Grounding Electrode System Calculator
Estimate ground resistance for single rods, parallel rods, ground rings, and ground grids using Dwight's formulas per IEEE 142
Free grounding electrode planning screen for electricians, electrical engineers, and telecom installers who need a preliminary resistance estimate before field verification. Enter measured or assumed soil resistivity, rod dimensions, ring geometry, or grid geometry. The app uses local Dwight-style and simplified grid formulas, shows local 25-ohm and 5-ohm screens, and makes the source gaps visible. It does not determine NEC compliance, AHJ approval, utility acceptance, substation grounding safety, step or touch voltage, fault clearing, bonding, equipment grounding, or final design.
Calculate fault current to verify your grounding system can handle it
Fault Current Calculator →Size wire for grounding electrode conductors
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Conduit Fill Calculator →How It Works
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Enter Soil Resistivity
Enter measured soil resistivity in ohm-meters, or select a soil type from the reference table to use a typical value. Measured values always give better estimates than reference data.
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Select Electrode Type
Choose single rod, parallel rods, ground ring, or ground grid. Each type has different input fields for its geometry.
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Enter Electrode Dimensions
For rods: length, diameter, quantity, and spacing. For rings: diameter, conductor size, and burial depth. For grids: area, conductor spacing, and burial depth.
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Review Results
The screen shows theoretical resistance, local 25-ohm and 5-ohm reference checks, input warnings, and source boundaries. Use field measurements and qualified review for design or compliance decisions.
Frequently Asked Questions
Learn More
Grounding Electrode Planning: Soil, Sources, and Field Tests
Grounding electrode resistance planning with soil-resistivity uncertainty, source gaps, field testing, NEC/AHJ boundaries, and qualified-review cautions.
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