An instance of figuring out how to protect an acetone warehouse and filtration pumping station in the Samara area from lightning

As long as it creates the necessary zone of protection, a single lightning arrester (single lightning protection system) can be used to protect many structures on the property from lightning strikes. A free-standing lightning mast that has the necessary height is one of the best kinds of lightning receivers in these situations. The mast is installed into the ground using a concrete foundation. Its design accounts for the environmental loads (temperature, wind, snow, and earthquake) that the mast would encounter while in operation to ensure dependable and reliable service. The Technical Center ZANDZ.com has suggested a lightning receiver of a similar kind to safeguard an item made up of two buildings.

The facility consists of two closely spaced buildings that are part of a single technological system. Throughout the working process, no explosively concentrated gas production occurs. According to the classification of explosive areas according to the Electrical Installations Code (EIC), Rev. 7., Chapter 1.7 (hereinafter referred to as EIC) such areas belong to Class B-Ia:

Class B-Ia areas are areas located in those rooms in which, during normal operation, explosive mixtures of flammable gases (irrespective of the lower concentration limit of ignition) or vapors of flammable liquids with air are not formed but are possible only as a result of accidents or malfunctions.

According to RD 34.21.122-87 Guidelines for Arrangement of Lightning Protection of Buildings and Structures (hereinafter – RD), the objects of protection belong to the II category of lightning protection according to.

At the customer's request, a freestanding lightning detector was selected as a protection measure. The Technical Center ZANDZ.com projected that the mast's height of 25 meters would provide enough protection, accounting for zone B. The mast's design is based on wind load and local climate conditions. In addition to directing lightning current into the earth, the suggested grounding arrangement also protects the electrical infrastructure from harm. A ground with excellent conductivity of 30 ohm*m made the task easier and allowed users not to worry about achieving the target grounding resistance of 10 ohms.

Calculation of Lightning Protection and Grounding of the Object

The activities were carried out in accordance with the EIC, RD and SO 153-34.21.122-2003 Guidelines for Arrangement of Lightning Protection of Buildings, Structures, and Industrial Utilities (hereinafter CO).

Lightning protection of the facility

The set of arrangements ensuring compliance with the lightning protection requirements is based on the following solutions:

• installation of 1 free-standing lightning protection system with a height of 25 m, see Figure 1;
• the protection radius and the height at which the protection zone B of RD is constructed are shown in Figure 2.

Figure 1. Vertical lightning protection system 25 m ZZ-201-025-В3-Сн4-С7.
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Figure 2. Protection zone of a single lightning rod

Figure 3. The layout of the lightning protection elements of the filtration pumping station and acetone warehouse
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Grounding

• for a lightning protection system, a horizontal grounding electrode for the current flowing in two directions at 90 degrees between them. The ground terminal is made of corrosion-resistant steel zinc-plated strip having the cross-section 4 x 50 mm, installation depth 0.5 m;
• in each direction, at a distance of about 5 m from the lightning protection system, a vertical electrode with a length of 3 m is installed;
• horizontal ground terminal is laid in the form of contours around the site objects, which are connected to each other;
•  the connection of horizontal and vertical electrodes to each other and to lightning protection systems is carried out using ZZ-005-064 clamps.

Calculation of a ground terminal resistance

According to the customer, estimated soil resistivity is taken to be 100 Ohm * m.

Warning! In case the Customer provided erroneous and limited soil data, the above calculation of a grounding arrangement is considered incorrect. If the soil resistivity differs from the calculated one, it is necessary to perform computations with a real value. If the normalized impedance of the grounding arrangement is exceeded, there must be introduced the design corrections.

Resistance of a horizontal electrode:

where p is soil resistivity, Ohm*m;
b is horizontal electrode width, m;
h is horizontal electrode depth, m;
L_hor is horizontal electrode length, m.

Vertical electrode resistance:

where p is soil resistivity, Ohm*m;
L is vertical electrode length, m;
d is vertical electrode diameter, m;
T  is depth, i.e. the distance from the ground surface to the ground terminal, m;

where t s depth of the top of the electrode, m.

Electrical impedance of the grounding arrangement:

where n — is number of sets;
k_util — utilization ratio; 

The rated resistance of the grounding arrangement is 0.48 Ohm, which is less than the required value 10 Ohm.

Table 1. List of required materials

Item	Fig.	Part number	Product	Qty
Lightning protection system
1		ZZ-201-025-В3-Сн4-С7	Vertical lightning arrester 25 m (zinc-plated steel; with parts embedded under the foundation; up to the 3rd wind district; up to the 4th snow district; seismic up to 7 points)	1
Grounding arrangement
2		ZZ-202-012	ZANDZ Clamp for a circular wire and a strip (D14-20 mm; up to 40 x 6; galvanized steel)	30
3		ZZ-502-504-31	ZANDZ zinc-plated steel strip (50 * 4 mm; 31 m bundle)	7
4		И-С3-ЦГ5/8-30	IGUR Grounding rod, hot-dipped zinc-plated steel, 1.5 m long, 16 mm in diameter	4
5		ZZ-002-061	ZANDZ Threaded connecting coupling	3
6		ZZ-003-061	ZANDZ starting tip	2
7		ZZ-004-060	ZANDZ Guide head for jackhammer attachment	1
8		ZZ-006-000	ZANDZ Conductive grease	1
9		ZZ-007-030	ZANDZ Waterproof tape	10
10		ZZ-008-000	ZANDZ Attachment to the hammer (SDS max)	1

Do you have any inquiries concerning lightning protection for the acetone storage, the filtration pump station, or other facilities? Please, contact the ZANDZ Technical Center!

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