# How to implement lightning protection for a gym?

09.12.16

Healthy lifestyles are becoming fashionable again. Every day, thousands of people go to places to exercise — gyms, fitness centers, swimming pools. At all such facilities, there is special electrical equipment or accessories, which means that such buildings must meet certain requirements for electrical safety.

How to implement lightning protection and earthing for a gym? We’ll tell you in our sample calculation provided by technical experts.

### Initial data:

• specific resistance of soil— 100 Ohm*m (loam);
• length — 42 m;
• width — 19 m;
• height of walls — 9.55 m;
• ridge height: 11.14 m.

Figure 1. Overall dimensions of the object.

Gyms are referred to as “regular” structures in compliance with SO and to category 3 as per RD. Required reliability — 0.9.

As per EIC (PUE)-7, par.1.7.103, the total spreading resistance of the earthing electrodes (including natural) of all the repeated groundings of the PEN conductor in each overhead line at any time of the year must not exceed 10 ohms at a line voltage of 380 V for a three-phase power supply or 220 V for a single-phase power source.

The protection of buildings and structures against lightning discharges is ensured with lightning diverters. A lightning rod is a device rising above the facility that diverts the lightning current into the ground without entering the facility. It comprises an interception rod that directly takes on the lightning discharge, a conductor wire and an earthing rod.

### Required arrangements for lightning protection

The action plan to ensure compliance with the necessary requirements for a lightning protection system is as follows:

1. Installation of two vertical mast interception rods of 5.7 meters in height over the edges of the roofing ridge (see Figure1).
2. Installation of an earthing device comprising three vertical electrodes of 3 meters in length, integrated with a horizontal electrode (copper-plated band of 30x4 mm cross-section). The distance from the horizontal electrode to the object is under 1 meter, the distance between vertical electrodes is 21 m. The burial depth is 0.5 – 0.7 meters.
3. All metal objects on the roof shall be connected to conductor cables.

The resistance calculation for the grounding device:

The design resistance of the earthing device equals 4.75 Ohm, which is less than the required of value 10 Ohm.

Results of calculations carried out with software developed by the Krzhizhanovsky Power Engineering Institute:

Density of discharges of lightning into the ground – 6 strikes per sq. km per year.

Total number of strikes onto the system — 0.067 (once per 90 years).

Total number of lightning breakthroughs — 0.0069.

System reliability — 0.9..

Probability of breakthroughs into all the system objects - 0.01 (once per 131 years).

Figure 2. Equipment layout.

Не менее - Minimum
Молниеприемник-мачта высотой 5,7 м (GL-21105G) - Lightning rod-mast 5.7m height (GL-21105G)
Проволока омедненная стальная диаметром 8 мм (GL-11149) - Steel copper-plated wire with diameter 8 mm (GL-11149)
Полоса омедненная стальная сечением 30x4 мм (GL-11075) - Steel stripe copper-plated with section 30х4 mm (GL-11075)
Электрод D = 14 мм, L = 3 м. - Electrode D = 14 mm, L = 3 m.

Table 1. List of equipment and required materials.

№ п/п Рис. Артикул Наименование Кол-во, шт.
1. GL-21105G GALMAR Vertical lightning rod (air terminal-mast) (5.7 meters) 2
2. GL-21201 GALMAR Holder for air terminal - mast GL-21101G to the wall (stainless steel) 2
3. GL-20023 GALMAR Clamp to the mast interception rod - GL-21104G / GL-21105G for conductor wires (stainless steel) 2
4. GL-11149-50 GALMAR Copper-coated wire (D 8mm / S 50 mm²; coil of 50 meters) 4
5. GL-11149-20 GALMAR Copper-bonded wire (D 8mm / S 50 mm²; coil 20 meters) 1
6. GL-11551A GALMAR Clamp for connecting conductor cables (painted galvanized steel) 10
7. GL-11747A Clamp on the roof covered with metal profile / corrugated deck for the down conductor (painted galvanized steel) 200
8. GL-11703A GALMAR Clamp for fixing conductor cables to the facade (painted galvanized steel) 20
9. GL-11562A GALMAR Control clamp for the connection of down conductors "wire + band" (painted galvanized steel) 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 jackhammer 2
14. ZZ-006-000 ZANDZ Conductive grease 1
15. ZZ-008-000 ZANDZ Nozzle for a jackhammer (SDS max) 1
16. ZZ-005-064 ZANDZ Clamp for connecting conductors (up to 40 mm) 3
17. ZZ-007-030 ZANDZ Waterproofing tape 1
18. GL-11075-50 GALMAR Copper-plated tape (30 * 4 mm / S 120 mm²; coil 50 meters) 1
19.

 ZZ-500-110
ZANDZ Earthing conductor (10m; S25, single-core, with a tip for a D8 bolt) 1

If you have any questions on the lightning protection of sports facilities, contact the Technical center ZANDZ!