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Lightning protection and grounding of the courthouse in Yakutia

The ZANDZ Technical Center received a request for the calculation of an external lightning protection system and grounding of the courthouse in Yakutia. Let us consider the solution that was proposed by our experts.

Lightning protection and grounding of the courthouse in Yakutia

Source data:

  • architectural drawings;
  • soil resistivity - 1000 Ohm * m..
 

Task:

  • calculate external lightning protection system;
  • calculate a grounding device with the resistance of not more than 40 Ohm.
 

Solution:

Lightning protection and grounding of the industrial building are made in accordance with:

 

The object refers to III category of lightning protection in accordance with AD and to "ordinary" in accordance with IS.

 

A set of measures to ensure the necessary requirements for a lightning protection system and the grounding device of a multifunctional complex is represented by the following solutions:

  1. Lightning protection is carried out with the help of a lightning mesh with a distance between the cells of not more than 10 m. The mesh is made of steel copper-bonded wire (the tickness of the copper coating is not less than 70 mcm), the diameter of the wire is d8 mm (GL-11149).
  2. Steel copper-bonded wire d8 mm (GL-11149) is used as a down conductor (thickness of the copper bonding at least 70 mcm).
  3. Installation of down conductors is carried out with the help of clamp GL-11711 - on a flat roof, GL-11703A -on vertical surfaces. Distance between the clamps- from 0.8 up to 1.0 meter.
  4. A universal clamp GL-11551A is used for connecting the mill products along the length and in the nods.
  5. All metal elements, placed on the roof must be connected to the down conductor with the help of clamps GL-11545A. Stairs and hand railings are connected with the help of a clamp-bridge GL-11514N.
  6. Down conductors are connected by horizontal belts near the ground and every 20 m along the height of the building, according to IS 153-34.21.122-2003, clause 3.2.2.3.
  7. Copper-bonded steel electrodes 3 m long are used in places of downdrops as vertical ground electrodes. Copper-bonded steel tape with the cross-section of 30x4 mm uniting all vertical electrodes is used as a horizontal ground electrode. The distance to the object foundation- not less than 1 m. Deepening of the tape 0,5-0,7 m.
  8. In accordance with the EIC-7 ed., P.1.7.55 - Grounding devices for protective grounding of electrical installations of buildings and structures and lightning protection of the 2nd and 3rd categories of these buildings and structures, as a rule, should be common.
  9. The calculated value of the resistance of the grounding device is 15.27 Ohms.
  10. If there are metal reinforce concrete framings, they must be connected to down conductors/ grounding device.
  11. Connection to the grounding device is carried out with the help of clamps ZZ-005-064.
 

The resistance calculation of the grounding device:

Vertical electrode resistance:

Vertical electrode resistance:

where ρэкв - equivalent soil resistivity - 1000 Ohm*m;

L - vertical electrode length - 3 m;

d- vertical electrode diameter - 0.014 m;

T- deepening - the distance from the ground surface to the ground electrode system - 2 m;

where t is the deepening of the electrode top - 0,5 m

Horizontal electrode resistance:

whereρ - equivalent soil resistivity - 1000 Ohm*m;

b - width of the horizontal electrode - 0.03 m;

h - horizontal electrode laying depth -0.5 m;

Lгор - horizontal electrode length - 165 m.

 

Impedance of the grounding device:

where n - number of kits, vertical ground electrodes -9 pc., horizontal ground electrode - 1 pc. ;

Kисп - utilization ratio, 0.69.

The design resistance of the grounding device is 15,27 ohms, which is less than the required value of 40 ohms.

 

Figure 1 shows the arrangement of equipment.

Молниезащита здания суда

Figure 1 - Location of equipment.

 

The list of required material is given in Table 1.

 

Table 1 - List of materials needs.

№ Product item Name Quantity, pcs. Mass, kg. Note
1. GL-11149-50 GALMAR Copper-bonded wire (D 8mm / S 50 mm²; coil of 50 meters) 25 0,41 Weight per meter
2. GL-11545A GALMAR Clamp on the gutter for a down conductor (painted galvanized steel) 20 0,112  
3. GL-11551A GALMAR Clamp for connecting down conductors (painted galvanized steel) 200 0,07  
4. GL-11711 GALMAR Clamp on a flat roof for the down conductor (plastic, concrete) 220 1 - 1,2  
5. GL-11703A GALMAR Clamp to the facade for down conductor with its elevation above the clamp to 15 mm (painted galvanized steel) 1300 0,02  
6. GL-11514N GALMAR clamp to the rainwater downpipe for a down conductor (tape of tinned copper + stainless steel clamp) 20 0,076  
7. GL-11075-50 GALMAR Copper-bonded tape (30 * 4 mm / S 120 mm²; coil 50 meters) 4 0,98 Вес за метр
8. ZZ-001-065 ZANDZ Copper-bonded threaded grounding rod (D14; 1.5 m) 18 2,00  
9. ZZ-002-061 ZANDZ Threaded coupler 10 0,08  
10. ZZ-003-061 ZANDZ Starting tip 9 0,07  
11. ZZ-004-060 ZANDZ Driving head for jackhammer 4 0,09  
12. ZZ-005-064 ZANDZ Clamp for connecting conductors (up to 40 mm) 25 0,16  
13. ZZ-006-000 ZANDZ Conductive grease 1 0,10  
14. ZZ-007-030 ZANDZ Waterproof tape 9 0,40  
15. ZZ-008-000 ZANDZ Header for a jackhammer (SDS max) 1 0,50  

Do you have questions about lightning protection and grounding of the courthouse? Contact the ZANDZ Technical Center!

 

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