6.1 External LPS
The required level of protection (LPL I, II, III or IV) for the External Protection System shall be determined through the Risk Assessment which shall be conducted in terms of SANS 62305-2. Once the LPL is established the parameters for the external protection system are selected i.e. conductor sizes, down conductor spacing, rolling sphere radius, mesh size, protective angle etc.
– Air Termination System (ATS)
The function of the ATS is to prevent any direct lightning strikes from damaging the structure by intercepting the lightning strike, preventing penetration into the protected space. A correctly designed system will significantly reduce the risk of a direct strike to the structure. It is not possible to completely eliminate this risk.
An ATS can consist of the following components:
– Spanned wires and cables
– Conductors in conductor holders
It is important that the ATS covers corners and edges of a structure as these areas are most vulnerable to a direct strike. It is also important that any masts used are able to withstand the wind loading for the area in which it is installed.