Three calculators, ready to use
Enter your values below for an instant estimate. Each calculator shows the formula it uses, so you can check the working yourself.
How this is calculated+
Rod dimensions should be selected for the electrode design, mechanical strength, corrosion environment and manufacturer/product specification. This calculator is a preliminary mathematical estimate, not a design approval.
This is a preliminary single-electrode estimate. Multi-rod arrays, mutual resistance between electrodes, and seasonal soil moisture variation are not accounted for — confirm with a fall-of-potential test on site.
How this is calculated+
Short-circuit impedance is set by the transformer designer, typically 4–6%. A lower impedance means lower losses but a higher fault current — sometimes high enough that it becomes expensive to clear safely through the earthing system.
If an earth resistance value is entered, the calculator shows the illustrative voltage rise V = I × R at the calculated three-phase fault current. This is not a substitute for an earth-fault current calculation, ground-potential-rise study, or step/touch voltage assessment.
How this is calculated+
Increasing the spacing a probes deeper soil layers, building a picture of resistivity at depth. Most soils have two or three layers — a full multi-layer study needs dedicated software, but this two-layer estimate is a solid starting point.
Take readings at several spacings and average them; a single reading can be skewed by local variation near the electrodes.
Preliminary engineering estimates only, provided for design guidance. Actual earthing performance depends on soil conditions, moisture, and seasonal variation — confirm with on-site testing before finalising an installation. Reference: IS 3043 (Code of Practice for Earthing).