From the series of articles "Lightning protection of residential and public buildings - answers to frequently asked questions in the design".
Life in the Soviet Union accustomed the older generation to an excessively respectful relation towards the standards. We cannot say it is a really bad habit. A high-quality standard definitely protects against foolishness, provided that it is not contained in the regulations. The socialist system did not acknowledge private property, and this was the reason of many absurdities in relation to lightning protection requirements. Until now, the current national standard "Instructions for lightning protection of buildings and structures AD 34.21.122-87" strictly regulates protection against direct lightning strikes of industrial buildings, exterior industrial plants, public buildings, even cowhouses, but in relation of residential houses it is applied on the residual principle. The matter is brought to the point of absurdity. Children in school (Public building!) should be protected, the same kids at home - it is quite another matter, clearly less significant.
I don't know whether all of you studied Table 1 of the standard AD 34.21.122-87 till the end, which contains the requirements for lightning protection. It gives information about residential buildings in the very end, after chimneys and pigstries. Here protection is required in exceptional cases where the buildings exceed 25 m array of surrounding buildings within the radius of 400 m or with their own height of over 30 m they are removed from any other buildings of not less than 400 m. Today, there is no one to ask why the number 400 was assigned such magical properties. Though I believe it is meaningless to ask such questions. I don't think anyone is able to explain how a single-storey hut on chicken legs, distant from a ten-story building to 400 meters, frees it from external lightning protection devices.
The volume of lightning protection is defined by the customer
Another 10 - 15 years ago, such a seditious header could not appear in a scientific article. Its author would have certainly been accused of anarchism and irresponsibility. Let's give up labeling. If to take an unbiased look at the regulations on lightning protection, one will have to admit that the regulatory task comes down to the determination of minimum requirements to lightning protection, which should provide a normal life of the protected object in the thunderstorm atmosphere, its occupants, as well as the neighboring buildings, which could suffer in case of emergency. It is clear that the necessary requirements for lightning protection of a residential house and a complex technical object, for example, an oil tank farm, will be fundamentally different. A modern building of brick or concrete, won't be destroyed or set on fire by lightning, people inside the building will not be affected, and for the neighboring houses it won't matter if your house has lightning rods or not, there won't be any hazardous affect on them. That is why these dwellings do not cause much concern for the inspection authorities. That is why, there is almost indifferent attitude to the normalization of their lightning protection, as noted in the previous section.
The house is built on private money, not small money at all. The owner will be fairly concerned about the potential loss of property. He has the right to know what and to what extent can be damaged by lightning, the probability of emergency situation and how much the means of lightning protection will cost for an almost 100% risk elimination. All these data will be requested from the designer, and only then, having received a comprehensive response, the developer decides whether he needs a more reliable lightning protection compared with those miserable crumbs that are prescribed by AD 34.21.122-87.
The designer should be prepared for the answer. For that, he should assess the frequency of direct lightning strikes into the projected building and the frequency of its hazards through electromagnetic field of the lightning discharge.
E. M. Bazelyan, DEA, professor
Energy Institute named after G.M. Krzyzanowski, Moscow
Read more "Counting the frequency of lightning strikes into the building".
Useful materials:
- Series of articles about lightning protection for beginners
- Series of webinars about grounding and lightning protection with Professor E. M. Bazelyan
- Elements of external lightning protection
- Consultations on the selection, design and installation of grounding and lightning protection systems