# An interesting project: lightning protection for stables

An interesting order has been recently processed by our technicians. This time we were asked to calculate the necessary arrangements for lightning protection of stables in Smolensk region. We wrote several times about residential houses and "popular" objects, but we don't get such requests every day. We are sure you will be interested to learn more about the project!

An object: Stables presents itself a two-storey L-shaped building 25.3 meters long and 20.3 m wide (on the wide side). The height of the structure, together with the chimney reaches 9 meters. Shingles is used as roof coating. The soil at the site is accepted as sandy loam with the resistivity to current spreading of 150 ohm * m.
Task: it is necessary to make calculations and offer solutions for lightning protection and grounding.
Solution:
As usual, we use the following regulatory documents for the calculations:

Taking into account the possible consequences mentioned in the IS document , the stables should be referred to the usual type of buildings, and from the point of AD - to the third category of lightning protection. According to the standards described in paragraph 1.7.103 EIC, the total resistance of spreading of ground electrodes of repeated groundings of the PEN-conductor of each overhead line at any time of the year should not exceed 10 ohms at the line voltage of 380 V of a three-phase power supply or 220 V of a single-phase power source. In this case, the shape of the object and its roof suppose protection against lightning discharges, made by the lightning protection mesh. Beside the mesh, lightning protection system also includes a down conductor and ground electrode.

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

1. Installation of three air terminal masts, 4 meters high. Down conductors are organized using copper-bonded steel wire D = 8 mm, and all lightning rods are connected along the roof ridge. (See. Fig.1).
2. Installation of the grounding device, which consists of five vertical electrodes D = 14 mm, 3 m long, united by the horizontal electrode (copper-bonded tape 30x4 mm). The distance from the electrode to the walls of the building is not less than 1 m, the distance between the electrodes is not less than 5 m, penetration is 0.5 - 0.7 meters.

Figure 1. Arrangment of lightning protection and grounding equipment. Protection zone

Calculation of resistance of a grounding device:
Vertical electrode resistance:

Where Pэкв - equivalent soil resistivity, Ohm*m;
L - vertical electrode length, m;
d - vertical electrode diameter, m;
T - deepening - the distance from the ground to the ground electrode system, m;

Where t - deepening of the electrode top, m

Horizontal electrode resistance:

where D - horizontal electrode diameter, m;
t - depth of the horizontal mesh, m;
Lгор- horizontal electrode length, m.

Impedance of the grounding device:

where n - number of kits;
kисп- Utilization ratio;

The design resistance of the grounding device is 6.21 Ohms, which is less than the required impedance of 10 Ohm.

The list of necessary equipment:

 No. Fig. Product item Product Q-ty. 1 GL-21103G GALMAR Vertical lightning rod (air terminal-mast) (4 meters) 3 2 GL-21201 GALMAR Holder for air terminal - mast    GL-21101G to the wall (stainless steel) 2 3 GL-21202 GALMAR Holder for air terminal - mast     GL-21101G to the chimney (stainless steel) 1 4 GL-20022 GALMAR clip to air-terminal- mast GL-21101G / GL-21102G / GL-21103G for down conductors (stainless steel) 3 5 GL-11149-50 GALMAR Copper-bonded wire (D 8mm / S 50 mm²; coil 50 meters) 2 6 GL-11551A GALMAR Clamp for connecting down conductors (painted galvanized steel) 15 7 GL-11747A Clamp on the  roof covered with metal profile/ corrugated deck, for down conductor (painted galvanized steel) 60 8 GL-11703A GALMAR Clamp to the facade of the down conductor (painted galvanized steel) 40 9 GL-11562A GALMAR Control clamp for connecting down conductors wire+tape (painted galvanized steel) 5 10 ZZ-001-065 ZANDZ Copper-bonded threaded grounding pin    (D14; 1,5 m) 10 11 ZZ-002-061 ZANDZ Threaded coupler 6 12 ZZ-003-061 ZANDZ Starting tip 5 13 ZZ-004-060 ZANDZ driving stud for a breaker hammer 2 14 ZZ-006-000 ZANDZ Conductive grease 1 15 ZZ-008-000 ZANDZ Cap for a breaker hammer (SDS max) 1 16 ZZ-005-064 ZANDZ Clamp for connecting conductor(up to 40 mm) 5 17 ZZ-007-030 ZANDZ Water-proof tape 2 18 GL-11075-50 GALMAR Copper-bonded tape    (30 * 4 mm / S 120 mm²; coil 50 meters) 1

Implementation of the described events will provide a building, stables, as well as people and cattle with a reliable protection against direct lightning strikes.
Do you have questions about selecting, designing and calculation of grounding and lightning protection systems? Write us and we will help!