LIGHTNING PROTECTION OF A THEATRE

There are no specific requirements to lightning protection of theatres in AD. But designers will have to remember that this object is often one of "visit cards" of the city and lightning protection should not affect its appearance. The engineers of the ZANDZ Technical Center considered this detail when they got a task to calculate lightning protection. We offer you to get familiarized with project details and calculation example.

 

Lightning protection calculation

Object: theatre.

Figure 1 - Plan of the object.

 

Task: calculate lightning protection systems for a theatre.

 

Protection of buildings and structures against lightning discharges is ensured by lightning rods. A lightning rod is a device rising above the facility that diverts lightning current into the ground without entering the facility. It consists of a lightning rod which directly takes the lightning discharge upon itself, a down conductor and a ground electrode.

 

Solutions to meet the requirements to a lightning protection system:

1.    Lightning protection is carried out in accordance with EIC 7th edition, IS 153-34.21.122-2003 "Instructions for lightning protection of buildings, structures and industrial communications" (hereinafter IS) and AD 34.21.122-87 "Instructions for lightning protection of buildings and structures" (hereinafter AD).

2.    The object refers to category 3 of lightning protection. System reliability must be not less than 0,9.

3.     The lightning protection of the object is made with the help of 4 vertical air-terminal masts 4 m high on railings with the help of welding, 2 vertical lightning rods 10 m high on the wall and 4 vertical lightning rods 2 m high on the roof ridges (GL-11521SS)

4.     Connection of down conductors to lightning rods and downdrop to the grounding device;

5.    Installation of down conductors is carried out with the help of clamp GL-11564A - on a ridge, GL-11747A -on horizontal surfaces, GL-11545A- on a gutter, GL-11514 on a rain-pipe. Distance between the clamps- from 0.8 up to 1.0 meter;

6.     To connect rolled metal over the length a universal clamp GL-11551A is used;

7.    All metal structures and communications must be connected to the down conductor with the help of clamps GL-11545A. Stairs, railings are connected with the help of GL-11514 clamp.

8.     Installation of a grounding device consisting of 3 vertical electrodes of 3 m in length united by a horizontal electrode (copper-bonded tape of 30x4 mm). The distance from the horizontal electrode to the object should be not less than 1 m, deepening 0.5 - 0.7 meters;

9.    In case of presence of the existing grounding device, they should be united into one grounding device in accordance with EIC p.1.7.55.

 

Results of the calculation carried out with the software developed by the JSC "Energy Institute to the name of G.M. Krzhizhanovsky (JSC "ENIN"):

Density of lightning strikes into the ground - 4 strikes / sq. km per year;

The total number of strikes into the system - 0,27 (once in 4 years);

The total number of breakthroughs is 0.027 (once in 37 years);

System reliability — 0.9;

Probability of breakthrough into all the system objects - 0.10.

 

Grounding device resistance calculation:

The design resistance of the grounding device is 9.8 Ohms.

 

Figure 2 shows the arrangement of equipment.

Table 1 gives the list of the required equipment and materials.

Figure 2 – Layout of lightning protection equipment of a theatre

 

Table 1 - List of need in materials.

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