potential on the grid. Surface potentials are computed on an evaluation grid to produce touch and step voltage contour maps. This approach captures edge effects and non-uniform current distribution that the simplified method approximates with correction factors.

Two-Layer Soil Model

When enabled, the BEM solver uses the method of images to model a two-layer soil (upper and lower resistivity layers). The reflection coefficient K = (ρ₂ − ρ₁) / (ρ₂ + ρ₁) governs how current reflects at the layer boundary.

Tolerable Voltage Limits

Touch and step voltage thresholds are computed per IEEE 80 using the surface layer derating factor C_s, fault clearing time, and assumed body weight (50 kg or 70 kg). A design is considered safe when both the mesh voltage and step voltage are below their respective tolerable limits.

The Wenner 4-pin soil resistivity tool can derive a two-layer soil model from field measurements and automatically configure the analysis inputs.