Earthing and Grounding Calculators
Earth rod, rods in parallel, earth grid, neutral earthing resistor and earth fault loop impedance calculators with formulas and assumptions.
Earthing design starts from soil resistivity and ends with a measured value on site. The calculators estimate the resistance of a single rod, of several rods allowing for mutual interference, and of a buried grid. The neutral earthing resistor calculator sizes a resistor for a chosen earth-fault current, and the fault loop impedance check confirms that an earth fault draws enough current for the protective device to operate.
Where to start
- Earth Rod Resistance: Resistance to earth of a single vertical rod.
- Earth Rods in Parallel: Combined resistance of several rods allowing for mutual interference.
- Earth Grid Resistance: Resistance of a buried grid from soil resistivity, area and conductor length.
- Earth Fault Loop Impedance: Check that an earth fault operates the protective device.
All 5 calculators in this category
Earthing
- Earth Rod Resistance: Resistance to earth of a single vertical rod. Open in Elecmetric
- Neutral Earthing Resistor: Resistance and short-time power of a neutral earthing resistor for a chosen earth-fault current. Open in Elecmetric
- Earth Rods in Parallel: Combined earth resistance of several rods allowing for mutual interference. Open in Elecmetric
- Earth Grid Resistance: Resistance of a buried earthing grid from soil resistivity, grid area and total conductor length. Open in Elecmetric
Electrical Safety
- Earth Fault Loop Impedance: Check that an earth fault draws enough current to operate the protective device. Open in Elecmetric
What these calculators do not cover
Soil resistivity varies with moisture, temperature and depth, so a calculated resistance is an estimate to be confirmed by measurement on site. Step and touch voltage, transferred potential and lightning protection are not calculated here.
Cross-check: all 5 calculators listed here are compared with 34 reference calculations written separately from the engine. This confirms the arithmetic and selection rules. It does not confirm that a standard table or convention matches your standard or manufacturer data.
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