Block-boxes are used for various purposes. Equipment for holding researches, pump stations, operator's rooms can be inside them. Such moveable prefabricated buildings don't require permission for construction and can be erected on the required territory. ZANDZ Technical Center recently recieved a request for lightning protection of a block box. We will study the solutuon we offered in detail.
Calculation of lightning protection of block boxes in Leningrad region
Object: block-boxes in Leningrad region.
Figure 1 - Plan of the object.
Task: Perform calculation of lightning protection system for block-boxes in Leningrad region.
Solutions to meet the requirements to a lightning protection system for block-boxes:
- Lightning protection is carried out in accordance with EIC 7th edition IS 153-34.21.122-2003 «Instructions for lightning protection of buildings, structures and industrial communications» (hereinafter IS) and AD 34.21.122-87 «Instructions for lightning protection of buildings and structures» (hereinafter AD).
- The object refers to category 3 of lightning protection. System reliability must be not less than 0,9.
- Lightning protection is carried out with the help of a lightning mesh with a distance between the meshes of 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).
- Copper-bonded steel wire is used as down conductor (thickness of the copper coating not less than 70 mcm), d8 mm wire (GL-11149).
- Installation of down conductors is carried out with the help of clamp GL-11703А - on the roof and on vertical surfaces. Distance between the clamps- from 0.8 up to 1.0 meter
- To connect rolled metal over the length and in the nodes, a universal clamp GL-11551A is used.
- All metal elements, placed on the roof must be connected to the down conductor with the help of clamps GL-11545. Stairs, railings are connected with the help of GL-11514 clamp.
- Copper-coated steel electrodes 3 m long are used in places of downdrops as a vertical ground electrode. 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. Burial depth of the tape 0,5-0,7 m.
- 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.
- If there are metal reinforce concrete framings, they must be connected to down conductors/ grounding device.
- Connection to the grounding device is carried out with the help of clamps ZZ-005-064.
- In case of presence of the existing grounding device, they should be united into one grounding device in accordance with EIC p.1.7.55.
Grounding device resistance calculation:
The design resistance of the grounding device is 8,85 Ohm.
Figure 2 shows the arrangement of equipment.
Table 1 gives the list of the required equipment and materials.
Figure 2 – Layout of equipment for block-boxes lightning protection
Table 1 - List of need in materials.
Do you have any questions about lightning protection of block-boxes? Please contact our ZANDZ Technical center!
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