Example of lightning protection of an administrative building of a large organization

July 13, 2017

All high-rise buildings should have a reliable lightning protection. But there are facilities with special requirements in terms of lightning protection. And they are not always about higher reliability. Sometimes, good elaboration of the design and highest quality of the used materials are no less important. Such facilities may include administrative buildings and offices of leading companies. Such facilities are a "visiting card" of the company. Lightning protection and grounding systems there should be both reliable and be able to fit the facility design well so that to avoid damage to its appearance.

"The Dispatcher Center for System Control of Operating Modes of Train Oil and Oil Products by the JSC "Transneft - Verkhnyaya Volga", city of Nizhny Novgorod" is one of such facilities. The lightning protection system for the facility has been recently designed by the ZANDZ Technical Center. Read more about the work done!

Транснефть – Верхняя Волга - Transneft – Verkhnyaya Volga

Figure 1. Facade of an administrative building

Task:

To calculate the lightning protection system for an administrative building. The protected facility is classified as a conventional facility in terms of lightning protection according to SO and to Category 3 according to RD.

Solution:

Calculations of the lightning protection are made in conformity with the following documents:

• "Electrical Installations Code" (hereinafter, EIC), EIC 7th edition.
• "Guidelines for Arrangement of Lightning Protection of Buildings, Structures, and Industrial Utilities" SO 153-34.21.122-2003 (hereinafter, SO).
• "Guidelines for Arrangement of Lightning Protection of Buildings and Structures" RD 34.21.122-87 (hereinafter, RD).

Protection of buildings against lightning strikes is provided by using lightning arresters. Lightning arrester is a device that is elevated over the protected facility through which the lightning current goes into the ground bypassing the protected facility. It consists of a lightning rod that directly accepts the discharge of a lightning , a current collector, and a grounding electrode.

Description of the external lightning protection system

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

• Lightning rods are installed:
  • 6 with the height up to 7 m (1 m for securing);
  • 1 with the height up to 10 m (1.5 m for securing).
• Along the roof perimeter, current collectors are laid using the copper-plated wire D = 8 mm in at least 20 meters, which are connected to an artificial grounding electrode.
• Lightning rods are also interconnected to arrange two current collectors from each lightning rod.
• Along the building perimeter, at design elevations + 21,000 and +37,000, horizontal bars made of copper-plated steel with the diameter of 8 mm are laid, which are secured to the wall using clamps GL-11703A.
• Band connection to current collectors is made using clamps GL-11551А.
• The main conductor cables are mounted (installation step 0.6-1 m):
• on a flat roof using clamps GL-11711;
• on the walls using clamps GL-11703A.
• Connection and branching of main conductors are usually made using clamps GL-11551А.

A set of measures to ensure the requirements for the grounding arrangement is based on the following solutions:

•  A horizontal circuit is laid around the building. The circuit is made of corrosion-resistant copper-plated steel bar 4 x 30 mm, depth 0.5 m, the distance to the building wall at least 1 m.
•  The horizontal electrodes are connected to each other using connection terminal ZZ-005-064.

Figure 2. Lightning protection and grounding elements layout plan

Protection reliability calculation

The density of lighting discharges into the ground is 4 strikes/sq. km per year;

To calculate the lightning protection from the ground, a zero level is taken at -4,000.

The results of the calculation of the lightning protection performed using the software developed by the OJSC "Krzhizhanovsky Energy Institute" (OJSC ENIN) are provided in Table 1.

Table 1. Results of lightning protection calculations

№	Facility	Lightning rod height, m	Protection reliability	Number of strikes into the facility, year - 1	Number of blowouts into the facility, year - 1
				Period of strikes, year	Period of blowouts, year
1	Administrative building	7 and 10 m	0,926	0,65	0,048
				once per 2 years	once per 21 years

 

The list of necessary materials is given in Table 2.

№	Fig.	Part number	Product	Quantity
Lightning protection system
1.		ZZ-201-010-3	ZANDZ Lightning mast, vertical, 10 m high, with a set of 3 wall fasteners (stainless steel)	1
2.		ZZ-201-007-3	ZANDZ Lightning mast, vertical, 7 m high, with a set of 2 wall fasteners (stainless steel)	6
3.		ZZ-202-002	ZANDZ Clamp to the lightning rod D42 mm for current collectors (stainless steel)	7
4.		GL-11149-50	GALMAR Steel copper-clad wire (D8 mm; 50 wire bundle)	20
5.		GL-11551A	GALMAR Current collectors connection clamp (painted galvanized steel)	30
6.		GL-11711	GALMAR Flat roof clamp for the current collector (D8 mm; plastic, concrete)	210
7.		GL-11703A	GALMAR Clamp for fastening the current collector with elevation (15 mm height; painted galvanized steel) to the facade/wall	800
8.		GL-11562A	GALMAR Control clamp wire + bar (painted galvanized steel) for connecting current collectors	6
Grounding arrangement
9.		ZZ-005-064	ZANDZ Conductor connection clamp (up to 40 mm)	6
10.		GL-11075-50	GALMAR Copper-plated strip (30 * 4 mm / S 120 mm²; 50-meter strip bundle)	3
11.		GL-11075-20	GALMAR Copper-plated bar (30 * 4 mm / S 120 mm²; bundle 20 meters)	1
12.		ZZ-007-030	ZANDZ Waterproofing tape	2

 

The listed equipment provides reliable protection from lightnings which has been proved by the calculations made in the software.

To protect the equipment and electrical utilities inside the building, we recommend employing a set of measures which allows preventing dangerous overvoltage.

1. Protection in a main distribution panel

The main distribution panel contains the surge protection device SDP Class I+II+III PP BCB TNS 25/100 selected according to a three-phase input to the building and power system TN-C-S or TN-S.

The connection is made consecutively (V connection). We recommend using the fuse F1 (see the diagram) without a delay, with the rate of up to 125 A.

If an input breaker (or protective fuses instead of it) calculated according to the power grid load and its rated value is less than 125 A, the installation of additional fuses F1 is not required.

The SDP connection scheme is shown in the Figure 3.

Figure 3. Class 1+2+3 SPD connection scheme

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