Substation Grounding Grid Design — IEEE 80

electrical

Designs substation grounding grids per IEEE 80-2013. Calculates grid resistance (Sverak), ground potential rise, tolerable step and touch voltage limits, actual mesh and step voltages, and performs safety checks.

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Grid Length M*

Length of the grounding grid in meters. Typically matches the substation fence line or equipment pad footprint. Typical: 30-200 m for distribution substations, 200-500 m for transmission.

Grid Width M*

Width of the grounding grid in meters. Typically matches the substation fence line or equipment pad footprint. Typical: 20-150 m. Should encompass all equipment with margin.

Conductor Spacing M*

Center-to-center spacing between parallel grid conductors in meters. Typical range: 3-7 m. Closer spacing reduces mesh voltage but increases material cost.

Burial Depth M

Depth of grid conductor burial below finished grade in meters. IEEE 80-2013 typical: 0.3-1.0 m. Deeper burial reduces step voltage but increases installation cost. If omitted, defaults to 0.5 m.

Soil Resistivity Ohm M*

Measured soil resistivity in ohm-meters. From Wenner 4-pin test or soil borings. Typical range: 10-10,000 ohm-m depending on soil type and moisture.

Fault Current A*

Maximum symmetrical ground fault current at the substation in amperes. From short-circuit study or utility data. Typical: 5000-40000 A for distribution, 20000-80000 A for transmission.

Fault Duration S

Fault clearing time in seconds. Determined by protective relay and breaker operating time. IEEE 80 typical: 0.25-1.0 s. If omitted, defaults to 0.5 s.

Surface Material

Surface layer material above the grid. Crushed rock (2500 ohm-m typical) greatly increases tolerable touch/step voltages per IEEE 80. Native soil provides no additional protection. If omitted, defaults to crushed_rock.

Surface Layer Depth M

Thickness of the surface material layer in meters. IEEE 80 typical: 0.08-0.15 m (3-6 inches) of crushed rock. If omitted, defaults to 0.1 m.

Surface Resistivity Ohm M

Resistivity of the surface layer material in ohm-meters. Wet crushed rock: 2500; dry crushed rock: 5000+; concrete: 200-500; native soil: use soil_resistivity value. If omitted, defaults to 2500 ohm-m.

Body Weight Kg

Assumed body weight for tolerable voltage calculations in kilograms. IEEE 80 uses 50 kg (child) or 70 kg (adult). Use 50 kg for areas accessible to the public. IEEE 80 standard: 50 kg (conservative) or 70 kg (typical adult). If omitted, defaults to 70 kg.

Conductor Diameter Mm

Diameter of the grid conductor in millimeters. Common sizes: 4/0 AWG copper = 11.68 mm, 2/0 AWG = 9.27 mm. Must be sized for fault current per IEEE 80 Eq. 37. If omitted, defaults to 10 mm.

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This calculator pulls live values from the following engineering reference tables in the database.

grounding grid design

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Substation Grounding Grid Design — IEEE 80 is part of the Engineering Database calculator suite. Each tool runs deterministic calculations against authoritative reference data and code-compliant methods, so results are reproducible and traceable to source standards.

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