Webinar "Grounding and lightning protection for apartment buildings and commercial facilities", page 3

The third webinar of the "Simply about installing grounding and lightning protection" series 

Webinar text. Page 3

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Lightning protection of a sheltered gas boiler house

Молниезащита крышной газовой котельной Lightning protection of a sheltered gas boiler house
При наличии на крыше котельной должны быть защищены продувочные газовые свечи. При этом должно быть соблюдены требования пункта 2.6 РД: Gas vent stacks shall be protected if installed on the boiler house roof. At the same time the requirements of item 2.6 of RD shall be observed:
При наличии на зданиях и сооружениях прямых газоотводных и дыхательных труб для свободного отвода в атмосферу газов, паров и взвесей взрывоопасной концентрации в зону защиты молниеотводов должно входить пространство над обрезом труб, ограниченное полушарием радиусом 5 м. If straight gas vent and breathing stack are installed on the buildings and facilities for free gas, vapor and explosive suspended matter removal into the atmosphere, the space above the stack mouth shall be covered by the lightning arresters protection zone to a limit of 5 m-radius hemisphere.
Для газоотводных и дыхательных труб, оборудованных колпаками или "гусаками", в зону защиты молниеотводов должно входить пространство над обрезом труб, ограниченное цилиндром высотой Н и радиусом R: для газов легче воздуха при избыточном давлении внутри установки: до 25,25 кПа Н = 2,5 м. R = 5 м. For the gas vent and breathing stacks equipped with a hood or goose neck, the space above the stack mouth shall be covered by the lightning arresters protection zone to a limit of the height H and radius R: for volatile gases in case of pressurized plants: up to 25.25 kPa Н = 2.5 m. R = 5 m.
Заземление и молниезащита на ZANDZ.com Grounding and lightning protection on ZANDZ.com

Lightning protection of a sheltered gas boiler house

— Currently, both commercial facilities and warehouses are provided with individual gas boilers. We draw your attention to this. The gas boiler may be installed both on the roof and in the building basement; it necessarily has the stack that pulls out the gas excess and provides venting as well as the boiler gas vent line. Depending on the availability of caps thereon, item 2.6 of RD must be complied with. 

 

Examples of calculations for apartment buildings by using Krzhizhanovskiy ENIN software
 

Примеры расчетов многоквартирных домов при помощи программного обеспечения ЭНИН им. Кржижановского Examples of calculations of apartment buildings by using Krzhizhanovskiy ENIN software
Параметр Parameter
Значение Value
Плотность разрядов молнии в землю, уд./кв. км в год Intensity of lightning discharge into the ground, strikes/square km/year
Полное число ударов в систему Total number of strikes into the system
Суммарное число прорыва в систему Total number of blowouts into the system
Надежность системы System reliability
0,9 (раз в 7 лет) 0.9 (times per 7 years)
0,054 (раз в 17 лет) 0.054 (times per 17 years)
Заземление и молниезащита на ZANDZ.com Grounding and lightning protection on ZANDZ.com

Examples of calculations for apartment buildings by using Krzhizhanovskiy ENIN software

— Here, we want to show you the exemplary calculations for the buildings using the ENIN software developed by Institute named after Krzhizhanovskiy. Let us consider the exemplary calculations of the lightning protection system reliability using this software. The first building we are looking at now is 58 meters high. The protection is made using the lightning rods of 5 and 7 m attached at the venting shafts as well as the lightning rods of 8 meters installed on the elevator shafts. One more time, I draw your attention to the fact that there are only few roofs that do not have any protruding structures. Therefore, in this case, we orient towards the venting and elevator shafts, which are risen above the building roof and can be primary hazardous objects for lightning strikes. Metal railings may also be used as lightning rods. They are usually located along the building perimeter. Reinforced concrete structure of the facility is used as the grounding device in case it is integral. The system we can see in the slide has reliability of 0.918, with the requirement for category III being equal to 0.9. With this building height, as we can see from the table, the lightning strikes into the facility may be rather frequent.

 

A house of 35 meters high
 

Дом высотой 35 м A house of 35 meters high.
Плотность разрядов молнии в землю, уд./кв. м в год Intensity of lightning discharge into the ground, strikes/square km/year
Полное число ударов в систему Total number of strikes into the system
Суммарное число прорыва в систему Total number of blowouts into the system
Надежность системы System reliability
0.29 (раз в 14 лет) 0.29 (times per 14 years)
0.024 (раз в 39 лет) 0.024 (times per 39 years)
Заземление и молниезащита на ZANDZ.com Grounding and lightning protection on ZANDZ.com

A house of 35 meters high

— Here, we can see the building of 35 meters high. The calculations results for the eleven-storied house are provided here. The protection is made using the lightning rod system. The lightning rods of 4 meters high are also secured along the building perimeter. 

