# CALCULATION EXAMPLE OF A SKI BASE LIGHTNING PROTECTION

Winter holidays are in full swing, and lovers of active winter holidays rush to the ski resorts. The modern ski resort is a complicated complex of structures and infrastructure elements: technical and administrative buildings, hotels, lifts, transformer substation and lighting system. Is it necessary to protect it from lightning, because in winter this natural phenomenon is a rarity? In fact it is, by all means. First of all, because a “rare event” does not mean “impossible”. For example, in this video you can see what a direct lightning strike during a winter thunderstorm leads to.

Secondly, a proper lightning protection system is necessary for the ski complex to survive through the summer thunder season. Where possible, lighting towers should be used as lightning rods. Zones that remain unprotected should be equipped with rod lightning rods. Thus, the ski base will be protected from lightning not only in summer but also in winter.

Let's look at the example of the calculation of a ski base lightning protection, proposed by the ZANDZ technical center.

To calculate lightning protection of the ski base. The building under protection is an ordinary structure in terms of lightning protection in accordance with the IS and is in Category 3 according to the AD.

## Ski base lightning protection solution

The calculations are made in accordance with the following documents:

Lightning protection of buildings from lightning strikes is carried out with the help of 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.

## Description of the external lightning protection system of the ski base

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

1. High-mast lighting towers with the height of 20 m are used as lightning rods.
2. Additionally, installation of 2 rod lightning rods 4 m high, mounted to chimneys, is carried out. It is taken into account that 0,7 m of the lightning rods height is used for fixation.
3. Down conductors are laid from lightning rods using copper-bonded wire D = 8 mm.
4. Metal fence is used in some parts of the roof as down conductors. The wire connection is made using the clamp ZZ-005-064.
5. The lightning rods are also interconnected to arrange two down conductors from each lightning rod.
6. 2 descents to the artifical ground electrode are made from the fence.
7. Fixation of down conductors is performed (installation distance 0.6-1 m):

Solutions to ensure the necessary requirements for the grounding device:

1. Installation of a grounding device consisting of a horizontal electrode (copper bonded tape 4x30 mm), depth 0.5 meter and 3 vertical electrodes (rods made of copper-bonded steel with the diameter of 14 mm) 3 m long.
2. Interconnection of horizontal and vertical electrodes is carried out by using clamp ZZ-005-064.
3. The down conductor is connected to the copper-bonded tape protruding from the ground with the help of GL-11562A clamp.

Location of the lightning rods on the hotel is shown in Figure 1.

Figure 1. Plan with the layout of lightning protection elements and grounding device

## Calculation of the reliability of lightning protection in the program

The following source data are taken for the calculation:

The density of lightning strikes into the ground - 4 strikes / sq. km per year for Moscow.

The results of lightning protection calculation performed by the software, developed by OJSC "Energy Institute to the name of Krzhizhanovsky" (OJSC" ENIN ") are given in table 1. Source data and calculation results in pdf file.

Chart 1 - Results of lightning protection calculation

 № Object Lightning rod height, m Protection reliability Number of strikes into an object, year-1 Number of breakthroughs into the object, year-1 Period of srikes, year Period of breakthroughs, year 1 Ski base 4 м 0,962 0,089 0,0034 every 11 years every 294 years

Accessories for the system of external lightning protection of the ski base

Chart 2 - List of materials needs

 № п/п Fig. Product item Product Quantity Lightning protection system 1. ZZ-201-004 ZANDZ Vertical air-terminal -mast 4 m (stainless steel) 2 2. GL-21202 GALMAR Holder for interception rods GL-2110X (installed on the chimney, wall; stainless steel) 2 3. GL-20022 GALMAR GL-2110X Clamp to lightning rods for down conductors (stainless steel) 2 4. GL-11149-10 GALMAR Проволока омедненная стальная (D8 мм; бухта 10 метров) 1 5. GL-11747A GALMAR Copper-bonded steel wire (D8 mm; coil of 10 meters) 110 6. GL-11703A GALMAR Clamp for the roof covered with metal profiles / corrugated sheets, for down conductor (painted galvanized steel) 10 7. GL-11562A GALMAR Clamp to the facade / wall for a down conductor with elevation (15 mm high; painted galvanized steel) 2 Grounding device 8. ZZ-005-064 ZANDZ Clamp for connecting conductors (up to 40 mm) 7 9. GL-11075-50 GALMAR Copper-bonded tape (30 * 4 mm / S 120 mm²; coil of 50 meters) 2 10. ZZ-001-065 ZANDZ Copper-bonded threaded grounding rod (D14; 1.5 m) 6 11. ZZ-002-061 ZANDZ Threaded coupler 4 12. ZZ-003-061 ZANDZ Starting tip 3 13. ZZ-004-060 ZANDZ Driving head for a jackhammer 2 14. ZZ-006-000 ZANDZ Conductive grease 1 15. ZZ-007-030 ZANDZ Waterproof tape 1 26. ZZ-008-000 ZANDZ Header for a jackhammer (SDS max) 1