Your object is protected from lightning - it is very good. And what to do if billboards will be installed on the roof of the object, while in operation?
Recently, the ZANDZ Technical Center received a request for the development of lightning protection system for billboards installed on the roof of the object in operation. We will see what solution was offered.
Initial data:
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The object is equipped by external lightning protection system in the form of lightning protection mesh. The existing grounding circuit is used as a ground electrode system.
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2 billboards 7900х920х300 mm and 6210х2159х200 mm are installed on the object roof.
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The object height - 40 m.
Task:
Protect billboards from direct lightning strikes.
The set of measures on the implementation of lightning protection system of billboards on the object roof:
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Lightning protection is carried out in accordancde with AD 34.21.122-87 "Instructions on lightning protection of buildings and constructions" and IS 153-34.21.122-2003 Instructions on lightning protection of buildings, constructions and industrial lines.
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The object refers to category 3 of lightning protection. Required lightning protection system reliability – at least 0.9.
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Lightning protection is carried out with the help of air terminals masts 5,7 m high (GL-21105G), fixation to the billboards' bases is carried out with the help of holders (ZZ-203-001), connection to down conductor is carried out with the help of a clamp (ZZ-202-002).
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Copper-bonded steel wire d8 mm e is used as down conductor (GL-11149). Down conductor is connected to the system of external lightning protection of the object.
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Installation of down conductors is carried out with the help of clamp GL-11711 - on the roof. Distance between the clamps- from 0.8 up to 1.0 meter.
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To connect rolled metal with the lightning protection mesh, a universal clamp GL-11551A is used.
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The existing grounding device of the object is used as a grounding device.
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Transient resistance between all metal work and junctions must be not more than 0,05 Ohm at an obligatory annual control before the storm season in accordance with AD 34.21.122-87, item 3.4.
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the density of lightning strikes into the ground - 4 strikes / sq. km per year;
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the total number of strikes into the system: 0.34.
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total number of lightning breakthroughs – 0.021.
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probability of breakthrough into all the system objects - 0.063.
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system reliability – 0,937.
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the average time between lightning strikes into the system (years): 3.
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average time between the breakthroughs, bypassing the protection (years): 48.
Layout of the protected objects and lightning rods arrangement is shown in figure 1.
Figure 1 - Protected objects and lightning rods arrangement layout.
The list of equipment is given in Table 1.
Table 1 - List of equipment and materials.
| № | Product item | Name | Quantity, pcs. | Mass, kg | Note |
| 1. | GL-21105G | GALMAR Vertical lightning rod (air terminal-mast) (5.7 meters) | 4 | 14,8 | |
| 2. | ZZ-203-001 | ZANDZ Fastening for a lightning rod to the wall (stainless steel) | 4 | 14,665 | |
| 3. | ZZ-202-002 | ZANDZ Clamp to the lightning rod D42 mm for down conductors (stainless steel) | 4 | 0,43 | |
| 4. | GL-11711 | GALMAR Clamp on a flat roof for the down conductor (plastic, concrete) | 24 | 1 - 1,2 | |
| 5. | GL-11551A | GALMAR Clamp for connecting down conductors (painted galvanized steel) | 4 | 0,07 | |
| 6. | GL-11149-20 | GALMAR Copper-bonded wire (D 8mm / S 50 mm²; coil 20 meters) | 1 | 0,41 | In meters |
Do you have questions or you need to calculate lightning protection system for billboards on the object roof? Send your request to info@zandz.ru.
See also: