Calculadora de Profundidad de Varilla de Tierra Gratis
Calcula la profundidad necesaria de la varilla de puesta a tierra según el tipo de suelo y la resistividad.
Ground Resistance
0.0 ohms
Ground Resistance vs Soil Resistivity
Fórmula
## Ground Rod Resistance **R = (rho / (2 x pi x L)) x ln(4L / a)** Where rho is soil resistivity in ohm-meters, L is the rod driven depth in meters, and a is the rod radius in meters. The NEC requires a single ground rod to achieve 25 ohms or less; otherwise a second rod is required.
Ejemplo Resuelto
8-ft ground rod (5/8 in diameter) in 100 ohm-m soil.
- 01L = 8 x 0.3048 = 2.438 m
- 02a = 0.3125 x 0.0254 = 0.00794 m
- 03R = 100 / (2 x pi x 2.438) x ln(4 x 2.438 / 0.00794)
- 04R = 6.527 x ln(1228) = 6.527 x 7.11 = 46.4 ohms
- 05Exceeds 25 ohms; install a second rod at least 6 ft away.
Preguntas Frecuentes
What does soil resistivity depend on?
Soil resistivity varies with moisture, temperature, mineral content, and soil type. Wet clay may be 10-50 ohm-m, while dry sand or rock can exceed 1,000 ohm-m.
What if one rod does not meet 25 ohms?
The NEC (250.56) requires a supplemental ground electrode if the first rod exceeds 25 ohms. Two rods are always acceptable regardless of resistance.
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