Why lightning protection is necessary

The necessity to install a lightning protection system in a private house is determined by the house owner based on the probability of destruction or damage of the property by lightning. National regulations do not impose requirements on the mandatory implementation of a lightingin protection system for private houses.

The probability of a lightning strike into an object depends primarily on the duration of thunderstorms in the area of its location.

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This relation for a rectangular house 10x12 m in size and a ridge height of 8 m is shown in the table below:

The average annual duration of storms in hours	The probability of a lightning strike into a house 10 x 12 x 8 m in size*
10-20	1 strike in 332 years
20-40	1 strike in 166 years
40-60 (Moscow and the region.)	1 strike in 83 years
60-80	1 strike in 60 years
80-100	1 strike in 47 years
100 and more	1 strike in 39 years

A lightning protection system includes a device for protection against direct lightning strikes (external lightning protection system) and devices for protection from the secondary effects of lightning (internal lightning protection system). In some cases, a lightning protection system may comprise only internal or only external devices.

An external lightning protection system protects an object from a direct lightning strike. Its impact is dangerous primarily because of the high lightning channel temperature, which can result in the inflammation of combustible structures of the house.

More information about the dangers of lightning storm can be found in a series of articles "Lightning protection for beginners" by Professor E. M. Bazelyan.

External lightning protection system components and construction

An external lightning protection system consists of three components: lightning protection rods, which receive a direct lightning strike; a grounding device that ensures the spreading of current in the soil, and down conductors connecting the first two elements.

Lightning protection rods

To choose the number and height of the lightning protection rods it is necessary to calculate the protection zones. The estimated protection zone of air terminal masts should cover the whole volume of the protected facility.

A protection zone of a lightning protection rod represents a cone with its apex matches the vertical axis of the mast. The dimensions of such cone depend on the required reliability.

According to SO 153-34.21.122-2003 "The instructions for lightning protection of buildings, structures and industrial communications", the dimensions of cone ensuring 0.9 reliability are determined by the following formulas:

/formula

/Protection zone of a single lightning rod:

^{Protection zone of a single lightning rod:

1 - protection zone boundary at level hx2 - the same as at the ground level}

Installing a free-standing mast to protect the house is not feasible, as its height should be substantial (up to 30 meters). This is not just expensive and labor-intensive, but also increases the total number of lightning strikes into the plot in question. An optimal solution is to place masts directly on the protected object.

One mast would be sufficient only for houses with a steeple or pyramidal roof if such mast is placed on top of the roof.

house

The reliable protection of a house with a rectangular gable roof (with the roof slope of at least 35 °) requires the installation of two masts 2 meters high at the edges of the roof ridge. For houses of a more complex shape, it is required to make calculations based on structurally practical locations of the air terminal masts installation.

A lightning protection meshed cage can be used for roofs with a maximum slope of 7 °, which is not typical for a private house roofing. In addition, the modern scientific community does not confirm the effectiveness of meshed cage protection from direct lightning strikes (you can learn more on this in "The issues and challenges of regulatory documents")webinar .

Lightning protection rods should be made of materials and have sizes (cross-sectional area, thickness) in accordance with GOST R IEC 62561.2-2014.

Down conductors

The diameter of down conductor made of round stock should be at least 8 mm. Down conductors shall be placed so that current between a lightning strike point and the soil could spread along several parallel paths, and the length of these paths should be minimal. It is recommended to lay down conductors at a maximum distance from doors and windows.

Direct contact of a down conductor having a correctly chosen cross-section with wall and roof materials cannot cause a fire as the increase of the conductor temperature under the influence of the lightning current is not enough even to char wood, not to mention other low-flammable materials. Additionally, the thermal effect is very short.

Grounding device

Whenever possible, use steel foundation piles or interconnected reinforcing bars of the building's concrete foundation as a grounding device. This solution is applicable when connectivity is possible (the outlets of fittings are available) and when bituminous and bituminous-latex coatings are used as a waterproofing. Epoxy and other polymer coatings prevent electrical contact between the foundation and the soil, and therefore, such foundations can not be used as a natural grounding.

Ready-made grounds should be placed under the asphalt pavement or rarely visited places located away from walkways.

A grounding device connected to the lightning protection rod should have the following minimum structure:

Three or more vertical electrodes at least 3 meters long combined with a horizontal electrode with a distance between the vertical electrodes of at least 5 meters.

Ground electrodes shall be located outside the protected facility and be spaced apart from each other as much as possible. The preferred depth of the electrodes laying shall be at least 0.5 m; a distance from the walls of the object shall be 1 meter.

The dimensions of grounds shall comply with the requirements of the corrosion and mechanical resistance. Normative documents (GOST R 50571.5.54-2011) specify the minimum dimensions of electrodes depending on materials they a made of.

