Soil measurements (Wenner method)
Enter the meter readings, compare apparent resistivity and carry the result into the calculation.
Check which meter you have. This calculator is only for converting readings from meters that do not measure soil resistivity automatically. If your meter measures resistivity, you do not need this calculator.
Meter readings
- Enter the meter readings: for each measurement, give the electrode spacing a and the resistance R read from the meter. The white fields are for your input.
- We calculate the resistivity ρₐ in the last column. Click “Measurement 1”, “Measurement 2”… to view the electrode layout and the result of that measurement.
| Measurement | Electrode spacing a [m]enter | Meter reading R [Ω]enter | ρₐ [Ω·m]result | Remove |
|---|---|---|---|---|
| 100.53 | ||||
| 94.25 | ||||
| 80.42 | ||||
| 70.37 |
Model of electrodes with negligible depth relative to the spacing. Reading R is the resistance measured with the four-electrode array.
Four-electrode array
WennerFrom measurement to calculation
The selected value is taken as an assumption of uniform soil. Compare the results of different measurements before choosing a design value. You can carry the result into the ring earth plan (step 2) to calculate the ring earth resistance, or straight into the earthing calculator (step 3).
How does apparent resistivity change?
Compare rows by selecting “Measurement 1”, “Measurement 2”… in the table. The chart is not a cross-section of soil layers; a larger spacing measures a larger volume of soil.
Method, scope and sources
ρₐ = 2πaR, a in metres, R in ohms. If electrode depth is not negligible, a geometric correction is needed, which this model does not include. The measurement requires equal spacing of the four electrodes. Results from different spacings and directions are not averaged automatically.
Megger: measurement method · EPA: apparent resistivity and interpretation
Ring earth calculator
The result of the selected measurement (Measurement 1, ρₐ = 100.5 Ω·m) will be carried into the ring earth plan as the soil resistivity, and on to the earthing calculator.