The ZANDZ Technical Center has received a request to calculate the lightning protection and grounding system for the reproduction health center in the Voronezh Region.
Let's consider the solution offered by our specialists.
facility: a reproduction health center;
dimensions: 56.3 x 17.1 x 22.6 m;
soil resistivity: 100 Ohm*m.
calculate the lightning protection system;
calculate the grounding device.
Lightning protection and grounding of the building are made in accordance with:
SO 153 34.21.122 2003 "INSTRUCTIONS FOR MOUNTING LIGHTING PROTECTIONS OF BUILDINGS, STRUCTURES AND INDUSTRIAL COMMUNICATIONS", hereinafter referred to as SO;
RD 34.21.122 87 "INSTRUCTIONS FOR MOUNTING LIGHTING PROTECTION OF BUILDINGS AND STRUCTURES", hereinafter referred to as RD.
The facility is classified as “conventional” from the viewpoint of SO and as Category III of the lightning protection according to RD.
A set of measures to provide necessary requirements to the lightning protection and grounding system for the reproduction health center includes the following solutions:
1. The facility lightning protection is performed using the lightning grid made of a steel copper-plated wire d8 mm. Grid step is at least 10 m. A grid is made using a steel zinc-plated wire d8 mm (ZZ-502-008).
2. Metal caps should be provided on all air shafts that will function as natural lightning arresters.
3. Steel zinc-plated wire d8 mm (ZZ-502-008) is used as a current collector.
4. Current collectors are connected by horizontal bands near the ground and each 20 m along the building's height according to SO 153-34.21.122-2003, item 188.8.131.52.
5. Current collectors are installed using clamp ZZ-202-015 on the roof and GL-11703A on ramparts and vertical surfaces. The clamp installation step is 0.8 to 1.0 m.
6. The multifunctional GL 11551A clamp is used to connect the rolled products over the length and in assemblies.
5. All metal elements located on the roof must be connected to the down conductor using GL-11545A clamps. Stairs, railings, are attached using the GL 11514N ring clamp.
8. 3 m steel zinc-plated electrodes in the points of downdrop connections are used as vertical ground electrodes. A galvanized steel strip with a cross-section of 30x4 mm, combining all vertical electrodes is used as a horizontal ground electrode. The distance to the facility foundation is at least 1 m. Strip deepening is 0.5 to 0.7 m.
9. According to EIC-7 issue, item 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 usually should be common.
10. If there are reinforced concrete structures, they should be connected to current collectors or to the grounding device.
11. Connection to current collectors is performed with the step not more than 20-25 m using clamps ZZ-005-064.
Ground terminal resistance calculation:
Vertical electrode resistance:
Верт - Vert
Экв - Eq
Ом - Ohm
where ρρeq – is equivalent soil resistivity, 100 Ohm·m;
L – is vertical electrode length, 3 m;
d – is vertical electrode diameter, 0.016 m;
T – is depth, i.e. the distance from the ground surface to the ground electrode, 2 m;
м - m
where t – is deepening of the top of the electrode, 0.5 m.
Horizontal electrode resistance:
Гор - Hor
Ом - Ohm
where ρ – is soil resistivity, 100 Ohm·m;
b - is horizontal electrode width, 0.03 m;
h - is horizontal electrode depth, 0.7 m;
Lгор – is horizontal electrode length, 164 m.
Electrical impedance of the grounding arrangement:
ЗУ - GA
Ом - Ohm
where n – is a number of sets, vertical grounding arrangements - 9 pcs, horizontal grounding arrangement - 1 pc;
Kutil – is utilization rate, 0.63
The calculated resistance of the grounding arrangement is 1,64 Ohm.
The location of the equipment is shown in Figure 1.
Условные обозначения - Legend
- проволока стальная оцинкованная диаметром 8 мм - d8 mm steel zinc-plated wire
- полоса стальная оцинкованная сечением 30х4 мм - steel zinc-plated bar 30 x 4 mm
- универсальный зажим-соединитель для проволоки - multipurpose clamp for wire
- зажим для подключения проводника - clamp for connecting wire
- опуск токоотвода - downdrop
- вертикальный заземлитель длиной 3 м - 3 m vertical grounding arrangement
Figure 1. Equipment layout.
The list of necessary materials is given in Table 1.
Table 1. List of needed materials.
|№ п/п||Part number||Name||Quantity, pcs.||Unit weight, kg||Note|
|1.||ZZ-502-008-125||ZANDZ Galvanized steel wire (D 8 mm/ S 50 mm²; wire bundle 125 m)||5||0,39||Вес 1 метра|
|2.||GL-11545A||GALMAR Main conductor rain water gutter terminal (painted galvanized steel)||10||0,112|
|3.||GL-11551A||GALMAR Conductor connection clamp (painted zinc-plated steel)||80||0,07|
|4.||ZZ-202-015||ZANDZ Holder for a circular conductor on a flat roof (D 8 mm; plastic + concrete)||600||1,00|
|5.||GL-11703A||GALMAR Current collector facade clamp providing 15 mm elevation of the collector over the clamp (painted zinc-plated steel)||260||0,02|
|6.||GL-11514N||GALMAR Ring clamp on rainwater pipe for current collector (tinned copper)||10||0,076|
|7.||ZZ-502-304-52||ZANDZ Steel zinc-plated bar (30 * 4 mm; 52 m bundle)||4||0,96||Вес 1 метра|
|8.||ZZ-001-255||ZANDZ Threaded zinc-plated grounding rod (D16; 1.5 m; M16)||18||2,00|
|9.||ZZ-002-251||ZANDZ Threaded zinc-plated connection coupling (M16)||10||0,08|
|10.||ZZ-003-250||ZANDZ Termination for zinc-plated grounding rods (M16; zinc-plated steel)||9||0,07|
|11.||ZZ-004-250||ZANDZ Guide head for jackhammer attachment (M16; zinc-plated steel)||4||0,09|
|12.||ZZ-005-064||ZANDZ Conductor connection terminal (up to 40 mm)||25||0,312|
|13.||ZZ-006-000||ZANDZ Conductive grease||2||0,10|
|14.||ZZ-007-030||ZANDZ Waterproofing tape||9||0,40|
|15.||ZZ-008-000||ZANDZ Attachment to the hammer (SDS max)||1||0,50|
Do you have any questions regarding lightning protection and grounding for the reproduction health center? Please contact the ZANDZ Technical Center!