This presentation explains briefly the lightning protection system design with various building aspects

1. Lightning Protection
System -Design

2. index

3. Introduction Lightning is not only spectacular, it’s dangerous, it is a giant spark of
electricity in the atmosphere between clouds, the air, or the ground which
causes damage to Humans, Animals, buildings. So the function of a lightning
protection system is to protect structures from fire or mechanical destruction
and persons in the buildings from injury or even death.

4. Risk Assessment
Calculation – Step
1

5. Factor Definition
Nd Expected yearly lightning strike frequency to the structure
Nc Tolerable lightning striking frequency to the structure
Ng Average flash density in the region per year
Ae Equivalent collective area of structure in sq.km.
C1 Environmental coefficient
C2 Structure coefficient
C3 Structure contents coefficient
C4 Structure occupancy coefficient
C5 Lightning consequence coefficient
H Height of building
Table - 1

6. C 1 Relative Structure Location
0.25 Structure surrounded by taller structures within a distance of 3H
0.5 Tolerable lightning striking frequency to the structure
1.0 Average flash density in the region per year
2.0 Equivalent collective area of structure in sq.km.
Table – 2
Ae = LW + 6H(L+W) + 9 π 𝐻2
Nc = (1.5 * 10−3
) / (C2 * C3 * C4 * C5)

7. Ng - Determination

8. C2 Roof material
Structure
Material
Metal Non-metallic Combustible
Metal 0.5 1.0 2.0
Non-metallic 1.0 1.0 2.5
Combustible 2.0 2.5 3.0
Table – 3
C 3 Structure Contents
0.5 Low value and noncombustible
1.0 Standard value and noncombustible
2.0 High value and moderate combustibility
3.0 Exceptional value, flammable liquids, computer or electronics
4.0 Exceptional value, irreplaceable cultural items
Table – 4

9. C4 Structure Occupancy
0.5 Unoccupied
1.0 Normally occupied
3.0 Difficult to evacuate or risk of panic
Table – 5
C 5 Lightning Consequence
1.0 Continuity of facility services not required , no environmental impact
5.0 Continuity of facility services required , no environmental impact
10.0 Consequences to environment
Table – 6

10. Calculation

11. LPS Class LPS Efficiency
1 98%
11 95%
111 88%
1V 81%
Table – 7
C 5 Lightning Consequence
1.0 Continuity of facility services not required , no environmental impact
5.0 Continuity of facility services required , no environmental impact
10.0 Consequences to environment
Table –8

12. Table - 9
APPLICATION LPS CLASS
Computer center, military applications, nuclear power
stations
I
Ex zones in industries and chemical sectors II
Photovoltaic systems >10kW III
Museums, schools, hotels with more than 60 beds III
Hospitals, Churches, storage facilities, meeting
places accommodating more than 100 to 200 people
III
Administrative buildings, sales points, offices and
bank buildings of over 2000sq.m.
III
Residential buildings with more than 20 apartments,
multistorey buildings over 22m high
III
Photovoltaics III

13. Design of LPS
Components– Step
2

14. Vertical Air Termination - Conventional Franklin Rod

15. Design of Vertical Air Termination

16. Rolling Sphere Method
• To identify the areas of a building or
structure that needs protection from lightning
• Wherever the surface of the sphere comes
into contact with the structure is deemed to
be unprotected, thus requiring air
termination.
LPS Class
Radius of
sphere
1V 60m
11I 45m
11 30m
1 20m
Table -10

17. Mesh Method
• Used for protection of flat / sloped roof
surfaces and shouldn’t be used for curved
roof LPS Class Mesh Size
I 5x5m
1I 10x10m
1I1 15x15m
1V 20x20m
Table -11

18. Down conductor Design
• It conducts lightning current from air
termination to earth termination system
• Inorder to reduce damage due to lightning
current circulating in the LPS, down
conductors must be arranged to ground the
current
LPS Class Mesh Size
I 10m
1I 10m
1I1 15m
1V 20m
Table -12

19. Earth termination system
• Continuation of air termination system and
down conductors
• Discharges lightning current to earth and
establishes a equipotential bonding between
down conductors
System
Earth resistance
(ohm)
Low current 0.5-1
Low voltage 5
Medium
voltage
2.5
High voltage 0.5
Lightning
Protection
10
Table -13

20. Summary

21. Thank You