12.09.14 , , , ,
It is widely believed that a down conductor must run outside the building. However, when installing an external lightning protection system installers often "hide" down conductors under the facade of the building. Is this acceptable?
- According to the instructions for lightning protection of buildings, structures and industrial communications (industry standard 153-34.21.122-2003) it is permitted to run down conductors non-insulated from the protected object both on the wall surface and in the wall of the building in case, if the wall is made of a noncombustible material.
- If the wall is made of a combustible material, down conductors must be laid directly on the surface of the wall. It is necessary so the temperature rise would not present danger for the wall material.
- If the temperature rise of down conductors presents danger to the combustible wall material, then down conductors should be located 10 cm from the object to be protected. At the same time, metal clamps and brackets for the fixation of down conductors can come into contact with the wall.
It is not recommended to place down conductors in the downpipes and close to windows and doors.
Dashed line - down conductor, laid under the elements of the building facade