 

A warehouse of 12.5 meters high
 

Складское помещение высотой 12,5 м. A warehouse of 12.5 meters high
Параметр Parameter
Значение Value
Плотность разрядов молнии в землю, уд./кв. км в год Intensity of lightning discharge into the ground, strikes/square km/year
Полное число ударов в систему Total number of strikes into the system
Суммарное число прорыва в систему Total number of blowouts into the system
Надежность системы System reliability
0.095 (раз в 53 года) 0.095 (times per 53 years)
0.0066 (раз в 142 года) 0.0066 (times per 142 years)
Заземление и молниезащита на ZANDZ.com Grounding and lightning protection on ZANDZ.com

A warehouse of 12.5 meters high

— Here, we have provided the example of arranging the warehouse lightning protection. This is the case when we either had the roof surface variation more than 1.8 meters or we could not secure the lightning rods directly on the building roof or walls. In this case, the protection was performed using the on-ground lightning rods and wire lightning protection system along the building perimeter. As you can see in the figure, it entirely covers the building from direct lightning strikes. The lightning rods provide protection. If you pay your attention; each lightning rod has its own grounding. However, they are connected into a single circuit.

What surge protection devices should we use?
 

Какие УЗИП применить? What surge protection devices should we use?
УЗИП класса 1; SPD class 1;
УЗИП класса 2; SPD class 2;
УЗИП класса 3; SPD class 3;
УЗИП класса 1+2+3. SPD class 1+2+3.
Рекомендации по установке УЗИП LEUTRON Recommendations for the LEUTRON surge protection device installation
Заземление и молниезащита на ZANDZ.com Grounding and lightning protection on ZANDZ.com

What surge protection devices should we use?

— Here, we want to discuss the issue that is frequently asked. Usually, lightning protection is not limited to physical lightning protection, the lightning rods. When the lightning strikes, an issue arises very often: if the discharge does not go to the ground and will not be absorbed entirely by the grounding system, but goes to the panel board, what can we do in that case? In this case, the surge protection devices (SPDs) are used to protect against over-voltage as a result of secondary lightning effects. We can use several SPDs in the apartment buildings. We recommend using several SPDs. Let us consider what SPDs should we use. In each new apartment building, there is an electric panel board that powers all floors and auxiliaries, etc. Note that, currently, each residential complex must be powered from at least two terminals, and electric supply from each of them must be protected. 

 

Recommendations for the LEUTRON surge protection device installation
Recommendations for the LEUTRON surge protection device installation

— Finally, in this slide, we can recommend using LEUTRON SPDs of class 1 and 2 to protect the facilities equipped with the lightning protection system. Guidelines for quick selection of SPDs can be downloaded here. Once again, do not hesitate to ask questions. It does not hurt to ask! But we will always help you in solving problems.

Questions and answers.

— I am ready to answer your questions now.

— Question from Irina: "What foundation hydro-isolation prevents the current flowing?"

— You know, it would be much easier to say what type of hydro-isolation you have. And we would explain whether it is sufficient to avoid using additional grounding systems. In the 15th slide, we said that bitumen and latex hydro-isolation does not usually affect the grounding resistance significantly. 
 

 

— Question: "How to better secure downdrops to sandwich panels?"

— We have shown you a special fastener, i.e. it entirely depends on the height above the dropdown; therefore, the respective fastener is chosen. As far as I remember, the sets include anchor bolts. If the thickness is suitable, you can do that using the anchor bolts. If not, you can also use the self-tapping screws. If I am wrong then Dmitry will correct me.

— Question: "How can I evaluate the number of downdrops from the lightning grid to the grounding devices?"

— It is easier to send us the request. We will perform calculations for the building. 
 

 

— The question concerning the lightning protection grid and the number of downdrops to the grounding devices: "Is there a minimum number?"

— We have to pay attention to the building area and height. Then, we will be able to calculate and provide, i.e. send us the data you have and we will calculate what you need appropriately. Why guessing when you can obtain the qualified answer with calculations free of charge.

— "Do you mean that there is no minimum number? Does it depend on numerous factors?"

— Yes, and it is primarily cover area.

– Good. Dmitry has already answered all the remaining questions. Vasily's suggestion with regards to the substation for the next webinar and suggestion with regards to the sandwich panel grounding will be considered. Thank you. We have no more questions, so we can finish. Thank you for your participation. Sergei Alekseevich, thank you so much for the presentation!

— We wish you all the best. Thank you! Thank you, guys, for your help. I hope to see you in the next webinars with interesting questions.

— See you soon!
 


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