LIGHTNING PROTECTION OF ADMINISTRATIVE BUILDING WITH CHILLERS ON THE ROOF

Every square meter of modern high-rise buildings is very technological. In the walls and ceilings there are kilometers of cables, pipelines and ventilation shafts. Actual design technologies make it possible to rationally lay all communications so that they occupy as little space as possible, would not cover useful area, but at the same time perform their functions in the best way. One of the most important engineering systems is the ventilation and air conditioning system. Without it, being in a residential building or office becomes unbearable.

Air intake and cooling equipment, such as chillers and air conditioners, is located on the roof. It is expensive and it is desirable to protect it from lightning, protecting the chillers with rod lightning rods. In addition, a direct lightning strike into the air conditioner can bring lightning current into the building through ventilation pipes or ducts. This is another reason to organize a reliable lightning protection system with chillers for a building, the protection area of which will include all the equipment located on the roof.

ZANDZ Technical Center often provides lightning protection for buildings with rooftop chillers and air conditioning. Learn about the proven solution of the technical specialists from the text of the news.

Task

To calculate lightning protection of the administrative building with chillers on the roof.

Solution

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

1. Electric Installation Code" EIC 7th ed. (hereinafter - EIC).
2. "Instructions for organization of lightning protection of buildings, structures and industrial communications" IS 153-34.21.122-2003 (hereinafter IS).
3. "Instructions for lightning protection of buildings and structures" AD 34.21.122-87 (hereinafter - AD).

Lightning arresters are used for protection of structures from lightning strikes. A lightning arrester usually consists of a lightning rod, intercepting the lightning strike, a down conductor and a ground electrode. All these elements allow to safely drain lightning current into the ground without a damage for the protected object.

The administrative building with roof-mounted chillers belongs to the ordinary ones in terms of lightning protection in accordance with IS and to the 2nd category according to AD.

Description of the external lightning protection system of an administrative building with chillers

The set of measures to provide the required lightning protection is offered by the following solutions:

1. To protect the capacitor units in the zone B of AD, one rod lightning rod 4 m high is mounted that is attached to a metal beam and one that is mounted on the wall leading to roof (the same lightning rod protects the satellite antenna with a diameter of 0.8 m). It is taken into account that 0,7 m of the lightning rods height is used for fixation.
2. To protect roof fans, a 4 m high rod lightning rodis attached to the shaft. This lightning rod is also used to protect capacitor units. It was taken into account that 0.5 m of the height of the air terminal is takesn for fixation.
3. Down conductors are laid from lightning rods using copper-bonded wire D = 8 mm. Metallic metal structures (beams) on the roof also serve as down conductors.
4. Lightning rods are also interconnected for the arrangment of two down conductors from each lightning rod.
5. Lightning protection of the unprotected part of the object is made in the form of a lightning protection mesh using copper-bonded wire D = 8 mm, laid with the distance of not more than 6x6 m. The mesh is made so that the current has at least two different paths to the ground electrode.
6. Fixation of down conductors is performed (installation distance 0.6-1 m):
   • on a flat roof – with the help GL-11711 clamps;
   • on the walls by means of GL-11703A clamps.
7. The connection of down conductors with already laid slopes and the branching of down conductors is performed using GL-11551А clamps.
8. ll metal elements placed on the roof must be connected to the air terminal with clamps ZZ-005-064.

The layout of elements in the lightning protection system and the grounding device is shown in Figure 1. Protection zone corresponds to zone B of the AD.

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