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Grounding System Calculator
Comprehensive grounding calculations per NEC and IEEE 80 standards
Ground Electrode Resistance (Dwight Formula)
NEC minimum: 8 feet
Standard: 5/8" (0.625) or 3/4" (0.75)
Typical: 10-1000 Ω·m
Space rods ≥ 2× rod length apart
Typical Soil Resistivity Values
Sea water0.1 - 1 Ω·m
Wet organic soil10 Ω·m
Moist soil100 Ω·m
Dry soil1000 Ω·m
Clay40 - 100 Ω·m
Sand200 - 2000 Ω·m
Gravel3000+ Ω·m
Bedrock10000+ Ω·m