Calculate Lightning Protection for Building / Structure

Example: Calculate Whether Lightning Protection is required or not for following Building. Calculate No of Down Conductor for Lightning Protection

Area of Building / Structure:

  • Length of Building (L) = 60 Meter.
  • Width of Building ( W ) = 28 Meter.
  • Height of Building (H) = 23 Meter.

Lightning Stock Flushing Density

  • Number of Thunderstorm (N)= 80.00 Days/Year
  • Lightning Flash Density   (Ng)=69 km2/Year
  • Application of Structure (A)= Houses & Buildings
  • Type of Constructions (B)= Steel framed encased without Metal Roof
  • Contests or Consequential Effects (C)= Domestic / Office Buildings
  • Degree of Isolation (D)= Structure in a large area having greater height
  • Type of Country (E)= Flat country at any level
  • Maximum Acceptable Overall Risk Factor =0.00000001
Reference Table As per IS:2309
Thunder Storm Days / Year Lightning Flash Density (Flashes to Ground /km2/year)
5 0.2
10 0.5
20 1.1
30 1.9
40 2.8
50 3.7
60 4.7
80 6.9
100 9.2
Application of Structure Factor
Houses & Buildings 0.3
Houses & Buildings with outside aerial 0.7
Factories / workshop/ Laboratories 1
Office blocks / Hotel 1.2
Block of Flats / Residences Building 1.2
Churches/ Hall / Theaters / Museums, Exhibitions 1.3
Departmental stores / Post Offices 1.3
Stations / Airports / Stadium 1.3
Schools / Hospitals / Children’s Home 1.7
Others 1.2
Type of Constructions Factor
Steel framed encased without Metal Roof 0.2
Reinforced concrete without Metal Roof 0.4
Steel framed encased with Metal Roof 0.8
Reinforced concrete with Metal Roof 1
Brick / Plain concrete or masonry without Metal Roof 1.4
Timber framed or clad without Metal Roof 1.7
Brick / Plain concrete or masonry with Metal Roof 2
Timber framed or clad with Metal Roof
Contests or Consequential Effects Factor
Domestic / Office Buildings 0.3
Factories / Workshop 0.3
Industrial & Agricultural Buildings 0.8
Power stations / Gas works 1
Telephone exchange / Radio Station 1
Industrial key plants, Ancient monuments 1.3
Historic Buildings / Museums / Art Galleries 1.3
Schools / hospitals / Children Homes 1.7
Degree of Isolation
Factor
Structure in a large area having greater height 0.4
Structure located in a area of the same height 1
Structure completely Isolated 2

Calculation:

Collection Area (Ac)=(L x W) + 2 (L x H) + 2(W x H) +(3.14 x H2)

  • Collection Area (Ac) = (60×28)+2x(60×23)+2x(28×23)+(3.14x23x23)
  • Collection Area (Ac) =7389 Meter2

Probable No of Strikes to Building / Structure (P)= Ac x Ng x 10-6 No’s / Year

  • Probable No of Strikes to Building / Structure (P)= 7389x69x106 No’s / Year
  • Probable No of Strikes to Building / Structure (P)= 05098 No’s / Year

Overall Multiplying Factor (M) =A x B x C x D x E

  • Application of Structure (A)= Houses & Buildings as per Table Multiplying Factor = 0.3
  • Type of Constructions (B)= Steel framed encased without Metal Roof as per Table Multiplying Factor =0.2
  • Contests or Consequential Effects (C)= Domestic / Office Buildings as per Table Multiplying Factor =0.3
  • Degree of Isolation (D)= Structure in a large area having greater height as per Table Multiplying Factor =0.4
  • Type of Country (E)= Flat country at any level so as per Table Multiplying Factor =0.3
  • Overall Multiplying Factor (M) =0.3×0.2×0.3×0.4×0.3
  • Overall Multiplying Factor (M) =0.00216

Overall Risk Factor Calculated (xc)= M x P

  • Overall Risk Factor Calculated (xc)= 0.00216 x0.05098
  • Overall Risk Factor Calculated (xc)= 000110127

 Base Area of Structure (Ab) = (LxW)

  • Base Area of Structure (Ab)=60×28
  • Base Area of Structure (Ab)=1680 Meter2

Perimeter of Structure (P) =2x (L+W)

  • Perimeter of Structure (P)=2x(60+28)
  • Perimeter of Structure (P)=176 Meter

Lightning Protection Required or Not

  • If Calculated Overall Risk Factor Calculated > Maximum Acceptable Overall Risk Factor than only Lighting Protection Required
  • Here Calculated Overall Risk Factor is 0.000110127 > Max Acceptable Overall Risk Factor is 00000001
  • Lightning Protection is Required

