The first of September is in that means a new academic year for the schools, colleges, institutes, universities and other educational institutions. It is very desirable to equip such facilities with the lightning protection systems since a large number of people gather inside them. The colleges are the specialized secondary educational institutions that provide secondary or primary vocational education. Such facilities are classified as common according to the regulatory documents and do not imply special lightning protection option. However, it is important to preserve the aesthetics of the building. The ZANDZ Technical Center has received a request to calculate the lightning protection of the college in the Khanty-Mansiisk Autonomous District. A special feature of the facility is the non-standard roof structure. Let us continue with more detailed review of our offered solution.
Calculation of the lightning protection of the college in the Khanty-Mansiisk Autonomous District
Figure 1 – Object layout.
Facility: college in the Khanty-Mansiisk Autonomous District
Task: calculation of the lightning protection system for the college in the Khanty-Mansiisk Autonomous District
Solutions to fulfil the requirements for the lightning protection system of the college in Langepas:
- The lightning protection is made in accordance with Electrical Installations Code (EIC), Rev. 7, SO 153-34.21.122-2003 "Guidelines for the lightning protection of buildings, structures and industrial infrastructure" (hereinafter referred to as SO) and RD 34.21.122-87 "Guidelines for the lightning protection of buildings and structures" (hereinafter referred to as the RD).
- According to RD, the facility is considered as the 3rd category lightning protection facility. The system reliability shall be at least 0.9.
- Lightning protection of the facility is made using 2 lightning arresters (masts) with a height of 2 m installed on the roof ridge (GL-11521SS) and 2 lightning arresters (masts) with a height of 4 m installed on the holders to the walls (ZZ-201-004), 1 m for the mount and 3 m up.
- A copper-plated steel wire (copper coating thickness of 70 μm min.), d8 mm (GL 11149) is used as a down conductor.
- The down conductors are installed using the holder GL-11564A on the roof ridge, using the holder GL-11747A on the roof pitches, using the holder GL-11703A on the vertical surfaces. The accepted pitch of terminals is 0.8-1.0 m.
- The universal terminal GL-11551A is used to connect rolled products along the length and in joints.
- All metal elements located on the roof must be connected to the main conductor cable with the terminals GL-11545. Stairs, railings, are attached using the terminal-clamp GL-11514N.
- The vertical copper-plated steel electrodes with the length of 3 m are used as the grounding devices at the downdrops of the down conductors. The copper-plated steel strip with a cross-section of 30x4 mm, combining all vertical electrodes is used as a horizontal ground electrode. The distance to the object foundation is at least 1 m. Strip deepening is 0.5 to 0.7 m.
- According to EIC-7 issue, par.1.7.55 - Grounding devices for protective grounding of electrical installations for buildings and structures and the 2nd and 3rd categories lightning protection of these buildings and structures, as a rule, shall be common.
- If there are concrete-steel constructions, they shall be connected to down conductors/grounding device.
- Connection to the grounding device is carried out using ZZ-005-064 clamps.
Results of calculation performed using the software developed by Krzhizhanovskiy Energy Institute OJSC (KEI OJSC):
Intensity of lightning discharge into the ground is 4 strikes/square km per year.
Total number of strikes into the system is 0.062 (times per 16 years).
The total number of breakouts in the system is 0.0047 (once every 213 years).
The probability of a breakthrough into the system facilities is 0.076.
System reliability is 0,924.
Ground terminal resistance calculation:
The design resistance of the grounding devices is 1,5 ohms.
Figure 2 shows hardware layout.
Table 1 includes the list of required hardware and materials.
Figure 2 - Location of the lightning protection equipment for the college in the Khanty-Mansiisk Autonomous District
Table 1 – List of material requirements.
Do you have any questions about lightning protection of the college or other facilities? Please, contact the ZANDZ Technical Center!