Calculator Inputs
Plotly Graph
The chart compares the estimated conductor area for each material using the selected protection level and impulse duration.
Example Data Table
| Scenario | Building Size | Level | Material | Ng | Air Terminals | Down Conductors | Recommended Area |
|---|---|---|---|---|---|---|---|
| Warehouse | 30 × 20 × 15 m | III | Copper | 4.0 | 7 | 7 | 45 mm² |
| Office Block | 42 × 28 × 24 m | II | Aluminum | 5.0 | 12 | 14 | 105 mm² |
| Industrial Shed | 60 × 35 × 18 m | IV | Galvanized Steel | 3.0 | 11 | 10 | 125 mm² |
Formula Used
This calculator combines practical planning formulas for collection area, air terminal coverage, conductor thermal sizing, and basic earthing estimates.
-
Roof area:
Roof Area = Length × Width -
Equivalent collection area:
Collection Area = (L × W) + 2H(L + W) + πH² -
Weighted annual strike exposure:
Exposure = Ng × Collection Area ÷ 1,000,000 × Exposure Factor × Occupancy Factor -
Air terminal coverage radius:
Coverage Radius = √(2Rh − h²)
Here, R is rolling sphere radius and h is terminal height. -
Air terminal quantity:
Count is based on roof coverage and perimeter spacing. The larger planning value is used. -
Down conductors:
Down Conductors = Ceiling(Perimeter ÷ Allowed Spacing) -
Conductor area:
Area = I × √t ÷ k
Here, I is design current, t is impulse duration, and k depends on material. -
Single rod resistance:
R = ρ ÷ (2πL) × [ln(4L ÷ d) − 1]
Final rod count is estimated by comparing single rod resistance against the target value.
How to Use This Calculator
- Enter the building length, width, and height.
- Set the local lightning flash density value.
- Adjust exposure and occupancy factors for site importance.
- Choose the protection level required by your design brief.
- Select the conductor material you want to assess.
- Enter terminal height, impulse duration, and earthing values.
- Press the calculate button to view the result summary.
- Review conductor size, terminal count, down paths, and rods.
- Use the chart to compare material sizing outcomes.
- Export the summary as a CSV or PDF report.
Frequently Asked Questions
1) What does this calculator size?
It estimates conductor cross section, air terminal quantity, down conductor count, total conductor length, and ground rod needs for a preliminary lightning protection concept.
2) Is this enough for final construction drawings?
No. It supports early planning only. Final drawings should follow the relevant protection standard, bonding rules, material limits, and a qualified engineer’s review.
3) Why does protection level change the result?
Each level changes rolling sphere radius, mesh spacing, down conductor spacing, and design current. Stricter levels usually increase material demand and terminal density.
4) What is Ng?
Ng is lightning flash density. It describes the average number of lightning flashes per square kilometer per year for the project location.
5) Why is a minimum conductor area still enforced?
Materials need practical minimum sizes for durability, corrosion allowance, mechanical strength, and standard compliance. Thermal math alone may suggest smaller sections.
6) Can I compare different materials quickly?
Yes. The Plotly chart compares estimated conductor area requirements for all listed materials using your selected level and impulse duration.
7) Does the grounding estimate include every field condition?
No. Soil layering, seasonal moisture, electrode spacing, bonding paths, and test results can change actual earth resistance significantly.
8) When should I use the CSV or PDF export?
Use export when you want a quick record for internal review, budgeting, design meetings, or comparing several building options before detailed engineering.