Lightning Protection and Grounding Design for Pre-Fabricated Modular Buildings (Container Units)

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Task:

Facility: rotation camp for 150 employees. A modular building made of 64 typical container units.

Dimensions: 40 x 13.7 m.

Total building area: 548 m².

Number of floors: 2.

Building roof height: 5.26 m.

Soil: sand clay, clay loam.

Soil resistivity at the site: 150 Ohm/m.

It is required to perform calculation and develop a lightning protection and grounding design while meeting the requirements of the effective regulatory documents.

Solution:

According to SO 153-34.21.122-2003 (Table 2.1), rotation camp building is classified as conventional facilities in terms of lightning protection. Protection level III; reliability of protection against direct lightning strikes (DLS) is 0.9.

To protect the building and equipment located on the roof, a roof wire lightning protection ZANDZ is provided, which is an external lightning protection system that includes a wire suspended over the protected facility on special supports located on the flat roof of the facility.

1. ZANDZ Wire lightning protection support (zinc-plated steel; with one concrete base). Current collectors provided as a 8 mm wire are connected to the lightning rod using a special clamp made of galvanized steel. The suspended wire is also secured using a special clamp located at the support top.

The delivery set includes:

• wire lightning protection support made of galvanized steel;
• clamp for securing wire with cross-section 50 mm2 located on the support top;
• clamp for connecting a current collector, which is located at the support base;
• concrete base for securing support.

Let's assume the support height being equal to 3 m (art. ZZ-205-103).

2. ZANDZ galvanized steel lightning protection wire (art. ZZ-204-001).

Lightning protection wire directly catches the lightning strike and drains it through the support structure to the ground terminal. ZZ-204-001 is a spiral wire made of galvanized steel wires according to GOST 3063-80.

The ZANDZ wire has a high mechanical strength, low stretch ratio (to reduce slag) and can hold and safely drain lightning currents.

3. Earthing is made using a copper-plated strip with cross-section 30 x 4 mm (GL-11075) installed in the trench at the depth of at least 0.5 m from the ground surface and at the distance of at least 1 m from the building foundation, and is attached to the lightning protection bus (IDD PE bus). Current collectors are attached by control clamps GL-11562A.

4. Copper-plated D8 mm wire is used as current collectors (art. GL-11149), and is secured by facade holders GL-11703A.

5. Protection from secondary lightning effects and high voltage is provided by connection of metal pipes, utilities, cable sheaths at the building entry to the earthing circuit.

Calculation of the protection zone for a dual wire lightning protection (according to item 3.3.2.2 and item 3.3.2.4 of SO 153-34.21.122-2003)

Protection zone is calculated at the ground level and at the building roof level.

h_sup = 8,41 m is height of the wire protection support considering building height;

h = 7,39 м – m is maximum wire slack;

h₀ = 0,87 х h = 0,87 х 7,39 = 6,43 m – is protection zone cone height (for reliability level 0.9);

r₀ = 1,5 х h  = 1,5 х 7,39 = 11,09 m – is protection zone cone radius (at the ground level);

L = 13,17 m – is distance between wires.

По табл. 3.7 СО:

L_max = 6 х h = 6 х 7,39 = 44,34 m;

L_с = 3 х h = 3 х 7,39 = 22,17 m.

L < L_сx, respectively, according to formula 3.7 of SO:

h_c = h₀ – is slack height of the protection zone in the center between lightning arresters.

According to SO:

r_x = r₀ х (h₀ – h_x) / h₀ = 11,09 х (6,43 – 5,26) / 6,43 = 2,017 m m is maximum semi-width of the lightning protection zone in the horizontal cross-section at height h_х = 5,26 m (building roof height).

Calculation of a ground terminal resistance

Resistance of a horizontal electrode:

where:

ρ = 150 Ohm m is soil resistivity;

b = 0,03 m strip width of a horizontal electrode;

h = 0,5 m is a laying depth of the horizontal mesh;

L_гор = 160 m is total length of the horizontal electrode.

The ground terminal design resistance is 2.878 Ohm which is less than the rated resistance of 10 Ohm.

List of required materials

Appendix: design in DWG and PDF formats

ZANDZ Трос грозозащитный стальной оцинкованный - ZANDZ Galvanized steel lightning wire
Токоотвод-проволока омедненная D 8 мм/S 50 - Copper-plated lightning wire D 8 mm/S 50
Зона защиты двойного тросового молниеотвода - Protection zone of the dual wire lightning arrester
Зажим для подключения токоотвода - Clamp for connecting current collectors
Изм. - Chng
Кол. уч. - ModQnty
Лист - Sheet
№ док - Doc. No.
Подп. - Sign.
Дата - Date
Стадия - Stage
Лист - Sheet
Листов - Sheets
Технической центр ZANDZ.com - ZANDZ.com Technical Center
Формат А3 - Format A3
Разраб. - Dev. by
Проверил - Checked by
Н.контр. - QC
Молниезащита вахтового поселка и быстровозводимых зданий - Lightning Protection of a Rotation Shift and Pre-Fabricated Buildings
Вид слева - Left view
Согласовано - Approved by
Инв. № - Inv. No.
Подп. и дата - Sign. and date
Согласовано - Approved by
ZANDZ Стойка тросовой молниезащиты (оцинкованная сталь; с одним бетонным основанием) ZZ-205-103 (hon = 3 м): - ZANDZ Lightning protection wire support (galvanized steel; with a single concrete base) ZZ-205-103 (hon = 3 m):
В комплект поставки входят: - The delivery set includes:
- стойка тросовой молниезащиты из оцинкованной стали; - lightning wire support made of galvanized steel;
- зажим для крепления троса сечением 50 мм2, размещенный на вершине стойки; - clamp for securing wire with cross-section 50 mm2 located on the support top;
- зажим для подключения токоотвода, размещенный у основания стойки; - clamp for connecting current collector located at the support base;
- бетонное основание для фиксации стойки. - concrete base for securing a support.
Конструкция стойки рассчитана на установку в I-III ветровом районе по СНиП 2.03.11-85. The support is intended for installation in the 1-3rd wind region according to SNiP 2.03.11-85.
Искусственный заземлитель Rз не более 10 Ом – полоса омедненная 30х4 мм/S 120 мм2 GL-11075 Artificial grounding Rg not more than 10 Ohm – 30 x 4 mm copper-plated bar/S 120 mm2 GL-11075

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