 No of Down Conductor

  • Down Conductors As per Base Area of Structure (s) =1+(Ab-100)/300
  • Down Conductors As per Base Area of Structure (s) =1+(1680-100)/300
  • Down Conductors As per Base Area of Structure (s) =6 No’s
  • Down Conductors As per Perimeter of Structure (t)= P/30
  • Down Conductors As per Perimeter of Structure (t)= 176/30
  • Down Conductors As per Perimeter of Structure (t)= 6 No’s
  • Minimum No of Down Conductor is 6 No’s

 Results:

  • Lightning Protection is Required
  • Down Conductors As per Base Area of Structure (s) =6 No’s
  • Down Conductors As per Perimeter of Structure (t)= 6 No’s
  • Minimum No of Down Conductor is 6 No’s
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About Jignesh.Parmar
Jignesh Parmar has completed M.Tech (Power System Control), B.E(Electrical) from Gujarat University. He has more than 14 years experience in Power Transmission-Power Distribution-Electrical energy theft detection-Electrical Maintenance-Electrical Projects(Planning-Designing-coordination-Execution). He is Presently associate with one of the leading business group as a Deputy Manager at Ahmedabad,India. He is Freelancer Programmer of Advance Excel and design useful Excel Sheets of Electrical Engineering as per IS,NEC,IEC,IEEE codes. He is technical Author for "Electrical Mirror" and "Electrical India" Magazines. He is Technical Blogger and Familiar with English, Hindi, Gujarati, French languages. He wants to Share his experience & knowledge and help technical enthusiasts to find suitable solutions and updating themselves on various Engineering Topics.

18 Responses to Calculate Lightning Protection for Building / Structure

  1. Gopala Krishnan says:

    Very useful datas

  2. Zaw Maung says:

    Thanks a lot. Could you explian about selection of air terminal , surge arrester, please?

  3. Tushar Mahajan says:

    Dear Sir,

    Nice Information

    Thanks Tushar Mahajan.

  4. Hello, do you have any software to simulate the artistic lighting of bridges? – Thank you!

  5. K R Nair says:

    Any one interested to undertake insulation coordination study of HV andEHV Transmission Lines? If so please do contact. Though we performed in the past and performing at present, we wish to oursource this study, if find viable.

  6. Dinesh Kumar Sarda says:

    Dear Sir,

    Thanks for the information. I humbly request you to provide me with a similar working on substations 220 KV and above DSLP calculation. urgently required for an interview. Please help

  7. Prathamesh Bagav says:

    Maximum Acceptable Overall Risk Factor =0.00000001 value is fixed or may change as par building type?

  8. Prathamesh Bagav says:

    Hi Sir, Maximum Acceptable Overall Risk Factor =0.00000001 value is fixed or may changed according to building type?

  9. ayman zaher says:

    there is a missing table
    you referred to 5 factors we already have 4 above
    where is the table of E factor (type of country ) your choice was ( flat country at any level = 0.3 ) its not stated above where is the fifth table

    before i also put a statement about the equation of voltage drop in wires and asked why we use (r cos phi + x sin phi ) instead of sqrt (( rcos phi) 2 + ( x sin phi ) 2 ) and still no answer

    anyways thanks alot for your efforts

  10. ayman zaher says:

    there is something make me confuse about the data input

    in the start of the data input you put
    Maximum Acceptable Overall Risk Factor =0.00000001 and this is 1 to the power -8

    and after the example near the end you put
    Here Calculated Overall Risk Factor is 0.000110127 > Max Acceptable Overall Risk Factor is 00000001

    in the excel sheet we have from your site as you are the author of it you put the overall risk factor is .000001 that means only 1 to the power of -6

    so please advice is it 0.00000001 or 0.000001

    thanks for the efforts in this blog

  11. Mustaqeem Shaikh says:

    Dear sir how to calculate the cable size of lightning arrestor ?

  12. Rupali Patil says:

    Sir, Thanks for your guidelines. One thing i need to confirm this is for rectangular, square types of building. How to calculate No of Down Conductor for Lightning Protection for circular building?

  13. Debasis sahoo says:

    Is earthing of pure metallic structure required?

  14. devang says:

    Dear sir,

    1. Can we connect static earthing system and power [electrical] earthing system?

    2. Which of the earthing pits [Power, instrument, lightning, static, telecommunication] we can interconnect without hazard?

  15. khin shwe says:

    Thank for your information.

  16. Bala says:

    very informative..
    Could you explain about the rolling sphere method

  17. VEENA gore says:

    Jinesh
    Your notes compilation is excellent and I have downloaded that.
    However I want to highlight that this calculation as per is 2309 is no longer applicable now since this IS has become obsolete now. And is replaced by ICE 62305.
    Veena Gore

  18. Sunil R Tripathi says:

    Dear Sir,
    Thanks for these nice information. Sir, what size of cable must be used if my Down conductor increases and whether earth pits are required for each DC. And the distance between these earth pits if applicable.

    Kindly do the needful.

    Sunil.

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