# LIGHTNING PROTECTION OF A DRYING BARN

Tobacco supports burning, that means it can become a source of a fire at an object where it is being dried. Moderm tobacco dryers present themselves pavillions of a container type and must be protected from lightning.

ZANDZ Technical Center got a task to calculate external lightning protection system of a drying barn (tobacco dryer). Let's see what solutions we got.

Initial data:

• object sizes: 4,5 m x 7.4 m;

• height: 2,5 m;

• ridge height: 3 m;

• pipe height: 4.5 m;

• soil resistivity: 100 Ohm * m.

• calculate external lightning protection system;

• calculate grounding device.

Solution:

The arrangements were fulfilled in compliance with:

Drying barn refers to "ordinary" objects in compliance with IS and to category 3 as per AD.

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

1. A free standing air terminal mast 10 m high is used as a lightning rod.

2. Transient resistance between all down conductors, metal sheets and panels must be nor more than 0,05 Ohm at an obligatory annual control before the storm season in accordance with AD 34.21.122-87, item 3.4.

3. All metal elements placed on the roof must be attached to the metalwork of the object.

4. All reinforced concrete foundations, plinths should be used as natural ground electrodes and be attached to the artificial grounding device.

5. Copper-bonded steel tape with the cross-section of 30x4 mm in the form of a contour is used as a horizontal ground electrode. Vertical ground electrodes 3 m long are installed in places of connection to metal structure. The distance to the object foundation is at least 1 m. Deepening of the tape 0,5 - 0,7 m. The tape is connected with the help of ZZ-005-064 clamp along its length and in the nodes.

6. The calculated value of the grounding device resistance is 4,52 Ohm.

7. Connection to the grounding device is carried out with the help of clamps ZZ-005-064.

8. In accordance with the EIC-7 ed., P.1.7.55 - Grounding devices for protective grounding of electrical installations of buildings and structures and lightning protection of the 2nd and 3rd categories of these buildings and structures, as a rule, should be common.

Results of calculations for the protection zone in compliance with the IS:

h=10 m;

Height of the cone according to the IS chart. 3.4:

The radius of the cone according to the IS chart. 3.4:

Grounding device resistance calculation:

The design resistance of the grounding device is 4,52 Ohms

Location of equipment and protection zone are shown in figure 1.

Figure 1 - Location of equipment.

Молниеприемник мачта высотой 10 м  - Air terminal mast 10 m high
Полоса омедненная стальная сечением – Copper-bonded steel tape with the cross-section of 30 x 4 mm
Электрод – Electrode D=14 mm, L=3 m

The list of equipment and required materials is given in Table 1.

Table 1 - Materials requirement list.

 № Figure Product item Name Quantity, pcs. 1. ZZ-201-010 ZANDZ Vertical lightning rod 10 m (galvanized steel; with embedded fittings for placing under the foundation) 1 2. ZZ-001-065 ZANDZ Copper-coated threaded grounding rod (D14; 1.5 m) 8 3. ZZ-002-061 ZANDZ Threaded coupler 5 4. ZZ-003-061 ZANDZ Starting tip 4 5. ZZ-004-060 ZANDZ Driving head for a jackhammer 2 6. ZZ-006-000 ZANDZ Conductive grease 1 7. ZZ-008-000 ZANDZ Header for a jackhammer (SDS max) 1 8. ZZ-005-064 ZANDZ Clamp for connecting conductors (up to 40 mm) 8 9. ZZ-007-030 ZANDZ Waterproof tape 2 10. GL-11075-50 GALMAR Copper-bonded tape (30 * 4 mm / S 120 mm²; coil of 50 meters) 1

Do you have questions or you need to calculate lightning protection and grounding for a drying barn? Send your request to info@zandz.ru.