How to reliably protect a historic site from lightning without spoiling its appearance.
Lightning protection of architectural monuments requires a flexible approach. On one hand, a lightning strike can damage the facade decor of a historic building, split stone elements, change the color of metal parts or melt them. In some cases, a fire caused by lightning, causes irreparable damage to a cultural heritage site. Therefore, its lightning protection should be as reliable as possible.
On the other hand, a structure of historical value must retain its original appearance. In order not to spoil it, it is necessary to very carefully select lightning rods and down conductors, as well as to design their placement.
It is better to use decorative lightning rods for lightning protection of historical objects, for example ZZ-201-002-D. Due to the ability to customize this lightning rod, it will harmoniously complement the historical object of any architectural style. But in some cases, ordinary rod lightning rods, for example ZZ-201-004, won't look like an alien element on a historic building. We used such interception rods for external lightning protection of one of Moscow estates, about the restoration of which was a lot written in the print press. Let's study the project of its lightning protection and grounding in more detail.
Calculate lightning protection of a cultural heritage site of federal significance. The building under protection is an ordinary structure in terms of lightning protection in accordance with the IS and is in Category 3 according to the AD.
Calculations of lightning protection and grounding of a historical object are made in accordance with the following documents:
- "Electrical Installation Code" EIC 7th ed. (hereinafter - EIC).
- "Instructions for organization of lightning protection of buildings, structures and industrial communications" IS 153-34.21.122-2003 (hereinafter IS).
- "Instructions for lightning protection of buildings and structures" AD 34.21.122-87 (hereinafter - AD).
Protection of buildings from lightning strikes is carried out with the help of lightning rods. A lightning rod is a device rising above a facility that diverts lightning current into the ground without entering the facility. It consists of a lightning rod which directly takes the lightning discharge upon itself, a down conductor and a ground electrode.
Description of external lightning protection system of a historical object
Measures to meet the requirements for the lightning protection system:
- Installation of two 4 m high rod lightning rods on a pipe. It is taken into account that 0.5 meter of the rod length is used for fastening.
- Installation of five rod lightning rods with 2 m high on the ridge.
- Lightning rods are interconnected to arrange two down conductors, using copper-bonded wire D=8 mm from each lightning rod. Down conductors are connected to the artificial ground electrode. Down conductors is carried out (installation distance 0.6-1 m):
- Connection and branching of down conductors is carried out with the help of GL-11551А clamps.
Measures to ensure the requirements to the grounding device:
- Installation of a grounding device consisting of a horizontal electrode (copper bonded tape 4x30 mm), depth 0.5 meter and 3 vertical electrodes (pins made of copper coated bonded steel with a diameter of 14 mm) 3 m long
- Interconnection of horizontal electrodes is carried out by using ZZ-005-064 clamp.
- The down conductor is connected to the copper-bonded tape protruding from the ground with the help of GL-11562A clamp.
The arrangement of the elements of the lightning protection system and the grounding device is shown in Figure 1 and in the sketch in a separate file. The protection zone in the figure corresponds to zone B of the AD.
Figure 1 - The layout of the elements of lightning protection and grounding device for the historical site
Components for external lightning protection system of a historical object
Table 1 - Materials requirement list
Do you have questions about lightning protection of historic sites? Please contact our ZANDZ Technical center!