Webinar "Grounding and lightning protection for apartment buildings and commercial facilities", page 1

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

During our third webinar, we will proceed to considering the aspects of calculations and installing grounding for apartment buildings and commercial facilities (hypermarkets, warehouses, pavilions, etc.). What is their difference from other facilities? What difficulties may arise and how to negotiate with the customer?

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Approximate reading time: 34 minutes.

Grounding and lightning protection for apartment buildings and commercial facilities

— Let us greet you in our third webinar of the "Simply about installing grounding and lightning protection" series. In the previous webinars, we discussed the regulatory framework that the electrical specialist have to deal with, as well as grounding and lightning protection for the private house, which is probably the most popular facility. Today, we will consider apartment buildings and commercial facilities. These are also popular facilities for performing installation. The electrical specialists have many questions about how to do that correctly, how to negotiate with the customers, and other questions. Our lecturer is Sergei Alekseevich Tolstopyatov, the director general of NGN Group, a representative of the ZANDZ Expert Club and an experienced electrical specialist. So, you will have a unique chance to obtain valuable information at first hand. I am Aleksey Korytko. I am the webinar administrator. I will respond to your comments in the chat. Let me remind you that we have moderation here, so I will need some time to confirm your questions. The ZANDZ technical specialist is also present in our webinar. He will help us in replying to your questions. You can ask them in the chat. I give the word to Sergei Alekseevich.

— Hello! Let us start our webinar. I want to say that I will hold the webinar without pauses. We have engineers to answer your questions. During the webinar, you can ask your questions, they will answer them, and Aleksey will moderate the questions intended for me personally or those questions who may be missed by the engineers. At the end of the webinar, we will return to them and I will answer them, if possible. So, let us start the webinar. I want to remind you my favorite proverb: "If you do not know where to go, then you will likely reach another place". So please do not hesitate to ask questions. It does not hurt to ask! The ZANDZ Project actively and thoroughly helps its clients and customers by answering their questions. We help in design calculations, provide design documents so that you could correctly use specifications and product ranges you intend to use. This is particularly important for the government orders, so that the articles you specify in the design would correspond to the article numbers of the GALMAR equipment imported by ZANDZ in Russia. In this case, we do not recommend to take the product range directly from the GALMAR catalogue, because they are slightly different. And then, upon approval with the government customer of the product range that is taken from the GALMAR catalogue and the product range that is certified in Russia, difficulties may occur.

Lightning protection of apartment buildings and commercial facilities

— So, today we will consider the grounding and lightning protection of large facilities, apartment buildings and commercial facilities. I will tell you how the lightning protection and grounding of the commercial facilities and apartment buildings are performed and what you need to pay attention to during the design and installation. The specific features of these structures usually include large area in case of warehouse and hypermarkets, and significant height in case of apartment buildings. You need to protect both structural and process elements, such as venting pipes, lights, gas vents in the gas boilers, including the gas boilers located on the roof. 

Lightning protection of a hypermarket

— To provide lightning protection for the hypermarket, regular lightning rods are installed on the building roof that provide the protection zones depending on the height they are installed at, and the zone combination. 

Protection reliability calculations

— So, by installing the required number of lightning rods, the facility along with its process elements will be fully located in the protection zone. The reliability requirements are usually specified in terms of reference during calculations. Such zones as A, B are distributed according to governing document 34, and the zones with reliability ratio of 0.8 to 0.999 are distributed according to instruction 153. Choosing the required protection method depends on the facility type, its fire and explosion safety, as well as on the individual customer requirements, or special requirements of the regulatory authorities, which may be determined by the location of environmentally hazardous facilities nearby, such as filling stations, if any, some residential premises and, as I have already mentioned, parking lots. Usually, the fire-hazardous buildings are protected in accordance with zone A (according to RD-34), or with reliability of 0.99-0.999. If the building has not got any fire and explosion hazardous zones, then it is sufficient to protect it as zone B with the reliability of 0.9. To calculate the grounding reliability, we usually use the special software developed by the Energy Institute named after Krzhizhanovsky. The software is recommended for use by the Bulletin of Roselektromontazh Association shown in the slide. The calculations are performed for the buildings of any configurations and any lightning rod arrangements, e.g., as shown in the previous slide. To perform calculations, provide us with terms of reference. If you do not know how to formulate it clearly then do it as you can and, if possible, send us the buildings photos. We will help you understand and calculate it correctly and in accordance with the building reliability.

Layout of current collectors from the lightning rods

— Along the roof perimeter as well as higher and lower levels, the current collectors are installed that are interconnected by the lightning rods. They must be installed such that each lightning rod has at least two current collectors. 

Lightning protection grid

— In this case, the lightning protection grid we discussed above is shown. We can use it for the lightning protection of II and III categories in the cases if the roof slope does not exceed 1 : 8. This is associated with the fact that, with the significant slope, the strikes will be concentrated in the ridge area and in the top region; therefore, the grid will be ineffective in a separate part. Moreover, the grid has equivocal protection efficiency in terms of protection against the direct lightning strike. The lightning may strike in any grid point or even the grid cells with the same probability as the grid is usually slightly lifted above the roof. The grid advantages include current flowing. It improves the situation strongly in terms of electromagnetic compatibility, i.e. the absorption of large amounts of electrical energy and its distribution on the grounding system. With multiple fragmentation of the lightning current, the electromagnetic field impact reduces significantly. So, we cannot say that the grid may protect the building against the direct lightning strike and even talk about the protection reliability. 

Lightning protection grid (continued)

— Compared to the rod or wire lightning protection systems, to install the grid, large amount of materials, wire and clamps for the installation to secure the grid to the surface, and to connect the intersections, are used.

Metal roof as the lightning rod

— In the course of designing and installation, you should pay attention to the possibility of using the metal roof itself as the lightning rod. This is permitted in RD-34 and SO 153. To do this, all roof elements must have a continuous electrical coupling. For the roof metal to serve as the lightning rod, you should meet the following condition: for iron, the metal thickness should be at least 4 mm. If you need to protect the roof against damage, otherwise the lightning may burn the metal through. 

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