Lightning protection zones

According to IEC 61312-1, the entire installation is classified into different lightning protection zones (LPZ):

LPZ 0A
The zone where a direct hit is possible and where objects must be capable of carrying the full lightning current. In addition, the unattenuated electromagnetic field is very dangerous (lightning current test pulse of first stroke attends 10/350 µs).

LPZ 0B
The zone where a direct hit is not possible, but the unattenuated electromagnetic field is present (lightning current test pulse is 10/350 µs). This zone is determined by the external lightning protection system consisting of the air termination, down conductor and earth termination system.

LPZ1
The zone where a direct hit is not possible and the currents in all conductive components are lower than in LPZ 0A and LPZ 0B. In this zone, the electromagnetic field is attenuated according to the screening measures applied. RF, signal and supply lines leading into this zone can be protected by lightning protection components. They may base on a number of different operating principles.

If a further reduction of the current or of the electric field is necessary, additional subsequent zones must be established (LPZ2, etc.). Additional lightning protection components applied here form the fine protection system complementing the standard protection ensured by zone LPZ1.

For optimum protection, all electric supply and signal lines should enter the protected area at one single place. At this point, they must be connected to the bonding bar by surge protection devices. At every interface between one LPZ and the next, the potential equalization must be established like this. This classifies lightning protectors to be a part of the bonding system. They provide basically an interference-event triggered bonding for signal-carrying lines.

Special lightning protection principles for RF applications allow even a continuous bonding of lines. The grounding must always be in accordance with IEC 61024-1. The grounding of the installed lightning protectors, their connections to the bonding bar of the structure or equipment have to be prepared very carefully to achieve the lowest possible resistance and inductance to ground (refer to section "Knowledge Base").