LIGHTNING PROTECTION OF A HOSPITAL COMPLEX

Lightning protection of medical establishments is an integral part of electro and fire-security. It is important to note that when designing lightning protection of hospital complexes it is necessary to protect all the objects included into this complex.

Recently, the ZANDZ Technical Center received a request for the development of lightning protection system for a hospital complex of 12 buildings. We will study the solution for the main building, which was offered by our specialists.

Initial data:

object: main building of a hospital complex;
sizes: 48m x 22m x 8.9 m;
ridge height: 10,1 m;
the power supply is fed along overhead lines;
soil resistivity - 100 Ohm * m.

Task:

Calculate external lightning protection and grounding system for the main building of a hospital complex.

Solution:

Lightning protection and grounding of a hospital complex are performed in accordance with:

The object refers to III category of lightning protection in accordance with AD and to "ordinary" in accordance with IS. Required lightning protection system reliability – at least 0.9.

According to EIC-7, p. 1.7.103. The total speading resistance of the ground electrodes (including natural) of all repeated groundings of the PEN conductor of each overhead line at any time of the year should not exceed 10 ohms at line voltage of 380 V of the three-phase power supply or 220 V of a single-phase power source.

The set of measures on the provision of required lightning protection measures to lightning protection and grounding systems for a hospital complex is presented by the following solutions:

Lightning protection is carried out with the help of air terminals masts 4,7 m high (GL-21104G) which are installed on the walls of bay windows (distance for installation - up to 1 m) and ridge lightning rod 2 m high (GL-11521SS).
Copper-bonded steel wire is used as down conductor (thickness of the copper coating not less than 70 mcm), d8mm wire (GL-11149).
Installation of down conductors is carried out with the help of clamp GL-11747 - on the roof, GL-11703A -on vertial surfaces. Distance between the clamps- from 0.8 up to 1.0 meter.
To connect rolled metal over the length and in the nodes, a universal clamp GL-11551A is used.
All metal elements, placed on the roof must be connected to the down conductor with the help of clamps GL-11545A. Stairs and hand railings are connected with the help of a clamp-bridge GL-11514N.
Copper-coated steel electrodes 3 m long are used in places of downdrops as a vertical ground electrodes. Copper-bonded steel tape with the cross-section of 30x4 mm (GL-11075) uniting all vertical electrodes is used as a horizontal ground electrode system. The distance to the object foundation- not less than 1 m. Burial depth of the tape 0,5 - 0,7 m.
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.
If there are metal reinforce concrete framings, they must be connected to down conductors/ grounding device.
Connection to the grounding device is carried out with the help of clamps ZZ-005-064.

Results of the calculation carried out with the software developed by the JSC "Energy Institute to the name of G.M. Krzhizhanovsky (JSC "ENIN"):

The density of lightning strikes into the ground - 4 strikes / sq. km per year;
The total number of strikes into the system in: 0.039 (once in 26 years);
The total number of breakthroughs (strikes directly into the object passing lightning rods) - 0.0037 (once in 270 years).
System reliability – 0,906.

Grounding device resistance calculation:

Grounding device resistance calculation:

The design resistance of the grounding device is 6,58 Ohm, which is less than the required resistance of 10 Ohm.

Location of equipment is shown in figure 1.

Figure 1 - Arrangement of lightning protection and grounding equipment of the main building of a hospital complex.

The list of equipment is given in Table 1.

Table 1 - Materials requirement list.

№	Product item	Name	Quantity, pcs.	Note
1.	GL-11521SS	GALMAR lightning rod 2 meters high for installation in threaded holders (M16; stainless steel)	1
2.	GL-11525	GALMAR Ridge holder for lightning rod (thread M16; connection of d10 mm down conductor; bronze)	1
3.	GL-21104G	GALMAR Vertical lightning rod (air terminal-mast) (4,7 meters)	4
4.	ZZ-203-001	ZANDZ Fastening for a lightning rod to the wall (stainless steel)	4
5.	ZZ-202-002	ZANDZ Clamp to the lightning rod D42 mm for down conductors (stainless steel)	4
6.	GL-11149-50	GALMAR Copper-bonded wire (D 8mm / S 50 mm²; coil of 50 meters)	4	In coils
7.	GL-11545A	GALMAR Clamp on the gutter for a down conductor (painted galvanized steel)	10
8.	GL-11551A	GALMAR Clamp for connecting down conductors (painted galvanized steel)	20
9.	GL-11703A	GALMAR Clamp to the facade for down conductor with its elevation above the clamp to 15 mm (painted galvanized steel)	30
10.	GL-11747A	GALMAR Clamp for the roof covered with metal profiles / corrugated sheets, for down conductor (painted galvanized steel)	120
11.	GL-11514N	GALMAR clamp to the drain pipe for a down conductor (tape of tinned copper + stainless steel clamp)	10
12.	GL-11075-10	GALMAR Copper-bonded tape (30 * 4 mm / S 120 mm²; coil of 10 meters)	3	In coils
13.	ZZ-001-065	ZANDZ Copper-bonded threaded grounding rod (D14; 1.5 m)	4
14.	ZZ-002-061	ZANDZ Threaded coupler	3
15.	ZZ-003-061	ZANDZ Starting tip	2
16.	ZZ-004-060	ZANDZ Driving head for a jackhammer	1
17.	ZZ-005-064	ZANDZ Clamp for connecting conductors (up to 40 mm)	7
18.	ZZ-006-000	ZANDZ Conductive grease	1
19.	ZZ-007-030	ZANDZ Waterproof tape	2
20.	ZZ-008-000	ZANDZ Header for a jackhammer (SDS max)	1

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