Recently, the ZANDZ Technical Center has performed calculation of a lightning protection system for an athlete rehabilitation and restoration center in the Ural Federal District.
Such facilities are classified as conventional in terms of lightning protection according to SO 153-34.21.122-2003 Guidelines for Mounting Lightning Protection of Buildings, Structures, and Industrial Utilities (hereinafter referred to as SO), and as Category 3 with the protection zone B according to RD 34.21.122-87 Guidelines for Mounting Lightning Protection for Buildings and Structures (hereinafter referred to as RD).
In accordance with RD 34.21.122-87 the automobile repair shop is classified as per category III of lightning protection and shall be protected against direct lightning strikes and high potential penetration through the above ground (overhead) metallic infrastructure.According to these regulatory documents, the structures should be protected from direct lightning strikes and high potential penetration through the above ground (overhead) metallic infrastructure. External installations classified as Category III in terms of lightning protection should be protected from direct lightning strikes. Potential effects of the lightning strike may include failure of power supply and fire alarm systems.
Protection of buildings against lightning strikes is provided by using lightning arresters. Lightning arrester is a device that is elevated over the protected facility through which the lightning current goes into the ground bypassing the protected facility. It consists of a lightning rod that accepts the lightning discharge directly, a current collector, and a grounding electrode.
Calculation of protection zones of repeated lightning arresters is performed according to items 2.2 and 3 of Appendix 3 to RD 34.21.122-87 for zone B. The protection zone of the repeated lightning arresters is defined as a protection zone of the pairs of adjacent lightning arresters. Taking into account that the distance between the lightning arresters is greater than the height but lower than six heights of lightning rods, we can use the respective set of formulas:
Since lightning rods have different heights, we will use the following formulas to calculate sizes of internal area of protection zones:
The set of arrangements ensuring compliance with the lightning protection requirements is based on the following solutions:
- installation of 4 x 4 m lightning rods on the wall. It is considered that 1 m of the rod length is used for securing.
- Installation of 1 x 1.5 m lightning rod near the gutter. It is considered that 0.5 m of the rod length is used for securing.
- Two lightning rods installed on the building, letter B, are used for lightning protection.
- One of towers is not covered by the protection zone. It is used as a lightning rod and the wire is connected to it using clamps ZZ-005-064;
- Lightning rods are interconnected to arrange two current collectors using galvanized steel wire D = 8 mm from each lightning rod. Current collectors are mounted (with mounting step 0.6-1 m):
- connection and branching of current collectors are made using clamps GL-11551А.
A set of activities to provide the necessary requirements to the grounding devices conforms to item 2.26 of RD 34.21.122-87 and is provided by the following solutions:
- mounting of a grounding arrangement consisting of a horizontal electrode (galvanized steel strip with a cross-section 4 x 30 mm), depth of 0.5 meter, and six vertical electrodes (steel copper-clad pins with a diameter of 14 mm), 3 m long;
- interconnection of vertical and horizontal electrodes is carried out using clamps ZZ-005-064;
- соединение токоотвода с выводом оцинкованной полосы из земли осуществляется с помощью control clamps GL-11562A;
- the design of the grounding arrangement corresponds to clause 1.7.55 of the EIC. Grounding devices of protective grounding and grounding for lightning discharges are common.
The location of the elements of the lightning protection system and the grounding arrangement is shown in the drawing. The indicated protection zone corresponds to the zone B according to RD.
The activities are made in accordance with the EIC, Rev. 7, Chapter 1.7, SO and RD.
Table 1. List of required materials.
Do you have any questions about lightning protection for the cadet school or other facilities? Please, contact the ZANDZ Technical Center!