Earthing system
This tool calculates the grounding resistance of an earthing system based on soil resistivity, electrode type, and geometric parameters. It helps verify compliance with IEC 60364-4-41 for coordination between earth electrodes and residual current devices (RCBOs). The calculated resistance is compared to the safety voltage limit (typically 50 V or 25 V) to ensure safe operation and proper tripping of protective devices.
Input Parameters:
• Type of ground electrode – Physical form of the grounding element:
- Rod
- Horizontal rope
- Ring
- Mesh network
• Soil Type – The type of soil where the electrode is installed. Used to estimate resistivity (ρ). Typical values:
- Agricultural: 10–150 Ω·m
- Sandy gravelly: 50–300 Ω·m
- Clay: 50–200 Ω·m
- Marine sands: 200–3000 Ω·m
- Rocky: 1500–10000 Ω·m
- Custom: User-defined value
• Quantity (n) – Number of parallel grounding electrodes used.
• Length (L) – Total length of the grounding conductor in meters.
- For Rod: depth of the vertical rod
- For Horizontal rope: total length of the conductor
- For Ring: circumference of the ring
- For Mesh network: total length of all buried conductors
• Resistivity (ρ) – Soil resistivity in ohm-meters (Ω·m). If not measured, use typical values from soil type.
• Safety Voltage – Maximum allowable touch voltage:
- 50 V: Normal dry environments
- 25 V: Wet, confined, or high-risk locations
Usage Tip:
Enter the parameters and calculate the grounding resistance. Then check if:
R ≤ U₀ / IΔn
Where:
R = Ground resistance (Ω)
U₀ = Safety voltage (50 V or 25 V)
IΔn = Rated residual operating current of RCBO (e.g., 0.03 A for 30 mA)
Example: For 30 mA RCBO and 50 V safety limit:
R ≤ 50 / 0.03 ≈ 1667 Ω → System is acceptable if R < 1667 Ω.
