Calculadora de Profundidad de Varilla de Tierra — 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.
**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.
- L = 8 x 0.3048 = 2.438 m
- a = 0.3125 x 0.0254 = 0.00794 m
- R = 100 / (2 x pi x 2.438) x ln(4 x 2.438 / 0.00794)
- R = 6.527 x ln(1228) = 6.527 x 7.11 = 46.4 ohms
- Exceeds 25 ohms; install a second rod at least 6 ft away.