Simplified lightning risk assessment based on NFPA 780 using Sparkta Software.

1. Designing Lightning Protection Systems
using Sparkta
NFPA 780 Simplified Risk Assessment
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2. Lightning Protection Systems Optimal Design (Add… and Evaluate…)
 Optimal design is an iterative process which consists of adding one or few air terminals and evaluates the lightning strike
frequency each time.
 The air terminals are added in the most likely lightning strike points.
 The process stops when the lightning strike frequency is tolerable.
Four Steps
 Step 1: Physical modeling
 Step 2: Risk assessment without lightning protection. Calculate the yearly lightning strike frequency Nd and the tolerable
lightning frequency Nc. If Nd > Nc the installation of a lightning protection system is recommended. If you decide to install it go
to step 3.
 Step 3: Identify the most likely lightning strike points and add air terminals at these points.
 Step 4: Calculate the yearly lightning strike frequency to the structure Nd. If Nd > Nc repeat steps 3 and 4.

3. Example 1
 Industrial facility with multiple buildings
 Isolated structure
 Non metallic roofs
 Non metallic structures
 2 flashes/km2/year

4. Physical data
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Roofs are modeled as quadrilaterals
Other shapes consist of two or more quadrilaterals
Hexagon: 2 quadrilaterals
Octagon: 3 quadrilaterals
Settings for the simulation

5. Plan view

6. 3D view

7. Graphic Results

8. Results
 Strikes per year for each range of current
 Strikes per year for each roof

9. NFPA 780 Simplified Risk Assessment Using Collection Area Formulas
 Collection area calculated for the
highest structure
 Collection area calculated for an
equivalent rectangle

10. NFPA 780 Simplified Risk Assessment Using flashes per year
 Flashes per year calculated using the
results of the simulation
 The yearly lightning strike frequency Nd is greater than the tolerable lightning frequency Nc – Nd > Nc
Installing a lightning protection system is recommended!!

11. Identify the most likely lightning strike roofs
 Add 4 air terminals and simulate

12. Graphic Results

13. Evaluate results
 Nd > Nc
 It is required to install more air
terminals

14. Identify the most likely lightning strike roofs
 Add 18 air terminals and simulate

15. Graphic Results

16. Evaluate results
 Nd > Nc
 It is required to install more air
terminals

17. Identify the most likely lightning strike roofs
 Add 3 air terminals and simulate

18. Graphic Results

19. Evaluate results
 Nd > Nc
 It is required to install more air
terminals

20. Identify the most likely lightning strike roofs
 Add 2 air terminals and simulate

21. Graphic Results

22. Evaluate results
 Nd < Nc
 No more air terminals are required

23. Example 1 Final Design

24. Example 2
 The same example 1 facility
 Isolated structure
 Non metallic roofs
 Non metallic structures
 10 flashes/km2/year
Settings for the simulation
 The design for 10 flashes/km2/year requires more air terminals than the design for 2 flashes/km2/year. So we can begin with the
example’s 1 final design.

25. Graphic Results

26. Evaluate results
 Nd > Nc
 It is required to install more air
terminals

27. Identify the most likely lightning strike roofs
 Add 11 air terminals and simulate

28. Graphic Results

29. Evaluate results
 Nd > Nc
 It is required to install more air
terminals

30. Identify the most likely lightning strike roofs
 Add 2 air terminals and simulate

31. Graphic Results

32. Evaluate results
 Nd < Nc
 No more air terminals are required

33. Example 2 Final Design

34. Example 3
 The same example 1 facility
 Isolated structure
 Non metallic roofs
 Non metallic structures
 40 flashes/km2/year
Settings for the simulation
 The design for 40 flashes/km2/year requires more air terminals than the design for 10 flashes/km2/year. So we can begin with
the example’s 2 final design.

35. Graphic Results

36. Evaluate results
 Nd > Nc
 It is required to install more air
terminals

37. Identify the most likely lightning strike roofs
 Add 9 air terminals and simulate

38. Graphic Results

39. Evaluate results
 Nd > Nc
 It is required to install more air
terminals

40. Identify the most likely lightning strike roofs
 Add 5 air terminals and simulate

41. Graphic Results

42. Evaluate results
 Nd < Nc
 No more air terminals are required

43. Example 3 Final Design

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