On the Assistance and Questions page, a guest has posted an interesting question:
...Is it possible to use not a special holder for mounting a rod (like this one http://www.zandz.ru/molniezashchita/vneshnyaya/zazhim_na_krovlyu_plastik.html), but a simple mounting band, mounting the rod directly to a stainless steel sheet? I.e. attach it to the sheet with mounting band and self-tapping screws.
After thorough examination of the question, our technical experts gave the following answer:
The stainless steel sheet of the roofing should be in direct contact with the down conductor (in this case, the network). If the rod is to be mounted to a stainless steel sheet with mounting band, the following steps should be taken:
- It is necessary to consider and choose the materials for the stainless steel sheet, rod, band and screws carefully. The choice you make is very important, as it prevents against electrochemical corrosion when different metals are in contact
- It is necessary to provide tight contact between all metal parts to avoid sparking and burning of the metal where the contact loosens
If it is impossible to take these steps, special holders are to be used.
An air termination network will not protect roofing from a direct lightning strike, which should also be taken into account. In the standard SO 153-34.21.122-2003 (more precisely, in table 3.2), the minimum thickness of roofing is given that will protect it from damage and being burnt through (4 mm for iron).
|Level of protection||Material||Thickness t, mm, minimum|
Requirements for roofing thickness, SO 153-34.21.122-2003
Roofing of that thickness can be used as a lightning rod by itself without mounting the network. An air termination network is only necessary when there is electrical continuity between the roofing elements. The thickness of a stainless steel sheet is often less than 4 mm, which is why it is impossible to protect it from damage using a air termination network. In such a case, other means of protection are to be used, for example, lightning rods. They can take a direct lightning strike and protect the roofing from damage. The network will be useful as an addition to achieve an even distribution of current and lower the electromagnetic effect of lightning on the object.