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Lightning Protection BS

This document contains a lightning protection calculation for evaluating the need for lightning protection on structures according to BS 6651. It details formulas for calculating the collection area of different structure types, including rectangular buildings, towers, and sloping roofs. It also includes factors for flash density, risk of being struck, and an overall risk factor. The calculation is shown for a sample structure and the recommendations are to provide lightning protection as the overall risk factor is between the thresholds of 1x10-5 and 1x10-4.

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643 views6 pages

Lightning Protection BS

This document contains a lightning protection calculation for evaluating the need for lightning protection on structures according to BS 6651. It details formulas for calculating the collection area of different structure types, including rectangular buildings, towers, and sloping roofs. It also includes factors for flash density, risk of being struck, and an overall risk factor. The calculation is shown for a sample structure and the recommendations are to provide lightning protection as the overall risk factor is between the thresholds of 1x10-5 and 1x10-4.

Uploaded by

jonyoliu
Copyright
© Attribution Non-Commercial (BY-NC)
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as XLSX, PDF, TXT or read online on Scribd
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Lightning Protection Calculation

Calculation for Evaluating Need for Protection - by BS6651 1. Collection Area, Ac (sqm) 1.1. Rectangle Building Lengthm Width m 50 14 1.2. Tower Radius m 10 Height m 30 Collection Area Ac sqm 5026.6 Formula: Ac=(H+R)2 Height m 15 Collection Area Ac (sqm 3326.9 Formula: Ac=LW+2LH+2WH+H2

1.3. Sloping Roof (Here pitch 45,if pitch <45,adopt 1.1) Collection Lengthm Height Area Ac m sqm Formula: Ac=H2+2LH 20 30 4027.4 2. Flash density, Ng (per/sqkm) Thunderstor m days per year Td 20 Note: adopt for north Africa 3. Risk of being struck, p 4. Overall risk factor Page 1/of 6 Flash density, Ng (per/sqkm) 1.10 3.7E-03

From Curve of Table 6

Formula: p=AcNg10-6

Lightning Protection Calculation


1 Risk of being struck, p A 2 3 4 5 6 7 8 Overall Overall risk multiplying factor (product factor of columns 1 (product of and 7) columns 2 to 6) 9 Recommendations

Use of structure (Table 8)

Weighting factors B C D Type of Contents or Degree of construction consequential isolation (Table 9) effects (Table 11) (Table 10) 0.4 0.3 1.0

E Type of country (Table 12)

3.7E-03

0.3

0.3

0.011

3.95E-05

protection recommended

Note: Risk less than 110-5 do not generally require protection; risk between 110-5 and 110-4 protection is recommended; risk greater than 110-4 require protection.

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Lightning Protection Calculation

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Lightning Protection Calculation

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Lightning Protection Calculation

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Lightning Protection Calculation


Note: This curve is made from Table 6 of BS 6651

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