A fire-fighting tank is a wonderful helper for large fires. In idle mode, it is stored in a block-module which performs as a garage. When building this block-module for a fire-fighting tank, it is necessary to make lightning protection system.
ZANDZ Technical Center accepted an inquiry for the calculation of lightning protection systems and grounding of a block-module for storing a fire-fighting tank. The task solution was as follows:
- sizes (l/w/h): 12,7 m х 6m х 7m;
- soil resistivity: 100 Ohm * m
Calculate external lightning protection system and grounding.
The set of measures to provide the required lightning protection for a block-module for storing a fire-fighting tank is offered by the following solutions:
- installation of two lightning rods 5 meters high at the edges of the roof. Distance between the strut palms - up to 1 m (see fig.1); connection of the down conductor is performed with the help of clamp ZZ-202-002;
- lightning rods are united with the help of steel copper-bonded wire d8 mm for the organization of not less than 2 down conductors;
- fixation of down conductors is carried out with the help of clamps GL-11747A on the roof, GL-11703A on vertical surfaces.
- installation of the grounding device according to AD, item 2.26 consisting of 2 vertical electrodes 3 m long, united by the horizontal electrode (copper-bonded tape 30x4 mm). The distance from the horizontal electrode to the object should be not less than 1 m, deepening 0.5 - 0.7 meters.
Grounding device resistance calculation:
The design resistance of the grounding device is 9.16 Ohms, which is less than the required one of 10 Ohm.
Results of calculations for the protection zone in compliance with the IS:
Air terminal mast № 1,2 (ZZ-201-005):
h = 11 m;
Height of the cone according to the IS chart. 3.4
Distance between the lightning rods:
The ultimate distance between the lightning rods, according to the IS chart 3.6:
There is no vertical clearance.
Location of equipment and protection zone are shown in figure 1.
The list of equipment and required materials is given in Table 1.
Figure 1 - Location of equipment.
Table 1 - Materials requirement list.
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