Notes

^{* The probable number of lightning strikes per year for a facility is calculated using the following formula:}
/formula:
where:
A is house length in meters
B is house width in meters
H is house height in meters
n is the average annual number of lightnings that stike 1 km2 of earth's surface, 1 / (km2*year)

The specific density of lightning strikes into the area n is determined based on the average duration of storms in hours as follows:

Average annual duration	Specific density of lightning strikes into earth n, 1 / (km2*year)
10-20	1
20-40	2
40-60	4
60-80	5.5
90-100	7
100 and more	8.5

Lightning strike period:

External lightning protection components

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Air terminal mast

A traditional vertical air termination device as a two-meter(GL-21101G) or four-meter (GL-21103G) mast that comes with a tip screwed on.

The mast is made of stainless steel and represents a pipe with a wall thickness of 2 mm.

	GL-21101G	GL-21103G
^Weight:	^{5 kg}	^{10 kg}
^Height:	^{2000 mm}	^{4000 mm}
^{Air terminal diameter:}	^{35 mm}	^{35 mm}
^{Wall thickness:}	^{2 mm}	^{2 mm}

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GL-21101G / GL-21103G air terminal mast holder for fastening to a chimney (stainless steel)

GL-21202 holder (delivered as a set of two units) allows attaching a GL-21101G / GL-21103G air terminal mast to a chimney or an air duct.

The holder is fixed to the wall by ten anchors (five for each holder), which provides a very high mechanical strength of the structure.

The holder made of stainless steel.

Bolts, washers, and nuts are made of stainless steel.

	GL-21202
^{"Leg" thickness:}	^{6 mm}
^{"Legs" width (at the extremes)}	^{515 mm}
^{"Leg" height (at the extremes)}	^{190 mm}
^{The distance from the air terminal to the wall}	^{190 mm}

It is possible to use the same holder designed for the installation on the wall. Please visit a separate page for the description.

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GL-21101G / GL-21103G air terminal mast clamp for down conductors (stainless steel)

Gl-20022 clamp allows connecting a down conductor wire electrodes with a diameter of 8 mm to GL-21101G / GL-21103G air terminal masts.

The clamp can be used to fix two conductors (from different sides).

The holder made of stainless steel.

Bolts, washers, and nuts are made of stainless steel.

	Gl-20022
^{Down collector diameter:}	^{8 mm}
^Weight:	^{0.2 kg}
^Length:	^{62 mm}
^Width:	^{30 mm}
^{Height (with the bolt)}	^{100 mm}

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Down conductor - copper-bonded wire (D8 mm)

GL-11149 copper-bonded wire is made of rolled steel covered with 99.9% purity copper using electrolytic deposition method to form a coating with a thickness of at least 0.070 mm to form a molecular and unbreakable bond the steel.

The wire with a diameter of 8 mm (cross-sectional area of 50 mm²) is used as down conductors as components of external lightning protection.

	GL-11149
^{Weight of 1 meter:}	^{0.41 kg}
^Diameter:	^{8 mm}
^{Cross-sectional area:}	^{50 mm2}

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Down connector building face fixing clamp
(painted galvanized steel)

The clamp is used to quickly attach wire down conductors with a diameter of 8 mm to the building front / wall.

NO screw is included (see an example on the photo).

	GL-11704A
^{Down collector diameter:}	^{8 mm}
^Elevation	^-
^Weight:	^{0.02 kg}
^Length:	^{35 mm}
^Width:	^{25 mm}
^{Height (without fittings):}	^{16 mm}

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Down conductor clamp for roofs covered with steel profiles/ corrugated boards
(painted galvanized steel)

The clamp with rubber sealing bushing is used to to quickly fix wire down conductors with a diameter of 8 mm on roofs covered with steel profiles/ corrugated boards.

NO screw is included (see an example on the photo).

	GL-11747A
^{Down collector diameter:}	^{8 mm}

^Weight:	^{0.05 kg}
^Length:	^{35 mm}
^Width:	^{30 mm}
^{Height (without fittings):}	^{38 mm}

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Test clamp to connect
"wire+wire" down conductros
(painted galvanized steel)

The clamp allows disconnecting the external lightning protection system (down conductors) from the grounding device (for example, to carry out measurements). It allows connecting D8 wire down conductors in a straight line.

	GL-11563A
^{Down conductor diameter:}	^{8 mm}

^Weight:	^{0.13 kg}
^Length:	^{62 mm}
^Width:	^{30 mm}
^{Height (including bolts):}	^{35 mm}

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ZANDZ and GALMAR modular grounding

GALMAR and ZANDZ ground rods are made of steel bonded with a copper coating at least 0.250 mm thick to ensure up to 100 years of guaranteed service life of the device.

