Free Earthing Tool

Earthing BOQ Builder

Q: How many earthing pits do I need?

Estimate the resistance of one pit from soil resistivity and electrode size (Dwight formula). Pits in parallel do NOT combine as a simple R_single ÷ target: they share the same soil volume and sit in each other's resistance field, so apply a combining factor and size against the realistic figure. For example a single 3 m × 40 NB pipe in 100 Ω·m soil is about 27.6 Ω; to reach a 5 Ω target you need about 9 pits (achieving roughly 4.8 Ω) once the combining factor is applied — naive R ÷ target would suggest only 6 and miss the target on test. Pits should be spaced at least their own length apart; confirm by measurement.

Q: What materials go into one earth pit?

A conventional pipe earth pit uses one GI earthing pipe (commonly 40 NB × 3 m) as the electrode, grounding salt and charcoal backfill around it to lower soil resistance, a funnel set for watering, an RCC chamber cover, and a bolt-nut set to connect the earthing strip. Pits are linked back to the main earthing terminal with GI or copper strip.

Q: How much salt and charcoal per earth pit?

A common starting figure is about 25 kg of grounding salt and 25 kg of grounding charcoal per pit, layered around the electrode. Quantities vary with pit size and soil; this builder lets you edit the per-pit figures. So 6 pits at 25 kg each need 150 kg of salt and 150 kg of charcoal.

Q: How do I prepare an earthing BOQ?

Decide the pit count (from a resistance target or directly), then tally per-pit materials × pits plus the connecting strip run: GI pipes, salt, charcoal, GI/copper strip, funnel sets, chamber covers and bolt-nut sets. This builder produces that consolidated list and a single WhatsApp enquiry. Confirm the final design with your engineer per IS 3043.

Turn a resistance target (or a pit count) into a complete earthing materials list — GI pipes, salt, charcoal, connecting strip and accessories — then send the whole BOQ as one WhatsApp enquiry. Weights come from the same IS 1239, GEC chart and Dwight data as our standalone calculators.

Soil type / resistivity (ρ, Ω·m)

Target resistance (Ω)

Pipe size (NB)

Pipe length (m)

Salt per pit (kg)

Charcoal per pit (kg)

Connecting strip material

Strip size (mm)

Total strip run (m)

Defaults to 10 m per pit — edit to your site layout.

Accessories (one per pit) Funnel set RCC chamber cover Bolt-nut set

Item	Spec	Qty	Unit	Weight / Notes

Indicative BOQ for budgeting. Final design (pit count, spacing, conductor size, corrosion allowance) must be confirmed by your design engineer per IS 3043.

Send this BOQ on WhatsApp

Please read. These figures are general projections, not a design. They are estimates based on published formulae, standard weight data and assumed uniform soil conditions — real sites vary, and the numbers here may not be 100% accurate. They are offered as a working aid only. Global Electric Company accepts no liability for decisions taken on the basis of these results: always have them checked and signed off by your site engineer, electrical consultant or a qualified professional, and confirm earth resistance by measurement on site before commissioning. Where these tools and IS 3043 disagree, IS 3043 wins.

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GI Strip → Copper Strip → Earthing Plates → GI Pipe →

How the earthing BOQ is built

In design mode the builder estimates one pit’s resistance with the Dwight formula, then sizes the pit count to your target:

R₁ = ( ρ ÷ (2πL) ) × ( ln(8L ÷ d) − 1 )
smallest n where F(n) × R₁ ÷ n ≤ target

Then it multiplies the per-pit recipe by n and adds the connecting strip run. Material weights reuse the exact data from our standalone tools: GI pipe from the IS 1239 (Part 1) nominal weight, strip from the Global Electric Company weight chart, and resistance from the Dwight equation. So a figure here matches the corresponding single-purpose calculator for the same inputs.

Why the pit count is higher than R₁ ÷ target. Pits in parallel never reach R ÷ n, because each electrode sits in its neighbours’ resistance field. Sizing off R ÷ n would sell you too few pits and the installation would miss its target on test. We apply a combining factor F(n) and size against the realistic figure instead. Pipe tonnage assumes medium class. Brickwork, chambers, clamps and GI wire are not included.

Frequently asked questions

How many earthing pits do I need?

Estimate one pit’s resistance from soil resistivity and electrode size. Pits in parallel don’t combine as a simple R_single ÷ target — they share the same soil volume, so apply a combining factor and size against the realistic figure. A 3 m × 40 NB pipe in 100 Ω·m soil is about 27.6 Ω, so reaching a 5 Ω target needs about 9 pits (≈ 4.8 Ω), not the 6 that naive R ÷ target suggests. Space pits at least their own length apart and confirm by measurement.

What materials go into one earth pit?

One GI earthing pipe (commonly 40 NB × 3 m), grounding salt and charcoal backfill, a funnel set for watering, an RCC chamber cover, and a bolt-nut set to land the earthing strip. Pits connect back to the main earthing terminal with GI or copper strip.

How much salt and charcoal per earth pit?

A common starting figure is about 25 kg salt and 25 kg charcoal per pit (editable here). So 6 pits need roughly 150 kg of each — adjust for pit size and soil.

How do I prepare an earthing BOQ?

Fix the pit count (from a resistance target or directly), multiply the per-pit recipe by the pit count, add the connecting strip run, and tally pipes, salt, charcoal, strip, funnels, chamber covers and bolt-nut sets. This builder does that and produces a single WhatsApp enquiry. Confirm the final design with your engineer per IS 3043.