Calcolatrice Resistenza di Terra Gratuita

Calcola la resistenza del dispersore di terra.

ohm-m
m
mm

Ground Resistance

35.12 ohm

Ground Resistance vs Soil Resistivity (rho)

Vedi formula →

Formula

## Ground Rod Resistance The resistance of a ground rod depends on soil resistivity and rod geometry. ### Formula (simplified for vertical rod) **R = (rho / 2 pi L) ln(4L / d)** where rho is soil resistivity in ohm-metres, L is rod length, d is rod diameter, and ln is the natural logarithm. Lower resistance is better for safety. Most codes require < 5 ohms for power systems and < 25 ohms for lightning protection.

Esempio Risolto

A 3 m x 16 mm ground rod in soil with 100 ohm-m resistivity.

  1. 01d = 0.016 m
  2. 02ln(4 x 3 / 0.016) = ln(750) = 6.62
  3. 03R = 100 / (2 x pi x 3) x 6.62 = 100/18.85 x 6.62 = 35.12 ohm
  4. 04This exceeds 5 ohm. Multiple rods or soil treatment may be needed.