29.07.15
Nowadays glass buildings are very popular both inside and outside the city. Like any other buildings, glass facades are also in need of a reliable lightning protection.
Of course, such a design requires a special, thoughtful solution.
We invite you to study lightning protection calculation for the administrative building in the city of Saint- Petersburg, made with the use of glass.
1. Facility
One-storey building, exterior building envelope walls are made of aerated concrete 30 cm thick and covered with ceramic granite slabs on metal frame. Part of the building walls is made of glass.
Scheme of the building, side view
кровельные металлические панели типа сэндвич - roofing metal panels of "sandwich" type
стекло - glass
Top view
Стекло - glass
Газобетон с защитным покрытием – aerated concrete with protective coating
2. Task
It is necessary to calculate and design external lightning protection system consisting of lightning rods, down conductors and a ground electrode system.
3. Solution
According to the documents EIC 7th ed. and Industry Standard 153-34.21.122-2003 the object "administrative building" refers to the usual type of buildings and to the third category of lightning protection. The required reliability of lightning protection system - 0.9.
Protection of buildings from lightning strikes is carried out by means of lightning dischargers (lightning rods). Lightning rod presents itself a device rising above the protected object, through which the lightning current, bypassing the protected object, is diverted into the ground. Air terminal masts are used as lightning rods in this case. The following actions are carried out to ensure the required reliability of lightning protection:
- installation of two lightning rods 4.7 m and 5.7 m high, combined by the down conductor made of copper-bonded wire with a diameter of 8 mm;
- installation of five vertical grounding electrodes each 3 m long, which are united by a copper-bonded tape with the cross-section 30 mm wide and 4 mm high. The embedding is done to the depth of at least 0.5 m. The distance from the ground electrode to the foundation is 1 m, between the electrodes - not less than 5 m.
Detailed description of lightning protection arrangement:
Lightning protection of the object is made with the installation of air terminal masts GL-21105G and GL-21104G. Fixation of down conductors GL-11149, which present themselves copper bonded wire is performed on flat surfaces by means of clips GL-11747A and GL-11706, and on vertical surfaces - using clamps GL-11703A. Distance between the clips - from 0.8 up to 1.0 meter. To connect down conductors over the length and in the mesh nodes, a universal clamp GL-11551A is used. Air terminal masts are mounted on vertical surfaces with the help of holders GL-21201, connection of down conductors is performed with the help of clamps GL-20023. 3-meter vertical electrodes, consisting of ground pins ZZ-001-065 are used as a grounding device. Copper-bonded tape GL-11075 is the horizontal conductor.
The results of the calculation performed by the software, developed by JSC "Energy Institute to the name of G. M. Krzizhanovsky"( JSC "ENIN"):
- the density of lightning strikes into the ground - 6 strikes / sq. km per year;
- the total number of breakthroughs (strikes directly into the object passing lightning rods) - 0.00021 (4391 times per year);
- protection reliability - 0.922.
Arrangement of all elements of external lightning protection system is shown in the figure below.
Side view
Top view
List of equipment for the implementation of a reliable lightning protection of the object:
Important:
For a complete protection from direct and secondary lightning effects, it is necessary to organize a system of internal lightning protection based on proper selection of protective devices Surge (SPDs) in addition to external lightning protection.
To understand all the details of SPDs choice for low-voltage networks read the article on a separate page.
Book a free consultation and calculation of grounding and lightning protection systems for your property! Our technical specialists will be happy to help you!
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