Real calculation of lightning protection for an educational institution

30.03.15 , , ,

Our company recieved another request for lightning protection calculation and selection of equipment. This time it was necessary to define a set of measures to ensure the necessary requirements to the lightning protection system of the laundry at the school-recovery center. Our technicians love such requests and were happy to make the calculations smiley

According to the industry standard 153-34.21.122-2003 "Instructions for lightning protection of buildings, structures and industrial communications", educational institutions refer to the usual buildings, from the point of view of lightning protection and to the third category according to AD 34.21.122-87 "Instructions for lightning protection of buildings and structures". Requirement for reliability - 0.9.

Calculation results for the object:

the density of lightning strikes into the ground - 6 strikes / sq. km per year;
the total number of strikes into the system - 0,037 (once in 163 years);
the total number of breakthroughs - 0.0028;
system reliability - 0.923;
likelihood of a breakthrough into all system objects - 0,077 (every 330 years).

The complex of measures to ensure necessary requirements for the lightning protection system is represented by the following solutions:

Installation of four rod lightning rods, two 4 m high and two 4.7 m high. The mounting is performed to the wall of the building.
Arrangement of down conductors with the use of copper-bonded wire D = 8 mm. Lightning rods are also interconnected for the organization of at least two down conductors from each down conductor.. Arrangement of equipment in Figure 1.

Installation of the grounding device, consisting of three vertical electrodes 3 m in length, united by a horizontal electrode (copper-plated tape with the cross-section 30x4 mm). The distance between the vertical electrodes is at least 5 meters, the distance from the horizontal electrode to the walls of the building 1 m, embedment 0.5 - 0.7 meters.

Real calculation of lightning protection for an educational institution

The list of the necessary equipment to carry out a complex of measures for lightning protection:

№	Fig.	Product item	Equipment	Quantity, pcs.
1		GL-21103G	GALMAR Vertical lightning rod (air terminal-mast) (4 meters)	2
2		GL-21202	GALMAR holder for air-terminal mast GL-21103G to the wall (stainless steel)	4
3		GL-21104G	GALMAR Vertical lightning rod (air terminal-mast) (4,7 meters)	2
4		GL-20022	GALMAR Clamp to the air-terminal mast for down conductors (stainless steel)	4
5		GL-11149-50	GALMAR Copper-bonded wire (D 8mm / S 50 mm²; coil 50 meters)	1
6		GL-11149-20	GALMAR Copper-bonded wire (D 8mm / S 50 mm²; coil 50 meters)	1
7		GL-11551A	GALMAR clamp for the connection of down conductors (painted galvanized steel)	10
8		GL-11747A	GALMAR Clamp on the roof covered with metal profile / corrugated deck for the down conductor (painted galvanized steel)	50
9		GL-11703A	GALMAR Clamp to the facade of the down conductor (painted galvanized steel)	20
10		GL-11562A	GALMAR Contorl clamp for the connection of down conductors wire + tape (painted galvanized steel)	3
11		ZZ-001-065	ZANDZ Copper-bonded threaded ground rod (D14; 1,5 m)	6
12		ZZ-002-061	ZANDZ Threaded coupler	4
13		ZZ-003-061	ZANDZ Starting tip	3
14		ZZ-004-060	ZANDZ Guiding head for a breaker hammer	2
15		ZZ-006-000	ZANDZ Conductive grease	1
16		ZZ-008-000	ZANDZ Breaker hammer header (SDS max)	1
17		ZZ-005-064	ZANDZ Сlamp for conductor connection (up to 40 mm)	3
18		GL-11075-20	GALMAR copper-bonded tape (30 * 4 mm / S 120 mm²; coil of 20 meters)	2