Earthing (Grounding) Calculator
Calculate earth rods and conductor by soil resistivity.
The Earthing (Grounding) Calculator is a free tool designed for construction professionals and enthusiasts. Calculate earth rods and conductor by soil resistivity. Instantly get the required materials broken down by purchase units, with an option to add a wastage allowance so you never run short on site.
Inputs
Result
Result
How to Use This Calculator
- Determine the total circuit power in watts (W) or kilowatts (kW).
- Measure the total cable run in meters (outward + return).
- Enter the installation voltage (230 V single-phase or 400 V three-phase).
- Enter the maximum allowable voltage drop (max 3 % residential, 5 % industrial).
- Click 'Calculate' to get cable cross-section, current and actual voltage drop.
Frequently Asked Questions
Per standard regulations, the maximum voltage drop is 3 % for residential and lighting circuits and 5 % for other uses.
General-purpose outlet circuits use 2.5 mm² cable; large appliance circuits use 4 mm². Lighting circuits use 1.5 mm².
If the circuit feeds wet areas (bathroom, kitchen, outdoor) or equipment with higher contact risk, a high-sensitivity RCD (30 mA) is mandatory.