The design of the rods allows to interconnect them and drive into the soil to a depth of 40 meters to achieve low grounding resistance within a small area. The installation is carried out by one person without the use of construction and specialized machinery.

The modular grounding can be purchased either as off-the-shelf kits or as separate components.

Detailed information about the modular grounding technology is available on a separate page.

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The horizontal ground electrode is copper-bonded wire (D10 mm)

GL-11150 copper-bonded wire is made of rolled steel covered with 99.9% purity copper using electrolytic deposition method to form a coating with a thickness of at least 0.070 mm to form molecular and unbreakable bond the steel.

The wire with a diameter of 10 mm (the cross-sectional area of 80 mm²) is used as down conductors in an external lightning protection system.

	GL-11149
^{Weight of 1 meter:}	^{0.63 kg}
^Diameter:	^{10 mm}
^{Cross-sectional area:}	^{80 mm2}

Please visit the relevant pages of our website to view the full range of components for lightning protection.

Buy

Please visit our convenient online store on Buy page to view the current prices and buy all components required to build a high-quality and reliable external lightning protection system.

An example of a lightning protection system based on GALMAR and ZANDZ products

A list of product that can be used to build a complete external lightning protection system is shown on the right side of the page. All the proposed products comply with the requirements of national regulations as to the minimum size, contact connection quality, mechanical strength, service life, etc.

Air terminal masts are fixed on vertical surfaces of walls, chimneys or air ducts. When positioning the masts one should consider the overhanging length the roof slope over the walls and examine the possibility to use 21101G / 21102G holders.

Most of the down conductor clamps are available in two versions: painted galvanized steel and copper. The fastening of down conductors by clamps is performed in increments of 1 meter. The type of clamps is selected based on the roof surface type (flat, ray, skate, facade, etc.) and the roofing material (steel profile, natural tile, etc.). Please note that anchor bolts are not included with the facade and roof clamps. The type and length of such bolts should be selected depending on the base material.

It is also possible to mount down connectors on the roof drain system of the house (fix them to the water-shoot or gutter).

The grounding device is assembled from components of a modular grounding system.

An example of a complete set of products for the lightning protection of a rectangular house having dimensions 8x10 m with a ridge height of 8 m and a roof slope angle of 35 °.

^{An example of a complete set of products for the lightning protection of a rectangular house having dimensions 8x10 m with a ridge height of 8 m and a roof slope angle of 35 °.}

The roofing material is metal tiles, and the wall material is timber.
A = 10 m; B = 8 m; H = 8 m; α = 35 °;
Hf = 3.5 m; Hw = 4.5 m; Lsl = 6.1 m

The air terminals are connected together to make two down conductors going from each air terminal.

Lightning protection rod
GL-21101G	GALMAR air terminal mast	2 pcs
GL-21202	GALMAR wall holder for GL-21101G air terminal mast (stainless steel)	2 pcs
GL-20022	GALMAR down conductor clamp for GL-21101G air terminal mast (stainless steel)	2 pcs
Down conductor
GL-11149-10/20/50	GALMAR copper-bonded wire (D 8mm / S 50 mm²; coil 10/20/50 meters)	40 m
GL-11551A	GALMAR down conductor connection clamp (painted galvanized steel)	6 pcs
Clamps for down conductor fastening on the roof
GL-11564A	GALMAR clamp for fastening a down connector on a ridge with the down conductor protruding 15 mm over the clamp (painted galvanized steel)	11 pcs
GL-11747A	GALMAR down conductor clamp for roofs covered with steel profiles / corrugated boards (painted galvanized steel)	12 pcs
Down conductor clamps
GL-11703A	GALMAR down conductor clamp for the fronts of buildings with down conductor protrusion of 15 mm (painted galvanized steel)	10 pcs
GL-11562A	GALMAR test clamp for connecting the down conductor "wire +tap" (painted galvanized steel)	2 pcs
Grounding device
GL-11075-10/20/50	GALMAR copper-bonded tape (30*4 mm / S 120 mm²; coil 10/20/50 meters)	20 m
ZZ-001-065	ZANDZ threaded copper-bonded ground rod (D14; 1.5 m)	6 pcs
ZZ-002-061	ZANDZ threaded coupler	4 pcs
ZZ-003-061	ZANDZ grounding tip	3 pcs
ZZ-004-060	ZANDZ driving head for jackhammer tup	1 pcs
ZZ-005-064	ZANDZ conductor clamp	5 pcs
ZZ-006-000	ZANDZ conductive paste	1 pcs
ZZ-008-000	ZANDZ jackhammer tup (SDS max)	1 pcs